The PR interval–fetal heart rate relationship during repetitive umbilical cord occlusions in immature fetal sheep

• Published in: European journal of obstetrics & gynecology and reproductive biology 2000-03, Vol.89 (1), p.69-74
• Main Authors: Keunen, Han, van Wijngaarden, Willem J., Sahota, Daljit S., Hasaart, Tom H.M.
• Format: Article
• Language: English
• Subjects: Acidosis - etiology; Animals; Asphyxia; Biological and medical sciences; Constriction; Diseases of mother, fetus and pregnancy; Electrocardiogram; Electrocardiography; Female; Fetal sheep; Gestational Age; Gynecology. Andrology. Obstetrics; Heart Rate, Fetal; Hypotension - etiology; Immature; Kinetics; Medical sciences; Pregnancy; Pregnancy. Fetus. Placenta; Sheep - embryology; Umbilical Cord - physiology
• ISSN: 0301-2115; 1872-7654
• DOI: 10.1016/S0301-2115(99)00160-8

Objective: To evaluate the relationship of the PR interval and fetal heart rate during repetitive umbilical cord occlusions in immature sheep fetuses. Study design: In seven chronically cannulated immature sheep fetuses [gestational age 90.6 days (mean)], we analyzed continuous fetal electrocardiogram recordings during repetitive cord occlusions for 2 out of every 5 min until fetal mean arterial pressure dropped to 50% of baseline value. PR interval–fetal heart rate correlation coefficients (Pearson) was measured on consecutive blocks of 2.5 min. R-values of the baseline and the repetitive occlusion period were compared by Fisher’s exact test. Results: Repetitive cord occlusions resulted in acidosis and hypotension. Two fetuses died at the end of the repetitive occlusion period. Four out of seven fetuses showed a significant change from a negative relationship between the PR interval and fetal heart rate during baseline to a predominantly positive relationship during the repetitive occlusion period. Conclusion: In immature fetal sheep, a change from a negative relationship between the PR interval and fetal heart rate to a predominantly positive relationship between the PR interval and fetal heart rate was observed in four out of seven fetuses following the initiation of repetitive umbilical cord occlusions.