Atrial flutter is a supraventricular tachycardic arrhythmia that tends to occur in individuals of an advanced age, although it is linked to endurance sports, also.
In cases of atrial flutter, the normal conduction pathway of the heart from the Sinoatrial node, through the atrioventricular node to the ventricles, is interrupted causing a re-entry pathway. This pathway can be the result of scarring after surgery or idiopathic, so of unknown origin.
The size of the right atrium directly corresponds to the length of the re-entry pathway, and the resulting atrial rate is somewhere between 200-400bpm, but most commonly 300.
This rate can be slower with:
- Class Ia (Fast Na channel blockers)
- Quinidine
- Procainamide
- Disopyramide
- Class 1c (Fast Na channel blockers)
- Flecainide
- Propaferone
- Class III (K channel blockers)
- Amiodarone
- Sotalol
- Ibutilide
- Dofetilide
P waves are still present on the patient ECG, but will display a “saw-tooth” pattern know as F waves.
The rate at which the ventricles contract is dictated by the eventual atrioventricular node conduction.
These degrees of AV block are referred to by way of a ratio of P waves and QRS complexes, the most common being 2:1 or 4:1.
In essence, a 2:1 block implies that the ventricular rate is half that of the atrial rate, so a 4:1 rate would be a quarter.
Type 1
Anti-clockwise re-entry atrial flutter accounts for around 90% of presentations and exhibits:
- + flutter waves
- V1
- – flutter waves
- II, III, aVF
Clockwise re-entry flutter is less common, and produces:
- Wide, – flutter waves
- V1
- + flutter waves
- II, III, aVF
Type 2 atrial flutter is less common and atrial rate can reach up to 450bpm.
The QRS presentation will normally be a narrow complex and areas of the trace will have no isoelectric baseline.
The fixed AV block ratio, 2:1, 4:1, etc may not always present. Varying degrees of block can appear on one recording i.e 2:1 and 3:1. Ensure to scrutinise the trace so as not to confuse flutter with fibrillation.
Treatment
The aim when treating atrial flutter is to return the patient’s rhythm to one of a sinus nature. This can be achieved via:
- Ablation
- This is less successful in type 2 flutter cases
- Electric cardioversion
- Pharmacological cardioversion
- Pacing
Ref:
lifeinthefastlane
Topol, E., Califf, R., Prystowsky, E., Thomas, J., Thompson., (2007) Textbook of Cardiovascular Medicine. 3rd Ed. Philedelphia: Lippincott Williams and Wilkins
The Student Physiologist 