title: Effect of graded coronary flow reduction on ionic, electrical, and mechanical indexes of ischemia in the pig.
abstract: This study was performed to determine the relative sensitivities of ionic, electrical, and mechanical indexes of myocardial ischemia. We used ion-selective and bipolar plunge electrodes, epicardial unipolar electrodes, a suction electrode, and ultrasonic crystals to determine the changes in intramyocardial extracellular potassium ([K+]e) and extracellular pH (pHe), local activation, epicardial TQ-ST segment, monophasic action potential duration (MAPD), and regional contractility during graded coronary flow reduction in open-chest pigs. A carotid-to-coronary shunt was created to perfuse the left anterior descending coronary artery via a roller pump. The shunted coronary flow was reduced in a stepwise fashion at 5-min intervals. In 25 pigs, the approximate myocardial blood flow associated with the initial changes in each variable was as follows: midmyocardial [K+]e, pHe, and TQ-ST segment, 0.7 to 0.8 ml/min/g; subepicardial [K+]e and TQ-ST segment, 0.6 to 0.7 ml/min/g; segmental shortening, 0.5 to 0.6 ml/min/g; local activation and epicardial TQ-ST segment, 0.3 to 0.4 ml/min/g; epicardial MAPD, 0.15 to 0.2 ml/min/g. Our results indicate that changes in [K+]e, pHe, and TQ-ST segment provide the most sensitive means of detecting myocardial ischemia and of determining the effect of interventions capable of influencing the ischemic process.
authors: Department of Medicine, University of North Carolina at Chapel Hill 27514.
authors: I
authors: I
authors: Watanabe
authors: T A
authors: TA
authors: Johnson
authors: J
authors: J
authors: Buchanan
authors: C L
authors: CL
authors: Engle
authors: L S
authors: LS
authors: Gettes
mesh_terms: D000200:Action Potentials; D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D003327:Coronary Disease / Q000378:metabolism / Q000503:physiopathology*; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology; D006863:Hydrogen-Ion Concentration; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D010496:Pericardium / Q000503:physiopathology; D011188:Potassium / Q000378:metabolism; D013552:Swine
chemical_list: D011188:Potassium