WO2005018708A2

WO2005018708A2 - Magnetic circumferentially coupled implantable pump

Info

Publication number: WO2005018708A2
Application number: PCT/US2004/026781
Authority: WO
Inventors: Daniel R. Burnett
Original assignee: Theranova, Llc
Priority date: 2003-08-19
Filing date: 2004-08-18
Publication date: 2005-03-03
Also published as: WO2005018708A3

Abstract

A magnetic circumferentially-coupled implantable pump (9) is disclosed herein. A magnetically coupled implantable actuation system utilizes a magneticallyt-coupled drive mechanism (4) configured to generate power for implantable medical devices. One variation generally comprise a drive magnet (25) having a first radius and adapted to rotate about a longitudinal axis when urged, and a driven magnet (26) defining a second radius, which is less than the first radius. This driven magnet is adapted to be implanted within a body rotate about the longitudinal axis when coaxially positioned within a receiving cavity defined by the drive magnet such that magnetic coupling occurs circurnferentially between the driven magnet and the drive magnet. Another variation utilizes elongate bar magnets (1, 5) configured to rotate about a pivot. An optional anchor (12) can be used to secure the implanted driven magnet housing against any rotational forces or moments by securing the housing within the subcutaneous layer.

Description

TITLE OF THE INVENTION MAGNETIC CIRCUMFERENTIALLY COUPLED IMPLANTABLE PUMP

Daniel R. Burnett

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefits of priority to U.S. Provisional Patent

Application Serial No. 60/495,946 filed August 19, 2003 and is a continuation-in-part of U.S. Patent Application Serial No. 10/700,863, filed November 3, 2003, which claims the benefits of priority to U.S. Provisional Patent Application Serial No. 60/496,441, filed August 21, 2003. Each of the aforementioned applications is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION [0002] The present invention relates to implantable medical devices. More particularly, the present invention relates to subcutaneously implantable drive mechanisms, such pumps, which may be magnetically coupled to an external drive mechanism.

