ALCAPA SYNDROME - AN EXAMPLE OF CHRONIC MYOCARDIAL HYPOPERFUSION

Objectives. The purpose of this study was to evaluate functional variables and morphologic correlates of chronically hypoperfused myocardium before and after revascularization. Background. Neonates with congenital anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA syndrome) develop some myocardial necrosis shortly after birth. The survivors of this event are left with a localized infarction and an almost entirely collateral circulation-dependent perfusion of the left ventricle that results in poor global left ventricular function. Survival beyond infancy is uncommon because of severe left heart failure. Revascularization, however, brings about functional recovery with good clinical outcome. The ALCAPA syndrome is thus characterized by chronic collateral circulation-dependent low perfusion, low contraction matching and potential revivability. Methods. Five patients with ALCAPA syndrome are presented, with preoperative and postoperative clinical findings and histologic data obtained from intraoperative transmural biopsy specimens. Results. The angiographically assessed preoperative ejection fraction was 33 +/- 19% (mean +/- SD). Postoperative echocardiographic follow up revealed normal left ventricular function in all patients. Histologic study of the biopsy specimens taken from the region perfused by the anomalous artery showed a variable degree of fibrosis (51 +/- 32%). The ultrastructure of the remaining myocytes revealed viable characteristics, but a substantial percent (46 +/- 26%) showed a markedly reduced fraction of contractile material. Conclusions. These ultrastructural studies suggest delayed subcellular adaptive responses in the chronically hypoperfused myocardium of patients with ALCAPA syndrome.