title: The quantitative effects of coronary-myocardial ischemia on the S-Q integrals of epicardial electrograms in the dog.
abstract: The purpose of this study was to measure the relationship between quantitative changes in an epicardial electrocardiographic complex and times of total occlusion and reactive hyperemia in the coronary vessel that supplied the myocardium beneath the electrode. Fifty-six experiments were performed on 9 open-chest dog preparations in which the left anterior descending coronary artery had been cannulated and connected by tubing to the left carotid artery. The shunt was totally occulded for 5, 10, 30, 60 and 90 sec intervals and the sugsequent reactive hyperemia was recorded with an extracorporeal electromagnetic flowmeter placed in the shunt. Potentials from an epicardial electrode placed over the probable area of perfusion of the artery were recorded and analyzed by a digital computer. The integral of each beat from the S to the Q point of the ECG complex was computed. The total electrophysiological change from baseline thus quantified was found to be linearly correlated with the volume of flow deprivation during occlusion (perfusion volume debt) and the volume of reactive hyperemic repayment. The study substantiates experimentally earlier exercise studies of patients with ischemic heart disease in which changes in the SQ integral were found to correlate linearly with exercise intensity. The results support the hypothesis that quantitative measures of the electrocardiographic complex may be used to document the severity of ischemia in mammalian ventricles.
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization; D003327:Coronary Disease / Q000503:physiopathology*; D004285:Dogs; D004562:Electrocardiography; D004594:Electrophysiology; D006493:Heparin / Q000008:administration & dosage; D006940:Hyperemia / Q000503:physiopathology; D009203:Myocardial Infarction / Q000503:physiopathology; D010477:Perfusion; D013223:Statistics as Topic; D013903:Thoracic Surgery; D013909:Thorax / Q000601:surgery; D013997:Time Factors
chemical_list: D006493:Heparin