title: The effects of endocardial defibrillation on left ventricular function: a transoesophageal echocardiographic study.
abstract: This study evaluates the immediate effects of the endocardial electrical shocks delivered by a transvenous defibrillation system on left ventricular (LV) function in a pig model. A triple-lead system consisting of two endocardial electrodes, in the right ventricular apex and the junction of superior cava-right atrium, and a custom-made defibrillation can implanted subcutaneously in the thorax was set up in 10 close-chest pigs. Transesophageal echocardiography with two dimensional image, m-Mode, and pulse Doppler was performed at baseline and after several episodes of fibrillation/defibrillation (F/DF). Each animal underwent an average of 8 (range 6 to 11) episodes of ventricle F/DF for a total of 210 (range 165 to 290) joules of biphasic-waveform defibrillation shocks. Heart rate, blood pressure, LV end-systolic area, end-diastolic area and fractional area contraction, isovolumic relaxation time, and both ratios of velocities and time-velocity integrals in transmitral Doppler flow E and A waves were unchanged after the shocks. This animal study suggests that multiple countershocks up to 210 joules delivered by a transvenous defibrillation system do not cause LV global systolic and/or diastolic dysfunction.
authors.affiliation: Division of Cardiovascular Medicine, University of Kentucky Medical Center, Lexington, USA.
authors.forename: K
authors.initials: K
authors.lastname: Wang
authors.forename: F
authors.initials: F
authors.lastname: Garcia
authors.forename: F M
authors.initials: FM
authors.lastname: Leonelli
mesh_terms: D000818:Animals; D003627:Data Interpretation, Statistical; D017147:Defibrillators, Implantable; D018619:Echocardiography, Doppler, Pulsed; D017548:Echocardiography, Transesophageal; D004554:Electric Countershock; D004567:Electrodes, Implanted; D005260:Female; D006439:Hemodynamics; D008297:Male; D013552:Swine; D016277:Ventricular Function, Left