Fetal cardiovascular dysfunction in intrauterine growth restriction as a predictive marker of perinatal outcome and cardiovascular disease in childhood

Abstract

Most risk factors leading to cardiovascular disease are already present in childhood and the importance of early identification of pediatric cardiovascular risk factors is now well recognized. Hypertension in the child has been associated with substantial long-term health risks and considered an indication for lifestyle modifications. Current clinical guidelines contemplate screening for hypertension in children over 3 years of age, in order to provide strategies for promoting cardiovascular health, which can be integrated into comprehensive pediatric care. Interventions in the IUGR group could go from blood pressure monitoring before 3 years of age, recommending lack of exposure to other risk factors (secondary smoking, obesity), surveillance of catch-up growth or administration of hypotensors and specially, promoting exercise and physical activity. A recent randomized trial in a large cohort of children suggest that the inverse association of fetal growth with arterial wall thickness in childhood can be prevented by dietary ω-3 fatty acid supplementation over the first 5 years of life. IUGR is not listed among those conditions presumed to increase cardiovascular risk, in current guidelines. Considering IUGR affects 5-10% of all newborns, the findings of this study would affect thousands of children per year. Currently, there are no prenatal parameters described that may aid in selecting those fetuses with later hypertension and arterial remodeling that may benefit for early screening in infancy and other preventive measures or interventions.

Both fetal and child cardiovascular evaluations have proven to be reliable techniques for describing changes in IUGR; cardiovascular dysfunction has been found subclinically and may have implications for cardiovascular risk in future life. The main aim of this work was to evaluate cardiovascular function parameters in IUGR fetuses as predictors of perinatal and postnatal cardiovascular outcome. In order to do this, we looked to validate the reproducibility of measurements and techniques not previously described in IUGR fetuses (studies 1 and 2), to evaluate whether fetal cardiovascular parameters could help us predict perinatal outcome (study 3) and finally to assess the value of fetal echocardiography for prediction of postnatal cardiovascular risk factors, specifically hypertension and arterial remodeling (study 4). This thesis confirms previous studies showing fetal cardiac dysfunction can be documented by fetal echocardiography; it validates different methods for evaluating cardiac function in the fetus and demonstrates the predictive value of these parameters for perinatal and postnatal cardiovascular outcome. Our first study demonstrates for the first time the validity of M-mode to assess longitudinal axis motion in IUGR. It further confirms previous research that IUGR fetuses have a significant decrease in longitudinal myocardial motion, as part of the fetal cardiovascular adaptation to placental insufficiency. In our second study, both TDI and 2D-derived strain analysis demonstrated to be feasible and reproducible to evaluate deformation parameters in the fetal heart. Our third study evaluated the independent and combined contribution of fetal cardiovascular parameters to the prediction of early-onset IUGR perinatal mortality. The study suggests an algorithm illustrating the chances of perinatal death against gestational age and DV, which might help clinical decisions in the management of early-onset IUGR fetuses.

The fourth study provides, for the first time, evidence that fetal echocardiographic parameters are strongly associated to postnatal hypertension and arterial remodeling, which are recognized cardiovascular risk factors and surrogates for early-onset cardiovascular disease. It supports that a fetal cardiovascular score is strongly associated with the presence of postnatal hypertension and arterial remodeling at 6 months of age in IUGR. Echocardiographic parameters demonstrated a far better performance than perinatal factors and fetoplacental Doppler used for establishing the severity of IUGR.

Los fetos con restricción del crecimiento intrauterino (RCIU) presentan remodelamiento cardiovascular el cual persiste en la infancia y se ha asociado a enfermedades cardiovasculares en el adulto. La hipertensión en la infancia se ha demostrado como un factor de riesgo cardiovascular para la enfermedad adulta. Un seguimiento estricto junto con intervenciones en la dieta se ha demostrado mejora la salud cardiovascular en estos niños, sin embargo no todas las restricciones del crecimiento tienen hipertensión en la infancia. El objetivo principal de esta tesis es definir los parámetros con mayor utilidad de la ecocardiografía fetal para predecir hipertensión y remodelamiento arterial en infantes de 6 meses de edad con restricción del crecimiento intrauterino. Para esto, se realizó un estudio de cohorte incluyendo fetos con RCIU y controles, seguidos desde vida prenatal hasta los 6 meses de edad. La evaluación prenatal consistió en una ecocardiografía funcional completa. A los 6 meses de edad estos niños fueron evaluados para hipertensión y remodelamiento arterial. Posteriormente se realizó la construcción de un score cardiovascular para determinar desde vida prenatal aquellos niños con mayor riesgo a presentar hipertensión en vida postnatal y que pudieran requerir vigilancia o intervenciones.