AM radio waves, which have brought so many songs that spoke of love, are now being used to zap the hearts of those whose rapid heartbeats can't be treated with drugs, scientists said.

The radio-wave method of treating arrhythmia is safer than electric shock or surgery, researchers reported at the American College of Cardiology's annual meeting, which ended Thursday.The technique, being tried by doctors in San Francisco and Europe, "is like using a ball peen hammer instead of a sledgehammer," said Dr. Douglas Zipes, a professor at Indiana University School of Medicine.

Like radio waves, alcohol also is being applied directly to the heart by catheters - thin, long tubes that are inserted through blood vessels - to halt various abnormal heart rhythms, Zipes said.

So far, Dr. Jonathan Langberg and colleagues at the University of California, San Francisco, have used radio waves to control rapid heartbeats in 10 patients whose abnormal heart rhythm couldn't be treated with drugs.

It failed on six others, four of whom then were treated successfully with electrical shocks.

Langberg said about 1 million Americans suffer from supraventricular tachycardia, which can make the heart beat up to 200 times a minute, causing patients to faint, suffer shortness of breath, lightheadedness and occasionally death.

The researchers hope to use radio waves to treat the much more serious rapid heartbeat called ventricular tachycardia, which kills about 500,000 mostly older Americans a year.