Aortic Isthmus Doppler Velocimetry in Fetuses with Intrauterine Growth Restriction: A Literature Review.

Renato Augusto Moreira De Sá,Mariana Martins Ferraz,Paulo Roberto Nassar De Carvalho,Flávia Do Vale Araújo

doi:10.1055/s-0040-1710301

Renato Augusto Moreira De Sá, Mariana Martins Ferraz + Show 2 more

Open Access

https://doi.org/10.1055/s-0040-1710301

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Abstract

Intrauterine growth restriction (IUGR) is associated with poor perinatal prognosis and a higher risk of stillbirth, neonatal death, and cerebral palsy. Its detection and the evaluation of its severity by new Doppler velocimetric parameters, such as aortic isthmus (AoI), are of great relevance for obstetrical practice. The AoI is a vascular segment that represents a point of communication between the right and left fetal circulations. It is considered to be a functional arterial shunt that reflects the relationship between the systemic and cerebral impedances, and has recently been proposed as a tool to detect the status of hemodynamic balance and prognosis of IUGR in fetuses. In the present review, we noticed that in healthy fetuses, the AoI net flow is always antegrade, but in fetuses with IUGR the deterioration of placental function leads to progressive reduction in its flow until it becomes mostly retrograde; this point is associated with a drastic reduction in oxygen delivery to the brain. The more impaired the AoI flow is, the greater is the risk of impairment in the Doppler velocimetry of other vessels; and the alterations of the AoI Doppler seem to precede other indicators of severe hypoxemia. Although there seems to be an association between the presence of retrograde flow in the AoI and the risk of long-term neurologic disability, its role in the prediction of perinatal morbi-mortality remains unclear. The AoI Doppler seems to be a promising tool in the management of fetuses with IUGR, but more studies are needed to investigate its employment in clinical practice.

Highlights

Intrauterine growth restriction (IUGR) can be defined as the failure of a fetus to achieve its full growth potential and can be caused by placental, chromosomal, or environmental factors
It is clear that the predominant flow in the aortic isthmus (AoI) is always antegrade in fetuses without any pathology and that as gestational age advances, there is a physiological reduction in its diastolic flow, resulting in a reduction in isthmic flow index (IFI) and an elevation of AoI-pulsatility index (PI)
For fetuses affected by IUGR, there is a trend for the AoI to show lower velocity indices (e.g., peak systolic velocity (PSV), EDV, and TAMX) and higher resistance indices (PI and RI)

Summary

Introduction

Intrauterine growth restriction (IUGR) can be defined as the failure of a fetus to achieve its full growth potential and can be caused by placental, chromosomal, or environmental factors. This condition is associated with a poor perinatal outcome, and it is responsible for 50% of intrauterine demise; it elevates the risks of intrapartum fetal distress, emergency caesarian section, cerebral palsy, and perinatal death.[1,2] its detection and the determination of its severity are of major relevance for obstetric practice and constitute an opportunity for intervention to prevent unpleasant perinatal outcomes. Since there is no effective intrauterine treatment for IUGR caused by placental insufficiency, the aim of Doppler fetal monitoring is to detect the moment of hemodynamic decompensation at which the risk of maintaining the concept of a hypoxic environment should be balanced against risks related to prematurity caused by the interruption of gestation.[2,3,5,6]

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