Relation between the Peak Acceleration of Aortic Blood Flow and End-distolic Aortic Pressure in Intact Dogs

Abstract

A quantitative analysis based upon the equivalent circuit model of the left ventricle- systemic circulation was performed to study the afterload dependency of the peak acceleration of the left ventricular ejection flow. Also, in experiments with conscious dogs, the left ventricular pressure, the left ventricular minor axis dimension, and the aortic flow were measured using implanted transducers before and after quick inflation of a pneumatic occluder (balloon), circumferentially placed in the descending aorta, to induce changes of the peripheral impedance with a constant ventricular contractile state and preload. The present circuit analysis shows that the peak acceleration at the onset of the impulse-like pressure source is dependent upon the factors of the ventricular performance, and also on peripheral conditions. The present animal experiments in unanesthetized dogs confirmed the above theoretical results by showing significant changes of the peak acceleration of aortic flow after changes of the peripheral impedances. (1052±431(cc/sec2 ), p< 0.001 during aortic occlusion and -1833 ± 799(cc/sec2 ), p-; 0.001 during aortic release) Also, as suggested in the analysis, the high negative correlation coefficients( -0.74, p<O.Ol during aortic occlusion and -0.83, p<O.Ol during aortic release) between the peak acceleration and the end diastolic arterial pressure were shown in the animal experiments. The present study shows that the peak acceeration of the left ventricular blood flow may be used as an index of the left ventricular performance, only when one compares the ventricular function at constant input impedance condition.