P2A089: Ventricular Dimensions and Stroke Distance: Simple Prognostic Indices in Congenital Diaphragmatic Hernia

Background: Congenital diaphragmatic hernia (CDH) is associated with considerable mortality and morbidity, mainly due to pulmonary hypoplasia and pulmonary hypertension. Recently, smaller left ventricle (LV) size due to compression from an enlarged right ventricle (RV) and LV dysfunction have been shown to be associated with poor prognosis. Stroke distance (SD), a simple Doppler measure correlates well with the cardiac output. Our aim was to evaluate the prognostic utility of biventricular SD and dimensions in neonates with CDH.

Methods: This was a single center retrospective study of early ( < 48 hours age) Doppler ECHOs of neonates (≥34 weeks gestation) with CDH (n = 58). Patients with known congenital heart defects (except patent ductus arteriosus or foramen ovale) were excluded. Neonates (n=41) who underwent echocardiograms ( < 48 hours age) for murmurs, which were determined to be normal, acted as controls. A single reader blinded to clinical data evaluated the echocardiograms. SD, a product of velocity time integral (VTI) and heart rate (HR), was obtained for LV and RV. VTI was measured from an apical 5-chamber view with the pulse Doppler just below the aortic valve (LV) or pulmonary valve (RV) leaflet. RV and LV internal diameters were obtained in parasternal short axis at the level of papillary muscle in end-systole and end-diastole and their ratios calculated. Fractional area change (FAC) for both LV and RV were determined as markers of function. Our primary outcome was the composite outcome of death or ECMO. Echocardiographic measures were compared between groups with and without the primary outcome using student t-test and Chi-square test. A p value < 0.05 was considered significant.

Results: Our study cohort (n=57) comprised 32 (56%) males, while the 41 controls included 22 (54%) males. LV VTI and LV and RV stroke distance, LV diameters at end-systole and end-diastole were significantly reduced while RVLV dimension ratios were increased in the CDH group, compared to controls. In the CDH group, 32 (56%) died or required ECMO; 25 (44%) died. RVLV ratio in diastole was higher and RV as well as LV fractional area changes were lower in those who died or received ECMO, compared to survivors without ECMO.

Conclusion: Compared to controls, neonates with CDH have abnormal biventricular output and dimensions, reflected in reduced stroke distance and increased RV LV diameter ratios. The ratio of RV to LV dimensions in diastole appears to be a simple yet useful prognostic marker in CDH. Further validation of the prognostic utility of this simple Doppler measure in larger multicenter cohorts of neonates with CDH is warranted.