Endocardial and epicardial activation maps for three-dimensional perimitral flutter using a three-dimensional mapping...

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Ablation

Background:

• Perimitral flutter (PMF) is a macro-reentrant tachycardia treated with mitral isthmus (MI) linear ablation.
• PMF can involve epicardial connections like the coronary sinus and vein of Marshall.
• Three-dimensional (3D) atrial tachycardia (AT) involving intramural tissue has not been previously reported.

Observation:

• A 78-year-old man with recurrent AT/PMF underwent multiple catheter ablations.
• Despite complete endocardial and epicardial MI block, AT persisted, suggesting an intramural conduction pathway.
• Activation mapping revealed a 3D-PMF circuit involving intramural muscle bundles not fully mapped by epicardial approaches.

Findings:

• Endocardial and epicardial mapping identified a 3D-PMF circuit utilizing intramural muscle and bundles.
• The tachycardia circuit's intramural component explained incomplete activation mapping.
• Successful ablation was achieved by targeting the mitral valve annulus where intramural bundles may attach.

Implications:

• This case highlights the existence of 3D-PMF involving intramural tissues.
• Recognizing and mapping intramural atrial tachycardia is essential for successful catheter ablation.
• Advanced mapping techniques may be required to fully elucidate complex tachycardia circuits.