Twin-twin transfusion syndrome: the influence of intrauterine laser photocoagulation on arterial distensibility in childhood.

BACKGROUND In twin-twin transfusion syndrome (TTTS), the donor and recipient fetus are exposed to differing volume loads and show discordant intertwin vascular compliance in childhood despite identical genotype. We hypothesized that discordance is prevented by intrauterine endoscopic laser ablation of placental anastomoses, which abolishes intertwin transfusion. We tested this by examining pulse wave velocity (PWV) in brachial arteries of twin survivors of TTTS treated with and without laser therapy. METHODS AND RESULTS One hundred children (50 twin pairs, 27 with TTTS) were studied. Group 1 comprised 14 monochorionic (MC) twin pairs with TTTS treated symptomatically; group 2 comprised 13 MC twin pairs with TTTS treated by laser. The control groups comprised 12 MC twin pairs without TTTS (group 3) and 11 dichorionic twin pairs (group 4). Fetal cardiovascular data, predictive factors for, and duration of TTTS and cord blood were collected prospectively. We measured blood pressure and PWV photoplethysmographically at a median corrected postnatal age of 11 months (range, 1 week to 66 months). Both TTTS groups showed marked intertwin PWV discordance, unlike MCDA control subjects. The PWV discordance seen in laser treated twin pairs resembled that of dichorionic control subjects (heavier individual with higher PWV), whereas group 1 showed the opposite (negative) intertwin discordance (ANOVA F (1,45)=4.5, P=0.04). No significant differences in blood pressure or intrauterine growth were observed between TTTS groups. CONCLUSIONS Vascular programming is evident in monozygotic twins with intertwin transfusion and is altered but not abolished by intrauterine therapy to resemble that seen in dichorionic twins.