Makindo Medical Notes

AIVR (Accelerated Idioventricular Rhythm) is a typically transient rhythm, rarely causing haemodynamic instability or requiring treatment. It occurs when the rate of an ectopic ventricular pacemaker causes a wide QRS rhythm that is faster than the sinus node but not fast enough to meet the tachycardia criteria.

About

• Commonly observed post-MI, resembling slow VT (Ventricular Tachycardia).
• Usually managed conservatively with patient monitoring.
• Typically a well-tolerated, benign, and self-limiting arrhythmia.
• Does not generally require treatment unless the patient is haemodynamically unstable.

ECG Characteristics

• Regular broad complex tachycardia with a rate of 40–120 beats per minute.
• Rates of 100–120 bpm may be misinterpreted as slow VT.

Differential Diagnosis

• Rates < 50 bpm: Consider complete heart block (CHB) and ventricular escape rhythm.
• Rates > 110 bpm: Consider slow ventricular tachycardia.
• Consider junctional rhythm with aberrancy as another potential differential diagnosis.

Causes

• Ischaemic heart disease.
• STEMI, often associated with reperfusion (e.g., PCI or thrombolysis).
• Cocaine use, cardiomyopathy.
• Myocarditis, digoxin toxicity (check levels and correct hypokalaemia).
• Normal athletic hearts, particularly in well-trained individuals.
• During ROSC (Return of Spontaneous Circulation) after a cardiac arrest.

Clinical Presentation

• Variable heart sound intensity and cannon A waves, due to AV dissociation.
• Occurs in the setting of acute STEMI with usual associated complications.

Management

• Observation is typically the standard approach. AIVR is benign in most cases and does not usually require treatment as long as blood pressure and clinical condition remain stable.
• AIVR typically self-limits and resolves when the sinus frequency exceeds that of the ventricular pacemaker.
• In the context of myocardial infarction (MI), AIVR often indicates reperfusion and generally requires no intervention.
• Seek senior advice before administering any treatment. Inappropriate use of IV Lidocaine or Amiodarone can cause conduction issues or even result in asystole.

References

• Accelerated Idioventricular Rhythm (AIVR) - LITFL
• Idioventricular Rhythm - NCBI Bookshelf