Postsystolic shortening as an index of regional myocardial ischemia in an experimental model.
This study explored the relationship between regional myocardial postsystolic shortening (PSS) and myocardial tissue oxygenation in an open-chested animal model subjected to halothane anesthesia. Regional function was examined with reference to the ventricular pressure-length loop and tissue oxygenation gauged from regional arterial-venous lactate dynamics. Coronary blood flow was decreased in steps by application of an external constriction to the left anterior descending coronary artery. Results indicate that a significant change in PSS (from 7.46% +/- 2.14%, mean +/- SEM to 17.74% +/- 3.31%; P less than 0.00001) was associated with a reduction in coronary blood flow from 81.48 +/- 8.85 to 56.94 +/- 7.12 mL/min/100 g tissue (P less than 0.0012), but lactate extraction across the myocardium did not change (10.54% +/- 3.20% to 12.17% +/- 2.43%). A further reduction in coronary blood flow to 39.84 +/- 5.63 mL/min/100 g resulted in severe PSS (50.62% +/- 6.14%) and lactate production (183.81% +/- 28.80%). The correlation between PSS and lactate production was significant (r = 0.873; SEE = 50.49; P = 0.000001).
Coetzee
A
A
Department of Anesthesiology, University of Stellenbosch Medical School, Tygerberg, South Africa.
Fourie
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P
D000818:Animals; D003326:Coronary Circulation / Q000502:physiology; D003327:Coronary Disease / Q000503:physiopathology*; D009200:Myocardial Contraction / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D013552:Swine; D013599:Systole / Q000502:physiology*