The relation between atrial fibrillation wavefront characteristics and accessory pathway conduction

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Anatomy

Background:

• The source-sink relationship for cardiac impulse propagation is established in vitro.
• Its in vivo relevance in humans, particularly concerning accessory pathways, remains unverified.

Purpose of the Study:

• To investigate the in vivo source-sink relationship in human accessory pathways.
• To analyze atrial wavefront characteristics preceding changes in impulse conduction through accessory pathways.

Main Methods:

• Studied eight patients undergoing accessory pathway division.
• Used a 56-channel bipolar electrode array over the atrioventricular groove.
• Electrically induced atrial fibrillation and analyzed 10 episodes of QRS transition.

Main Results:

• Preexcited QRS complexes correlated with uniform, large atrial wavefronts.
• Changes preceding conduction loss included secondary wavefront invasion, wavefront collision, wavefront fractionation, and wavefronts entering refractory periods.
• Local conduction block, wavefront curvature, and fractionation were observed.

Conclusions:

• Local atrial wavefront characteristics significantly influence impulse propagation through human accessory pathways.
• Wavefront collision, curvature, and fractionation precede loss of accessory pathway conduction.
• These findings support the source-sink relationship as a key determinant of impulse propagation safety in the human heart.