Right ventricular outflow tract obstruction after arterial switch operation for the Taussig–Bing heart☆

Abstract

Incidence of right ventricular outflow tract obstruction (RVOTO) may be suspected to be higher after arterial switch operation (ASO) for Taussig-Bing heart than after ASO for transposition of the great arteries (TGA), as Taussig-Bing anomaly is frequently associated with aortic arch obstruction and subvalvular aortic stenosis. We evaluated the risk to develop RVOTO after ASO for Taussig-Bing heart. The 34 Taussig-Bing cases who underwent ASO from 1984 to 2005 were reviewed. RVOTO was defined as peak echo-gradient >or=30 mmHg across right ventricular outflow tract. Kaplan-Meier method was used to estimate time-related events. Subaortic stenosis was resected in 25 patients, 20 of whom (80%: 20/25) were discharged from hospital free from RVOTO. There was one early death: 2.9% mortality. Three patients died late. Actuarial survival was 85.1%+/-7.0% from 54 month onwards. Eleven survivors (36.7%: 11/30) experienced postoperative RVOTO. Obstruction was seen in 82% (9/11) of cases at subvalvular and/or valvular level. Surgery (n=4) or percutaneous intervention (n=2) was required in six patients. Patients discharged from hospital with RVOTO (n=8) were more likely to undergo reintervention for RVOTO (p=0.026). Freedom from reintervention for RVOTO decreased rapidly in the first two years to 86.5+/-6.3%, slowly thereafter (80.4+/-8.4% at year 7) and stabilized at 70.3+/-11.9% from year 11 on. Risk for RVOTO occurrence was 23.5+/-7.3% early after repair and progressively increased to level out at 53.6+/-11% at year 11. Patients who underwent subaortic resection were more likely (p=0.023) to be free from RVOTO occurrence or development. In the period under review, for patients who underwent ASO for simple (n=355) and complex (n=92) TGA, reoperation rate for neopulmonary stenosis was 0.3% (1/355) and 5.4% (5/92), respectively, to be compared to 11.8% (4/34) RVOTO rate of reoperation for Taussig-Bing heart in this study. Postoperative right-sided obstruction occurs more frequently after ASO repair of Taussig-Bing heart than after TGA arterial switching, leading to higher reintervention rate. Resection of the commonly associated subaortic stenosis often prevents RVOTO development.