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.
The symptoms are the same as far as chest discomfort and shortness of breath, but there's also the sense one is barely hanging on and could pass out. "It's a life-threatening arrythmia and you need to seek treatment very fast."
Treatment is an implantable defibrillator.
The shock it delivers saves lives, but it's not pleasant. That's why patients with ventricular tachycardia are increasingly opting for ablation to reduce the chance they'll need to be shocked by the device. That's one of the riskier ablation procedures, Weiss said.
With ablation, the doctor determines where the electrical problem is and cauterizes it. Ablation is also used with several types of atrial (upper heart chambers) arrhythmias.
There's also a rare condition where people develop what is called idiopathic ventricular tachycardia, which can occur in patients with otherwise-normal hearts. Most of the time, that's not life-threatening.
Patients who experience ab- normal heart rhythms need to let their physician know. It can be easily diagnosed. Weiss and Day recommend that patients over 65 make it a point to check their pulse at least a couple of times a year to see if it's irregular. If it is, it's important to see a doctor. Atrial fibrillation, for instance, is a major trigger of strokes.
Younger patients with a funny, fast or irregular pulse should find out why. And anyone with heart disease needs to know his ejection fraction.
Implantable defibrillators are not all that's exciting in pacing the heart. Cardiac resynchronization therapy, also called biventricular pacing, involves a type of device only recently available. Instead of pacing just the right ventricle, this can pace both the right and left side at the same time. It is proving a valuable treatment for heart failure, because the two sides stop working well together and this improves the heart's efficiency. It clearly boosts quality of life and probably longevity, Weiss said.
The "Cadillac device" is the biventricular defibrillator, which combines the best of both the defibrillator and the biventricular pacemaker, he said.
Another exciting development is cryoblation, which involves freezing rather than burning. Ablation uses radio frequency energy to burn tissue and once it's burned, it's burned. Cryoblation allows for a test run. Tissue can be frozen partway and if the results look good, it can be frozen completely to kill the tissue. If not, it can thaw and return to its previous state.
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