Pulmonary artery blood flow dynamics in patients with chronic thromboembolic pulmonary hypertension; Analysis by computational fluid dynamics

Abstract

Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is a progressive disease with poor prognosis. The progression mechanisms of CTEPH have not been well-understood. Balloon pulmonary angioplasty (BPA) has been spread for the treatment of inoperable CTEPH. However, the efficacy of BPA for pulmonary blood flow dynamics is still unclear. Methods: We analyzed blood flow dynamics of pulmonary arteries using computational fluid dynamics (CFD) with 4 normal patients and 4 CTEPH patients before and after BPA. Results: In the patients with CTEPH, flow velocity and wall shear stress (WSS) in pulmonary arteries were significantly decreased compared with normal subjects. The blood flow velocity and WSS were significantly increased after BPA treatment (Fig.1). Although stagnation area of blood flow was widely observed in pulmonary artery of CTEPH patients, this area was significantly reduced after BPA (Fig.2). BPA treatment significantly increased the WSS at the distal portion of pulmonary artery and the vessel diameter also increased significantly (Fig.3). Conclusion: In the analysis using CFD, it seems that stagnation of blood flow plays a crucial role in the progression of CTEPH. BPA improved the stagnation of blood flow and WSS. Recovery of pulmonary blood flow dynamics might decrease thrombogenicity and lead to vascular endothelial function recovery.