DALLAS, Jan. 29 – Smart bombs are touted for their ability to precisely target and destroy an enemy. Now equally “smart” technology is being used by heart experts to target and destroy cells that trigger the irregular heart rhythm called atrial fibrillation, according to a report in today’s rapid access publication of Circulation: Journal of the American Heart Association.
In atrial fibrillation (AF) the two upper chambers of the heart, the atria, beat erratically, causing blood to pool inside the chamber and become stagnant. When this occurs, blood clots may form and cause strokes.
In a study of 70 people with AF, Hakan Oral, M.D., assistant professor of medicine at the University of Michigan, Ann Arbor, used radio frequency energy delivered from a catheter tip to locate and destroy cells that cause the extra heartbeats leading to AF. All abnormal beats were eliminated and a normal rhythm was restored in more than 80 percent of the people in the study who had intermittent, or paroxysmal, AF. The treatment, called radio frequency ablation, was less effective for those with persistent AF.
“By zapping the cells this way, we disconnect cells with abnormal electrical activity from the rest of the heart,” says Oral. “When those misfired electrical impulses reach the atrium, they can trigger atrial fibrillation.”
Palpitations and rapid heart beat are symptoms of AF. Devices called defibrillators are used to shock the heart back into a normal rhythm, or medicines called antiarrhythmics are used, says Oral. These antiarrhythmic medicines are also used to prevent recurrences of AF. However, drug therapy may not be effective in all patients and may be associated with side effects. In addition to antiarrhythmic treatment, medicines that thin the blood are used to prevent blood clots, which are common in people with AF.
Oral says the only way to “cure” AF is to eliminate the source of the problem: those cells that trigger the extra beats. “Earlier studies show that most of these signals appear to originate in the pulmonary veins that carry clean, oxygenated blood from the lungs to the left atrium. These cells, located within a few centimeters of the opening into the left atrium, can spontaneously fire and cause the extra beats,” he explains.
“The best strategy for ablation is to electrically disconnect the muscle of the vein from the rest of the heart by precisely identifying the sites around the circumference of the pulmonary veins where there is ‘communication’ between the vein and the atrium,” he says.
In the new study, Oral and his colleagues attempted to ablate at least three of the four pulmonary veins in a series of 70 patients with either paroxysmal or persistent AF who had not responded to drug therapy.
Fifty-seven men and 13 women participated. Their averag
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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