Abstract for implantable cardioverter defibrillator (ICD) therapy

Abstract

Aims Cardiac resynchronization therapy (CRT) has been shown in several clinical trials to improve symptoms and exercise capacity in patients with advanced heart failure. The first clinical trials of CRT-D devices were based on populations who already met a standard indication for implantable cardioverter defibrillator (ICD) therapy. In these patients, when CRT is contemplated, a CRT-D device is used. In a broad population of patients with advanced heart failure, the choice of adding ICD therapy is less clear.

Methods and results Results of several clinical trials of CRT and ICD use in heart failure are reviewed. An analysis of data suggests that CRT may reduce death due to progressive heart failure. Recently, the COMPANION trial has reported that CRT can reduce long-term morbidity and mortality. CRT can be delivered as a pacemaker only, or in combination with an ICD. Taken alone, an ICD can improve survival in select groups of patients with left ventricular dysfunction; however, adverse effects have been seen, such as worsening heart failure.

Conclusion There are no clinical trials designed specifically to address the relative merits of CRT delivered by pacemaker versus ICD. Based on our knowledge of the effects of both, along with data from recent clinical trials, it appears as though the preponderance of evidence is in favor of CRT-D. More will be learned from clinical trials currently underway

Key Words: Heart failure • Implantable cardioverter defibrillator • Cardiac resynchronization therapy
An ICD is an electrical device that is implanted in the chest to monitor and record, and if necessary, correct episodes of arrhythmias.

An ICD consists of two parts:

*

A pulse generator - a relatively small device (about 40cubic cm, weighing about 100g) that is implanted under the muscle or skin below the left collarbone. This generator consists of a lithium battery, energy delivery components and electrical circuitry all sealed in a case.

*

One or more thin, coated wire electrodes that connect to the pulse generator to your heart. The wire electrode(s) travel through the vein between the implant site and the heart.

The electrode(s) in the heart monitor the heart rhythm. If an arrhythmia is detected, the generator activates the appropriate treatment to eliminate the arrhythmia, as programmed by your cardiologist.

NASHVILLE, Tenn. - June 22, 2006 - Saint Thomas Hospital today announced the launch of a landmark clinical trial for a new heart-failure device that combines the capabilities of an implantable cardioverter defibrillator (ICD) with a new technology that continuously records pressure inside the heart, and can alert physicians to potential heart-failure complications before they worsen.

The investigational device, known as the Chronicle® ICD, features both the traditional ICD’s ability to restore normal heart rhythm following a dangerously fast heartbeat and the first-ever real-time tracking of pressure inside the heart, body temperature, patient activity and heart rate 24 hours a day. Patients implanted with a Chronicle ICD will transmit that information from home, using a standard phone line, to their physicians who view the recorded data from a secure Web site in their office and then potentially make changes to patients’ medications or diet.

“Chronicle ICD represents a fundamental change in the way heart-device makers and cardiologists will address chronic diseases such as heart failure in the years to come,” said the clinical trial’s principal investigator, Dr. Mark Aaron, Saint Thomas Hospital. “It’s no longer enough to wait until patients develop symptoms of worsening heart-failure - patients and physicians need technology, like Chronicle ICD, that has the potential to provide an early and accurate indication of deterioration in heart failure status, thereby allowing clinicians to take appropriate preventive measures.”

The study seeks to determine the safety, efficacy and functionality of the Chronicle ICD when used in heart-failure patients indicated for ICD therapy. Sponsored by Medtronic, the blinded study is a prospective, randomized, multi-center clinical trial at up to 75 sites in the United States involving approximately 850 patients with mild to moderate heart failure (NYHA Class II and III).

Heart failure is a condition in which the heart pumps blood inadequately, leading to reduced blood flow and possible back up of blood in the veins and lungs. Heart failure can lead to sudden cardiac arrest.

Saint Thomas Hospital is a member of Saint Thomas Health Services, a faith-based ministry with 7,500 associates serving Middle Tennessee at Saint Thomas and Baptist Hospitals in Nashville, Middle Tennessee Medical Center in Murfreesboro and Hickman Community Hospital in Centerville.
St. Paul, MN, March 9, 2004 — St. Jude Medical, Inc. (NYSE: STJ) announced today that data from its RHYTHM (Resynchronization HemodYnamic Treatment for Heart Failure Management) ICD clinical trial showed a statistically significant improvement in peak VO2 and exercise duration for patients treated with cardiac resynchronization therapy (CRT). All prospectively defined primary safety and efficacy endpoints of the study were successfully met. The announcement was made today in conjunction with the American College of Cardiology’s 2004 Scientific Session in New Orleans, Louisiana.

“The Epic™ HF ICD evaluated in this study effectively combines pacemaker therapy, defibrillation therapy and left-heart stimulation to treat the complexities of heart failure,” said Kyong T. Turk, M.D., of the Nebraska Heart Institute, Lincoln, Nebraska, who enrolled the most patients in the RHYTHM clinical study. “These multiple sophisticated therapies in one compact, easy to implant device give me significant flexibility to optimize patient care.”

The primary efficacy endpoint of the RHYTHM ICD study was improvement in cardiac function as measured by patient peak VO2 during cardiopulmonary exercise testing. The clinical trial was sized based on an expectation that the CRT arm of the study would show a 1.6 ml/kg/min improvement in peak VO2 compared with the control group, which did not have the CRT feature activated. The actual observed improvement level for CRT compared to control was 1.93 ml/kg/min, which was statistically significant (p=0.001). Secondary endpoints concerning NYHA class and Quality of Life were also statistically significantly improved with CRT (p=0.048 and p=0.009, respectively), with the six minute walk test demonstrating a strong trend toward significance (p=0.07). The study evaluated resynchronization effectiveness, defibrillation system efficacy, defibrillation system safety and left ventricle lead performance.

“This is a significant prospective, randomized study, which adds to the growing body of evidence supporting the therapeutic effectiveness of cardiac resynchronization therapy as an adjunct to optimal medical therapy for heart failure patients,” added Eric S. Fain, M.D., Senior Vice President, Development and Clinical/Regulatory Affairs for St. Jude Medical’s Cardiac Rhythm Management business. “The RHYTHM study has a rigorous protocol with more stringent inclusion/exclusion criteria than previous studies, so all of the participating RHYTHM ICD investigators should be congratulated on achieving this important milestone.”

Patients enrolled in the RHYTHM ICD study have an approved indication for an ICD; symptomatic, advanced heart failure (NYHA Class III/IV) not due to reversible causes, for at least six months, despite receiving optimal pharmacological therapy for a minimum of 90 days; an ejection fraction of = 35% (volume of blood pumped compared to volume filled), and a prolonged QRS duration (ventricular activity shown in an electrocardiogram).

The RHYTHM study evaluated the St. Jude Medical Epic™ HF model V-338 implantable cardioverter defibrillator (ICD), which is used to treat heart failure patients who are also at risk of dangerously fast heart rhythms (ventricular tachyarrhythmias). The Epic™ HF ICD offers negative AV/PV hysteresis with search capability designed to ensure a high percentage of biventricular pacing. It’s the world’s smallest high-voltage cardiac resynchronization device, designed to make implantation easier while improving patient comfort and cosmetic appearance. The device delivers 30 joules of energy in a physiologic-shaped 36-cc ICD.

The device was paired with either the Aescula™ model 1055K or QuickSite™ model 1056K left heart lead. During the separate QuickSite phase of the RHYTHM ICD Study, the implant success rate of the QuickSite lead was 94.4%. All prospectively defined endpoints of the QuickSite phase of the study were met.

Data from the RHYTHM study is the basis for submission to the U.S. Food and Drug Administration (FDA) for approval of the devices used in the study. St. Jude Medical reaffirms its previous guidance that it expects FDA approval of the studied devices by the May 2004 NASPE/Heart Rhythm Society meeting.

Heart failure is one of the most widespread cardiac afflictions, affecting approximately five million people in the United States. About 550,000 new patients are diagnosed with heart failure each year. The majority die within five years of diagnosis.

ICD means Implanted Cardioverter Defibrillator. Another name is AICD, for Automatic ICD. ICDs are miniature, internal versions of those shock paddles paramedics use to zap people back to life after a cardiac arrest.
The device is really a small electric generator hooked up to wires called leads. The generator is made of electronic circuits plus a battery sealed into one unit. A typical ICD weighs about 4 ounces, and measures about 1/2 inch thick by 2 inches wide.
The lead (or leads) are the wires that connect the ICD to your heart. They are flexible insulated wires with an electrode tip. The tip is placed against the heart wall and carries electrical impulses from the ICD to the heart. It also sends information from your heart back to the ICD for storage as data, like files on the hard drive in your computer.
An ICD lead has a shocking coil (some leads have 2 coils) on its tip to deliver large amounts of energy to the heart. Wire coils make up the inside of the lead.

ICD diagramThe Implant - This procedure generally takes about 2 hours. During this procedure, you’ll be sedated with an IV drug, but you’ll be breathing on your own, unlike open heart surgery - which this is not. You will be pretty much out of it, but not asleep. A local anesthetic will also be given so your skin being cut doesn’t hurt you.
A cut is made under your collarbone, and the ICD is implanted under your skin in the upper chest (sometimes in the abdomen). A vein near your collarbone is cut during the procedure so the lead (or leads) can be guided through the cut vein into your heart’s chambers, beginning with the right ventricle. The tip of the lead touches your heart’s inner wall.
You may need another lead positioned in the upper right chamber of your heart. Where the leads go depends on your individual needs. You might need a lead placed just under the skin next to your rib cage. This would be placed through a small cut in your left side. Sometimes a lead is placed on the outside of your heart.
After the leads are in place, they’re tested to make sure they read your heart beat properly. Then the leads are stitched to nearby tissue so they stay put. Finally, the leads’ ends are hooked up to the generator. Your doctor will deliberately make your heart go into a funky rhythm. That’s so he can test your ICD and make sure it will shock your heart back into normal rhythm on its own.
For a short time after the implant, the electrode at the end of the lead will actually “grow into” the wall of the ventricle - this won’t interfere with heart function. You won’t sense any of this because the inside wall of the heart is not sensitive to pain.

Batteries - Most ICDs now have a battery life of 5 to 7 years. The battery will be checked now and then at your doctor’s office. The ICD has an internal beeper that will alert you if the battery gets too low. When the battery wears down, the whole ICD generator unit has to be replaced. This is done like the original procedure but since leads usually do not have to be replaced, it’s quicker and easier.

