DEAR DOCTOR K: I have a heart arrhythmia. My doctor wants me to get an ICD. What do I need to know before agreeing to get one?
DEAR READER: ICD stands for "implantable cardioverter-defibrillator." It is a small device that is surgically placed in your body. An ICD can save your life -- but it can also complicate your life.
Why was the ICD developed? Sometimes the heart develops dangerous irregular rhythms. Two, in particular, are life-threatening. The most dangerous is ventricular fibrillation (VF). When a heart develops VF, it stops pumping. It just quivers; it's in cardiac arrest. With no blood circulating to your brain, you lose consciousness. If no blood reaches your brain for more than 4 minutes, your brain dies.
Another dangerous rhythm is ventricular tachycardia (VT). Your heart beats rapidly, and your blood still circulates -- though less effectively than with a regular rhythm. Unfortunately, if VT is not corrected, it often turns into VF.
About 60 years ago, Harvard doctors invented the defibrillator, a machine that delivers a shock to the heart. They showed that the shock could quickly return a dangerous heart rhythm to normal. The shock was delivered by two paddles placed on a patient's chest. Obviously, the defibrillator could help you only if your dangerous heart rhythm was diagnosed and treated within minutes of its starting. You had to be in a medical setting, or emergency medical technicians had to get to you very quickly.
In recent years, machines to deliver these shocks are also located at airports, on airplanes and in other public places. Still, most people who develop VT or VF are nowhere near a defibrillator.
Enter the ICD, which has two basic functions. First, it reads your heart rhythm and spots a potentially dangerous one. Second, it sends a jolt of electricity to your heart muscle to end the dangerous rhythm and restore a normal rhythm. The only people for whom an ICD is recommended are people who have had VT or VF, or who have a heart condition that greatly increases their risk of developing these dangerous rhythms.