Cardiac monitoring system and method with multiple implanted transponders

• US 20020147405A1
• Filed: 03/28/2002
• Published: 10/10/2002
• Est. Priority Date: 04/05/2001
• Status: Active Grant

• Current Assignee: Kenergy, Inc.
• Original Assignee: Kenergy, Inc.
• Inventors: Denker, Stephen, Bulkes, Cherik, Beutler, Arthur J.
• Granted Patent: US 6,592,518 B2
• Time in Patent Office: Days
• US Class Current: 600/508
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372

Abstract

A plurality of radio frequency semi-passive transponders are attached to an animal'"'"'s organ, such as the heart. Each semi-passive transponder may be attached to the surface of the organ or mounted on a stent that is implanted in a blood vessel of the organ. An interrogator periodically sends a signal to each semi-passive transponder which reacts by transmitting a reply signal. The interrogator processes the reply signals to derive information regarding activity of the organ. In one embodiment, the position of each semi-passive transponder is determined from the reply signals, thereby enabling information about organ movement and volume change to be derived. In another embodiment, data from a sensor on the semi-passive transponder is sent via the reply signal.

Claims

1. An apparatus for monitoring a physiological characteristic of an animal, that apparatus comprising:

at least one transponder adapted to be implanted in the animal and producing a reaction in response to receipt of an interrogation signal that is transmitted wirelessly through the animal;

a transmitter for transmitting the interrogation signal wirelessly through the animal;

a receiver for detecting a reaction of each transponder to the interrogation signal; and

a controller which determines the physiological characteristic in response to the reaction detected for each transponder.

2. The apparatus as recited in claim 1 wherein there are a plurality of transponders attached to the organ in a non-planar array.

3. The apparatus as recited in claim 2 wherein the controller processes the reaction of each of the plurality of transponders to determine a position of each transponder within the animal.

4. The apparatus as recited in claim 2 wherein the controller derives a value for the volume of the organ from the position of each transponder.

5. The apparatus as recited in claim 4 wherein the controller determines cardiac output from changes in the volume of the organ.

6. The apparatus as recited in claim 1 wherein the reaction of each transponder in response to the interrogation signal comprises transmitting a reply signal wirelessly through the animal.

7. The apparatus as recited in claim 6 wherein the controller determines a position of each transponder in response to an intensity of the reply signal from each transponder.

8. The apparatus as recited in claim 6 wherein the at least one transponder has sensors for detecting the physiological characteristic and transmits information regarding the physiological characteristic via the reply signal.

9. The apparatus as recited in claim 1 wherein each transponder is formed on a stent adapted to be implanted in a blood vessel of the animal.

10. An apparatus for monitoring activity of a heart in an animal, that apparatus comprising:

a transmitter which transmits a plurality of interrogation signals wirelessly through the animal;

a plurality of transponders adapted to be attached to the heart and each transponder being responsive to a unique one of the interrogation signals by transmitting a reply signal wirelessly through the animal;

a receiver for detecting the reply signal from each of the plurality of transponders; and

a controller which determines a position of each of the plurality of transponders in response to the reply signals.

11. The apparatus as recited in claim 10 wherein each transponder is formed on a stent adapted to be implanted in a blood vessel of the heart.

12. The apparatus as recited in claim 10 wherein the controller determines movement of the heart from changes in positions of the plurality of transponders.

13. The apparatus as recited in claim 10 wherein the controller derives a value for the volume of the heart from the positions of the plurality of transponders.

14. The apparatus as recited in claim 13 wherein the controller determines cardiac output from changes in the volume of the heart.

15. The apparatus as recited in claim 10 wherein at least one of the plurality of transponders has a sensor that detects a physical characteristic and transmits information regarding the physical characteristic via the reply signal.

16. The apparatus as recited in claim 15 wherein the at least one of the plurality of transponders is formed on a stent adapted to be implanted in a blood vessel and the sensor provides information regarding a pressure drop across the stent.

17. The apparatus as recited in claim 15 wherein the sensor provides information regarding electrical activity of the heart.

19. The apparatus as recited in claim 18 wherein processing the reply signal derives information regarding movement of the organ.

20. The apparatus as recited in claim 18 wherein processing the reply signal derives information regarding changes in volume of the organ.

21. The apparatus as recited in claim 18 further comprising sensing a physical characteristic of the organ;

transmitting information about that physical characteristic with the reply signal; and

wherein processing the reply signal obtain the information about that physical characteristic.

18. A method for monitoring activity of an organ in an animal, that method comprising:

attaching at least one transponder to the organ;

interrogating the transponder with a wirelessly transmitted interrogation signal;

the transponder reacting to the interrogation signal by wirelessly transmitting a reply signal;

receiving the reply signal from the transponder; and

processing the reply signal to derive information regarding the activity of the organ.