Cardiac Hypertrophy and Altered Hemodynamic Adaptation in Growth-Restricted Preterm Infants

Abstract

The objective was to elucidate hemodynamic adaptation in very low birth weight (Ͻ1500 g) infants after intrauterine growth retardation. 31 growth-retarded (SGA, birth weight Ͻ-2 SD) and 32 appropriate for gestational age (AGA, birth weight within Ϯ 1 SD range) infants were enrolled. In SGA infants, the diastolic diameters of the interventricular septum and the left ventricle were increased, and serum brain natriuretic peptide (BNP) was elevated. Left ventricular output (LVO) of the AGA infants increased from 150 Ϯ 28 to 283 Ϯ 82 mL/kg/min during the study (p Ͻ 0.01). The SGA infants had a higher initial LVO than the AGA infants (243 Ϯ 47 versus 150 Ϯ 28 mL/kg/min, p Ͻ 0.05), but did not show further LVO increase during the study period. Red cell (RCV) and blood (BV) volume were assessed by Hb subtype analysis, when packed donor red cells were transfused. RCV and BV did not differ between the groups initially, but RCV increased by 18% and BV by 29% in the AGA group during the first 3 d. On day 3, AGA infants had larger BV than the SGA infants (88 Ϯ 5 versus 73 Ϯ 12 mL/kg, p Ͻ 0.05). In conclusion, cardiac hypertrophy, elevated initial LVO and BNP of the SGA infants suggest increased cardiac workload after intrauterine growth retardation. Based on the BV and RCV data, blood volume regulation may also be impaired. The data suggest that SGA preterm infants may be exposed to an increased risk of circulatory failure during early adaptation. Intrauterine growth retardation is associated with increased neonatal mortality, perinatal complications and long-term neurologic sequelae in preterm infants (1), as well as compromised cardiovascular adaptive capacity already in utero (2-4). However, few data have been reported regarding early circulatory adaptation after intrauterine growth retardation. In addition to myocardial performance, adequate intravascular volume is essential for successful postnatal cardiovascular adaptation. Largely due to the lack of applicable methodology, present knowledge on intravascular volume of preterm infants in general is scarce, and the effect of growth retardation on circulating volume has not been studied.The aim of the present study was to test the hypothesis that fetal growth retardation alters the pattern of early hemodynamic adaptation of very low birth weight infants. During the first two weeks of life, left ventricular function and dimensions were assessed by echocardiography in SGA infants and AGA control infants. A circulating indicator of ventricular dysfunction, BNP, was also measured. RCV and BV were determined by a method based on dilution of autologous HbF by donor HbA when red cells were transfused based on clinical judgment. Hemodynamic evaluation was also performed by using indirect indices applied in routine clinical work. METHODS Patients.All infants in the study were born in the maternal unit of the Helsinki University Hospital and treated in the

The cardiothoracic ratio in AGA and SGA very low birth weight newborn infants

“…It was suggested that the increased cardiac size in IUGR fetuses could be due to a 'sparing effect'. A study published by Leipala et al 7 also found increased cardiac size in growth-restricted preterm infants and suggested that such findings may be due to in utero changes of peripheral vascular resistance in accordance with the 'brain-sparing' effect of IUGR. It has also been shown that maternal undernutrition from early-to mid-gestation leads to cardiac hypertrophy in fetal sheep.…”

Cardiac Blood Flow Measurements in Stable Full Term Small for Gestational Age Neonates

“…Secondly, the subjects who were included in the previous studies were healthy full term infants and preterm infants, populations which were different from those of our study. Thirdly, recent studies have demonstrated that foetuses and newborns with severe forms of growth restriction have significant changes in their cardiac function parameters [19][20][21].…”

“…There is also a need of following up these cardiac blood flow measurements serially, throughout infancy, at regular intervals, to know the correlation of these flows with adult onset cardiovascular disease. Barker's hypothesis on foetal programming of adult disease mainly emphasizes on SGA neonates and recent studies have demon strated that foetuses and newborns with severe forms of growth restrictions have significant changes in foetal cardiac function parameters [19][20][21]. The functional echocardiography parameters in these SGA neonates would be non-invasive clinical parameters, which will help in serial monitoring of their cardiovascular statuses in various disease states.…”

Does B-type Natriuretic Peptide Level Predict Outcome After Arterial Switch Operation ?

“…Recently a study in patients with congenital heart defects amenable to biventricular repair indicated that measurement of circulating levels of BNP can predict the development of low cardiac output syndrome (LCOS) and prolonged mechanical ventilation (5).Furthermore, other studies indicated higher plasma level of BNP in children with congenital heart disease and newborns with severe fetal distress (6)(7)(8).Because of serious complications related to congenital cardiac defects, surgical repair or palliation of congenital cardiac defects is carried out usually during the neonatal period (8)(9).Moreover, neonates,compared to infants and children, have more adverse events and perioperative mortality.…”

“…On the other hand,the clinical predictive value of perioperative plasma BNP levels in neonates, who are most at risk for unpredictable adverse outcomes, is controversial [5][6][7][8][9][10] . So, we steered this study to address these concerns and to shed light on predictive value of preoperativeBNP plasma level in patients under cardiac surgery .…”