Severe cases of irregular heartbeat may require a procedure called ablation, which destroys a group of "misfiring" cells to stop abnormal electrical impulses that cause erratic heartbeats.

Investigators aimed at cells in the pulmonary veins that carry blood from the lungs to the heart. In the clinical part of the study, they ablated the misfiring cells with 100 percent accuracy. In 84 percent of the pulmonary veins treated, electrical pulses ceased after just one set of laser treatments. Three months after treatment, 90 percent of the treated veins remained inactive.

Unlike other catheters that rely on X-rays for visual guidance, in the new treatment doctors use a slender instrument called an endoscope that provides continuous real-time images. This allows investigators to aim the laser at precise locations in the pulmonary veins. The investigators destroyed cells in an overlapping pattern to completely "disconnect" them and prevent new electrical connections from forming later.

The study's clinical component included 27 patients, average age 53, two-thirds male, with diagnosed intermittent, abnormal heartbeat (called paroxysmal atrial fibrillation, or PAF). All patients had tried at least one drug that did not relieve their symptoms.

For the animal model, the scientists examined pigs because their hearts are structured similar to humans. The investigators inactivated abnormally functioning pulmonary veins 97 percent of the time after the first set of laser-energy treatments. Four weeks later, 80 percent of the ablated veins were still inactive.

Additional research is needed to determine long-term safety and efficacy of balloon-guided, laser catheter, researchers said.

Note: If no author is given, the source is cited instead.

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