Medical device fixation

1. An implantable medical device (IMD) comprising:

a body containing electronics;

a fixation device connected to the body of the device, wherein the fixation device comprises:

a temporary fixation mechanism comprising a biodegradable material and configured to anchor the IMD within a blood vessel of a patient after implantation until the temporary fixation mechanism biodegrades; and

a chronic fixation mechanism overlaying a first side of the body and configured to promote tissue growth along the first side of the body that anchors the IMD within the blood vessel of the patient before the temporary fixation mechanism biodegrades such that the chronic fixation mechanism is configured to more permanently anchor the IMD to the blood vessel than the temporary fixation mechanism,

wherein the temporary fixation mechanism is configured to anchor the IMD within the blood vessel such that the first side of the body including the chronic fixation mechanism is arranged against endothelium of the blood vessel, and

wherein the chronic fixation mechanism comprises a sheet of tissue growth promoting material configured to be connected to the IMD housing and configured to promote tissue growth into the material to secure the IMD within the blood vessel of the patient before the temporary fixation mechanism biodegrades, wherein the sheet of tissue growth promoting material comprises a rectangular sheet of tissue growth promoting material defined by four edges, and wherein a first edge is attached to the outer surface of the IMD housing and a second edge generally parallel to and offset from the first edge is attached to the outer surface of the IMD housing.

2. The IMD of claim 1 , wherein the temporary fixation mechanism comprises a biodegradable stent configured to be connected to at least one of a first side or a second side of the body of the IMD generally opposite the first side such that the stent is configured to push the first side of the body of the IMD including the chronic fixation mechanism against the endothelium of the blood vessel.

3. The IMD of claim 1 , wherein the blood vessel of the patient comprises at least one of the right or the left first branches of the pulmonary artery, a systemic vessel, a brain vessel, or a renal vessel.

4. The IMD of claim 1 , wherein the temporary fixation mechanism comprises at least one of polyglycolic acid (PGA), poly lactic acid (PLA), polydioxanone (PDS), polyanhydrides, trimethylene carbonate, polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), polycaprolactone, polyorthoesters, polyaminoacids, polycyanocrylates, and polyphosphazenes.

5. The IMD of claim 1 , wherein the temporary fixation mechanism comprises a biodegradable material selected from the group consisting of polyesters, polyurethanes, and combinations thereof.

6. The IMD of claim 1 , wherein the temporary fixation mechanism comprises a biodegradable material selected from the group consisting of polyglycolic acid (PGA), polylactic acid (PLA), and combinations thereof.

7. The IMD of claim 1 , wherein the temporary fixation mechanism comprises a biodegradable material selected from the group consisting of magnesium, magnesium alloys, iron, iron alloys, and combinations thereof.

8. The IMD of claim 1 , wherein the temporary fixation mechanism comprises a biodegradable material configured to substantially degrade by a first time sufficient to allow enough tissue growth to the chronic fixation mechanism to secure the IMD within the blood vessel of the patient.

9. The IMD of claim 1 , wherein the sheet of tissue growth promoting material is configured overlay at least part of an outer surface of the body.

10. The IMD of claim 1 , wherein the sheet of tissue growth promoting material comprises a sheet of flexible fabric.

11. The IMD of claim 1 , wherein the first and second edges of the rectangular sheet of tissue growth promoting material are attached to the body of the IMD such that the rectangular sheet of tissue growth promoting material is pulled taut to lay on the outer surface of the body of the IMD.

12. The IMD of claim 1 , wherein the first and second edges of the rectangular sheet of tissue growth promoting material are attached to the body of the IMD such that the rectangular sheet of tissue growth promoting material remains at least partially slack and at least a portion of the rectangular sheet of tissue growth promoting material is offset from the outer surface of the body of the IMD.

13. The IMD of claim 1 , wherein the sheet of tissue growth promoting material is selected from the group consisting of tubular-weave polyethylene velour, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) mesh, and combinations thereof.

14. The IMD of claim 1 , wherein the sheet of tissue growth promoting material comprises a sheet of metallic screen.

15. The IMD of claim 14 , wherein the sheet of metallic screen comprises at least one of titanium and stainless steel.

16. The IMD of claim 1 , wherein the electronics include a least one of a battery, a telemetry module, sensing elements and a signal generator configured to generate electrical stimulation.

17. An assembly comprising:

an implantable medical device (IMD) comprising a housing containing electronics; and

a fixation device for the IMD, the fixation device comprising:

a temporary fixation mechanism connected to the IMD, wherein the temporary fixation mechanism comprises a biodegradable material and is configured to anchor the IMD within a blood vessel of a patient after implantation until the temporary fixation mechanism biodegrades; and

a chronic fixation mechanism overlaying a first side of the IMD housing, wherein the chronic fixation mechanism is configured to promote tissue growth along the first side of the IMD housing that anchors the IMD within the blood vessel before the temporary fixation mechanism biodegrades such that the chronic fixation mechanism is configured to more permanently anchor the IMD to the blood vessel than the temporary fixation mechanism,

wherein the chronic fixation mechanism comprises a sheet of tissue growth promoting material configured to be connected to the IMD housing and configured to promote tissue growth into the material to secure the IMD within the blood vessel of the patient before the temporary fixation mechanism biodegrades, wherein the sheet of tissue growth promoting material comprises a rectangular sheet of tissue growth promoting material defined by four edges, and wherein a first edge is attached to the outer surface of the IMD housing and a second edge generally parallel to and offset from the first edge is attached to the outer surface of the IMD housing, and wherein the temporary fixation mechanism is configured to anchor the IMD within the blood vessel such that the first side of the IMD housing, including the chronic fixation mechanism, is arranged against endothelium of the blood vessel.

