Induction heater system for shape memory medical implants and method of activating shape memory medical implants within the mammalian body
A method of altering a medical implant having a shape memory portion includes the use of a probe having a tip provided with an induction coil. The induction coil is electrically coupled to an induction power supply. The induction coil is inserted into the mammalian body. The power supply is activated at a suitable frequency to cause the induction coil to generate a magnetic field, wherein such magnetic field induces eddy currents in the shape memory portion of the implant which are sufficient to heat the shape memory portion of the implant to a phase transformation temperature to effect shape change of the implant.
1. A system, comprising:
a) an ossicular prosthesis implantable in the middle ear, said prosthesis comprising a shape memory portion, wherein upon heat activation to a phase transformation temperature, said shape memory portion changes from a first configuration to a second configuration; and
b) an induction heater system for heat activation of said shape memory portion, said induction heater system comprising,
i) a user-manipulable handle,
ii) a elongate probe extending from said handle, said probe having a distal tip extending along a longitudinal axis and having a diameter of between 0.3 mm and 2.0 mm to allow insertion into a small surgical opening,
iii) an induction coil coupled to said distal tip and displaced from said handle by said probe, said induction coil made of an electrically conductive material, said induction coil having a dimension in a direction transverse to the longitudinal axis that does not exceed 4 mm, and
iv) a first connector for coupling said induction coil to an alternating current radio frequency induction power supply,
wherein said handle is adapted for a surgeon to manually engage the handle to support and manipulate the probe and induction coil during an operation.
2. A system according to claim 1 , wherein:
said shape memory portion comprises nickel-titanium.
3. A system according to claim 1 , wherein:
said coil comprises copper.
4. A system according to claim 1 , wherein:
said coil consists essentially of three to fifteen windings.
5. A system according to claim 1 , wherein:
said coil includes an insulative sheath.
6. A system according to claim 1 , further comprising:
an induction power supply capable of operating at a frequency between 300 KHz and 1MHz, said power supply includes a second connector for connection to said first connector.
7. A system according to claim 1 , wherein:
said probe is rigid and includes a proximal end and a distal end, and said proximal and distal ends extend at an angle relative to each other.
8. A system comprising:
a) an induction heater system including,
i) a speculum having a larger proximal end and a smaller distal end and an opening extending therethrough,
ii) an induction coil coupled to said smaller distal end, said induction coil made of an electrically conductive material, and
iii) a connector for coupling said induction coil to an alternating current radio frequency induction power supply; and
b) an ossicular prosthesis implantable in the middle ear, said prosthesis comprising a shape memory portion, wherein upon heat activation to a phase transformation temperature by said induction coil, said shape memory portion changes from a first configuration to a second configuration.
9. A system according to claim 8 , wherein:
said coil comprises copper.
10. A system according to claim 8 , wherein:
said coil consists essentially of three to fifteen windings.
11. A system according to claim 8 , wherein:
said coil includes an insulative sheath.
12. A system according to claim 8 , further comprising:
an induction power supply capable of operating at a frequency between 300 KHz and 1MHz, said power supply includes a second connector for connection to said first connector.
13. A system according to claim 6 , wherein:
said power supply generates a pulsed energy activation profile that operates to limit heat in said coil which can be transferred to tissue in the middle ear.
14. A system according to claim 1 , wherein:
said probe has a proximal portion with a first diameter, and said distal tip has a second diameter smaller than said first diameter, said second diameter less than 2 mm.
15. A system according to claim 14 , wherein:
said second diameter is between 0.3 mm and 1.5 mm.
16. A system according to claim 15 , wherein:
said probe includes a bend between said proximal portion and said distal tip that angles said proximal portion and said distal tip relative to each other.
17. A system according to claim 16 , wherein:
said probe has a length between 20 mm and 70 mm.