Implantable medical device affixed internally within the gastrointestinal tract

• US 6,754,536 B2
• Filed: 01/30/2002
• Issued: 06/22/2004
• Est. Priority Date: 01/31/2001
• Status: Active Grant

• Current Assignee: A &P Marketing & Development, LLC, Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Swoyer, John M., Starkebaum, Warren
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US10/059,533
• Publication Number:
  US 20020103424A1
• Time in Patent Office: 874 Days
• Field of Search: 607/40
• US Class Current: 607/40
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/392 Detecting gastrointestinal contractions
• CPC Class Codes: A61B 5/42 Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems A61B1/00, A61B5/4857, A61B5/486, A61B5/4866, A61B5/4869 take precedence
• CPC Class Codes: A61B 5/4238 stomach
• CPC Class Codes: A61N 1/0517 Esophageal electrodes

Abstract

A GI tract stimulator and/or monitor IMD comprising a housing enclosing electrical stimulation and/or monitoring circuitry and a power source and an elongated flexible member extending from the housing to an active fixation mechanism adapted to be fixed into the GI tract wall is disclosed. After fixation is effected, the elongated flexible member bends into a preformed shape that presses the housing against the mucosa so that forces that would tend to dislodge the fixation mechanism are minimized. The IMD is fitted into an esophageal catheter lumen with the fixation mechanism aimed toward the catheter distal end opening whereby the bend in the flexible member is straightened. The catheter body is inserted through the esophagus into the GI tract cavity to direct the catheter distal end to the site of implantation and fix the fixation mechanism to the GI tract wall. The IMD is ejected from the lumen, and the flexible member assumes its bent configuration and lodges the hermetically sealed housing against the mucosa. A first stimulation/sense electrode is preferably an exposed conductive portion of the housing that is aligned with the bend of the flexible member so that it is pressed against the mucosa. A second stimulation/sense electrode is located at the fixation site.

Claims

1. A gastrointestinal implantable medical device adapted to be implanted within the GI tract and affixed to the mucosa or sub-mucosal layers of the GI tract wall comprising:

a hermetically sealed housing enclosing circuitry and a power source;

an elongated flexible member fixed at a member fixed end to the housing and extending away from the housing to a member free end supporting an active fixation mechanism for attachment to the mucosa or sub-mucosal layers of the GI tract wall; and

bending means incorporated with the elongated flexible member for bending the elongated member when unrestrained to press the housing against the mucosa so that forces that would tend to dislodge the fixation mechanism are minimized.

2. The implantable medical device of claim 1, wherein the fixation mechanism is formed of a material that dissolves in body fluids over a period of time to release the implantable medical device.

3. The implantable medical device of claim 1, wherein the free end of the elongated flexible member comprises an electrode head supporting the active fixation mechanism and supporting a stimulation/sense electrode and an electrical conductor extending from the stimulation/sense electrode to the circuitry within the hermetically sealed housing.

4. The implantable medical device of claim 3, wherein the electrode head comprises a plate, and the active fixation mechanism comprises a helix affixed to extend from the plate and adapted to be screwed into the mucosa or sub-mucosa layers.

5. The implantable medical device of claim 3, wherein the electrode head comprises a plate, and the active fixation mechanism comprises a hook affixed to extend from the plate and adapted to be pushed into the mucosa or sub-mucosa layers.

6. The implantable medical device of claim 3, further comprising a housing stimulation/sense electrode formed on the housing in alignment with the bending means such that the bending of the bending means presses the housing stimulation/sense electrode against the mucosa.

7. The implantable medical device of claim 1, wherein the free end of the elongated flexible member comprises an electrode head supporting a combined active fixation mechanism and stimulation/sense electrode and an electrical conductor extending from the stimulation/sense electrode to the circuitry within the hermetically sealed housing.

8. The implantable medical device of claim 7, wherein the electrode head comprises a plate, and the active fixation mechanism comprises a helix affixed to extend from the plate and adapted to be screwed into the mucosa or sub-mucosa layers.

9. The implantable medical device of claim 7, wherein the electrode head comprises a plate, and the active fixation mechanism comprises a hook affixed to extend from the plate and adapted to be pushed into the mucosa or sub-mucosa layers.

