Coronary arteries in the hypoplastic left heart syndrome. Histopathologic and histometrical studies and implications for surgery.

The subepicardial coronary arteries (CAs) in the hypoplastic left heart syndrome (HLHS) were studied for pathology dependent on the patency of the mitral valve and the presence of endocardial fibroelastosis (EFE) of the left ventricle (LV). Nine heart specimens with aortic and mitral atresia (group 1) were studied and compared with 19 hearts with aortic atresia and mitral stenosis (group 2) (EFE of the LV was present in all cases) and 10 normal hearts. The median age at death was 3 days. For the histological and histometrical studies, 5-mm blocks from six comparable sites of the left (L) and right (R) CAs were serially sectioned and routinely processed. The arterial size and wall thickness were measured. Macroscopically, the CAs in group 1 were normal except for the prevalence of left dominance (56%). In contrast in group 2, the CAs were thicker and tortuous. Histopathology was restricted almost exclusively to group 2 specimens (11 of 19), with the proximal LCAs being the most affected. However, eight hearts with EFE in group 2 had no structural wall changes of the CAs. Histometrically, the sizes (external diameters) of the LCAs and RCAs were similar (0.5-1.0 mm) in groups 1 and 2 and in the normal group; however, we noted an increase in percent medial thickness in group 2 specimens, especially of the LCAs. Furthermore, in some group 2 hearts, the wall thickness (intima and media) relative to the luminal size (internal radius) of proximal and middle LCAs was significantly increased, suggesting the presence of ventricle-CA communications.(ABSTRACT TRUNCATED AT 250 WORDS)