Abstract 14877: Biventricular Structural And Functional Responses To Aortic Constriction In A Rabbit Model Of Chronic Right Ventricular Pressure Overload
Introduction: Chronic right ventricular (RV) pressure overload may result in diminished RV function. Aortic constriction may improve RV function in acute right heart failure by harnessing beneficial interventricular crosstalk. We investigated the effect of aortic constriction on biventricular structure and functional responses in an experimental model of chronic RV pressure overload.
Methods: An adjustable banding device was placed on the main pulmonary artery via lateral thoracotomy in adult rabbits (3.5-5 kg) (PA-group; n=9). An additional banding device was placed around the descending aorta (PA/AO-group; n=9). Sham operation was performed in 5 rabbits. Banding adjustments were performed on a weekly basis, in order to generate systemic or suprasystemic RV pressure at 28 days. The effects on the functional performance of both ventricles were assessed 5 weeks after surgery by pressure-volume loop-analysis using a conductance-catheter technique followed by histologic (Sirius Red and Masson's trichrome Staining) and molecular assessment (Real-time PCR) of left ventricle (LV) and RV myocardium.
Results: Contractile performance as indicated by the slope of the endsystolic pressure-volume relation (ESPVR) and preload recruitable stroke work (PRSW) were significantly higher in the PA/AO group for the LV (LVESPVR 18.2 vs. 11.3 mmHg/ml; p<0.05, LVPRSW 22.6 vs. 12.4; p<0.05) and for the RV (RVESPVR 13.9 vs. 7.7 mmHg/ml; p<0.05; RVPRSW 13.6 vs. 4.1; p<0.05) reflecting an improved biventricular contractility. As a consequence of chronic pressure overload, expression of Endothelin-1 was significantly increased in the PA and the PA/AO group (p<0.05 for the RV, p<0.01 for the LV compared to sham group). Improved systolic ventricular function was associated with significantly decreased TGF-ß expression in both ventricles within the PA/AO group (p<0.05) as well as decreased collagen and elastin content (p<0.05).
Conclusions: Aortic constriction in an experimental model of chronic RV pressure overload not only resulted in improved biventricular systolic function but also improved myocardial remodeling. This more physiologic hypertrophic response was associated with reduced expression of TGF-ß, and decreased LV and RV collagen and elastin content.
- © 2011 by American Heart Association, Inc.