You can live with some heart arrhythmias; others left unattended will kill you.

But all can be treated, according to Dr. John D. Day and Dr. J. Peter Weiss, who will address heart arrhythmia during tomorrow's Deseret Morning News/Intermountain Health Care Hotline. The two cardiologists with the Utah Health Clinic Arrhythmia Service at LDS Hospital will take phoned-in questions from 10 a.m. to noon.

The heart is an "electric" muscle, and an arrhythmia is an electrical problem that disrupts its ability to beat at a steady pace. Just as wiring in the house can go awry, so can the heart's circuitry. Whether arrhythmia is caused by a short circuit or an extra pathway, the result is typically either a heartbeat that's regular but too fast or slow, or an irregular, even chaotic heartbeat.

After medical history, blood pressure and overall health are assessed, other tests may be run, including electrocardiogram (ECG/EKG), an echocardiogram, a "stress test" (an ECG while exercising), use of a monitoring device, tilt-table testing or an electrophysiology study.

Treatments vary, from use of medication to ablation, where the circuitry is altered by cauterizing it, or use of an implantable device like a pacemaker or defibrillator.

"You can live with atrial arrhythmia," said Day. "Most people feel the arrhythmia, but particularly in the older age group, they just feel tired and don't know why."

Supraventricular tachycardia (SVT), which people are born with although they don't become arrhythmic until younger adult life or later, is caused by an extra electrical pathway and features a very fast and regular heartbeat — in most cases, between 130 and 220 beats per minute. It causes shortness of breath, chest discomfort and other symptoms, such as dizziness or light-headedness.

SVT is episodic, with the heart rate going from 60 to 220, for instance, suddenly, but it tends to happen more often and last longer as people get older. An episode may send someone to the emergency room for medication to stop it.

It's easily curable using cardiac catheter ablation. The cardiologist goes in through the vein in the leg, identifies the extra electrical pathway and shuts it off permanently by cauterizing it. In about 97 percent of cases, that's the end of it, Day said.

Other atrial arrhythmias develop over time. The most common, atrial fibrillation, can cause strokes.

A recent study said one in four people over their lifetime will develop atrial fibrillation, which results in total electrical chaos of the two upper chambers of the heart. Its causes are high blood pressure, heart failure and age.

Atrial fibrillation ended Larry Bird's career playing basketball, and its complications killed Richard Nixon. Bill Bradley experienced recurrent episodes while running against Al Gore for the Democratic nomination in 2000.