Large Left to Right Shunts...

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Large Left to Right Shunts and Congestive Heart Failure Increase Total Energy Expenditure in Infants with Ventricular Septal Defects.

Anne G. Farrell, MD, Marcus S. Schamberger, MD, Inger L. Olson, MD, Gregory J. Ensing, MD, Catherine A. Leitch, PhD. Dept. of Pediatrics, Indiana University School of Medicine, Indianapolis, IN.

Pediatrics 1998, 102(3)Suppl:678

Background: It has been suggested that increased energy expenditure and/or decreased caloric intake may be responsible for decreased growth often seen in patients with congenital heart disease and left to right shunting. We hypothesized that infants with moderate to large ventricular septal defects (VSD) being treated for congestive heart failure (CHF) would exhibit higher rates of total energy expenditure (TEE) than infants with small VSDs, infants with moderate to large VDSs but not CHF, or healthy control (CTL) infants.

Methods: Fifteen otherwise healthy 4 month old patients with isolated, unoperated VSDs and 10 age-matched, healthy CTLs were selected. Eight of the VSD infants were being treated for CHF. Anthropometric measurements and an echocardiogram were performed on all subjects. Left to right shunting (Qp:Qs) in VSD patients was quantified by either cardiac catheterization or echocardiography. Respiratory calorimetry was used to measure resting energy expenditure (REE), and the doubly labeled water method was used to measure TEE, energy intake (EI) and total body water (TBW). Daily urine samples were collected at home. Samples were analyzed by isotope ratio mass spectrometry.

Results: All values are expressed as mean+SD. Data were compared using ANOVA.

Group	Weight	TBW	REE	EI	TEE
	kg	%	kcal/kg/d	kcal/kg/d	kcal/kg/d
CTL (n=10)	6.8+1.4	59.7+6.4	43.9+14.1	87.0+11.8	61.9+10.2
VSD (n=15)	5.1+0.9	68.6+9.0	46.2+10.8	89.1+17.5	88.3+22.6
p	0.001	0.01			0.005

non-CHF (n=7)	5.6+0.6	63.5+8.8	44.3+7.5	82.3+12.2	76.4+18.3
CHF (n=8)	4.7+1.0	73.1+7.0	47.8+13.4	95.1+19.7	98.7+21.7
p	0.01	0.05

Qp:Qs<2.5 (n=9)	5.4+1.0	66.3+9.9	49.5+11.2	79.4+9.3	73.9+18.8
Qp:Qs>2.5 (n=6)	4.8+0.7	72.1+6.9	41.2+8.9	103.7+17.0	106.8+13.5
p				0.005	0.005

Conclusions: Infants with VSDs weigh significantly less, have a significantly higher %TBW and a significantly greater TEE than their healthy peers. Surprisingly, this increase in TEE is not accompanied by an increase in REE or energy intake. VSD infants being treated for CHF weigh significantly less and have a significantly higher %TBW than VSD infants without CHF; the TEE of the CHF group is 30% greater than that of the non-CHF group. Patients with large left to right shunts (Qp:Qs>2.5) also weigh less, have a higher %TBW and a significantly higher TEE than patients with smaller shunts, although this increase in TEE is somewhat offset by a significantly increased energy intake. The difference between TEE and REE largely reflects the energy cost of activity. This higher cost of activity, especially in infants with CHF and large left to right shunts, is a major factor leading to reduced growth in these infants, rather than increased REE or decreased caloric intake. Since the amount of physical activity increases with age, these infants may benefit from earlier surgical repair, since appropriate weight gain for surgery, despite optimal medical care, seems unlikely.

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