How It Works - An ICD monitors your heart all the time but only shocks you if it’s software spots a rhythm problem. When it detects an incorrect heart rhythm, it can do one of 3 things:

1. implanted ICDPace your heart like a pacemaker for a short period of time. You may not even feel this. The ICD’s software calculates the speed of a tachycardia by averaging 4 or 5 heart beats from just before the arrhythmia - your ICD is always on the job. Then it uses a percentage of that average heart rate to pace your heart. It paces your heart at a faster than usual rate. This is called “overdrive” pacing.
Why pace your heart at a fast rate instead of just knocking it all the way back to normal? Well, the ICD is trying to control your heart rhythm to prevent your fast heart rate from turning into fibrillation, which is very dangerous. Trying to slow your heart down all the way quickly probably wouldn’t work.
If your ICD can temporarily pace your heart at a fast rate - but at a constant speed and in a steady rhythm - it may be able to avoid zapping you, by letting your heart get control of its own rhythm again. Letting your heart rate just keep getting faster and faster could result in fibrillation - and a zap!
2. Cardiovert your heart. This is a relatively low energy shock to persuade your heart to get back into proper rhythm. How will this feel to you? Unfortunately, it might as well be an out and out zap. Studies show that all shocks using more than 1.5 joules of “juice” feel the same to you - the person getting the shock. So, what makes a “cardioversion” different from a “defibrillation?”
Let’s say your ICD detected tachycardia and tried to pace your heart like I described above, but it didn’t work. Your ICD now tries to “cardiovert” your heart to normal rhythm and rate. What’s the difference? The ICD gets ready to shock you but it waits for a certain point in your heart rhythm.
If the ICD can time its shock just right, it will successfully put you back into normal rhythm. Cardioversion success depends on the timing of when the ICD delivers a shock. If it shocked you at the wrong spot (time) in your heart rhythm, it could actually send you into fibrillation. Its programming prevents that.
3. Defibrillate your heart. This is the zap, a high energy shock to stop your heart. The “cardioversion” jolts your heart back into normal rhythm when it is beating too fast. A “defib” out and out stops your heart when your heart rhythm is erratic (irregular) enough to be dangerous. This gives your heart’s natural pacemaker time to get control of your heart’s rhythm again. You can read more about your heart’s natural pacemaker on my pacemaker page.
When your ICD delivers a defib (zap) it is meant to stop your heart for a programmed amount of time, not at a certain time. Often it tries to stop your heart for a full 1/2 second. Your ICD may use as much as 4 times more energy to zap you than it uses to cardiovert you.
The zap is a nasty thing and may even knock you down or knock you out, but this is a life-saver!

X-ray of patient with pacer and ICDYour ICD also records your heart’s activity just before, during, and after each episode. Your doctor can see that information in his office or in the hospital to see why you are getting zapped. This info also helps him fine-tune your ICD to prevent unnecessary zaps. He uses a device called a “programmer” to communicate with the software in your ICD. The programmer is actually a small, powerful computer, designed for one purpose only - to maintenance ICDs. There is usually no need to get to the ICD physically to reprogram it. There is an antennna built into your ICD that can receive signals from the programmer to make most software changes.

Why Do You Need An ICD? - Your heart has a natural pacemaker called the SA node (sinoatrial node), that produces electrical signals inside your heart. It’s in the upper right chamber (atrium) of your heart. The SA node’s signals travel through certain pathways in the heart muscle, causing the heart’s chambers to beat as a team. That electrical system can get out of whack for various reasons and make your heart rhythm go very fast, very irregular, or very slow - all bad. This is called arrhythmia.
Certain types of arrhythmia can be dangerous. For people with a dangerous arrhythmia that comes and goes, either anti-arrhythmic drugs or an ICD - or both - may be needed.

Living With An ICD - If your ICD shocks you, it may just be annoying or it may knock you unconscious. If you get a shock, call your doctor. He may just say to wait for your next appointment or he may want to add a med, or reprogram your ICD.
If you have more than 2 shocks close together, or feel really sick like you get dizzy, clammy, or if you get palpitations, you should call an ambulance to bring you to the emergency room. Always tell doctors, surgeons, and dentists treating you that you have an ICD.
If your arrhythmia made you pass out or nearly so, you won’t be allowed to drive for awhile after getting your ICD - for obvious reasons. You can still use most appliances safely, including TV sets, microwave ovens, VCRs, radios and stereo components, kitchen appliances, power tools (unless they are magnetized), and your personal computer.
You should avoid strong electrical or magnetic fields, including electrical power plants, ignition systems, stereo speakers, and magnetic wands like airport security people use. You can walk through metal detector gates but your ICD may set off the alarm; It won’t hurt you or your ICD, though. Avoid arc welding equipment, power generators, MRI scanners, and some medical procedures like electrocautery to stop bleeding or the heat therapy that physical therapists use on muscles. Obviously contact sports are out! Never put a magnet on or near your ICD and keep cell phones 6 inches or more away from the device. That means use your other ear!
ICD Studies

* Guidant Recalls Thousands of Defective ICDs
* Infection Rate With ICD Implant Higher Than Thought
* Device Implant Infections Rising Fast - Increases Risk of Death
* ICDs Vs Drug Treatment Vs No Treatment - The MADIT Trial
* ICDs Vs Amiodarone For Sudden Death Survivors & More
* ICDs Vs Amiodarone - AMIOVERT Trial
* Do ICDs Benefit Heart Failure Patients?
* Contak includes ICD, Dual-Pacer and Heart Booster All In One
* ICDs Safe To Go Through Store Theft Detectors
* ICDs Work Best For Low EF Patients
* Which Heart Failure Patients Really Benefit From An ICD?
* ICDs and DNR Orders - A Dilemma?
* V-Tach Induced During EPS Is A Serious Danger Sign
* ICD Wearers To Send Device Data To Doctor Over Phone Line
* Heart Attack Survivors With Low EF Increase Survival With ICD
* Medtronic Heart Failure Pacemaker With ICD Approved
* Sleep, Breathing, and ICDs
* COMPANION Trial Shows ICD/Pacemaker Benefit in Heart Failure
* ICD Zap Survivors Need Special Monitoring

A-fib Cardioverters

* Implanted Device Uses Magnetism to Stop A-fib
* Implanted Cardioverter For A-fib In Trials

WWW Links

* Zapper
* Sudden Cardiac Death Survivor’s Network - support
* Implantable dot Com
* The Bionic Man
* Zvi Har’El’s page, who has hypertrophic cardiomyopathy & an ICD
* The EP Lab
* Technical ICD info
* MT Desk list of medical device manufacturers

Guidant Recalls ICDs

June 17, 2005 - Guidant has recalled a whole boatload of defective ICDs. See the FDA site, specifically www.fda.gov/bbs/topics/NEWS/2005/NEW01185.html for more information. That page lists the following Guidant devices as being part of this recall, along with more information:

* PRIZM 2 DR, Model 1861, manufactured on or before April 16, 2002
* CONTAK RENEWAL, Model H135, manufactured on or before August 26, 2004
* CONTAK RENEWAL 2, Model H155, manufactured on or before August 26, 2004

The Guidant web site also lists the ICDs in this recall. See www.guidant.com/news/500/web_release/nr_000548.shtml. Here are the ICDs listed there:

* Ventak Prizm 2 DR (Model 1861) ICDs manufactured on or before April 16, 2002
* Contak Renewal (Model H135) and Contak Renewal 2 (Model H155) CRT-Ds manufactured on or before August 26, 2004
* Ventak Prizm AVT, Vitality AVT, Renewal 3 AVT, and Renewal 4 AVT ICDs (All series numbers).

Patients and doctors with questions can call the company at 1-866-GUIDANT.
Implant Infection Rate Higher

August 27, 2001 - Patients with ICDs who get staphylococcus aureus bacteremia may have infected devices also. This risk is much higher than anyone guessed before. Researchers now estimate that about 70% of S aureus bacteremia patients who have an implanted device may also have a device infection.
Dr. Anna Chamis studied 33 patients with ICDs or pacemakers who had S aureus bacteremia over a 6 year period. Device infection was found in 15 of these patients (45%). “The majority of device infections showed no obvious signs,” Dr. Chamis said.
In the 12 patients who had their device implanted within one year of infection, 9 had confirmed device infections; So did 6 patients whose device had been implanted for more than a year. Device infection was suspected in another 9 patients, but these patients died of blood poisoning before tests were completed.
Heart device infection is not always obvious, especially when the infection involves the “pocket” where the device generator is implanted. Sixty percent of the patients with confirmed device infection showed no “detectable signs of generator pocket infection,” the researchers said. Neither physical exam nor an echo can definitely spot this type of infection.
In patients who get S aureus bacteremia, the device is usually involved, and 40% of these patients do show signs of infection. However, in patients who get S aureus bacteremia more than a year after device implant, the device is not usually the source of bacteremia, and there are no signs of device infection - even if the device is infected. The implanted device is involved in about 28% of these patients.
Doctors with patients who get S. aureus bacteremia should worry about device infection, Dr. Chamis said. Device infection results in increased illness and death. If the infected device is not replaced, there is increased risk of death.
If the device becomes infected, it should be replaced, Dr. Chamis said. “If the device is not infected, then the patient should get extended treatment with antibiotics. If test results are uncertain, patients should be closely followed with repeated blood testing.”

Title: Staphylococcus aureus Bacteremia in Patients With Permanent Pacemakers or Implantable Cardioverter-Defibrillators
Authors: Anna Chamis, Gail Peterson, Christopher Cabell, G. Corey, Robert Sorrentino, Ruth Greenfield, Thomas Ryan, L. Reller, Vance Fowler Jr
Source: Circulation 2001;104:1029-1033
Correspondence to Vance G. Fowler, Jr, Box 3281, Division of Infectious Diseases, Duke University Medical Center, Durham, NC 27710. E-mail fowle003@mc.duke.edu
Device Implant Infections Way Up

May 26, 2006 - Risk of infection from device implants has risen much faster than the number of implants in the past 8 years. The risk grew faster for both ICDs and pacemakers. Researchers studied a database of device-related infections. Their study shows that getting an infection from device implant - whether in the device location or myocarditis - increased risk of death 300%.
Most device implant infections happen in the “pocket” where the device actually goes while almost one in five occur as myocarditis. This study used numbers from 1996 to 2003 in the National Hospital Discharge Survey. In 1996 roughly 160,000 devices were implanted and there were about 4000 infections. By 2003, there were roughly 238,000 implants with nearly 13,000 infections. Hospitalizations for device-related infections rose about twice as fast as number of devices implanted. For unknown reasons, being older or female, or both, lowered risk of infection from implant.
Infections are usually “staph” of one sort or another. Many possible reasons for the higher risk of infection were given but none are certain. What is certain is that device implant, and generator/lead replacements carry a risk of infection and this kind of infection raises risk of death. Something to keep in mind.

Source: Heart Rhythm Society 2006 Scientific Sessions
Presenter: Dr Andrew Voigt
MADIT - ICD Versus Drug Treatment

December 1, 1995 - We studied the effect of different treatments on ventricular arrhythmias. Fifty-nine people had an ICD, 53 took anti-arrhythmic drugs and 179 got no arrhythmia treatment. We studied mortality and type of death in these 291 consecutive patients evaluated for heart transplant.
There were 109 deaths (37%) during a 15 month follow-up; 21% were sudden death, 14% non-sudden death, and 2% were not heart-related. Sudden death rate was lowest in the ICD group, intermediate in the no-treatment group, and highest in the drug-treatment group. Anti-arrhythmic drug use was linked to sudden death. ICDs were linked to non-sudden death (pump failure).
Sudden death rates were lowest in ICD patients. Although ICDs reduced sudden death in high-risk CHF patients, the effect on long-term survival was limited, because these patients had high non-sudden death rates.

