Heart: Sudden Cardiac Death

Quiz: Sudden Cardiac Arrest!

The Doctor Is In: What You Should Know About Sudden Cardiac Death

By David Cannom
WebMD Live Events Transcript

Event Date: 7/12/2001

Vice President Dick Cheney walked into the hospital on a Saturday and left the same day with a tiny implant near his left shoulder, programmed to save him from sudden cardiac death (SCD). What is sudden cardiac death? And what is this new device? Could it help you or someone you love? David S. Cannom, MD, FACC, will be in the WebMD Live Auditorium to answer your questions about SCD.

The opinions expressed herein are those of the guest's alone. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.

Moderator: Welcome to WebMD Live. Our guest today is Dr. David Cannom. He'll answer your questions about heart rhythms, sudden cardiac death, and procedures to maintain heart rhythm. You may ask a question at any time.

Moderator: Welcome to WebMD Live, Dr. Cannom.

Cannom: Thank you.

Moderator: Before we begin taking questions, can you please tell everyone a little bit about your background and area of expertise? I think everyone would like to know more about what an electrophysiologist does.

Cannom: I'd be happy to. My background and training is in cardiology at Stanford. Prior to that I had training in arrhythmia at the Staton Island Public Service Hospital. That was in the early days of clinical arrhythmia study and there were only 25 of us that were there over 7 years.  Since then this has grown into a major component of cardiology with some 1,700 cardiologists practicing this specialty. The specialty deals with the study of complex electrical signals from the heart that can have serious health consequences if they are not treated properly, the most serious of which is sudden death. The other part of the specialty is cardiac pacing, which is delivery of electrical impulses to speed the heart up.

Moderator: Can you please discuss the recent procedure that Vice President Cheney underwent?

Cannom: Vice President Cheney underwent the implantation of what we call an implantable cardioveter defibrillator or ICD.  The device that we are talking about is implanted in the heart by a lead system about the size of two long straws that are placed in the heart with the power pack placed under the skin in the left shoulder and about the size of a deck of cards.  The device has now been in clinical use for 15 years and will deliver a shock to the heart if a lethal rhythm develops. It also has pacing backup if the heart rate gets too slow. The major function is to  prevent a premature, unplanned arrhythmic death. These occur frequently in patients who have had prior heart attacks and have lost a substantial amount of ventricular muscle during their heart attack, as was the case with Cheney.

Moderator: Is it normal that someone can have the device implanted and leave the hospital the same day?

Cannom: Good question! The typical practice -- and we implant approximately 300 devices a year at our hospital -- is to keep the patient for at least a day after the implantation.

Moderator: How is the patient monitored following implantation?

Cannom: The patient is monitored on a cardiology ward with an arrhythmia detection system as well as careful attention to the wound over the device.

Moderator: How common is sudden cardiac death?

Cannom: Sudden cardiac death is one of the most important causes of mortality in the U.S. per year. The heart association estimates that approximately 250,000 people die suddenly each year in this country and are dying of a rapid electrical series of impulses. Once this attack begins it takes only some six or seven minutes until death ensues. It is during that time that ICD restores a normal rhythm; in fact,  the restoration of normal rhythm takes about eight to 10 seconds. The leading cause of sudden cardiac death is coronary disease due to fatty deposits, and the first manifestation of heart disease is sudden death in about 50% of the patients who have heart trouble.  The other patients who die suddenly already have known heart disease and have their fatal electrical impulse develop as a by-product of muscle scarring. It was to prevent such an episode that lead the George Washington physicians caring for Cheney to implant the ICD.

Moderator: How large are the devices? How long do they last?

Cannom: The devices that we implant are now about 40 cc and are as large as a deck of cards. They last, depending on how frequently they are used, about 8 years. At that point the battery is changed, which requires an operation. The lead system is used as long as it is functioning properly, which is usually a lifetime.

Moderator: Let's take some member questions.

barbara12589_webmd: Does an ICD keep a person from having a heart attack?

Cannom: A heart attack to a cardiologist means any coronary disease that can cause lack of blood flow to the heart muscle.  It does not necessarily imply that a serious electrical abnormality will be part of the lack of blood flow. So the heart attack is the lack of blood flow, and this sometimes, but not always, results in a serious electrical impulse.  This means that the ICD prevents death only in those patients who have an electrical impulse disturbance and does not prevent the heart attack itself.

barbara12589_webmd: I have an ICD; but my heart constantly has trouble with the electrical system. What causes me to be able to feel everything my heart is doing such as skipping, jumping, missing beats, etc.?

