title: Postsystolic shortening as an index of regional myocardial ischemia in an experimental model.
abstract: 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).
authors.affiliation: Department of Anesthesiology, University of Stellenbosch Medical School, Tygerberg, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Coetzee
authors.forename: P
authors.initials: P
authors.lastname: Fourie
mesh_terms: 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*