Atrial flutter is caused by an aberrant macro-circuit within the right atrium which cycles at 300bpm.

This circuit activates the AV node but because this node has a relatively long refractory period it is not able to conduct impulses down the His-Purkinje system at such a fast rate.

Instead the there is a degree of block meaning that only 2:1, 3:1, 4:1 or rarely 5:1 atrial impulses is conducted to the ventricle.

Causes

Causes are similar to atrial fibrillation (AF) but are more likely to occur with pulmonary disease such as:

• COPD
• Obstructive sleep apnoea
• Pulmonary emboli
• Pulmonary hypertension

Other causes include:

• Ischaemic heart disease
• Sepsis
• Alcohol
• Cardiomyopathy
• Thyrotoxicosis

PC

• Asymptomatic
• Palpitations