Original ArticleRadiofrequency Ablation for Atrial Tachycardia and Atrial Flutter
Section snippets
Classification
Consensus groups from the European Society of Cardiology and the North American Society of Pacing and Electrophysiology have defined regular atrial tachycardia (AT) as either focal or macro-reentrant, classified according to electrophysiological mechanisms and anatomical structures [1]. Focal ATs are characterised by a focal origin with subsequent centrifugal spread, with a mechanism based in abnormal automaticity, triggered activity or micro re-entry [2]. Macro-reentrant ATs, by contrast,
Anatomy/Mapping
So-called typical atrial flutter accounts for 90% of macro-reentrant ATs and the re-entry circuit has been well defined. The tricuspid valve annulus stands as a fixed anatomic barrier to electrical conduction anterior to the circuit whilst the posterior barrier is formed by the crista terminalis and the Eustachian ridge [3], [4], [5]. No anatomic barrier has been identified between the termination of the Eustachian ridge at the ostium of the coronary sinus and the superomedial aspect of the
Other Macro-reentrant ATs
Macro-reentant ATs in which the circuit does not involve the CTI as a critical isthmus have often been grouped together and referred to as “atypical atrial flutter”, although a more accurate designation is “non-CTI dependent flutter”. These include re-entry circuits which develop around surgical scars following correction of valvular or congenital disease (lesional AT) [23], [24], circuits which develop following surgical or catheter ablation of atrial fibrillation, and circuits around areas of
Anatomy/Mechanisms
Focal AT is defined as activation from a discrete focus with subsequent centrifugal spread. Such focal activity may be due to abnormal automaticity, triggered activity or a micro-reentrant circuit. In general, abnormal automaticity is characterised by spontaneous atrial activity that is enhanced by isoprenaline but not induced by programmed extra-stimululi, whereas triggered activity and micro-reentry can both be initiated and terminated by programmed extra-stimuli. There is, however, much
Conclusions
Atrial tachycardia is a generic term for a range of differing circuits. These can be broadly divided by mechanism into macro-reentrant, focal and small circuit re-entry. “Atrial flutter” is a term which is today largely restricted to those classical circuits around the tricuspid annulus involving the cavo-tricuspid isthmus. The advent of sophisticated mapping solutions has rendered the vast majority of these atrial circuits curable with catheter ablation, with high success rates and very low
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