Title: Influence of the implantable cardioverter/defibrillator on sudden death and total mortality in patients evaluated for cardiac transplantation
Authors: Sweeney MO, Ruskin JN, Garan H, McGovern BA, Guy ML, Torchiana DF, Vlahakes GJ, Newell JB, Semigran MJ, Dec GW
Source: Circulation 1995 Dec 1;92(11):3273-81
Comments in: Circulation 1996 Nov 1;94(9):2308-10 and Circulation 1997 Mar 18;95(6):1666 and Circulation 1997 Mar 18;95(6):1666-7
PMID: 7586314, UI: 96080082
ICDs Versus Amiodarone

November 27, 1997 - Patients who survive life-threatening ventricular arrhythmias are at risk of it happening again. We compared 2 treatments: ICD and anti-arrhythmic drugs. Patients had been resuscitated from near-fatal ventricular fibrillation or had been cardioverted from sustained ventricular tachycardia. Patients also had either fainting spells or other serious cardiac symptoms, and an EF of 40% or less.
One group of patients had an ICD implanted and the other group got class 3 anti-arrhythmic drugs, usually amiodarone (Cordarone). Over the 4 year period, 507 patients got an ICD and 509 took an anti-arrhythmic drug. Forty-five percent had ventricular fibrillation and 55% had ventricular tachycardia. The primary endpoint was overall mortality. Overall survival was higher with ICD than with drug therapy.
ICDs versus Anti-arrhythmic drugs
Follow-up ICD survival Drug survival
one year 89% 82%
two years 82% 75%
three years 75% 64%

Authors; The Antiarrhythmics versus Implantable Defibrillators (AVID) Investigators
Source: N Engl J Med 1997 Nov 27;337(22):1576-83
Comments in: N Engl J Med 1997 Nov 27;337(22):1621-3 and ACP J Club 1998 May-Jun;128(3):60-1
PMID: 9411221, UI: 98026791
ICDs Versus Amiodarone - AMIOVERT

November 25, 2000 - NSVT (non-sustained ventricular tachycardia) is a risk factor for sudden death in patients with DCM not caused by clogged arteries. Figuring out which patients are at risk for SCD is tough. EP studies usually don’t help much in this situation.
Trials such as CHF-STAT and GESICA suggest that amiodarone (Cordarone) may reduce mortality in DCM patients. However, no study has compared amiodarone to an ICD in these patients. The AMIOVERT study tested whether an ICD was more effective than amiodarone for reducing mortality in DCM patients with NSVT.
Patients were randomly assigned to either an ICD implant or 400mg amiodarone twice a day for one week, followed by 400mg amiodarone once a day for 51 weeks, then 300mg once a day. Liver function tests, thyroid function tests, and chest x-rays were closely watched.
The study was stopped early because the endpoint was not going to be reached. Patients not treated were enrolled in a registry.
Outcomes in both groups were similar. There were 72 patients in the amiodarone group and 102 patients in the ICD group. Primary endpoint was mortality at 2 years. Secondary endpoints included cause of death, arrhythmia-free survival, cost, and quality of life. All patients had an EF less than 36%, NSVT without symptoms, and class one to class 3 CHF.
There were 8 deaths in the amiodarone group and 13 in the ICD group. Arrhythmia-free survival was better in amiodarone patients than in ICD patients (arrhythmias are stopped with an ICD, not prevented). This study did show that in DCM patients with a low EF and NSVT, overall mortality at 4 years is the same whether the patient is treated with amiodarone or an ICD.

Source: American Heart Association Scientific Sessions 2000
Title: Amiodarone vs Implantable Defibrillator in Patients With Nonischemic Cardiomyopathy and Asymptomatic Nonsustained Ventricular Tachycardia
Author: Dr. S. Strickberger
Do ICDs Benefit CHFers?

October, 1998 - Do heart failure patients get benefit from an ICD? We studied whether heart class was related to benefit from ICDs. We studied data stored in the memory of ICD software.
Between 1989 and 1996, 603 patients used an ICD that “remembers” EKGs taken by the ICD during an episode. Seventy-seven percent of these patients were men, 59% had coronary artery disease and 16% had DCM. Their average age was 57 years and their average EF was 44%.
We studied the link between heart class at ICD implant to overall mortality and recurrence of arrhythmias. The benefit was defined as the difference between mortality and the hypothetical death rate if the device had not been implanted.
A significant difference between hypothetical death rate and overall mortality was seen (14% at 1 year, 24% at 3 years, and 27% at 5 years). This suggests a benefit from ICDs in people with heart failure.
Link between heart class and ICD benefit in CHFers
Follow-up Heart class at implant Benefit from ICD - Risk of death lowered by:
class one one year 15%
class one 3 years 29%
class one 5 years 36%
class 2 to class 3 3 years 22%
class 2 to class 3 5 years 23%

Even class 3 patients with a history of decompensated heart failure benefited from an ICD. Stored EKG data shows that in patients with a history of ventricular tachycardia or ventricular fibrillation, an ICD may prolong life in class 1, class 2, and class 3 patients. The benefit is greatest in class 2 and class 3 patients at first but benefit may last longest in class one patients.

Title: Potential benefit from implantable cardioverter-defibrillator therapy in patients with and without heart failure
Authors: Bocker D; Bansch D; Heinecke A; Weber M; Brunn J; Hammel D; Borggrefe M; Breithardt G;
Source: Circulation 1998 Oct 20;98(16):1636-43
PMID: 9778329 UI: 98451630
ICDs Are Safe Going Through Detectors

July 26, 1999 - People with ICDs can safely walk through electronic anti-theft systems. The anti-theft machines use an electronic beam to spot security-tagged merchandise being carried out of a store. Some people worried that an ICD might interpret the electronic beam as a rapid heartbeat, triggering a zap from the ICD.
Dr. Douglas Zipes, the study’s author says, “There is absolutely no danger from a slow stroll through the gates, even if it takes 10 seconds.” In the study, one person even went through in a walker without any problems. “A person should not lean on, or linger in between, theft detection devices; but in normal use there is nothing to worry about,” says Zipes.
“We tried to duplicate a normal situation of someone shopping and just passing through the machines,” he says. In tests on 169 ICD wearers, they found no problems from a normal 10 to 15 second walk through the security gates. The researchers used a magnetic programmer tool to prevent shocks during the tests. Although the devices continued to record data so it was known whether a shock would have been delivered, the shocking mechanism was turned off. “When an ICD fires, it is like a mule kick in the chest. It’s not pleasant,” Zipes explains.
When the patients received a lot of exposure by standing within 6 inches of the transmitter pole for 2 full minutes, 19 of the 169 people had ICD interference. Seven of those episodes would have delivered shocks, Zipes says.
This is in line with an FDA letter of 1998, which said that although the anti-theft machines seemed safe, patients should not lean on or linger in the machines. That same letter advised patients being scanned with hand-held metal detectors like those used in airports, to warn security personnel that they have an ICD and to ask them not to hold the metal detector near the device any longer than necessary. (Jon’s note: Always carry your ICD wallet card with you!)

Source: Circulation 1999;100:387-392
ICDs Best For Low EF Patients

October 4, 1999 - Survivors of life-threatening arrhythmia face a high risk of another fatal episode, according to Dr. Michael Domanski, from the AVID study. The report says that an ICD works better than anti-arrhythmic drugs to improve survival of patients whose EF is less than 35%.
Patients with an EF higher than 35% did no better with an ICD than with drug treatment, but those with an EF below 35% had significantly better survival with an ICD than with drug therapy. Patients with an EF below 20% however, had only a 2 to 3% survival advantage with an ICD versus drug therapy.

Source: Journal of the American College of Cardiology 1999;34:1090-1095
Who Really Benefits From An ICD?

March 21, 2002 - ICDs prolong survival in patients with ischemic cardiomyopathy and a positive EPS. The MADIT II trial tested whether ICDs prolong survival in another patient group: those with prior heart attack and ejection fractions under 30%, but who have not had an EPS.
1,232 such patients were randomized in a 3 to 2 ratio to either ICD or standard drug therapy. Follow-up was 20 months. The mortality rate was much lower in the ICD group (14.2%) than in the drug group (19.8%). No ICD patients died. ICD patients did have more worsening heart failure (19.9%) than drug-only patients (14.9%).
Notably, EPS was not used to identify high-risk patients. The results suggest that ICDs should be considered for all patients with ischemic cardiomyopathy. The precise reason for increased heart failure hospitalizations in the ICD group and cost-effectiveness need further study.

Title: Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction
Authors: Moss AJ, et al
Source: N Engl J Med 2002 Mar 21; 346:877-83 and
Title: Expanding indications for implantable cardiac defibrillators
Authors Bigger, JT
Source: N Engl J Med 2002 Mar 21; 346:931-3
Do Not Resuscitate & ICDs

April 17, 2000 - ICDs are becoming more common, and so are patients’ who don’t want to be resuscitated when they die. Should doctors assume that a patient with a DNR (Do Not Resuscitate order) wants his ICD deactivated? Consider the case of a 66 year old man with DCM and serious arrhythmia.
He was brought to the hospital with a massive stroke and congested lungs. He was sent to the intensive care unit. One year before this, he had suffered sudden cardiac death, and had an ICD implanted. The patient did not improve. Permission to write a DNR order was obtained from the patient’s family. Only after the family left the hospital did the doctors realize that the patient was not to be resuscitated, but would be automatically revived by the ICD if a lethal arrhythmia occurred. Did the family’s consent to the DNR order mean the ICD should be deactivated?
A patient’s DNR order is a refusal of CPR. In general, it is wrong to assume that it includes anything else. In the case of an ICD however, the treatment in question is electrical defibrillation, which is in the same category as CPR.
The ICD was already in use when the DNR order was written. To understand why this matters, let’s consider the ventilator. The patient was placed on a ventilator for lung congestion. The family might reasonably expect that since the patient was already on a ventilator when the DNR was written, he would stay on the ventilator. Therefore the family might reasonably expect that since the ICD was functioning when the DNR was written, it would stay turned on.
Also, the ICD is an internal device and may be said to be part of the patient. In this way, it is different from an external defibrillator, or even the hands of a doctor performing CPR. The question is, “Has the ICD become a part of the patient or is it just another form of CPR?” If the ICD is just another form of CPR, it should be turned off and there is no reason to tell the family. On the other hand, if the ICD is now part of the patient, then the DNR order does not allow us to turn off the ICD.
Although the ICD is firmly imbedded inside the patient and its removal would damage the patient (surgery would be required), the ICD does not have to be removed to be deactivated. We believe the ICD falls into that gray area between being a part of the patient - like a transplanted organ - and being just another medical treatment. Thus, the patient should decide. So consenting to a DNR does not authorize a doctor to deactivate an ICD without a specific order to do so.
As implanted devices become more common, doctors will run into these issues more often. Doctors must discuss these issues with their patients who have implanted devices. Doctors must encourage those patients to express their views in advance directives.

