CATHETER TIP DISPLACEMENT MECHANISM

• US 20080147000A1
• Filed: 12/13/2006
• Published: 06/19/2008
• Est. Priority Date: 12/13/2006
• Status: Active Grant

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Seibel, Eric J., Reinhall, Per G.
• Granted Patent: US 7,879,004 B2
• Time in Patent Office: Days
• US Class Current: 604/98.01
• CPC Class Codes: A61M 2025/0058 having an electroactive polymer material, e.g. for steering purposes, for control of flexibility, for locking, for opening or closing
• CPC Class Codes: A61M 25/0141 having flexible regions as a result of using materials with different mechanical properties
• CPC Class Codes: A61M 25/0155 with hydraulic or pneumatic means, e.g. balloons or inflatable compartments
• CPC Class Codes: A61M 25/0158 with magnetic or electrical means, e.g. by using piezo materials, electroactive polymers, magnetic materials or by heating of shape memory materials

Abstract

A distal end of a flexible catheter can be selectively deflected in a desired direction by actuating one or more actuators that extend outwardly of an exterior surface of the catheter. Each actuator can be a balloon disposed within a non-extendible balloon or sheath. Inflation of one (or both) of the balloon and the non-extendible balloon with a pressurized fluid can deflect the distal tip of the catheter. Another actuator embodiment comprises a strip of a bimorph material that bends outwardly when actuated, e.g., by heat, applying a force against adjacent tissue to deflect the distal tip. Yet another embodiment includes a strip of material that shortens when heated and can be coupled to a balloon that is inflated outwardly to increase a radial moment arm of the force applied thereby, relative to a neutral axis of the catheter, to more readily deflect the distal tip.

Claims

1. A catheter having a distal tip that can be selectively deflected in a desired direction, comprising:

(a) an elongate flexible shaft having a distal end where the distal tip of the catheter is disposed, a proximal end, and an outer surface;

(b) an actuator, at least a portion of which is disposed both proximate and externally to the outer surface prior to being selectively deflected, and which is selectively actuatable to provide a directed force that causes the distal end of the catheter to deflect in the desired direction; and

(c) a source of energy for selectively actuating the actuator to deflect the distal end in the desired direction.

2. The catheter of claim 1, wherein the actuator comprises a bimorph actuator that has two shape configurations, including a first configuration in which the bimorph actuator is radially compact, and a second configuration in which the bimorph actuator extends radially outwardly from the outer surface of the elongate flexible shaft.

3. The catheter of claim 2, wherein the bimorph actuator comprises a material selected from the group consisting of:

(a) a shape memory alloy;

(b) a piezo-composite;

(c) a plurality of dissimilar materials having substantially different coefficients of thermal expansion, bonded together;

(d) a shape memory polymer; and

(e) an electro-active polymer.

4. The catheter of claim 1, further comprising a sheath that covers the actuator, so that in the second configuration, the bimorph actuator applies the directed force against an interior surface of the sheath, which is configured to transfer the force to any adjacent anatomical structure within a body of a patient, so as to deflect the distal end of the elongate flexible shaft away from the adjacent anatomical structure in the desired direction, the sheath providing a smooth surface to facilitate advancement and withdrawal of the catheter through a body lumen.

5. The catheter of claim 4, wherein the sheath comprises a non-extendible balloon that is disposed around the outer surface of the elongate flexible shaft, encompassing the actuator.

6. The catheter of claim 1, wherein the actuator comprises a non- extendible balloon, further comprising at least one lumen that extends proximally through the elongate flexible shaft, and wherein the source of energy for selectively actuating the non-extendible balloon comprises a source of a pressurized fluid, further comprising a valve for selectively controlling supply of the pressurized fluid to the non-extendible balloon through the at least one lumen, for applying the force to deflect the distal end of the elongate flexible shaft in the desired direction.

7. The catheter of claim 6, wherein the actuator further comprises a deflector disposed on the outer surface of the elongate flexible shaft and enclosed by the balloon, the deflector initiating bending of the distal end of the elongate flexible shaft in the desired direction by at least initially pushing outwardly against an inner surface of the non-extendible balloon when the pressurized fluid is being applied to a volume formed between the inner surface of the non-extendible balloon and the outer surface of the elongate flexible shaft.

