Nifedipine disturbs fetal cardiac function during hypoxemia in a chronic sheep model at near term gestation.

Structured Abstract Background Nifedipine is widely used drug in pregnancies complicated by maternal hypertensive disorders that can be associated with placental insufficiency and fetal hypoxemia. The evidence regarding fetal myocardial responses to nifedipine in hypoxemia is limited. Objective We hypothesized that nifedipine would not impair fetal sheep cardiac function under hypoxemic environment. Especially, we investigated the effects of nifedipine on fetal ventricular functional parameters and cardiac output. Study Design A total of 21 chronically instrumented fetal sheep at 122-134 gestational days (term 145 days) were included in this study. Fetal cardiac function was evaluated by measuring global longitudinal strain, indices describing ventricular systolic and diastolic function, and cardiac outputs using 2D speckle tracking, and tissue and spectral pulsed-wave Doppler echocardiography. Fetal carotid artery blood pressure and blood gas values were invasively monitored. After baseline data collection, fetal hypoxemia was induced by maternal hypoxygenation. Following hypoxemia phase data collection, 9 fetuses received nifedipine infusion, and 12 fetuses received saline infusion. Data were collected 30 and 120 minutes after the infusion was started. After 120 minutes data collection, maternal and fetal oxygenation were normalized, and normoxemia phase data were collected, while infusion was continued. Results Hypoxemia decreased fetal carotid artery mean arterial pressure from 40 (8) mmHg to 35 (8) mmHg (p Conclusions In hypoxemic fetus, nifedipine impaired right ventricular function and reduced its cardiac output. The detrimental effects of nifedipine on fetal right ventricular function were abolished, when normoxemia was restored. Our findings suggest that in hypoxemic environment nifedipine triggers detrimental effects on fetal right ventricular function.