Myocardial oxygen metabolism of the right ventricle with volume loading and hypoperfusion

A comparison of blood flow and myocardial O2 consumption (MVO2) in the right and the left ventricles was made in dogs whose chests had been opened. The effect of volume loading by arterio-venous and arterio-left atrial shunts, and the effect of ventricular hypoperfusion by rapid removal of blood were examined in the presence and absence of the pericardium. Blood flow per unit myocardium was greater in the left anterior descending coronary artery (LAD) than in the right coronary artery (RCA), 75 +/- 4.3 vs. 46 +/- 2.8 (mean +/- SE) ml/min per 100g, respectively. Similarly, the myocardial O2 extraction ratio (EO2) was 59 +/- 2% in the left ventricle and 43 +/- 3% in the right ventricle (p less than 0.001). The MVO2 was greater for the left than for the right ventricle, 8.0 +/- 0.6 vs. 3.5 +/- 0.3 ml O2/min per 100g. Volume loading to both ventricles by arterio-venous (AV) shunt increased MVO2 of the right ventricle by augmented EO2 in addition to a rise in the coronary arterial blood flow. Decrease in aortic pressure by rapid removal of blood increased EO2 in both ventricles. The increments of EO2 were greater in the right ventricle than in the left ventricle, 54 vs. 31% (p less than 0.01). When the pericardium was closed with suture, right and left end-diastolic pressure rose, but EO2 and coronary blood flow of both ventricles did not change. We conclude that reserve capacity of myocardial O2 extraction was greater in the right ventricle than in the left ventricle.