Harvard Heart Letter

Dual-chamber pacemaker helps heart failure

A heart attack, high blood pressure, and other insults can reshape the heart in ways that derail the "beat now" signals that are vital to a healthy heartbeat. The two lower chambers, the right ventricle and left ventricle, should contract and relax together. In many people with heart failure, though, they don't. This loss of synchronized squeezing costs the heart some of its pumping power.

A biventricular pacemaker can fix this problem. It sends carefully timed signals that make the right and left ventricle contract and relax in unison. This is called cardiac resynchronization therapy. Biventricular pacemakers were initially approved for people with severe heart failure. Greater experience with them will almost certainly broaden the population of folks who could benefit from one.

illustration of heart with pacemaker installed

Results of an international trial suggest that combining a biventricular pacemaker with an implantable cardioverter-defibrillator (ICD) — a device that can shock the heart out of a potentially lethal rhythm — helps prevent deaths from sudden cardiac arrest and hospitalizations for heart failure better than an ICD alone (New England Journal of Medicine, Dec. 16, 2010). The downside of this double therapy is an increase in hospitalizations due to problems with the devices.

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