Dr. Dan M. Roden
VUMC doctors launch family-centered care for arrhythmias
Terry Plunkett is examined by Dr. Dawood Darbar in the genetic arrhythmia clinic. (photo by Dana Johnson)
A new clinic specializing in the assessment and treatment of genetically linked heart arrhythmias has opened at Vanderbilt University Medical Center. Staffed by both adult and pediatric cardiologists, the Genetics Arrhythmia Clinic is the first of its kind in the region to offer such services to parents and children in one setting.
Acting as a consultative service, the clinic sees patients referred by other physicians in the area, including those in Vanderbilt’s own cardiology practice, when it seems likely that a familial genetic component is involved.
“There is an increasing appreciation of the role of genetics in who gets arrhythmias, when they get them, and how serious they are going to be,” said Dr. Dan M. Roden, William Stokes Professor of Experimental Therapeutics and professor of Medicine and Pharmacology. “Yet this is an area where most practitioners are unfamiliar, even some arrhythmia experts.”
Roden and the other cardiologists — Drs. Frank A. Fish, Dawood Darbar, and Prince J. Kannankeril — who staff the clinic have much more than a passing interest in the families they treat. Each has an active research program investigating the genetic basis of arrhythmias. The clinicians hope to learn as much from the patients as the patients do from them.
“This is a win-win scenario, because the kind of patients that we are seeing are real diagnostic and therapeutic challenges to most physicians,” said Roden. “We have something unique to offer in terms of the kinds of clinical experience and research protocols that we offer.”
Most people experience, on occasion, some version of an arrhythmia, or irregular heartbeat, that is harmless. A recurrent arrhythmia, on the other hand, could be more serious, even life-threatening.
Atrial arrhythmias — the more common variety — are generally associated with heart disease, particularly high blood pressure, but may have other causes or no apparent cause. Some 5 million people in this country experience atrial arrhythmia and, said Roden, “if one-half to three-quarters of them have a genetic contributor, it wouldn’t surprise me a bit.”
In ventricular arrhythmias, the heart’s beating becomes so uncoordinated that it is reduced to mere twitching. As a result, no blood is pumped and, if not corrected, death ensues within minutes. Incidences of ventricular fibrillation are rare, triggered usually by a stressor, such as an unexpected noise, physical exertion, or strong emotion. In most cases, said Roden, “99.9 percent of heartbeats are normal all through life.”
One family recently visiting the clinic was referred for just such an occurrence. Fifteen-year-old Shalonda Morton collapsed on the court during a high-school basketball game. Though CPR was administered there and in the ambulance en route to Vanderbilt’s emergency room, the efforts to restart her heart were unsuccessful and she died.
The coroner attributed Shalonda’s death to a colloidal brain cyst, but concerned that the cause might have something to do with her heart, Vanderbilt doctors contacted the family through the girl’s pediatrician.
“They told me that when you are a healthy, athletic person and you drop like that, a high percentage of the time it has something to do with the heart,” said her mother, Yolanda Morton. “They wanted her siblings tested to make sure that they didn’t have the same problem.”
The family was referred to Dr. Prince J. Kannankeril, assistant professor of Pediatrics and one of two pediatric cardiologists at the clinic. After several cardiac function tests, Morton’s 17-year-old son Jerry was relieved to hear he had no detectable problem. “I’m glad that the doctor says the tests today looked good,” he said. “I play sports, so it was reassuring.”
Initial test results for 16-year-old daughter LaToya were not as clear-cut, however. When she returned a few days later to be tested while exercising on a treadmill, Kannankeril was able to identify a subtle irregularity on her electrocardiogram called long QT syndrome, an abnormal rhythm that can throw the heart out of synchrony and cause cardiac arrest.
In long QT syndrome, the electrical system of the heart is unstable, which can lead to ventricular fibrillation. At least five genes and close to 200 variants in those genes have so far been associated with the instability, which may or may not run in families. At Kannankeril’s urging, the entire Morton family is scheduled to come back to the genetics arrhythmia clinic next month for further testing.
“It’s important to allay fears,” said Dr. Dawood Darbar, assistant professor of Medicine. “Our goal is primarily to educate families, to sit down with them to discuss the situation and make a plan. Most seem very glad to have this kind of care.”
Often, just having a diagnosis is a relief. For eight years, 22-year-old Terry Plunkett said, doctors told him that the racing heart, lightheadedness, and interrupted sleep he was experiencing “was all in my head.” While on vacation four months ago, another alarming episode prompted him to seek care at nearby Tennessee Christian Medical Center. A physician there diagnosed an atrial arrhythmia and referred him to Vanderbilt’s clinic.
Now under Darbar’s care, Plunkett is relieved to have his suspicions about his heart validated. “I’m just ready to have something done about it,” he said. It turns out that others in his family — father, cousin, uncle, and grandfather — have also struggled with the same kinds of symptoms. One goal of Darbar’s research is to identify families like Plunkett’s that will help pinpoint the genes that caused his problem.
The clinic has the potential, Roden believes, to develop from a referral service into a clinical research resource to serve the patients and families who have a genetic predisposition to developing arrhythmias.
“We’re here at the end of the genomics revolution and it’s not very clear how genetics is going to affect practice,” he said. “In this clinic we will see people with more pure forms of genetic (heart) diseases. By following large numbers of these patients, we can learn things that we wouldn’t have by seeing them in regular practice.”