Title: Deactivating the Implantable Cardioverter-Defibrillator: A Biofixture Analysis
Author: Frederick Paola and Robert Walker
Source: South Med J 93(1): 20-23, 2000
Inducible Tachycardia A Danger Sign

June 30, 2000 - During an EPS, a doctor uses a catheter tool to make your heart go into an irregular rhythm. If he succeeds, it means you are at higher risk for having it happen at any time. If he cannot cause (induce) an irregular rhythm, you may not be at high risk for an arrhythmia episode.
Most sudden deaths result from ventricular tachycardia (VT) or ventricular fibrillation (VF). Researchers in the USA and Canada studied more than 1,700 patients. Of those patients, 353 had inducible VT and 1,397 did not. The patients were followed for over 3 years.
Inducible versus Non-inducible VT
Patient group Follow-up Risk of cardiac arrest/death All-cause mortality
with inducible VT 2 years 18% 28%
without inducible VT 2 years 12% 21%
with inducible VT 5 years 32% 48%
without inducible VT 5 years 24% 44%

Patients had coronary artery disease, an EF of 40% or less and spontaneous, unsustained ventricular tachycardia. Results show that “inducible” sustained VT identifies patients at much higher risk for sudden death, the authors conclude. These patients may be candidates for ICDs.

Source: N Engl J Med 2000;342:1937-1945
Online Network For ICD Wearers

January 2, 2002 - Medtronic has received FDA approval for their CareLink Network. This system allows an ICD wearer to transmit his ICD data straight from his device to a doctor over a regular phone line.
The ICD wearer has a wand that looks like a computer mouse connected by a wire to a small console - this is called the monitor. You push a button on the console, then wave the wand over your ICD. The wand collects data from your implanted device and transfers it to the console automatically through the wire. The console then automatically dials a toll-free phone number and sends the data to the Network over a regular phone line.
Doctors get their patients’ data by logging onto a doctors’ web site. Patients can view their information on a personalized web site. At first, only patients with GEM II DR/VR ICDs will be involved. However, the network is designed to support many other devices, including pacemakers. Existing implanted devices work with this system - no changes or adjustments are needed.
Medtronic will sell patient monitors and software packages to doctors, and will charge a fee for each use of the network. Patients may have to pay a fee. Doctors may be able to bill patients’ insurance companies the cost of a follow-up visit each time they access patient data. Ten pilot sites will start the network.
The monitor is portable so it can be used when traveling as long as a standard USA phone line is available. The network will also provide data management for other health information. Medtronic is trying to protect confidentiality and security by requiring registration and passwords to access the web sites.
Jon’s notes - Will they really keep this info secure? I have no idea. Big-name sites that depend on e-commerce to survive have not mastered online security so I wonder how secure this venture can really be. I would definitely not want my health care information online, especially if I improve enough to go back to work. Once your medical history is out in the open, there is no way to regain its confidentiality, ever, period.
Billing insurers for online accesses to patient information opens up a delightful source of fraud. Can Medtronic keep this under control? I doubt it, but will wait and see. This is a truly wonderful idea that is going to be very, very tough to keep legitimate and secure.

Sources: Reuters, AP, Medtronic’s press releases
Risk After MI Reduced By ICD

March 19, 2002 - Heart attack survivors with low EF can reduce their risk of death by 31% with an ICD implant. The MADIT-II trial results were presented at the American College of Cardiology 51st Scientific Session. The study enrolled 1,232 patients who had suffered at least one MI and had an EF of 30% or less.
742 patients had an ICD implanted plus got drug therapy, while the rest were managed with drug therapy alone. During an average follow-up of 20 months, mortality in ICD patients was 14.2% compared to 19.8% for non-ICD patients. That is a relative risk reduction of 31%. Mortality from arrhythmia was 3.6% in ICD patients and 9.4% in the drug group.

Source: Reuters Health
ICD + Pacemaker Approved For CHF

July 5, 2002 - The FDA has approved Medtronic’s InSync ICD system. It combines an ICD with a heart failure pacemaker (CRT therapy). The implanted device synchronizes the heart beat and can slow a fast heart rate, as well as deliver a shock to stop dangerous irregular beats.
A similar device by Guidant was approved in May. Medtronic’s device supposedly uses fewer shocks to slow a rapidly beating heart.

Source: AP
Magnetic ICDs To Stop A-Fib

January 15, 1998 - In Control, Inc., announced today that Dr. Steven Kutalek implanted a Metrix atrial defibrillator in a 42-year old man. James Gamble suffered from a-fib, which is an irregular heart rhythm that can lead to strokes. A-fib causes fatigue, shortness of breath, and dizziness in many people. Drugs did not relieve his symptoms. Now when Mr. Gamble feels a-fib, he can pass a magnet over his chest to trigger the new device, which will return his heart to normal rhythm.
“A-fib episodes are not life threatening, but they can drive you nuts, keeping patients from doing day-to-day activities,” explained Dr. Kutalek, “The larger concern is that chronic a-fib can lead to stroke,” he said. People with a-fib are about 5 times more likely to have a stroke than healthy people.
Until now, treatment for a-fib was drugs, often used with external cardioversion - an electric shock given with paddles like you see on tv shows. The Metrix device can spot a-fib and deliver an electric shock to restore normal rhythm, or the patient can trigger the unit himself by passing a special magnet over his chest when he begins to feel symptoms.

Author: Sue Morgan
Source: Allegheny News
Atrioverter In Trials

1998 - This article is about an implanted device that converts a-fib to normal rhythm with low-energy shocks. The trial included 51 patients. The device was the InControl Metrix Atrioverter system. This is an implanted device with 3 leads - right atrial and sinus leads, and a ventricular pacing lead. After being implanted, the devices were set in monitoring mode. A doctor delivered the shocks while the patient was hospitalized during the trial.
Average follow-up was 259 days. A total of 3,719 shocks were delivered: 3,049 during testing and 670 for spontaneous a-fib episodes. The detection software was 100% correct in recognizing normal rhythm and 92% correct recognizing a-fib.
The device converted 96% of the episodes. Ten episodes could not be converted. Early recurrence of a-fib was defined as the return of a-fib within one minute after a shock that successfully converted rhythm to normal. This happened in 51% of patients. The device was safe.
By the end of follow-up, all but 3 patients were on drug therapy, mostly sotalol or amiodarone. Complications included vein blockage in 2 patients. Four patients required repositioning of a lead. Two patients developed infection, requiring removal of the device and leads.
Conclusion: The atrioverter recognizes arrhythmias. It was effective in converting a-fib, restoring 74% of episodes to normal rhythm by itself. Overall effectiveness of the device was 86%. Early recurrence occurred in 27% of shock episodes. This may be a problem outside the hospital setting. The success of the device will ultimately lie in the ability of patients to handle the shocks without sedation, especially if more than one shock is required for success.

Title: Atrioverter: An Implantable Device for the Treatment of Atrial Fibrillation
Authors: Wellens J, Lau CP, Luderitz B, Akhtar M, Waldo AL, Camm AJ, Timmermans C, Tse HF, Jung W, Jordaens L, Ayers G
Source: Circulation 98:1651-1656, 1998
Sleep, Breathing, and ICDs

August 28, 2002 - Sleep-related breathing disorders may raise the risk of arrhythmias in some people with ICDs. Dr. Joachim Fichter did a sleep study of 38 patients. All had weak hearts with reduced ejection fractions, averaging 36%. All also had life-threatening too-fast ventricular arrhythmias and ICDS.
Sleep-related breathing disorders were diagnosed in 14 patients. Of these, 8 showed Cheyne-Stokes respiration and the remaining 6 had obstructive sleep apnea.
Monitoring showed that 4 of the Cheyne-Stokes patients and 4 of the sleep apnea patients had ventricular arrhythmias during sleep. It was also showed that arrhythmias during episodes of disordered breathing were worse than during normal breathing.

Source: Chest 2002;122:558-561
The COMPANION Trial

March 31, 2003 - Implanting a combination ICD/CRT pacemaker in heart failure patients on best drug therapy reduced all-cause mortality 43%, according to the 1,634 patient COMPANION study. “We saw that 43% reduction on top of best drug therapy. We are also getting fewer hospitalizations,” said Dr. Michael Bristow, trial co-author.
Best drug therapy was defined as a beta-blocker, ACE inhibitor, and Aldactone (spironolactone). Dr. Bristow thinks that when a cost analysis is done, this will be cost-effective because it reduces hospitalizations. Patients who got either a CRT pacemaker or a CRT pacemaker with ICD “had 35% fewer hospitalizations for any cause and 39% fewer hospitalizations for heart failure.” Of the patients enrolled in the study, 55% “had ischemic heart disease and the effect was the same in those patients,” Dr. Bristow said.
Dr. Jon Kobasigawa said, “This may be a quality of life issue. If the device can reduce hospitalizations, it may significantly improve quality of life for these patients.” Dr. Kobasigawa added that devices are expensive, adding $20,000 or more to the cost of treatment.
Dr. Bert Pitt said he “didn’t think you can make the case for cost-effectiveness when we can significantly reduce symptoms and risk of death with drug therapy.” Dr. Pitt added that eplerenone treatment “costs pennies compared to an ICD. I could throw pills at patients all day and it still wouldn’t add up to the money spent on these devices.”
Dr. Bristow countered that Dr. Pitt’s trial studied “a different population. Those were post-heart attack patients rather than chronic advanced heart failure patients.” Dr. Bristow added that he isn’t presenting a case for devices instead of drug therapy but added to heart failure drugs.

Source: ACC 52nd Annual Scientific Sessions; Medscape
ICD Zap Survivors Need Monitoring

December 21, 2004 - Researchers analyzed data from the MADIT-II trial to study long-term prognosis of patients who got life-saving zaps from their ICDs. Of 720 patients with an ICD (average follow-up 21 months), 169 patients received 701 needed ICD zaps. Probability of surviving at least one year after first ICD zap for either ventricular tachycardia (VT) or ventricular fibrillation (VF) was 80%.
Compared to those who did not get any zaps from their ICD, people who were zapped were 3 times more likely to have heart failure episodes or die from pump failure - worsening CHF. This study shows that successful appropriate ICD shocks for VT or VF are associated with 80% survival one year later. These patients are at increased risk for heart failure and non-sudden cardiac death (pump failure) after successful ICD zaps.
Patients who get ICD shocks should receive special attention to prevent and manage worsening left heart failure during long-term follow-up.

Title: Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator.
Authors: Moss AJ, Greenberg H, Case RB, Zareba W, Hall WJ, Brown MW, Daubert JP, McNitt S, Andrews ML, Elkin AD. E-mail: heartajm@heart.rochester.edu
Source: Circulation. 2004 Dec 21;110(25):3760-5. E-published 2004 Dec 6.

Implantable Cardioverter Defibrillator (ICD)

The Implantable Cardioverter Defibrillator (ICD) is a device placed in your body to help control your heart rhythm (the speed and pattern of your heartbeat). This rhythm is set by signals from the heart’s electrical system. A problem with these signals can cause your heart to beat too quickly, too slowly, or irregularly. This is called an arrhythmia.

Some symptoms of a fast heart rhythm may include:

* Palpitations (a fluttering, fast heartbeat) Dizziness or Lightheadedness
* Fainting Spells
* Weakness
* Warm, Flushed Feeling

A heart rhythm problem can stop the heart from pumping blood. This is called cardiac arrest and can be life threatening. (Note: Cardiac Arrest is not the same as a heart attack. A heart attack is when a blood vessel to the heart muscle is blocked.)

