RESUMO
This study evaluates the immediate effects of the endocardial electrical defibrillation delivered by two transvenous defibrillation systems on left ventricular (LV) function in the animal model. Automatic cardiac defibrillation systems with bipolar leads (group I) and tripolar leads (group II) were placed in the hearts of 10 dogs (group I) and 10 pigs (group II),respectively. Transesophageal echocardiography with two dimensional image, M-mode and pulse Doppler were performed at baseline and after several episodes of defibrillation (DF). Each animal in group 1 underwent 4 DF with 64 Joules; the animals in group2 underwent an average of 8 DF with a total of 210 Joules. LV fractional area contraction, isovolumic relaxation time, and both ratios of velocities and time-velocity integrals in transmitral Doppler flow E and A waves exhibited no significant change after the shocks. This study suggests that the repeated low-energy electrical countershocks delivered by two transvenous defibrillation systems do ndt cause LV global systolic and/or diastolic dysfunction.