A case of retractable helix lead auto-retraction: A possible cause of deep septal lead dislodgement

This paper explains the phenomenon where the helix lead automatically retracts because of residual torque during deep septal pacing.

A rare case of delayed complete lead dislodgement after deep septal pacing: A hidden risk of the specific procedure

Deep septal ventricular pacing is a recently developed physiological pacing modality with good efficacy; however, it has a potential risk of unusual complications. Here, we report a patient with pacing failure and spontaneous, complete lead dislodgement after >2 years of deep septal pacing, possibly caused by systemic bacterial infection and specific lead behavior in the septal myocardium. This case report may implicate a hidden risk of unusual complications in deep septal pacing.

ECG and Pacing Criteria for Differentiating Conduction System Pacing from Myocardial Pacing

During His-Purkinje conduction system (HPS) pacing, it is crucial to confirm capture of the His bundle or left bundle branch versus myocardialonly capture. For this, several methods and criteria for differentiation between non-selective (ns) capture - capture of the HPS and the adjacent myocardium - and myocardial-only capture were developed. HPS capture results in faster and more homogenous depolarisation of the left ventricle than right ventricular septal (RVS) myocardial-only capture. Specifically, the depolarisation of the left ventricle (LV) does not require slow cell-to-cell spread of activation from the right side to the left side of the interventricular septum but begins simultaneously with QRS onset as in native depolarisation. These phenomena greatly influence QRS complex morphology and form the basis of electrocardiographic differentiation between HPS and myocardial paced QRS. Moreover, the HPS and the working myocardium are different tissues within the heart muscle that vary not only in conduction velocities but also in refractoriness and capture thresholds. These last two differences can be exploited for the diagnosis of HPS capture using dynamic pacing manoeuvres, namely differential output pacing, programmed stimulation and burst pacing. This review summarises current knowledge of this subject.

His-Purkinje Conduction System Pacing: State of the Art in 2020

Conduction system pacing involves directly stimulating the specialised His-Purkinje cardiac conduction system with the aim of activating the ventricles physiologically, in contrast to the dyssynchronous activation produced by conventional myocardial pacing. Since the first report of permanent His bundle pacing (HBP) in 2000, the stylet-driven technique of its earliest incarnation has been superseded by a more successful stylet-less approach. Widespread uptake has led to a much greater evidence base. Single-centre observational studies have now been supported by large multicentre, international registries, mechanistic studies and the first randomised controlled trials. New evidence has elucidated mechanisms of HBP and illustrated the nature and magnitude of its potential benefits for preventing pacing-induced cardiomyopathy and correcting bundle branch block. Left bundle branch pacing (LBBP) is a newer technique in which the lead is fixed deep into the left side of the intraventricular septum to allow capture of the left bundle, distal to the His bundle. LBBP holds promise as a method for physiological pacing that overcomes some of the fixation, threshold and sensing challenges of HBP. In this state-of-the-art review of His-Purkinje conduction system pacing, the authors assess recent evidence and current practice and explore emerging and future directions in this rapidly evolving field.