Transmural progression of morphologic changes during ischemic contracture and reperfusion in the normal and hypertrophied rat heart.

The purpose of this study was to compare the functional and morphologic changes that occur during ischemic contracture and reperfusion in the normal and hypertrophied heart. Hearts from Sprague-Dawley, spontaneously hypertensive (SHR), and normotensive Wistar-Kyoto rats were evaluated using a modified Langendorff perfusion apparatus. After obtaining control data, hearts were potassium-arrested, made ischemic, and studied at various time points. Regional coronary flow was assessed with the use of radiolabeled microspheres or Microfil dye infusion, and morphologic changes were evaluated by means of light and electron microscopy. Sarcomere length changes and qualitative morphologic changes during global ischemia demonstrate a transmural progression of ischemic damage starting at the endocardium and extending, with time, epicardially. The progression of ischemic changes in hypertrophied hearts of SHRs was similar to that of normal hearts; however, hypertrophied hearts developed ischemic contracture sooner than normal hearts. In addition, the development of contraction band change after ischemic contracture occurred only when hearts were reperfused and was related to the development of no-reflow.