Growth and function of hypoplastic right ventricles and tricuspid valves in infants with pulmonary atresia and intact ventricular septum

The pulmonary atresia and intact ventricular septum (PAIVS) spectrum usually includes very hypoplastic right ventricles (RVs) and tricuspid valves (TVs) and often RV-coronary artery connections (RV-CACs). These abnormalities are often thought irreversible and typically only 30% reach a 2-ventricle repair (2VR). Our hypothesis, however, has been PAIVS is a developmental defect and catch-up growth is possible in all. To answer this question, we attempted to obtain up to 10. year echo data on RV and TV growth and function in the 24 survivors (of 28 patients) from 1989 to 1999. To maximize the validity of the growth results obtained, we used only paired studies and required biplane echos to accurately estimate RV volumes, TV size, and function. Measurements were indexed to determine the z score (standard deviation of the mean from predicted).All patients had an RV outflow patch and ASD reduction. We have found catch-up growth required complete relief of RV obstruction and a mildly restrictive (3-5. mm. Hg) ASD to encourage TV flow. A central shunt was placed in 38%. RV-CACs (2.7±1.6/pt) were uneventfully ligated off bypass in 9/28 (32%). For the 24 survivors, 19 adequate paired biplane studies were obtained from here and elsewhere and for 12 allowed a 10. year follow-up.The RV volume z scores grew from - 5.1±2.5 to 0.9±1.9 about 10. years later. The TVs, even with increased flow early, grew more slowly than the RVs. Nevertheless, the very small TVs in 10 pts went from z scores of - 4.6±0.4 to - 0.04±- 1.5 within about 5-10. years. Valvotomies were done in 3. RV function was high normal (EF=74.5±0.1%) presumably because of pulmonary regurgitation in the 8 pts who had adequate studies.We conclude: (1) Catch-up growth appears reliable in PAIVS pts when RV obstruction is relieved and TV flow is increased (2) RV function was good and resembled well-repaired TOF (3) These results encourage pursuing 2VRs in PAIVS patients.