Pulmonic regurgitation and reconstruction of right ventricular outflow tract with patch. An experimental study

Twenty-five dogs were divided into three experimental groups. In each animal of Group I (10 dogs), one pulmonary valve leaflet was resected and a monocusp-bearing bovine pericardial patch was sewn into the right ventricular outflow tract. The monocusp was retracted to the patch with plicating sutures, and when the sutures were removed the monocusp became functional. In each animal of Group II (10 dogs), an incision was made in the right ventricular outflow tract along the anterior pulmonary valvular commissure and a bovine pericardial patch of adjustable width (one half, one, or one and one half times the diameter of the pulmonary valve ring) was sewn into the incision. Group III (five dogs) was the control group. During each situation of altered pulmonary valve function, in each experimental animal, the pulmonary blood flow and intracardiac pressures were measured. Pulmonary regurgitation was expressed regurgitant fraction (retrograde flow divided by net forward flow). We reached the following conclusions: In all situations where pulmonary incompetence was created, the regurgitant fraction was related directly to the width of the patch and was usually not more than half of the net forward flow when the width of the patch was less than one and a half times the pulmonary valve ring diameter. Regurgitant fraction was about half of net forward flow when one leaflet had been excised. The index of pulmonary artery diastolic pressure minus right ventricular end-diastolic pressure was sensitive and bore an inverse relationship to the degree of pulmonary regurgitation. An accurately placed monocusp-bearing patch restored pulmonary valve competence after excision of a cusp. In treating patients, we are encouraged to preserve as much pulmonary valve function as possible.