Fatal Digoxin Toxicity

[!xe "Digoxin toxicity:VT:fatal DCC" \i!]

Report:

Fascicular tachycardia 178/min.

Comment:

There is no definite atrial activity. The QRS complex is just over 0.12" long and has an initial R wave in V1 of 0.04" suggestive of ventricular origin. The axis is indeterminate, ‘Northwest’ axis, also suggestive of ventricular origin. Her 12-lead ECG before the tachycardia (not shown) had QRS of normal duration and axis. The rhythm strip below (Fig 76a) is taken on modified MCL1, with rSr’ rather than RSR’ pattern; it still shows the time to S wave nadir to 0.06”.

The most likely diagnosis is a fascicular VT, consistent with digoxin toxicity. In fact the Cardiology Registrar knew that serum digoxin was in the toxic range (3.9 ng/L) but the Cardiologist (on the telephone, from his Rooms) requested DC cardioversion and confirmed his orders when I made the Registrar ring back to check. Presumably the tachycardia was thought to be SVT and not due to digoxin!

DC cardioversion went ahead, by the Registrar and the Consultant Anæsthetist, and produced, not surprisingly, intractable VF from which she could not be resuscitated.

The treatment of choice in this situation could have been administration of potassium, magnesium, phenytoin, or pacemaker cardioversion. Now, a decade later, specific digoxin antibody would be used. DC shock remains contraindicated; it would be so even if the diagnosis of the supposed SVT was correct. Digoxin is quite capable of producing an aberrant junctional tachycardia as well as VT.

ECG has always been a dangerous investigation71.

Fig 76a. Rhythm strip in CCU prior to fatal intervention. 77. 79 year old man with previous myocardial infarction? Where?

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