(March 12, 2009 - Insidermedicine) In this video, Dr. Kenneth Ellenbogen, MD, discusses what he would do if he had a racing heartbeat and was diagnosed with supraventricular tachycardia (SVT). Dr. Ellenbogen is Professor of Medicine (Cardiology) and Director of Clinical Cardiac Electrophysiology and Pacing at Virginia Commonwealth University Medical Center.
At the American Heart Association's Scientific Sessions in New Orleans, we spoke with Dr. Kenneth Ellenbogen. Who is a Professor of Medicine and Director Clinical Cardiac Electrophysiology and Pacing at Virginia Commonwealth University Medical Center.
If I had a racing heartbeat and was diagnosed with SVT...
Dr. Ellenbogen: In a person, patient, or anyone who feels they are having episodes of fast heart beating really the first step in that evaluation is to confirm that they in fact have SVT, or Supraventricular Tachycardia. Which is just a term that means any of a number of different types of fast heart beating coming from the top chamber of the heart. We'll go ahead and assume that it is an SVT but it is worth stating that a lot of people will experience a sensation of a fast heartbeat. And there are lots of ways to record an electrocardiogram without having a patient in the doctor’s office or in the emergency room.
The first thing is to try to make some effort to record an EKG. It can be recorded with a transtelephonic monitor. If the episodes are brief in duration, it can be recorded with a continuous loop monitor that a patient wears. Its sort of like an iPod, its very light weight and it can be activated by the fast heart beating, or the patient can activate it. The device has a retrograde memory, storing all the heart beats from 30 seconds to a couple of minutes before they activated it, and a couple minutes afterwards.
But to diagnose the type of fast heart beating as a Supraventricular Tachycardia ideally the best situation would be to see a cardiac electrophysiologist, and we all want the best for our family and friends. A cardiac electrophysiologist is somebody who is board certified in cardiology and has had one or two additional years of training in the management of patients with cardiac arrhythmias.
What does the history and physical examination consist of?
Dr. Ellenbogen: In the doctor's office the beginning evaluation includes a history and a physical. The history portion of the examination will probably include questions like: "How long have you had episodes of fast heart beating? How long do they last? Are there any particular things that provoke them? Drinking a cold beverage, exercising on the treadmill?” and then the frequency of episodes.
Oftentimes patients will say, "When I take a deep breath and blow out, I can stop my episodes." So anything a patient may have learned or noted that tends to stop their episodes. And then of course we want to know what kind of symptoms a patient has during the arrhythmia. Because that will really influence, to some level, the treatment. Do you pass out? Do you feel like you are going to pass out? Or is it just "well I feel my heart beating faster but that is okay, I can still do what I need to do." So that is part of the history.
The other part of the history that is very important would consist of a family history. Because there are some arrhythmia syndromes that can be inherited. Physical examination will consist of a complete physical examination. Of course sometimes there are certain abnormalities that can be picked up on during the physical examination that may be associated with certain types of fast heart beating. A 12 lead electrocardiogram recording of the heartbeat is absolutely critical, essential part of the evaluation. Lab work is often done. In particular testing of the thyroid because patients who have overactive thyroids can sometimes have rapid heart beats.
What diagnostic tests are ordered?
Dr. Ellenbogen: Addition lab work might be necessary based upon certain findings on the patient’s exam. If a patient has lost a tremendous amount of weight, then one might think of a thyroid problem and there can be a tumor on the adrenal gland that can cause that so blood test to look at adrenal hormones would be useful. Although, in general practice, that is rare. Certainly a part of the exam that is done very frequently is a transthoracic ultrasound or echocardiogram. This performed using a transducer, or a machine that delivers sound waves through the chest wall, which allows us to really carefully look at co-existing conditions like hypertrophic cardiomyopathy. And in particular to look for forms of congenital heart disease that may be associated with some forms of rapid heart beating. So an ultrasound exam, which is completely safe, would be the number one non-invasive test that is done to further evaluate patients that have supraventricular tachycardia.
What are the implications of SVT?
Dr. Ellenbogen: SVT can be a very benign disease. And in some cases it can be associated with an increase risk of sudden cardiac death due to ventricular fibrillation. So it really is critical to see the appropriate kind of cardiologist, which is a cardiac electrophysiologist, to be able to really stratify. For example take a patient who is young and has supraventricular tachycardia. And on a 12 lead EKG has evidence of what we call an accessory pathway, which is an abnormal connection between the top and bottom chambers of the heart. This patient could be at risk of having cardiac arrest. As opposed to a patient who has a normal EKG, normal echo, and has rare episodes of tachycardia once every two or three years that are associated with minimal symptoms.
How is SVT managed?
Dr. Ellenbogen: There are many ways to treat supraventricular tachycardia. That’s the good news. The second piece of good news is that the vast majority, 85% to over 90%, of patients who have supraventricular tachycardia can have their disease cured by use of radiofrequency, or cryo freezing through a catheter. It can be the type of disease that is very amenable to curing. That being said in some patients no treatment, if the episodes are very infrequent and minimally symptomatic, may be appropriate. Or treatment with drugs that have been around for multiple decades like beta-blockers or calcium channel blockers may be appropriate therapy. There are some patients that will only need to have therapy when they have an episode. And their therapy can consist of taking a pill or it can consist of doing maneuvers such as bearing down or sticking their hand in a bowl of ice, that termination the fast heart beating. For some patients who cant tolerate taking pills, don’t want to take pills, young patients who want to get pregnant, patients who have severely disabling symptoms from their arrhythmias, or patients who have symptoms from their arrhythmias that can't be controlled by medication -- in those patients its preferable to have an invasive procedure, like a heart catheterization, that has a high chance of destroying the abnormal pathway, and curing the tachycardia.
What are the risks of these procedures?
Dr. Ellenbogen: There are some risks associated with catheter ablation procedures. Those risks are somewhat dependent on where the abnormal pathway is located. So in some patients who have a very common form of tachycardia where the abnormal pathway is near the conduction system there is a 1 in 100, or slightly less than that, maybe 1 in 250, risk of damage to the conduction system. Potentially requiring a permanent pacemaker. In patients who have pathways located on the left side of the heart, there is a very small risk associated with that of stroke. In general in many centers where there are experienced people who are doing catheter ablation for many years, or do many cases, the risk of a life threatening or serious adverse complications can be less than 1 in 500, to less that 1 in 1000. So in general it is an extremely safe procedure. And in many cases is much safer than cardiac catheterization or cardiac angiography.
Dr. Ellenbogen: If I had a racing heartbeat and was diagnosed as having supraventricular tachycardia I would want to go to see a cardiac electrophysiologist. I would have a history and physical examination, an electrocardiogram, and an echocardiogram. Then I would sit down with my doctor and based upon the frequency and severity if my symptoms as well as the results of my electrocardiogram would decide what was the best treatment for me. If my symptoms were severe then I would want to have catheter ablation. If my symptoms were extremely infrequent and extremely mild then I might not have anything done, or take a pill when I have an episode, or try to terminate them. For those people who are in between a lot of what they choose will depend upon their lifestyles, or quality of life, or their risk of having a life threatening problem from their tachycardia if the future.