Morphologic Features of the Hypoplastic Left Heart Syndrome-A Reappraisal

The report describes the morphologic features of 102 specimens with hypoplasia of the chambers of the left heart, all with either a concordant atrioventricular connection (66 cases) or absence of the left atrioventricular connection, the right atrium being connected to a dominant right ventricle (36 cases). Either the aorta was connected to the left ventricle, having a patent valve in 23 cases and an imperforate valve in 5, or else the aortic trunk was atretic (74 cases). It was not possible to determine with certainty the ventricular origin of the aorta when its trunk was atretic, but in all hearts but 1 it seemed to be connected to the left ventricle. The atrial septum was intact in 11 hearts and grossly restrictive in a further 8. Deviation of the atrial septum relative to the infolded atrial roof (septum secundum) was seen in 32 specimens. The ventricular septum was intact in 88 hearts. The length of the left ventricle compared to the right was greatest in the 14 hearts with a ventricular septal defect. The left ventricular length was also significantly greater in hearts with a patent aortic valve. The state of the atrial septum, in contrast, bore no relationship to the dimensions of the left ventricle. Aortic coarctation was found in 44 of the hearts, and in all but 2 the shelf lesion was preductal in location. Coarctation was significantly more frequent in those hearts in which the ascending aorta was less than 3 mm in diameter. The anatomic findings are discussed in relation to recent advances in the surgical palliation of these malformations.