Anomalous left coronary artery from the pulmonary artery

Anomalous left coronary artery from the pulmonary artery, also known as ALCAPA or Bland-White-Garland syndrome, is a rare congenital heart defect, occurring in about 1 in 300,000 live births, in which the left coronary artery arises abnormally from the pulmonary artery rather than from the aorta. Before birth the defect causes little harm because high pulmonary artery pressure keeps blood flowing to the left coronary artery, but after birth pulmonary pressure drops sharply, so the affected heart muscle comes to depend on collateral blood flow from the right coronary artery, creating an abnormal left-to-right shunt in which blood flows backward from the right coronary artery through the left coronary artery into the pulmonary artery. The defect accounts for between 0.24 and 0.46 percent of all congenital heart disease cases and is a rare but serious diagnosis that can lead to myocardial ischemia and sudden cardiac death without prompt treatment.