Hemodynamic Studies on Synchronized Arterial Counterpulsation

Abstract

Synchronized Arterial Counterpulsation, advocated by Harken and associates in 1961, is a type of assisted circulation for left-sided heart failure. With this procedure performed, the blood ejected from the left ventricle is sucked into a blind pump ventricle during left ventricular ejection by means of a pump which operates in synchronization with cardiac activity. During ventricular diastole the blood is then returned to the arterial tree by the pump. Thus, an inversion of phases of the aortic pressure curve takes place by this procedure. Using healthy adult mongrel dogs, the author has made attempts to investigate the hemodynamic effects of Synchronized Arterial Counterpulsation in which an arterial cannula was inserted through the abdominal aorta into the aortic arch. The pump used in the studies was the Davol Heart Pump Model 8500, which is able to operate in synchronization with the electrocardiographic R wave and is regulatable with regard to its systolic delay from the R wave, its systolic and diastolic duration and its stroke volume. Total right ventricular bypass was performed in these experiments for measuring cardiac out-put, which was accounted for output of the pump for the bypass, Sigmamotor Model TM-2. The following parameters were adopted for evaluating the hemodynamic effects of Synchronized Arterial Counterpulsation : the pressure curves in the aorta and the left ventricle, cardiac output, coronary sinus blood flow, myocardial oxygen consumption, the Tension-Time Index, the external and internal work of the left ventricle, efficiency of the left ventricular work, and others. Therefore, in order to examine the changes in these parameters by this procedure, aortic and left ventricular pressure as well as cardiac output were measured and recorded, and the aortic and coronary sinus blood was sampled to be examined. All of the above-mentioned parameters were satisfactorily monitored in 12 dogs, which were divided into group I and II according to results. In group I, 6 dogs showed a decrease in left ventricular pressure, a decrease in myocardial oxygen consumption and an increase in coronary sinus blood flow. The remaining 6 dogs, classified as group II, did not show at least one of the changes in three parameters.