Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.
The short QT syndrome, a recently discovered ion channel disorder, combines shortened repolarization, a predisposition to atrial and ventricular fibrillatory arrhythmias, and a risk of sudden death. Few cases have been reported, but the prevalence may be underestimated. This syndrome might account for some cases of unexplained ventricular fibrillation in patients with otherwise healthy hearts. Patients have abnormally short QT intervals and refractory periods, and atrial/ventricular fibrillation can be triggered during investigations. Gain-of-function mutations have been detected in three genes encoding potassium channels. Treatment is based on defibrillator implantation, sometimes as a preventive measure. Quinidine may be beneficial in certain cases.
A case of an electrical storm occurring in a patient implanted with a cardioverter-defibrillator for Brugada syndrome is reported. Recurrent ventricular fibrillation was initiated by short-coupled isolated monomorphic ventricular premature beats probably originating from the right ventricular outflow tract, associated with a manifest electrocardiographic pattern of Brugada syndrome. Infusion of atropine accelerated the heart rate but did not prevent ventricular fibrillation, however, low doses of isoprenaline quickly obviated any recurrence of ventricular fibrillation. This was associated with the disappearance of the short-coupled premature beats together with a normalization of the electrocardiographic pattern. Possible mechanisms are discussed according to the accepted pathophysiological hypothesis.
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