DETERMINING THE POSITION OF AN ELECTRODE RELATIVE TO AN INSULATIVE COVER

• US 20090264751A1
• Filed: 04/15/2009
• Published: 10/22/2009
• Est. Priority Date: 04/18/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc), Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Receveur, Rogier, Phillips, Lane A., Markowitz, H. Toby, Falkner, Phillip, Warman, Eduardo N., Karamanoglu, Mustafa, Waldhauser, Steven L., Zhang, Shangqian Peter, Larik, Vincent, Michels, Koen, Giese, Chad, Eick, Olaf, Craig, Brian Houston, Scanlon, David A., Interrante, Victoria, Kryger, Michael, Campbell-Massa, Sean, Smith, Marie P., Fleming, Ioana, Hurtig, Noelle Christine, Chelgren, Brent, Mehta, Pooja, Nowak, Karl Evan, Steeves, James
• Granted Patent: US 8,391,965 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• CPC Class Codes: A61B 2017/00022 Sensing or detecting at the treatment site
• CPC Class Codes: A61B 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00053 Mapping
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/00243 cardiac
• CPC Class Codes: A61B 2017/22051 with an inflatable part, e.g. balloon, for positioning, blocking, or immobilisation A61B2017/22048, A61B2017/3486 take precedence
• CPC Class Codes: A61B 2034/102 Modelling of surgical devices, implants or prosthesis
• CPC Class Codes: A61B 2034/105 Modelling of the patient, e.g. for ligaments or bones
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2034/2068 using pointers, e.g. pointers having reference marks for determining coordinates of body points
• CPC Class Codes: A61B 2034/2072 Reference field transducer attached to an instrument or patient
• CPC Class Codes: A61B 2090/061 for measuring dimensions, e.g. length
• CPC Class Codes: A61B 2090/063 for measuring volume
• CPC Class Codes: A61B 2090/371 with simultaneous use of two cameras
• CPC Class Codes: A61B 2090/376 using X-rays, e.g. fluoroscopy
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 34/25 User interfaces for surgical systems
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 : invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/063 : using impedance measurements
• CPC Class Codes: A61B 5/066 : Superposing sensor position on an image of the patient, e.g. obtained by ultrasound or x-ray imaging
• CPC Class Codes: A61B 5/068 : using impedance sensors
• CPC Class Codes: A61B 5/287 : Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 8/06 : Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: G06T 19/003 : Navigation within 3D models or images

Abstract

A volume of a patient can be mapped with a system operable to identify a plurality of locations and save a plurality of locations of a mapping instrument. The mapping instrument can include one or more electrodes that can sense a voltage that can be correlated to a three dimensional location of the electrode at the time of the sensing or measurement. Therefore, a map of a volume can be determined based upon the sensing of the plurality of points without the use of other imaging devices. An implantable medical device can then be navigated relative to the mapping data.

Claims

1. A method of determining that an instrument is exposed to a conductive medium, comprising:

positioning the instrument within a volume;

determining a first position of a first position element and a second position element both connected to the instrument;

determining a second position of the first position element and the second position element connected to the instrument;

comparing the determined first position and the determined second position; and

determining whether map data collected with the instrument is valid on the basis of whether at least one of the first position element and the second position element is insulated from the conductive medium in the volume by an insulator of the instrument.

2. The method of claim 1, providing an output to a user identifying that at least one of the first position element and the second position element is insulated.

3. The method of claim 2, wherein the output includes displaying an icon on a display device relative to a map of the volume in a sheathed color.

4. The method of claim 1, wherein comparing the determined first position and the determined second position includes comparing a distance traveled by at least one of the first position element and the second position element between two successive time steps;

wherein determining whether at least one of the first position element and the second position element is insulated includes determining that at least one of the first position element and the second position element traveled a distance past a significance threshold between two successive time steps.

5. The method of claim 3, wherein the significance threshold is a determination that a current observed distance traveled is at least 4.5 times that of an immediately previous distance traveled raised to the fourth power.

6. The method of claim 1, wherein comparing the determined first position and the determined second position includes determining a first direction traveled of the first position element and a second direction traveled of the second position element.

7. The method of claim 6, wherein determining whether at least one of the first position element and the second position element is insulated includes determining that the first direction of the first position element and the second direction of the second position element are different to a direction threshold value greater than a dot product of the vectors of the first position element and the second position element.

8. The method of claim 6, wherein the dot product threshold is about 0.25.

9. The method of claim 1, wherein comparing the determined first position and the determined second position includes determining includes comparing a distance traveled of the first position element and the second position element in a single timestep.

10. The method of claim 9, wherein determining whether at least one of the first position element and the second position element is insulated includes determining that the compared distance traveled of the first position element and the second position element is significantly different.

11. The method of claim 10, wherein the significantly different distance is at least three times.

12. The method of claim 1, wherein comparing the determined first position and the determined second position includes determining whether a distance between the first position element and the second position element on the instrument has changed.

13. The method of claim 12, wherein determining whether at least one of the first position element and the second position element is insulated includes determining that the distance between the first position element and the second position element has changed by a significant spacing amount.

14. The method of claim 13, wherein the significant spacing amount is five times a previous distance between the first position element and the second position element.

15. The method of claim 1, further comprising:

generating a map of the volume based on the first determined positions and the second determined positions;

wherein the generated map is based on determined positions only when the first position element and the second position element are not within the insulator.

16. A method of determining that an instrument is exposed to a conductive medium, comprising:

positioning the instrument within a volume;

determining a maximum distance the instrument can travel in the volume;

determining the position of the instrument at a selected timestep;

determining whether the determined position of the instrument is past the maximum distance; and

marking the instrument as sheathed if it is determined that the instrument has traveled further than the maximum distance.

17. The method of claim 16, wherein marking the instrument as sheathed includes displaying an icon on a display device in a sheathed color.

18. The method of claim 16, further comprising:

determining the time interval required for the instrument to travel a distance greater than the maximum distance.

19. The method of claim 16, further comprising:

generating a map of the volume based on a determined plurality of positions of the instrument;

wherein the generated map is based on positions determined only when the instrument is not marked as sheathed.