Examination of epimysial leads used to stimulate the latissimus dorsi muscle for cardiomyoplasty

Cardiomyoplasty is a new surgical treatment for heart failure in which the patient´s own latissimus dorsi muscle (LDM) is isolated, wrapped around the heart, and electrically stimulated to provide cardiac assistance. The present study examined the use of epimysial electrodes whereas clinically intramuscular electrodes are used. We hypothesized that epimysial electrodes, by their proximity to the nerve, should have better recruitment curves. In addition, since the electrodes do not encompass the nerve, damage to the nerve is not expected. To address these issues, the present study sequentially measured the epimysial lead characteristics during LDM training. Lead resistance started at its highest value after implantation and then decreased during the following week. Thereafter, a slight increase was observed during the last 4 weeks but not reaching the initial value. The recruitment properties were similar to what is seen in nervecuff electrodes: a very rapid recruitment curve with saturation at low voltages was found throughout the 4 weeks. These results indicate that epimysial leads are worthy of further investigation