Right ventricular systolic function and cardiac resynchronization therapy

Objectives: The aim of this study was to investigate the influence of right ventricular (RV) dysfunction on the response to cardiac resynchronization therapy (CRT) and the impact of CRT on RV function in a beagle model of heart failure (HF). Methods: Twenty-one beagles were implanted with transvenous cardiac pacemakers and underwent rapid RV pacing for 2 weeks at 260 bpm to induce HF. Dogs were subsequently divided into three groups that were either treated with bi-ventricular pacing (CRT group) or untreated (control group and HF group). Echocardiographic images were acquired at baseline, before CRT, and 4 weeks after CRT. Results: Left ventricular systolic function and synchrony (left ventricular internal dimensions, left ventricular end systolic volume [LVESV], left ventricular ejection fraction [LVEF], septal-to-posterior wall motion delay [SPWMD], and aorta pre-ejection interval and the pulmonary artery pre-ejection interval [|APEI-PPEI|]) were significantly improved in the CRT group compared with the HF group. RV myocardial performance index (MPI) and pulmonary artery systolic pressure deteriorated with left ventricular dysfunction and improved after CRT. RV outflow ESV, standard deviation of time to minimum systolic volume (Tmsv), and Tmsv% decreased in the CRT group compared with the HF group. LVESV, LVEF, SPWMD, and |APEI-PPEI| were significantly different between responders and nonresponders, while there was no difference about RV functional parameters. Conclusions: RV function deteriorated with left ventricular dysfunction and improved after CRT. RV function did not significantly influence the response to CRT.