Is Coronary Sinus Blood Oxygen Tension Behavior Determined by Myocardial Oxygen Tension Variation during Cardiac Reperfusion?

Abstract

The relationship between coronary sinus blood oxygen tension (CSPO₂) and myocardial oxygen tension (MPO₂) variations during cardiac ischemia and reperfusion was studied in anesthetized open-chest dogs. Oxygen tension was measured by a polarographic method. Ischemia resulted in a slightly decreased CSPO₂ and a more pronounced reduction of MPO₂. After reperfusion the CSPO₂ rose rapidly and transiently before it returned gradually to the control level. By contrast, during the recovery period, the MPO₂ increased slowly, with recovery occurring long after the peak of CSPO₂. These data suggest that during the reperfusion phase, the CSPO₂ variation is probably due to opening of the myocardial arteriovenous shunts instead of an increase of flow through the myocardial capillary bed.