IN-VIVO CALIBRATION OF CONTACT FORCE-SENSING CATHETERS USING AUTO ZERO ZONES

• US 20130085416A1
• Filed: 09/30/2011
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Original Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Inventors: Mest, Robert Alan
• Granted Patent: US 10,791,950 B2
• Time in Patent Office: Days
• US Class Current: 600/587
• 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 2017/00725 Calibration or performance testing
• CPC Class Codes: A61B 2018/00357 Endocardium
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency

Abstract

A method for the in vivo re-calibration of a force sensing probe such as an electrophysiology catheter provides for the generation of an auto zero zone. The distal tip of the catheter or other probe is placed in a body cavity within the patient. Verification that there is no tissue contact is made using electrocardiogram (ECG) or impedance data, fluoroscopy or other real-time imaging data and/or an electro-anatomical mapping system. Once verification that there is no tissue contact is made, the system recalibrates the signal emanating from the force sensor setting it to correspond to a force reading of zero grams and this recalibrated baseline reading is used to generate and display force readings based on force sensor data.

Claims

1. A method for calibrating a probe having a force sensor near the distal end of the probe comprising the steps of:

inserting the probe into a body cavity of a patient;

receiving at a signal processor a first signal from the force sensor indicative of the force being applied to the distal end of the probe;

verifying that the distal tip of the probe is not in contact with tissue of the patient;

calibrating the processor to set the first signal from the force sensor to a force reading of zero.

2. The method of claim 1 further comprising the steps of:

receiving location information at the signal processor indicative of the location of the distal tip of the probe in three-dimensional space;

storing the location of the distal tip of the probe as a location of an auto zero zone.

3. The method of claim 2 further comprising the steps of:

manipulating the probe to a stored auto zero zone location;

receiving at the signal processor a second signal from the force sensor indicative of the force being applied to the distal end of the probe;

recalibrating the processor to set the second signal from the force sensor to a force reading of zero.

4. The method of claim 2 further comprising the steps of:

continuously monitoring the location of the distal tip of the probe;

receiving at the signal processor a second signal from the force sensor indicative of the force being applied to the distal end of the probe;

recalibrating the processor to set the second signal from the force sensor to a force reading of zero when the location of the distal tip of the probe is equivalent to an auto zero zone location.

5. The method of claim 1 wherein the step of verifying comprises using a least one of electrocardiogram data, electrode impedance data, fluoroscopic imaging, real-time MRI, real-time CT or electro-anatomic mapping system images or data to determine of the distal tip of the probe is in contact with tissue.

6. The method of claim 2 wherein the step of receiving location information regarding the distal tip of the catheter comprises receiving the spatial coordinates and pitch, roll and yaw of the location sensor.

7. The method of claim 1 wherein the probe comprises a cardiac catheter.

8. The method of claim 1 wherein the body cavity comprises a chamber of a heart.

9. The method of claim 7 wherein the cardiac catheter is an ablation catheter having an electrode at the tip and wherein the tip electrode can also be used to record ECG data and/or impedance data.

10. The method of claim 2 wherein the auto zero zone is expanded from a single point using reconstructed tissue geometry from an electro-anatomic mapping system to determine a three-dimensional auto zero zone around the single auto zero zone location that has been verified and located.

11. A system for re-calibrating force sensing probes comprising;

a probe capable of being inserted into the body cavity of a patient and comprising a force sensor that provide a plurality of signals over time indicative of the force applied to the probe as the force varies over time;

a means for determining if the probe is in contact with tissue in the body cavity of the patient;

a processor configured to receive the plurality of signals indicative of the force and generating a force reading indicative of the force on the probe wherein the processor sets the force reading to zero when the means for determining if the probe is in contact determine that there is no contact between the probe and the body cavity of the patient.

14. The system of claim 11 wherein the probe is an electrophysiology catheter.

15. The system of claim 14 wherein the electrophysiology catheter has at least one electrode mounted on the distal end of the catheter.

16. The system of claim 15 wherein the means for determining contact between the catheter and the tissue of the patient is based on electrocardiogram and/or impedance signals from at least one of the electrodes.

17. The system of claim 11 wherein the means for determining contact between the probe and the tissue of the patient is a fluoroscopic image.

18. The system of claim 11 wherein the means for determining contact between the probe and the tissue of the patient is a real-time CT image.

19. The system of claim 11 wherein the means for determining contact between the probe and the tissue of the patient is a real-time magnetic resonance image (MRI).

20. The system of claim 11 wherein the means for determining contact between the probe and the tissue of the patient is data and/or images from an electroanatomic mapping system.

24. The system of claim 20 where the distance between the probe and the tissue of the patient based on data from the electro-anatomic mapping system is used to determine if there is tissue contact.

25. The system of claim 24 wherein the system automatically assumes there is no tissue contact if the distance d exceeds a pre-determined threshold.

26. The method of claim 20 wherein the auto zero zone is expanded from a single point using reconstructed tissue geometry from an electro-anatomic mapping system to determine a three-dimensional auto zero zone around the single auto zero zone location that has been verified and located.

12. The system of claim 12 wherein the system further comprises a location sensor capable of providing the processor with a plurality of electrical signals indicative of the location of the probe within three dimensional space and wherein the location of the probe is stored in memory as an auto zero zone when there is no contact between the probe and the body cavity of the patient at the given location.

13. The system of claim 12 wherein the processor monitors the location of the probe and resets the force reading to zero when the probe is at a location stored in memory as an auto zero zone.

21. The system of claim 13 wherein the automatic zeroing zone locations are stored with information regarding the point in the cardiac cycle at which the location information was taken.

22. The system of claim 13 wherein the automatic zeroing zone locations are stored with information regarding the point in respiratory cycle at which the location information was taken.

23. The system of claim 12 wherein the location sensor is a magnetic location sensor capable of providing the processor with three-dimensional location coordinates and three degrees of orientation (pitch, roll and yaw) of the probe.