Sotalol Torsades de Pointes

Report:

Sinus rhythm 67/min

Borderline first degree AV block

PR 0.20”

VEBs, frequent

Runs (3-beat, 5-beat) of multiform ventricular tachycardia

Incomplete LBBB

Prolonged QT interval

Comment:

The patient’s torsades (Fig 56a) were treated by MgSO4, then xylocaine, then DC countershock in CCU. Sotalol has now replaced flecainide as leading cause of iatrogenous torsades in this hospital. Drug-induced (acquired) long QT syndrome has been reviewed recently54.

The important distinction between torsade de pointes and multiform VT rests on underlying bradycardia and prolonged QT interval being associated with the former. In sustained tachycardia, the observation of “spindles” and axis rotation does not distinguish between the two. A representative 12-lead ECG in sinus rhythm is shown below (Fig 56b).

56a. Torsades de pointes. The QT interval increases with the cycle length, creating a vicious circle.

56b. The anteroseptal T wave inversion may be due to preceding VT or syncope. 57. 68 year old lady who had atrial tachycardia 175-180/min with 2:1 block. She received three quinidine bisulphate tablets at midnight and another two, with 0.5 mg digoxin, two hours later. Fifteen minutes after that the tachycardia shown below developed, reverting spontaneously several times over the next four hours. There was no response to xylocaine.