Experimentally induced intermittent sinusoidal heart rate pattern and sleep cycle in fetal lambs.
OBJECTIVE
Intermittent sinusoidal heart rate pattern, an early indicator of fetal anemia, has been speculated to have a positive correlation with fetal sleep cycles. To test this hypothesis, intermittent sinusoidal heart rate patterns were produced experimentally with arginine vasopressin in six methylatropinized fetal lambs that were demonstrating clear rapid-eye-movement and non-rapid-eye-movement sleep cycling.


METHODS
Eleven trials of arginine vasopressin infusion (40 to 160 mIU per body per minute) were performed on each of six chronically instrumented fetal lambs subsequent to parasympathetic blocking doses of methylatropine (300 to 400 micrograms). An intermittent sinusoidal heart rate pattern was observed in relation to fetal sleep cycles.


RESULTS
Alteration between rapid-eye-movement and non-rapid-eye-movement sleep was observed in methylatropinized fetuses. In the six fetuses that showed intermittent sinusoidal heart rate patterns subsequent to arginine vasopressin infusion, the fetal heart rate tracing and fetal electrocorticogram demonstrated alternate sinusoidal pattern and reactive heart rate patterns during high- and low-voltage electrocorticogram activity, respectively.


CONCLUSIONS
These findings support the hypothesis that fetal sleep cycling has a positive correlation with the periodic appearance of intermittent sinusoidal heart rate patterns.
Ninomiya
Y
Y
Department of Obstetrics and Gynecology, University of California, Irvine, College of Medicine, Orange 92613-1491.
Murata
Y
Y
Wakatsuki
A
A
Masaoka
N
N
Porto
M
M
Tyner
J G
JG
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D005260:Female; D006340:Heart Rate, Fetal / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D012756:Sheep; D012894:Sleep Stages / Q000502:physiology*
D001127:Arginine Vasopressin