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Using radiofrequency energy
to disconnect misbehaving muscle cells from the heart can treat the heart-rhythm
disorder atrial fibrillation in some patients.
Atrial fibrillation is a very
chaotic and irregular heartbeat that occurs in the upper chambers of the
heart, called the atrium. While the heart-rhythm disturbances
of atrial fibrillation are not themselves life-threatening, the condition
does raise the risk that blood clots will form and possibly lead to a
stroke.
The muscle "sleeves"
that envelop the pulmonary veins -- blood vessels that carry oxygenated
blood from the lungs to the heart -- are frequently the source of these
heart-rhythm abnormalities. Signals, or extra beats, originating from
the muscle sleeves can trigger atrial fibrillation.
Atrial fibrillation can be
treated with drugs or an
electric jolt to shock the heart back into normal rhythm. Attempts
have also been made to treat the condition by ablating, or destroying,
some heart muscle cells and thus isolating the source of the extra beats
from the rest of the heart. However, patients treated with this technique
often require additional treatments.
Researchers note that past
ablation attempts only targeted veins that were shown in diagnostic tests
to be a source of abnormal heart rhythms. But these tests may not always
identify source of the extra beats.
Because these extra heartbeats
may originate from any of the four pulmonary veins, in the study they
electrically isolated at least three of the four pulmonary veins and destroyed
those cells with radioablation.
After 5 months of follow-up,
70% of patients
with intermittent atrial fibrillation were free from recurrent irregular
heartbeats without the need for an anti-arrhythmic drugs. An
additional 13% of patients had greater than 90% improvement in their symptoms
either without or with an anti-arrhythmic drug that was previously ineffective.
In patients with persistent
atrial fibrillation -- meaning the condition had been present for months
to years -- only 29% were either free of recurrent atrial fibrillation
or had a significant improvement after 5 months of follow-up.
Circulation January 29,
2002;105
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