BACKGROUND OF THE INVENTION [0003] In the field of medicine, more and more electronic devices are being implanted in the human body for both acute and chronic conditions. For chronic conditions, or acute conditions with large power demands, the need for power frequently is greater than that which can be provided with a single battery. In these cases, a revision surgery is frequently required in order to replace the depleted battery, placing the patient at risk for the various complications associated with surgery and increasing costs to the healthcare system. In order to combat this problem, advances have been made in the field of magnetically coupled, externally powered devices. [0004] Some conventional magnetically-coupled drive mechanisms are generally comprised of two components, i.e., an external drive magnet and an implantable driven magnet, each employing a single magnet coliineariy aligned along their rotational axes. Moreover, many conventional magnetically-coupled drive mechanisms detail the use of static magnets. [0005] Other conventional devices have generally employed magnetically-coupled pumps which are non-collinearly aligned to transfer energy across the skin through magnetic coupling. These devices, however, fail to provide for firm engagement of the magnetic poles of its magnets and instead relies upon the interaction of sequentially oscillating fields with less reliability in transferring driving forces against any resistance. [0006] Conventional devices in transdermal power generation and transdermal pump power generation appears to have been limited, instead, to low-power devices which may not be optimized for the transdermal transfer of power. SUMMARY OF THE INVENTION [0007] A magnetically coupled implantable actuation system may utilize a magnetically-coupled drive mechanism configured to generate power for implantable medical devices. One variation of the actuation system may generally comprise a drive magnet forming at least two opposed elongate members adapted to rotate about a pivot when urged, and a driven magnet adapted to be implanted within a body, the driven magnet forming at least two opposed elongate members adapted to magnetically couple over a distance in a complementary manner with the elongate members of the drive magnet. [0008] An alternative variation of the actuation system may generally comprise a drive magnet having a first radius and adapted to rotate about a longitudinal axis when urged, and a driven magnet defining a second radius, which is less than the first radius, and adapted to be implanted within a body, wherein the driven magnet is adapted to rotate about the longitudinal axis when coaxially positioned within a receiving cavity defined by the drive magnet such that magnetic coupling occurs circumferentially between the driven magnet and the drive magnet. [0009] If the magnets are formed as bar magnets, a dipole bar magnet may be used as the driving magnet for urging or driving a corresponding magnet implanted within a body. The bar magnet may be positioned or encased within a housing and allowed to rotate freely about a drive shaft. The bar magnet may be configured in this variation as an elongate member having opposing magnetic poles defined on either end of the member. The drive shaft may be located at or near the mid-point of the bar magnet to ensure that it is rotationally balanced when rotated about the drive shaft. The driving magnet unit may be magnetically coupled to an implanted driving mechanism which may be used to provide energy or power to an implanted pump or generator. The implanted driven unit may be implanted below the skin in the subcutaneous layer. The driven unit may be implanted deeper below the skin but it is preferably positioned sufficiently close to the skin surface such that the driving unit may be positioned in proximity to the driven unit to allow the externally located bar magnet and implanted bar magnet to magnetically couple through skin. [0010] The driving magnet may be urged or driven rotationally around a drive-shaft via an input torque provided by a motor or some other actuator coupled to a driving unit. The motor or actuator may itself be powered through various devices and methods, e.g., batteries, connection to a conventional power outlet or power generator, etc. As the magnet is rotated, the implanted magnet is also driven around its drive-shaft to create a corresponding output torque. The rotational forces of the implanted drive-shaft may then transfer the torque energy to an implanted medical device, such as a pump and/or power generator, to power its operation. [0011] Another variation may have an external driver unit circumferentially positionable about an implantable pump unit. The driven pump magnet(s) and drive magnet(s) may be coplanarly positionable relative to one another such that when the two units are coupled to one another between the patient's skin, the pump magnets may be concentrically positioned within the circumference of the drive magnets. This positioning for the transferal of power results in a circumferential interaction with the pump sitting directly between (or orthogonal in relation to) the drive magnets. The external surface of a housing, within which the support members for holding and/or positioning the drive magnets, is disposed, may rest against the skin when coupled to transfer energy. An implanted pump may be designed to rest between the external drive magnets so that the area above the pump is not subjected to axial loads as in the case of collinear designs. [0012] The pump magnets may be configured as a continuous circularly-shaped magnet having regions of alternating polarity. Alternatively, the pump magnets may be comprised of multiple discrete magnets. In the same manner, the drive magnets may similarly be comprised of a continuous circularly-shaped magnet having regions of alternating polarity which correspond to the polarity of the pump magnets or as multiple discrete magnets. [0013] In any of the variations, an optional anchor may be configured to secure the implanted driven magnet housing against any rotational forces or moments which may be generated by the rotation of the internal magnet. The anchor, in one variation, may simply be configured as an extension having a tapered edge protruding from