Pulmonary vein drain into the pulmonary circulation in whole or in part, this is known as a total anomalous pulmonary venous connection (or drainage), or partial anomalous pulmonary connection, respectively. Pulmonary vein The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four "main pulmonary veins", two from each lung that drain into the left atrium of the heart. The pulmonary veins are part of the pulmonary circulation. Two main pulmonary veins emerge from each lung hilum, receiving blood from three or four bronchial veins apiece and draining into the
Major aortopulmonary collateral artery with congenital heart diseases with decreased pulmonary blood flow like tetralogy of Fallot or pulmonary atresia it may be seen sometimes in isolation i.e. not associated with any congenital heart disease in that case it is termed as isolated aortopulmonary collateral artery. In these cases it may be one of the cause of congestive cardiac failure in neonates. Pulmonary arteries come from the right side of the heart, and usually carry deoxygenated blood from the body. These collateral arteries carry blood which has already been oxygenated by the lungs, so are of little use in helping the body to get