Evaluation of cardiac performance by abdominal fetal ECG in twin-to-twin transfusion syndrome

Objective: To investigate fetal cardiac performance by abdominal fetal electrocardiography (ECG) in monochorionic diamniotic pregnancies with twin-to-twin transfusion syndrome (TTTS-MCDA). Methods: Abdominal fetal ECG was attempted in 16 singleton, 21 non-TTTS-MCDA, and 14 TTTS-MCDA pregnancies at 16-27 weeks' gestation. Standard ECG parameters were compared across study groups and evaluated for their correlation with Doppler ultrasound indices. Results: Clear P-QRST complexes were recognized in all cases. In the TTTS-MCDA pregnancies, the QT interval and QTc were significantly longer than in both singletons and the non-TTTS-MCDA pregnancies (p=0.002 and p=0.0002, respectively), whereas in the recipient fetus, both the PR interval and PR/RR were significantly longer when compared with all other study groups (p=0.019 and p=0.012, respectively). Further comparison with Doppler ultrasound indices yielded significant reciprocal correlations between ductus venosus pulsatility index and the QT interval (r=0.552, p=0.041) and between umbilical artery pulsatility index and PR/RR (r=0.654, p=0.011) both demonstrated in recipient fetuses alone. Conclusions: Abdominal fetal ECG is feasible in second-trimester twin pregnancies. In TTTS, there is evidence of a higher risk of cardiac dysfunction in the recipient twin.