Hibernating myocardium

Abstract

In 1973 Chatterjee and colleagues, on the basis of clinical observations, suggested that a “marked improvement and even normalisation of left ventricular function can be expected in properly selected patients with the preinfarction syndrome or with chronic ischaemia and no previous infarct, following appropriate aortocoronary artery bypass surgery”.1 Five years later Diamond and associates were the first to use the word “hibernation” in the introduction to an experimental study on postextrasystolic potentiation in ischaemic dog myocardium.2 Somewhat vaguely, they concluded from the “sometimes dramatic improvement in segmental left ventricular function following coronary bypass surgery” that “ischaemic non-infarcted myocardium can exist in a state of function hibernation.” In the early 1980s, Rahimtoola systematically reviewed the results of coronary bypass surgery trials and identified patients with coronary artery disease in whom chronic left ventricular dysfunction improved on revascularisation.3 4 He then specified the term “hibernation” previously used by Diamond and associates, and proposed that the observed contractile dysfunction was not the result of an ongoing energetic deficit but an adaptive downregulation of contractile function to preserve myocardial integrity and viability.4 Thus the concept of myocardial hibernation challenged the traditional view of myocardial ischaemia which assumed that the extent of chronic contractile dysfunction reflected the amount of infarcted tissue. This new pathophysiological concept of hibernating myocardium was further popularised by Braunwald and Rutherford,5 who emphasised the need for its recognition and treatment through revascularisation. When proposing the concept of hibernation, Rahimtoola reasonably assumed that the observed reduction of contractile function reflected a situation of reduced resting blood flow.4 Experimental studies indeed showed a proportionate reduction in regional myocardial blood flow and contractile function in response to graded reductions in coronary flow in dog hearts during acute6 and subacute ischaemia,7 as well as in pig hearts …