Absence of the pulmonary valve: Report of two cases associated with other congenital lesions

Two case reports of congenital absence of the pulmonary valve are presented. In one, associated ventricular septal defect, overriding aorta and an infundibular pulmonary stenosis were observed. In the other, aneurysm of the left aortic sinus and a dilatation of both coronary sinuses of Valsalva were found in addition to a ventricular septal defect, over-riding aorta and an orificial pulmonary stenosis. Thirteen other instances of this anomaly have been previously reported and it was most frequently associated with a ventricular septal defect and pulmonary stenosis (tetralogy of Fallot). This anomaly is accompanied by clinical signs of organic pulmonary valve insufficiency. The combination of absence of the pulmonary valve with the malformations of the tetralogy of Fallot is believed to result in a distinct clinical syndrome, manifested by cyanosis, systolic and diastolic murmurs, aneurysmal pulmonary artery, a right ventricular-pulmonary arterial pressure gradient, and a bidirectional shunt at the ventricular level. It is suggested that the combination of absence of the pulmonary cusps and abnormally large aortic cusps favors the hypothesis of an unequal division of the truncus arteriosus as the embryologic error responsible for the reduction of pulmonary cusps in some cases.