8. The catheter of claim 7, wherein the deflector comprises a balloon and wherein a lumen is included within the elongate flexible shaft for conveying the pressurized fluid from the source to selectively inflate the balloon so that it extends outwardly from the outer surface of the elongate flexible shaft to at least initially push against the inner surface of the non-extendible balloon.

9. The catheter of claim 6, wherein the actuator is attached to a non-extendible balloon and extends in a direction generally parallel to a longitudinal axis of the elongate flexible shaft, the actuator being selectively energizable while the non-extendible balloon is selectively inflated so that the actuator is then disposed radially further away from a neutral axis of the elongate flexible shaft, the actuator shortening in length when actuated to apply a force to the elongate flexible shaft through the non-extendible balloon that is inflated, the force deflecting the distal end of the elongate flexible shaft in the desired direction.

10. The catheter of claim 1, wherein the actuator comprises an elongate strip of a material that changes shape when selectively actuated, the elongate strip of material being attached to the outer surface of the elongate flexible shaft at opposite ends and when actuated, changing shape so that portion of the elongate strip of material disposed between the opposite ends moves outwardly away from the outer surface of the elongate flexible shaft, causing the distal end of the elongate flexible shaft to deflect in the desired direction.

11. The catheter of claim 1, further comprising:

(a) a balloon that is configured to expand around the outer surface of the elongate flexible shaft and which is disposed proximal of the actuator; and

(b) a lumen extending through at least a portion of the elongate flexible shaft for conveying a pressurized fluid from a source to inflate the balloon so that a diameter of the balloon increases sufficiently to contact an adjacent anatomical structure within a body of a patient, the balloon that is thus inflated exerting a force on the adjacent anatomical structure that stabilizes the catheter relative to the adjacent anatomical structure while the distal end of the elongate flexible shaft is being deflected in the desired direction.

12. The catheter of claim 1, further comprising a mother scope that extends generally from the proximal end of the catheter and includes a distal end that is disposed at an intermediate position along a length of the catheter, and a daughter scope that extends distally from the distal end of mother scope, wherein the daughter scope includes the distal end of the elongate flexible shaft, and the actuator to selectively deflect the distal end of the daughter scope.

13. The catheter of claim 1, further comprising a mother scope that extends generally from the proximal end of the catheter and includes a distal end that is disposed at an intermediate position along a length of the catheter, and a daughter scope that extends distally from the distal end of mother scope, wherein the mother scope includes another actuator that is selectively coupled to the source of energy, to selectively deflect the distal end of the mother scope.

14. The catheter of claim 1, wherein the elongate shaft is rotatable about its longitudinal axis, to position the actuator in a desired orientation so when selectively actuated, the actuator deflects the distal tip of the catheter in the desired direction.

15. The catheter of claim 1, wherein the distal tip includes an imaging device that produces an image used for visualizing a pathway along which the catheter is being advanced.

16. A catheter having a distal tip that can be selectively deflected in a desired direction, comprising:

(a) an elongate flexible shaft having a distal end where the distal tip of the catheter is disposed, a proximal end, and an outer surface;

(b) a plurality of actuators, at least a portion of each actuator being disposed externally of the outer surface, at circumferentially spaced-apart positions prior to being selectively deflected, and being selectively actuatable to provide a directed force that causes the distal end of the catheter to deflect in the desired direction; and

(c) a source of energy for selectively actuating one or more the plurality of actuators to deflect the distal end in the desired direction.

17. The catheter of claim 16, wherein each of the plurality of actuators comprises a bimorph actuator that has two shape configurations, including a first configuration in which the bimorph actuator is radially compact, and a second configuration in which the bimorph actuator extends radially outwardly from the outer surface of the elongate flexible shaft.

18. The catheter of claim 17, wherein each bimorph actuator comprises a material selected from the group consisting of:

(a) a shape memory alloy;

(b) a piezo-composite;

(c) a plurality of dissimilar materials having substantially different coefficients of thermal expansion, bonded together;

(d) a shape memory polymer; and

(e) an electro-active polymer.

