Multifunctional implantable nerve stimulator for cardiac assistance by skeletal muscle

Different methods are used, clinically and experimentally, to assist severe ly impaired heart function by means of skeletal muscle. The efficiency of t hese methods is restricted by skeletal muscle losing strength after transpo sitioning and during conditioning and not being sufficiently resistant to f atigue. This is mainly due to the nonphysiological activation of the nerves by electrical stimulation. We have developed a battery operated, ECG trigg ered 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 met hods, i.e., carousel stimulation and sequential stimulation, as well as the programming of optimized pulse trains. Synchronization delay and burst dur ation can be automatically and dynamically adapted to the heart rate. The m ultichannel stimulator is hermetically sealed in a titanium case. Its calcu lated life span on the basis of the integrated battery is 3-5 years, depend ing 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 test ed in vitro as well as in vivo.