Doppler Echocardiography Assessment of Cardiac Sparing Effect in Fetal Hypoxia

The fetal heart plays a central role in the adaptive mechanisms for hypoxemia and placental insufficiency. Longitudinal data on the hemodynamic sequence of the natural history of fetal growth restriction show that the umbilical artery and middle cerebral artery are the first variables to become abnormal . These arterial Doppler abnormalities are followed by abnormalities in the right cardiac diastolic indices, followed by the right cardiac systolic indices, and finally by both left diastolic and systolic cardiac indices .

Preserving the left systolic function as the last variable to become abnormal ensures an adequate left ventricular output , which supplies the cerebral and coronary circulations.This defence is contingent on the fetal cardiovascular system, which in late gestation adopts strategies to decrease oxygen consumption and redistribute the cardiac output away from peripheral vascular beds and towards essential circulations, such as those perfusing the brain.

Adding cardiac Doppler may improve management of the IUGR fetus(intrauterine growth retardation), Doppler ultrasound is valuable in defining the degree of cardiovascular compromise in at-risk pregnancies. The severity of fetal blood flow redistribution shows the degree of fetal adaptation and provides information on how long the pregnancy can be continued safely.

The aime of the study is assessment of cardiac output redistribution in fetal hypoxia by estimating relative right to left side cardiac output wich reflect cardiac sparing in (IUGR).