Objective: The objective of the study is to evaluate the intraventricular (LV) synchrony pattern in children with permanent pacemaker.

Methods: LV synchrony was evaluated in 40 children with complete heart block and life-time pacemaker dependency. Their median age was 7.2 years (range 0.1 – 18.0) and all has had a minimum of 1 year post pacemaker implantation follow-up. Nineteen had epicardial LV apical pacing, 13 had RV apical (8 epicardial and 5 endocardial) pacing and the remaining 8 had endocardial Septal pacing. The lead location was confirmed by x-ray and ECG imaging. Echocardiography and velocity vector imaging (VVI) were performed (Sequoia, Siemens Medical Solutions, Mountain View, CA) to evaluate the LV synchrony in all patients. Ten normal children were also evaluated as control.

Results: LV apical paced is superior to RV septal and RV apical paced children in term of LV synchrony. The mean intraventricular mechanical delay by short axis of LV apical, RV septal and RV apical pacing were 43 +/- 10 msec vs 47 +/- 13 msec vs 47 +/- 14 msec. Whilst the mean Septal to posterior wall motion delay were: 37 +/- 10 msec vs 43 +/- 8 msec vs 48 +/- 20 msec. The intraventricular mechanical delay by short axis and septal to posterior wall in control group were 30 +/- 10 msec and 29 +/- 10 msec respectively.

Conclusions: Epicardial LV apical pacing is superior to endocardial RV septal and RV apical pacing in terms of preservation of left ventricular synchrony.