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.