Abstract
Potts shunt (PS) was suggested as palliation for patients with suprasystemic pulmonary arterial hypertension (PAH) and right ventricular (RV) failure. PS, however, can result in poorly understood mortality. Here, a patient-specific geometrical multiscale model of PAH physiology and PS is developed for a paediatric PAH patient with stent-based PS. In the model, 7.6mm-diameter PS produces near-equalisation of the aortic and PA pressures and Q_p/Q_s (oxygenated vs deoxygenated blood flow) ratio of 0.72 associated with a 16% decrease of left ventricular (LV) output and 18% increase of RV output. The flow from LV to aortic arch branches increases by 16%, while LV contribution to the lower body flow decreases by 29%. Total flow in the descending aorta (DAo) increases by 18% due to RV contribution through the PS with flow into the distal PA branches decreasing. PS induces 18% increase of RV work due to its larger stroke volume pumped against lower afterload. Nonetheless, larger RV work does not lead to increased RV end-diastolic volume. Three-dimensional flow assessment demonstrates the PS jet impinging with a high velocity and wall shear stress on the opposite DAo wall with the most of the shunt flow being diverted to the DAo. Increasing the PS diameter from 5mm up to 10mm results in a nearly linear increase in post-operative shunt flow and a nearly linear decrease in shunt pressure-drop. In conclusion, this model reasonably represents patient-specific haemodynamics pre- and post-creation of the PS, providing insights into physiology of this complex condition, and presents a predictive tool that could be useful for clinical decision-making regarding suitability for PS in PAH patients with drug-resistant suprasystemic PAH.
Highlights
Pulmonary arterial hypertension (PAH) is a rare disease in paediatric patients that is associated with significant morbidity and mortality
The goals of our study are: (i) to present a geometric multiscale model that is capable of representing relevant 3D anatomy and associated flow features in the case of suprasystemic Idiopathic pulmonary artery hypertension (iPAH) palliated with Potts shunt (PS); (ii) to demonstrate that this model can be tuned to a patient-specific case while reproducing pre- and post-operative clinically measured haemodynamic parameters with acceptable errors; (iii) to shed light on pre- and post-operative local and global haemodynamics dictated by model physics; (iv) to assess how PS diameter and length affect global and local haemodynamics; and (v) to build a ‘standalone lumped parameter model (LPM)’ model in the process and assess the extent to which it can reproduce the GMM output
Model parametrization is based on clinical data obtained in a paediatric patient with suprasystemic idiopathic PAH accompanied by right ventricle (RV) failure who received the stent-based PS
Summary
Pulmonary arterial hypertension (PAH) is a rare disease in paediatric patients that is associated with significant morbidity and mortality. In the majority of paediatric patients, PAH is idiopathic or associated with congenital heart disease (Ivy et al 2013). Idiopathic pulmonary artery hypertension (iPAH) is a rare, chronic disorder of the pulmonary vasculature characterised by cellular changes in the vascular walls, which cause progressive constriction, obstruction or obliteration of the small pulmonary vessels in the lungs, thereby increasing the resistance to pulmonary blood flow. The right ventricle (RV) progressively adapts to pump blood through the high-pressure pulmonary vasculature by developing hypertrophy and dilatation, eventually resulting in cardiac failure and death. In the settings of donor organ shortage, for children with progressive suprasystemic PAH presenting with an inadequate response to drug therapy and progressive RV failure, there is a need for alternative approaches to avoid further RV deterioration
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