Doppler evaluation of homograft valved conduits in children

Abstract

To assess the flow characteristics of homograft valved conduits in the immediate postoperative period, 69 children with 71 homograft conduits underwent 2-dimensional and Doppler echocardiographic examination at 1 to 40 days (mean 8) after surgery. Of the 71 conduits studied, 19 were aortic and 52 were pulmonary homograft valved conduits. Two aortic homograft valved conduits were inserted in the aortic position, whereas all remaining homografts were placed in the pulmonary position. On the immediate postoperative echocardiogram, 25 (35%) of the conduit valves had no regurgitation and 44 (62%) had 1+ (mild) regurgitation. Two pulmonary valved conduits (3%) in the pulmonary position had 2+ (moderate) regurgitation and right ventricular dimensions >95% for body surface area. The peak velocity across the homograft valve was normal (<1.3 m/s) in 58 valves (82%). In the remaining 13 valves, peak velocity ranged from 1.4 to 2.6 m/s. No homograft valve had a peak velocity >2.6 m/s in the immediate postoperative period. To assess the fate of homograft valved conduits in the intermediate-term follow-up period, 38 children with 38 conduits had a repeat echocardiogram at 6 to 25 months (mean 15 ± 6) after surgery. Of the 38 conduits examined, 10 (26%) had no regurgitation, 25 (66%) had 1+ regurgitation and 3 (8%) had 2+ regurgitation. Progression of the amount of regurgitation occurred in 11 (29%) patients. At the follow-up examination, peak velocity was ≤1.4 m/s across 34 conduit valves, between 1.4 and 2.6 m/s across 3 valves and >2.6 m/s across 1 valve. This latter patient had a 3.2-m/s jet across the proximal insertion of the conduit and no further increase across the valve itself. Thus, no patient had evidence of conduit valve stenosis. Of the 38 patients, 9 had Doppler evidence of obstruction at the conduit insertion (8 at the distal end and 1 with the aforementioned proximal obstruction). Most obstructions were of mild to moderate severity and only 2 patients (5%) had severe conduit stenosis. Thus, in the immediate postoperative period, normally functioning homograft valved conduits frequently have mild regurgitation (62%) and rarely have moderate or severe regurgitation (3%), with peak velocities reaching <2.6 m/s. In the inpatients, 9 had Doppler evidence of obstruction at the conduit insertion (8 at the distal end and 1 with the aforementioned proximal obstruction). Most obstructions were of mild to moderate severity and only 2 patients (5%) had severe conduit stenosis. Thus, in the immediate postoperative period, normally functioning homograft valved conduits frequently have mild regurgitation (62%) and rarely have moderate or severe regurgitation (3%), with peak velocities reaching <2.6 m/s. In the intermediate follow-up period, homograft valved conduits may develop an additional degree of regurgitation (29%), frequently continue to have conduit peak velocities <2.6 m/s (97%) and uncommonly develop hemodynamically significant obstruction, usually at the ends of the conduit (5%).