a1 Faculty of Medicine, Imperial College, Queen Charlotte's and Chelsea Hospital, London, UK
a2 Royal Brompton NHS Foundation Trust Hospital, London, UK
a3 Blizard Institute of Cell and Molecular Science, Barts and The London School of Medicine and Dentistry, London, UK
a4 Department of Obstetrics and Fetal Medicine, University Medical Center, Hamburg-Eppendorf, Germany
a5 Statistical Advisory Service, Imperial College, London, UK
We assessed vascular programming in genetically identical monochorionic twin pairs with twin-to-twin transfusion syndrome (TTTS) treated differently in utero by serial amnioreduction or fetal laser arterial photocoagulation. This case–control study re-assessed four twin groups at median 11 years comprising 20 pairs of monochorionic diamniotic twins: nine treated by amnioreduction (TTTS-amnio) and eleven by laser (TTTS-laser) with seven monochorionic and six dichorionic control pairs. Outcome measures were current blood pressure (BP), brachio-radial arterial stiffness derived from pulse wave velocity (PWV), resting microcirculation (Flux) and response to heating and post-occlusive reactive hyperaemia measured using laser Doppler. Potential confounders [PWV and BP at first study, current height, weight, heart rate and twin type (ex-recipient, ex-donor or heavier/lighter of pair)] were accounted for by Mixed Linear Models statistical methodology. PWV dichorionic > monochorionic (P = 0.024); systolic and diastolic BP dichorionic > TTTS-amnio and TTTS-laser (P = 0.004, P = 0.02 and P = 0.005, P = 0.02, respectively). Within-twin pair pattern of PWV discordance was similar in laser treated and dichorionic controls (heavier-born > lighter), opposite to TTTS-amnio and monochorionic controls. Flux monochorionic > dichorionic (P = 0.044) and heavier > lighter-born (P = 0.024). TTTS-laser and dichorionic diamniotic showed greatest hyperaemic responses (dichorionic > TTTS-amnio or monochorionic controls (P = 0.007, P = 0.025). Hyperaemic responses were slower in heavier-born twins (P = 0.005). In summary, monochorionic twins had lower BP, arterial stiffness and increased resting vasodilatation than dichorionic twins implying shared fetal circulation affects vascular development. Vascular responses in laser-TTTS were similar to dichorionic and opposite to TTTS-amnio suggesting a lasting effect of fetal therapy on vascular health.
(Received August 27 2011)
(Revised December 29 2011)
(Accepted February 21 2012)
(Online publication March 20 2012)
c1 Address for correspondence: Dr H. M. Gardiner, Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College, Queen Charlotte's and Chelsea Hospital, Du Cane Road, London W12 0HS, UK. (Email firstname.lastname@example.org)
† Study performed at Queen Charlotte's and Chelsea Hospital, Imperial College London, UK and Department of Obstetrics and Fetal Medicine, University Medical Centre, Hamburg-Eppendorf, Germany.