Ventricular arrhythmias are simple. They get fixed or you could die.

Ventricular fibrillation, chaos in the heart's lower chambers, is one of the deadliest heart arrhythmias, according to cardiologists Dr. Peter Weiss and Dr. John Day. It leads to cardiac arrest and within seconds, the patient passes out. There's nothing to pump the blood. And without fast intervention, the patient becomes one of the 400,000 Americans who die each year from sudden cardiac arrest, the No. 1 killer in the Western world.

Heart arrhythmias and what can be done about them is the topic of today's Deseret Morning News/Intermountain Health Care Hotline. From 10 a.m. to noon, Day and Weiss will answer phoned-in questions on the topic.

Ventricular fibrillation used to be lethal unless someone was there to do cardiopulmonary resuscitation until an emergency medical response team arrived to shock the heart back into rhythm. Now, depending on where someone collapses, there might also be a public access defibrillator available. They're increasingly on hand in gyms, shopping malls, at golf courses and in companies with many employees.

Heart disease is far and away the leading cause of ventricular arrhythmias. A history of heart attack also increases risk.

There's a lot of confusion around heart attack, which results when an artery to the heart becomes blocked. Cardiac arrest is actually an electrical problem that destroys the heart's rhythm, sometimes kicked off by that plumbing problem.

Patients who are lucky enough to survive, Day said, get an implantable defibrillator, as do many patients who are deemed to be at high risk of suffering cardiac arrest, including people with a history of heart attacks, heart failure or other problems.

"Very few people are lucky enough to survive, so where we've moved now is to identifying patients. There is a marker of how weak a heart muscle is, called the ejection fraction. And in my view, it's as important as knowing your blood pressure or cholesterol," he said.

The ejection fraction, determined by echocardiogram, is the percentage of blood that goes into the heart that you're able to pump out with each heartbeat. Normal is about 60 percent. Anyone with an ejection fraction below 35 percent could benefit from a prophylactic defibrillator, according to the Food and Drug Admin- istration.

Ventricular tachycardia is an organized arrythmia in the lower chambers of the heart. It's very dangerous because it often degenerates into ventricular fibrillation. Many patients don't lose consciousness so they may be able to get help before it degenerates.