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Effect of arterial counterpulsation on left ventricular volume and pressure.

MULLINS,~HARLES B., WINFRED L. SUGG,BRIAN M. KENNELLY, DAN C. JONES, AND JERE H. MITCHELL. Effect of arterial counterpulsatil>n on left ventricular volume and pressure. Am. J. physiol. 220(3) : 694-698. 197 1 .-The influence of arterial counterpulsation by means of the SIMAS circulatory assist device on left ventricular volume and pressure was studied. Fifteen studies in nine dogs were completed, with the control measurements being followed immediately by measurements made during counterpulsation with 20-ml volumes produced by the SIMAS pump. Mean aortic pressure and heart rate were maintained constant throughout the experiments. There was no significant change in left ventricular end-diastolic volume, end-systolic volume, stroke volume, or left ventricular end-diastolic pressure during arterial counterpulsation. Systolic pressure during ejection was decreased by counterpulsation sufficiently to cause a decrease in stroke work of the left ventricle. The decrease in left ventricular stroke work and in maximal rate of pressure rise (max dp/dt) from the same enddiastolic volume and pressure and the lack of a change in ejection fraction with a decreased afterload all demonstrate a decrease in contractility of the left ventricle. Even though left ventricular volumes were not changed, the decrease in pressure work and decrease in contractile state should cause a decreased myocardial oxygen demand.