The effect of fetal heart rate on the peak systolic velocity of the fetal middle cerebral artery.
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.
Swartz
Anthony E
AE
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.
Ruma
Michael S
MS
Kim
Eunhee
E
Herring
Amy H
AH
Menard
M Kathryn
MK
Moise
Kenneth J
KJ
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