Correspondence

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American Journal of Emergency Medicine

journal homepage: locate/ ajem

Electrocardiographic changes in tricyclic antidepressant toxicity?,??,?

To the Editor,

We thank Jambet et al [1] for their interesting article on psychiatric drug-induced fatal complication. We would like to emphasize the importance of detecting one of these psychiatric medication toxicities by a bedside tool. We recently had a 64-year-old woman with depression who presented to the emergency department unrespon- sive after ingesting fifty 100-mg amitriptyline tablets 2 hours prior. The patient was intubated and admitted to the intensive care unit. Her initial electrocardiogram (ECG) is shown in Fig. In the setting of tricyclic antidepressant (TCA) toxicity, a QRS duration greater than 100 milliseconds carries a 26% chance of seizure and up to a 50% chance of ventricular arrhythmia with a QRS duration greater than 160 milliseconds [2]. The risk of seizures and arrhythmias is also significantly higher with RaVR amplitude of 3 mm or more or with a rightward shift in the terminal 40 milliseconds frontal plane QRS vectors (deep and slurred S wave in lead I and aVL and R wave in Lead aVR, respectively) [3].

The main pathophysiology of cardiac Conduction abnormalities is fast sodium channel inhibition in the His-Purkinje system as well as the atrial and ventricular myocardium, leading to a widened QRS complex and prolonged PR and QT intervals. Sinus tachycardia is common but the bradyarrhythmias due to atrioventricular block and the supraventricular and Ventricular tachyarrhythmias may occur. The incidence of ventricular tachycardia and fibrillation is approxi- mately 4% in TCA overdose [4].

Sodium bicarbonate therapy with a goal serum pH of 7.50 to 7.55 is the mainstay treatment of TCA toxicity in patients who develop a QRS interval greater than 100 milliseconds or ventricular arrhythmia [5]. The resolution of ECG changes might take hours to days requiring prolonged bicarbonate infusion. The evidence supporting the use of antiarrhythmic

medications in the setting of TCA toxicity is limited. The use of class IA and IC antiarrhythmics is contraindicated based on sodium channel blocking properties, which are similar to that induced by TCA.

Promporn Suksaranjit MD Supawat Ratanapo MD Narat Srivali MD Saeed Ahmed MB, BS

Wisit Cheungpasitporn MD Daych Chongnarungsin MD Edward F. Bischof MD Department of Internal Medicine

Bassett Medical Center Cooperstown, NY 13326, USA

E-mail address: [email protected] http://dx.doi.org/10.1016/j.ajem.2012.12.038

References

1. Jambet S, Guiu B, Olive-Abergel P, Grandvuillemin A, Yeguiayan JM, Ortega- Deballon P. Psychiatric drug-induced fatal Abdominal compartment syndrome. Am J Emerg Med 2012;30(3):513.e5-7.
2. Boehnert MT, Lovejoy Jr FH. Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of triCyclic antidepressants. N Engl J Med 1985;313(8):474.
3. Thanacoody HK, Thomas SH. Tricyclic antidepressant poisoning: cardiovascular toxicity. Toxicol Rev 2005;24(3):205-14.
4. Goldberg RJ, Capone RJ, Hunt JD. cardiac complications following tricyclic antidepressant overdose. Issues for monitoring policy. JAMA 1985;254(13): 1772.
5. Hoffman JR, Votey SR, Bayer M, Silver L. Effect of hypertonic sodium bicarbonate in the treatment of moderate-to-severe cyclic antidepressant overdose. Am J Emerg Med 1993;11(4):336-41.

   ? Funding: None.

   ?? Conflict of interest statement for all authors: We do not have any financial or

   nonfinancial potential conflicts of interest.

   ? Authors’ contributions: All authors had access to the data and a role in writing

   the manuscript.

   0735-6757/$ - see front matter.

   

   Fig. The ECG showed sinus rhythm with first-degree atrioventricular block at a rate of 69 beats per minute. The QRS complex is wide (126 milliseconds) with slurred S wave in lead I and R wave in lead aVR. The QT interval is prolonged with QTc interval of 552 milliseconds.