Tone-dependent coronary arterial-venous pressure differences at the cessation of venous outflow during long diastoles

S Satoh, F J Klocke, J M Canty
1993 Circulation  
Background. The origin and magnitude of the back pressure opposing diastolic coronary inflow remain controversial. The arterial pressure at which coronary inflow stops during a prolonged diastole, ie, "zero-flow pressure," is higher than coronary venous pressure. However, because of capacitive discharge as distending pressure falls, flow at the microcirculatory level exceeds inflow, and coronary outflow ceases later than inflow. If coronary arterial pressure continues to exceed venous pressure
more » ... ed venous pressure at the point of venous flow cessation, zero-flow pressure cannot be an artifact of capacitive discharge. Methods and Results. Coronary inflow and outflow, arterial pressure, and right atrial pressure have been measured during long diastoles in closed-chest dogs chronically instrumented with volumetric flow probes on the great cardiac vein or coronary sinus as well as the circumflex artery. Although venous outflow continued for 1 to 4 seconds after arterial inflow ceased, coronary artery pressure at the point of venous flow cessation (PN=0) always exceeded right atrial pressure (13±1.3 mm Hg [SEMI vs 6±0.7 mm Hg, P<.001). When vasomotor tone was augmented using vasopressin, the diastolic pressure-flow relation shifted to the right, with Pf"o increasing to 21±2.4 mm Hg despite an unchanged right atrial pressure (6±0.5 mm Hg). Conclusions. Transcoronary pressure differences persist when venous outflow stops and are larger when
doi:10.1161/01.cir.88.3.1238 pmid:8353885 fatcat:h5h7mizgxjhl3mhe5sqxfi5lym