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Some patients receive multiple appropriate shocks during a short period of time, arrhythmic electrical storm (malignant ventricular arrhythmias resulting in device intervention > or = 3 times during 24 hours). It is a common implantable cardioverter-defibrillator therapy-related complication. The objectives of this study were to determine the incidence, characteristics, prognostic implications and therapeutic options of electrical storm. This six years prospective study comprised 115 device recipients, who were followed for 510-2,100 days. Electrical storm occurred in 18.3% at 336 days (median) after the implantation, due to diverse causes. The patients with electrical storm had 12 arrhythmic episodes and 9 shocks (median) per electrical storm; 46.6% had more than one storm corresponding to the first recurrence in 60%. There were no deaths. Two additional control groups (with recurrences or not but without storm) were studied. Electrical storm was responsible for more frequent readmissions to the hospital as compared to the controls. The arrhythmic cluster could be terminated by a combined and individualized therapy (amiodarona and beta blockers specially); antitachycardia pacing was better tolerated than shocks. Arrhythmic storm represents a frequent, serious and unpredictable event in patients with implantable cardioverter-defibrillator. It occurrs early or late after the implantation and can be managed by combined therapy. It does not independently increase mortality.

Sudden cardiac death due to electrical causes in individuals with no evidence of structural heart disease is an important clinical and public health problem, and it is not yet solved. The objectives of this study were: to characterize patients reanimated from a sudden death event of electrical cause; to know the mediated evolution during a period of three years and to study premonitory electrical signs. 42 individuals were studied, 30 were male and 12 female, mean age 37.7 years, healthy heart, by clinic and paraclinic methods. Nine subpopulations were studied, being Brugada syndrome, long QT syndrome and idiopathic ventricular fibrillation the most frequent. Ventricular fibrillation and twisting of the points were the arrhythmias responsible for most death events. There were premonitory signs in 92.8% and clinical recurrences of life-threatening events in 71.4% but they were induced during programmed electrical stimulation only in 4 of 18 patients. Atrial fibrillation was the most frequent coexistent arrhythmia (19%). In summary, there are frequent premonitory signs (particularly atrial fibrillation), and also malignant arrhythmic recurrences but a poor inducibility at the electrophysiology laboratory. It is very difficult to stratify the risk because of the low predictive value of diagnostic methods.

Arrhythmias were studied at the early stage after rapid ligation of the left ventricular artery on an experimental model of arrhythmia in rabbits. The rabbits were subjected to thoractomy and ligation of the left ventricular artery under direct visualization. The electrocardiographic and hemodynamic parameters were recorded. Electrocardiographic signs of infarction and changes in rhythm were recorded in 60% of the animals. The rate of cardiac contractions and the arterial pressure decreased after the ligation. In the group in which practolol was applied the rate of arrhythmias dropped to 25%. The effect of adrenergic beta-block on acute occlusion of the coronary artery is discussed.