MIOCÁRDIO DISFUNCIONAL "HIBERNANTE"

MIOCÁRDIO DISFUNCIONAL "HIBERNANTE": ESTUDO POR MICROSCOPIA ÓPTICA E ELETRÔNICA

XX Congresso da Sociedade Brasileira de Microscopia e Microanálise /

I Simpósio Brasileiro de Microscopia Aplicada às Ciências Forenses, 2005,

Águas de Lindóia, SP, Brasil

SUMMARY:

The recognition of hibernating myocardium is possible by the stimulants of inotropic reserve as the dobutamine stress echocardiography (DSE).This study analyses morphological aspects of dysfunctional myocardium detected by DSE, through the conventional light  (LM) and electron microscopy (EM).Thirteen patients, age range 50-79 years, with severe coronary artery disease were submitted to myocardial biopsy during revascularization. Transmural biopsies were obtained from dysfunctional areas detected at resting echocardiography and with improvement of wall motion with DSE - ischemic areas, and from region with normal wall motion at resting and DSE - “control areas”. Normal cardiac myocytes were observed in all biopsy samples related to cells with cytological abnormalities, frequently in areas with wall motion alterations. LM showed muscle cells with variable nuclear and cytoplasmic volumes, contracted and irregular bands and loss of contractile material replaced by glycogen and intercellular fibrosis. EM showed contracted and irregular bands, depletion of contractile material with replacement by glycogen and small mitochondria, tortuous nuclear contour and variable amounts of collagen in the intersticialspace.The abnormalities in the contractile material, glycogen deposits and modified  mitochondria and nucleus contour are considered as hallmark of hibernating myocardium, and might represent a structural adaptation to long-term hypoperfusion.This characterization is only possible with recovery of the normal wall motion after revascularization. Morphological alterations in areas with normal response to the DSE might be represent a localized wall motion impairment no large enough to be detected or the normal cells would compensate the abnormal cells function.pdf.