title: Color Tissue Doppler to Analyze Fetal Cardiac Time Intervals: Normal Values and Influence of Sample Gate Size.
abstract: To assess the time intervals of the cardiac cycle in healthy fetuses in the second and third trimester using color tissue Doppler imaging (cTDI) and to evaluate the influence of different sizes of sample gates on time interval values.
  
  
  
  Time intervals were measured from the cTDI-derived Doppler waveform using a small and large region of interest (ROI) in healthy fetuses.
  
  
  
  40 fetuses were included. The median gestational age at examination was 26 + 1 (range: 20 + 5 - 34 + 5) weeks. The median frame rate was 116/s (100 - 161/s) and the median heart rate 143 (range: 125 - 158) beats per minute (bpm). Using small and large ROIs, the second trimester right ventricular (RV) mean isovolumetric contraction times (ICTs) were 39.8 and 41.4 ms (p = 0.17), the mean ejection times (ETs) were 170.2 and 164.6 ms (p < 0.001), the mean isovolumetric relaxation times (IRTs) were 52.8 and 55.3 ms (p = 0.08), respectively. The left ventricular (LV) mean ICTs were 36.2 and 39.4 ms (p = 0.05), the mean ETs were 167.4 and 164.5 ms (p = 0.013), the mean IRTs were 53.9 and 57.1 ms (p = 0.05), respectively. The third trimester RV mean ICTs were 50.7 and 50.4 ms (p = 0.75), the mean ETs were 172.3 and 181.4 ms (p = 0.49), the mean IRTs were 50.2 and 54.6 ms (p = 0.03); the LV mean ICTs were 45.1 and 46.2 ms (p = 0.35), the mean ETs were 175.2 vs. 172.9 ms (p = 0.29), the mean IRTs were 47.1 and 50.0 ms (p = 0.01), respectively.
  
  
  
  Isovolumetric time intervals can be analyzed precisely and relatively independent of ROI size. In the near future, automatic time interval measurement using ultrasound systems will be feasible and the analysis of fetal myocardial function can become part of the clinical routine.
authors: Department of Obstetrics and Prenatal Medicine, University of Bonn, Germany.
authors: Arne Michael
authors: AM
authors: Willruth
authors: Department of Fetal Cardiology, Heart and Diabetes Centre North Rhine-Westphalia, Bad Oeynhausen, Ruhr-University Bochum, Germany.
authors: Johannes
authors: J
authors: Steinhard
authors: Division of Prenatal Medicine, Department of Obstetrics and Gynecology, Justus- LiebigUniversity and UKGM, Giessen, Germany.
authors: Christian
authors: C
authors: Enzensberger
authors: Division of Prenatal Medicine, Department of Obstetrics and Gynecology, Justus- LiebigUniversity and UKGM, Giessen, Germany.
authors: Roland
authors: R
authors: Axt-Fliedner
authors: Department of Obstetrics and Prenatal Medicine, University of Bonn, Germany.
authors: Ulrich
authors: U
authors: Gembruch
authors: Toshiba Medical Systems Europe, Germany.
authors: Astrid
authors: A
authors: Doelle
authors: Department for Medical Biometry, Informatics and Epidemiology, University of Bonn, Germany.
authors: Ioanna
authors: I
authors: Dimitriou
authors: Department for Medical Biometry, Informatics and Epidemiology, University of Bonn, Germany.
authors: Rolf
authors: R
authors: Fimmers
authors: Department of Obstetrics and Gynecology, Bürgerhospital, Frankfurt, Germany.
authors: Franz
authors: F
authors: Bahlmann
mesh_terms: D015150:Echocardiography, Doppler; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012016:Reference Values; D016216:Ultrasonography, Prenatal