Fixation methods for leadless cardiac devices

1. An implantable leadless pacing device comprising:

a power source;

circuitry operatively coupled to the power source, the circuitry configured to pace a patient's heart and/or sense electrical activity of the patient's heart;

a housing at least partially enclosing the circuitry;

a first electrode secured relative to the housing and exposed to the environment outside of the housing; and

a fixation mechanism secured relative to the housing, the fixation mechanism comprising:

one or more nitinol tines configured to move between an elongated delivery configuration and a curved deployed configuration; and

a radiopaque coating disposed on a surface of at least one tine of the one or more nitinol tines; and

wherein the radiopaque coating is a plurality of radiopaque bands positioned at intervals along a length of each tine of the one or more tines.

2. The implantable leadless pacing device of claim 1 , wherein the radiopaque coating has a thickness in the range of 5 to 100 micrometers.

3. The implantable leadless pacing device of claim 1 , wherein the radiopaque coating is deposited using physical vapor deposition.

4. The implantable leadless pacing device of claim 1 , wherein the radiopaque coating comprises gold (Au), palladium (Pd), platinum (Pt), iridium (Ir), tantalum (Ta), osmium (Os), rhenium (Re), tungsten (W), niobium (Nb), and/or alloys containing at least one radiopaque material.

5. The implantable leadless pacing device of claim 1 , wherein the radiopaque coating comprises a radiopaque loaded polymer.

6. The implantable leadless pacing device of claim 1 , further comprising an external coating disposed over the radiopaque coating.

7. The implantable leadless pacing device of claim 6 , wherein the external coating comprises parylene.

8. The implantable leadless pacing device of claim 1 , wherein a first one of the plurality of radiopaque bands is positioned at a distalmost extent of each tine of the one or more tines when the one or more tines are in the curved deployed configuration, and a second one of the plurality of radiopaque bands is positioned at a radial outwardmost extent of each tine of the one or more tines when the one or more tines are in the curved deployed configuration.

9. An implantable leadless pacing device comprising:

a power source;

circuitry operatively coupled to the power source, the circuitry configured to pace a patient's heart and/or sense electrical activity of the patient's heart;

a housing at least partially enclosing the circuitry;

a first electrode secured relative to the housing and exposed to the environment outside of the housing; and

a fixation mechanism secured relative to the housing, the fixation mechanism comprising a plurality of tines configured to move between an elongated delivery configuration and a curved deployed configuration;

wherein each tine of the plurality of tines includes a radiopaque material; and

wherein at least some of the plurality of tines include a plurality of radiopaque bands positioned at intervals along a length of each tine, the plurality of bands positioned at one or more bends of the plurality of tines when the plurality of tines are in the curved deployed configuration.

10. The implantable leadless pacing device of claim 9 , wherein at least some of the plurality of tines each comprise a nitinol tube having a lumen filled with the radiopaque material.

11. The implantable leadless pacing device of claim 10 , wherein the radiopaque material comprises gold (Au), palladium (Pd), platinum (Pt), iridium (Ir), tantalum (Ta), osmium (Os), rhenium (Re), tungsten (W), niobium (Nb), and/or alloys containing at least one radiopaque material.

12. The implantable leadless pacing device of claim 10 , wherein the radiopaque material comprises a radiopaque loaded polymer.

13. The implantable leadless pacing device of claim 9 , wherein at least some of the plurality of tines each comprise a tubular member including the radiopaque material and having a lumen filled with nitinol.

14. The implantable leadless pacing device of claim 9 , wherein at least some of the plurality of tines are formed from a layered tube.

15. The implantable leadless pacing device of claim 14 , wherein at least some of the layered tube is a rolled layered sheet.

16. The leadless pacing device of claim 14 , wherein the layered tube comprises an inner nitinol layer, an intermediate layer including the radiopaque material, and an outer nitinol layer.

17. The implantable leadless pacing device of claim 9 , wherein at least one radiopaque band of the plurality of radiopaque bands is positioned at a radial outwardmost extent of at least one of the tines when the plurality of tines are in the curved deployed configuration.

18. A fixation mechanism for securing an implantable leadless pacing device to a tissue, the fixation mechanism comprising:

a plurality of tines configured to move between an elongated delivery configuration and a curved deployed configuration;

wherein each tine of the plurality of tines includes a first material, a radiopaque material disposed on a surface of the first material, and a coating extending over at least an entirety of the radiopaque material, the coating configured to inhibit galvanic action between the first material and the radiopaque material.

19. The fixation mechanism of claim 18 , wherein the radiopaque material comprises gold (Au), palladium (Pd), platinum (Pt), iridium (Ir), tantalum (Ta), osmium (Os), rhenium (Re), tungsten (W), niobium (Nb), and/or alloys containing at least one radiopaque material.

20. The fixation mechanism of claim 18 , wherein the radiopaque material comprises a radiopaque loaded polymer.