Advertisement

Fetal vascular responses to maternal nicardipine administration in the hypertensive ewe

      This paper is only available as a PDF. To read, Please Download here.

      Abstract

      Calcium channel blockers such as nicardipine act as arterial vasodilators and are effective in the treatment of hypertension. Although they are also effective tocolytic agents, fetal effects have not been fully studied. Fifteen chronically catheterized near-term ewes were studied. Maternal and fetal cardiorespiratory parameters were measured in the control period and again 15 minutes after maternal venous infusion of angiotensin II. Nicardipine 20 μg/kg/min was given over 2 minutes and maternal and fetal cardiorespiratory parameters and fetal blood flow were measured 5,30, and 60 minutes later. Nicardipine reversed maternal hypertension and produced transient tachycardia. Fetuses responded initially with transient bradycardia and then developed hypercapnia and acidemia (p<0.03) by 60 minutes after nicardipine. Fetal placental blood flow decreased and vascular resistance increased by 5 minutes after nicardipine but returned toward control values after 30 minutes. Unexpectedly we obesrved the death of five fetuses by 65 minutes after nicardipine. We conclude that the administration of nicardipine in the hypertensive ewe results in significant alterations of fetal cardiorespiratory status and placental function that may lead to acidemia.

      Key Words

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      Subscribe:

      Subscribe to American Journal of Obstetrics & Gynecology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect

      References

        • Klein W
        • Brandt D
        • Vrecko K
        • et al.
        Role of calcium antagonist in the treatment of essential hypertension.
        Circ Res. 1983; 52: 174
        • Antman EM
        • Stone PH
        • Mueller JE
        • et al.
        Calcium channel blocking agents in the treatment of cardiovascular disorders. Part I. Basic and clinical electrophysiologic effects.
        Ann Intern Med. 1980; 93: 875
        • Ulmsten U
        Treatment of normotensive and hypertensive patients with preterm labor using oral nifedipine, a calcium antagonist.
        Arch Gynecol. 1984; 236: 69-72
        • Harake B
        • Gilbert R
        • Ashwal S
        • et al.
        Nifedipine: effects on fetal and maternal hemodynamics in pregnant sheep.
        Am J Obstet Gynecol. 1987; 157: 1003
        • Parisi VM
        • Salinas JM
        • Stockmar EJ
        Placental vascular responses to nicardipine in the hypertensive ewe.
        Am J Obstet Gynecol. 1989; 161: 1039-1043
        • Rudolph AM
        • Heymann MA
        The circulation of the fetus in utero: methods for studying distribution of blood flow, cardiac output and organ blood flow.
        Circ Res. 1967; 31: 163-184
        • Buckberg GD
        • Luck JC
        • Payne DB
        • et al.
        Some sources of error with radioactive microspheres.
        J Appl Physiol. 1971; 31: 598
        • Allen GS
        • Ahn HS
        • Preziosi T
        • et al.
        Cerebral artery spasm—a controlled trial of nimodipine in patients with subarachnoid hemorrhage.
        N Engl J Med. 1983; 308: 619
        • Gelmers HJ
        Calcium channel blockers in the treatment of migraine headaches.
        Am J Cardiol. 1985; 55: 139B
        • Ducsay CA
        • Thompson JS
        • Wu AT
        • Novy MJ
        Effects of calcium entry blocker (nicardipine) tocolysis in rhesus macaques: fetal plasma concentrations and cardiorespiratory changes.
        Am J Obstet Gynecol. 1987; 157: 1482-1486
        • Ducsay CA
        • Cook MJ
        • Veille JC
        • et al.
        Cardiorespiratory effects of calcium channel blocker tocolysis in pregnant rhesus monkeys.
        in: Jones CT Nathanielsz PW The physiologic development of the fetus and newborn. Academic Press, London1985
      1. Wilcourt RJ, DiMarchi JM, Higgins IL, et al. Evaluation of the calcium entry blocker nifedipine in combination tocolytic therapy. Am J Obstet Gynecol (in press)

        • Skillman CA
        • Plessinger MA
        • Woods JR
        • et al.
        Effect of graded reductions in uteroplacental blood flow on the fetal lamb.
        Am J Physiol. 1985; 249: H1098