Sudden cardiac death is the most frequent cause of death in industrialized countries. The most efficient interventiont in ventricular fibrillation is defibrillation in an appropriate timely manner. But since the intervention of defibrillation the optimal shock energy is unknown. As a too low energy is not able to terminate ventricular fibrillation a too high energy may cause asystole wich jeopardizes survival itself. We study the efficacy of different shock energies on the termination of ventricular fibrillatiion and survival.

Inclusion Criteria:

• out of hospital sudden cardiac death
• ventricular fibrillation

Exclusion Criteria:

• non cardiac death
• asystole