[Catecholamine induced ventricular tachycardia: a cause of severe syncope during adolescence].

A 15-year-old female teenager had recurrent syncopes and had been unsuccessfully treated for 6 years for seizures and hysteria. Syncopes were always triggered by emotions, or efforts, but electrocardiograms were normal between the episodes. A 24-hour-monitoring during a syncope, and provocative tests (exercise testing and isoprenaline administration) showed severe ventricular arrhythmias with premature polymorphous beats, followed by ventricular tachycardia and then ventricular fibrillation. These "catecholamine-induced" ventricular tachycardias are very rare but are always fatal without treatment. Syncopes are stress-induced and the diagnosis is almost always delayed, because the patients have a normal electrocardiogram, with normal QT interval. The arrhythmia appears beyond a "threshold" sinus rate and is easily reproducible by exercise testing. Betablockers are the only efficient treatment to prevent sudden death.