Always have a high suspicion of digoxin toxicity in a patient taking digoxin presenting with the disoriented state.
Digoxin toxicity can cause a wide variety of arrhythmias. It is classically associated with supraventricular tachycardias but a slow ventricular response (e.g.: atrial tachycardia with high-grade AV block).
The other common rhythms include:
- Regularized atrial fibrillation (AF with complete heart block + accelerated junctional escape rhythm which produces a paradoxically regular rhythm)
- Bidirectional VT (polymorphic VT with QRS complexes alternating between LBBB and RBBB morphology)
Digoxin toxicity should be separated from the normal digoxin effect that can occur in patients taking the expected dose of digoxin. The digoxin effect (image below) includes sagging ST-segment depression, abnormal T waves (flat, inverted or biphasic) and a short QT.