Medical Mystery: The ordeal of a constantly halted heart

Half of cardiac arrest patients don't make it to the hospital alive. But a local man had a guardian angel looking out for him the day that he collapsed on the sidewalk while running errands - a nurse happened to be passing by and started CPR.

He was rushed to a nearby hospital, where he suffered multiple seizures. Then, he was transferred to Jefferson Hospital for Neurosciences under the assumption that he collapsed due to seizures. But an assessment there found his seizures were likely due to lack of oxygen in the brain caused by the cardiac arrest. My colleagues transferred him to the cardiac-care unit at Thomas Jefferson University Hospital for a full workup.

While the team was conducting lab tests and cardiac screenings, the patient continued to go into ventricular fibrillation, initiating a "code" - those high-stress responses you see on TV when someone yells, "clear!" before shocking the patient's heart back into rhythm. Ventricular fibrillation, or V-fib, is an electrical disturbance in the heart that causes it to quiver, unable to beat - a cardiac arrest. During the next few days, the patient went into V-fib and cardiac arrest more than 25 times.

Risk factors for ventricular fibrillation for people over age 50 are related to coronary artery disease, including high cholesterol, lipids, and lifestyle. But for patients under 50, the risk factors are heart muscle disease or a congenital electrical abnormality.

My patient was only 44, with no record of heart trouble in his family or his own medical history. He was a healthy nonsmoker. His cardiac catheterization showed no coronary disease, which can sometimes set off a cardiac arrest.

So, what was causing the repeated cardiac arrests in this otherwise healthy patient?

The first clue came from the patient's first electrocardiogram (EKG). It showed frequent premature beats that seemed to be initiating the ventricular fibrillation. The premature beats all looked the same, suggesting that they were arising from the same place in the heart.

We started medication to treat this condition, but the patient continued to have recurrent V-fib and cardiac arrest. Our next step was to locate the origin of the premature beats and eliminate it.

Using the EKG, we can localize the source of the electrical activity in the heart. This patient's EKG suggested that the premature beats triggering V-fib were originating in his right ventricle and potentially in his moderator band. The moderator band is a muscular structure in the right ventricle that connects the septum to the anterior papillary muscle. The papillary muscle is part of the supporting structure of the tricuspid valve, which is the heart valve between the right atrium and right ventricle. It is thought that the moderator band facilitates the flow of electrical impulses from the conduction system in the septum to the papillary muscle.

The literature has pointed to the moderator band as a potential source of V-fib. I've encountered only a handful of such cases in 36 years of practice.

My colleagues, Drs. Reginald Ho and Daniel Frisch, then took the patient to the electrophysiology lab. In order to determine the precise location of the premature beats we needed to place catheters into the heart and create a three-dimensional map. Once the catheter was placed at the target site, radio-frequency energy was delivered to the trigger site - which, as we suspected, was along the moderator band in the right ventricle.

You can see why we call this process "map it and zap it."

Along the way, our patient endured dozens of episodes of cardiac arrest, requiring everyone on our phenomenal team to work on keeping him going until our electrophysiology cardiologists could eliminate the source of the trouble.

The patient had no future episodes of V-fib. But to be safe, we implanted a defibrillator, which will shock his heart back into rhythm if he should experience another episode outside of the hospital.

Along with medication and close observation, we expect our patient to live a long, healthy life, due to the quick action of a nurse who happened to be passing by, and our multidisciplinary team here at Jefferson.

Arnold J. Greenspon, M.D., is director of the Cardiac Electrophysiology Laboratory at Thomas Jefferson University Hospital, and professor at Sidney Kimmel Medical College at TJU.