METHODS OF USING HIGH INTENSITY FOCUSED ULTRASOUND TO FORM AN ABLATED TISSUE AREA CONTAINING A PLURALITY OF LESIONS

• US 20100217162A1
• Filed: 05/03/2010
• Published: 08/26/2010
• Est. Priority Date: 05/25/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Lee, Hotaik, Smith, Nadine B., Keough, James R., Francischelli, David E., Hissong, James B., Stewart, Mark T., Skarda, James R.
• Granted Patent: US 9,227,088 B2
• Time in Patent Office: Days
• US Class Current: 601/3
• CPC Class Codes: A61B 2017/320069 for ablating tissue
• CPC Class Codes: A61B 2017/32007 with suction or vacuum means
• CPC Class Codes: A61B 2017/320071 with articulating means for working tip
• CPC Class Codes: A61B 2017/320078 Tissue manipulating surface
• CPC Class Codes: A61B 2018/00291 using suction
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/378 using ultrasound
• CPC Class Codes: A61B 2090/3782 transmitter or receiver in catheter or minimal invasive instrument
• 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 8/4281 characterised by sound-transmitting media or devices for coupling the transducer to the tissue
• CPC Class Codes: A61N 2007/0078 with multiple treatment transducers
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: A61N 7/022 intracavitary

Abstract

A device and method for ablating tissue is disclosed comprising the steps of acquiring an anatomical image of a patient, correlating the image to the patient, guiding an ablating member within the patient while tracking the position of the ablating member in the patient, positioning the ablating member in a desired position to ablate tissue, emitting ablating energy from the ablating member to form an ablated tissue area and removing the ablating member from the patient.

Claims

1. A trans-esophageal ablation device for ablating tissue within a patient, comprising:

a flexible, elongate portion adapted to be guided within said patient;

a source of energy;

a two-dimensional array of transducer elements operatively coupled to said elongate portion and said source of energy, said array of transducer elements configured to deliver high intensity focused ultrasound (HIFU) energy to a focus zone within said patient and which may also deliver HIFU energy to a grating lobe;

wherein each of said transducer elements are selectively actuatable to allow for electronic steering of said HIFU energy; and

wherein said transducer elements have a taper wherein said transducer elements positioned more centrally in said array are larger than said transducer elements positioned more peripherally in said array.

2. The trans-esophageal ablation device of claim 1 wherein said taper comprises a gradual and consistent reduction in size of said transducer elements from a center of said array to a periphery of said array.

3. The trans-esophageal ablation device of claim 1 wherein said taper is configured such that high intensity focused ultrasound energy delivered from said array is at least approximately three decibels greater intensity at said focus zone in comparison with said grating lobe.

4. The trans-esophageal ablation device of claim 1 wherein each of said transducer elements has an approximately equal impedance to each other ones of said transducer elements.

5. The trans-esophageal ablation device of claim 4 further comprising an impedance match circuit operatively coupled to said transducer elements and providing, at least in part, said approximately equal impedance of each of said transducer elements to each other ones of said transducer elements.

6. The trans-esophageal ablation device of claim 5 wherein said impedance is approximately fifty ohms at a temperature of zero degrees centigrade.

7. The trans-esophageal ablation device of claim 4, further comprising:

an acoustic membrane having an acoustic impedance and positioned with respect to said trans-esophageal transducer array; and

a fluid contained within said ablation device, at least in part, by said acoustic membrane, said fluid having a fluid impedance;

wherein said acoustic impedance of the membrane is approximately equal to said acoustic impedance of said fluid.

8. The trans-esophageal ablation device of claim 7 wherein the acoustic membrane is comprised of a material having a thickness, said thickness of said membrane being a function of a difference between a speed of sound through said material and a speed of sound through said fluid to reduce a refraction of said HIFU energy through said material.

9. The trans-esophageal ablation device of claim 1:

wherein said array further comprises a number of grid elements and wherein said array has a number of said transducer elements;

wherein said transducer elements of said array are spatially sparse due to said number of grid elements being greater than said number of transducer elements.

10. The trans-esophageal ablation device of claim 1 wherein said two-dimensional array of transducer elements is a two-dimensional phased array of transducer elements.

11. A two-dimensional transducer array for trans-esophageal ablation of tissue within a patient, comprising:

a plurality of transducer elements positioned in an array having a face, said plurality of transducer elements being configured to deliver high intensity focused ultrasound (HIFU) energy to a focus zone a predetermined distance from said face and which may also deliver HIFU energy to a grating lobe;

wherein each of said plurality of transducer elements are selectively actuatable to allow for electronic steering of said HIFU energy; and

wherein said plurality of transducer elements have a taper wherein individual ones of said plurality of transducer elements positioned more centrally in said array are larger than individual ones of said plurality of transducer elements positioned more peripherally in said array.

12. The transducer array of claim 11 wherein said taper comprises a gradual and consistent reduction in size of said plurality of transducer elements from a center of said array to a periphery of said array.

13. The transducer array of claim 11 wherein said taper is configured such that high intensity focused ultrasound energy delivered from said array is at least approximately three decibels greater intensity at said focus zone in comparison with said grating lobe.

14. The transducer array of claim 11 wherein each of said plurality of transducer elements has an approximately equal impedance to each other ones of said plurality of transducer elements.

15. The transducer array of claim 14 further comprising an impedance match circuit operatively coupled to said plurality of transducer elements and providing, at least in part, said approximately equal impedance of each of said plurality of transducer elements to each other ones of said plurality of transducer elements.

16. The transducer array of claim 15 wherein said impedance is approximately fifty ohms at a temperature of zero degrees centigrade.

17. The transducer array of claim 11:

wherein said array further comprises a number of grid elements and wherein said array has a number of said plurality of transducer elements;

wherein said plurality of transducer elements of said array are spatially sparse due to said number of grid elements being greater than said number of transducer elements.

18. The transducer array of claim 11 wherein said transducer array is a two-dimensional phased array of transducer elements.

19. A method for trans-esophageal ablation of cardiac tissue in a patient with a trans-esophageal ablation device comprising a flexible, elongate portion adapted to be guided within an esophagus of said patient, a source of energy, and a two-dimensional array of transducer elements configured to deliver high intensity focused ultrasound (HIFU) energy to a focus zone within said patient, comprising said steps of:

inserting said trans-esophageal ablation device into an esophagus of said patient;

positioning said transducer array of said trans-esophageal ablation device proximate said cardiac tissue of said patient;

focusing said focus zone of said transducer array on said cardiac tissue of said patient;

delivering high intensity focused ultrasound energy to said cardiac tissue of said patient to form a lesion at said cardiac tissue without forming a lesion in patient tissue not within said focus zone.

20. The method of claim 19 wherein said HIFU energy delivered from said array is at least approximately three decibels greater intensity at said focus zone in comparison with a grating lobe.

21. The method of claim 19 wherein said trans-esophageal ablation device further comprises an impedance match circuit operatively coupled to the transducer elements, and wherein said focusing step comprises providing, at least in part, an approximately equal impedance of each of said transducer elements to each other ones of said transducer elements using said impedance match circuit.

22. The method of claim 21 wherein said impedance is approximately fifty ohms at a temperature of zero degrees centigrade.

23. The method of claim 19 wherein each of said transducer elements are independently actuatable, and wherein said focusing step comprises independently actuating said transducer elements.