You may be given an ICD if you have had a cardiac arrest or if you have a fast heart rhythm problem that could lead to cardiac arrest. The ICD is not a cure for your heart rhythm problem. It can save your life by quickly bringing a dangerously fast heart rhythm under control. You will need an ICD for the rest of your life, so having one implanted means a lifelong commitment.

Problems with electrical signals can cause very fast heart rhythms. Two common types of heart rhythms are Ventricular Tachycardia (V-Tach) and Ventricular Fibrillation (V-Fib). Both can lead to cardiac arrest, so an ICD is usually needed.

With ventricular tachycardia, a ventricle contains a group of abnormal electrical cells called a circuit. The circuit sometimes sends out signals that make the lower chambers beat very fast. The chamber don’t have time to fill with blood before the next beat. So, the heart pumps less blood than the body needs, causing your symptoms. V-Tach can progress to a more serious arrhythmia, V-Fib.

With ventricular fibrillation, abnormal circuits in the ventricles sometimes send signals quickly and irregularly. The heartbeat can be so fast and uneven that the heart muscle quivers rather than pumps. A quivering heart is in cardiac arrest. Emergency treatment must be given to get the heart pumping again, or death may result.

V-Tach and V-Fib usually develop in damaged heart muscle. This damage may be caused by:

* A scar on the heart muscle from a heart attack
* Cardiomyopathy, which is a diseased, weakened heart muscle
* Other problems, including heart valve problems and congenital (present at birth) heart problems

Sometimes a heart rhythm problem can exist even though the heart muscle hasn’t been damaged. This is called a primary electrical problem. An Implantable Cardioverter Defibrillator (ICD) can help.

An ICD is a small, lightweight electronic device that is place inside your body. It keeps track of your heart rhythm. When you have an arrhythmia, the ICD helps your heart return to its normal rhythm. An ICD can do one or more of the following:

* Antitachycardia pacing (ATP): The ICD can send out a series of pulses to override a fast rhythm. This may feel like fluttering in your chest, or may not be felt at all.
* Cardioversion: If ATP doesn’t slow a fast rhythm, the ICD can give the heart one ore more small shocks. These break up the fast rhythm. They may feel like thumps in your chest.
* Defibrillation: If the ICD senses a very fast, irregular rhythm, it quickly sends a strong shock to the heart to override the fast rhythm. You may feel this as a strong kick in your chest.
* Bradycardia Pacing: An ICD’s main job is to slow a fast heart rhythm. At rare times, your heart may beat to slowly.This may happen if you have a second heart rhythm problem that causes a slow heartbeat. Your heart may also beat too slowly after an ICD shock. Most ICDs can send out pulses to get a slow heartbeat back to the right speed.

Inserting the ICD into your body is called implantation. ICD implantation is not open heart surgery. Rather, it’s a minor procedure that’s done in an operating room or cardiac catheterization lab. You’ll be given instructions on how to prepare for the procedure. The ICD can be inserted near the right or left shoulder. If you prefer to have it implanted on a particular side, discuss your preference with your doctor.

Ask your doctor whether you should stop taking aspirin or other medications before your procedure. Unless instructed otherwise, don’t eat or drink anything for six hours before the procedure. Before the procedure begins, you may be given some medication to help you relax. This medication will help you “sleep” through part or all of the procedure, so you won’t feel pain. The skin where the pacemaker is to be implanted will be washed and shaved.

An incision is made in your skin below your collarbone. For an abdominal implant, a second incision is also made below your ribcage. A small “pocket” (space) is made under your skin or muscle for the ICD generator to sit in. For the abdominal implant, the pocket is made near the incision below the rib cage.

The lead for the ICD is threaded through the incision into a vein in your upper chest. The lead is then guided into your heart’s chambers using x-ray monitors. Electrical measurements are taken to determine a good position for the lead in the heart. For an abdominal implant, the other end of the lead is threaded under the skin from the chest to the abdomen.

The ICD generator is attached to the lead. Then, the generator is placed in the pocket under your skin. The ICD’s settings are programmed to treat your heart rhythm problem. The incision is then closed and covered with a sterile dressing.

(Note: A patch electrode is sometimes also used to help the ICD do its job. If one is needed, your doctor will make another incision to place the patch under the skin or muscle near your heart. A lead connects the patch to the generator.)

In rare cases, the ICD may be implanted through open chest surgery. this may be done along with open chest surgery for another heart problem, or if problems keep the leads from being placed in the veins. The chest is opened and the leads are attached to the outside of the heart. The generator is placed in a pocket in the abdomen.

After your ICD is implanted, you’ll probably stay in the hospital for a day or two. Before you go home, you will be told how to take care of your incision site or sites as they heal. You may have some tests. You’ll also have some follow-up visits scheduled.

During your stay in the hospital, your heart’s signals are monitored to be sure the ICD is working right. A nurse may take your pulse and blood pressure and check your incision for bleeding or swelling. Before you go home, an x-ray of your chest may be taken. The ICD settings may also be rechecked. This is done from outside your body. For a week or so, it’s normal to have some pain and stiffness around your incision. Pain medication can help make you more comfortable. Don’t raise the arm on the side of the incision above your shoulder. This will give the lead a chance to secure inside the vein and your heart. Be sure to tell your nurse if you feel any unusual symptoms like hiccups that won’t go away, dizziness, chest pain or shortness of breath.

At home, you can go back to most of your daily activities. But take it easy for a month or so to avoid pulling the lead or leads out of place. For a few weeks, you may feel numbness or fullness in the area around the ICD. This is normal.

* Visit the doctor, usually in a week or so. During this visit, the doctor may remove your sutures or staples, if you have them.
* Avoid raising the arm on the side of the ICD over your head. Your doctor will tell you for how long - usually 2 to 6 weeks.
* Ask your doctor when you can return to activities like heavy lifting, running, or contact sports.

Your incision should heal completely within about a month after the implantation. You may feel and see a small bump under your skin where the ICD is. This won’t be noticeable under your clothes. Even after you heal, avoid playing with the ICD under your skin. If you take medications for your heart problem, keep taking them as directed. Talk to your doctor about driving. In some cases, driving may be restricted. This would be due to your heart rhythm problem, not the ICD.

Call your doctor if you notice any of the following:

* Signs of an infection (a fever over 100 degrees F; redness, swelling or warmth at the incision site; drainage from the incision)
* Twitching chest muscles
* Increasing pain around your ICD
* Bleeding from your incision
* Swollen arm on the side of the incision site

To be sure your ICD is working right, you’ll need to visit your doctor or clinic several times a year. During these visits, the ICD’s record is checked and the ICD’s settings can be changed, if necessary. The settings can be changed from outside your body, without the need for surgery. You may still feel symptoms when you have a fast heart rhythm, but your ICD will stop them. If you do feel symptoms, follow your doctor’s advice on what to do next. Tests such as an ECG may be performed. Your ICD’s battery will also be checked. ICD batteries last 3 to 7 years. Your doctor will know well in advance when the battery needs to be replaced. The battery won’t run down unexpectedly.

When you have an event, you may feel your usual symptoms of a fast heart rhythm. If you do, find a place to sit or lie down. Put your feet up. If possible have someone stay with you for about 15 minutes. You won’t always feel the ICD working. Low-energy pulses may be enough to slow your heart rhythm. If a shock is needed, though, you will feel it. It may feel as light as a thump or as strong as a kick to the chest. Whether you feel it working or not, you can rely on your ICD to treat you when you need it. Very rarely, a person with an ICD may need additional medical care. Know what to do if this happens.

If you have an event and feel okay afterward, let your doctor or nurse know. (This is not an emergency, so call during business hours.)

When to Call 911 (Emergency)

* You still feel symptoms after a shock
* You feel 3 or more shocks in a row
* Your symptoms don’t away and you feel no shock

[Note: If you have a very fast, irregular heart rhythm, your blood pressure will drop sharply and you may pass out. Your ICD will soon slow the heart rhythm and you’ll wake up. A friend or family member should call 911 (emergency) if you stay unconscious for more than 30 seconds.]

An ICD won’t keep you from living an active life. You can usually do almost everything you did before you got your ICD, and since you will probably feel better, you may do even more!

When you first get your ICD, you’ll be given an ID card to carry. This ID card contains important information about your ICD. It also tells others what to do in an emergency. Show it to any doctor, dentist, or other medical professional you visit. Also, because pacemaker tend to set off security devices like those found in airports and libraries, you may need to show your card to security personnel. Hand-held security wands (such as those in airports) may affect your ICD. Show your card to avoid this type of scan. You should get an ID bracelet or necklace saying you have a heart rhythm problem and an ICD. Ask your doctor or nurse for your rate cutoff - the heart rate at which your ICD begins treatment. Other healthcare providers may ask you for this number.

ICD’s are well protected from outside signals, so there are very few things that can interfere with your pacemaker. But if you ever feel symptoms that make you think a device is disrupting your ICD’s signals, turn the device off or move away from it. Your symptoms should stop and your ICD shouldn’t be damaged. To be safe, check with your doctor.

Appliances which should be safe to use include:

* Microwave ovens and other appliances in good repair
* Computers
* Hair Dryers
* Power Tools
* TV’s and Radios
* Stereos
* Electric Blankets and Heating Pads
* Vacuum Cleaners

There are a few things to avoid that might interfere with your ICD. These include very strong magnets (like those used for an MRI or in hand-held security wands), radio transmitting tours, ham radios, certain surgical instruments and cellular phones. When using a cellular phone, hold it on the ear farthest away from your pacemaker. Don’t carry it in your breast pocket, even when it’s turned off. Also, a running car engine generates an electrical field, so avoid leaning directly over the open hood of a running car.

With an ICD, you’ll know that your heart rhythm problem can be managed. Now you can live your life to the fullest. Talk to your doctor about exercise and ask whether there are any activities you should avoid. Take care of yourself and see your doctor regularly to ensure that you stay healthy and feeling good!

Cathy Olig, RN, BS
Lead – Electrophysiology and Pacing

Why is the doctor performing this procedure?

Studies have shown that there are categories of patients with cardiac disease that are at high risk for heart rhythms that are very fast and can cause syncope (fainting) or threaten your life. In some cases, an electrophysiologist may have done an electrophysiology study to determine if you are at an increased risk to have these heart rhythms.

These rhythms are called ventricular tachycardia or ventricular fibrillation.

Ventricular tachycardia is a fast heart rhythm that starts in the main pumping chambers of the heart called the ventricles. In ventricular tachycardia, the heart beats at such a rapid rate that the heart does not have time to fill with the blood that is returning from the rest of the body. In addition, because the rate is so fast, the heart cannot effectively pump oxygenated blood back out to the head and major organs. A patient in ventricular tachycardia may quickly lose consciousness as the body is deprived of life-giving oxygen. A patient in ventricular tachycardia may die without immediate treatment.

Ventricular fibrillation is disorganization of the contraction of the heart muscle, making the heart unable to pump blood to the body. Patients in ventricular fibrillation lose consciousness almost immediately and may die if a normal heart rhythm is not quickly restored.

What is an Implantable Cardioverter Defibrillator (ICD)?

An ICD is a system with two main parts:

1) The pulse generator is a smooth, lightweight, metal case that contains a battery and small computer. It continuously checks your heart’s electrical signals. The memory in the pulse generator stores information about your heart’s activity as well as the status of the ICD battery.

