ABSTRACT
I. THE POSTINFARCTION VIABLE MYOCARDIUM In the course of acute myocardial infarction (AMI), the presence of regional contractile dysfunction of the left ventricle is not always an index of myocardial necrosis. In fact the finding of a dyssynergic area of myocardium can also indicate an area of “dysfunctioning, but still viable” myocardium. The definition of “viable myocardium” is applied to two different pathophysiologic conditions:
(a) the “stunned myocardium” that characterizes a postischemic dysfunctional myocardium in the presence of normal regional blood flow (Fig. 1A) (1);
(b) the “hibernating myocardium”, characterized by reversible loss of contractility in the presence of reduced blood flow in comparison to normal regional values (Fig. 1B); in this condition, the myocardium reacts with downregulation of the contractile activity to the reduction of flow to reduce the myocardial oxygen consumption at most (“smart heart”) (2).
