Atrial flutter

Definition

Butterflies have wings. They can flutter like atria. Well, nothing like atria really. I like wings. And atria.

An atrial contraction rate of over 250-300 bpm.

Epidemiology

It's common. Probably.

Pathophysiology

There is a re-entrant circuit of excitation i.e. it goes straight back into the atria instead of the impulses just travellling to the ventricles. Ischaemic heart disease, hyperthyroidism, cardiomyopathy and rheumatic heart disease can all cause it but sometimes, no cause is found.

Clinical Features

• Palpitations
• Chest pain
• Shortness of breath

On examination

• Pulse
  • 125-160 bpm (at this rate, the ratio of impulses reaching the ventricle is about 2:1)
  • Regular usually, irregular in variable AV block
• 'A' waves in JVP exceeds the pulse rate
• Carotid compression may slow rate
• Signs of heart failure

Investigations

ECG

If you get 3:1 block (3 atrial contractions to 1 ventricular contractions), you'll get a saw-tooth appearance. In 2:1 block, P waves can be difficult to see. If uncertain, carotid sinus pressure can help to uncouple the atria and ventricles, revealing the P waves.

Seen most clearly in VI, II, III & aVF. It should always be considered in a patient with a regular rate of 150 bpm.

Bloods

• U+Es
• TFTs

Imaging

Echocardiography

Management

There's basically three things you can do: drugs, cardioversion or pacing.

Drugs

You use antiarrhythmics and the ones used are:

• Class Ia - Disopyramide
• Class Ic - Flecanide, Propafenone
• Class III - Sotalol

DC Cardioversion

Electric shock through the heart, like a more controlled version of defibrillation.

Pacing

This is essentially an implantable defibrillator. When your heart starts to flutter, it kicks in with a shock.