We've all seen it on ER. The heart monitors go crazy, doctors rip the patient's shirt open and slap paddles on his chest, someone yells "Clear!" and the doctor jolts the patient with an electric current.
It's a dramatic scene, but many people benefit more quietly from the same machine, called a defibrillator, every day. Implanted in the chest or shoulder, smaller versions of the emergency-room equipment are being used to detect an irregular heart rate and instantaneously deliver an electric current.
The smallest defibrillator developed to date was cleared Monday by the Food and Drug Administration and will be sold commercially this spring. The GEM II DR, the latest implantable defibrillator developed by Medtronic of Minneapolis, measures only 40 cubic centimeters, but can still deliver up to 30 joules of energy to control a runaway heart rate. The previous model, the first GEM DR, was 62 cubic centimeters. It runs on a smaller battery and capacitor than its predecessors by using a small amount of energy to deliver a large voltage.
The smaller the better, cardiologists say.
"The significant point is that the device has a much smaller volume. Implanted just under the skin in the pectoral region, it leaves no visible signs," said Jack Keimel, vice president of defibrillator systems operations at Medtronic.
The size of defibrillators has always been a drawback, said Mark Sweesy, technical director at the Arrhythmia Technologies Institute in Greenville, South Carolina. "The smaller it is, the less problems we'll see with infection, erosion, and surgery."
Heart disease is the No. 1 killer in the United States. The majority of these deaths are caused by sudden cardiac arrest -- the result of rapid ventricle rhythms which defibrillators can control.
"It's a life-saving device, and it's one that could reverse the statistics," Sweesy said. "The more they can simplify the implantation, the more people can benefit from a defibrillator as a prophylactic."
Most people who suffer sudden cardiac arrest don't survive their first episode. Researchers want to target this high-risk group with a prophylactic device.
