Anomalies of the Right Ventricular Outflow Tract and Pulmonary Valve

Pulmonary valve stenosis is the fourth most common congenital heart lesion, occurring in approximately 53 per 100, 000 live births. Chronic pulmonary stenosis leads to right ventricular hypertrophy, especially in the outflow tract or infundibulum. Improved right ventricle (RV) function and decreased pulmonary vascular resistance will have minimal effects on the cardiac output in patients with an abnormal valve, the gradient across the valve will increase. Discrete fibromuscular subpulmonary obstruction is described as a ring or fibromuscular diaphragm with an orifice located at the infundibular ostium or within the RV infundibulum. In patients with discrete subpulmonary stenosis, a nonmobile, thick ridge is seen at the level of the proximal infundibular ostium. Echocardiographic assessment starts in many cases as the patient is weaned from cardiopulmonary bypass. Obstruction distal to the pulmonary valve can occur at the level of the main pulmonary artery and/or pulmonary artery branches.