Unusual Tachycardia After Cocaine Use

Abstract

To the Editor We read with great interest a recent case report by Kawji. 1 It reports of a patient with bidirectional ventricular tachycardia (BVT) induced by cocaine use and mentions electrical cardioversion as a last resort, which we find is inappropriate.Treatment of BVT must first determine its cause. The causes of BVT are divided into toxic and nontoxic. Digoxin intoxication is the most common cause of BVT, but digoxin intoxication is not amenable to cardioversion because it produces calcium overload, which induces delayed after depolarization (DAD). Other causes, including aconite, cocaine, and caffeine intoxication, are all caused by DAD, although the ion imbalance between Na + , K + , and Ca 2+ is different.When BVT is suspected to be an acute phase transition caused by drugs, supportive treatments, such as gastric lavage, gastrointestinal decompression, and continuous kidney replacement therapy, are required to allow the body to excrete toxic alkaloids. In addition, for hemodynamically stable patients, Na + channel blockers can be used according to the mechanism of aconitine-induced arrhythmia; mexiletine, flecainide, and amiodarone may also be effective.Electrical cardioversion may be an alternative treatment for BVT when other antiarrhythmic drugs are ineffective; however, previous experience has shown that cardioversion is rarely effective. 2 When the patient is hemodynamically unstable, direct current cardioversion should be preferred because it is a safer cardioversion method than antiarrhythmic drugs. Timely application of electrical cardioversion has been shown to terminate a variety of cardiac arrhythmias and is believed to work by synergistically activating inactive voltagedependent sodium channels, thereby terminating automaticity. A growing number of case reports and clinical reviews of intoxicated BVT demonstrate limited effectiveness of electrical cardioversion for BVT. 3 This disappointing performance may