Mending Broken Heartbeats
By Steven Higgins, M.D., Scripps Memorial Hospital La Jolla
Have you ever felt your heart “race” when you are excited or anxious? Or measured your heart rate after exercising?
The speed and pattern of our heartbeats can tell us a great deal about our cardiac health. A faster heart rate when you’re climbing a flight of stairs is probably normal; a heartbeat that speeds up or “skips” beats for no apparent reason may be a sign of a serious heart problem. That’s where cardiac electrophysiology comes in—and it can often save a life.
What is Cardiac Electrophysiology?
Cardiac electrophysiology, commonly knows as EP, is the study of the heart’s electrical system. EP procedures, or catheter studies, are performed for several reasons. One is to diagnose abnormalities in the heart’s rhythm, called arrhythmia, when the heart beats too slowly, too quickly, or in an unusual pattern. In some patients, arrhythmia can cause fainting or even sudden death, which is why it is important that we evaluate it with an EP study. We also perform EP studies to treat and correct cardiac abnormalities.
Today, the most common reason to perform an EP study is to perform a curative procedure called an ablation. In an ablation, after the arrhythmia is diagnosed and mapped, an area of the heart can be altered with heat to permanently prevent the heart irregularity from recurring. For many arrhythmias, an ablation has a greater than 95% of permanently eliminating the problem.
EP: A Standard of Care
Not too long ago, cardiac EP was a small, highly specialized field. These days, however, it has grown into a major area of cardiac care. A number of EP procedures that once were reserved for very specialized cases have now become standard. For example, implantable cardiac defibrillators (ICD) that regulate heartbeat by delivering electrical shocks to the heart were once used only in patients who had experienced at least two life-threatening cardiac arrests (heart stoppages). However, recent clinical trials that Scripps doctors participated in found that an ICD could dramatically lower that risk in selected patients. Now, ICDs are a mainstay of cardiac therapy most commonly inserted even before the first arrhythmia occurs to prevent it from ever developing.
Another example is cardiac resynchronization therapy or CRT, which re-synchronizes the actions of the left and right ventricles in patients with heart failure, which is the number one reason for hospital admission. About 10 years ago, the Scripps La Jolla Regional Cardiac Arrhythmia Center was at the forefront of developing CRT, also called biventricular pacing, and we were the second in the United States to perform this therapy. Now it, too, has become standard therapy for selected patients with heart failure.
New Therapies, New Hope
Moreover, new advances in EP offer even more options for patients with heart problems.
Pulmonary vein isolation, or PVI, is one of the newest treatments we offer at Scripps. This type of ablation is for patients with atrial fibrillation, an abnormal heart rhythm that occurs either intermittently or steadily. Atrial fibrillation is the most common arrhythmia as well as the most common cause of strokes; it occurs when a band of muscle cells surrounding the opening of the pulmonary veins sends out an electrical charge which may trigger the heart to beat rapidly and irregularly. In the past, atrial fibrillation was treatable only with medications, and often they were not effective or caused serious side effects. PVI destroys the band of muscle cells by applying heat energy through a catheter and, often cures atrial fibrillation.
In the coming months, we expect to be treating arrhythmia using an innovative new tool called the Stereotaxis Magnetic Navigation System. In order for arrhythmia treatment to be successful, we must be able to position the catheter precisely where it needs to go, often in areas of the heart that are difficult to reach, especially with conventional rigid catheters. Stereotaxis uses a very soft, flexible catheter (think of a piece of cooked spaghetti) with a metal tip at one end; giant magnets outside the patient’s body safely steer the catheter through the veins with robotic control. This computerized, magnetic navigation system will enable us to target the areas of the heart that need treatment.
Scripps is currently raising funds to acquire a Stereotaxis unit as part of a five million dollar fundraising drive to renovate and expand the Regional Cardiac Arrhythmia Center; Scripps hopes to begin construction on the Stereotaxis unit this summer.
Steven Higgins, M.D., is Director of Electrophysiology at Scripps La Jolla Regional Cardiac Arrhythmia Center. For more information, please call 1-800-SCRIPPS