2) The leads are insulated, flexible wires which are positioned in the heart and are connected to the pulse generator.

There are several different ICDs. You may receive a one, two or three lead system. Your electrophysiologist will discuss your treatment plan with you prior to the procedure and review the lead system that will best meet your needs.

When is an Implantable Cardioverter Defibrillator (ICD) indicated?

Studies have shown that there are people who are at risk for extremely fast heart rhythms. In general, patients with a heart muscle that has been damaged and is not able to pump effectively are at higher risk for rapid heart rhythms. The damage may be due to a heart attack, or some other disease process. There are also rare genetic conditions that may make a person at risk for life threatening rhythms.

Some patients have already been diagnosed with these fast rhythms and have experienced a near death experience. Others may have an Electrophysiology Study to determine if the patient is prone to developing fast rhythms. Recent studies have shown that some cardiac diseases increase the risk of developing fast rhythms. Your cardiologist may recommend an ICD as prophylactic treatment in case you have a fast rhythm.

An implantable Cardioverter Defibrillator is designed to continuously monitor your heart rhythm. If a dangerously fast heart rhythm is detected, the device will immediately treat the rhythm and deliver therapy to return your heart to a normal rhythm. Treatment may include either rapid pacing of your heart to break the rhythm, or a shock to reset the heart’s electrical system.

In addition, most Implantable Cardioverter Defibrillators contain pacemakers. They may be programmed to pace your heart on a regular basis or they may only provide pacing if your heart rate slows dramatically. Your electrophysiologist will determine the best settings for your clinical needs.

What happens during implantation of an Implantable Cardioverter Defibrillator (ICD)?

Most ICDs are implanted in the Electrophysiology Lab using a local anesthetic and medication to help you relax. Occasionally, a patient may require general anesthesia if their medical condition warrants. The decision regarding using anesthesia will be made by your electrophysiologist. For uncomplicated implants, the patient generally stays in the hospital overnight and goes home the day after the procedure.

Patients will have an incision approximately 3 inches long just under their collar bone (clavicle). The ICD will be placed under the tissue above the pectoral muscle. You may possibly see the outline of the device and may even feel it by pressing on your skin.

Implantation of an ICD takes from two to six hours depending on the lead system selected and the anatomy of the patient.

On the day of the procedure, you will be asked not to ear to drink anything after midnight.

If you have hair on your chest where the device will be placed, the staff will clip the hair to help prevent infection. You will also receive an antibiotic in your IV. The area where the physician will work will be painted with a solution that kills bacteria.

You will receive medication in your IV to help you relax. Most patients sleep through the procedure and have few memories of the surgery. During the procedure, your heart rhythm, blood pressure and the oxygen in your blood will all be continuously monitored.

You will be draped and your face will be covered for a short time. The doctor will numb the area where the ICD will be implanted. You may feel pressure in the area, but you should not feel pain. Please tell the staff if you are having any pain. It is their goal to be sure you are comfortable during the procedure.

After the incision, the physician will make a small opening under tissue below your skin. This is called a “pocket” and the ICD pulse generator will be placed in it. The physician will then use the subclavian vein, which runs near the collarbone (clavicle) to place the leads in to your heart. The leads are positioned in the appropriate chambers of the heart. The ICD will then be connected to the leads and tested to make sure it is properly functioning.

The incision will be closed and you will be allowed to wake up. Once awake, you will be returned to your room and may eat and drink.

In some instances, the testing of the device will be done by bringing you back to the lab some time after the procedure. If the test is done at a later date, the electrophysiologist will test the device by using a programmer to talk to your ICD. A small, specially designed wand will be placed over the ICD to allow a computer to communicate with the device. You will be asleep during the procedure and may not have a memory of it.

What should I do if I receive a shock?

If you receive one or two shocks, and are feeling fine, notify your electrophysiologist or the Pacemaker/ICD clinic the next business day. They will schedule a time for you to come in and will interrogate your ICD to review what was happening in your heart to cause the device to deliver therapy.

If you receive three or more shocks, you should call 9-1-1 and go to the nearest emergency room. DO NOT DRIVE YOURSELF TO THE HOSPITAL.

Special Instructions for Implantable Cardioverter Defibrillators (ICDs)

* MRI is contraindicated for patients with Implantable Cardioverter Defibrillators. You may have a CT scan.
* Please carry your ICD identification card with you at all times.
* Wear a medic alert bracelet or necklace. If you are unconscious, emergency health care professionals will know that you have an ICD that treats life threatening heart rhythms.
* If you use a cellular phone, use the phone on the opposite ear from the pulse generator. You should, also, not carry cell phones in a pocket directly over your ICD. This only applies to cellular phones and not to cordless phones you may have in your home.
* It is safe to walk through the theft detection devices at stores, but you should not stand in or near them for more than a few seconds.
* The electrophysiologists at Meriter Hospital do not routinely prescribe prophylactic antibiotic therapy for routine dental visits.
* If you have questions, please talk to your electrophysiologist.

Airport Safety

* You may walk through the metal detector at the airport without harm, but do not stand in the metal detector for more than a few seconds.
* Carry your ICD identification card with you so that airport security knows you have an ICD.
* Airport security may use the wand on you, but they should not hold it over the area of the pulse generator (ICD) for more than a few seconds.
* Avoid standing near the metal detectors at the airport.

Do Implantable Cardioverter Defibrillators (ICDs) wear out?

The ICD pulse generator runs on a battery and will eventually need replacing. The length of time the battery lasts is dependant on several factors:

* The type of device you received
* The amount of time the ICD is used to pace your heart
* The amount of energy that is needed to pace your heart
* How often you have received therapy for fast heart rhythms

The Pacemaker/ICD Clinic can estimate the amount of time left on the battery when they check the ICD in the clinic. The device has protective mechanisms built in to the programming to allow plenty of notification that the battery needs replacing. The Pacemaker/ ICD Clinic will let you know at your clinic visits that the battery is starting to get low, so that you can plan when to have it replaced.

To change the battery on an Implantable Cardioverter Defibrillator, the entire pulse generator has to be replaced. Most patients are discharged from the hospital the same day as the procedure.

You will be brought to the Electrophysiology Lab and prepared as if you were having a new implant. The cardiologist will numb the skin and make an incision at the site of the pulse generator. The old generator will be removed and the staff will assist the physician in checking the lead system to be sure it is still working well. Then a new pulse generator will be connected to the leads and placed back in the pocket. The cardiologist may decide to test the device, just as it was tested at the original implant. The suture line will be closed and you will be returned to your room.

Because changing the battery does not usually require the placement of new leads, the procedure is generally quicker. Typically the procedure takes 2 hours or less.

What is an Implantable Cardioverter Defibrillator ICD?

Some patients have very fast heart rhythms that may cause loss of consciousness or even sudden death.

These serious rhythm disturbances may be treated with an implantable cardioverter-defibrillator (ICD).

ICD devices are larger than pacemakers but, like them, consist of wires leading to the heart and a separate generator box implanted in a pocket under the skin. When the ICD detects a serious heart rhythm problem, it may deliver an electrical shock to the heart to restore normal rhythm. Some ICD’s can function as a pacemaker as well.

Shocks delivered when someone is awake may be painful, but lifesaving. A person touching you will not be shocked. Patients with an ICD should discuss the safety of driving a car with their doctor.

Procedure Overview

What is a pacemaker/implantable cardioverter defibrillator (ICD) insertion?

A pacemaker/implantable cardioverter defibrillator (ICD) insertion is a procedure in which a pacemaker and/or an ICD is inserted to assist in regulating problems with the heart rate (pacemaker) or heart rhythm (ICD).

Pacemaker

When a problem develops with the heart’s rhythm, such as a slow rhythm, a pacemaker may be selected for treatment. A pacemaker is a small electronic device composed of three parts: a generator, one or more leads, and an electrode on each lead. A pacemaker signals the heart to beat when the heartbeat is too slow.

Illustration of a single-chamber pacemaker
Click Image to Enlarge

A generator is the “brain” of the pacemaker device. It is a small metal case that contains electronic circuitry and a battery. The lead (or leads) is an insulated wire that is connected to the generator on one end, with the other end placed inside one of the heart’s chambers.

The electrode on the end of the lead touches the heart wall. In most pacemakers, the lead senses the heart’s electrical activity. This information is relayed to the generator by the lead.

If the heart’s rate is slower than the programmed limit, an electrical impulse is sent through the lead to the electrode and the pacemaker’s electrical impulse causes the heart to beat at a faster rate.

When the heart is beating at a rate faster than the programmed limit, the pacemaker will monitor the heart rate, but will not pace. No electrical impulses will be sent to the heart unless the heart’s natural rate falls below the pacemaker’s low limit.

Pacemaker leads may be positioned in the atrium or ventricle or both, depending on the condition requiring the pacemaker to be inserted. An atrial dysrhythmia/arrhythmia (an abnormal heart rhythm caused by a dysfunction of the sinus node or the development of another atrial pacemaker within the heart tissue that takes over the function of the sinus node) may be treated with an atrial pacemaker.

Illustration of a dual-chamber pacemaker
Click Image to Enlarge

A ventricular dysrhythmia/arrhythmia (an abnormal heart rhythm caused by a dysfunction of the sinus node, an interruption in the conduction pathways, or the development of another pacemaker within the heart tissue that takes over the function of the sinus node) may be treated with a ventricular pacemaker whose lead wire is located in the ventricle.

It is possible to have both atrial and ventricular dysrhythmias, and there are pacemakers that have lead wires positioned in both the atrium and the ventricle. There may be one lead wire for each chamber, or one lead wire may be capable of sensing and pacing both chambers.

A new type of pacemaker, called a biventricular pacemaker, is currently used in the treatment of congestive heart failure. Sometimes in heart failure, the two ventricles (lower heart chambers) do not pump together in a normal manner. When this happens, less blood is pumped by the heart.

A biventricular pacemaker paces both ventricles at the same time, increasing the amount of blood pumped by the heart. This type of treatment is called cardiac resynchronization therapy.

Implantable cardioverter defibrillator (ICD)

An implantable cardioverter defibrillator (ICD) looks very similar to a pacemaker, except that it is slightly larger. It has a generator, one or more leads, and an electrode for each lead. These components work very much like a pacemaker. However, the ICD is designed to deliver an electrical shock to the heart when the heart rate becomes dangerously fast, or “fibrillates.”

An ICD senses when the heart is beating too fast and delivers an electrical shock to convert the fast rhythm to a normal rhythm. Some devices combine a pacemaker and ICD in one unit for persons who need both functions.

The ICD has another type of treatment for certain fast rhythms called anti-tachycardia pacing (ATP). When ATP is used, a fast pacing impulse is sent to correct the rhythm. After the shock is delivered, a “back-up” pacing mode is used if needed for a short while.

The procedure for inserting a pacemaker or an ICD is the same. The procedure generally is performed in an electrophysiology (EP) lab or a cardiac catheterization lab.

Other related procedures that may be used to assess the heart include resting and exercise electrocardiogram (ECG), Holter monitor, signal-averaged ECG, cardiac catheterization, chest x-ray, computed tomography (CT scan) of the chest, echocardiography, electrophysiology studies, magnetic resonance imaging (MRI) of the heart, myocardial perfusion scans, radionuclide angiography, and ultrafast CT scan.

