CARDIAC-RHYTHM FOLLOWING CONVERSION OF VENTRICULAR TACHYARRHYTHMIAS BY INTERNAL SHOCK DELIVERY

The purpose of this retrospective study is the analysis of dysrhythmia s following internal cardioversion/defibrillation of ventricular tachy cardia (VT) or fibrillation (VF) and to discuss their relevance to the therapy with automatic implantable devices. Therefore, 304 internal c onversions of VT/VF during and/or after implantation of automatic defi brillators were evaluated in 51 patients. Significant post-shock arrhy thmias (bradycardia, atrial fibrillation, non-sustained VT of greater than or equal to 10 cycles) were absent after 89 % of internal shocks. Pauses of > 2 s were observed in 2/9 patients without VVI-back-up pac ing. The heart rate was greater than or equal to 50 bpm in 10/51 patie nts.,Atrial fibrillation occurred in 7 patients. Non-sustained, mostly polymorphic VT consisting of greater than or equal to 10 cycles follo wed 18/304 (6 %) internal shocks in 13 patients. The VT rate was great er than or equal to 200/min in 17/18 episodes and triggered an inadequ ate shock once. The incidence of non-sustained VT post-shock was unrel ated to shock energy, type, and duration of the converted arrhythmia. In conclusion, automatic implantable devices should provide back-up pa cing. Tachycardic rhythms can mislead automatic interpretation of the effect of internal shocks.