Abstract
Ventricular fibrillation (VF) is a lethal medical emergency that requires immediate defibrillation. VF is resistant when it persists after three or more defibrillator shocks. Successful defibrillation requires depolarisation of a critical mass of myocardium. Several variables, such as the length of time in VF, body type, total energy used, and energy waveform have been reported to be associated with the success rate of defibrillation. Correct paddle position and good contact force to create an adequate current flow through the heart is essential for defibrillation. We report a patient who developed VF because of acute myocardial infarction that was resistant to a total of 13 shocks. The cause of shock-resistant VF was diagnosed by noticing the skin marks caused by the defibrillator paddle that indicated incorrect paddle position and inadequate paddle force. By checking the skin marks, an emergency physician could make a correct diagnosis within a few seconds and save a patient.