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Biatrial activation in isthmus-dependent atrial flutter
L M Rodriguez1, C Timmermans, A Nabar
1Department of Cardiology, Academic Hospital Maastricht, Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands. LM.Rodriguez@cardio.azm.nl
Circulation
|November 21, 2001
Summary
In isthmus-dependent atrial flutter (AFL), the electrical circuit is confined to the right atrium. The left atrium (LA) is activated passively, acting as a bystander to the flutter wave.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Anatomy
Background:
- Isthmus-dependent atrial flutter (AFL) is a common arrhythmia.
- Understanding interatrial connections and left atrial (LA) activation is crucial for AFL management.
Purpose of the Study:
- To determine the biatrial activation pattern in isthmus-dependent AFL.
- To elucidate functional interatrial connections and LA activation patterns.
Main Methods:
- Electroanatomic mapping system used for biatrial activation in 10 patients undergoing right atrial isthmus ablation for AFL.
- Analysis of counterclockwise (n=7) and clockwise (n=3) AFL circuits.
Main Results:
- The AFL circuit was peritricuspid, propagating slowly (0.5+/-0.2 m/s) through the isthmus.
- The left atrium (LA) was activated by two wavefronts with breakthroughs in the atrial septum, overlapping 50+/-16% of the AFL cycle.
- In counterclockwise AFL, LA activation was inferosuperior, synchronous with septal activation, and initiated by flutter wave exit from the isthmus.
Conclusions:
- The circuit of isthmus-dependent AFL is entirely within the right atrium.
- Left atrial (LA) activation is a bystander phenomenon.
- LA activation occurs via trans-septal conduction through the inferior coronary sinus-LA connection, Bachmann's bundle, and/or fossa ovalis.
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