Thermometric cardiac tissue ablation electrode with ultra-sensitive temperature detection

• US 4,966,597 A
• Filed: 11/04/1988
• Issued: 10/30/1990
• Est. Priority Date: 11/04/1988
• Status: Expired due to Term

• Current Assignee: Sherwood Services AG
• Original Assignee: Eric R. Cosman
• Inventors: Cosman, Eric R.
• Primary Examiner(s): Hindenburg, Max
• Application Number:
  US07/267,211
• Time in Patent Office: 725 Days
• Field of Search: 128/303.13-303.17, 128/736, 128/786, 606/31, 606/41, 606/50
• US Class Current: 606/50
• 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 2017/00097 one of the thermometric elements being an electrode or the heating element
• CPC Class Codes: A61B 2017/00292 mounted on or guided by flexible, e.g. catheter-like, means

Abstract

This invention relates to the construction of a cardiac ablation electrode with a thermosensing detector at one or more positions in the distal tip. The distal tip is uninsulated in contrast to the rest of the flexible length of the electrode to enable radiofrequency (rf) potential to be applied there. This rf potential causes heating of cardiac tissue when the catheter electrode is inserted into the heart via venus pathways. A thermocouple sensor is embedded in the electrode tip with the detection wires running along the catheter to external apparatus for measurement to application of radiofrequency. The thermocouple sensor is integral and at the surface of the distal electrodes for true surface temperature recording with fast response.

Claims

1. An electrode catheter system with temperature control adapted for making radiofrequency heat lesions in a body and particularly the cardiac region and having built-in thermocouple temperature sensor which can sense the temperature of the heated body tissue, said electrode having the shape of a elongated catheter with a distal end that is intended to be directed into the bodily tissue, particularly near the cardiac region to be heated, and a proximal end which is adapted to be connected to an external source of radiofrequency energy and to an external thermocouple temperature monitoring apparatus through a connection means, a portion of the elongated catheter electrode that will be inserted into the body comprising a flexible, tubular structure with an internal lumen and having a longitudinally extending insulating material portion, said electrode having at least one uninsulated conductive tip at its distal end from which, when in use, radiofrequency current will flow to heat surrounding tissue, said electrode having conductive means connecting said uninsulated distal tip to said connection means located near said proximal end of said electrode adapted for connection to an external source of radiofrequency potential, and whereby said internal lumen can be used to insert stylet means so that said catheter can be tunneled deep within the body through blood vessels, whereby when in use, said uninsulated tip will be at said radiofrequency potential, said electrode having a first metal element and a second metal element, both metal elements running from said proximal end to said distal end of said electrode, said two metal elements being the two sides of a thermocouple pair, said two metal elements being embedded within said longitudinally extending insulating material portion and electrically insulated from each other over the length of said electrode except at said distal end, the distal ends of said two metal elements being electrically fused at said distal end of said electrode to form a thermocouple junction in such a way that a portion of each of said distal ends of said two metal elements and a portion of said fused junction are part of an external surface of said uninsulated tip, the proximal ends of said two metal elements near the proximal end of said electrode are so adapted to be connected to an external thermocouple junction potential measuring apparatus;

whereby, when in use, said electrode is inserted into the living body by inserting a stylet into said lumen means within said catheter-shaped electrode, and thus said distal end of said electrode can be worked into the proper position within the blood-carrying structure of the living body, once in position so described, the radiofrequency potential of said uninsulated tip of said electrode will cause a current to flow in and thus heat up the tissue surrounding said uninsulated tip, and said distal portions of said two metal elements and said portion of thermocouple junction which are on the external surface of said uninsulated tip will provide an intimate thermal contact with the heated tissue adjacent to said external surface and thus a reliable measure of the temperature of said adjacent tissue.

2. The electrode of claim 1 wherein said conductive means connecting said uninsulated tip of said rf connection means, a portion of said uninsulated conductive tip and one of said metal thermocouple elements are the same continuous metal structure.

3. The electrode of claim 2 wherein said embedded two metal thermocouple elements are insulated from external contacts from outside of the electrode except at the distal tip and insulated from the internal lumen of the electrode, such that when an insertion stylet is placed within the lumen for insertion of the electrode within the body, said stylet will not contact electrically or mechanically said two metal thermocopule elements.

4. An electrode catheter system with temperature control adapted for making radiofrequency heat lesions in a body and particularly the cardiac region and having built-in thermocouple temperature sensor which can sense the temperature of the heated body tissue, said electrode having the shape of a elongated catheter with a distal end that is intended to be directed into the bodily tissue, particularly near the cardiac region to be heated, and a proximal end which is adapted to be connected to an external source of radiofrequency energy and to an external thermocouple temperature monitoring apparatus through a connection means, a portion of the elongated catheter electrode that will be inserted into the body comprising a flexible structure having a longitudinally extending insulating material portion, said electrode having at least one uninsulated conductive tip at its distal end from which, when in use, radiofrequency current will flow to heat surrounding tissue, said electrode having conductive means connecting said uninsulated distal tip to said connection means located near said proximal end of said electrode adapted for connection to an external source of radiofrequency potential, and whereby said catheter can be tunneled deep within the body through blood vessels, whereby when in use, said uninsulated tip will be at said radiofrequency potential, said electrode having a first metal element and a second metal element, both metal elements running from said proximal end to said distal end of said electrode, said two metal elements being the two sides of a thermocouple pair, said two metal elements being embedded within said longitudinally extending insulating material portion and electrically insulated from each other over the length of said electrode except at said distal end, the distal ends of said two metal elements being electrically fused at said distal end of said electrode to form a thermocouple junction in such a way that a portion of each of said distal ends of said two metal elements and a portion of said fused junction are part of an external surface of said uninsulated tip, the proximal ends of said two metal elements near the proximal end of said electrode are so adapted to be connected to an external thermocouple junction potential measuring apparatus;

whereby, when in use, said electrode is inserted into the living body, and thus said distal end of said electrode can be worked into the proper position within the blood-carrying structures of the living body, once in position so described, the radiofrequency potential of said uninsulated tip of said electrode will cause a current to flow in and thus heat up the tissue surrounding said uninsulated tip, and said distal portions of said two metal elements and said portion of thermocouple junction which are on the external surface of said uninsulated tip will provide an intimate thermal contact with the heated tissue adjacent to said external surface and thus a reliable measure of the temperature of said adjacent tissue.