Non-atheromatous ischaemic heart disease.

Myocardial ischaemia may result from congenital abnormalities in the origin or distribution of the coronary arteries. Coronary obstruction may also develop at a young age in some rare hereditary disorders such as Hurler's syndrome, homocystinuria or pseudoxanthoma elasticum. The coronary arteries may be the site of embolism; ostial stenosis may complicate luetic (or other) aortitis or coronary dissection; the small coronary arteries may be involved in certain connective tissue disorders such as polyarteritis, in amyloid heart disease or in diabetes. Finally, angina or even infarction may develop in the absence of these disorders and in the demonstrated presence of normal coronary arteries; this not so rare phenomenon has attracted increasing interest now that coronary angiography has become more generally available. Congenital coronary anomalies Anomalous origin ofa coronary artery This is a rare disorder. In its most usual form the left coronary artery arises from the left posterior aspect of the pulmonary artery instead of from the left coronary sinus of the aorta (Fig. 1). The artery then emerges from the pulmonary trunk and the aorta to pursue its usual course. Occasionally the anomalously arising vessel represents only one branch of the left coronary artery, the circumflex or anterior descending then arising normally. Anomalous origin of the right coronary artery has also been described but it is much rarer. Anomalous origin of the left coronary artery results in left ventricular ischaemia or infarction, the extent of this depending on the rate of fall of pulmonary artery pressure after birth and the rapidity