Anomalous coronary arteries are a rare occurrence in which the arteries that supply the heart with blood (the coronary arteries) do not come from the usual location on the large artery that arises from the heart (the aorta) or may have unusual branching patterns. They may occur with or without additional congenital heart disease.
Some types of congenital heart disease (CHD) such as d-transposition of the great arteries or Tetralogy of Fallot have a higher association with anomalous coronary arteries than other forms of CHD.
If the course of one of the major coronary arteries runs between the two major vessels leaving the heart (aorta and pulmonary artery), there is a possibility of pinching of the coronary artery and its flow back to the heart muscle. This may pose increased risk during exercise and strenuous activities. It is also possible for one of the coronary arteries (typically the left) to arise from the lung (pulmonary artery) rather than directly from the aorta. This is referred to as anomalous left coronary artery from the pulmonary artery (ALCAPA). ALCAPA usually presents in infancy, though may be undetected in some until later in life.