Method and a device for measuring physical variables in a living body

• US 20010051769A1
• Filed: 03/20/2001
• Published: 12/13/2001
• Est. Priority Date: 03/21/2000
• Status: Active Grant

• Current Assignee: St. Jude Medical Coordination Center BVBA (Abbott Laboratories Incorporated)
• Original Assignee: Radi Medical Systems AB (Abbott Laboratories Incorporated)
• Inventors: Tenerz, Lars, Smith, Leif, Hoek, Bertil
• Granted Patent: US 6,615,067 B2
• Time in Patent Office: Days
• US Class Current: 600/381
• CPC Class Codes: A61B 5/0008 Temperature signals
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/6851 Guide wires
• CPC Class Codes: A61M 2025/0002 with a pressure sensor at the distal end
• CPC Class Codes: A61M 2230/30 Blood pressure A61M2230/04 takes precedence
• CPC Class Codes: A61M 2230/50 Temperature
• CPC Class Codes: A61M 25/09 Guide wires

Abstract

A guide wire, for measuring a physiological variable inside a living body, having few conductors is provided. The guide wire is provided with a sensor (14) for monitoring the physical variable and for forming an output signal characteristic for the value of the physical variable. The sensor is connected to a first electrical potential of an electronic unit (22) via an electrical wire (11) extending along the guide wire. An internal body electrode (17) is connected to the sensor (14) and is in contact with body fluids surrounding the sensor circuit. The guide wire (10) is inserted into a vessel of the body (25), and a second electrode (21) is applied near the internal body electrode, and the sensor circuit is powered by a second potential of the electronic unit (22) via a part of the body.

Claims

1. A system for intravascular measurement of a physiological variable inside a living body, including a powering electronic unit (22;

222;

332), an electrical wire (11) having a distal end for insertion into the living body and a proximal end for electrical connection to the electronic unit (22;

222;

332), and a sensor (14;

502;

406) connected to the proximal end of the electrical wire, characterised in that

an internal body electrode (17;

117, 113B;

317;

405) is connected to the sensor (14;

502;

406), said internal body electrode having a portion for physical and electrical contact with body tissue when disposed at the site of measurement; and

a second electrode (21, 24;

221;

32) for electrical connection to the electronic unit (22;

222;

332), said second electrode having a portion for electrical contact with a second part of the living body,

said system thus being adapted to transfer an electrical signal through said electrodes via the body tissue.

2. The system according to

claim 1

, wherein the electrical wire (11) for insertion into the body is a core wire extending through a guide wire.

3. The system according to

claim 1

or

2

, wherein the electronic unit (22;

222;

332) comprises an AC power source to power the sensor with an AC voltage via the body tissue.

4. The system according to

claim 3

, wherein said AC voltage is within the range of 2-10 V, and is of a frequency in the range of 100 kHz-1 MHz.

5. The system according to

claim 1

or

2

, wherein the electronic unit comprises an DC voltage supply.

6. The system according to anyone of the previous claims, wherein said second electrode is a second electrical wire (31) having an electrode portion (32) at its distal end for insertion into the living body.

7. A guide wire for intravascular measurement of a physiological variable inside a living body, including an electrically conducting wire (11) extending along the guide wire and a sensor (14;

502;

406) at the distal end of the guide wire connected to the electrically conducting wire (11), characterised in that

an internal body electrode (17;

117, 113B;

317;

405) is connected to the sensor (14;

502;

406), said internal body electrode having a portion for physical and electrical contact with body tissue when disposed at the site of measurement.

8. The guide wire according to

claim 7

, wherein the electrically conducting wire (11) is a core wire extending through the guide wire.

9. The guide wire according to

claim 7

or

8

, wherein a coil (113B) disposed around the distal end of said guide wire is connected to the sensor to act as said internal body electrode.

10. The guide wire (210) according to anyone of claims 7 or 9, characterised in that a second electrical wire (31) is attached thereto to extend along the guide wire, said second electrical wire having an electrode portion (32) near the distal end of the guide wire for physical and electrical contact with body tissue.

11. A method for intravascular measurement of a physiological variable inside a living body, wherein a guide wire having a sensor (14;

502;

406) responsive to the physiological variable at its distal end is inserted into the body to place the sensor at the site of measurement, the sensor being connected to an electrical wire (11) having a proximal end outside of the body, characterised by

selecting a guide wire according to anyone of

claims 7

to

9

,

electrically connecting a second electrode to the body of the patient, connecting the electrical wire (11) and the second electrode (21, 24;

221) to an electronic unit (22;

222) in order to power the sensor via the body tissue of the patient, and

registering a signal from the sensor via said electrodes, said signal representing the physiological variable.

12. The method according to

claim 11

, wherein the step of connecting a second electrode comprises placing said electrode on the skin of the patient.

13. The method according to

claim 11

, wherein the step of connecting a second electrode comprises disposing said electrode inside the body of the patient along with the sensor.