Ventriculovascular physiology of the growth-restricted fetus

Objectives To examine the mechanisms by which intrauterine growth restricti on may influence later cardiovascular risk by comparing the ventriculovascu lar physiology of gestational age- and weight-matched growth-restricted and normal fetuses. Design A prospective longitudinal observational stud.), of 20 normal fetuse s studied from 20 weeks to term at monthly intervals was compared with a gr owth-restricted cohort examined in the interval between diagnosis and deliv ery. The last values before delivery of the growth-restricted cohort were c ompared with the normal cohort in two analyses matched for weight and for g estation. Arterial and venous vessel wall physiology and aortic pulse wave velocity were examined longitudinally in the thoracic descending aorta and inferior vena cava using an ultrasonic phase-locked echo-tracking system. S erial echocardiographic examinations were performed assessing structure, ve ntricular dimensions; function and Doppler flows. Results There was a linear increase in cardiac preload and relative pulse a mplitude in the inferior vena cava with gestation. In normal fetuses, the a ortic pulse wave velocity, maximum incremental and late decremental velocit ies increased with gestation whilst the relative pulse amplitude decreased reflecting falling distal impedance. In both age- and weight-matched analys es, the growth-restricted fetuses showed significantly reduced values refle cting the chronic fetal ventriculovascular responses to increased placental impedance. Pulse wave velocity increased with gestation and was significan tly less in the growth-restricted cohort. Conclusions Growth restriction is associated with abnormal ventriculovascul ar physiology that represents a successful adaptive response to raised plac ental impedance and reduction in wall stress as evidenced by the lower feta l pulse wave velocity in growth-restricted fetuses. However, whilst fetal a daptive mechanisms may, aid survival the), may result in cerebral and vascu lar abnormalities that prejudice later cardiovascular health.