[Usefulness of electrophysiologic studies. Report of 224 cases].

Two hundred and twenty four electrophysiologic studies were performed in 194 patients during a two-year period. One hundred and six (54.6%) had tachyarrhythmias: 21 had atrial tachycardia, 28 had the Wolff-Parkinson-White syndrome. Of 51 patients with a normal electrocardiogram a concealed left Kent bundle was observed in 21 cases and only one concealed right Kent bundle; functional James fibers were seen in 7 patients and Mahaim fibers in two. In 15 patients A-V nodal reentry was diagnosed and functional ectopy was observed in 5 patients. The sick-sinus-syndrome was seen in 24 patients and atrial arrest in three. Thirty patients underwent a second electrophysiologic study to evaluate proper antiarrhythmic therapy. Atrioventricular conduction was evaluated in 52 patients. A "suprahisian" delay was found in 34%, troncular lesions were diagnosed in 31%, a distal delay in 25% and mixed conduction disturbances in 10%. We conclude that electrophysiologic studies are a useful procedure to: 1) establish the etiologic diagnosis of tachyarrhythmias; 2) evaluate their potential danger; 3) objectively evaluate antiarrythmic therapy; 4) establish the need for surgical treatment; 5) give the topographic diagnosis and severity of A-V conduction disturbances and 6) indicate the need for definitive pacemaker implant.