Computerized activation sequence mapping of the human atrial septum

Area of Science:

• Electrophysiology
• Cardiac Anatomy
• Arrhythmia Mechanisms

Background:

• The atrial septum's role in electrical activation and arrhythmias is not fully understood.
• Intraoperative mapping provides detailed insights into cardiac electrical pathways.

Purpose of the Study:

• To delineate electrical activation patterns in the atrial septum during sinus rhythm and various supraventricular tachycardias.
• To elucidate the atrial septum's involvement in arrhythmias like Wolff-Parkinson-White syndrome, AV node reentrant tachycardia, and atrial flutter.
• To provide a basis for surgical ablation strategies targeting these arrhythmias.

Main Methods:

• Intraoperative recording of atrial epicardial and septal electrograms using a 156-channel computerized mapping system.
• Simultaneous data acquisition from 156 atrial electrodes.
• Analysis and display of data as isochronous maps on a two-dimensional atrial diagram.

Main Results:

• During sinus rhythm, activation propagated fastest along atrial septal muscle bundles.
• In Wolff-Parkinson-White syndrome, earliest retrograde atrial activation sites correlated with septal pathway insertions.
• Atrial activation during AV node reentrant tachycardia indicated atrial tissue outside the AV node is crucial.
• Atrial flutter mapping suggested the atrial septum is a key component of the macroreentrant circuit.

Conclusions:

• The atrial septum plays a critical role in normal electrical conduction and various atrial arrhythmias.
• Mapping data supports specific surgical approaches for accessory pathways and AV node reentrant tachycardia.
• The atrial septum is integral to atrial flutter circuits, suggesting amenability to surgical control.