How does the cardiac impulse pass from the sinus to the atrioventricular node?

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Anatomy

Background:

• Historical context of cardiac conduction system discovery, including Tawara's atrioventricular bundle and Keith/Flack's sinus node.
• The 1910 German Pathological Society meeting consensus against specialized atrial pathways.
• Continued depiction of unproven specialized atrial pathways in cardiological literature.

Purpose of the Study:

• To critically review the evidence for specialized atrial conducting pathways.
• To present an alternative explanation for interatrial conduction.
• To address the discrepancy between historical findings and current representations of atrial anatomy.

Main Methods:

• Literature review and critical analysis of historical and contemporary studies on atrial conduction.
• Examination of evidence presented for and against specialized atrial pathways.
• Synthesis of findings to propose a mechanism for anisotropic interatrial conduction.

Main Results:

• No empirical evidence supports the existence of distinct, insulated pathways within the atrial walls.
• The aggregation of working atrial cardiomyocytes explains preferential anisotropic interatrial conduction.
• Historical criteria for recognizing specialized pathways have not been met by subsequent proposals.

Conclusions:

• The concept of specialized atrial pathways lacks robust scientific support.
• Anisotropic conduction through working atrial cardiomyocytes is the likely mechanism for interatrial impulse spread.
• Current anatomical representations of atrial conduction require re-evaluation based on available evidence.