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OC07.04: Pattern of cardiovascular disease regression following fetoscopic selective laser photocoagulation (SLP) for twin–twin transfusion syndrome (TTTS)

Objectives: Fetoscopic SLP improves outcome in TTTS by promoting resolution of cardiovascular (CV) manifestations. The time course and pattern of disease regression is unknown. We sought to investigate the nature of CV disease regression after SLP by analysis of individual cardiovascular elements through application of the CHOP score for TTTS. Methods: The CHOP score is a fetal echo derived system for detailed CV characterization of TTTS. Elements of the Score include 4 domains in the recipient: 1) ventricular characteristics of dilation, hypertrophy, systolic dysfunction, 2) atrioventricular valve (AV) regurgitation, 3) diastolic properties of Doppler AV inflow (double or single peak), ductus venosus, and umbilical venous flow, 4) right ventricular outflow tract obstruction (RVOTO) as assessed by pulmonary artery measuring smaller than aorta or pulmonary stenosis/atresia; and in the donor, evaluation of umbilical artery diastolic flow. In 32 twin pairs individual elements of the Score as well as myocardial performance indices (MPI) were measured at 1 day and 1 week after SLP and compared to pre-op values using paired t-test. Results: Overall score was unchanged at 1 day (pre-op 6.6 + 4.0 vs. 6.0 + 3.8, P = NS) but significantly improved by 1 week (4.2 + 4.1, P < 0.001) after SLP. At 1 day, there was no improvement in systolic or diastolic parameters and AV regurgitation worsened, however there was slight improvement in RVOTO (P < 0.05) and recipient RV and LV MPI (P = 0.02). At 1 week, improvements in ventricular dilation (P = 0.01), hypertrophy (P = 0.01) and all of the diastolic parameters were noted, with further improvement in RVOTO (P = 0.002) and recipient RV and LV MPI (P < 0.01). Systolic performance and AV regurgitation did not improve. Conclusions: Minimal improvement is seen 1 day after SLP, however diastolic CV elements, but not systolic, improve substantially at 1 week. Acute diastolic relaxation of the recipient right ventricle after SLP may improve filling and result in an increase in pulmonary artery diameter.