Single-lead electrocardiogram (ECG) showing bidirectional ventricular tachycardia (VT)

Rhythm strip showing bidirectional ventricular tachycardia (VT) which may be a manifestation of digoxin toxicity. This rare, life-threatening tachyarrhythmia is characterized by beat-to-beat changes in the polarity of consecutive premature ventricular complexes.

Normal rhythm strip in lead II. The PR interval is 0.15 sec and the QRS duration is 0.08 sec. Both the P and T waves are upright.