Wireless microstimulators for treatment of peripheral vascular disease

Electrical stimulation of the rat sciatic nerve for the potential treatment of peripheral vascular disease was investigated using a chronically implanted millimeter-wide ultrasound-powered neurostimulator. The implanted device was sufficiently small as to pass through a 15 Ga syringe needle and produce as much as 25% increases in blood flow in a normal rat. The neurostimulator was powered by pulsed 500 kHz ultrasound applied to the rat skin over the implant at safe power levels on the order of 10-100 mW/cm². Vasodilation was produced using pulse amplitudes just below that needed to evoke rat hindlimb motor response and at widths of 1 ms and frequency of 3 Hz for 5 periods of 30s with 120s of resting time. The results using a laser Doppler flowmetry system showed the neurostimulator to be an effective and wireless method of increasing peripheral blood flow in the rat hindlimb.