title: Assessment of fetal atrioventricular time intervals by tissue Doppler and pulse Doppler echocardiography: normal values and correlation with fetal electrocardiography.
abstract: OBJECTIVE
  To establish gestational age-specific reference values of normal fetal atrioventricular (AV) time interval by spectral tissue Doppler imaging (TDI) and pulse-wave Doppler (PD) methods, and to assess their correlation with signal-averaged fetal PR intervals (ECG).
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Tertiary centre for fetal cardiology. PATIENTS AND MEASURES: 131 pregnant women between 14 and 42 weeks' gestation underwent 196 fetal echocardiograms and 158 fetal ECG studies. TDI-derived AV intervals were measured as the intervals from atrial contraction (Aa) to isovolumic contraction (IV) and from Aa to ventricular systole (Sa) at the right ventricular free wall. PD-derived AV intervals were measured from simultaneous left ventricular inflow/outflow (in/out) and superior vena cava/aorta (V/AO) recordings.
  
  
  RESULTS
  Measurements were possible by ECG in 61%, by TDI in 100%, by in/out in 100% and by V/AO in 97% of examinations. Aa-IV correlated significantly better with PR intervals (y = 0.67x + 38.29, R(2) = 0.15, p < 0.0001, mean bias 8.0 ms) than did in/out (R(2) = 0.10, p = 0.002, bias 18.7 ms) and V/AO (R(2) = 0.06, p = 0.02, bias 12.4 ms). Gestational age and AV intervals were positively correlated with all imaging modalities (R(2) = 0.19-0.31, p < 0.0001).
  
  
  CONCLUSIONS
  This study showed the feasibility of fetal AV interval measurements by TDI, and established gestational age-specific reference data. TDI-derived Aa-IV intervals track ECG PR intervals more closely than PD-derived AV intervals and thus should be used as the ultrasound method of choice in assessing fetal AV conduction.
authors.affiliation: Division of Cardiology, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Nii
authors.forename: R M
authors.initials: RM
authors.lastname: Hamilton
authors.forename: L
authors.initials: L
authors.lastname: Fenwick
authors.forename: J C P
authors.initials: JC
authors.lastname: Kingdom
authors.forename: K S
authors.initials: KS
authors.lastname: Roman
authors.forename: E T
authors.initials: ET
authors.lastname: Jaeggi
mesh_terms: D016275:Atrial Function / Q000502:physiology*; D015148:Cardiotocography; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005865:Gestational Age; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D015588:Observer Variation; D011446:Prospective Studies; D012016:Reference Values; D016276:Ventricular Function / Q000502:physiology*