Electrical therapy for cardiovascular emergencies.

This presentation summarizes advances in electrical therapy of cardiovascular emergencies. The urgency of delivering definitive therapy is emphasized, and the roles of automatic internal and external defibrillators, practical external pacing, and mechanical techniques for cardioversion and defibrillation are evaluated. Standard position of the electroplates is recommended except in patients who have permanently implanted pacemakers. In these patients, the defibrillation electrodes should be at least 5 inches from the pacemaker generator. The energy requirement for defibrillation of ventricular fibrillation is reviewed, with the conclusion that the initial defibrillatory shock should be 200 J. The determinants of the transthoracic impedance are important, especially if low-energy shocks are to be used, since a high transthoracic impedance results in a poor success rate for defibrillation with low-energy shocks. When high-energy (360 J) shocks are to be used, transthoracic impedance appears to be of less importance.