Selectively flexible catheter and method of use
View Patent ↗Catheter assembly including an elongate shaft comprising a thermoplastic polymer such as a thermoplastic shape memory polymer having a pre-selected glass transition temperature (Tg) and a means for heating the thermoplastic polymer, wherein the thermoplastic polymer is in a rubbery state at temperatures above the glass transition temperature and is in a glassy state at temperatures below the glass transition temperature. The elongate shaft may be selectively heated and cooled to provide sufficient flexibility and retention during a medical procedure.
1. A catheter having selectively varying flexibility including an elongate shaft having a proximal end, a distal end, a length and a lumen extending therethrough, the elongate shaft comprising:
a polymer layer including a thermoplastic shape memory polymer extending along at least a portion of the length of the elongate shaft, the thermoplastic shape memory polymer having a pre-selected glass transition temperature (Tg), wherein the polymer layer includes an inner layer and an outer layer,
an electrically conductive heat conductive member extending between the inner layer and the outer layer within at least a portion of the thermoplastic shape memory polymer, and
an outer tubular member disposed about at least a portion of the thermoplastic shape memory polymer, and
an electrical source electrically connected to the heat conductive member and configured to, when active, heat the thermoplastic shape memory polymer to a temperature about the glass transition temperature through electrical resistance of the heat conductive member.
2. The catheter of claim 1 , wherein the pre-selected glass transition temperature (Tg) is greater than about 37° C.
3. The catheter of claim 1 , wherein the pre-selected glass transition temperature (Tg) is between about 38° C. and about 80° C.
4. The catheter of claim 1 , wherein the pre-selected glass transition temperature (Tg) is between about 50° C. and about 80° C.
5. The catheter of claim 1 , wherein the pre-selected glass transition temperature (Tg) is between about 60° C. and about 70° C.
6. The catheter of claim 1 , wherein the heat conductive member is a heat conductive coil.
7. The catheter of claim 1 , wherein the heat conductive member is subjected to a thermal energy source, wherein the thermal energy source transfers thermal energy through the heat conductive member.
8. The catheter of claim 7 , wherein the thermal energy heats the thermoplastic shape memory polymer above the pre-selected glass transition temperature (Tg).
9. The catheter of claim 7 , wherein the thermal energy heats the thermoplastic shape memory polymer above a body temperature.
10. The catheter of claim 9 , wherein the body temperature is about 37° C.
11. The catheter of claim 1 , wherein the outer tubular member is a micromachined metallic tube including a plurality of apertures.
12. The catheter of claim 1 , further comprising an inner liner disposed in the lumen of the elongate shaft.
13. The catheter of claim 1 , further comprising a polymer tip disposed at the distal end of the elongate shaft.
14. The catheter of claim 6 , wherein the heat conductive coil extends substantially the entire length of the elongate shaft.
15. The catheter of claim 1 , wherein the thermoplastic shape memory polymer extends substantially the entire length of the elongate shaft.
16. A catheter assembly including a catheter having selectively varying flexibility comprising:
an elongate shaft having a proximal end, a distal end, a length and a lumen extending therethrough, the elongate shaft including;
a polymer layer including a thermoplastic polymer extending along at least a portion of the length of the elongate shaft, the thermoplastic polymer having a pre-selected glass transition temperature (Tg), the polymer layer having an inner surface and an outer surface, and
an outer tubular member disposed about at least a portion of the polymer layer;
an electrically conductive heat conductive member extending between the inner surface and the outer surface of at least a portion of the polymer layer; and
an electrical source electrically connected to the heat conductive member and configured to, when active, heat the polymer layer thermoplastic polymer to a temperature about the glass transition temperature through electrical resistance of the heat conductive member.
17. The catheter assembly of claim 16 , wherein the heat conductive member is disposed between the polymer layer and the outer tubular member.
18. The catheter assembly of claim 17 , wherein the heat conductive member is a heat conductive guidewire.
19. The catheter assembly of claim 17 , wherein the heat conductive member is a heat conductive coil.
20. The catheter assembly of claim 19 , wherein at least a portion of the thermoplastic polymer of the polymer layer of the elongate shaft is disposed about at least a portion of the heat conductive coil.
21. The catheter assembly of claim 16 , wherein the thermoplastic polymer is a shape memory polymer.
22. The catheter assembly of claim 16 , wherein the body temperature is about 37° C.
23. The catheter assembly of claim 16 , wherein the pre-selected glass transition temperature (Tg) is greater than about 37° C.
24. The catheter assembly of claim 16 , wherein the pre-selected glass transition temperature (Tg) is between about 50° C. and about 80° C.
25. The catheter assembly of claim 16 , wherein the pre-selected glass transition temperature (Tg) is between about 60° C. and about 70° C.
26. The catheter assembly of claim 16 , wherein the outer tubular member is a micromachined metallic tube including a plurality of apertures.
27. The catheter assembly of claim 17 , wherein the heat conductive member transfers thermal energy to the thermoplastic polymer.
28. The catheter of claim 1 wherein there is no intervening layer between the polymer layer thermoplastic polymer and the heat conductive member.
29. The catheter of claim 16 wherein there is no intervening layer between the polymer layer thermoplastic polymer and the heat conductive member.