The significance of intracardiac Doppler sonography in terms of fetal growth retardation

Abstract

The proper function of the fetal heart is indispensable for the fetal development and the normal fetal growth. For prenatal medicine, Doppler sonography offers the possibility of a non-invasive method to examine the fetal cardiovascular function under normal and pathological circumstances. The role of the Doppler sonography is to identify those fetuses who have a high risk factor for developing a pre- or intrapartual asphyxia and therefore have to be delivered promptly. This study aimed at evaluating the clinical value of the intracardiac Doppler sonography (IDS) and at scrutinizing its usefulness during the supervision of the pregnancy of intrauterine growth restricted (IUGR) fetuses. In a prospective research at the Medical School of Hanover, fetal IDS was applied to 174 pregnant women between the 21 and 37 weeks of gestation (WG). The e-wave and the a-wave, the E/A ratio, and the TVI (time velocity integral) were measured at the atrioventricular (AV) valves. The PV (peak velocity) as well as the TVI were determined at both the aortic and the pulmonary valve. Normal range curves were compiled for all measured parameters. Alongside a control group with untroubled gravidity, which consisted of 153 patients, IUGR fetuses, who formed a collective of 21 patients, were Doppler sonographically examined. While the gestational age advanced, an increase of both the e-wave and the a-wave above the AV-valves could be ascertained, which lead to an E/A ratio <1. Above the semilunar valves there was indicated a slight steady increase of the TPV, the PV as well as the TVI. Normal range curves, which largely correspond to those described in the literature, were compiled for the collective of the pregnancies without pathological findings (n = 153). In comparison to the standard collective, there were no significant differences from the collective of the growth restricted fetuses (n = 21). A temporal informational advantage of pathological intracardiac Doppler values for high risk pregnancies (IUGR) could not be retraced in the examined collective. Doppler sonography traces acute and chronic deficits, which are indicated by hemodynamic changes of the fetus's blood supply. The clinical importance of IDS as regards dystrophic fetuses has to be ascertained in continuative studies: In the stage of compensatory placental insufficiency (IUGR, arterial Doppler without ARED-flow, venous Doppler without pathological findings) the IDS cannot provide an informational advantage. Contrastingly, the diagnostic potential of the IDS as a screening method of fetal cardiac insufficiency during decompensative placental insufficiency (IUGR, arterial Doppler with ARED-flow, venous Doppler normal or pathological) remains indistinct and should therefore be prospectively evaluated within this high risk group and contrastingly compared to the significance of the venous Doppler sonography (informational advantage?).