Multifunctional implantable nerve stimulator for cardiac assistance by skeletal muscle.

Different methods are used, clinically and experimentally, to assist severely impaired heart function by means of skeletal muscle. The efficiency of these methods is restricted by skeletal muscle losing strength after transpositioning and during conditioning and not being sufficiently resistant to fatigue. This is mainly due to the nonphysiological activation of the nerves by electrical stimulation. We have developed a battery operated, ECG triggered multichannel implant that is capable of implementing various advanced stimulation techniques. The stimulator can activate 2 skeletal muscles via the motor nerves. It allows for application of multichannel stimulation methods, i.e., carousel stimulation and sequential stimulation, as well as the programming of optimized pulse trains. Synchronization delay and burst duration can be automatically and dynamically adapted to the heart rate. The multichannel stimulator is hermetically sealed in a titanium case. Its calculated life span on the basis of the integrated battery is 3-5 years, depending on the programmed stimulation parameters. The implant dimensions are 65 x 17 mm (diameter x height), and it weighs 93 g. The implant has been tested in vitro as well as in vivo.