Hypoplastic left coronary artery. In association with occlusive intimal thickening of a coronary artery with ectopic ostium and with atresia of the left coronary ostium.

Two cases of hypoplastic coronary artery (HCA) are presented. Case 1, a 13 year old girl, died suddenly during a long distance race. She had HLCA with marked intimal thickening and an ectopic left coronary ostium above the commisure between the non-coronary and left coronary cusp at post mortem examination. The right coronary artery (RCA) was enlarged and also supplied parts of the area normally supplied by the left coronary artery (LCA). Pathological findings revealed a normal RCA and an extremely hypoplastic LCA with occlusive proliferation of the intima and a myocardial infarction of the left ventricle. Case 2, a 6 year old girl, had a history of effort angina. Selective coronary angiography was performed which failed to demonstrate the orifice of the LCA by aortography. However, the hypoplastic LCA was visualized by RCA angiography as a consequence of anomalous collaterals from the atrioventricular branch of the RCA. We postulate that HCA results from various conditions, including stenosis of the coronary artery orifice, an aberrant course between the pulmonary artery and aorta and ectopic positioning of the coronary artery ostium. In addition, HCA may also be associated with occlusive coronary artery abnormalities.