Impedance-Based Cardiac Therapy Planning Method with a Remote Surgical Navigation System

• US 20080065061A1
• Filed: 09/10/2007
• Published: 03/13/2008
• Est. Priority Date: 09/08/2006
• Status: Active Grant

• Current Assignee: Stereotaxis, Inc.
• Original Assignee: Stereotaxis, Inc.
• Inventors: Viswanathan, Raju R.
• Granted Patent: US 8,273,081 B2
• Time in Patent Office: Days
• US Class Current: 606/41
• 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 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/376 using X-rays, e.g. fluoroscopy
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• 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 5/0536 Impedance imaging, e.g. by tomography
• CPC Class Codes: A61B 5/283 Invasive

Abstract

A method is disclosed for planning the treatment of cardiac arrhythmias by RF ablation with a remote navigation system, including the identification of ablation lines around the pulmonary veins ostia—atrial junctions based on impedance measurements. When used by itself or in conjunction with electro-anatomical approaches, the impedance method therein disclosed enables safe and effective arrhythmia treatment.

Claims

1. A method of performing intra-cardiac ablation with a remote navigation system, comprising:

i) collecting electrical activity information at a plurality of points within a chamber of the heart and adjoining vessels;

ii) measuring impedance at a plurality of points within the heart chamber and adjoining vessels of step i);

iii) developing a three-dimensional map of the heart based on the impedance and electrical activity measurements of steps ii) and i);

iv) automatically defining a set of ablation lines based on the three-dimensional map of step iii);

v) guiding an ablation catheter using the remote navigation system to the heart chamber of step i); and

vi) performing ablation along the set of ablation lines of step iv).

2. The method of claim 1, further comprising using imaging to guide the three dimensional mapping.

3. The method of claim 1, further comprising using imaging to guide the ablation catheter.

4. The method of claim 1, wherein electrical and impedance measurements are performed within the left atrium and within the pulmonary veins near the ostia.

5. The method of claim 1, wherein the heart chamber is the left atrium and the adjoining vessels are the pulmonary veins.

6. The method of claim 1, wherein the ablation lines definition of step iv) relies at least in part on the use of iso-impedance contours.

7. The method of claim 1, wherein the remote navigation system comprises at least one of the activation mechanisms selected from the group consisting of (1) a magnetic navigation system;

(2) a mechanical navigation system; and

(3) an electrostrictive navigation system.

8. A method of defining ablation lines in the left atrium of the heart, comprising:

i) performing impedance mapping of the left atrium and a pair of pulmonary veins;

ii) for each pulmonary vein, defining an impedance threshold value corresponding to the pulmonary vein ostium;

iii) defining iso-impedance contours for each of the veins based on corresponding impedance threshold ii) and impedance mapping i);

iv) determining whether the two iso-impedance contours iii) are

a) crossing;

b) tangent;

or c) neither;

v) increasing or decreasing the two respective impedance contour values by a predetermined amount if the contours are crossing, or not, respectively, and defining corresponding iso-impedance contours;

vi) iterating over steps iv) and v) until the two contours are tangent, and defining an associated single iso-impedance contour; and

vii) retaining the corresponding iso-impedance contour as a pulmonary vein pair ablation line.

9. The method of claim 8, further comprising decreasing the contour impedance of the single contour of step vi) by a second predetermined amount and retaining the corresponding iso-impedance contour as a pulmonary vein pair ablation line.

10. The method of claim 8, further comprising using imaging to guide the selection of the ablation lines.

11. The method of claim 8, further comprising performing a plurality of electrical activity measurements within the left atrium to guide the selection of the ablation lines.

12. A method of performing intra-cardiac ablation using a remote navigation system, comprising:

i) measuring impedance at a plurality of points within a heart chamber and adjoining vessels;

ii) developing a three-dimensional map of the heart based on the impedance measurements of step i);

iii) automatically defining a set of ablation lines based on the three-dimensional map of step ii);

iv) using the remote navigation system to guide an ablation catheter to the heart chamber of step i) using impedance data; and

v) performing ablation along the set of ablation lines of step iii).

13. The method of claim 12, wherein the ablation lines definition of step iii) relies at least in part on the use of iso-impedance contours.

14. The method of claim 12, further comprising using imaging to guide the three dimensional mapping.

15. The method of claim 12, further comprising using imaging to guide the ablation catheter.

16. The method of claim 12, wherein impedance measurements are performed within the left atrium and within the pulmonary veins near the ostia.

17. The method of claim 12, further comprising measuring electrical activity at a plurality of points within the heart chamber and adjoining vessels.

18. The method of claim 12, further comprising using electrical activity measurements to guide the ablation catheter.

19. The method of claim 12, wherein electrical activity measurements are performed within the left atrium and within the pulmonary veins near the ostia.

20. The method of claim 12, wherein the remote navigation system comprises at least one of the activation mechanisms selected from the group consisting of (1) a magnetic navigation system;

(2) a mechanical navigation system; and

(3) an electrostrictive navigation system.

21. A computer-based method of defining ablation lines joining a set of at least two previously defined ablation lines, the method comprising:

i) selecting a seed point within an area encompassing the set of known ablation lines, and retaining said point impedance value as an iso-impedance contour impedance value;

ii) automatically defining an iso-impedance contour associated with the contour impedance value; and

iii) iteratively increasing or decreasing the iso-impedance contour impedance value, until the corresponding iso-impedance contour intersects all of the lines in the set of known ablation lines.

22. The method of claim 21, further comprising increasing or decreasing the final iso-impedance contour impedance value of step iii) to define a set of joining impedance lines.

23. A computer-based method of planning the ablation therapy of the left atrium of the heart using a remote navigation system, comprising:

i) automatically defining two ablation contours, the first around the left pair of pulmonary veins, the second around the right pair of pulmonary veins, the defining comprising using impedance information;

ii) automatically defining ablation lines joining the left and right pulmonary vein pairs, the defining comprising defining a seed point and using impedance information; and

iii) determining the final set of ablation lines as comprising the two pulmonary vein ablation contours of step i) and the joining ablation lines of step ii).

24. A method of performing tissue ablation with a remote navigation system, comprising:

i) measuring impedance values at a plurality of tissue locations in the neighborhood of the planned ablation;

ii) developing a 3D impedance model based on measurements in i);

iii) selecting impedance values appropriate for tissue ablation; and

iv) automatically defining so-impedance contours from the impedance values selected in iii) as ablation lines.

25. The method of claim 24, wherein step iii) of selecting impedance values appropriate values for tissue ablation relies on electro-anatomical information measured in the neighborhood of the planned ablation.

26. The method of claim 24, wherein the remote navigation system comprises at least one of the activation mechanisms selected from the group consisting of (1) a magnetic navigation system;

(2) a mechanical navigation system; and

(3) an electrostrictive navigation system.