10. The implantable medical device of claim 7, further comprising a housing stimulation/sense electrode formed on the housing in alignment with the bending means such that the bending of the bending means presses the housing stimulation/sense electrode against the mucosa.

11. The implantable medical device of claim 1, wherein the electrode head comprises a plate, the attachment mechanism extends from the plate to engage the GI tract wall and inhibit dislodgement of the stimulation/sense electrode from operative contact with the GI tract wall, and the plate inhibits further advancement of the active fixation mechanism and perforation of the GI tract wall.

12. The implantable medical device of claim 1, wherein:

the free end of the elongated flexible member comprises an electrode head supporting the active fixation mechanism and supporting a stimulation/sense electrode and an electrical conductor extending from the stimulation/sense electrode to the circuitry within the hermetically sealed housing; and

the circuitry comprises an electrical stimulation generator that supplies electrical stimulation of the GI tract wall through the stimulation/sense electrode.

13. The implantable medical device of claim 12, wherein the circuitry comprises sensing means for sensing electrical signals of the GI tract through the stimulation/sense electrode.

14. The implantable medical device of claim 1, wherein:

the free end of the elongated flexible member comprises an electrode head supporting the active fixation mechanism and supporting a stimulation/sense electrode and an electrical conductor extending from the stimulation/sense electrode to the circuitry within the hermetically sealed housing; and

the circuitry comprises sensing means for sensing electrical signals of the GI tract through the stimulation/sense electrode.

15. The implantable medical device of claim 1, wherein:

the housing supports a first stimulation/sense electrode coupled with the circuitry in the housing in alignment with the bending means such that the bending of the bending means presses the housing stimulation/sense electrode against the mucosa.

the free end of the elongated flexible member comprises an electrode head supporting the active fixation mechanism and supporting a second stimulation/sense electrode and an electrical conductor extending from the stimulation/sense electrode to the circuitry within the hermetically sealed housing; and

the circuitry comprises an electrical stimulation generator that supplies electrical stimulation of the GI tract wall through the first and second stimulation/sense electrodes.

16. The implantable medical device of claim 1, wherein:

the housing supports a first stimulation/sense electrode coupled with the circuitry in the housing in alignment with the bending means such that the bending of the bending means presses the housing stimulation/sense electrode against the mucosa.

the free end of the elongated flexible member comprises an electrode head supporting the active fixation mechanism and supporting a second stimulation/sense electrode and an electrical conductor extending from the stimulation/sense electrode to the circuitry within the hermetically sealed housing; and

the circuitry comprises an electrical signal monitor that detects electrical signals of the GI tract wall through the first and second stimulation/sense electrodes.

17. The implantable medical device of claim 1, further comprising a housing stimulation/sense electrode formed on the housing in alignment with the bending means such that the bending of the bending means presses the housing stimulation/sense electrode against the mucosa.

18. The implantable medical device of claim 1, wherein an anti-inflammatory material selected from the group consisting of steroids, anti-bacterial agents, baclofen, dexamethasone sodium phosphate or beclomethasone phosphate is incorporated into the electrode head or fixation mechanism.

19. The implantable medical device of claim 1, wherein:

the member free end comprises a plate; and

the active fixation mechanism comprises a helix comprising one or more coil turn extending from a helix fixed end and a helix free end and having a helix axis, the helix fixed end supported at the plate to extend the helix axis orthogonally to the plate, the helix free end adapted to penetrate through the mucosa and the helix adapted to advance into the muscularis externa upon rotation of the helix until the plate is drawn against the mucosa.

20. The implantable medical device of claim 19, wherein the helix has an axial length enabling a depth of penetration from the plate in the range of 1 mm to 15 mm when the site comprises the antrum of the stomach wall or in the range of 1 mm to 10 mm when the site comprises corpus or fundus of the stomach wall to ensure that the helix free end does not extend substantially through the stomach wall.

21. The implantable medical device of claim 19, wherein a stimulation/sense electrode is supported on the plate of the electrode head to press against the mucosa when the plate is drawn against the mucosa.

