The Bachmann bundle and interatrial conduction: comparing atrial morphology to electrical activity.

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Anatomy

Background:

• The Bachmann bundle (BB) is a key interatrial muscular connection.
• Its macroscopic anatomy and electrophysiological properties were previously unlinked.
• Activation pattern variations were attributed to anatomical differences.

Purpose of the Study:

• To analyze diverse activation patterns of the Bachmann bundle.
• To correlate these wavefronts with epicardial morphological structures.
• To investigate anatomical variations in human cadaveric hearts.

Main Methods:

• High-resolution epicardial mapping of the BB in 185 patients during sinus rhythm.
• Macroscopic examination of the epicardial atrial musculature in 19 postmortem hearts.
• Evaluation of BB morphology and surrounding interatrial connections.

Main Results:

• Epicardial mapping revealed right-to-left BB activation in most patients.
• A significant portion showed wavefronts emerging/entering the middle of the BB.
• A newly identified posterosuperior bundle was consistently observed connecting to the BB.

Conclusions:

• Interatrial connections identified morphologically correlate with epicardial mapping pathways.
• The Bachmann bundle and the posterosuperior bundle are consistently present both morphologically and electrophysiologically.
• Anatomical variations explain observed differences in atrial activation patterns.