19. The catheter of claim 17, further comprising a sheath that covers the plurality of actuators, so that in the second configuration, each bimorph actuator that is selectively activated applies the directed force against an interior surface of the sheath, which is configured to transfer the force to any adjacent anatomical structure within a body of a patient, so as to deflect the distal end of the elongate flexible shaft away from the adjacent anatomical structure in the desired direction, the sheath providing a smooth surface to facilitate advancement and withdrawal of the catheter through a body lumen.

20. The catheter of claim 19, wherein the sheath comprises a non-extendible balloon that is disposed around the outer surface of the elongate flexible shaft, encompassing the plurality of actuators.

21. The catheter of claim 16, wherein each of the plurality of actuators comprises a non-extendible balloon, further comprising a plurality of lumens that extend proximally through the elongate flexible shaft, and wherein the source of energy for selectively actuating each non-extendible balloon comprises a source of a pressurized fluid, further comprising a valve for selectively controlling supply of the pressurized fluid to each non-extendible balloon, for applying the force to deflect the distal end of the elongate flexible shaft in the desired direction.

22. The catheter of claim 21, wherein each of the plurality of actuators further comprises a deflector disposed on the outer surface of the elongate flexible shaft and enclosed by the balloon, the deflector initiating bending of the distal end of the elongate flexible shaft in the desired direction by at least initially pushing outwardly against an inner surface of the non-extendible balloon when the pressurized fluid is being applied to a volume formed between the inner surface of the non-extendible balloon and the outer surface of the elongate flexible shaft.

23. The catheter of claim 22, wherein the deflector comprises a balloon and wherein a lumen is included within the elongate flexible shaft for conveying the pressurized fluid from the source to selectively inflate the balloon so that it extends outwardly from the outer surface of the elongate flexible shaft to at least initially push against the inner surface of the non-extendible balloon.

24. The catheter of claim 16, wherein each actuator comprises an elongate strip of a material that changes shape when selectively actuated, the elongate strip of material being attached to the outer surface of the elongate flexible shaft at opposite ends and when actuated, changing shape so that portion of the elongate strip of material disposed between the opposite ends moves outwardly away from the outer surface of the elongate flexible shaft, causing the distal end of the elongate flexible shaft to deflect in the desired direction.

25. The catheter of claim 21, wherein each of the plurality of actuators is attached to a different non-extendible balloon and extends in a direction generally parallel to a longitudinal axis of the elongate flexible shaft, each actuator being selectively energizable while the non-extendible balloon to which the actuator is attached is selectively inflated so that the actuator is then disposed radially further away from a neutral axis of the elongate flexible shaft, the actuator shortening in length when actuated to apply a force to the elongate flexible shaft through the non-extendible balloon that is inflated, the force deflecting the distal end of the elongate flexible shaft in the desired direction.

26. The catheter of claim 16, further comprising:

(a) a balloon that is configured to expand around the outer surface of the elongate flexible shaft and is disposed proximal of the plurality of actuators; and

(b) a lumen extending through at least a portion of the elongate flexible shaft for conveying a pressurized fluid from a source to inflate the balloon so that a diameter of the balloon increases sufficiently to contact an adjacent anatomical structure within a body of a patient, the balloon that is thus inflated exerting a force on the adjacent anatomical structure that stabilizes the catheter relative to the adjacent anatomical structure while the distal end of the elongate flexible shaft is being deflected in the desired direction.

27. The catheter of claim 16, further comprising a mother scope that extends generally from the proximal end of the catheter and includes a distal end that is disposed at an intermediate position along the catheter, and a daughter scope that extends distally from the distal end of mother scope, wherein the daughter scope includes the distal end of the elongate flexible shaft, and the plurality of actuators to selectively deflect the distal end of the daughter scope.

28. The catheter of claim 16, further comprising a mother scope that extends generally from the proximal end of the catheter and includes a distal end that is disposed at an intermediate position along a length of the catheter, and a daughter scope that extends distally from the distal end of mother scope, wherein the mother scope includes another plurality of actuators, each of which is selectively coupled to the source of energy, to selectively deflect the distal end of the mother scope in a desired direction.

29. The catheter of claim 16, wherein the distal tip includes an imaging device for producing an image used to visualize a pathway along which the catheter is being advanced.

