Abstract 5927: Right Ventricular Pacing Improves Right Heart Function in Experimental Pulmonary Arterial Hypertension
Background: Right heart failure in pulmonary arterial hypertension (PH) is associated with mechanical ventricular dyssynchrony, which leads to impaired right ventricular (RV) function, and - by adverse diastolic interaction - to impaired LV function as well. However, therapies aiming to restore synchrony by pacing are currently not available.
Objective: To determine the acute effects of RV-pacing on ventricular dyssynchrony in PH.
Methods: Chronic PH with right heart failure was induced in rats by injection of monocrotaline (MCT; 80 mg/kg). To validate for PH-related ventricular dyssynchrony, rats (6 PH, 6 controls) were examined by cardiac magnetic resonance imaging (9.4 Tesla), twenty-three days after MCT or sham injection. In a second group (10 PH, 4 controls), the effects of RV-pacing were studied in detail, using Langendorff-perfused heart preparations.
Results: In PH, septum bulging was observed, coinciding with a reversal of the trans-septal pressure gradient, as observed in clinical PH. Compared to baseline, RV-pacing significantly improved RV systolic function (RV dP/dtmax), and markedly decreased PTIRVP>LVP, an index of adverse diastolic interaction (Figure⇓). RV-pacing was able to resynchronize time to RV and LV peak-pressure (time difference RV-LV, unpaced: 9.8±1.2 ms vs. paced: 1.7±2.0 ms, p<0.001). RV-pacing had no detrimental effects on LV function or coronary perfusion, and no LV pre-excitation occurred.
Conclusion: In experimental PH, RV-pacing improved RV systolic function and diminished adverse diastolic interaction, suggesting resynchronization therapy as a potential novel treatment for PH-related ventricular dyssynchrony.