Right ventricular plasticity in a porcine model of chronic pressure overload

Background: Ventricular-arterial coupling is a measure of the relationship between ventricular contractility and afterload. We sought to determine the relationship between ventricular-arterial coupling and right ventricular (RV) remodeling in a novel porcine model of progressive pulmonary hypertension (PH).

Methods: Chronic PH was induced in pigs by ligation of the left pulmonary artery (PA) followed by 5 weekly injections of cyanoacrylate to progressively obstruct the right lower lobe arteries (PH group, n = 10). At 6 weeks, 5 PH animals underwent reperfusion of the left lung through conduit anastomosis to decrease RV afterload, whereas 5 other animals received no treatment. Five sham-operated piglets were used as controls. RV function was assessed using echocardiography and conductance catheterization. RV gene expression of beta-myosin heavy chain (β-MHC) and B-type natriuretic peptide (BNP) were quantified by polymerase chain reaction.

Results: At 6 weeks, compared with controls, the PH group had higher mean PA pressure (32 ± 6 vs 14 ± 2 mm Hg, p < 0.01). The increase in RV elastance was insufficient to compensate for the increase in pulmonary arterial elastance in the PH group and altered ventricular-arterial coupling occurred (0.65 ± 0.16 vs 1.28 ± 0.14, p < 0.01). The degree of ventricular-arterial uncoupling was related to RV enlargement and systolic dysfunction. Ventricular-arterial uncoupling and increased RV mass index were associated with up-regulation of β-MHC and BNP expression.

Conclusions: Ventricular-arterial coupling is closely associated with ventricular remodeling and systolic function as well as contractile and BNP gene expression. Dynamic changes in myosin expression may determine RV work efficiency in PH.