  Reversed 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
Qp/Qs (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
nearly linear decrease in post-operative Qp/Qs ratio. 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 reversed PS in PAH patients with drug-resistant
suprasystemic PAH.

Medical Physics;Fluid Dynamics