The heart’s electrical conduction system
Illustration of the anatomy of the heart, view of the electrical system
Click Image to Enlarge

The heart is, in the simplest terms, a pump made up of muscle tissue. Like all pumps, the heart requires a source of energy in order to function. The heart’s pumping energy comes from an indwelling electrical conduction system.

An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node), which is a small mass of specialized tissue located in the right atrium (right upper chamber) of the heart.

The sinus node generates an electrical stimulus regularly at 60 to 100 times per minute under normal conditions. This electrical stimulus travels down through the conduction pathways (similar to the way electricity flows through power lines from the power plant to your house) and causes the heart’s chambers to contract and pump out blood.

The right and left atria (the two upper chambers of the heart) are stimulated first and contract a short period of time before the right and left ventricles (the two lower chambers of the heart).

The electrical impulse travels from the sinus node to the atrioventricular (AV) node, where it stops for a very short period, then continues down the conduction pathways via the “bundle of His” into the ventricles. The bundle of His divides into right and left pathways to provide electrical stimulation to both ventricles.

What is an ECG?

This electrical activity of the heart is measured by an electrocardiogram (ECG or EKG). By placing electrodes at specific locations on the body (chest, arms, and legs), a tracing of the electrical activity can be obtained. Changes in an ECG from the normal tracing can indicate one or more of several heart-related conditions.

Dysrhythmias/arrhythmias (abnormal heart rhythms) are diagnosed by methods such as EKG, Holter monitoring, signal-average EKG, or electrophysiological studies. These symptoms may be treated with medication or procedures such as a cardiac ablation (removal of a location in the heart that is causing a dysrhythmia by freezing or radiofrequency).

Reasons for the Procedure

A pacemaker may be inserted in order to provide stimulation for a faster heart rate when the heart is beating too slowly, and when other treatment methods, such as medication, have not improved the heart rate.

An ICD may be inserted in order to provide fast pacing (ATP), cardioversion (small shock), or defibrillation (larger shock) when the heart beats too fast.

Problems with the heart rhythm may cause difficulties because the heart is unable to pump an adequate amount of blood to the body. If the heart rate is too slow, the blood is pumped too slowly.

If the heart rate is too fast or too irregular, the heart chambers are unable to fill up with enough blood to pump out with each beat. When the body does not receive enough blood, symptoms such as fatigue, dizziness, fainting, and/or chest pain may occur.

Some examples of rhythm problems for which a pacemaker or ICD might be inserted include:

* atrial fibrillation - occurs when the atria beat irregularly and too fast
* ventricular fibrillation - occurs when the ventricles beat irregularly and too fast
* bradycardia - occurs when the heart beats too slow
* tachycardia - occurs when the heart beats too fast
* heart block - occurs when the electrical signal is delayed after leaving the SA node; there are several types of heart blocks, and each one has a distinctive ECG tracing

There may be other reasons for your physician to recommend a pacemaker or ICD insertion.

Risks of the Procedure

Possible risks of pacemaker or ICD insertion include, but are not limited to, the following:

* bleeding from the incision or catheter insertion site
* damage to the vessel at the catheter insertion site
* infection of the incision or catheter site
* pneumothorax - air becomes trapped in the pleural space causing the lung to collapse

If you are pregnant or suspect that you may be pregnant, you should notify your physician. If you are lactating, or breastfeeding, you should notify your physician.

Patients who are allergic to or sensitive to medications or latex should notify their physician.

For some patients, having to lie still on the procedure table for the length of the procedure may cause some discomfort or pain.

There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.

Before the Procedure

* Your physician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
* You will be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if something is not clear.
* You will need to fast for a certain period of time prior to the procedure. Your physician will notify you how long to fast, usually overnight.
* If you are pregnant or suspect that you are pregnant, you should notify your physician.
* Notify your physician if you are sensitive to or are allergic to any medications, iodine, latex, tape, or anesthetic agents (local and general).
* Notify your physician of all medications (prescription and over-the-counter) and herbal supplements that you are taking.
* Notify your physician if you have heart valve disease, as you may need to receive an antibiotic prior to the procedure.
* Notify your physician if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop some of these medications prior to the procedure.
* Your physician may request a blood test prior to the procedure to determine how long it takes your blood to clot. Other blood tests may be done as well.
* You may receive a sedative prior to the procedure to help you relax. If a sedative is given, you will need someone to drive you home afterwards.
* The upper chest may be shaved or clipped prior to the procedure.
* Based upon your medical condition, your physician may request other specific preparation.

During the Procedure
Picture of a chest X-ray, showing a single-chamber implanted pacemaker
Chest X-ray with Implanted Pacemaker

A pacemaker or implanted cardioverter defibrillator may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician’s practices.

Generally, a pacemaker or ICD insertion follows this process:

1. You will be asked to remove any jewelry or other objects that may interfere with the procedure.
2. You will be asked to remove your clothing and will be given a gown to wear.
3. You will be asked to empty your bladder prior to the procedure.
4. An intravenous (IV) line will be started in your hand or arm prior to the procedure for injection of medication and to administer IV fluids, if needed.
5. You will be placed in a supine (on your back) position on the procedure table.
6. You will be connected to an electrocardiogram (ECG or EKG) monitor that records the electrical activity of the heart and monitors the heart during the procedure using small, adhesive electrodes. Your vital signs (heart rate, blood pressure, breathing rate, and oxygenation level) will be monitored during the procedure.
7. Large electrode pads will be placed on the front and back of the chest.
8. You will receive a sedative medication in your IV before the procedure to help you relax. However, you will likely remain awake during the procedure.
9. The pacemaker or ICD insertion site will be cleansed with antiseptic soap.
10. Sterile towels and a sheet will be placed around this area.
11. A local anesthetic will be injected into the skin at the insertion site.
12. Once the anesthetic has taken effect, the physician will make a small incision at the insertion site.
13. A sheath, or introducer, is inserted into a blood vessel, usually under the collarbone. The sheath is a plastic tube through which the pacer/ICD lead wire will be inserted into the blood vessel and advanced into the heart.
14. It will be very important for you to remain still during the procedure so that the catheter placement will not be disturbed and to prevent damage to the insertion site.
15. The lead wire will be inserted through the introducer into the blood vessel. The physician will advance the lead wire through the blood vessel into the heart.
16. Once the lead wire is inside the heart, it will be tested to verify proper location and that it works. There may be one, two, or three lead wires inserted, depending on the type of device your physician has chosen for your condition. Fluoroscopy, (a special type of x-ray that will be displayed on a TV monitor), may be used to assist in testing the location of the leads.
17. Once the lead wire has been tested, an incision will be made close to the location of the catheter insertion (just under the collarbone). You will receive local anesthetic medication before the incision is made.
18. The pacemaker/ICD generator will be slipped under the skin through the incision after the lead wire is attached to the generator. Generally, the generator will be placed on the non-dominant side. (If you are right-handed, the device will be placed in your upper left chest. If you are left-handed, the device will be placed in your upper right chest).
19. The ECG will be observed to ensure that the pacer is working correctly.
20. The skin incision will be closed with sutures, adhesive strips, or a special glue.
21. A sterile bandage/dressing will be applied.

After the Procedure

In the hospital

After the procedure, you may be taken to the recovery room for observation or returned to your hospital room. A nurse will monitor your vital signs for a specified period of time.

You should immediately inform your nurse if you feel any chest pain or tightness, or any other pain at the incision site.

After the specified period of bed rest has been completed, you may get out of bed. The nurse will assist you the first time you get up, and will check your blood pressure while you are lying in bed, sitting, and standing. You should move slowly when getting up from the bed to avoid any dizziness from the period of bedrest.

You will be able to eat or drink once you are completely awake.

The insertion site may be sore or painful, but pain medication may be administered if needed.

Your physician will visit with you in your room while you are recovering. The physician will give you specific instructions and answer any questions you may have.

Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your hospital room or discharged home.

If the procedure is performed on an outpatient basis, you may be allowed to leave after you have completed the recovery process. However, if there are concerns or problems with your ECG, you may stay in the hospital for an additional day (or longer) for monitoring of the ECG.

You should arrange to have someone drive you home from the hospital following your procedure.

At home

You should be able to return to your daily routine within a few days. Your physician will tell you if you will need to take more time in returning to your normal activities. In addition, you should not do any lifting or pulling on anything for a few weeks. You may be instructed not to lift your arms above your head for a period of time.

You will most likely be able to resume your usual diet, unless your physician instructs you differently.

It will be important to keep the insertion site clean and dry. Your physician will give you specific bathing instructions.

Your physician will give you specific instructions about driving. If you had an ICD, you will not be able to drive until your physician gives you approval. Your physician will explain these limitations to you, if they are applicable to your situation.

You will be given specific instructions about what to do if your ICD discharges a shock. For example, you may be instructed to dial 911 or go to the nearest emergency room in the event of a shock from the ICD.

Ask your physician when you will be able to return to work. The nature of your occupation, your overall health status, and your progress will determine how soon you may return to work.

Notify your physician to report any of the following:

* fever and/or chills
* increased pain, redness, swelling, or bleeding or other drainage from the insertion site
* chest pain/pressure, nausea and/or vomiting, profuse sweating, dizziness and/or fainting
* palpitations

Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.

Pacemaker/ICD precautions

The following precautions should always be considered. Discuss the following in detail with your physician, or call the company that made your device:

* Always carry an ID card that states you are wearing a pacemaker or an ICD. In addition, you should wear a medical identification bracelet that states you have a pacemaker or ICD.
* Use caution when going through airport security detectors. Check with your physician about the safety of going through such detectors with your type of pacemaker. In particular, you may need to avoid being screened by hand-held detector devices, as these devices may affect your pacemaker.
* You may not have a magnetic resonance imaging (MRI) procedure. You should also avoid large magnetic fields.
* Abstain from diathermy (the use of heat in physical therapy to treat muscles).
* Turn off large motors, such as cars or boats, when working on them (they may temporarily “confuse” your device).
* Avoid certain high-voltage or radar machinery, such as radio or television transmitters, electric arc welders, high-tension wires, radar installations, or smelting furnaces.
* If you are having a surgical procedure performed by a surgeon or dentist, tell your surgeon or dentist that you have a pacemaker or ICD, so that electrocautery will not be used to control bleeding (the electrocautery device can change the pacemaker settings).
* You may have to take antibiotic medication before any medically invasive procedure to prevent infections that may affect the pacemaker.
* Always consult your physician if you have any questions concerning the use of certain equipment near your pacemaker.
* When involved in a physical, recreational, or sporting activity, you should avoid receiving a blow to the skin over the pacemaker or ICD. A blow to the chest near the pacemaker or ICD can affect its functioning. If you do receive a blow to that area, see your physician.
* Always consult your physician when you feel ill after an activity, or when you have questions about beginning a new activity.

Cardiac resynchronization therapy (CRT) has been shown in several clinical trials to improve symptoms and exercise capacity in patients with advanced heart failure. The first clinical trials of CRT-D devices were based on populations who already met a standard indication for implantable cardioverter defibrillator (ICD) therapy. In these patients, when CRT is contemplated, a CRT-D device is used. In a broad population of patients with advanced heart failure, the choice of adding ICD therapy is less clear.

