title: Fetal cardiac development and hemodynamics in the first trimester.
abstract: OBJECTIVE
  To describe fetal cardiac and hemodynamic development in the first trimester of pregnancy.
  
  
  METHODS
  Forty-eight pregnancies were prospectively studied with transvaginal ultrasound and color Doppler. Fetal heart rate and size were documented together with the presence of inflow and outflow wave-forms and valve signals.
  
  
  RESULTS
  Heart rate and size showed a positive correlation with gestational age. At 6 weeks of gestation, 20% of the cardiac cycle was occupied by the isovolumic contraction time (ICT); the isovolumic relaxation time (IRT) occupied 16% and remained unchanged, while the ICT progressively shortened and was not measurable after 12 weeks. The peak inflow velocities had changed from monophasic to biphasic by 10 weeks of gestation. At 7 weeks of gestation, semilunar valves were detected in 10% of examinations and the atrioventricular valves in 3%. The detection rate for both valves at 12 weeks was > or = 90%. In pregnancies that miscarried, the detection rate for both was < 25%.
  
  
  CONCLUSIONS
  The Doppler signals that characterize the heart during the first trimester suggest effective heart compliance by 12 weeks. Normal valve development can be inferred from non-invasive Doppler recordings.
authors.affiliation: Department of Obstetrics and Gynecology, Pennsylvania Hospital, Philadelphia 19107, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Leiva
authors.forename: J E
authors.initials: JE
authors.lastname: Tolosa
authors.forename: C N
authors.initials: CN
authors.lastname: Binotto
authors.forename: S
authors.initials: S
authors.lastname: Weiner
authors.forename: L
authors.initials: L
authors.lastname: Huppert
authors.forename: A L
authors.initials: AL
authors.lastname: Denis
authors.forename: J C
authors.initials: JC
authors.lastname: Huhta
mesh_terms: D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000254:growth & development / Q000502:physiology*; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D018608:Ultrasonography, Doppler; D018615:Ultrasonography, Doppler, Color