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Take heart: ventricular tachycardia cure.

Take heart: Ventricular tachycardia cure

An improved understanding of the electrical flaws causing rapid heartbeats -- or tachycardia, which means literally "heart hurry" -- has led cardiologists to develop an innovative treatment for one potentially fatal form of the condition. Cardiologists successfully used electrical shocks to treat seven patients suffering from severe ventricular tachycardia, an abnormal rhythm of the heart's lower pumping chambers, according to a report in the August CIRCULATION.

Such arrhythmias can be difficult to treat with drugs or open-heart surgery, but with electrical shock administered by catheter, Patrick Tchou and his colleagues at the University of Wisconsin in Milwaukee appear to have eliminated the patients' tachycardia. Other researchers previously used a similar approach on arrhythmias affecting the heart's upper chambers.

In pretreatment studies, the Wisconsin scientists pinpointed the patients' tachycardia to a specific conduction defect in the electrical impulses that cause the heart's lower chambers to contract.

"Through excellent deductive reasoning," observes Melvin M. Scheinman of the University of California, SAn Francisco, in an accompanying editorial, Tchou's group determined the mechanism of the tachycardia. Because the normal circular flow of electricity in these patient's hearts was interrupted by a slowing of conduction in the left bundle branch, consisting of specialized conducting tissue, they reasoned that the right bundle branch would be critical to maintaining the tachycardia, and they destroyed it.

After placing an electrode catheter near the right bundle branch -- a "well-defined and accessible electrical landmark" -- of anesthetized patients, they administered two electric shocks with the catheter tip serving as the cathode. Following treatment, all the patients recovered from their tachycardia and accompanying fainting spells, although two patients subsequently died of other heart conditions. The rest remained active and symptom-free as much as 55 months after the procedure.

While this particular arrhythmia is not common, it occurs more often than is recognized, the researchers say, and the new treatment not only is "relatively safe" but is "probably preferable" to standard long-term drug treatment, which carries major side effects. All the patients who had tried the drug treatment (six of seven) either could not tolerate it or failed to respond.

While praising the study as a "landmark," Scheinman does say the treatment warrants further critical appraisal before being accepted into cardiologists' clinical arsenal. He cautions that the defect itself can be difficult to detect, even by the most experienced electrophysiologists, and that serious damage to other tissues could occur during treatment. "Application of this technique," he warns, "is not for the novice!"

Scheinman concludes that the discovery nonetheless provides "a potential Rosetta stone" for more precise understanding of the circuits of ventricular tachycardia, and in a field where most treatment remains palliative, it may open the way for further curative techniques without the need to resort to open-heart surgery.
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Author:Eron, Carol
Publication:Science News
Date:Aug 27, 1988
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