Effect of pregnancy on vascular responses in the offsprings of endothelial nitric oxide synthase knockout mice

Abstract

MEASUREMENTS DAVID CHAFFIN, Society for Maternal-Fetal Medicine, Huntington, WV OBJECTIVE: To evaluate the clinical outcomes of a program to pharmacologically manage hypertensive pregnant patients based on serial measurements of blood pressure, cardiac output (CO), and systemic vascular resistance (SVR) beginning in the second trimester. STUDY DESIGN: Patients were enrolled in the program based on a history of chronic hypertension, type 1 diabetes, chronic renal failure, or early severe preeclampsia. Blood pressure, cardiac output, and systemic vascular resistance were measured using thoracic electrical impedance plethysmography. Patients with hyperdynamic or mixed vasoconstrictive/hyperdynamic measurements at a gestational age of less than 24 weeks were treated with atenolol. Vasodilators were added for SVR >1100 dyne*sec*cm . Patients were followed on a regular basis until 34 weeks’ gestation with medication dosages adjusted to attempt to achieve normal hemodynamics. Patients were managed by referring physicians after 34 weeks. RESULTS: The first 106 patients treated with atenolol enrolled at less than 24 weeks are included in this report. Themean gestational age at enrollment was 16 ± 4 wks. The average mean arterial blood pressure was 99 ± 12 mm Hg. Initial cardiac output was 7.7 ± 1.5 liters/min (normal < 7.6 liters/min) with a range of 4.1 to 12.8 liters/min. Atenolol dosage ranged from 25 mg to 200 mg per day. Additional vasodilators used included hydralazine, nifedipine, and Isordil.Mean gestational age at delivery was 36 ± 3weeks with amean percentile birth weight of 47 (11% less than 10th centile). There were 4 patients delivered at less than 34 weeks for hypertensive complications. Three fetal deaths were due to premature labor at 22 to 23 weeks. 35 patients delivered between 34 and 37 weeks. The average hospital stay for these infants was 3.5 days (2.5 days for term infants). CONCLUSION: Early intervention with atenolol in an at-risk population with abnormal hemodynamics results in a low rate of early hypertensive complications with no increase in growth restriction.