Computational study on the cardiovascular system: Ventricular-ventricular interaction and right ventricular failure in pulmonary arterial hypertension

In this chapter, we describe how the CircAdapt model of the heart and circulation has been used to both increase our understanding of the pathophysiology of pulmonary arterial hypertension (PAH) and predict the effects of therapy. Simulation results reproduce key features of mechanical incoordination observed in PAH patients, including early diastolic septal motion and strain abnormalities. Our simulations suggest that septal movement is not dependent solely on the transseptal pressure gradient. Additionally, an imbalance of forces at the right ventricular (RV) attachment points resulting from ongoing RV free wall contraction during the early diastolic phase causes abnormal septal motion. We also demonstrate that atrial septostomy in patients with severe PAH might be beneficial because it increases left ventricular (LV) preload and, consequently, allows better maintenance of systemic arterial blood pressure during exercise. Finally, we show that pacing the RV free wall in severely decompensated PAH results in more synchronous LV and RV pressure decay, more homogeneous distribution of myofiber load over the ventricular walls, and a slight improvement of RV pump function.