Morphologic determinants of coronary blood flow in the hypoplastic left heart syndrome.

The diameters of the ascending aorta, coronary ostia, and proximal coronary arteries were measured in autopsy specimens from 51 infants with hypoplastic left heart syndrome and 18 normal infant heart specimens. Standard cross sections were prepared from 35 of the hypoplastic left heart syndrome hearts, and histologic indices of myocardial viability and fibrosis were determined. The diameters of the coronary arteries and ostia in hypoplastic left heart syndrome were not different from the values in control specimens. Little fibrosis was found but extensive myocardial necrosis was present. The degree of fibrosis and necrosis did not correlate significantly with any of the arterial or ostial diameters. The extent of myocardial preservation in the hypoplastic left heart syndrome, which may substantially limit the success of surgical palliation, cannot be predicted from these morphologic measurements. The observed myocardial damage appeared to be acquired postnatally, implying that early vigorous treatment of these infants may be necessary to preserve myocardial function.