RT Book, Section A1 Freeman, Brian S. A2 Freeman, Brian S. A2 Berger, Jeffrey S. SR Print(0) ID 1102566582 T1 Defibrillators T2 Anesthesiology Core Review: Part One Basic Exam YR 2014 FD 2014 PB McGraw-Hill Education PP New York, NY SN 9780071821377 LK accessanesthesiology.mhmedical.com/content.aspx?aid=1102566582 RD 2024/03/28 AB During defibrillation, a randomly timed high-voltage electric current is discharged across two electrodes placed on the chest of a patient in cardiac arrest. The purpose of defibrillation is to simultaneously depolarize a large critical mass of myocardium. As a result, nearly all ventricular myocytes will enter their absolute refractory periods, when no action potentials can be generated. Successful defibrillation means that the reentry focus underlying the ventricular dysrhythmia is now either quiescent or eliminated. At this point, the pacemaker with the highest automaticity (such as the sinus or atrioventricular nodes) will take over control of ventricular pacing and contraction with a proper sequence of depolarization and repolarization.