SYSTEM AND METHOD FOR MEASURING FORCE AND TORQUE APPLIED TO A CATHETER ELECTRODE TIP

• US 20100168620A1
• Filed: 12/31/2008
• Published: 07/01/2010
• Est. Priority Date: 12/31/2008
• Status: Active Grant

• Current Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Original Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Inventors: Sliwa, John W., Klimovitch, Gleb V.
• Granted Patent: US 8,864,757 B2
• Time in Patent Office: Days
• US Class Current: 600/587
• CPC Class Codes: A61B 18/02 by cooling, e.g. cryogenic techniques devices for cooling specific reflex points of the body within cell-life limits A61H39/06
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 18/24 with a catheter A61B18/26, A61B18/28 take precedence
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 2218/002 Irrigation
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 7/022 intracavitary

Abstract

A contact sensing assembly including a catheter including an electrode having a base portion mounted adjacent a head portion of the catheter body. A sensor is disposed adjacent the base portion for measuring compression or tensile forces applied to an electrode tip portion, and includes a predetermined sensitivity. The base and head portions include predetermined rigidity so that forces applied to the electrode tip portion are determinable as a function of the sensitivity and a sensor output. A contact sensing assembly also includes an electrode pipe operatively connected to the catheter body for movement and bending with the catheter body, and an electrode wire disposed in the electrode pipe and including isolation. A change in capacitance resulting from movement of the electrode wire toward the electrode pipe or contact of the electrode wire with the electrode pipe during bending of the catheter correlates to a force applied to the catheter.

Claims

1. A contact sensing assembly comprising:

a catheter including a body having a proximal end and a distal end;

an electrode including a tip portion and a base portion mounted adjacent a head portion of the catheter body; and

at least one force and torque sensor disposed generally adjacent the base portion and including at least one pressure sensor for measuring pressure applied to the electrode tip portion and providing a pressure signal related to the measured pressure, the pressure sensor including a predetermined sensitivity,

wherein the base and head portions include a predetermined rigidity so that force applied to the electrode tip portion is determinable as a function of the predetermined sensitivity and the pressure signal.

2. The assembly according to claim 1, further comprising a plurality of pressure sensors, wherein the individual pressure sensor output signals allow a vector reconstruction of a net tip contact force using a vector addition algorithm or relationship.

3. The assembly according to claim 1, further comprising a plurality of pressure sensors, wherein the force applied to the electrode tip portion is determinable as a sum of a voltage output signal of each pressure sensor respectively divided by the predetermined sensitivity of each pressure sensor.

4. The assembly according to claim 1, further comprising a plurality of pressure sensors, wherein torque applied to the electrode tip portion is determinable as a function of a voltage output signal of each pressure sensor respectively divided by the predetermined sensitivity of each pressure sensor, and a distance of the pressure sensors from a central axis of the electrode.

5. The assembly according to claim 1, further comprising three symmetrically disposed pressure sensors, wherein for an electrode having a central axis disposed along a z-direction, torque applied to the electrode tip portion is determinable as follows:

T_y=3/4*D*(V_c/α

_c−

V_a/α

_a−

V_b/α

_b), where T_y is the torque applied to the electrode tip portion in a y-direction, D is a diameter of a circle passing through the centers of each pressure sensor, V is a voltage output of each respective pressure sensor, and α

is the predetermined sensitivity of each respective pressure sensor.

6. The assembly according to claim 1, further comprising three symmetrically disposed pressure sensors, wherein for an electrode having a central axis disposed along a z-direction, torque applied to the electrode tip portion is determinable as follows:

T_x=sqrt(3)/2*D*(V_a/α

_a−

V_b/α

_b), where T_x is the torque applied to the electrode tip portion in a x-direction, D is a diameter of a circle passing through the centers of each pressure sensor, V is a voltage output of each respective pressure sensor, and α

is the predetermined sensitivity of each respective pressure sensor.

