CARDIAC AND HEMODYNAMIC CHANGES

ASSOCIATED WITH IUGR

(Parameters used to measure fetal cardiac function)
 Uteroplacental insufficiency
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Selective modifications in cardiac hemodynamics

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Cerebral vasodilatation  (S/D ratio in MCA decreases)	Peripheral vasoconstriction (S/D ratio in Aorta increases)	* Hypoxemia may impair myocardial  contractility
Decreased LV afterload	Increased RV afterload	* Polycythemia may alter blood viscosity and preload

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E/A ratio at tricuspid valve Decreases

Peak velocity in the aorta and pulmonary  artery Decreases

Time to peak velocity in the aorta and pulmonary artery Increases

Left cardiac output Increases

Right cardiac output Decreases

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Preferential shift of cardiac output in favor of LV (Normally ratio of right to left cardiac output = 1.3:1). This increases perfusion to the brain and heart and maintains oxygen and substrate supply despite a decrease in placental transfer)

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Further deterioration

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Impaired cardiac filling

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IVC (increased reverse flow during atrial contraction due to a higher pressure gradient in the right atrium)

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Ductus venosus (Increased S/A ratio due to a decreased A component)

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Umbilical vein (Decreased velocity at end diastole with pulsations)

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 Fetal heart rate anomalies (frequently associated with acidemia at birth)