Pulmonary stenosis (PS) at the valvar level accounts for 8 to 10 percent of all congenital heart defects. In most patients, the pulmonary valve is found to be dome-shaped, with commissural fusion and variable subvalvar right ventricular outflow tract (RVOT) obstruction. The pulmonary annulus may be normal in size or smaller than predicted, and a patent foramen ovale (PFO) or atrial septal defect (ASD) is usually present. Clinical presentation is variable. Although severe PS may present in the newborn period, most of these lesions do not manifest significant signs and symptoms until later in childhood. Clinical findings are directly related to the severity of the RVOT obstruction and the degree of shunting across the atrial septum. Timing of intervention is based on severity of clinical findings and is indicated when an RVOT gradient exceeds a mean of 50 mm Hg. Although balloon valvotomy has become the initial therapeutic intervention in most patients, surgical valvotomy still remains an important form of intervention in a subset of these patients. Both catheterization with balloon valvotomy and surgical valvotomy are associated with low morbidity and mortality and excellent long-term survival.
Pulmonary atresia (PA) with intact interventricular septum (IVS) is an uncommon defect, representing between 1 and 3 percent of all congenital heart lesions. By definition, there is no communication between the right ventricle (RV) and the pulmonary arteries and no antegrade pulmonary blood flow through the RVOT. Consequently, a patent ductus arteriosus (PDA) is essential for early survival. The defect presents with varying degrees of hypoplasia of the RV and tricuspid valve, and often involves RV-to-coronary artery fistulas (45 percent). In addition, the tricuspid valve may have an Ebstein malformation (10 percent), and a right ventricle-dependent coronary circulation (RVDCC) is found in 10 to 15 percent of patients.
In neonates with PA/IVS, surgical classification of RV hypoplasia into mild (more than two-thirds of normal), moderate (one-third to two-thirds of normal), and severe (less than one-third of normal), as well as accurate assessment of the TV annular diameter, is useful in directing surgical management. A similar classification strategy is used for surgical management in older children. This allows patients to be stratified into those who will most likely achieve a biventricular repair and those who are best suited for a single ventricle pathway.