the unit for inhibiting movement of the unit and to help anchor it within the subcutaneous layer. Alternatively, the unit may simply be configured to be sutured through any number of eyelets or openings defined over the unit housing directly to the subcutaneous layer or to muscles or other structures below the skin. BRIEF DESCRIPTION OF THE DRAWINGS [0014] Figs. 1A and IB show top and side views, respectively, of one variation of a dipole, bar magnet variation for driving a pump. [0015] Fig. 2 shows a perspective view of another variation of a dipole magnet having a circumferential configuration. [0016] Figs. 3 A to 3C show side, top, and perspective views, respectively, of another variation having a multi-pole configuration. [0017] Figs. 4A and 4B show side and top views, respectively, of one variation of an externally located drive magnet having an optional external user display. [0018] Fig. 5 shows a side view of one variation for maintaining an external drive magnet against a patient' s body using an applicator belt. [0019] Figs. 6A and 6B show side and top views, respectively, of yet another variation of an external driver magnet circumferentially positionable about an implantable pump. [0020] Fig. 7 illustrates an example of the pump and driver assembly of Figs. 6A and 6B implanted within a patient body. [0021] Fig. 8 illustrates a variation of an implanted pump and driver assembly in which the pump may be configured with anchoring devices. DETAILED DESCRIPTION OF THE INVENTION [0022] As can be seen in Fig. 1A, which shows a top view of one variation of a dipole, bar magnet 1 within a housing 2, the dipole bar magnet 1 may be used as a driving magnet for urging or driving a corresponding magnet implanted within a body. The bar magnet 1 may be positioned or encased within a housing 2 and allowed to rotate freely about a drive shaft 3. The bar magnet 1 may be configured in this variation as an elongate member having opposing magnetic poles defined on either end of the member. The drive shaft 3 is preferably located at or near the mid-point of bar magnet 1 to ensure that bar magnet 1 is rotationally balanced when rotated about drive shaft 3 in the direction of the arrows shown in the figure. Bar magnet 1, as well as in other variations below, may be made from various ferromagnetic materials commonly known to those of skill in the art. Fig. IB shows a side view of the driving magnet unit magnetically coupled to an implanted driving mechanism which may be used to provide energy or power to an implanted pump or generator. The bar magnet 1, positioned within the externally located (relative to the patient body) driving unit 4, may be seen as aligning with a corresponding implanted bar magnet 5 located within the implanted magnetically driven unit 9. The implanted driven unit 9 may be implanted below skin 10 in the subcutaneous layer 11. Driven unit 9 may be implanted deeper below skin 10 of the patient, however, the driven unit 9 is preferably positioned sufficiently close to the skin 10 such that driving unit 4 may be positioned in proximity to driven unit 9 to allow externally located bar magnet 1 and implanted bar magnet 5 to magnetically couple through skin 10. [0023] In operation, driving unit 4 may be positioned adjacent to skin 10 or in proximity of driven unit 9 such that the poles of bar magnet 1 magnetically engage with the opposite poles of bar magnet 5. Bar magnet 1 may be urged or driven rotationally around its drive-shaft 3 via an input torque 6 which may be provided by a motor or some other actuator A coupled to driving unit 4. The motor or actuator A may itself be powered through various devices and methods, e.g., batteries, connection to a conventional power outlet or power generator, etc. As bar magnet 1 is rotated, the implanted magnet 5 is also driven around its drive-shaft 7 and creates a corresponding output torque 6' due to the interaction of the magnetic forces. The rotational forces 6' of the implanted drive-shaft 7 may then transfer the torque energy to an implanted medical device, such as a pump and/or power generator P, to power its operation. [0024] Also shown is one variation of an optional anchor 12 which may be configured to secure the implanted driven unit 9 against any rotational forces or moments which may be generated by the rotation of the internal magnet 5. Anchor 12 in one variation may simply be configured as an extension having a tapered edge protruding from the unit 9 for inhibiting movement of the unit 9 and to help anchor unit 9 within the subcutaneous layer 11. Alternatively, unit 9 may simply be configured to be sutured S through any number of eyelets or openings 12' defined over unit 9 directly to the subcutaneous layer 11 or to muscles or other structures below skin 10. [0025] Fig. 2 illustrates a perspective view of another variation of a driving unit and an implantable driven unit similar to that shown in Figs. 1 A and IB. However, this variation may utilize implanted magnet 13 and externally located driving magnet 14 as flattened disk- shaped magnets. Each of magnets 13, 14 may be circularly-shaped although other shapes, e.g., elliptical, rectangular, triangular, etc., shaped magnets may be configured provided that each magnet 13, 14 is preferably configured in a corresponding manner to one another. Each magnet 13, 14 may also define multiple poles around the magnet, if desired. [0026] Figs. 3 A to 3C illustrate side, top, and perspective views, respectively, of another variation having a multi-pole configuration. In this variation, the external driving unit and implanted drive unit are similar to the variations above. However, the internally implanted driven magnet 15 and externally located drive magnet 16 are configured in this variation as multi-pole bar magnets. The magnets 15, 16 are each shown in this variation as having four perpendicularly spaced-apart arm members of alternating polarity extending from shaft 3. Although four members are shown in this variation, an additional number of arm members may be incorporated provided that the arm members are properly spaced apart to rotate about the shaft 3 in a balanced manner. These multi-pole magnets 15, 16 serve to create a more powerful force over a larger surface area than with a single dipole magnet. [0027] Figs. 4 A and 