Implantable defibrillator saves life of 57-year old man

on February 12, 2009 at 12:03 AM, updated February 12, 2009 at 12:21 AM
Steve Barnhart, who lives in Gun Plain Township, says the implantable cardioverter defibrillator (ICD) has greatly improved his quality of life. "Now I wake up feeling refreshed." One of the devices is shown below.

KALAMAZOO -- The first day of November Steve Barnhart woke with a start.

He wasn't sure what had happened. Maybe, he thought, it was just a bad dream.

In a way it was, although he was lucky to wake up from it.

Implantable cardioverter defibrillator

His heart went into ventricular tachycardia -- wildly misfiring at more than 100 beats a minute -- and then into cardiac arrest. If it had happened a few weeks earlier, he could have died in his sleep.

But a month earlier, Barnhart had had an implantable cardioverter defibrillator placed in his chest. When his heart went into tachycardia, the ICD shocked his heart back into a normal rhythm.

"I was totally asleep and not aware that anything (like tachycardia) was happening," said Barnhart, a 57-year-old retiree who lives on a small farm in Gun Plain Township.
Several days later, Barnhart was in his cardiologist's office for a checkup when he mentioned that strange night to the ICD technician.

"She went back and looked at the history (of the device) on the computer," he said. "She could tell the minute the heart started acting irregularly, when it charged and shocked my heart back to sinus rhythm. It saved my life."

External vs. internal

Most people are familiar with defibrillators from popular media, which show emergency-room doctors and nurses pushing "crash carts" and using external defibrillators to shock patients' hearts back into normal rhythm.

Implantable defibrillators have been in existence since the 1980s, but the early devices were so large they had to be situated in a patient's abdomen, said Dr. Xiaoke Liu, the cardiologist who implanted Barnhart's ICD. Liu joined the local Heart Center for Excellence six months ago, coming from the Mayo Clinic.

Dr. Xiaoke Liu implanted a defibrillator in Steve Barnhart on Oct. 1 that saved his life just a month later.

Newer implantable defibrillators are only a few inches square and are placed near the collarbone, Liu said.

Defibrillators are not used to treat heart attacks, which occur when the blood flow to the heart becomes blocked by a blood clot and heart muscle can be damaged by lack of oxygen.

Defibrillators are used to treat ventricular fibrillation, in which the heart's lower chambers contract irregularly, causing the heart to pump little or no blood to the rest of the body, and ventricular tachycardia, such as Barnhart suffered.

"More than half of all heart patients die from these fast rhythms," Liu said. "Your heart is moving like a bag of worms. If that happens, your chance of survival is abysmal."

How ICDs work

An ICD provides continuous monitoring of the heart. When it detects an irregular heartbeat, it automatically shocks the heart in an attempt to restore a normal rhythm.

"Basically, it resets everything and stops that dangerous rhythm," Liu said.

An ICD comes with a transmission device that is kept at a patient's bedside. During the night, the transmitter collects data from the ICD, which is then sent to a central site and can be reviewed by a patient's doctor or other medical staff.

The devices are battery-operated, and the batteries generally last seven to 10 years.
Who qualifies and how effective are the devices?

Patients who qualify for ICDs generally are at high risk of death, having already suffered a previous heart incident, demonstrating weakened heart muscles or having a documented history of diagnosed irregular heart rhythms, Liu said.

ICDs, when combined with drug therapy, reduce deaths by 24 percent, according to the U.S. Agency for Healthcare Research and Quality. Other studies indicate that the reduction in deaths from sudden arrhythmia may be somewhat offset by increases in other heart-related deaths in patients with arrhythmia.

The AHRQ says the biggest challenge in the use of ICDs is identifying the best patient candidates.

The implantation surgery itself carries little risk and can usually be handled on an outpatient basis, although sometimes it requires an overnight stay, Liu said. During the surgery, the ICD is implanted in the chest, and wires leading from the device are implanted in the muscles of the heart.

Barnhart said his ICD not only saved his life that night in November, but has greatly improved his quality of life. Before receiving it, he was fatigued, weak and generally felt ill.

"Now I wake up feeling refreshed," he said. "I can go about the little things I do on the farm. I just feel a lot better."