Effect of Ventricular Extrasystoles on Closure of Mitral Valve

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Abstract
Mitral valve function was assessed by roentgen videodensitometry. Mitral reflux was rare when single ventricular ectopic systoles were produced by electronic stimulation of the right or left ventricle at various times in the cardiac cycle. It was also rare during the compensatory pause after the ectopic systole or with the following postectopic systole. Recurrent ventricular ectopic systoles interposed once per cycle were associated with minor reflux when introduced in mid-cycle. Such extrasystoles occurred late enough in the cardiac cycle for the ventricle to relax after the primary systole and for the mitral valve to open before the extrasystole. The extrasystolic contractions were, however, weak and incapable of opening the aortic valve. When interposed early in the cardiac cycle, extrasystolic potentiation of the primary ventricular contraction occurred, and no or minimal mitral reflux was observed.