Methods and results Results of several clinical trials of CRT and ICD use in heart failure are reviewed. An analysis of data suggests that CRT may reduce death due to progressive heart failure. Recently, the COMPANION trial has reported that CRT can reduce long-term morbidity and mortality. CRT can be delivered as a pacemaker only, or in combination with an ICD. Taken alone, an ICD can improve survival in select groups of patients with left ventricular dysfunction; however, adverse effects have been seen, such as worsening heart failure.

Conclusion There are no clinical trials designed specifically to address the relative merits of CRT delivered by pacemaker versus ICD. Based on our knowledge of the effects of both, along with data from recent clinical trials, it appears as though the preponderance of evidence is in favor of CRT-D. More will be learned from clinical trials currently underway

Key Words: Heart failure • Implantable cardioverter defibrillator • Cardiac resynchronization therapy

Introduction

Heart failure is a common disease in developed countries. It is the most common reason for hospitalization among those over the age of 65 years, and both the incidence and prevalence of heart failure are anticipated to increase as the population ages.1,2 Symptoms of heart failure can become disabling, affecting simple activities of daily living. Despite advances in the treatment of heart failure, many patients remain very symptomatic, and both morbidity and mortality remain high, creating a need for improved therapies.

Cardiac resynchronization therapy (CRT) is a recent addition to therapy for symptomatic heart failure.3 CRT has consistently been shown to improve symptoms and exercise capacity in several randomized clinical trials.4–8 Recently, the Comparison of Medical Therapy, Pacing and Defibrillation (COMPANION) trial has demonstrated a substantial reduction in the combined endpoint of mortality and all-cause hospitalization, thereby expanding the importance of CRT in the treatment of heart failure.9

Implantable cardioverter defibrillators (ICDs) have been shown to reduce mortality in patients at high risk for arrhythmia.10–12 Initially, attention was focused on patients with markers for ventricular arrhythmia, such as nonsustained ventricular tachycardia or inducible sustained ventricular tachycardia during an electrophysiology study.10,12 More recently, attention has been drawn to left ventricular systolic dysfunction as a sole risk factor for arrhythmic death.11

CRT is delivered with devices that are either pacemakers alone, or are combined with ICD therapy (CRT-D). The first clinical trials of CRT-D devices were based on populations who already met a standard indication for ICD therapy. Clearly, in such patients, when CRT is contemplated, a CRT-D device is used. In a broad population of patients with advanced heart failure, the choice of device is less clear. Should we implant CRT devices alone, or add ICD therapy?

In this review, the risks and benefits of CRT devices and ICD therapy alone in heart failure patients will be summarized. The risks of CRT-D devices will be reviewed, along with the benefits observed in randomized clinical trials.

CRT

Conduction system disease is common in patients with advanced heart failure and left ventricular (LV) systolic dysfunction, estimated to occur in 25% of patients with advanced symptoms of heart failure and low ejection fraction.13 Such conduction abnormalities may cause an inefficient left ventricular contraction, uneven LV wall stress, increased myocardial oxygen consumption, and increased mitral regurgitation.14,15 In studies of heart failure patients, conduction system disease is associated with increased symptoms and a poor prognosis. CRT has the potential to normalize these abnormalities, thereby improving patient outcome.

The benefits and risks of CRT

Table 1 displays the results of CRT on symptoms, quality of life and exercise capacity in clinical trials. Although the trials used different devices and differed somewhat in methodology, CRT consistently demonstrated a benefit in all these parameters.4–8 Furthermore, the magnitude of benefit is large. In studies of pharmacologic treatment of heart failure, drug therapy known to have long-term benefits is often associated with less improvement or no measurable improvement in some of these metrics.16–18

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Table 1 Effects of CRT on symptoms and exercise capacity in clinical trials

The long-term effect of CRT on morbidity and mortality was not elucidated by these studies. In the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial, the investigators reported that CRT reduced the composite secondary endpoint of death or heart failure hospitalization (8% CRT, 15% control, ).4 Although the findings were very reassuring, the composite endpoint was fairly narrow and the follow-up was limited, leaving doubt about the long-term effects of CRT. In order to provide more insight into the effects of CRT on mortality, Bradley et al.19 performed a meta-analysis of survival using data from the four of the trials listed in Table 1. Although they were unable to demonstrate an overall mortality benefit (RR 0.77, 95% CI 0.51–1.18), the trend was reassuring and a reduction in death due to progressive heart failure became apparent (RR 0.49, 95% CI 0.25–0.93). The methods used in these trials were to randomize patients after a functioning CRT device was successfully implanted, thus negating any potential adverse effects of the implant in the data analysis.

This series of studies of CRT brought this new therapy to clinical practice by providing consistent evidence of substantial improvement in symptoms, exercise capacity and quality of life. The data on morbidity and mortality were clearly trending in the right direction, but were not certain. The risks of CRT implants appear to be relatively low, but certainly deserve attention. The adverse event rates for the Multisite Stimulation in Cardiomyopathies Trial (MUSTIC), MIRACLE, MIRACLE-ICD and CONTAK CD clinical trials are shown in Table 2.4,6–8 Deaths around the time of implant are uncommon, but do occur. The most common adverse events were related to lead dislodgement, followed by coronary sinus trauma.

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Table 2 Complications of implantation of CRT devices

The risks and benefits of ICD therapy in a heart failure population

As mentioned, the study of prophylactic ICD therapy has evolved from evaluating those with markers for ventricular arrhythmias, to evaluating those with severe LV systolic dysfunction and finally those with symptomatic heart failure.10–12,20

The first trial to demonstrate a benefit of prophylactic ICDs in patients with LV dysfunction was the Multicenter Automatic Defibrillator Implantation Trial (MADIT).10 In this study, patients with a history of myocardial infarction, low LVEF (<40%) and nonsustained ventricular tachycardia were screened. If eligible, they underwent electrophysiology (EP) study to determine whether they were inducible for sustained ventricular tachycardia (VT). They were then tested to determine whether procainamide could suppress the arrhythmia, and only if procainamide failed to suppress VT were they enrolled in the study. Patients were randomized to an ICD or no ICD. Medical therapy was prescribed at the investigators' discretion.

A total of 196 patients were enrolled in the study. Mortality, the primary endpoint, was substantially lower for the ICD group, a 54% relative risk reduction at a median follow-up of 27 months. Two issues confounded the study. First, there was only a modest use of drugs known to be beneficial for patients with LV dysfunction, with 50–60% of the cohort being treated with an ACE inhibitor. Furthermore, there was a disparity in the use of ß-blockers, with 31% of patients in the ICD receiving the beneficial effects of ß-blockers compared with only 14% in the control arm at last contact. Although the magnitude of benefit was impressive, the overall small numbers and disparity in medical therapy between the groups left the community of physicians treating heart failure somewhat skeptical.

The Multicenter Unsustained Tachycardia Trial (MUSTT) study was a trial to study the approach of electrophysiologically guided therapy versus no antiarrhythmic therapy for a population at high risk for mortality from sudden death.12 Patients included had a history of a myocardial infarction, a low ejection fraction (<40%) and documentation of nonsustained VT. For the EP guided therapy group, the protocol stipulated a series of therapeutic trials, with the possibility of an ICD as an option if drugs failed to suppress the VT. As the trial progressed and more experience was gained with nonthoracotomy ICD implants, the ICD was used more frequently. The results demonstrated a modest benefit of EP guided therapy for the primary endpoint of cardiac arrest or death from arrhythmia. When the EP guided therapy group was divided into those treated with ICDs and those treated with antiarrhythmic drug therapy, it became apparent that all of the benefit rested with the patients treated with an ICD. If one evaluates those who happened to have received an ICD compared with those in the control group, the result was a 60% reduction in mortality with the ICD (RR 0.40, 95% CI 0.27–0.59). Unfortunately, the primary hypothesis of the trial did not involve an ICD and the patients who received an ICD were not randomized to that therapy, but were selected by their treating physicians, leaving the potential for bias. Accordingly, the results of the trial were left open to other interpretations.

As a result of impressive apparent benefits of prophylactic ICD therapy, the authors of the ACC/AHA guidelines for pacemaker and ICD implant endorsed the use of the prophylactic ICD for patients who would meet either the MADIT or MUSTT criteria.1,2 The authors of the ACC/AHA heart failure guidelines, while acknowledging these studies and recommending physician discretion in the use of these indications, did not strongly endorse these methods and actually recommended against screening for asymptomatic arrhythmia that would identify patients would meet the MADIT or MUSTT criteria. The authors of the ESC guidelines for the treatment of chronic heart failure reviewed some of the above studies, but noted that a broad heart failure population has not been studied.

The MADIT II study represented a departure from prior studies for patient selection. Instead of using markers of arrhythmia for entry, such as nonsustained ventricular tachycardia or the results of EP studies, the major risk criteria were a history of myocardial infarction and a very low ejection fraction (<=30%).11 In this respect, the MADIT II study becomes a study of left ventricular systolic dysfunction, rather than ventricular arrhythmia. This study was a prospective, randomized, controlled clinical trial that was not confounded by imbalances in medical therapy or issues with treatment assignment. The study demonstrated an impressive 31% reduction in all-cause mortality at a median follow-up of 20 months. Two issues raised concerns. First, it took more than one year to begin to see a mortality benefit with the ICD. Second, there was an increase in heart failure hospitalization in the ICD group, with an absolute difference of 5.0% (similar to the mortality benefit of 5.6%), and a rate of 9.4 vs. 11.3 hospitalizations per patient month () for the control and ICD arms, respectively. The study may have been confounded by right ventricular pacing which appears to have the potential for causing worsening heart failure.21,22 In the MADIT II study, neither the choice of specific device, nor the pacing mode were mandated by protocol, but were left to the investigators' discretion.

When taking these studies together, there is a consistent survival benefit seen with ICDs in patients with LV dysfunction. Concern has been raised about the possibility of adverse effects of ICDs causing unforeseen problems such as worsening heart failure, and there is no proposed mechanism or clinical observation that suggest that ICDs can improve the heart failure condition.

Finally, the Sudden Cardiac Death Heart Failure Trial (SCD-HeFT) was recently reported.24 This, trial was designed to assess the potential of either an ICD or amiodarone to reduce the risk of sudden death in a broad population of heart failure patients (NYHA Class II and III) with low ejection fraction. The trial demonstrated no effect with amiodarone, but a 23% reduction in the risk of all-cause mortality with an ICD (HR 0.77, 97.5% CI 0.62–0.96, ). This was the first clear demonstration of a benefit of ICD therapy in a broad heart failure population, and will clearly increase the use of ICDs in this group. However, there was a difference in the benefit seen in Class II and Class III heart failure. Patients with Class II heart failure had a dramatic benefit (HR 0.54, 97.5% CI 0.40–0.74), whereas those with Class III heart failure had no clear benefit (HR 1.16, 97.5% CI 0.84–1.61). Caution should be used in interpretation of this subgroup finding and more information will be forthcoming regarding potential reasons for this observation. This finding, in combination with the finding of worsening heart failure in