Bidirectional Ventricular Tachycardia

Bidirectional ventricular tachycardia is the classical arrhythmia of digoxin toxicity. Common observation is 180 degrees swing in frontal plane QRS axis with a basic right bundle branch block pattern. Alternate right and left bundle branch block patterns can also occur. Other causes of bidirectional ventricular tachycardia are aconite poisoning, myocarditis, myocardial infarction, metastatic cardiac tumour and sometimes hypokalemia. Two inherited cardiac channelopathies which can cause bidirectional ventricular tachycardia are catecholaminergic polymorphic ventricular tachycardia and Anderso-Tawil syndrome. It may be noted that epinephrine is contraindicated in catecholaminergic polymorphic ventricular tachycardia with cardiac arrest. Intravenous opioid and general anaesthesia are recommended instead.