Validation of double-spike electrograms as markers of conduction delay or block in atrial flutter

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Arrhythmias

Background:

• Fragmented electrograms, often with double spikes, are common in atrial flutter, particularly in the right atrium's posterior walls.
• The clinical significance of these double-spike electrograms in relation to conduction abnormalities remains to be fully elucidated.

Purpose of the Study:

• To investigate double-spike electrograms as potential markers of localized conduction delay in common atrial flutter.
• To assess the impact of atrial overdrive pacing on double-spike electrogram characteristics.

Main Methods:

• Bipolar electrograms were recorded during atrial overdrive pacing in patients with common atrial flutter.
• Pacing was performed from the right atrium and the proximal coronary sinus.
• Changes in double-spike separation and electrogram sequence were analyzed.

Main Results:

• Coronary sinus pacing showed minimal changes in double-spike separation in most patients.
• Right atrial pacing significantly decreased double-spike separation, suggesting electrogram fusion.
• These findings indicate that double spikes may represent activation across a conduction delay zone.

Conclusions:

• Double-spike electrograms in atrial flutter likely represent activation on either side of a conduction delay.
• Pacing-induced changes support the presence of counterclockwise flutter circuits in the posterior right atrial wall.