Bioelectrical Impedance Analysis and How it Correlates to Intracardiac Hemodynamics in Patients with Congenital Heart Disease

Bioelectrical impedance analysis (BIA) is a noninvasive tool that can estimate volume status using fluid compartment ratios. Previous studies have demonstrated that BIA can be used to help manage heart failure using the edema index (EI), which is the ratio of extracellular water (ECW) to total body water (TBW). This study set out to better define the relationship between BIA fluid compartment estimations and invasive hemodynamic measurements, in the context of pediatric and congenital heart disease. 52 individuals underwent 59 elective catheterizations and BIA. Data from the BIAs were compared with the hemodynamic catheterization data. The median age at the time of catheterization was 16.6 [13.5, 19.6] years (63% < 18 years-old), and 29% were female. In multivariable analysis, EI (β = 103.5 ± 47.9, p = 0.04), body mass index (BMI) (β = 0.16 ± 0.07, p = 0.02), and current Fontan circulation (β = 3.06 ± 0.96, p = 0.002) were statistically significant predictors of pulmonary capillary wedge pressure (PCWP). Individuals with an EI ≥ 0.39 had a statistically significant higher PCWP compared to those with an EI < 0.39 (12 [11, 17] vs. 10 [8, 12], = 0.05), with an area under the curve (AUC) of 0.76 (95% CI 0.65, 0.87). There was no statistically significant mean difference between the pre-catheterization and either post-catheterization EI (- 0.0001 mean difference (0% change), p = 0.92), or body fat mass (BFM) (+ 0.035 mean difference (0.2% change), p = 0.81). This study suggests that BIA, and more specifically EI, can noninvasively provide valuable information about hemodynamic data. BIA provides a quick, easy, non-invasive method for assessing and managing the volume status in individuals with congenital heart disease.