7. The assembly according to claim 1, wherein the generally distal end of the catheter includes a coupling member connecting the electrode to the catheter body.

8. The assembly according to claim 7, wherein the coupling member comprises an elastic material.

9. The assembly according to claim 1, wherein the pressure sensors are emplaced in an interface between at least two annular or circular rings.

10. The assembly according to claim 1, wherein the tip portion of the electrode includes an irrigation port.

11. The assembly according to claim 1, wherein the electrode comprises one of an RF ablation electrode, a HIFU ablation transducer, a laser ablation assembly, a cryogenic ablation assembly, an ultrasonic imaging apparatus, an electrical cardiac pacing electrode, and an electrical cardiac sensing electrode.

12. The assembly according to claim 2, wherein the plurality of pressure sensors are fabricated using at least one of flex circuit technology, lithographic technology, thin-film technology, and thick film technology.

13. The assembly according to claim 1, further comprising a proximal control handle including at least one catheter deflection or articulation control, and at least one switch for controlling a diagnostic or therapeutic function of the electrode.

14. The assembly according to claim 1, wherein the force applied to the electrode tip is utilized for at least one of:

a) automatically limiting a maximum force;

b) warning of a high or unacceptable force;

c) giving visual or audible feedback to a practitioner regarding a tissue contact force;

d) warning of a loss of contact force or contact; and

e) warning of a contact force which is too low.

15. A contact sensing assembly comprising:

a catheter including a body having a proximal end and a distal end;

an electrode including a tip portion and a base portion mounted adjacent a head portion of the catheter body; and

at least one sensor disposed generally adjacent the base portion for measuring compression or tensile forces applied to the electrode tip portion and providing an output signal related to the measured forces, the sensor including a predetermined sensitivity,

wherein the base and head portions include a predetermined rigidity so that the compression or tensile forces applied to the electrode tip portion are determinable as a function of the predetermined sensitivity and the output signal.

16. The assembly according to claim 15, further comprising a plurality of sensors, wherein the individual sensors each generate an output signal that together provide a vector reconstruction of a net tip contact force using a vector addition algorithm or relationship.

17. The assembly according to claim 15, further comprising a plurality of sensors, wherein the compression or tensile force applied to the electrode tip portion is determinable as a sum of the output signals of each sensor respectively divided by the predetermined sensitivity of each sensor.

18. The assembly according to claim 15, further comprising a plurality of sensors, wherein torque applied to the electrode tip portion is determinable as a function of the output signal of each sensor respectively divided by the predetermined sensitivity of each sensor, and a distance of the sensors from a central axis of the electrode.

19. The assembly according to claim 15, further comprising three symmetrically disposed sensors, wherein for an electrode having a central axis disposed along a z-direction, torque applied to the electrode tip portion is determinable as follows:

T_y=¾

*D*(V_c/α

_c−

V_a/α

_a−

V_/α

_b), where T_y is the torque applied to the electrode tip portion n a y-direction, D is a diameter of a circle passing through the centers of each sensor, V is a voltage output of each respective sensor, and α

is the predetermined sensitivity of each respective sensor.

20. The assembly according to claim 15, further comprising three symmetrically disposed sensors, wherein for an electrode having a central axis disposed along a z-direction, torque applied to the electrode tip portion is determinable as follows:

T_x=sqrt(3)/2*D*(V_a/α

_a−

V_b/α

_b), where T_x is the torque applied to the electrode tip portion in a x-direction, D is a diameter of a circle passing through the centers of each sensor, V is a voltage output of each respective sensor, and α

is the predetermined sensitivity of each respective sensor.

21. The assembly according to claim 15, wherein the generally distal end of the catheter includes a coupling member connecting the electrode to the catheter body.

22. The assembly according to claim 21, wherein the coupling member comprises an elastic material.

23. The assembly according to claim 15, wherein the sensors are emplaced in an interface between at least two annular or circular rings.

