Variant Form of Bidirectional Ventricular Tachycardia

Report:

Bidirectional ventricular tachycardia 140/min

Comment:

The tachycardia is bidirectional in lead 2 and merely alternating in several other leads. It was a direct descendant of a monomorphic VT (not shown); its other parent may have been 80 mg of sotalol. Its LBBB morphology is unusual for bidirectional VT – vast majority of which look like RBBB with alternating hemiblocks in the frontal plane55. Here the axis swing in the frontal plane is only between left and normal. Vast majority of bidirectional VTs are also due to digitalis toxicity; this one is not.

Although the patient was digitalised, the level was in low-therapeutic range. It is most unlikely that he was digoxin-toxic. The BP fell after sotalol and he was cardioverted by a 150 Joule countershock. Had I thought he was digoxin-toxic I would have tried overdrive pacing, magnesium, or phenytoin instead.

Sinus rhythm is shown in Fig 58a.

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