Longitudinal assessment of growth in hypoplastic left heart syndrome: results from the single ventricle reconstruction trial

Abstract

Background: We sought to characterize growth between birth and age 3 years in infants with hypoplastic left heart syndrome who underwent the Norwood procedure.

Methods and results: We performed a secondary analysis using the Single Ventricle Reconstruction Trial database after excluding patients <37 weeks gestation (N=498). We determined length-for-age z score (LAZ) and weight-for-age z score (WAZ) at birth and age 3 years and change in WAZ over 4 clinically relevant time periods. We identified correlates of change in WAZ and LAZ using multivariable linear regression with bootstrapping. Mean WAZ and LAZ were below average relative to the general population at birth (P<0.001, P=0.05, respectively) and age 3 years (P<0.001 each). The largest decrease in WAZ occurred between birth and Norwood discharge; the greatest gain occurred between stage II and 14 months. At age 3 years, WAZ and LAZ were <-2 in 6% and 18%, respectively. Factors associated with change in WAZ differed among time periods. Shunt type was associated with change in WAZ only in the Norwood discharge to stage II period; subjects with a Blalock-Taussig shunt had a greater decline in WAZ than those with a right ventricle-pulmonary artery shunt (P=0.002).

Conclusions: WAZ changed over time and the predictors of change in WAZ varied among time periods. By age 3 years, subjects remained small and three times as many children were short as were underweight (>2 SD below normal). Failure to find consistent risk factors supports the strategy of tailoring nutritional therapies to patient- and stage-specific targets.

Clinical trial registration url: http://clinicaltrials.gov/. Unique identifier: NCT00115934.

Keywords: growth; hypoplastic left heart syndrome; pediatrics; risk factors.

Figure 1.

A, Flow diagram showing the study sample used for the growth analysis from birth to age 3 years (without intermediate time points). B, Flow diagram showing the study sample used for the growth analysis for birth weight to each of the first 2 time periods: (1) Birth to Norwood discharge; (2) Norwood discharge to pre‐stage II. C, Flow diagram showing the study sample used for the growth analysis for pre‐stage II and the last 2 time periods: (1) Pre‐stage II to age 14 months, (2) Age 14 months to age 3 years. SVR indicates Single Ventricle Reconstruction.

Figure 2.

Graph demonstrating weight‐for‐age z score over all time periods and length‐for‐age z score at birth and age 3 years. Each mean is based on all data available at the respective time point, ranging from N=485 at birth to N=268 at age 3 years. The error bars represent one standard deviation. LAZ indicates length/height‐for‐age z score; WAZ, weight‐for‐age z score.