The term torsade de pointes refers to a ventricular tachycardia characterized by QRS complexes of changing amplitude that appears to twist around the isoelectric line and occurs at rates of 200-250/minute. Most cases of torsade de pointes are iatrogenically induced by drugs or electrolyte abnormalities. The most important feature is QT interval prolongation. Torsade de pointes was first described in 1966 in France by Dessertenne. The authors report a case of a fifty-year-old woman with medical history of corrective surgery for tetralogy of Fallot who was admitted to the hospital with pneumonia and atrial fibrillation and later developed recurrent episodes of polymorphic ventricular tachycardia with QT interval prolongation after i.v. administration of erythromycin. The episodes did not recur after discontinuation of erythromycin, and the QT interval returned to normal. The association of erythromycin with torsade de pointes has been reported in 18 cases to date. Erythromycin has been shown to produce electrophysiologic effects similar to those of class Ia and class III antiarrhythmic drugs on the cardiac muscle. This potentially fatal complication of a commonly used antibiotic is rare, but increased physician awareness is important, especially in patients with predisposing factors like electrolytes abnormalities, use of class Ia and Class III antiarrhythmic drugs, and presence of prolonged QT interval (congenital prolonged QT syndromes). This is the second case reported in a patient with previous cardiac surgery and erythromycin administration.

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