Background : To determine the relative role of pulmonary insufficiency and right ventricular (RV)outflow tract damage in the genesis of the late symptoms related to RV dilatation, we compared the late outcome of patients who had undergone operations known to generate pulmonary insufficiency : transventricular repair of tetralogy of Fallot and isolated pulmonary commissurotomy.
Methods and Results : In our institution, between 1964 and 1984, 44 pts had an isolated pulmonary commissurotomy and 189 survived a transventricular repair of tetralogy of Fallot : 134 had a patching of the RV and 55 a direct closure of a right ventriculotomy. Follow-up was 94 % complete after a mean of 22 ± 7 years. Echocardiography was obtained in 125 of the 182 survivors who had not undergone a reoperation for RV dilatation. Pts with isolated commissurotomy and tetralogy of Fallot had similar proportion of moderate (38% vs 43%, p=0.66 )and severe pulmonary insufficiency (23% vs 29%,p=0.52). Cardiac death, reoperation for symptoms due to RV dilatation, and NYHA class < 2 were investigated as adverse events related to RV dilatation. Among the pts who had a pulmonary commissurotomy, there were no cardiac death or reoperation. The freedom from all these adverse events was better for pts with a commissurotomy than for pts with a direct closure of the RV (log rank p = 0.02) or a RV patch (log rank p< 0.001)(fig). In pts with an isolated commissurotomy, the ratio between end-diastolic right and left ventricular dimensions was smaller than in pts with a RV patch (0.56 ± 0.14 vs 0.71 ± 0.24, p<0.001) and similar to the ratio of the pts with direct closure of a right ventriculotomy (0.60 ± 0.17,p=0.33).
Conclusion : Pulmonary insufficiency may not be the key factor leading to symptomatic RV dilatation in pts operated of tetralogy of Fallot. Long-term pulmonary insufficiency alone is responsible for slight degree of RV dilatation but provided that the pts have normal pulmonary arteries, symptoms may never develop if the contractility of the pulmonary infundibulum is preserved.