Abstract: objective To analyze the cause of frequent shocks in implantable cardioverter defibrillators（ICD） and to ascertain a means of troubleshooting. Frequent shock is defined as five or more shocks per 12 months or three or more shocks per 24 hours. Method From Jan 2006 to Jul 2012, a total of 80 patients received an ICD device (60 patients for secondary prevention and 20 patient for primary prevention). Result During the follow-up period of 1 year to 6 years, 10 patients (12.5%) experienced frequent shocks. Of the 10 patients, five was implanted with single-chamber ICD, four patients with dual-chamber ICD and another patient with CRTD. Some of the causes of frequent shock include electrical storms induced by heart failure, misdiagnosis of superventricular tachycardia(SVT) as ventricular tachycardia(VT), failure of defibrillation due to high defibrillatioin threshold (DF) and frequent shock for non-sustained VT. The management include: correcting the underlying heart failure to reverse the electrical instability of the myocardium, removing the drug that may increase DF, reducing ICD shock using device programming and administration of amiodarone in association with beta-blockers. Conclusion Optimal programming of ICDs and the administration anti-arrhythmia drugs amiodarone and beta-blockers effectively reduce ICD shocks.

Key words: implantable cardioverter defibrillator , frequent shock