Abstract 170 Poster Session III, Monday, 5/3 (poster 136)

We have previously shown that infants with moderate to large ventricular septal defects (VSD) have increased total energy expenditure (TEE) relative to healthy infants, with no differences in resting energy expenditure (REE) or energy intake (EI) between groups ( Pediatr 102:1172-7, 1998). We now hypothesize that (1) infants with VSDs being treated for congestive heart failure (CHF) would exhibit higher rates of TEE than VSD infants without CHF and (2) TEE will positively correlate with the magnitude of left to right shunting. Fifteen otherwise healthy 4 month old infants with isolated, unoperated VSDs and 10 age-matched healthy controls (CTL) were studied. Eight of the VSD infants were being treated for CHF. Left to right shunting (Qp:Qs) in VSD patients was quantified by cardiac catheterization or echocardiography. Respiratory calorimetry was used to measure REE; the doubly labeled water method was use to measure total body water (TBW), TEE and EI. Energy expended on physical activity (EA) was determined as the difference between TEE and REE.

RESULTS: Qp:Qs is positively correlated with both TEE and EA (r=0.74, p≤0.0001). All values are expressed as mean ± SD. Results were compared using 3-way ANOVA. (Table)

Table 1 No caption available
Full size table

CONCLUSIONS: Infants with VSD and CHF are smaller and leaner than infants without CHF or healthy CTL infants. No differences exist in REE among the groups. Energy intakes of VSD infants are similar to those of CTL infants and are appropriate for age. Large Qp:Qs and CHF increase TEE, but not REE in VSD infants. The difference between TEE and REE primarily reflects energy cost of physical activity. The energy cost of physical activity, rather than increased REE or decreased EI, leads to reduced growth in these infants. Since physical activity increases with age, these infants may benefit from early surgical repair, since appropriate weight gain for surgery seems unlikely despite optimal medical care.