The potential of disproportionate growth of tricuspid valve after decompression of the right ventricle in patients with pulmonary atresia and intact ventricular septa

Objective: Tricuspid valve size is the major determinant of outcomes for patients with pulmonary atresia with intact ventricular septum. Lack of right ventricle-pulmonary artery continuity is associated with poor tricuspid valve growth (decrement in Z-value). However, most reports did not show evidence for disproportionate growth of the tricuspid valve after establishment of right ventricle-pulmonary artery continuity. Methods: We studied 40 patients with pulmonary atresia with intact ventricular septum who underwent initial right ventricular decompression for planned staged repair. The initial Z-value of the tricuspid valve diameter (Zt1) was obtained from the echocardiography-derived normal value. The late Z-value (Zt2) was measured before definitive repair or the last available Z-value, if definitive repair was not yet reached. The factors associated with the changes of Z-values (Zt2 - Zt1) were analyzed. Results: The mean initial tricuspid Z-value (Zt1) was -6.2 ± 3.5. After treatment (Zt2), the mean Z-value was -6.0 ± 3.4 (n = 34). Overall, the tricuspid Z-values did not change. Individually, the change in Z-value (Zt2 - Zt1) was larger than +2 in 11 (32%) patients and smaller than -2 in 6 (18%) patients. Increases in Z-value (Zt2 - Zt1) were significantly associated with right ventricular pressure/left ventricular pressure ratio measured after initial palliation (r = -0.54; P = .001) and the initial tricuspid valve Z-value (Zt1) (r = -0.40; P = .02). Conclusions: Disproportional growth of the tricuspid valve can occur, especially in patients with small tricuspid valves and lower right ventricular pressures after decompression. The findings support the possibility of neonates with small tricuspid valves undergoing biventricular repair after right ventricular decompression surgery.