title: Cardiac pathophysiology in twin-twin transfusion syndrome: new insights into its evolution.
abstract: OBJECTIVE
  In twin-twin transfusion syndrome (TTTS), unbalanced transfer of vasoactive mediators and fluid from the donor to the recipient cotwin alters their cardiovascular function. The aims of this study were to describe the impact of TTTS on fetal cardiac function in a large cohort of monochorionic-diamniotic (MCDA) pregnancies, and determine the early hemodynamic response to selective fetoscopic laser photocoagulation (SFLP).
  
  
  METHODS
  Echocardiography was performed in 145 MCDA pregnancies, including 26 uncomplicated MCDA, 61 TTTS Stages I+II and 58 TTTS Stages III+IV pregnancies, prior to SFLP for TTTS. Echocardiographic data after SFLP were available in a subset of 41/119 (34%) TTTS cases at a mean of 1.7 ± 1.9 days. Mitral (MAPSE) and tricuspid (TAPSE) annular systolic excursion, myocardial performance index (MPI), tissue Doppler velocities (E', A', S') and filling pressures (E/E') were measured and transformed into Z-scores. Ventricular pressure was estimated from peak atrioventricular regurgitation velocity.
  
  
  RESULTS
  Left ventricular hemodynamics of the recipient twin were affected in early TTTS. In all stages of TTTS, left MPI and E/E' of the recipient twin were elevated in comparison to those of the donor (all P < 0.05), with reduced recipient left S' in TTTS Stages III+IV (P < 0.001). Ventricular pressure was elevated for gestational age (median, 42 mmHg (range, 20-65 mmHg)) in 11 of 14 recipients in which this parameter was measured. Between-group difference in right ventricular E/E' was significant only in TTTS Stages III+IV recipients compared with TTTS Stages I+II (P = 0.007) and uncomplicated MCDA (P = 0.041). Recipient left and right MPI decreased while S', MAPSE and TAPSE increased after SFLP; in donors, left E/E' and cardiac output increased.
  
  
  CONCLUSIONS
  Cardiac function of the recipient twin in TTTS is abnormal, even in the early stages of the disease. Left ventricular filling pressures are elevated and systolic function is decreased before abnormalities in the right heart become apparent. SFLP produces rapid hemodynamic improvement. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.|Department of Obstetrics and Gynecology, Paracelsus Medical University Salzburg, Salzburg, Austria.
authors.forename: C
authors.identifier: http://orcid.org/0000-0002-3184-0980
authors.initials: C
authors.lastname: Wohlmuth
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.
authors.forename: D
authors.initials: D
authors.lastname: Boudreaux
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Moise
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.
authors.forename: A
authors.initials: A
authors.lastname: Johnson
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.
authors.forename: R
authors.initials: R
authors.lastname: Papanna
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bebbington
authors.affiliation: The Fetal Center, Children's Memorial Hermann Hospital and the Department of Obstetrics, Gynecology and Reproductive Science, UTHealth McGovern Medical School, Houston, TX, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Gardiner
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D015150:Echocardiography, Doppler; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging* / Q000196:embryology / Q000503:physiopathology*; D005865:Gestational Age; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D011247:Pregnancy; D014427:Twins; D016216:Ultrasonography, Prenatal
keywords: long-axis function; monochorionic; myocardial performance index; tissue Doppler; twin; twin-twin transfusion syndrome