Cannom: The electrical abnormalities are likely due to extra beats that you are having called ventricular premature beats or VPB. This is a common complaint  in patients who have had a serious arrhythmia causing an ICD implant, but it is more of an annoyance than a danger. We commonly treat these extra beats with simple drugs like beta-blockers.

Sudden Cardiac Arrest - Test Your Heart Health IQ

Moderator: Member question: My friend's husband died last year of sudden cardiac death. He did not have any signs of heart disease but had a family member with heart-related problems. Our question is, should his children be checked for this type of condition?

Cannom: This is a very important question and more information would be helpful. There are some unusual conditions that are genetically transmitted to children and can be the cause of sudden death. These conditions have very elaborate names but are very important. They include conditions such as hypertrophic cardiomyopathy and right ventricular dysplasia and long QT syndrome. However, most patients who have a lethal arrhythmia with these conditions die in their 20s and 30s and not in their  40s and 50s, and thus I would suspect that your friend had coronary disease as the cause of the sudden death as we have discussed. Only a post-mortem would describe the condition for us. Coronary disease does have a hereditary component that is chiefly manifest as abnormalities in cholesterol or even diabetes.

mommyme1_webmd: Can children with long QT have an ICD implanted?

Cannom: The answer is yes. However, case selection as always is very important. The patient with long QT would only have an ICD implanted if the patient himself had a cardiac arrest.  In certain situations an ICD will be implanted in a patient after a blackout spell or a family member dies of long QT.  Very careful judgment is necessary in these situations. Genetic analysis is sometimes helpful in making these difficult decisions. As the devices become more user-friendly, the threshhold for ICD implantation in long QT is decreasing dramatically.

darleane_webmd: How is the determination as to whether to use ablation OR to insert an ICD made? If neither, what are the names of any medications other than Cordarone that might be helpful?

Cannom: This is an excellent question and an everyday problem. Ablation is a technique that employs a catheter in the heart and uses a high temperature to actually eliminate or destroy the muscle area that is causing a serious heart rhythm. The fact that we can take the hours necessary to do this procedure, which is done commonly now, means  that the rhythm is well tolerated by the patient and that the pumping function of the heart is relatively normal.  If the rhythm is poorly tolerated or the muscle function of the heart is seriously compromised then we usually favor an ICD. If the pumping function is reduced by over 30% then an ICD is usually recommended.  However, normal hearts with well-tolerated, sustained arrhythmia are excellent ablation candidates. There are literally hundreds of thousands of ablations being done around the world as this  technology matures.

Moderator: Member question: In his statement, Cheney stated that he had no symptoms, but that an arrhythmia was picked up on a 34-hour monitor. Why was this placed? Are we to assume that Cheney would support reimbursement for Holter monitoring on all of our asymptomatic patients with ischemic cardiomyopathies and appropriate EP studies and ICD implants as indicated?

Cannom: I suspect that the questioner's background goes beyond the Time Magazine article. Patients with a compromised muscle function after a heart attack should be routinely screened for potentially malignant heart rhythms as was done with Cheney. The rhythms that we are looking for are short runs of ventricular rhythms, which are commonly found when they are looked for. There is great concern among arrhythmia specialists that this type of screening is not being done frequently, or in a uniform fashion, and as a result patients are not receiving ICD's. This is a matter of physician and public education even though the trials that identified a benefit for ICDs in this situation are now over five years old.  Certainly the Cheney case has galvanized interest among physicians in appropriate screening for potential sudden death victims. The answer is the Holter monitors are reimbursable.

deeppp_webmd: If you have had a heart attack what should you do to find out if you are at risk of dying suddenly?

Cannom: Another excellent question. The components of an adequate post-heart attack screen include a measure of pumping function such as a cardiac echo (you want the pumping function over 40%) and a test, usually a treadmill, to look for any compromised blood flow. Only if either of these tests are abnormal would further testing be necessary. It goes without saying that a contemporary medical therapy would include beta-blockers, aspirin, and statins.

bluewillow_webmd: Should a person suffer sudden cardiac arrest while they have an implant device, what type of warning signs or reactions do they suffer?

Cannom: The time table is a very short one. It takes only four seconds or so for the ICD to detect a rapid rhythm and another four seconds or so for the ICD to charge its batteries and deliver a life-saving shock.  So in that short period of time the patient will either be asymptomatic (without symptoms), develop lightheadedness, or pass out; it depends on the status of the pumping chambers of the heart. However, even with an ICD some patients can fall to the ground when their rhythms develop although they will not die.

wilbryant_webmd: Once a CHF device is approved, will today's ICD (right side pacing) become obsolete?

