**Atrial Flutter — Diagnosis, Management and Treatment**

Shameer Ahmed, Andrew Claughton and Paul A. Gould

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/60700

#### **Abstract**

Atrial flutter and atrial fibrillation are the two most common arrhythmias which originate in the atrium and cause a narrow complex tachycardia which has throm‐ boembolic risk and coexist clinically. Atrial flutter has been traditionally defined as a supraventricular arrhythmia with an atrial rate of 240–360 beats per minute (bpm). It is due to a macro-reentrant atrial activation around an anatomical barrier. Atrial flutter can be described as typical and atypical. Due to recent innovations in technology, catheter ablation has emerged as the most viable option with a success rate of more than 90 %. Three-dimensional electroanatomical mapping is useful in the treatment of atypical atrial flutter.

**Keywords:** Typical atrial flutter, Atypical atrial flutter, Cavo-tricuspid isthmus (CTI), Radio-frequency ablation (RFA), Differential pacing, Bidirectional block, Mapping, Entrainment

#### **1. Introduction**

Atrial arrhythmias are significant contributors for cardiac co-morbidity especially for stroke, heart failure and recurrent hospitalisations. The more frequent clinically encountered atrial tachyarrhythmias include atrial tachycardia, atrial flutter and atrial fibrillation. Although they are supraventricular in origin, apart from atrial tachycardia, they are not generally included in the nomenclature of supraventricular tachycardia. Atrial flutter has been traditionally defined as a macro-reentrant arrhythmia around a macroscopic (more than 2 cm in area)

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anatomical barrier that is confined within the atria. The atrial rate in atrial flutter is approxi‐ mately 240–360 beats per minute (bpm) with no distinct isoelectric period between the flutter 'F' waves. It is generally paroxysmal in nature in a structurally healthy heart. If the tachycardia persists for a prolonged period, it frequently can degenerate into atrial fibrillation, particularly if the patient already has structural heart disease. As such, atrial flutter and atrial fibrillation often coexist.

Atrial tachycardia is typically characterised by atrial rates >100 bpm but less than 240 bpm with discrete activation sequences and non-sinus P waves including a baseline isoelectric period between these waves on ECG. Its mechanism can be due to triggered activity or increased automaticity of atrial cells. These mechanisms are distinct from that of atrial flutter which is macro-reentrant; however, atrial tachycardia can also be re-entrant in mechanism similar to atrial flutter but on a microscopic level (re-entry around barriers of less than 2 cm).

Atrial fibrillation is due to fibrillatory waves in the atria with rates that are typically greater than 300 bpm in the atria. Currently these waves are considered chaotic and do not behave like the macro-reentry wavefront of atrial flutter. Re-entry however is still thought to play a role in atrial fibrillation, but its exact involvement is unknown.

In this chapter, we will discuss the classification, pathophysiology, clinical presentation, electrocardiographic characteristics, electrophysiological testing and both the pharmacologi‐ cal and ablative management of atrial flutter.
