Premature Depolarization of Ventricular Cycle Suggested to Augment Cardiac Contraction

JAMA. 1964;190(11):36. doi:10.1001/jama.1964.03070240076040.
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Investigators at the National Heart Institute have developed a new technique for slowing ventricular heart rate and augmenting myocardial contractility by prematurely depolarizing the ventricular electrical cycle.

"Normally, each electrical cycle of ventricular depolarization is accompanied by contraction," Peter L. Frommer, MD, senior investigator, National Institutes of Health Cardiology Branch, said. "A spontaneous or induced premature depolarization produces a less forceful contraction and depolarization can actually be induced so prematurely that no discrete associated contraction occurs. However, this premature depolarization prolongs the period during which the ventricle is unresponsive to other electrical stimuli and augments myocardial contractility."

Frommer told the 17th annual Biomedical Engineering Conference that repeated premature depolarizations, one after each normal depolarization, generally suppressed ventricular arrhythmias and slowed the heart rate.

There are two methods of achieving premature depolarization, Frommer said. The first employs an external pacemaker that can induce both the primary and premature depolarizations.

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