Login to Access Video or Poster Abstract: MP25-20
Sources of Funding: Partial funding through a grant from Boston Scientific.

Introduction

We previously developed a novel shape memory alloy prosthesis using a lasercut Nitinol extruded tube that expands and becomes rigid when activated to simulate an erection. We also described how it is possible to activate it using magnetic induction (MI). To better understand the thermal safety and efficacy of this approach in tissue, we tested MI activation using an in vitro animal tissue model.

Methods

We used a commercially available magnetic inductor with a power of 1000W and a custom made 2mm copper coil of 3 turns of 4cm diameter. The prosthesis or nitinol tube was inserted down the length of a pork-product sausage. Two thermocouples were placed to measure temperature changes: (1) on the exoskeleton, and (2) 2 mm away in the tissue. The sausage with the embedded prosthesis was positioned in the middle of the coil and the miniductor activated. Temperature tracings were recorded overtime. As a control, the same setup was placed on a laboratory hot plate with temperature set at 43C.

Results

With the hot plate, the tissue and prosthesis gradually rose in temperature together from 23C to 43C over 300 secs with conduction of heat. Using magnetic induction to the Nitinol tube, the prosthesis temperature rose from 23C to 43C in 20 secs, with only a 2C change in tissue temperature. With the lasercut prosthesis 43C was reached in 400 secs with a 4-5C rise in surrounding tissue. With magnetic induction tissue temperature never rose above 5C from baseline. In all cases, the activated device simulated previously described erection parameters.

Conclusions

Magnetic induction effectively penetrates animal tissue and allows for potentially faster heat transfer and activation of a novel shape-memory penile prosthesis. There is no evidence of any thermal damage to local tissues from this process of activation. Further design optimization can enhance the magnetic induction process.

Funding

Partial funding through a grant from Boston Scientific.