Torsades De Pointes - Tachycardia

Explanation: TdP tachycardia is the most frequently overlooked special form of polymorphic ventricular tachycardia in which a typical high-frequency, spindle-shaped QRS amplitude fluctuation occurs and is based on the often recurrent intractable ventricular tachycardia.

Predisposing factors are bradycardia and electrolyte disorders such as hypokalemia and hypomagnesemia, which are associated with prolonged repolarization.

It is the classic vital threatening arrhythmia in long-QT syndrome, which, in addition to the rare congenital forms, is now known as v.a in case of drug overdose and as side effect in case of antiarrhythmic drugs (classic in case of quinidine, sotalol, procainamide, flecainid, propafenone, and more rarely amiodarone) or by other drugs (erythromycin, amantadine, pentamidine, ketoconazole, cisapride, probucol, tricyclic antidepressants, etc.).

All different antiarrhythmic drugs are contraindicated in this rhythm disorder, which usually develops from the bradycardia, as they can lead to further bradycardia and prolong repolarization up to the complete heart block under these conditions..

The therapy of choice for TdP is the administration of 1-2 grams of magnesium sulphate (corresponding to 100 - 200mg magnesium) in recurrent TdP tachycardia or of course defibrillation in pulseless TdP with loss of consciousness (= resuscitation) with subsequent magnesium administration..

To prevent the recurrence of TdP, tachycardia of the basic rhythm, to shorten the repolarization period, with pacemaker stimulation is the method of choice. The pacemaker frequency is increased until TdP no longer occurs. This can make a stimulation frequency of up to 120/min necessary in individual cases. Alternatively, an isoproterenolperfusor with the aim of tachycardization can be attempted. However, this therapy regime harbours specific dangers such as circulatory shock caused by proarrhythmia, which is particularly prevalent when there is a replacement rhythm with broad chamber complexes. "Here extreme caution would be required in titrating the correct dose.