title: Reference charts of gestation-specific tissue Doppler imaging indices of systolic and diastolic functions in the normal fetal heart.
abstract: BACKGROUND
  Assessment of fetal cardiac function is difficult because of limited accessibility. Tissue Doppler imaging (TDI) is a promising technique in assessing diastolic function in adults. There has been sparseness concerning the use of TDI in assessing fetal cardiac function. The aim of this study was to construct reference charts of TDI indices of systolic and diastolic functions of the normal fetal heart.
  
  
  METHODS
  Ventricular myocardial velocities at the left ventricular (LV) wall, right ventricular (RV) wall, and interventricular septum (IVS) were assessed by TDI in 302 subjects.
  
  
  RESULTS
  From 19 to 37 weeks of gestation, peak myocardial velocities during early diastole (Em) increased from 3.3 to 7.2, 3.9 to 8.3, and 3.2 to 5.0 m/s at the LV wall, RV wall, and IVS, respectively. Peak myocardial velocities during atrial contraction (Am) also increased throughout gestation, but the magnitude of increase was smaller (6.3 to 7.9, 7.7 to 10.6, and 5.5 to 5.9 m/s for the LV wall, RV wall, and IVS, respectively). As a consequence, the Em/Am ratio increased from 0.51 to 0.61 at midtrimester to 0.76 to 0.91 at term. Similar to Em, peak myocardial velocities during systole (Sm) also increased by almost 2 times from 18 to 37 weeks of gestation (3.8 to 6.0, 4.2 to 7.6, and 3.3 to 5.6 for the LV wall, RV wall, and IVS, respectively). Reference charts of gestation-specific Em, Am, Em/Am ratio, Sm, and E/Em were constructed accordingly.
  
  
  CONCLUSIONS
  In midtrimester, fetal diastolic function is predominantly contributed by atrial contraction. As gestation advances, ventricular relaxation becomes increasingly mature. Reference charts for TDI indices were constructed, these will allow identification of fetuses with an abnormal diastolic function.
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China. chanysl@ha.org.hk
authors.forename: Louis Yik-si
authors.initials: LY
authors.lastname: Chan
authors.forename: Wing Yee
authors.initials: WY
authors.lastname: Fok
authors.forename: John Tai-hung
authors.initials: JT
authors.lastname: Wong
authors.forename: Cheuk Man
authors.initials: CM
authors.lastname: Yu
authors.forename: Tse Ngong
authors.initials: TN
authors.lastname: Leung
authors.forename: Tze Kin
authors.initials: TK
authors.lastname: Lau
mesh_terms: D000328:Adult; D015150:Echocardiography, Doppler; D005260:Female; D006340:Heart Rate, Fetal; D006801:Humans; D009200:Myocardial Contraction; D011247:Pregnancy; D011446:Prospective Studies; D012016:Reference Values; D016216:Ultrasonography, Prenatal