FORCE PATTERNS OF HYPOXIC MYOCARDIUM APPLIED TO OXYGENATED MUSCLE PREPARATIONS - COMPARISON WITH EFFECTS OF REGIONAL ISCHEMIA ON THE CONTRACTION OF NONISCHEMIC MYOCARDIUM

Objective: To examine the basis for local wall motion abnormalities co mmonly seen in patients with ischemic heart disease, computer-controll ed isolated muscle studies were carried out. Methods: Force patterns o f physiologically sequenced contractions (PSCs) from rat left ventricu lar muscle preparations under well-oxygenated conditions and during pe riods of hypoxia and reoxygenation were recorded and stored in a compu ter. Force patterns of hypoxic-reoxygenating and oxygenated myocardium were applied to oxygenated and hypoxic-reoxygenating myocardium, resp ectively. Results: Observed patterns of shortening and lengthening clo sely resemble those obtained from ischemic and non-ischemic myocardial segments using ultrasonic crystals in intact dog hearts during corona ry occlusion and reperfusion, and are similar to findings reported in angiographic studies of humans with coronary artery disease. Conclusio n: The current study, demonstrating motions of oxygenated isolated mus cle preparations which are similar to those in perfused segments of in tact hearts with regional ischemia, supports the concept that the mult iple motions of both ischemic and non-ischemic segments seen in region al myocardial disease can be explained by interactions of strongly and weakly contracting muscle during the physiologic cardiac cycle.