RESUMO
The term "electrical storm" (ES) indicates a state of cardiac electrical instability manifested by several episodes of ventricular tachyarrhythmias (VTs) within a short time. In patients with an implantable cardioverter-defibrillator (ICD), ES is best defined as three appropriate VT detections in 24h, treated by antitachycardia pacing, shock or eventually untreated but sustained in a VT monitoring zone. ES seems to have a low immediate mortality (1%) but frequently (50-80%) leads to hospitalization. Antiarrhythmic drugs have been shown to be very effective in treating ES in patients without ICD, whereas in ICD recipients, device programming is probably a key issue to prevent ES. Since sympathetic overreactivity is an important trigger, the risk of shock delivery should be minimized. Antitachycardia pacing can successfully terminate a significant percentage of fast VTs. Important parameters such as the number of VT cycles needed for VT detection can be increased from nominal values to allow spontaneous termination, and safety features that deliver a shock after a programmable time window independent of programming of antitachycardia pacing (sustained rate duration) should be prolonged or disabled. In some cases it may be advisable to turn off the ICD tachy mode to avoid multiple ineffective shocks. Substrate mapping and VT ablation may be useful for the treatment and prevention of ES.
