Method of using endocardial impedance for determining electrode-tissue contact, appropriate sites for arrhythmia ablation and tissue heating during ablation

• US 5,447,529 A
• Filed: 01/28/1994
• Issued: 09/05/1995
• Est. Priority Date: 01/28/1994
• Status: Expired due to Fees

• Current Assignee: Catholic University of America (Catholic University), Philadelphia Heart Institute, Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Original Assignee: Catholic University of America (Catholic University), Philadelphia Heart Institute, Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Inventors: Gottleb, Charles D., Schwartzman, David S., Chang, Isaac, Mirotznik, Mark S., Foster, Kenneth R., Marchlinski, Francis E.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): HUANG, STEPHEN D
• Application Number:
  US08/188,514
• Time in Patent Office: 585 Days
• Field of Search: 128/637, 128/642, 128/662.06, 128/670, 128/692, 128/701, 128/713, 128/654, 128/672, 128/695 R, 128/734, 128/693, 606/41, 607/41, 607/99
• US Class Current: 607/99
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• 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 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/126 bipolar
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• 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 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/40 Applying electric fields by inductive or capacitive coupling microwave apparatus A61N5/00; Applying radio-frequency signals

Abstract

A method of locating infarcted myocardial tissue in a beating heart includes the step of inserting an impedance measuring tip of a catheter into the chamber of the beating heart, particularly the left or right ventricle, and measuring the impedance of the endocardium at various locations within the chamber of the beating heart. The values measured are compared to impedance values with a predetermined range of values to identify an infarcted area of myocardium and distinguish such area from normal myocardium. The measurements are also compared to a range of values for an infarction border zone. In accordance with the invention, the infarction border zone may be located. The infarction border zone is a significant source of arrhythmia, and particularly of ventricular tachycardia. Further, in accordance with the methods of the present invention, the risk of arrhythmia in a beating heart may be substantially reduced or eliminated by ablating endocardium within the infarction border zone utilizing the same catheter tip. Impedance measurements may also be utilized to assess the adequacy of the electrode-tissue contact, particularly in a fluid filled body organ or cavity. Further, the effectiveness of the ablation of the tissue may be determined by determining the degree of heating of the tissue by measuring the change in impedance in the area of ablation.

Claims

1. A method of locating a source of arrhythmia in a beating heart, comprising:

inserting an impedance measuring electrode of a catheter into a chamber of a beating heart;

measuring impedance of endocardium at various locations within the chamber of the beating heart using said electrode of said catheter; and

determining a border zone between normal and infarcted endocardium based upon measured impedance, said border zone being said source.

2. A method in accordance with claim 1, wherein inserting step includes inserting said measuring electrode of said catheter into a left ventricle of the beating heart.

3. A method in accordance with claim 1, wherein inserting step includes inserting said measuring electrode of said catheter into a right ventricle of the beating heart.

10. A method in accordance with claim 1 wherein said step of determining a border zone between normal and infarcted endocardium includes the step of determining three predetermined ranges of impedance values, a highest range of impedance values being normal endocardium, a lowest range of impedance values representing infarcted endocardium and a middle range of impedance values representing said border zone and the source of arrythmia.

4. A method of locating a source of arrythmia and reducing the risk of future arrythmia in a beating heart, comprising:

inserting an electrode of a catheter into a chamber of a beating heart, said electrode being adapted for impedance measuring and ablation;

measuring impedance of endocardium at various locations within the chamber of the beating heart using said electrode of said catheter;

determining a border zone between normal and infarcted endocardium based upon measured impedance; and

using said electrode of said catheter to ablate endocardium in said border zone.

5. A method in accordance with claim 4, wherein inserting step includes inserting said electrode of said catheter into a left ventricle of a beating heart.

6. A method in accordance with claim 4, wherein inserting step includes inserting said electrode of said catheter into a right ventricle of the beating heart.

11. A method in accordance with claim 4 wherein said step of determining a border zone between normal and infarcted endocardium includes the step of determining three predetermined ranges of impedance values, a highest range of impedance values being normal endocardium, a lowest range of impedance values representing infarcted endocardium and a middle range of impedance values representing said border zone.

7. A method of locating a source of arrythmia and infarcted myocardial tissue in a beating heart, comprising:

inserting an impedance measuring electrode of a catheter into a chamber of a beating heart;

measuring impedance of endocardium at various locations within the chamber of the beating heart using said electrode of said catheter; and

comparing the measured impedance values with predetermined ranges of values to identify an infarcted area and an infarct border area of myocardium and distinguishing such areas from normal myocardium.

8. A method in accordance with claim 7, wherein inserting step includes inserting said measuring electrode of said catheter into a left ventricle of the beating heart.

9. A method in accordance with claim 7, wherein inserting step includes inserting said impedance measuring electrode of said catheter into a right ventricle of the beating heart.

12. A method in accordance with claim 7, including the step of establishing predetermined ranges of values to identify an infarcted area and an infarct border area of myocardium.

13. A method in accordance with claim 12 wherein said step of establishing predetermined ranges of values includes the step of measuring the impedance of normal endocardium of a patient being treated and deriving from the normal endocardium impedance values ranges of impedance values for infarcted areas and infarct border areas.

14. A method in accordance with claim 12 wherein said step of establishing predetermined ranges of values to identify the infarcted area and the infarct border area include the step of performing impedance measurements of the endocardium in a plurality of beating hearts and recording ranges of the impedance values for future use.

15. A method of locating infarcted myocardial tissue in a beating heart, comprising:

inserting an impedance measuring electrode of a catheter into a chamber of a beating heart;

measuring impedance of endocardium at various locations within the chamber of the beating heart using said electrode of said catheter; and

comparing measured impedance values with a predetermined range of values to identify an infarcted area of myocardium and distinguishing such area from normal myocardium.

16. A method of locating a border zone separating normal and infarcted myocardium, comprising:

inserting an impedance measuring electrode of a catheter into a chamber of a beating heart;

measuring impedance of endocardium at various locations within the chamber of the beating heart using said electrode of said catheter; and

comparing measured impedance values with a predetermined range of values to identify a border zone separating normal and infarcted myocardium and to distinguish such area from normal and infarcted myocardium.