Clinical Studies Of Physiological Pacing - Pacing Site And Pacing Mode

Part Ⅰ Clinical Study of Right Ventricular Outflow Tract PacingBackground: Since the introduction of permanent pacing, the preferred site for ventricular stimulation has been almost exclusively the right ventricular apex (RVA); because RVA pacing provides lead stability and low capture thresholds. However, RVA pacing altered ventricular depolarization vector and increased ventricular asynchronous contraction, which resulted in deterioration of left ventricular function. Pacing from the right ventricular outflow tract (RVOT) may provide better performance of the heart because it has a almost normal ventricular activation and conduction sequence. However, previous studies have not obtained consistent results about RVOT pacing. The possible reasons for this might be difference in patient selection, exactly pacing position in RVOT and evaluation criteria. More studies need for further understanding of benefits of RVOT pacing.Objective: This study is aimed to compare the contraction synchrony and cardiac performance between RVA and RVOT pacing.Methods: Forty-two patients (mean age 63.5±10.4 years) without structural heart disease were studied. The patients were randomized into RVA group (n=14) and RVOT group (n=28). The operation time and ventricular threshold changes trend were collected to evaluate the feasibility of RVOT pacing. The ventricular synchrony was evaluated by QRS duration, PPEI-APEI and Ts-SD, while the cardiac performance was appraised by Tei index. According to the ventricular pacing site confirmed by 3D-echocardiography, the RVOT group was divided into RVS group (n=17) and RVFW group (n=11). Ventricular synchrony and cardiac performance were further evaluated by...