Bachmann's bundle versus right atrial appendage capture

A simple method for Bachmann's bundle pacing with indigenous modification of J-stylet

Background

Pacing in the Bachmann's bundle (BB) area (upper atrial septum) appears superior to right atrial appendage or free wall stimulation for the prevention of paroxysmal atrial fibrillation in patients with atrial conduction delay. However, insertion of active fixation lead in the upper atrial septal position is difficult and time consuming with conventional stylet, inhibiting application of this pacing method in routine practice.

Methods

The technique of positioning the atrial lead in BB with hand-made stylet is presented with emphasis on electrocardiographic P-wave pattern and fluoroscopic landmarks.

Results

The results demonstrate an acute implantation and short-term success of BB pacing of 14 patients out of 15 patients without major complications. Pacing parameters at implantation and 3 months postprocedure were noted which were within normal limits.

Conclusion

These favorable initial results indicate that the positioning of active fixation atrial lead in BB with fluoroscopic landmarks is feasible and reproducible with a simple technique.

Effect of atrial lead position on atrial automatic capture verification

INTRODUCTION

Optimizing atrial automatic capture verification based on atrial-evoked response (AER) detection requires maximizing the signal artifact ratio (SAR), that is, AER to stimulation artifact (ART). This study evaluated the effect of bipolar atrial lead position on sensed AER, ART, and SAR.

METHODS AND RESULTS

A custom-made external research system (INSIGNIA(AC), Boston Scientific Corp. St Paul, MN, USA) was used to perform an automatic voltage step-down atrial pacing protocol at three different right atrial lead positions (A-appendage, L-lateral wall, and S-septal wall) in each studied patient. The atrial pacing and the AER sensing configurations were independent. The pacing was unipolar in an A(tip)-Can configuration while sensing was in A(ring)-I(ndiff). Data from 16 patients (mean age 71.1 +/- 9.6 years) and six-lead models from five different manufacturers were analyzed. Study results show that with all lead types, the atrial lead placement had no significant effect on AER(min), ART(max), and SAR(min) and only one patient had an SAR that was not sufficient to support successful automatic capture verification at all tested atrial pacing sites.

CONCLUSION

The atrial pacing site has minimal effect on AER sensing when using an independent pace/sense configuration. The leads placed at all tested sites were found to have the parameters sufficient to support the atrial automatic capture verification in all but one patient.

Bachmann's Bundle: Does It Play a Role in Atrial Fibrillation?

BACKGROUND

Cardiac anatomists have known the presence of a group of specialized fibers connecting the right and left atrium for years. However, only recently have clinical cardiologists come to recognize the potential importance of this specialized conduction system. Anatomical and microscopic studies have shown that the Bachmann's bundle (BB) represents a distinct structure similar to the atrio-ventricular node and the His-Purkinje conduction system but without any insulating tissue.

RESULTS

BB cells have specialized electrophysiological properties like supernormal excitability and faster longitudinal conduction that can facilitate more rapid impulse transmission compared to the normal atrial tissue. Experimental blockage of this pathway causes prolongation and widening of the P wave, which is associated with an increased incidence of atrial fibrillation. Atrial pacing is effective in reducing the incidence of atrial fibrillation by preventing bradycardia, synchronizing the atria, limiting anisotropy and reducing the dispersion of refractoriness. Various animal and human studies have shown pacing near the right atrial insertion of BB to have a beneficial effect in patients with interatrial conduction delay and atrial tachyarrhythmias. This mode of atrial septal pacing is convenient, safe, reliable, and clinically as effective as multisite pacing.

CONCLUSION

This article is an effort to define the special properties of BB and its possible role in prevention of atrial fibrillation by permanent pacemakers.