Electrocardiogram of an 85 year-old woman hospitalized two weeks earlier with new onset atrial fibrillation and congestive heart failure. Discharged home on Digoxin 0.125 mg daily, Metoprolol 25 mg twice daily, Amiodarone 200 mg daily, Lasix 20 mg twice daily, Altace 5 mg daily and Coumadin dose adjusted to INR. The patient presented to hospital again with weakness, dizziness, lightheadedness and blurred vision.

Rate 51/min
PR complete AV block
QRS 0.09 sec
QT 0.34 sec
QTc 0.32 sec
QRS axis +35º

Interpretation: Abnormal ECG. Complete AV block with escape nodal rhythm. Shortened QT interval and scooped or sagging ST segment depression in multiple leads suggestive of digitalis effect.

The patient was clinically dehydrated, creatinine increased from 138 on previous admission to 299 µmol/l, urea from 9.4 to 28.7 mmol/l. Digoxin level was toxic at 5.7 nmol/l (normal range 1.3 – 2.6). Potassium 3.8 mmol/l. INR theurapeutic at 2.7. The patient was rehydrated, Digoxin, Metoprolol, and Amiodarone were stopped. Within few hours complete heart block resolved. After 8 days creatinine 88 µmol/l. The patient remained in sinus rhythm with first degree AV block.

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