Accelerated idioventricular rhythm
|Accelerated idioventricular rhythm|
|Classification and external resources|
Accelerated idioventricular rhythm (AIVR) at a rate of 55/min presumably originating from the left ventricle (LV). Note the typical QRS morphology in lead V1 characteristic of ventricular ectopy from the LV. Monophasic R-wave with smooth upstroke and notching on the downstroke (i.e., the so-called taller left peak or "rabbit-ear".)
In accelerated idioventricular rhythm (AIVR), the rate of cardiac contraction is determined by the intrinsic rate of depolarization of the cardiac cells.
It can be present at birth.
In normal hearts the sinoatrial node in the atria depolarizes at a rate of 60-100 beats per minute as an effect of the parasympathetic autonomic nervous system (otherwise the SA node would depolarize at a rate of 100 beats per minute). This suppresses the intrinsic depolarization of the other parts of the heart.
The accelerated idioventricular rhythm occurs when depolarization rate of a normally suppressed focus increases to above that of the "higher order" focuses (the sinoatrial node and the atrioventricular node). This most commonly occurs in the setting of a sinus bradycardia.
Accelerated idioventricular rhythm is also the most common reperfusion arrhythmia in humans. However, ventricular tachycardia and ventricular fibrillation remain the most important causes of sudden death following spontaneous restoration of antegrade flow. 
AIVR appears similar to ventricular tachycardia but is benign and doesn't need any treatment. It can most easily be distinguished from VT in that the rate is less than 120 and usually less than 100 bpm.
- Freire G, Dubrow I (March 2008). "Accelerated idioventricular rhythm in newborns: a worrisome but benign entity with or without congenital heart disease". Pediatr Cardiol 29 (2): 457–62. doi:10.1007/s00246-007-9024-z. PMID 17687587.
- "Accelerated Idioventricular Rhythm: Overview - eMedicine". Retrieved 2008-12-21.
- AL Moens, MJ Claeys, JP Timmermans, CJ Vrints. Myocardial ischemia/reperfusion-injury, a clinical view on a complex pathophysiological process. International Journal of Cardiology 2005;100:179
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