24. The assembly according to claim 15, wherein the tip portion of the electrode includes an irrigation port.

25. The assembly according to claim 15, wherein the electrode comprises one of an RF ablation electrode, a HIFU ablation transducer, a laser ablation apparatus, a cryogenic ablation assembly, an ultrasonic imaging transducer, a cardiac pacing electrode, and a cardiac sensing electrode.

26. The assembly according to claim 15, wherein the sensors are fabricated using at least one of flex circuit technology, lithographic technology, thin-film technology, and thick film technology.

27. The assembly according to claim 15, further comprising a proximal control handle including at least one catheter deflection or articulation control, and at least one switch for controlling a diagnostic or therapeutic function of the electrode.

28. The assembly according to claim 15, wherein the compression or tensile force applied to the electrode tip is utilized for at least one of:

a) automatically limiting a maximum force;

b) warning of a high or unacceptable force;

c) giving visual or audible feedback to a practitioner regarding a tissue contact force;

d) warning of a loss of contact force or contact; and

e) warning of a contact force which is too low.

29. The assembly according to claim 15, wherein the sensor is one of a resistive force sensor, a capacitive force sensor, and an optical force sensor.

30. A contact sensing assembly comprising:

a catheter including a body having a proximal end and a distal end;

an electrode pipe disposed in the catheter body; and

an electrode wire disposed in the electrode pipe and including isolation thereon,

wherein a change in capacitance resulting from movement of the electrode wire toward the electrode pipe or contact of the electrode wire with the electrode pipe during bending of the catheter directly correlates to a force applied to the catheter.

31. The assembly according to claim 30, wherein the electrode wire and electrode pipe are mechanically coupled toward a distal end thereof.

32. The assembly according to claim 30, wherein an electrode operatively connected to the catheter comprises one of an RF ablation electrode, a HIFU ablation transducer, a laser ablation apparatus, a cryogenic ablation assembly, an ultrasonic imaging transducer, a cardiac pacing electrode, and a cardiac sensing electrode.

33. The assembly according to claim 30, further comprising a proximal control handle including at least one catheter deflection or articulation control, and at least one switch for controlling a diagnostic or therapeutic function of an electrode operatively connected to the catheter.

34. The assembly according to claim 30, wherein the force applied to the catheter is utilized for at least one of:

a) automatically limiting a maximum force;

b) warning of a high or unacceptable force;

c) giving visual or audible feedback to a practitioner regarding a tissue contact force;

d) warning of a loss of contact force or contact; and

e) warning of a contact force which is too low.

35. A contact sensing assembly comprising:

a catheter including a body having a proximal end and a distal end;

an electrode pipe operatively connected to the catheter body for at least one of movement and bending with the catheter body; and

an electrode wire disposed in the electrode pipe and including isolation thereon,

wherein a change in capacitance resulting from movement of the electrode wire toward the electrode pipe or contact of the electrode wire with the electrode pipe during bending of the catheter directly correlates to a force applied to the catheter.

36. The assembly according to claim 35, wherein the electrode wire and electrode pipe are mechanically coupled toward a distal end thereof.

37. The assembly according to claim 35, wherein an electrode operatively connected to the catheter comprises one of an RF ablation electrode, a HIFU ablation transducer, a laser ablation apparatus, a cryogenic ablation assembly, an ultrasonic imaging transducer, a cardiac pacing electrode, and a cardiac sensing electrode.

38. The assembly according to claim 35, further comprising a proximal control handle including at least one catheter deflection or articulation control, and at least one switch for controlling a diagnostic or therapeutic function of an electrode operatively connected to the catheter.

39. The assembly according to claim 35, wherein the force applied to the catheter is utilized for at least one of:

a) automatically limiting a maximum force;

b) warning of a high or unacceptable force;

c) giving visual or audible feedback to a practitioner regarding a tissue contact force;

d) warning of a loss of contact force or contact; and

e) warning of a contact force which is too low.