A Feasible Approach for Direct His-Bundle Pacing Using a New Steerable Catheter to Facilitate Precise Lead Placement

Francesco Zanon, MD; Enrico Baracca, MD; Silvio Aggio, MD; Gianni Pastore, MD; Graziano Boaretto, BS; Paola Cardano, PhD; Tiziana Marotta, PhD; Gianluca Rigatelli, MD, FESC, FACC; Mariapaola Galasso, MD; Mauro Carraro, MD; Pietro Zonzin, MD

Disclosures

J Cardiovasc Electrophysiol. 2006;17(1):29-33. 

In This Article

Abstract and Introduction

Abstract

Introduction: Much clinical evidence has shown that right ventricular (RV) apical pacing is detrimental to left ventricular function. Preservation of the use of the His-Purkinje (H-P) system may be ideal in heart block that is restricted to the AV node, but may be of no benefit when H-P disease exists.
Aim: To investigate the feasibility of direct His-bundle pacing (DHBP) using a new system consisting of a steerable catheter and a new 4.1 F screw-in lead.
Method: Between May and December 2004, 26 patients (19 male, mean age: 77 ± 5 years) with a standard pacemaker (PM) indication and preserved His-bundle conduction were enrolled and DHBP was attempted.
Results: DHBP was achieved in 24 patients (92%); two patients were paced in the His area, but the paced QRS morphology and duration were different from the native QRS. The mean time for lead positioning was 19 ± 17 minutes, the mean fluoroscopy time was 11 ± 8 minutes, and the total procedure time (skin-to-skin including positioning of a quadripolar diagnostic catheter for His recording) was 75 ± 18 minutes. In DHBP pacing, the acute pacing threshold was 2.3 ± 1.0 V at a pulse duration of 0.5 msec, and the sensed potentials were 2.9 ± 2.0 mV. At a 3-month follow-up examination, the same QRS duration and morphology recorded on implantation were observed in all patients. The pacing threshold was 2.8 ± 1.4 V, and sensed potentials were 2.5 ± 1.8 mV; the sensing configuration was changed from bipolar to unipolar in 6 patients to resolve undersensing issues. No major complications were observed.
Conclusions: This feasibility study shows that DHBP can be accomplished with a new system consisting of a steerable catheter and an active fixation lead in 92% of the patients in whom it was attempted.

Introduction

Eighty years ago, Wiggers[1] pointed out the detrimental effects RV apical pacing in an animal model. Pacing for bradycardia began in the 1960s using leads positioned in the right ventricular apex. The apical position was chosen because it was easily accessible, lead position was stable, and dislodgment rates were low. For many years physicians and medical companies have focused on improving the software and hardware of the device, without taking into consideration the pacing site, despite clinical and experimental observations of the deleterious effect of apical pacing.[2,3,4] Recently, there has been an increased interest in evaluating the effects of desynchronization in failing hearts and in finding new pacing modes to resynchronize the ventricles.[5,6] Because pacing the left ventricle (LV) is sometimes challenging, interest in selective RV pacing sites close to the native conduction system is growing. Two areas are considered to be possible target sites: the right ventricular outflow tract (RVOT)[7,8] and the His-bundle. The latter has so far been regarded as the ideal site in patients with normal distal His conduction, owing to the possibility to mimic physiological activation patterns. As the traditional tools do not allow an easy approach to His-bundle pacing there are few clinical reports of this pacing mode in the literature.[9,10,11,12] The aim of our study was to investigate the feasibility of direct His-bundle pacing (DHBP) using a new lead-delivery system, designed for selective site pacing.

Study Population

Between May and December 2004, 26 patients (19 male, mean age: 77 ± 5 years) with class I ACC/AHA[13] pacemaker (PM) indications and conserved His-bundle conduction were identified as candidates for permanent DHBP. Preserved His-bundle conduction was defined as: (1) HV interval less than or equal to 60 msec (2) the total duration of the His-bundle deflection less than 30 msec.[14] Moreover, to test His-bundle conduction, we paced from the screw-in lead up to 150 beats per minute in an attempt to achieve 1:1 conduction from stimulus artifact to QRS.

Indications for pacemaker implantation were as follows: second-degree atrioventricular block (AVB) in 11 patients, paroxysmal third-degree AVB in 3 patients, sick sinus syndrome (SSS) in 7 patients, and permanent atrial fibrillation (AF) with slow ventricular rate in 5 patients. Six patients also had right bundle branch block. Before implantation, all subjects underwent baseline clinical and echocardiographic evaluation. The mean ejection fraction was 53 ± 9%. Seventeen subjects were affected by hypertensive cardiomyopathy, 8 by ischemic cardiomyopathy, and 1 by valvular cardiomyopathy. The study, which complied with the Declaration of Helsinki, was approved by the local Ethics Committee, and all patients gave their informed consent.

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