Accelerated idioventricular rhythm

Background

AIVR results when rate of an ectopic ventricular pacemaker exceeds sinus node. Usually benign,self limiting

Causes

1. Reperfusion phase of acute myocardial infarction (= most common cause)
2. Beta-sympathomimetics (isoprenaline or adrenaline)
3. Drug toxicity, especially digoxin, cocaine and volatile anaesthetics such as desflurane
4. Electrolyte abnormalities
5. Cardiomyopathy, congenital heart disease, myocarditis
6. Return of spontaneous circulation (ROSC) following cardiac arrest
7. Athletic heart

ECG features

1. Regular rhythm.
2. Rate 50-110 bpm.
3. Three or more ventricular complexes.
4. QRS complexes >120ms.
5. Fusion and capture beats.

Management

1. AIVR is a benign rhythm in most settings and does not usually require treatment.
2. Self limiting and resolves when sinus rate exceeds that of the ventricular foci.
3. Anti-arrhythmics may cause precipitous haemodynamic deterioration and should be avoided.
4. Treat the underlying cause: e.g. correct electrolytes, restore myocardial perfusion.
5. Patients with low-cardiac-output states (e.g. severe biventricular failure) may benefit from restoration of AV synchrony to restore atrial kick – in this case atropine may be trialled to increase sinus rate and AV conduction.

References

http://lifeinthefastlane.com/ecg-library/aivr/