title: Energy demand of cardioplegically perfused human hearts.
abstract: Human adult hearts with aortic valve disease (n = 20) and hypertrophic obstructive cardiomyopathy (n = 1) were perfused intraoperatively with cold histidine buffered Bretschneider solution. During a seven minute cardioplegic perfusion the temperature level, the electrolyte level, the resistance of the left (LCA) and right coronary artery (RCA), and myocardial O2 consumption were analysed. Equilibration of K+ was terminated shortly after the start of the perfusion while Na+ equilibration lasted for about 5 minutes. Resistance of RCA did not change significantly, but that of the LCA was diminished significantly (p less than 0.025) within the perfusion period indicating a delayed washout of calcium from the extracellular space. Myocardial O2 consumption was reduced from 2.71 ml/min (1. minute) to 1.51 ml/min (4. minute) to 0.93 ml/min (7. minute) although the temperature had reached a low level after 3 minutes. The difference between 4. to 7. minutes is significant (p less than 0.001). By our results it is concluded that in adult hearts high-volume cardioplegic perfusion at a flow rate of 1 ml/min X gm at a perfusion pressure of 40 to 50 mmHg should be performed for at least 6 to 7 minutes to achieve a sufficient intra-ischemic myocardial protection.
mesh_terms: D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000378:metabolism / Q000601:surgery; D002312:Cardiomyopathy, Hypertrophic / Q000378:metabolism / Q000601:surgery; D003331:Coronary Vessels / Q000503:physiopathology; D004573:Electrolytes / Q000378:metabolism; D004734:Energy Metabolism; D005260:Female; D006324:Heart Arrest, Induced / Q000379:methods; D006349:Heart Valve Diseases / Q000378:metabolism / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D010313:Partial Pressure; D010477:Perfusion / Q000379:methods; D013997:Time Factors; D014655:Vascular Resistance
chemical_list: D004573:Electrolytes