22. The implantable medical device of claim 1, wherein:

the member free end comprises a plate; and

the active fixation mechanism comprises a hook comprising a hook shaft extending from a hook fixed end attached to an electrode head to a hook free end spaced from the plate, a sharpened tip formed at the hook free adapted to penetrate through the mucosa and to advance into the muscularis externa when insertion force is applied to the electrode head until the plate is drawn against the mucosa, whereupon advancement of the hook free end is halted.

23. The implantable medical device of claim 22, wherein the hook has an axial length enabling a depth of penetration from the plate in the range of 1 mm to 15 mm when the site comprises the antrum of the stomach wall or in the range of 1 mm to 10 mm when the site comprises corpus or fundus of the stomach wall to ensure that the hook free end does not extend substantially through the stomach wall.

24. The implantable medical device of claim 22, wherein a stimulation/sense electrode is supported on the plate of the electrode head to press against the mucosa when the plate is drawn against the mucosa.

25. The implantable medical device of claim 1, further comprising a physiologic sensor for sensing a physiologic state of the GI tract.

26. A method of implanting a gastrointestinal implantable medical device (IMD) within the gastrointestinal tract (GI tract) comprising:

forming the IMD with a hermetically sealed housing having a housing axis enclosing circuitry and a power source and with an elongated flexible member fixed at a member fixed end to the housing and extending away from the housing to a member free end supporting an active fixation mechanism, the elongated flexible member incorporating a bendable beam that imparts a bend in the elongated member to bend the active fixation mechanism out of axial alignment with the housing when unrestrained;

inserting the IMD into the lumen of an esophageal catheter body thereby restraining the flexible member and substantially reducing the bend;

advancing the esophageal catheter body through the esophagus to locate the active fixation mechanism at an attachment site of the GI tract wall within the GI tract;

fixing the active fixation mechanism to the GI tract wall at the attachment site; and

ejecting the IMD from the esophageal catheter lumen to enable the formation of the bend in the elongated flexible member to press the housing against the GI tract wall so that forces that would tend to dislodge the fixation mechanism are minimized.

27. The method of claim 26, wherein the active fixation mechanism comprises a helix adapted to be screwed into the mucosa or sub-mucosal layers of the GI tract, and the esophageal catheter body and the housing are shaped to mutually engage and inhibit rotation of the housing within the catheter body lumen, and wherein:

the fixing step comprises rotating the catheter body and the IMD to screw the helix into the mucosa or sub-mucosal layers of the GI tract

28. A system for implanting a gastrointestinal implantable medical device (IMD) within the gastrointestinal tract (GI tract) comprising:

an IMD formed with a hermetically sealed housing having a housing axis enclosing circuitry and a power source and with an elongated flexible member fixed at a member fixed end to the housing and extending away from the housing to a member free end supporting an active fixation mechanism, the elongated flexible member incorporating a bendable beam that imparts a bend in the elongated member to bend the active fixation mechanism out of axial alignment with the housing when unrestrained;

an esophageal catheter having an esophageal catheter body and catheter lumen into which the IMD is insertable whereupon the flexible member is restrained and the bend in the flexible member is substantially reduced, the esophageal catheter body adapted to be advanced through the esophagus to locate the active fixation mechanism at an attachment site of the GI tract wall within the GI tract;

means for fixing the active fixation mechanism to the GI tract wall at the attachment site; and

means for ejecting the IMD from the esophageal catheter lumen to enable the formation of the bend in the elongated flexible member to press the housing against the GI tract wall so that forces that would tend to dislodge the fixation mechanism are minimized.

29. The system of claim 28, wherein the esophageal catheter body and the housing are shaped to mutually engage and inhibit rotation of the housing within the catheter body lumen.

30. The system of claim 28, wherein the active fixation mechanism comprises a helix adapted to be screwed into the mucosa or sub-mucosal layers of the GI tract, and the esophageal catheter body and the housing are shaped to mutually engage and inhibit rotation of the housing within the catheter body lumen, whereby the catheter body and the IMD are rotatable to screw the helix into the mucosa or sub-mucosal layers of the GI tract.