VII. OTHER CONGENITAL ANOMALIES
A. Coronary Artery Anomalies in Adults
Anomalies are found in less than —1% of patients undergoing coronary angiography and in less than 0.3% of autopsies. Most of these are, however, benign. Anomalies can originate from the coronary artery from the contralateral coronary sinus. The left main and right coronary artery may arise from the left aortic sinus and cause about 8% of serious coronary anomalies. (See coronary ostia in Figures 5 and 9 in the chapter entitled Anatomy of the Heart and Circulation.) This anomaly is associated with sudden death. Some of these individuals are asymptomatic until they exercise. Another type of anomaly may originate from a single coronary artery or a coronary artery from the pulmonary artery.
1. Clinical Features
Angina, transient loss of consciousness, syncope, myocar¬dial infarction, heart failure, and sudden death may occur with coronary artery anomalies. Sudden cardiac death in young individuals, particularly athletes, has drawn atten¬tion to these anomalies which account for about 15% of these catastrophic events in young adults. Sudden death is more common when the anomalous artery is dominant and supplies a larger part of the heart muscle.
Common causes of sudden cardiac death in young adults include hypertrophic cardiomyopathy (see the chapter Athletes and Sudden Cardiac Death), Brugada syndrome (see the chapter Brugada Syndrome), and coronary artery anomalies. Usually these defects cause symptoms because of a steal phenomenon — areas of heart muscle deprived of blood with oxygen and nutrients. Chest pain, angina, myocardial infarction, shortness of breath, and syncope may occur. Anomalous origin of the left main coronary artery from the right coronary sinus is more frequently symptomatic than when the right coronary artery arises from the left coronary sinus. The origin of the left main coronary artery from the pulmonary trunk is a serious condition that usually causes death during early childhood. The ECG shows broad, deep Q waves in leads I, aVL, V5, and V6, and signs of ischemia. Deep Q waves in lead I are rarely seen except in hypertrophic cardiomyopathy. Survival may occur to puberty in a few cases if myocardial collaterals develop from the normally arising right coronary artery. Apart from the ominous electrocardiographic findings that should lead to immediate investigations, auscultation with the stethoscope may reveal a continuous murmur that serves to differentiate the rare condition from all other cardiac abnormalities. Only a patent ductus arteriosus causes a continuous murmur that is usually very loud and machinery-like. These individuals usually present with syncope, undue shortness of breath, angina, myocardial infarction, or sudden death.