Accelerated idioventricular rhythm

The arrhythmias mainly observed are ventricular tachycardias, ventricular premature depolarizations and accelerated idioventricular rhythms as well as atrioventricular dissociation. 

Ventricular extra beats, including coupled beats (that is ventricular bigeminy), are the most common cardiac effects of digitalis toxicity, although they are not specific. In more severe cases ventricular tachycardia, bidirectional tachycardia, and ventricular fibrillation can occur. There have also been reports of accelerated idioventricular rhythm (41,42). 

Castellanos A, Shin EK, Luceri RM, Myerburg RJ. Parasystolic accelerated idioventricular rhythms producing bidirectional tachycardia patterns. J Electrophysiol 1988 2 296. 

VL and a mild ST-segment depression in lead I. (B) After 3 hours from fibrinolytic treatment ST segment is practically normal and accelerated idioventricular rhythm appears. In lead III a sinus complex, a fusion complex and a premature ventricular complex are shown. Lower part displays salvos of accelerated idioventricular rhythm in V1-V2 leads. 

Need to differentiate accelerated junctional rhythm from accelerated idioventricular rhythm (a possibly life-threatening arrhythmia)... 

Antiarrhythmic drugs (such as amiodarone, lidocaine) contraindicated for accelerated idioventricular rhythm because of possible suppression of escape beats... 

Is a reperfusion arrhythmia commonly seen after a Myocardial Infarction (MI). Idioventricular rhythm acts as a ventricular escape rhythm, with the dominant pacemaker originating from the ventricles. This rhythm protects the heart from asystole. It can be identified on the ECG by the wide strangely shaped QRS complexes with the absence of P waves (Fig. 6.38). The rate in Idioventricular rhythm is usually between 20 and 40 BPM. Idioventricular rhythm with a rate above this is termed accelerated Idioventricular rhythm. 

May be difficult to distinguish from accelerated idioventricular rhythm. 

Accelerated junctional rhythm and an accelerated Idioventricular rhythm appear similar but have different causes. To distinguish between them, closely examine the duration of the QRS complex, and then look for P waves. 

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