CORONARY BLOOD FLOW AND CARDIAC OXYGEN CONSUMPTION IN UNANESTHETIZED DOGS

Abstract

The coronary blood flow, oxygen consumption and efficiency of the left ventricle were measured in 27 e''xpts. on 14 unanesthetized dogs. The oxygen content of coronary sinus blood ranged from 2.2 to 7.3 vol. %. The coronary arteriovenous differences averaged 11.9 vol. %. The coronary blood flow and cardiac oxygen consumption per 100 g. of left ventricular muscle showed marked variation (from 80 to 220 cc. [sigma] 35, and from 9.5 to 24.0 cc. [sigma] 3.5, respectively). Since left ventricular flow and oxygen consumption per unit heart wt. varied inversely with body wt., the marked variations observed were probably the result of different ratios of surface area/body wt. The coronary blood flow and oxygen consumption of total ventricular muscle ranged from 52 to 103 cc./min. [sigma] 13.1) and from 6.04 to 15.1 cc./min. ([sigma] 2.2), respectively. These values showed considerably more uniformity than those obtained per unit of heart wt. The left ventricular efficiency ranged from 20 to 38%. These values were considerably lower than those previously reported on anesthetized dogs using the nitrous oxide method, but agreed well with those obtained on normal man. The high degree of correlation between left ventricular oxygen consumption and left ventricular blood flow/100 g. with left ventricular wt. and between total left ventricular blood flow and cardiac output are indirect evidence of the validity of the nitrous oxide method for measurement of coronary blood flow.