title: The effect of fetal heart rate on the peak systolic velocity of the fetal middle cerebral artery.
abstract: OBJECTIVE
  To estimate the effect of an increase in the basal heart rate of the fetus on the middle cerebral artery peak systolic velocity (MCA-PSV).
  
  
  METHODS
  This was a prospective longitudinal cohort. Patients between 14 and 36 weeks of gestation were enrolled (N=66). Ultrasound examinations were performed monthly. MCA-PSV measurements were assessed at 0-degree angle of insonation at basal fetal heart rate and after application of vibroacoustic stimulation.
  
  
  RESULTS
  A total of 514 MCA-PSV measurements were obtained in 66 fetuses. No difference in fetal heart rate before and after vibroacoustic stimulation was noted before 27 weeks of gestation. A significant increase in fetal heart rate after vibroacoustic stimulation was detected from a mean+/-standard deviation gestational age of 27.1+/-1.3 weeks onward. A significant decrease in the MCA-PSV was noted between before vibroacoustic stimulation and after vibroacoustic stimulation measurements for examinations 3,4, and 5 (P<.001 for all).
  
  
  CONCLUSIONS
  Acceleration of the fetal heart rate in the third trimester is associated with a decrease in the middle cerebral artery peak systolic velocity. Assessment of the MCA-PSV for the detection of fetal anemia, particularly in the third trimester, should be undertaken during a period of baseline fetal heart rate to avoid the potential of a false-negative result.
  
  
  METHODS
  II.
authors.affiliation: From the Department of Maternal-Fetal Medicine, WakeMed Faculty Physicians, Raleigh, North Carolina; Perinatal Associates of New Mexico, Albuquerque, New Mexico; Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina; Carolina Population Center, University of North Carolina, Chapel Hill, North Carolina; Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina; Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Baylor College of Medicine, and the Texas Children's Fetal Center, Texas Children's Hospital, Houston, Texas.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Swartz
authors.forename: Michael S
authors.initials: MS
authors.lastname: Ruma
authors.forename: Eunhee
authors.initials: E
authors.lastname: Kim
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: M Kathryn
authors.initials: MK
authors.lastname: Menard
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Moise
mesh_terms: D000161:Acoustic Stimulation; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D020768:Middle Cerebral Artery / Q000196:embryology* / Q000502:physiology; D011247:Pregnancy; D011446:Prospective Studies; D013599:Systole / Q000502:physiology; D016216:Ultrasonography, Prenatal; D014732:Vibration