Outflow from the left and the right coronary artery into the coronary sinus in the dog heart in situ.

The fractions of the left and the right coronary arterial flow determining coronary sinus flow (facs, facd) were measured in the open-chest dog. Both coronary arteries were isolated and perfused at the same pressure, while the sinus outflow was isolated and drained against the prevailing mean pressure in the right atrium. The fractions were determined by injecting 51Cr labeled erythrocytes into each coronary artery selectively and measuring the total resulting radioactivity in the sinus blood. In addition, they were estimated from flow measurements. The values of facs and facd were found to approximate 0.70 and 0.02 respectively. The variability between the different dog hearts was considerable and it was demonstrated that they were not intercomparable with respect to their coronary flow distribution.