Demonstration of early ischemic injury in porcine right ventricular myocardium.

Past studies of acute canine right ventricular (RV) ischemia have failed to demonstrate early irreversible injury or decreased function; however, the dog has extensive collateral circulation that may attenuate RV myocardial injury. The aim of this study was to measure RV function using contrast ventriculography and assess myocardial injury by immunohistochemical evaluation of creatine kinase (CK), lactate dehydrogenase (LDH), and tropomyosin (TROP) as well as by electron microscopy after right coronary occlusion in 14 closed-chest pigs. Significant depression in RV ejection fraction and stroke volume index after 10 minutes and was observed (P less than 0.05). CK, LDH, and TROP were positive in control tissue with a diminution of CK and LDH staining along the subendocardium after 15 minutes of ischemia. Irreversible ultrastructural injury in conjunction with large losses of CK and LDH became evident after 30 minutes. Thus, in the pig, which has a coronary anatomy similar to humans, significant RV dysfunction and irreversible myocardial injury can be demonstrated after 15 to 30 minutes of ischemia.