The implantation in Charles Brining, 58, a Hagerstown machine operator, was conducted Oct. 7 by cardiologists Stephen Shorofsky, M.D., Ph.D, and Michael R. Gold, M.D., Ph.D., director of the electrophysiology lab at the University of Maryland Medical Center.
Only 27 of these implants have been done so far, and this was the first in the mid-Atlantic region including Maryland, Delaware, Pennsylvania and the District of Columbia. The procedure was part of a Phase I study approved by the Food and Drug Administration to investigate the safety and efficacy of the device.
The device, made by InControl, Inc., of Redmond, WA, fits under the skin at the top of the chest, with lead wires attached to the heart through a vein under the collarbone. It is about the size of a deck of cards and delivers a small electrical shock to regulate a dangerously rapid heartbeat.
Until development of the new device, external shocks delivered through patches attached to the skin were performed in a hospital. "This is an implantable device that will do it automatically and internally, with an option for the patient to control its use and receive therapy outside the hospital," Gold says.
Implants of ventricular defibrillating devices have been done for about 10 years in patients with life-threatening arrhythmia in the lower chamber of the heart, called the ventricle. The new device was developed when it became possible to use less energy to defibrillate the heart, making the procedure more comfortable for the patient.
The device, called the Metrix System TM, operates in three different modes: automatic, in which it delivers a warning and then therapy when arrhythmia is detected; monitor mode, in which it is activated by a physician in an office or hospital; and patient-activated, in which the wearer self-administers the shock. The batteries should last four or five years.
Mr. Brining says he has had atrial fibrillation for several years. "At first, I didn't notice it. But after a while longer, I was out of breath and feeling run-down," he says. He was referred by his local physician to the University of Maryland Medical Center after external electric shocks and standard medications were not effective.
Atrial fibrillation is the most common heart rhythm disorder and can cause up to a 30 percent reduction in the pumping output of the heart. Symptoms include shortness of breath, palpitations, lightheadedness, fainting, fatigue and reduced exercise capacity. Medications prevent recurrent episodes in only about half of patients.
Although atrial fibrillation is not immediately life-threatening by itself, those who have it are five times more likely to have a stroke than those with normal heart rhythms, and of those who do, 70 percent die or suffer severe brain damage. The cost to the U.S. healthcare system of atrial fibrillation in 1994 was more than $1.3 billion.