Controlled Right Ventricular Pressure Overload Can Rescue Left Ventricular Dysfunction by Promoting Biventricular Adaptive Hypertrophy

Pulmonary artery banding (PAB) has been investigated as a therapy for left ventricular (LV) dysfunction in pediatric dilated cardiomyopathy; however, the underlying mechanisms of action of PAB-induced LV rehabilitation remain unknown. This study aims to establish a small animal model of PAB-treated LV dysfunction to document the biventricular hemodynamic and tissue-level modifications promoted by PAB. Sprague-Dawley rats underwent left anterior descending (LAD) artery ligation (LV dysfunction model) followed by PAB 1-week post-injury (LAD + PAB, n = 13). Controls consisted of sham (n = 16), PAB-only (n = 16), and LAD rats (n = 15). The animals underwent weekly echocardiography and terminal histopathology 4 weeks after surgery. Data shown as mean ± SEM or median (Q1-Q3). LAD + PAB rats exhibited positive LV remodeling (LV end-diastolic volume: 0.49 ± 0.02 mL vs 0.66 ± 0.03 mL; P < 0.001), improvement of LV ejection fraction (0.48 ± 0.01 vs. 0.36 ± 0.01; P < 0.001), and normalization of mitral valve Doppler E/A (1.43 ± 0.03 vs 1.91 ± 0.09; P < 0.001) compared to LAD animals. Histologic analysis documented LV hypertrophy (wall thickness/body weight: 9.3 ± 0.4 μm/g vs 7.2 ± 0.3 μm/g; P = 0.005), increased LV cardiomyocyte diameter (14.8 [Q1-Q3: 13.9-15.7] μm vs 11.3 [Q1-Q3: 10.8-11.7] μm; P = 0.001), and augmented neoangiogenesis (6.5 ± 0.2 vessels/mm² vs 4.7 ± 0.5 vessels/mm²; P = 0.005) in LAD + PAB vs LAD hearts. Mechanistically, we observed reduced LV fibrosis (9.8% [Q1-Q3: 7.7%-13.4%] vs 17.4% [Q1-Q3: 14.8%-20.2%]; P = 0.003) and fibroblast cellular senescence (5.7% [Q1-Q3: 4%-10.7%] vs 16.1% [7.6%-18.4%], P = 0.029), and preserved phospholamban (PLN) phosphorylation in the LV of LAD + PAB vs LAD rats (increased PLN/PLN: 0.6 ± 0.1 vs 1.0 ± 0.1; P = 0.008). In our model, PAB induced positive LV remodeling and improved LV systolic-diastolic function. PAB stimulated biventricular compensated hypertrophy that may constitute a potential adaptive mechanism which can rescue residual LV function and limit LV fibrosis/injury.