Management of electrical instability after ICD implantation

Postoperative ventricular arrhythmias were studied in 52 patients receiving implantable cardioverter defibrillators (ICDs). A group of 9 patients was identified who experienced electrical instability (EI). The lead approach was thoracotomy in 6 and nonthoracotomy in 3 patients. In 8 of 9 patients VTs started soon after surgery. There was no evidence of ischemia, cardiac failure, electrolyte imbalance, or drug intoxication. The severity of ventricular arrhythmias varied from a considerable increase in incidence of well-tolerated VTs in 3 patients (1 incessant) to poorly tolerated frequent VTs in 6 patients (2 incessant). In 4 patients VTs led to cardiac failure. Ventricular arrhythmias during EI were refractory to antiarrhythmic drugs (AAD) in 7 of 9 patients. In 3 patients VTs accelerated into fast VT or VF with antitachycardia pacing (ATP) or cardioversion. The successful management of EI was: sedation in 4 patients (3 with midazolam 1 with temazepam), ATP and AAD in 2 patients, AAD and hemodynamic support in 2 patients, spontaneous resolution in 1 patient. All patients survived the period of postoperative EI. Two patients had a relapse of EI at 2- and 9-months postimplantation, respectively, one of whom eventually died.

EI occurred in 17% of patients after ICD implantation, had a varying degree of severity and required an individualized approach. Control of EI with AAD was successful in only 2 of 9 patients. Sedation with midazolam was useful in the management of EI.