TOTAL RUT NOT RESTING ENERGY-EXPENDITURE IS INCREASED IN INFANTS WITHVENTRICULAR SEPTAL-DEFECTS

Objective. The purpose of this study was to determine the effect of le ft-to-right shunting on the resting energy expenditure (REE), total en ergy expenditure (TEE), and energy intake in a group of 3- to 5-month- old infants with moderate to large unrepaired ventricular septal defec ts (VSDs) compared with age-matched, healthy infants. Methods. Eight i nfants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure RE E and the doubly-labeled water method was used to measure TEE and ener gy intake. An echocardiogram and anthropometric measurements were perf ormed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrom etry. Data were compared using analysis of variance. Results. No signi ficant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; con trol, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kc al/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The per cent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in th e VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal /kg/d). The difference between TEE and REE, reflecting the energy of a ctivity, was 2.5 times greater in the VSD group. Conclusions. REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infa nts suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants wi th VSDs may match the energy intake of healthy infants, they are unabl e to meet their increased energy demands, resulting in growth retardat ion.