Fetal haemodynamics in monochorionic twin

Aim: To understand myocardial performance index (MPI)-conventional Doppler, MPI'-tissue Doppler imaging (MPI'-TDI) and aorthic isthmus pulsatility index (AoI PI) normal trend in uncomplicated monochorionic diamniotic pregnancies, and to study the impact of fetal cardiac function on outcome of monochorionic (MC) twin pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) in order to improve identification of cases and indications for therapy. Materials and Methods: MC twin pregnancies examined between January 2009 and December 2012 at the University Hospital Spedali Civili of Brescia. 84 uncomplicated pregnancies (Group 1; controls) were studied and compared to 46 complicated pregnancies: 34 TTTS (Group 2), 10 selective intrauterine growth restriction (sIUGR; Group 3), 2 intrauterine deaths not for fetal anomaly or maternal condition (Group 4). Fetal heart Doppler studies assessing AoI PI, MPI-conventional Doppler and MPI'-TDI were performed three times between 18 and 24 weeks of gestation. Delivery records and pediatric discharge reports of the patients were reviewed after delivery. Results: Fetal cardiac function was measured as MPI RV and LV, MPI' RV and LV, and AoI PI at a mean gestational age of 18.3 (range 17.1-20.5), 22.3 (21.1-23.5) and 24.3 (22.2-26.2) weeks. All the cardiac parameters were significantly different at 18 weeks in recipients versus controls except for MPI' RV, which was on the contrary the only cardiac parameter significantly different in donors. In recipients MPI RV, MPI LV, AoI PI and MPI' LV decreased significantly from 18 to 24 weeks' gestation. MPI'LV had the best sensitivity and negative predictive value in recipients at 18 weeks confirmed at 22 weeks. A significant improvement in recipients' cardiac function towards mean values in controls was demonstrated after fetoscopic laser photocoagulation (FLP) therapy. Conclusion: We described novel parameters of fetal cardiac function in uncomplicated monochorionic diamniotic pregnancies. We showed that in TTTS the donor's cardiac function is not grossly abnormal but in recipients it is abnormal at time of TTTS with normalization after FLP. We identified cardiac indices predictive of the subsequent development of TTTS, and suggest a possible role of these indices in the planning of monochorionic diamniotic pregnancy follow-up.