Resumen

BERMUDEZ ARIAS, Fernando. La recuperación del miocardio hibernado mejora el pronóstico de la cardiopatía isquémica metabólica. Gac Méd Caracas [online]. 2005, vol.113, n.1, pp.19-41. ISSN 0367-4762.

The physiopathologycal mechanisms of both stunning and hibernating myocardium and the connections between them have recently been the objet of multiple revisions. Stunning is the contractil disfuntion of transitory character and variable duration (minutes to weeks), as consecuense of an acute or subacute ischemia period. Nevertheless, is of limited importance because there is a good response to the inotropic stimulation and it is progressively solved in a spontaneous manner. Their physiopathological mechanisms are not known and it is still debated whether it is fundamentally an ischemical sequel damage or a reperfusion undesirable collateral effect. This is especially true in the reperfusion initial phase when a fast oxygen free radicals increase takes place (either by coronary bypass surgery or by percutaneous transluminal coronary angioplasty). This does not occur when it is slowly done (pharmacologic revascularization). Stunning and hibernating myocardium is defined as persistently impaired myocardial and left ventricular function at rest, resulting from reduced myocardial blood flow. It is postulated that despite the reduced coronary blood flow, metabolic activity is sufficient to prevent tissue necrosis. The hibernating myocardial definition is controverted, as the heart chronic disfunction in not well known because the it is coronary artery disease dependent. The heart hibernating response namely a cardiac function reduction to cope with a reduced myocardial blood flow, has been considered a self preservation act (little blood, little work) for which the hibernating heart is thought of "a smart heart". It have been show that a coronary flow severe decrease can give rise to an adaptive contractile activity and other heart functions reduction, within hours, days, months or years of duraction, without cellular death, but with adenosintriphosphate maintenance levels. In some cases of chronic hibernation, the coronary flow can be normal at the rest, suggesting that this situation could be explained by itself as repetitive and predominantly ischemia-stunning-hibernating silent episodes. Also, collateral circulation development takes palce, dependent on the ischemic preconditioning myocardium. This is defined as the tolerance increase to prolonged isquemia provided by one or more short of isquemia cycles followed by reperfution. The thrombus stability by fibrosis wich avoids its disintegration possibility, the myocardial metabolic state, the inflammatory process degree (determined by the polimorphonuclears presence) the previous necrotic area extention and the necrotic and fibrous myocardium predominance over the hibernating one, make more difficult the hibernating myocardium recovery towards normality. The hibernating myocardium differentiation from nonviable myocardium in patients with coronary artery disease and left ventricular dysfunction is a key issue in the current myocardial revascularization. In this 12 years long clinical investigation of 7 049 cases with acute, subacute and chronic metabolic heart disease, neither with selective inclusion nor exclusion of cases, we showed than there was hibernating myocardium in all of them, which was recovered (asyntomatic) with pharmacological-dietetic-causal treatment with near-normal electrocardiogram, recovered in a proportion around 90 % to 95 %.