title: Speckle tracking-derived myocardial tissue deformation imaging in twin-twin transfusion syndrome: differences in strain and strain rate between donor and recipient twins.
abstract: OBJECTIVE
  Twin-twin transfusion syndrome (TTTS) is a complex disorder with altered cardiovascular loading conditions that affects both donors and recipients. Myocardial tissue deformation analysis using vector velocity imaging is an angle-independent, speckle-tracking technique which can assess myocardial mechanics and may provide insight into cardiac dysfunction in TTTS.
  
  
  METHODS
  Digital dynamic two-dimensional four-chamber views were interrogated offline. Images were acquired utilizing standard video frame rates (30 frames/s). The global longitudinal strain, systolic strain rate, and diastolic strain rate were measured in the left (LV) and right ventricles (RV) of 25 fetal pairs with TTTS and compared to 25 gestational age-matched normal controls. Pulsatility indices for the umbilical artery and middle cerebral artery were measured.
  
  
  RESULTS
  The gestational age at evaluation was 20.5 ± 1.3 weeks. The donor LV systolic strain rate was higher, while the donor RV diastolic strain rate was significantly lower, than control values. The recipient longitudinal strain, systolic strain rate, and diastolic strain rate were significantly lower for both LV and RV in comparison to controls. The donor umbilical artery pulsatility index was higher than control values (1.92 ± 0.45 vs. 1.41 ± 0.25, p < 0.001), while the donor middle cerebral artery pulsatility index was lower (1.46 ± 0.28 vs. 1.87 ± 0.21). Recipient umbilical artery and middle cerebral artery pulsatility indices were no different than control values.
  
  
  CONCLUSIONS
  In TTTS, both the donor and the recipient exhibit abnormalities of myocardial tissue deformation with ventricle-specific changes evident based on loading conditions. Donor LV systolic function is hyperdynamic due to hypovolemia and selective ejection into a low-resistance cerebrovascular circuit while the donor RV selectively ejects into a high-resistance placental circuit. Recipient RV and LV are both globally depressed with systolic and diastolic dysfunction. Further prospective validation of our findings using high frame rate analysis is indicated.
authors.affiliation: The Fetal Heart Program, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. rychik@email.chop.edu
authors.forename: Jack
authors.initials: J
authors.lastname: Rychik
authors.forename: Shi
authors.initials: S
authors.lastname: Zeng
authors.forename: Michael
authors.initials: M
authors.lastname: Bebbington
authors.forename: Anita
authors.initials: A
authors.lastname: Szwast
authors.forename: Michael
authors.initials: M
authors.lastname: Quartermain
authors.forename: Shobha
authors.initials: S
authors.lastname: Natarajan
authors.forename: Mark
authors.initials: M
authors.lastname: Johnson
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Tian
mesh_terms: D009202:Cardiomyopathies / Q000000981:diagnostic imaging* / Q000196:embryology / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology*; D005865:Gestational Age; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000196:embryology / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology; D009200:Myocardial Contraction; D015588:Observer Variation; D011247:Pregnancy; D011673:Pulsatile Flow; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000196:embryology / Q000503:physiopathology; D014672:Vectorcardiography / Q000379:methods; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000196:embryology / Q000209:etiology; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging / Q000196:embryology / Q000209:etiology; D014741:Video Recording