Morphology of the patent arterial duct: features relevant to treatment.

Patent ductus arteriosus (PDA), one of the most common congenital heart defects, is an abnormal persistence of a patent lumen in the arterial duct due to an arrest of the natural process of closure after it has served its function as a vital channel in fetal circulation. The histological feature of the arterial duct is entirely different from its adjoining arteries and many intrinsic substances mediate in the process of its normal closure. When existing in isolation, catheter or surgical intervention is usually used for its treatment. Ductal aneurysm is a rare type of PDA. The PDA associated with other congenital heart disease has variable morphology and closing it naturally or by intervention may produce critical symptoms. The PDA and its ligament which represents a closed arterial duct can be part of a vascular ring with abnormal aortic arch formation. It is important to understand the morphological features of PDA so as to choose the optimal strategy for treatment.