Effect of proximal and distal coronary pressure change on the resistance of stenotic coronary segment.

While dynamic changes in the resistance of stenotic coronary segments were recently proposed by several investigators, the mechanisms of these changes are obscure. This study was conducted to correlate changes in coronary pressure distal to the stenosis to dynamic changes in the stenosis resistance in the canine heart. Coronary pressure distal to the stenosis was raised by either proximal aortic pressure elevation or intracoronary blood infusion distal to the stenosis. The pressure rise resulted in a significant fall in the stenosis resistance. Distal coronary pressure drop induced by phlebotomy or removal of blood from the distal coronary bed caused the reverse effects on resistance. Linear regression analysis revealed a close relationship between changes in distal coronary pressure (delta DCP) and those in resistance of the stenotic coronary segment (delta RL) represented by the following equation; delta RL (dyne X cm-5 X sec X 10(-3)) = 0.50 X [delta DCP (mmHg)]-6.0 X 10(-2), r = 0.86, p less than 0.01. The results suggest that dynamic changes in stenosis resistance appear largely to be a function of the pressure changes distal to the stenosis.