Morphology and rheology of pulmonary arteries: A relationship with right ventricular function in patients with pulmonary arterial hypertension associated with atrial septal defect?

Abstract

Qualitative and quantitative hemodynamic flow indexes have been related to right ventricular (RV) function in pulmonary arterial hypertension (PAH), using 4-dimensional flow cardiac magnetic resonance (4D-flow CMR). Little is known in PAH congenital heart disease population characterized by intracardiac shunting. A prospective bi-centric study was conducted in two French referral centers for PAH to assess RV function and anatomical and rheological parameters in the proximal pulmonary arteries (PA) in PAH associated with atrial septal defect (ASD). A multiparametric evaluation, including a complete hemodynamic catheterization and a 4D flow CMR, was performed in 24 patients (50 years [41–55]) with PAH-ASD, of whom 16 (66%) had a persistent left-to-right shunt. Patients were divided into two groups according to the presence ( n = 14) or absence ( n = 10) of RV dysfunction, defined as RV ejection fraction (RVEF) < 45%. Tricuspid annular excursion (TAPSE) was 21 mm [18–26] and RVEF was 37% [27–52]. Mean pulmonary artery pressure was 50 mmHg [39–59] and pulmonary vascular resistance was 8 Wood units [6–8] and 42% were in WHO/NYHA function class III or VI. RV function was correlated with RV-PA coupling (correlation coefficient = −0.91, P <0.0001), PA compliance (correlation coefficient = −0.40, P = 0.04), and PA stiffness index (correlation coefficient = 0.43, P = 0.03). Helicity and vorticity were correlated with PA area, but there was no significant relationship with RV function. Intrinsic parameters were more alterated in the group without RV dysfunction, characterized by a persistent left to right shunt, with a decreased tight PA compliance ( P = 0.01), decreased distensibility ( P = 0.01), decreased pulsatility index ( P = 0.06), increased β-stiffness index ( P = 0.01), and increased elastance ( P = 0.01). In patients with left-to-right shunt, barometric and volumetric overload aggravates proximal PA remodelling with increased PA dilatation and stiffness. Paradoxically, in patients with RV dysfunction, normally associated with end-stage of PAH and right-to-left shunt, this remodelling is significantly less considerable.