Idioventricular rhythm

It has been suggested that bupivacaine may be more cardiotoxic than other long-acting local anesthetics (eg, ropivacaine). This reflects the fact that bupivacaine-induced blockade of sodium channels is potentiated by the long action potential duration of cardiac cells compared with nerve fibers. The most common electrocardiographic finding in patients with bupivacaine intoxication is a slow idioventricular rhythm with broad QRS complexes and eventually electromechanical dissociation. 

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. 

Five patients with acute accidental poisoning with V. album rapidly developed nausea, vomiting, abdominal pain, hypotension, and bradycardia (26). In four cases the electrocardiogram showed sinus bradycardia and in one there was complete atrioventricular block with an ectopic atrial bradycardia and an intermittent idioventricular rhythm. Symptomatic treatment and/or atropine led to recovery within a few hours. 

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. 

Earlier small observational reports found some response to atropine in asystole or pulseless idioventricular rhythm but little evidence to suggest that long-term outcomes were altered. In a retrospective case-control study, Stueven and colleagues found a 14% (6 of 43) success rate with atropine compared with a 0% (0 of 41) rate... 

Important to differentiate junctional rhythm from idioventricular rhythm (a life-threatening arrhythmia)... 

Antiarrhythmic drugs (such as amiodarone, lidocaine) contraindicated for 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. 

A 16-ycar-old girl who had taken amitriptyline, orphenadrino and flurazepam was admitted deeply unconscious showing no response to painful stimuli. Her pupils were widely dilated, heart rate 120/minuto and systolic blood pressure was 80 mm Hg, Subsequently convulsive episodes occurred and an ECG showed idioventricular rhythm. Four hours later cardiac monitoring showed resumption of sinus rhythm. After 48 hours she was fully conscious and superficially well. On the third day she developed acute gastric dilatation (37 ). 

May be difficult to differentiate between junctional rhythm and idioventricular rhythm. 

Protects the heart from potentially life-threatening idioventricular rhythms. 

May be difficult to distinguish from accelerated idioventricular rhythm. 

Distinguishing accelerated junctional rhythm from an 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. 

Idioventricular rhythm 107 Ventricular tachycardia 111 Ventricular fibrillation 122 Asystole 128... 

The same ECG characteristics as idioventricular rhythm except for heart rate. 

Continuous idioventricular rhythm Markedly decreased cardiac output from slow ventricular rate and loss of atrial kick. 

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