V-shaped deceleration differs in the pattern of carotid blood flow from variable deceleration provoked by cord compression.
OBJECTIVE
To investigate whether V-shaped decelerations in fetal heart rate tracing are a physiologic response to fetal movements or secondary to cord compression.


METHODS
Six pregnant sheep and their fetuses (115-125 days of gestation) were surgically instrumented and studied. Fetal electrocardiogram, carotid blood flow, arterial blood pressure and fetal movement were continuously monitored for 24 hours. Following the undisturbed 24 hour recording, these parameters were monitored during umbilical cord compression (n = 6). Differences in these parameters between V-shaped decelerations and decelerations provoked by cord compressions were examined.


RESULTS
Elevation of blood pressure and decreased carotid blood flow were observed coincidentally with the initiation of V-shaped decelerations. In cord compression, elevation of both blood pressure and carotid blood flow were followed by a decreased heart rate. V-shaped decelerations exhibited a different alteration of carotid blood flow compared to decelerations caused by umbilical cord compression.


CONCLUSIONS
V-shaped deceleration is a physiologic response secondary mainly to fetal movements and is not caused by cord compression.
Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, 1-1 Seiryomachi, Aobaku, Sendai, Japan. tomoharu@ob-gy.med.tohoku.ac.jp
Tomoharu
T
Yasui
Yoshitaka
Y
Kimura
Jun
J
Murotsuki
Takanori
T
Watanabe
Takahiro
T
Koshino
Kunihiro
K
Okamura
D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D002339:Carotid Arteries / Q000196:embryology* / Q000502:physiology; D003250:Constriction; D004576:Electromyography; D005260:Female; D005324:Fetal Movement; D006340:Heart Rate, Fetal; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000097:blood; D011247:Pregnancy; D012756:Sheep; D014470:Umbilical Cord / Q000502:physiology*
D002245:Carbon Dioxide; D010100:Oxygen