Method and Structure for Ameliorating Side-Effects of Performing in Situ Fenestration Using a Plasma RF Catheter

• US 20090234348A1
• Filed: 03/17/2008
• Published: 09/17/2009
• Est. Priority Date: 03/17/2008
• Status: Active Grant

• Current Assignee: Medtronic Vascular, Inc. (Medtronic Plc)
• Original Assignee: Medtronic Vascular, Inc. (Medtronic Plc)
• Inventors: Bruszewski, Walter, Greenan, Trevor
• Granted Patent: US 8,197,475 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• CPC Class Codes: A61B 18/18 by applying electromagnetic radiation, e.g. microwaves radiation therapy A61N5/00

Abstract

When a main stent-graft is placed in a vessel of a patient and a branch vessel is blocked by the main stent-graft, a RF plasma catheter is used to cut out a portion of the graft cloth of the main-stent graft adjacent to an ostium of the branch vessel to be perfused. To ameliorate possible adverse effects associated with the use of the RF plasma catheter, e.g., creation of coagulum, (desiccated, coagulated blood) or perhaps a cut stent strut, a special process using saline flushing, a novel RF plasma catheter with an insulated tip, or a combination of the two is used.

Claims

1. A method comprising:

fenestrating in situ a main stent graft using a radiofrequency plasma catheter located in a branch vessel blocked by said main stent graft in a main vessel; and

reducing adverse side effects during said fenestrating in situ said main-stent graft.

2. The method of claim 1 wherein said reducing comprises:

injecting a pulse of a flush solution before, during and after said fenestrating to create an environment of essentially said flush solution about a radiofrequency electrode of said radiofrequency plasma catheter.

3. The method of claim 1 wherein said reducing comprises:

using an insulator of said radiofrequency plasma catheter to maintain a separation of said radiofrequency electrode from a strut of said main stent graft to prevent damage to said strut during said fenestrating.

4. The method of claim 2 wherein said reducing comprises:

using an insulator of said radiofrequency plasma catheter to maintain a separation of said radiofrequency electrode from a strut of said main stent graft to prevent damage to said strut during said fenestrating.

5. A method comprising:

starting a flow of a flush solution through a radiofrequency plasma catheter having an radiofrequency electrode located in a branch vessel blocked by a main stent graft located in a main vessel, wherein said main stent graft includes stent graft cloth;

creating a fenestration in said stent graft cloth by applying power to said radiofrequency electrode of said radiofrequency plasma catheter at a time t1 after the starting of said flow;

maintaining said flow of said flush solution during said applying power; and

terminating said flow of said flush solution at a time t2 after said applying power is stopped wherein said flow of said flush solution washes blood away from said radiofrequency electrode and thereby reduces coagulum formed by heating of blood associated with said applying power to said radiofrequency electrode.

6. The method of claim 5 further comprising:

using an insulator of said radiofrequency plasma catheter to maintain a separation of said radiofrequency electrode from a strut of said main stent graft during said creating.

7. The method of claim 5 wherein said flush solution comprises a saline solution.

8. The method of claim 5 wherein said flow of flush solution has a flow rate in a range from 50 ml/min to 100 ml/min.

9. The method of claim 5 wherein said flow of flush solution has a pressure in a range from 2 atmospheres to 15 atmospheres.

10. The method of claim 5 wherein said time t1 is about 50 milliseconds.

11. The method of claim 5 wherein said time t2 is about 50 milliseconds.

12. The method of claim 5 further comprising:

positioning said radio frequency electrode adjacent and in contact with said graft cloth prior to said creating.

13. A method comprising:

using an insulator of a radiofrequency plasma catheter to maintain a separation of a radiofrequency electrode of said radiofrequency plasma catheter from a strut of a main stent graft wherein said radiofrequency electrode is located in a branch vessel blocked by said main stent graft located in a main vessel, wherein said main stent graft includes stent graft cloth;

creating a fenestration in said stent graft cloth by applying power to said radiofrequency electrode of said radiofrequency plasma catheter wherein said separation prevents damage to said strut during said creating.

14. The method of claim 13 further comprising:

positioning said radio frequency electrode adjacent and in contact with said graft cloth prior to said creating.

15. A cutting radiofrequency catheter assembly comprising:

a center liner bounding a lumen;

a radiofrequency electrode coupled to said center liner at a distal end of said center liner wherein said radiofrequency electrode bounds a lumen aligned to provide a flow path from said lumen of said center liner through said radiofrequency electrode; and

a source of a pulse of a flush solution coupled to said center liner.

16. The cutting radiofrequency catheter assembly of claim 15 further comprising:

an outer insulator mounted about said radiofrequency electrode wherein a circumferential outer edge surface of said outer insulator comprises a portion of an outer circumferential edge surface of said radiofrequency catheter assembly.

17. The cutting radiofrequency catheter assembly of claim 15 further comprising:

an inner insulator mounted between said center liner and said radiofrequency electrode wherein said inner insulator bounds a lumen aligned to provide a flow path from said lumen of said center liner to said lumen of said radiofrequency electrode.

18. The cutting radiofrequency catheter assembly of claim 16 further comprising:

an inner insulator mounted between said center liner and said radiofrequency electrode wherein said inner insulator bounds a lumen aligned to provide a flow path from said lumen of said center liner to said lumen of said radiofrequency electrode.

19. The cutting radiofrequency catheter assembly of claim 15 wherein said radiofrequency electrode further comprises a convex exterior edge surface.

20. The cutting radiofrequency catheter assembly of claim 15 wherein said radiofrequency electrode further comprises a concave exterior edge surface.