Retrievability for implantable medical devices

• US 10,328,272 B2
• Filed: 05/08/2017
• Issued: 06/25/2019
• Est. Priority Date: 05/10/2016
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Delanely, Jr., Joseph Thomas, Kane, Michael J., Haasl, Benjamin J., Frankson, Danielle
• Primary Examiner(s): Packard, Benjamin J
• Application Number:
  US15/589,642
• Publication Number:
  US 20170326373A1
• Time in Patent Office: 778 Days
• CPC Class Codes: A61L 2400/18 Modification of implant surfaces in order to improve biocompatibility, cell growth, fixation of biomolecules, e.g. plasma treatment
• CPC Class Codes: A61L 31/022 Metals or alloys
• CPC Class Codes: A61L 31/10 Macromolecular materials
• CPC Class Codes: A61L 31/14 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61N 1/0573 chacterised by means penetrating the heart tissue, e.g. helix needle or hook
• CPC Class Codes: A61N 1/362 Heart stimulators heart defibrillators A61N1/39
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators
• CPC Class Codes: C08L 71/02 Polyalkylene oxides

Abstract

An implantable medical device (IMD) may include an outer housing having a titanium outer surface, the titanium outer surface including a plurality of titanium atoms. A tissue growth-inhibiting layer may extend over the titanium outer surface. In some cases, the tissue growth-inhibiting layer may include a plurality of polyethylene glycol molecules, at least some of the plurality of polyethylene glycol molecules covalently bonded via an ether bond to one of the plurality of titanium atoms.

Claims

1. An implantable medical device (IMD), comprising:

an outer housing having a titanium outer surface;

the titanium outer surface comprising a plurality of titanium atoms;

a tissue growth-inhibiting layer extending over the titanium outer surface;

the tissue growth-inhibiting layer comprising a plurality of polyethylene glycol molecules, at least some of the plurality of polyethylene glycol molecules covalently bonded via an ether bond to one of the plurality of titanium atoms; and

wherein the tissue growth-inhibiting layer is formed by hydroxylating at least some of the plurality of titanium atoms and covalently bonding a plurality of hydroxyl-terminated polyethylene glycol molecules to the hydroxylated titanium atoms with a concomitant loss of water molecules.

2. The IMD of claim 1, wherein the titanium outer surface comprises an electrically active surface.

3. The IMD of claim 2, further comprising an electrically insulating layer disposed over a first portion of the outer housing and the electrically active surface comprises a second portion of the outer housing without the electrically insulating layer.

4. The IMD of claim 2, wherein the tissue growth-inhibiting layer extends over at least a portion of the electrically active surface.

5. The IMD of claim 1, wherein the titanium outer surface comprises a retrieval feature.

6. The IMD of claim 5, wherein the tissue growth-inhibiting layer extends over at least a portion of the retrieval feature.

7. The IMD of claim 1, wherein the tissue growth-inhibiting layer exhibits hydrolytic stability in the presence of water.

8. The IMD of claim 1, wherein the tissue growth-inhibiting layer is water-swellable.

9. A leadless cardiac pacemaker (LCP) configured for removal after having been chronically implanted, the LCP comprising:

an outer housing extending from a proximal end to a distal end;

a fixation element extending distally from the distal end;

a retrieval feature extending proximally from the proximal end;

at least a portion of the LCP including a titanium outer surface; and

a tissue growth-inhibiting layer extending over at least a portion of the titanium outer surface, the tissue growth-inhibiting layer comprising a plurality of polyethylene glycol molecules each covalently bonded to titanium atoms within the titanium outer surface.

10. The LCP of claim 9, further comprising a titanium electrode disposed relative to the outer housing.

11. The LCP of claim 9, wherein the tissue growth-inhibiting layer extends over at least a portion of the titanium electrode.

12. The LCP of claim 9, wherein the retrieval feature comprises the titanium outer surface, and the tissue growth-inhibiting layer extends over at least a portion of the retrieval feature.

13. The LCP of claim 9, wherein the outer housing comprises the titanium outer surface, and the tissue growth-inhibiting layer extends over at least a portion of the outer housing.

14. A method of instilling tissue growth resistance to at least a portion of an implantable medical device (IMD), the IMD having a titanium outer surface, the method comprising:

subjecting the titanium outer surface to a plasma treatment to provide hydroxyl groups on the titanium outer surface, the hydroxyl groups covalently bonded to titanium atoms within the titanium outer surface;

contacting the hydroxyl groups on the titanium outer surface with hydroxyl-terminated polyethylene glycol molecules; and

wherein the hydroxyl-terminated polyethylene glycol molecules covalently bond with the hydroxyl groups on the titanium outer surface with a concomitant loss of water molecules.

15. The method of claim 14, wherein contacting the hydroxyl groups on the titanium outer surface with hydroxyl-terminated polyethylene glycol molecules takes place within about one hour or less of subjecting the titanium outer surface to a plasma treatment to provide hydroxyl groups on the titanium outer surface.

16. The method of claim 14, wherein subjecting the titanium outer surface to a plasma treatment to provide hydroxyl groups on the titanium outer surface comprises a water plasma treatment.

17. The method of claim 14, wherein subjecting the titanium outer surface to a plasma treatment to provide hydroxyl groups on the titanium outer surface comprises an O₂ plasma treatment.

18. The method of claim 14, wherein the IMD is a leadless cardiac pacemaker (LCP).

19. The method of claim 14, wherein the covalently bonded polyethylene glycol molecules inhibit tissue growth.