A 1-year-old girl with dyspnea and poor feeding is found to be in congestive heart failure. Echocardiography shows an atrio-ventricular septal defect (AVSD). The following is/are true:

a. The second heart sound will show fixed splitting

b. Despite diagnostic echocardiography, cardiac catheterization is indicated to assess pulmonary artery resistance

d. AVSD is classified according to the morphology of the anterior leaflet of the common A-V valve

 AVSD is a defect of endocardial cushion development which produces morphologic abnormalities of both AV valves and both atrial and ventricular septa. It is usually classified according to the morphology of the anterior leaflet of the AV valve. The pulmonary vascular resistance remains elevated in infancy delaying diagnosis and producing fixed splitting of the second heart sound. Cardiac catheterization is indicated to assess pulmonary vascular resistance, but pulmonary artery banding is no longer performed to protect the pulmonary bed. Instead, operative repair is made, preferably before the age of 6 months.