Phasic and Mean Blood Flow in the Canine Septal Artery and an Estimate of Systolic Resistance in Deep Myocardial Vessels

Abstract

Phasic flow in the canine septal artery was recorded with an orifice meter supplied by pulsatile aortic pressure. Flow patterns were recorded when right ventricular pressure was normal and contrasted with those following elevation of right ventricular pressure in order to minimize the dynamic effect of the superficial component of the artery. Results indicate that elevation of right ventricular pressure increases the early systolic backflow, largely prevents mid-systolic forward flow, and accentuates early diastolic flow. It is suggested that this pattern does not represent that in arterioles in deep layers of the myocardium. In other experiments the septal artery was perfused through an orifice meter at variable pressures to determine the pressure required to negate mid-systolic flow at high right ventricular pressures. The results indicate that pressures considerably above aortic or right ventricular systolic pressures are required to generate forward mid-systolic septal flow. The mean septal flow was quantitated in terms of total common left inflow. It was found that an average of 16.0% of common left flow enters the septal artery. The significance of this has been discussed in terms of its relationship to the venous drainage of common left coronary arterial inflow.