30. Apparatus for controllably selectively deflecting a distal tip of a catheter in a desired direction, comprising:

(a) a collar configured to be separate and distinct from the catheter and to be disposed around the outer surface of a catheter, adjacent to a distal tip of the catheter; and

(b) a plurality of actuators, configured to be separate and distinct from the collar and disposed on the collar, each actuator of the plurality of actuators being selectively actuatable to produce a directed force outwardly of the collar to deflect a distal dip of a catheter in a desired direction.

31. The apparatus of claim 30, further comprising means for selectively actuating each actuator disposed on the collar to produce the directed force.

32. The apparatus of claim 30, wherein each of the plurality of actuators comprises a bimorph actuator that is selectively actuated to change between two shape configurations, a first configuration of the bimorph actuator being substantially more radially compact relative to the collar than a second configuration, the bimorph actuator being thus adapted to produce the directed force when actuated to change from the first configuration to the second configuration.

33. The apparatus of claim 32, wherein each bimorph actuator comprises a material selected from the group consisting of:

(a) a shape memory alloy;

(b) a piezo-composite;

(c) a plurality of dissimilar materials having substantially different coefficients of thermal expansion, bonded together;

(d) a shape memory polymer; and

(e) an electro-active polymer.

34. The apparatus of claim 32, further comprising a sheath that covers the plurality of actuators, so that in the second configuration, each bimorph actuator that is selectively activated applies the directed force against an interior surface of the sheath, which is configured to apply the directed force to any adjacent anatomical structure within a body of a patient, so as to deflect a distal tip of a catheter away from the adjacent anatomical structure in the desired direction, the sheath providing a smooth surface to facilitate advancement and withdrawal of a catheter through a body lumen.

35. The apparatus of claim 34, wherein the sheath comprises a non-extendible balloon that is disposed around the plurality of actuators.

36. The apparatus of claim 30, further comprising electrical contacts disposed on the collar and configured to couple to corresponding electrical contacts on a catheter for coupling an electrical current to each of the plurality of actuators, the electrical current being selectively applied to an actuator to actuate it.

37. The apparatus of claim 30, further comprising a plurality of pliable members that are each relatively substantially softer than the plurality of actuators, a pliable member being disposed over an end of each actuator to minimize damage to tissue against which the directed force is applied to deflect a distal tip of a catheter.

38. A method for selectively deflecting a distal tip of a catheter in a desired direction, comprising the steps of:

(a) providing a plurality of actuators disposed at circumferentially-spaced apart positions around an outer surface of the catheter, wherein at least a portion of each of the plurality of actuators is disposed externally of an outer surface of the catheter prior to being actuated; and

(b) selectively actuating at least one of the plurality of actuators to produce a directed force that deflects the distal tip of the catheter in the desired direction, the directed force being developed externally of an outer surface of the catheter.

39. The method of claim 38, wherein the step of selectively actuating comprises the step of applying an electrical current to a bimorph actuator comprising each of the plurality of actuators that is to be actuated.

40. The method of claim 39, wherein each bimorph actuator, when actuated, changes between a first configuration and a second configuration, the second configuration applying the directed force so as to deflect the distal tip of the catheter.

41. The method of claim 40, wherein the bimorph actuators bend radially outwardly when actuated to change from the first configuration to the second configuration.

42. The method of claim 41, wherein when in the second configuration, the bimorph actuators are adapted to apply the directed force against an anatomical structure within a body of a patient, biasing the distal tip of the catheter to generally deflect in an opposite direction from that in which the directed force is applied.

43. The method of claim 38, further comprising the step of encompassing the plurality of actuators in a protective sheath that facilitates insertion and withdrawal of the catheter through a body lumen.

44. The method of claim 38, wherein each of the plurality of actuators comprises a strip of an elongate strip that extends longitudinally along the catheter, proximate to the outer surface of the catheter, the elongate strip comprising a material that changes state when heated, and wherein the step of selectively actuating comprises the step of selectively applying an electrical current to the at least one actuator to cause the elongate strip to compress axially as the material from which it is made changes from one state to another in response to heating caused by the electrical current.

45. The method of claim 38, further comprising the step of producing an image of a pathway along which the catheter is being advance to assist in determining which of the plurality of actuators to selectively actuate.