Fetal Ventricular Diastolic Filling Characteristics in a Primate Model: The Role of Fetal Heart Rate and Pulmonary Vascular Impedance

Abstract

We hypothesized that fetal ventricular diastolic filling characteristics are related to fetal heart rate (FHR) and pulmonary vascular impedance. Rhesus monkeys underwent Doppler ultrasonography at near-term gestation. Tricuspid (TV) and mitral valve (MV) blood velocity waveforms were used to calculate maximum velocity (V-max) and velocity time integral (VTI) E/A ratios (early filling/ventricular filling during atrial contraction) at baseline and during maternal hyperoxygenation. Right pulmonary artery (RPA) pulsatility indices (PIs) and FHR were measured. Hyperoxgenation significantly decreased FHR and RPA PI. The TV V-max and the MV VTI E/A ratios increased significantly and correlated with a decrease in FHR but not with a decrease in RPA PI. The TV and MV A-wave V-max decreased during hyperoxygenation and their decrease correlated significantly with a drop in FHR. Fetal ventricular diastolic filling characteristics are related to FHR but not to pulmonary vascular impedance.