ASSESSMENT OF LEFT VENTRICULAR ELECTROMECHANICAL ACTIVATION DURING RIGHT VENTRICULAR APICAL AND SEPTAL PACING

Abstract

Right ventricular apical pacing, inducing asynchronous ventricular contraction, may impair cardiac function. Alternative sites of pacing particularly high septum may have more favorable hemodynamic profile, physiological LV activation and normal ventricular contraction pattern. Aim of study: To find out alternative sites to RV apex for permanent pacemaker lead fixation which minimize LV dyssynchrony and subsequent complications. Patients and methods: The study involved 86 patients; 43 patients with active pacemaker lead fixation in site which achieved narrowest intra-cardiac QRS duration named as group 1(case group) and 43 patients with active pacemaker lead fixation in RV apex named as group 2(control group). Echocardiography and six minute walk test were done for patients of both groups. Results: high septal pacing was site which achieved the narrowest intra-cardiac QRS duration (100.27 ± 16.762 ms) when guided fluoroscopically and electrically and resulted into narrowest QRS duration on surface ECG (117.44 ± 7.89ms) when compared with RV apex (138.72± 12.77ms) (p <0.001). RV apical pacing resulted into marked electromechanical delay and LV dyssynchrony evident by increase in IVMD (50.83 ± 15.59 ms), LVPEP (189.34 ± 36.14 ms), RVPEP (139.27 ± 24.58 ms) and SPWMD (121.13 ± 33.70 ms) in RV apex in comparison to other right ventricular sites where IVMD (27.86 ± 15.06 ms), LVPEP (105.39 ± 44.48 ms), RVPEP (77.79 ± 33.21 ms) and SPWMD (75.2195 ± 37.36 ms) (p < 0.001). Tissue Doppler Imaging revealed marked difference on the opposing LV segments mainly between mid septal and mid lateral in group 2 cases. EF decreased in both groups after 3 months of permanent pacemaker implantation but the decrease was more significant in group 2 (59.67 ± 6.38) in comparison to group 1 (60.46 ± 6.36) (p < 0.001). Six minute walk test was better in group 1 patients (458.95 ± 230.20 m) than group 2 patients (325.11± 224.49 m) (p <0.001). Conclusion: High septum is the ideal site for permanent pacemaker implantation especially when guided fluoroscopically and electrically by intra-cardiac catheter. Compared with RV apical pacing, it is associated with improvement in functional and hemodynamic parameters over long-term follow-up.