Atypical ventricular tachycardia

Goldsmith, S., From, A.H. (1980). Arsenic-induced atypical ventricular tachycardia. N. Engl. J. Med. 303 1096-8. 

Krikler DM, Curry PV. Torsade de pointes, an atypical ventricular tachycardia. Br Heart J 1976 38(2) 117-20. 

Acute overdosage can result in both cardiovascular and neurologic effects. Ventricular dysrhythmias and hypotension are the most serious toxicities. Cardiac effects occur as a result of myocardial depression and depression of atrial, atrioventricular, and ventricular conduction. EKG changes will be evident. These EKG changes include a widening of the QT, PR, and QRS complexes ST depression and T inversion. Myocardial depression and vasodilation can cause hypotension to develop. Syncope can result from transient Torsade de Pointes (i.e., bursts of atypical ventricular tachycardia). Ventricular tachycardia and ventricular fibrillation may develop. Possible central nervous system (CNS) effects include lethargy, seizures, and coma. Other acute effects can include apnea. Signs of toxicity are expected to occur in... 

Agents that cause QT interval prolongation (QTc > 0.42 seconds) may produce atypical ventricular tachycardia (torsade de pointes). Torsade de pointes is characterized by polymorphous ventricular tachycardia that appears to rotate its axis continuously (Figure I-7). Torsade de pointes may also be caused by hypokalemia, hypocalcemia, or hypomagnesemia. 

C. QT interval prolongation and torsade-type atypical ventricular tachycardia (see p 14) have been associated with elevated serum levels of terfenadine or astemizole. Both of these drugs have been removed from the US market. 

Treat coma (p 19), seizures (p 22), hyperthermia (p 21), and atypical ventricular tachycardia (p 14) if they occur. 

Keren A, Tzivoni D, Golhman JM et al (1981) Ventricular pacing in atypical ventricular tachycardia. J Electrocardiol 14 201-205... 

For atypical or polymorphic ventricular tachycardia (torsade de pointes), do the following ... 

Sinus tachycardia accompanied by QRS interval prolongation may resemble ventricular tachycardia (see Figure 1-4, p 12). True ventricular tachycardia and fibrillation may also occur. Atypical or polymorphous ventricular tachycardia (torsade de pointes see Figure 1-7, p 15) associated with QT interval prolongation may occur with therapeutic dosing, but is actually uncommon in overdose. Development of bradyanhythmias usually indicates a severely poisoned heart and carries a poor prognosis. 

Lethal intoxication with yew leaves (T. baccata) presented with dizziness 1 hour after ingestion, nausea, diffuse abdominal pain, unconsciousness, weak breathing, tachycardia, brief ventricular flutter followed by bradycardia, and finally death by respiratory arrest and cardiac standstill the electrocardiogram showed atypical bundle branch block and absent P waves (10). 

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