4B illustrate side and top views, respectively, of one variation of an externally located driving unit 4 having an attached motor or actuator 18. Motor 18 may have an optional external user display/control 17 mounted on the motor unit 18. In this variation, motor 18 may be attached to the driving unit 4 and coupled to drive shaft 3 for transmitting power to the magnet 1 via its driveshaft 3. As seen in the top view of user display/control 17 in Fig. 4B, optional features for controlling and/or monitoring the driving unit 4 and implantable pump unit may include, e.g., a total flow meter 19 (for the power generation this may be a total energy meter), an indicator 20 to notify the user that the internal and external magnets are engaged, and an activation button 21 to initiate the rotation of the external magnet 1. These features may be omitted and other features may alternatively be included depending upon the information and/or feedback desired by the user. [0028] Fig. 5 shows a side view of one variation for maintaining an external drive unit 4 against a patient's body using, e.g., an applicator belt 22. In this variation, the external drive mechanism 4 may be attached onto a belt 22 or other strap that can be adjustably fastened 23 around the user to allow placement of the external drive unit 4 against a patient's body. Thus, the drive unit 4 may be positioned on the patient's body to be in proximity of the implanted unit so as to enable the engagement of the internal magnets without the need for continuous manipulation or securing of the device by hand. Alternatively, temporary adhesives may be employed along the external surfaces of the drive unit 4 to enable the direct adherence of the unit 4 directly against the skin of the patient. [0029] Figs. 6A and 6B show side and top views, respectively, of yet another variation of an external driver unit circumferentially positionable about an implantable pump unit. This variation may utilize the same or similar external user display/control 17 as described above. In this variation, however, the driven pump magnet(s) 26 and drive magnet(s) 25 are coplanarly positionable relative to one another such that when the two units are coupled to one another between the patient' s skin, the pump magnets 26 may be concentrically positioned within the circumference of the drive magnets 25. This positioning for the transferal of power results in a circumferential interaction with the pump sitting directly between (or orthogonal in relation to) the drive magnets 25. [0030] In this variation, the drive magnets 25 may be positioned at the distal end of a cylindrically-shaped support member 24 extending in a radial direction and a longitudinal direction relative to a longitudinal axis defined by the device. The support member 24 may extend within a housing into the cylindrically-shaped configuration to form a receiving area within which the pump magnets 26 and/or the pump 27 itself may be concentrically positioned. The external surface of the housing, within which the support member 24 is disposed, may rest against the skin when coupled to transfer energy. The implanted pump 27 may be designed to rest between the external drive magnets 26 so that the area above the pump 27 is not subjected to axial loads as in the case of collinear designs. The pump magnets 25 may be configured as a continuous circularly-shaped magnet having regions of alternating polarity. Alternatively, the pump magnets 25 may be comprised of multiple discrete magnets positioned at the distal end of support member 24. In the same manner, the drive magnets 25 may similarly be comprised of a continuous circularly-shaped magnet having regions of alternating polarity which correspond to the polarity of the pump magnets 25 or as multiple discrete magnets. [0031] Additional smaller magnets 28, 29 may be incorporated onto both the drive and pump units, respectively, which may be configured to correspondly interact with one another when positioned in proximity to sense the rotations of the pump magnets 26 and/or hold the pump housing 30 in place as the magnets 26 spin. In operation, the drive unit may be positioned in proximity to the implanted pump by positioning the driver over the patient's skin such that the implanted pump unit is surrounded by the support member 24 and drive magnets 25. As the motor torques the drive shaft 3 to actuate the rotation of the support member 24 and drive magnets 25, the pump magnets 26 may be urged to spin by the circumferential magnetic coupling between the drive magnets 25 and the pump magnets 26. The pump magnets 26 in turn may be coupled to the pump or generator 27 to either actuate fluid flow or to generate power. The fluid/power may then be transferred along the tubing/wiring 31, 32 to allow the implantable device to function. [0032] Fig. 7 illustrates an example of the coupled pump and driver assembly of Figs. 6A and 6B implanted within a patient body. As shown, the driver and pump can be seen in the implanted, engaged state with tenting of the skin 34 to allow for interaction of the magnets 25, 26. The pump may be placed in the subcutaneous space 35 above or anchored to the abdominal wall 36. [0033] Fig 8 illustrates another example of an implanted pump and driver assembly in which the pump may be configured with anchoring devices. As shown, the driver and pump units may be circumferentially coupled, as described above; however, in this variation, the pump unit may incorporate a variety of different configurations for anchors 12, as also described above. [0034] U.S. Patent Application Serial No. 10/369,550, filed on February 21, 2003, U.S. Provisional Patent Application Serial No.60/359,287, filed on February 25, 2002 and U.S . Provisional Patent Application Serial No. 60/389,346, filed on June 18, 2002 are all incorporated by reference in their entireties. [0035] The applications of the devices and systems discussed above are not limited to the variations shown. Modification of the above-described variations of the methods and mechanical aspects of the invention that are obvious to those of skill in the arts are intended to be within the scope of the claims. Moreover, various combinations of aspects between examples is also contemplated and is considered to be within the scope of this disclosure.

