A TECHNIQUE FOR CONDUCTING NONINVASIVE CARDIAC ELECTROPHYSIOLOGY STUDIES IN CONSCIOUS SWINE

A noninvasive method was developed in swine for conducting cardiac ele ctrophysiology (EP) studies without the potential confounding effects of sedatives or anesthetics. Following a 1-week conditioning regimen i n the EP laboratory, 3-month-old Hanford miniature swine underwent tra nsvenous pacemaker (PM) implantation under isoflurane anesthesia. Two bipolar screw-in pacing leads were inserted into the left external jug ular vein, with one positioned in the right atrial appendage and one i n the myocardium at the right ventricular apex. The leads were attache d to a multiprogrammable pulse generator, and the pacing system was pl aced in a subcutaneous pocket. At weekly intervals following implantat ion, conscious, unsedated swine were restrained in a sling for noninva sive programmed stimulation (NIPS) using a programmable telemetry syst em. A NIPS protocol to induce arrhythmias was performed separately for the atrium and ventricle. Data for this model are reported. Complicat ions occurred in 6 of 26 animals studied and included one infection of the PM pocket, three cases of dislodgement of the atrial lead, and ro tation of the generator within the pocket in two animals, preventing c ommunication with the PM. This technique has been used to perform EP s tudies successfully in swine and has been utilized in a variety of stu dies of the cardiac conduction system.