Sometimes it pays to be out of sync. A new study shows that intentionally throwing off the timing of a heart's contractions can effectively treat a failure to pump sufficient blood.
In about a quarter of the five million Americans with the condition known as heart failure, the organ's chambers fail to contract in perfect synchrony. When pacemakers are implanted to restore favorable timing—known as cardiac resynchronization therapy—the heart often ends up stronger than in heart failure patients who never had out-of-step contractions. In essence, moving from dyssynchrony to synchrony seems to be beneficial. That observation led David Kass, who directs the Johns Hopkins Center for Molecular Cardiobiology, to a tantalizing question: Could heart failure patients with regular contractions benefit from a little discord?
To answer the question, Kass and his colleagues placed pacemakers into 23 dogs, 17 of which were induced into heart failure. Then, for six hours a day, the pacemaker in eight of the experimental animals forced the right side of the ventricle to contract earlier than the left side. For the rest of each day, the device reverted to synchronized pacing.
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After four weeks, key indicators of heart health proved markedly better in the dogs with pacemakers programmed for a period of irregular contractions. Their hearts pumped blood more forcefully, and proteins responsible for contractions and muscle structure were more abundant. The results, published last December in Science Translational Medicine, “fly in the face of our conventional thoughts about cardiac resynchronization therapy,” says George Thomas, a cardiologist at NewYork–Presbyterian Hospital and Weill Cornell Medical College who was not involved with the study.
The treatment can be likened to the body's reaction following a vaccination. Just as an injection of a weakened or partial virus triggers a protective immune response, exposing the heart to a “dose” of dyssynchrony fortifies its functioning. Kass plans to study the approach in humans in a year or so, but other cardiologists have already taken notice of the preliminary results. “It's a very thought-provoking, original idea,” says David Frankel, who treats heart failure at the University of Pennsylvania. He thinks many patients could benefit from a break in the monotony.