Conduction system pacing is an alternative practice to conventional right ventricular apical pacing. It is a method that maintains physiologic ventricular activation, based on a correct pathophysiological basis, in which the pacing lead bypasses the lesion of the electrical fibers, and the electrical impulse transmits through the intact adjacent conduction system. For this reason, it might reasonably characterized by the term “electrical bypass” compared to the coronary artery bypass in revascularization therapy. In this review reference is made to the sequence of events that conventional right ventricular pacing may cause adverse outcomes. Furthermore, there is a reference to alternative strategies and pacing sites. Interest focuses on the modalities for which there is data from the literature, namely for the Right Ventricular (RV) septal pacing, the His Bunde pacing (HBP), and the Left Bundle Branch pacing (LBBP). A more extensive reference is about the HBP, for which there are the most updating data. We analyze the considerations that limit HBP wide application in three axes, and we also present the data for the implantation and follow-up of these patients. Then, the indications with their most important studies to date are described in detail, not only in their undoubtedly positive findings but also in their weak aspects, because of which, this pacing mode has not yet received a strong recommendation for implementation. Finally, there is a report on LBBP, focusing mainly on its points of differentiation from HBP.

Introduction: We sought to investigate the net effect of wide area circumferential radiofrequency catheter ablation (WACA) on the atrial (LA) geometry. Methods and results: Seventy-one patients, who underwent a second PVI procedure, after index procedure of point-by-point WACA, for recurrent paroxysmal (n=31) or persistent (n=40) atrial fibrillation (AF) in our center were included. A three-dimension rotational angiography of the left atrium (3D-RA) under rapid ventricular pacing was performed immediately before ablation, at index and repeat ablation in all patients. LA geometry in terms of volume, sphericity and surface were assessed in all patients between first and second PVI. There was a statistical significant reduction of the LA volume (65,6 ± 14 ml/m2 vs 62,2 ± 15 ml/m2, p<0,001) and of the surface of the LA (74,4 ± 11,2 vs 70,4 ± 11,2 cm2/m2, p<0,001), whereas the sphericity of the LA increased significantly (82 ± 2% vs. 83 ± 2%, p=0,004) in all 71 patients. Patients with paroxysmal AF showed significant decrease of the LA volume (121,8 ± 25,7 vs 116 ± 32 ml, p=0,008) and increase of the LA sphericity (82,3 ± 2,1 vs 83,1 ± 2%, p=0,009). Patients with persistent AF showed significant decrease of the LA volume (133,5 ± 32 vs 126 ± 32 ml, p=0,005), but only a trend towards increased sphericity (82,4 ± 2,8 vs 83 ± 2,4%, p=ns). Conlusions: WACA results into significant reduction of the LA volume, LA surface area and into significant increase of the LA sphericity in treated patients with recurrent AF.