Cannom: Another advanced question. Let me briefly explain why an ICD will not become obsolete but will be part of a integrated treatment system when CHF pacing is widely employed. As a matter of fact, the first congestive heart failure pacing device received preliminary FDA approval two days ago.  The new pacing devices are designed to make heart muscle contraction more coordinated and employ a pacing lead in both the right and left pumping chamber in order to assure coordinated contraction.  It is the discoordinated cardiac contraction that causes heart failure in some 20% to 25% of heart failure patients. Even after the pumping function is coordinated with right and left heart pacing, there is still a substantial risk of sudden death due to arrhythmia. Probably on the order of 10% per year. Thus the companion ICD is necessary to  prevent arrhythmias at the same time the two-chamber pacing system improves cardiac function. The implementation of this combined therapy will be one of the major undertakings in our field of the next five years as there are some 300,000 U.S. patients presenting with a similar condition each year.

darleane_webmd: After I have either ablation or an ICD, will I be able to resume "normal" activities: walking a distance, up hills, up stairs, not being breathless anymore, etc.?

Cannom: The answer is yes in most cases. An ICD does not limit activity, and the only impediment to activity is the depressed pumping function. Most ablation patients post-procedure are fully active.

deeppp_webmd: Great editorial by you in the L.A. Times. Are there really so many people who are not allowed access to this therapy?

Cannom: The editorial that I wrote made really two points. The first is that the treatment that Cheney received with his ICD was fully appropriate and represented a very reasonable application of the data from well-done clinical trials.  So this was an example of modern American medicine at its best. The second point considered the remarkable ease of application of the therapy. In the real world in which I live there is frequently a great deal of education of the insurers, especially the HMO plans, before a Cheney-like therapy can be applied. Finally, and not in the editorial, most of us believe that only a small percentage of the patients who should receive ICD's (based on the best data from clinical trials) are not receiving the appropriate therapy. One study has estimated that even among survivors of cardiac arrest only 25% to 30% of patients in the U.S. are receiving ICDs. This means  that further physician and patient education is necessary.  Regarding the population of patients, which is large, for patients at high risk who have not yet had a cardiac arrest (such as Cheney) the use of ICDs appropriately is even less. So my point would be that what's good for Cheney is good for the general population if an ICD is needed. Education will be the method by which this happens.

Sudden Cardiac Arrest - Test Your Heart Health IQ

deeppp_webmd: What is it that you do as a heart rhythm specialist that is different from a regular heart doctor?

Cannom: Our specialty has become extremely complex and most cardiologists do not want to make the decisions that heart rhythm specialists make on a daily basis, nor do they perform the procedures, such as ablation, that we spend our days doing. As a result, the majority of referrals that come to arrhythmia centers are from cardiologists rather than primary care physicians. A healthier situation would evolve a better balance between primary care physicians and cardiologists in terms of referrals, and this again is our job in terms of educating primary care physicians. This subspecialty has, much to my surprise, become one of the most important and widely practiced areas in clinical cardiology -- all within the last 10 years.

deeppp_webmd: How does someone find a heart rhythm specialist?

Cannom: The parent organization for arrhythmia specialists is the North American Society of Pacing and Electrophysiology. Their headquarters are in Boston and their web site is www.NASPE.org . Their phone number is (508) 647-0100. The have a very complete listing of their membership by geography and will direct anyone interested to the specialist in their region.

epflip_webmd: As a NASPE member I just wanted to thank you for your countless hours of service to the profession.

Cannom: Very nice. Thank you.

Moderator: We are just about out of time. Dr. Cannom:, before we say goodbye, do you have any closing comments?

Cannom: I have enjoyed the hour. And I am delighted to see the level of interest in the problems that we deal with every day. With so many potential sources of information available, I want to compliment WebMD in providing credible information. This would also hold true for the web sites of NASPE, the AHA, and the ACC. Many thanks for the hour.

Moderator: Unfortunately, we are out of time. Thank you very much for joining us today, Dr. Cannom. It's been a pleasure having you on WebMD Live. Thank you for sharing your knowledge and expertise with us. Members, for more information you can visit the North American Society of Pacing and Electrophysiology (NASPE) web site at www.naspe.org   or visit the WebMD member chat boards devoted to heart conditions and the WebMD Heart Condition Center. Thanks, everyone, and have a great day.

The opinions expressed herein are those of the guest's alone. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.



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Reviewed on 10/23/2003 1:22:08 AM

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