Testing a new mechanism for left interventricular septal pacing: the transseptal route; a feasibility and safety study.

ABSTRACT

AIMS: To prove the feasibility and safety of left interventricular septal pacing. BACKGROUND: Right ventricular apical pacing is an established but haemodynamically less favourable pacing method compared with transvenous left ventricular pacing. Alternatively, we propose a simple septal screw-in lead for left interventricular septal pacing. METHODS: A pacemaker lead with a long insulated screw with the two distal windings forming an active tip was implanted from the right side of the interventricular septum to the subendocardial left side in six goats. A special guiding sheath enabled stable, easy, and swift implantation of the lead. The implantation was performed using fluoroscopy together with. normal and contrast echocardiography (via the long pre-shaped sheath) and electrocardiographic signals (His-bundle recordings in conjunction with atrial and ventricular intracardiac signals). The screw was also positioned at other locations along the free wall, and at the interventricular septum to assess possible adverse effects at other sites. RESULTS: An average of 2.2 +/- 1.5 positions per goat was attempted. No adverse effects were noticed during implantation or at necropsy. In two goats, the final position was at the junction of the right ventricular wall and the interventricular septum. Parameters at the final positions were as follows the pacing threshold was 1.3 +/- 1.0 V at 0.5 ms; the pacing impedance was 1022 +/- 463 omega at 4.8 V and 0.5 ms. R-wave amplitudes were 17.6 +/- 7.6 mV. CONCLUSION: Left interventricular septal pacing is feasible. In our study it was safely performed in six goats. The pacing threshold was low, and the stability of the lead system was good. Implantations in humans and animals and haemodynamic evaluations are needed to reveal the potential benefits of this new form of left interventricular septal pacing.