Right heart response to different loading conditions - a comparison of chronic volume versus pressure overload using an integrated echocardiographic and invasive approach
Authors: Botezatu BS , Enache R , Beladan CC , Radu DN , Calin A , Rosca M , Platon P , Predescu L , Popescu BA 
Published: February 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.
Background. It is widely believed that right ventricular (RV) volume overload is better tolerated than RV pressure overload and this is mainly due to the preservation of or even an increase in RV longitudinal function in patients (pts) with RV volume overload. Conversely, patients with RV pressure overload experience an early decrease in radial shortening and the global RV performance is maintained due to a normal longitudinal function. The multiparametric assessment of RV function and RV-pulmonary artery (PA) coupling could offer a better understanding of the RV adaptive mechanisms in response to volume versus pressure overload.
Purpose. To assess the right heart remodelling and function in different chronic loading conditions using an integrated echocardiographic and invasive approach.
Methods. Thirty-nine patients with atrial septal defect (ASD) and 41 pts with pulmonary hypertension (PH) age and gender-matched were enrolled. The etiology of PH was idiopathic (14 pts), operated congenital heart disease (3), connective tissue disease (9), chronic thromboembolic PH (8) and other forms of arterial PH (7). Clinical parameters, B-type natriuretic peptide (BNP), RV function and pulmonary artery stiffness (PAS) echocardiographic parameters were assessed. RV-PA coupling was assessed using the TAPSE to systolic PA pressure ratio. A right heart catheterization was also performed and ASD pts with pulmonary vascular resistance &gt;3 Wu and/or Qp/Qs ratio &lt;1.5 were excluded.
Results. PH pts were more symptomatic than pts with ASD (32 PH pts vs 6 ASD pts were in NYHA class III and IV, p &lt; 0.001). ASD pts had lower BNP levels (lnBNP 4.24 ± 1.11 vs 5.49 ± 1.29, p &lt; 0.001), similar right atrial (RA) area (26.6 ± 7.7 vs 27.8 ± 11.9 cm2, p = 0.61) and pressure (7.5 ± 4.2 vs 8.2 ± 5.9 mmHg), lower systolic (1.11 ± 0.13 vs 1.55 ± 0.50) and diastolic (1.21 ± 0.16 vs 1.50 ± 0.32) eccentricity index (p &lt; 0.001) and better RV function parameters than PH pts (all p &lt; 0.001): TAPSE (26 ± 5 vs 16 ± 3 mm), RV-free wall S wave (14.4 ± 2.5 vs 9.9 ± 2.1 cm/s), RV fractional area change (46 ± 8 vs 32 ± 8%), RV global longitudinal strain on 3 segments (-27.6 ± 5.0 vs -14.4 ± 6.0%) or 6 segments (-24.2 ± 4.3 vs -12.5 ± 4.9%). Also, ASD pts had less impaired PAS parameters (pulmonary compliance 4.03 ± 5.54 vs 1.53 ± 3.01 mm2/mmHg, p = 0.016; elastic modulus 167 ± 131 vs 594 ± 369 mmHg, p &lt; 0.001; beta index 5.36 ± 3.77 vs 11.00 ± 6.39, p &lt; 0.001) and better RV-PA coupling (0.60 ± 0.20 vs 0.19 ± 0.06 mm/mmHg, p &lt; 0.001) than PH pts. The BNP levels significantly correlated with RA area, parameters of RV size and systolic function and RV-PA coupling in both groups, but invasively assessed PA pressure correlated with BNP levels only in ASD pts.

Conclusions
Patients with ASD as a model of chronic RV volume overload have not only preserved RV longitudinal function but also better global RV function, PAS and RV-PA coupling compared to pts with chronic RV pressure overload. The BNP levels are significantly more impaired in pts with chronic RV pressure overload.