Coronary Sinus Pressure: A Condition per Se of Return Volume via the Coronary Sinus in the Healthy Animal? Surgical Considerations in Atriopulmonary Anastomosis Procedures

Abstract

In order to test the hypothesis of the "vascular waterfall" mechanism in coronary venous circulation, the role of coronary sinus pressure in the regulation of coronary return volume (CRV) via the coronary sinus (CS) was studied in healthy animals. An experimental model of pressure regulation in the CS was prepared and aortic and left atrial pressures, EKG, and the cardiac output (measured by thermodilution) were recorded. The return volume via the CS was measured at CS pressures of 10 or less, 15, 20, and 25 mm Hg or more, for a total of 36 determinations. Overall, increased CS pressure did not produce significant changes in aortic and left atrial pressures, heart rate, cardiac index, or CRV via the CS. When CS pressure was 25 mm Hg or more, however, there was a significant decline in the average CRV via the CS. Nevertheless, stepwise variant regression showed that the CS per se does not condition the volume of coronary return via the CS. The authors' results suggest that in healthy animals, the hypothesis of the "vascular waterfall" mechanism in coronary venous circulation is not valid. Thus, in correcting congenital cardiac malformations by use of atriopulmonary anastomosis procedures, there is no justification for employing techniques that ensure CS drainage into the left atrium in order to avoid the hemodynamic repercussions attributable to the hypothesis of the "vascular waterfall."