18. The assembly of claim 17 , wherein the temporary fixation mechanism comprises a biodegradable stent configured to be connected to at least one of the first side or a second side of the IMD housing such that the stent is configured to push the first side of the IMD housing, including the chronic fixation mechanism, against the endothelium of the blood vessel.

19. The assembly of claim 17 , wherein the blood vessel of the patient comprises at least one of the right or the left branches of the pulmonary artery, a systemic vessel, a brain vessel, or a renal vessel.

20. The assembly of claim 17 , wherein the temporary fixation mechanism comprises at least one of polyglycolic acid (PGA), polylactic acid (PLA), polydioxanone (PDS), polyanhydrides, trimethylene carbonate, polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), polycaprolactone, polyorthoesters, polyaminoacids, polycyanocrylates, and polyphosphazenes.

21. The assembly of claim 17 , wherein the temporary fixation mechanism comprises a biodegradable material selected from the group consisting of polyesters, polyurethanes, and combinations thereof.

22. The assembly of claim 17 , wherein the temporary fixation mechanism comprises a biodegradable material selected from the group consisting of polyglycolic acid (PGA), polylactic acid (PLA), and combinations thereof.

23. The assembly of claim 17 , wherein the temporary fixation mechanism comprises a biodegradable material selected from the group consisting of magnesium, magnesium alloys, iron, iron alloys, and combinations thereof.

24. The assembly of claim 17 , wherein the temporary fixation mechanism comprises a biodegradable material configured to substantially degrade by a first time sufficient to allow enough tissue growth to the chronic fixation mechanism to secure the IMD within the blood vessel of the patient.

25. The assembly of claim 17 , wherein the sheet of tissue growth promoting material is configured to at least part of an outer surface of the IMD housing.

26. The assembly of claim 17 , wherein the sheet of tissue growth promoting material comprises a sheet of flexible fabric.

27. The assembly of claim 17 , wherein the first and second edges of the rectangular sheet of tissue growth promoting material are attached to the IMD housing such that the rectangular sheet of tissue growth promoting material is pulled taut to lay on the outer surface of the IMD housing.

28. The assembly of claim 17 , wherein the first and second edges of the rectangular sheet of tissue growth promoting material are attached to the IMD housing such that the rectangular sheet of tissue growth promoting material remains at least partially slack and at least a portion of the rectangular sheet is offset from the outer surface of the IMD housing.

29. The assembly of claim 17 , wherein the sheet of tissue growth promoting material is selected from the group consisting of tubular-weave polyethylene velour, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) mesh, and combinations thereof.

30. The assembly of claim 17 , wherein the sheet of tissue growth promoting material comprises a sheet of metallic screen.

31. The assembly of claim 30 , wherein the sheet of metallic screen comprises at least one of titanium and stainless steel.

32. The assembly of claim 30 , wherein the sheet of metallic screen forms a pedestal protruding from the first side of the housing such that the housing of the IMD is offset from the endothelium of the blood vessel.

33. The assembly of claim 17 , wherein the electronics include a least one of a battery, a telemetry module, sensing elements and a signal generator configured to generate electrical stimulation.

34. A method of securing an implantable medical device (IMD) within the body of a patient, the method comprising:

arranging the IMD at a target location within a blood vessel of the patient, wherein the IMD comprises a housing containing electronics;

temporarily anchoring the IMD within the blood vessel with a temporary fixation mechanism comprising a biodegradable material, wherein the temporary fixation mechanism is configured to secure the IMD within the blood vessel after implantation until the temporary fixation mechanism biodegrades; and

chronically anchoring the IMD within the blood vessel with a chronic fixation mechanism overlaying a first side of the IMD housing and configured to promote tissue growth along the first side of the IMD housing that secures the IMD within the blood vessel before the temporary fixation mechanism biodegrades, wherein the chronic fixation mechanism is configured to more permanently anchor the IMD to the blood vessel than the temporary fixation mechanism,

wherein the temporary fixation mechanism is configured to anchor the IMD within the blood vessel such that the first side of the IMD housing including the chronic fixation mechanism is arranged against endothelium of the blood vessel, and

wherein the chronic fixation mechanism comprises a sheet of tissue growth promoting material configured to be connected to the IMD housing and configured to promote tissue growth into the material to secure the IMD within the blood vessel of the patient before the temporary fixation mechanism biodegrades, wherein the sheet of tissue growth promoting material comprises a rectangular sheet of tissue growth promoting material defined by four edges, and wherein a first edge is attached to the outer surface of the IMD housing and a second edge generally parallel to and offset from the first edge is attached to the outer surface of the IMD housing.

35. The method of claim 34 , wherein the electronics include a least one of a battery, a telemetry module, sensing elements and a signal generator configured to generate electrical stimulation.