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.
A method for assessing adequacy of electrode-tissue contact in a fluid filled organ, comprising the steps of: inserting an impedance measuring electrode mounted on a catheter into a fluid filled organ; measuring a non-zero impedance numerical value when the electrode is in fluid to establish a measured base line impedance numerical value; comparing the measured base line impedance numerical value to a predetermined non-zero range of numerical values of impedance for the fluid; measuring impedance numerical values as the electrode comes into contact with organ tissue; comparing measured impedance numerical values to a predetermined range of impedance numerical values of the organ tissue; and determining the adequacy of electrode-tissue contact by comparing said measured impedance numerical values with said predetermined ranges of impedance numerical values.
Claim 2
Independent Claim
125 words
A method for assessing adequacy of electrode-tissue contact in a fluid filled organ, comprising the steps of: inserting an impedance measuring electrode mounted on a catheter into a fluid filled organ; measuring a non-zero impedance numerical value when the electrode is in fluid to establish a measured base line impedance numerical value; comparing the measured base line impedance numerical value to a predetermined non-zero range of numerical values of impedance for the fluid; measuring impedance numerical values as the electrode comes into contact with organ tissue; comparing measured impedance numerical values to a predetermined range of impedance numerical values of the organ tissue; and determining the adequacy of electrode-tissue contact by comparing said measured impedance numerical values with said predetermined ranges of impedance numerical values.
Claim 3
Dependent Claim
24 words
A method in accordance with claim 1, wherein said inserting step comprises inserting the impedance measuring electrode into a chamber of a beating heart.
Claim 4
Independent Claim
122 words
A method for assessing adequacy of electrode-tissue contact in a beating heart, comprising the steps of: inserting an impedance measuring electrode mounted on a catheter into a blood vessel connected to the beating heart; measuring the impedance in blood in a blood vessel outside of the beating heart; positioning the catheter electrode using fluoroscopy at least one stable catheter placement site on endocardium; measuring the impedance at said at least one stable catheter placement site with the catheter electrode placed against endocardium as monitored by fluoroscopy to determine a range of impedance values corresponding to adequate electrode-tissue contact; and determining from said two measuring steps whether the electrode is in contact with the endocardium in subsequent placements based on said determined values.
Claim 5
Independent Claim
122 words
A method for assessing adequacy of electrode-tissue contact in a beating heart, comprising the steps of: inserting an impedance measuring electrode mounted on a catheter into a blood vessel connected to the beating heart; measuring the impedance in blood in a blood vessel outside of the beating heart; positioning the catheter electrode using fluoroscopy at least one stable catheter placement site on endocardium; measuring the impedance at said at least one stable catheter placement site with the catheter electrode placed against endocardium as monitored by fluoroscopy to determine a range of impedance values corresponding to adequate electrode-tissue contact; and determining from said two measuring steps whether the electrode is in contact with the endocardium in subsequent placements based on said determined values.