LETTER
Conduction Disturbances Associated with Venlafaxine
Alain Combes, MD; Gilles Peytavin, MD;
and David Théron, MD
16 January 2001 | Volume 134 Issue 2 | Pages
166-167
TO THE EDITOR:
Venlafaxine is a new antidepressant drug that inhibits serotonin
and norepinephrine reuptake. In clinical trials, venlafaxine
was found to be safe and effective (1).
However, substantial changes in vital signs (hypertension and
hypotension) (2) and
cardiac rhythm abnormalities (3) have
been observed in a few patients, notably the elderly. We describe a
case of venlafaxine-associated conduction disturbances that were
reversed after administration of sodium bicarbonate.
A 44-year-old woman took an overdose of venlafaxine (3 g), clonazepam
(20 mg), lormetazepam (24 mg), and thioridazine (10 mg). She
was intubated and admitted to our medical intensive care unit.
Gastric lavage was performed and activated charcoal was administered.
The initial electrocardiograph tracing showed a sinus rhythm
and incomplete right bundle-branch block (Figure on page
167, top). Two hours later, isotonic saline and norepinephrine
were infused because of marked vasoparalysis. Ten hours after
admission, a second electrocardiogram (Figure,
middle) showed atrial fibrillation with wide QRS complexes.
Within 15 minute of infusion of 100 mL of 1 M of sodium bicarbonate,
a sinus rhythm with narrow QRS complexes was obtained (Figure,
bottom). No further rhythm or conduction abnormality was noted
over the following days.
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Figure.
Electrocardiography (ECG) tracings in a patient with venlafaxine
toxicity. Top. ECG tracing upon intensive care unit
admission showing a sinus rhythm with an incomplete right
bundle-branch block. Middle. Ten hours later, the ECG showed
atrial fibrillation and wide QRS complex tachycardia. Bottom.
The ECG tracing recorded 15 minutes after infusion of 100 mL of 1 M
of sodium bicarbonate shows the return to sinus rhythm with narrow
QRS complexes.
| |
A recent report demonstrated that venlafaxine blocks the fast
inward sodium current in a concentration-dependent manner in
isolated guinea pig ventricular myocytes, thereby promoting
membrane-stabilizing effects (4). Our
observations support this experimental result and confirm the in vivo
efficacy of sodium bicarbonate in reversing the membrane-stabilizing
activity of venlafaxine.
Physicians who prescribe antidepressant drugs should be aware of
the potential risk associated with venlafaxine, which shares many of
the known toxic effects of tricyclic agents. We strongly recommend
prolonged surveillance in an intensive care unit for this type of
poisoning and the use of alkalinizing agents to treat severe cardiac
conduction disturbances.
| Author
and Article Information
|
Hôpital Bichat; 75877 Paris
Cedex 18, France (Combes, Peytavin, Théron)
1. Rudolph RL, Derivan AT. The safety and tolerability of venlafaxine
hydrochloride: analysis of the clinical trials database. J Clin Psychopharmacol.
1996;16:54S-59S; discussion 59S-61S. [PMID: 0008784648].
2. Feighner JP. Cardiovascular safety in depressed patients:
focus on venlafaxine. J Clin Psychiatry. 1995;56:574-9[PMID: 0008530334].[Medline]
3. Peano C, Leikin JB, Hanashiro PK. Seizures,
ventricular tachycardia, and rhabdomyolysis as a result of ingestion of
venlafaxine and lamotrigine. Ann Emerg Med. 1997;30:704-8[PMID: 0009360588].[Medline]
4. Khalifa M, Daleau P, Turgeon AJ. Mechanism of
sodium channel block by venlafaxine in guinea pig ventricular myocytes. J
Pharmacol Exp Ther. 1999;291:280-4[PMID: 0010490914].[Abstract/Free Full Text]
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