Claims

CLAIMS I claim: 1. A magnetically coupled implantable actuation system comprising: a drive magnet having a first radius and adapted to rotate about a longitudinal axis when urged; and a driven magnet defining a second radius, which is less than the first radius, and adapted to be implanted within a body, wherein the driven magnet is adapted to rotate about the longitudinal axis when coaxially positioned within a receiving cavity defined by the drive magnet such that magnetic coupling occurs circumferentially between the driven magnet and the drive magnet.

2. The actuation system of claim 1 further comprising an anchor located on a housing which encloses the driven magnet.

3. The actuation system of claim 2 wherein the anchor comprises at least one tapered edge protruding from the housing.

4. The actuation system of claim 2 wherein the anchor comprises sutures.

5. The actuation system of claim 1 further comprising a pump adapted to be implanted within the body, wherein the pump is coupled to the driven magnet and adapted to urge fluid when actuated by the driven magnet.

6. The actuation system of claim 1 further comprising a power generator adapted to be implanted within the body, wherein the power generator is coupled to the driven magnet and adapted to generate energy when actuated by the driven magnet.

7. The actuation system of claim 1 further comprising a sensor in electrical communication with the drive magnet.

8. The actuation system of claim 7 wherein the sensor is adapted to sense at least one fluid flow parameter.

9. The actuation system of claim 7 wherein the sensor is adapted to detect an engagement between the drive magnet and the driven magnet.

10. The actuation system of claim 1 wherein the drive magnet comprises a circularly-shaped magnet having regions of alternating polarity about a circumference of the drive magnet.

11. The actuation system of claim 1 wherein the drive magnet comprises a plurality of discrete magnets circumferentially positionable about the driven magnet, each of the discrete magnets having an alternating polarity.

12. The actuation system of claim 1 further comprising an actuator or motor rotationally coupled to the drive magnet.

13. The actuation system of claim 12 further comprising a display coupled to the actuator or motor.

14. The actuation system of claim 12 further comprising a control panel coupled to the actuator or motor.

15. The actuation system of claim 1 further comprising an adjustable strap for fastening the drive magnet to an external region of the body in proximity to the driven magnet.

16. The actuation system of claim 1 wherein the driven magnet is further adapted to be positioned co-planarly with the drive magnet.

17. A magnetically coupled implantable actuation system comprising: a drive magnet forming at least two opposed elongate members adapted to rotate about a pivot when urged; and a driven magnet adapted to be implanted within a body, the driven magnet forming at least two opposed elongate members adapted to magnetically couple over a distance in a complementary manner with the elongate members of the drive magnet.

18. The actuation system of claim 17 further comprising an anchor located on a housing which encloses the driven magnet.

19. The actuation system of claim 18 wherein the anchor comprises at least one tapered edge protruding from the housing.

20. The actuation system of claim 18 wherein the anchor comprises sutures.

21. The actuation system of claim 17 further comprising a pump adapted to be implanted within the body, wherein the pump is coupled to the driven magnet and adapted to urge fluid when actuated by the driven magnet.

22. The actuation system of claim 17 further comprising a power generator adapted to be implanted within the body, wherein the power generator is coupled to the driven magnet and adapted to generate energy when actuated by the driven magnet.

23. The actuation system of claim 17 further comprising a sensor in electrical communication with the drive magnet.

24. The actuation system of claim 23 wherein the sensor is adapted to sense at least one fluid flow parameter.

25. The actuation system of claim 23 wherein the sensor is adapted to detect an engagement between the drive magnet and the driven magnet.

26. The actuation system of claim 17 wherein the drive magnet has a shape selected from the group consisting of elongate rods, crosses, circles, ellipses, rectangles, and triangles.

27. The actuation system of claim 17 wherein the drive magnet comprises multiple poles perpendicularly spaced apart and having alternating polarities.

28. The actuation system of claim 17 further comprising an actuator or motor rotationally coupled to the drive magnet.

29. The actuation system of claim 28 further comprising a display coupled to the actuator or motor.

30. The actuation system of claim 28 further comprising a control panel coupled to the actuator or motor.

31. The actuation system of claim 17 further comprising an adjustable strap for fastening the drive magnet to an external region of the body in proximity to the driven magnet.