Unusual midventricular LV obstruction with flow aimed to the apex due to apical RV pacing: elimination by sequential septo-apical RV pacing.

Abstract We report the case of an 88-year-old male who developed a mid-left ventricular (LV) obstruction due to apical pacing to manage third-degree atrio-ventricular block. The flow generated by the obstruction was directed towards the LV apex and appeared from late systole to early diastole. The obstruction appeared to result from earlier contraction at the apex compared with the midventricular portion of the LV, which was followed by an also earlier apical relaxation. The obstruction was eliminated by utilizing a second right ventricular mid-septally attached electrode combined with a sequential septo-apical pacing (septal stimulation 40 ms before apical pacing).