Models and problems in the study of myocardial ischemia and tissue protection

Myocardial protection and the control of ischemic injury has been highly successful clinically in the field of cardiac surgery where hearts are made globally ischemic. By contrast, protection of the regionally ischemic myocardium, as found during evolving myocardial infarction, has been less successful and, despite numerous experimental and clinical studies, very controversial. Confusion over the feasibility of infarct size reduction can be attributed to a number of factors including: (1) uncertainty over the nature of the interface between normal and ischemic tissue (the 'border zone controversy'), (2) the inadequacy of many indices of tissue injury and protection. (3) the failure of most studies to make the critical distinction between delaying and reducing injury, (4) the adequacy or inadequacy of many experimental models of human ischemia. In this article some of these problems are reviewed and advantages and disadvantages of a variety of experimental models considered.