Unusual Midventricular LV Obstruction With Flow Aimed to the Apex Due to Apical RV Pacing: Elimination by Sequential Septo-Apical RV Pacing.

We report the case of an 88-year-old man who developed a mid-left-ventricular (LV) obstruction caused by apical pacing to manage third-degree atrioventricular block. The flow generated by the obstruction was directed toward 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 using a second right-ventricular mid-septally attached electrode combined with a sequential septo-apical pacing (septal stimulation 40 ms before apical pacing).