Absent pulmonary valve syndrome

Absent pulmonary valve syndrome (also called congenital absence of the pulmonary valve) is a congenital heart defect that occurs when the flaps of the pulmonary valve do not develop or are severely underdeveloped (hypoplasia) resulting in aneurysms (dilation) of the pulmonary arteries and softening of the the trachea and bronchi (tracheobronchomalacia). Usually, APVS occurs together with other congenital heart defects, most commonly ventricular septal defect and right ventricular outflow tract obstruction. It is sometimes considered a variant of Tetralogy of Fallot.