Abstract
BackgroundPediatric pulmonary hypertension (PH) remains a disease with high morbidity and mortality in children. Understanding ventricular-vascular coupling, a measure of how well matched the ventricular and vascular function are, may elucidate pathway leading to right heart failure. Ventricular vascular coupling ratio (VVCR), comprised of effective elastance (Ea, index of arterial load) and right ventricular maximal end-systolic elastance (Ees, index of contractility), is conventionally determined by catheterization. Here, we apply a non-invasive approach to determining VVCR in pediatric subjects with PH.MethodsThis retrospective study included PH subjects who had a cardiovascular magnetic resonance (CMR) study within 14 days of cardiac catheterization. PH was defined as mean pulmonary artery pressure (mPAP) ≥ 25 mmHg on prior or current catheterization. A non-invasive measure of VVCR was derived from CMR-only (VVCRm) and compared to VVCR estimated by catheterization-derived single beat estimation (VVCRs). Indexed pulmonary vascular resistance (PVRi) and pulmonary vascular reactivity were determined during the catheterization procedure. Pearson correlation coefficients were calculated between PVRi and VVCRm. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of VVCRm in predicting vascular reactivity.ResultsSeventeen subjects (3 months-23 years; mean 11.3 ± 7.4 years) were identified between January 2009-August 2013 for inclusion with equal gender distributions. Mean mPAP was 35 mmHg ± 15 and PVRi was 8.5 Woods unit x m2 ± 7.8. VVCRm (range 0.43–2.82) increased with increasing severity as defined by PVRi (p < 0.001), and was highly correlated with PVRi (r = 0.92, 95 % CI 0.79–0.97, p < 0.0001). Regression of VVCRm and PVRi demonstrated differing lines when separated by reactivity. VVCRm was significantly correlated with VVCRs (r = 0.79, CI 0.48–0.99, p <0.0001). ROC curve analysis showed high accuracy of VVCRm in determining vascular reactivity (VVCR = 0.85 had a sensitivity of 100 % and a specificity of 80 %) with an area under the curve of 0.89 (p = 0.008).ConclusionMeasurement of VVCRm in pediatrics is feasible. Pulmonary vascular non-reactivity may be contribute to ventricular-vascular decoupling in severe PH. Therapeutic intervention to maintain a low vascular afterload in reactive patients may preserve right ventricular functional reserve and delay the onset of RV-PA decoupling. Use of VVCRm may have significant prognostic implication.
Highlights
Pediatric pulmonary hypertension (PH) remains a disease with high morbidity and mortality in children
While there are some similarities between adult and pediatric pathophysiology [4], the disease may be more severe with worse survival in children [5,6,7]
Different from adult PH, the etiology of pediatric PH is mostly idiopathic pulmonary arterial hypertension and PH associated with congenital heart disease [1]
Summary
Pediatric pulmonary hypertension (PH) remains a disease with high morbidity and mortality in children. While there are some similarities between adult and pediatric pathophysiology [4], the disease may be more severe with worse survival in children [5,6,7]. This higher severity in youth is in due to differences in underlying causes, presence of congenital heart disease, effects of maturation, and differences in clinical symptoms leading to diagnosis in later stages [8]. Different from adult PH, the etiology of pediatric PH is mostly idiopathic pulmonary arterial hypertension and PH associated with congenital heart disease [1]. There has been increased interest in a more comprehensive understanding of the interaction of the RV and vasculature, and the role that this interaction plays in the pathophysiology of PH [9,10,11,12]
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