The efficacy of blood cardioplegia is not due to oxygen delivery.
Twenty-seven canine hearts instrumented with ultrasonic dimension crystals underwent simultaneous determination of stroke work and myocardial oxygen consumption during incremental volume loading on right heart bypass before and 30 minutes after 2 hours of cardioplegic arrest at 10 degrees C. Three cardioplegic solutions were used: Hematocrit values were 17.0% (group I), 8.2% (group II), and 0% (group III). In all groups the slope of the linear stroke work versus end-diastolic volume relationship, a measure of contractility, was unchanged after ischemic arrest. However, the myocardial oxygen consumption for basal metabolism was increased an average of 25.5% after arrest with plasma (group III). Since the plasma concentration in all three groups was identical, and the oxygen available to the hearts during ischemia was the same in groups II and III, the efficacy of blood-based cardioplegic solutions cannot be attributed to a plasma component or to the greater oxygen-carrying capacity of the red blood cell. Future studies should attempt to identify the salutory entity of the red cell responsible for preservation of myocardial oxygen consumption efficiency.
Illes
R W
RW
Department of Surgery, University of Illinois, College of Medicine, Chicago.
Silverman
N A
NA
Krukenkamp
I B
IB
Yusen
R D
RD
Chausow
D D
DD
Levitsky
S
S
D000818:Animals; D001769:Blood; D001794:Blood Pressure; D002314:Cardioplegic Solutions; D004285:Dogs; D004734:Energy Metabolism; D006339:Heart Rate; D006400:Hematocrit; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D013318:Stroke Volume
D002314:Cardioplegic Solutions; D010100:Oxygen