MRI-derived regional pulmonary perfusion and cardiac function for monitoring patients with chronic thromboembolic pulmonary hypertension before and after pulmonary endarterectomy

Abstract

An established method for treatment of chronic thromboembolic pulmonary hypertension (CTEPH) is pulmonary endarterectomy (PEA). The aim of the study is to evaluate the surgical success after PEA by means of cardio-pulmonary MRI. 22 patients with CTEPH were examined at 1.5T with a dynamic contrast enhanced 3D-FLASH (TWIST) sequence before and 15±09days after PEA. Pulmonary blood flow (PBF), left(l), right(r) ventricular (RV) function and cardiac mass were determined. Mean pulmonary artery pressure (mPAP) was measured before and after PEA by right heart catheterization. Six minute walking distance (6MWD) test was performed before and 6 months after PEA. Regional PBF after PEA increased significantly in: total lung parenchyma +49% (p=0.0002) (cardiac output (CO) adjusted: +11.6% (p=0.1232)), r. upper lobe (UL) +35% (p=0.0289) (CO adjusted: -0.5% (p=0.6226)), middle lobe +61% (p=0.0014) (CO adjusted: +20% (p=0.0728)), r lower lobe (LL) +79% (p<0.0001) (CO adjusted: +36% (p=0.0124)), lUL +22% (p=0.0663) (CO adjusted: -11% (p=0.3955)) and lLL +59% (p<0.0001) (CO adjusted: +19% (p=0.0446)). After PEA ventricular mass index decreased by 20% (p<0.0001). RV function increased: RV end-diastolic volume -14% (p=0.0071), RV ejection fraction +33% (p<0.0001). Cardiac index increased by 31% (p=0.0002). Mean mPAP decreased significantly by 46% (p<0.0001). 6MWD increased by 34% (p=0.0157) 6 months after PEA. Improvement of PBF is observed predominantly in the lower lungs 2 weeks after PEA. Increased flow after PEA in bilateral upper lobes was proportional to increased CO in response to decreased pulmonary pressures.