title: Effects of coronary washout on cardiac function during brief periods of ischemia and hypoxia.
abstract: Coronary washout has been shown effective in preserving metabolism during hypoxia, but its impact on mechanical function is unknown. To investigate this, experiments were conducted in a regionally perfused swine heart preparation (n = 19) in which oxygen (O2) delivery was repetitively restricted for short times (3 min) by randomly changing coronary flow (delta Qc) and/or arterial oxygen content (delta O2a) in the perfusion circuit. Recovery periods in each animal were at least 15 min between trials. Changes in metabolism and mechanics were expressed as a function of delta Qc and delta O2a (the two independent determinants) using linear regression equations. Significance and the ranking of importance for the two determinants were estimated by F testing, the t values of the respective regression coefficients, and partial regression analysis. Myocardial oxygen consumption (MVO2) was dependent on both flow and O2 content (MVO2% = 115.8 + 0.8 delta Qc% + 1.1 delta O2a%). However, regional mechanical function, including total shortening (TS) and an index of work (Indexw), was dependent only on arterial O2 content, e.g., TS% = 94.9 + 0.1 delta Qc% + 0.8 delta O2a% and Indexw% = 85.5 + 0.2 delta Qc% + 1.1 delta O2a%. In these latter relationships, O2 content ranked higher than Qc by factors of 7.39:1 and 5.34:1, respectively. Thus it was concluded that coronary washout offers no selective advantages in preserving average regional mechanical function during short-term O2 deprivation.
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D003327:Coronary Disease / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006321:Heart / Q000503:physiopathology*; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption; D010477:Perfusion; D012039:Regional Blood Flow; D013552:Swine