Acoustic telemetry system and method for monitoring a rejection reaction of a transplanted organ

• US 6,198,965 B1
• Filed: 05/17/1999
• Issued: 03/06/2001
• Est. Priority Date: 12/30/1997
• Status: Expired due to Fees

• Current Assignee: Remon Medical Technologies Ltd. (Boston Scientific Corporation)
• Original Assignee: Remon Medical Technologies Ltd. (Boston Scientific Corporation)
• Inventors: Penner, Avi, Porat, Yariv, Doron, Eyal
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US09/312,760
• Time in Patent Office: 659 Days
• Field of Search: 600/547, 600/508, 600/510
• US Class Current: 600/547
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/413 Monitoring transplanted tissue or organ, e.g. for possible rejection reactions after a transplant
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00

Abstract

A telemetry system for monitoring a rejection reaction of a transplanted organ being transplanted within a patient'"'"'s body is provided. The telemetry system includes (a) a telemetry control unit located outside the body of the patient; and (b) a telemetry monitoring unit implanted within the body of the patient, the telemetry monitoring unit including: (i) at least one acoustic transducer being for receiving an acoustic signal from the telemetry control unit and converting the acoustic signal into a first electrical signal, the at least one acoustic transducer further being for receiving a second electrical signal and converting the second electrical signal into a transmitted acoustic signal receivable by the telemetry monitoring unit; and (ii) a plurality of electrodes positionable in intimate contact with, or deep within, the transplanted organ and being in communication with the at least one acoustic transducer, the plurality of electrodes being for passing the first electrical signal through the transplanted organ for monitoring the electrical impedance thereof and further being for relaying the second electrical signal corresponding to the electrical impedance to the at least one acoustic transducer so as to enable the monitoring of the presence or absence of the rejection reaction.

Claims

1. A telemetry system for monitoring a rejection reaction of a transplanted organ being transplanted within a patient'"'"'s body, the telemetry system comprising:

(a) a telemetry control unit located outside the body of the patient; and

(b) a telemetry monitoring unit implanted within the body of the patient, said telemetry monitoring unit including;

(i) at least one acoustic transducer being for receiving an acoustic signal from said telemetry control unit and converting said acoustic signal into a first electrical signal, said at least one acoustic transducer further being for receiving a second electrical signal and converting said second electrical signal into a transmitted acoustic signal receivable by said telemetry monitoring unit; and

(ii) a plurality of electrodes positionable in intimate contact with, or deep within, the transplanted organ and being in communication with said at least one acoustic transducer, said plurality of electrodes being for passing said first electrical signal through the transplanted organ for monitoring the electrical impedance thereof and further being for relaying said second electrical signal corresponding to said electrical impedance to said at least one acoustic transducer so as to enable the monitoring of the presence or absence of the rejection reaction.

2. The monitoring system of claim 1, wherein the transplanted organ is an internal organ.

3. The monitoring system of claim 2, wherein said internal organ is selected from the group consisting of a heart, a kidney, a liver and a lung.

4. The monitoring system of claim 1, wherein each of said at least one acoustic transducer includes:

(i) a cell member having a cavity;

(ii) a substantially flexible piezoelectric layer attached to said cell member, said piezoelectric layer having an external surface and an internal surface, said piezoelectric layer featuring such dimensions so as to enable fluctuations thereof at its resonance frequency upon impinging of an external acoustic wave; and

(iii) a first electrode attached to said external surface and a second electrode attached to said internal surface.

5. The monitoring system of claim 1, wherein said first electrical signal is passed through the transplanted organ by a first pair of said plurality of electrodes and further wherein said second electrical signal is relayed by a second pair of said plurality of electrodes.

6. The monitoring system of claim 5, wherein said first pair of said plurality of electrodes and said second pair of said plurality of electrodes are a single pair of electrodes.

7. The monitoring system of claim 1, wherein said first electrical signal is supplied as an alternating electrical current, such that a phase shift of the voltage relative to the current phase indicative of the impedance is relayed by the second electrical signal.

8. The monitoring system of claim 1, wherein said first electrical signal is a substantially square wave pulse electrical current, such that a change in said pulse'"'"'s amplitude and or phase shift of the complex impedance value indicative of the impedance is relayed by the second electrical signal.

9. The monitoring system of claim 8, wherein the height of the leading edges of said square wave pulse are relayed by said second electrical signal and monitored.

10. The monitoring system of claim 8, wherein the steepness of the leading edges of said square wave pulse are relayed by said second electrical signal and monitored.

11. The system of claim 1, wherein said plurality of electrodes are arranged in a grid form.

12. A method of monitoring a rejection reaction of a transplanted organ being transplanted within a patient'"'"'s body, the method comprising the steps of:

(a) implanting a telemetry monitoring unit including a plurality of electrodes and at least one acoustic transducer communicating therewith within a patient'"'"'s body, said plurality of electrodes being in intimate contact with, or deep within, the transplanted organ; and

(b) locating a telemetry control unit located outside, and in intimate contact with, the body of the patient;

(c) generating an acoustic signal via said telemetry control unit, said acoustic signal impinging on said at least one transducer of said telemetry monitoring unit, being transduced into a first electrical signal, being relayed to said plurality of electrodes and being passed through the transplanted organ to thereby provide information pertaining to an impedance of the transplanted organ in a form of a second electrical signal being relayed from said plurality of electrodes to said at least one transducer; and

(d) receiving via said telemetry control unit a second acoustic signal being transmitted thereto by said at least one transducer, said second acoustic signal corresponding to said second electrical signal.

13. The method of claim 12, wherein the transplanted organ is an internal organ.

14. The method of claim 12, wherein said internal organ is selected from the group consisting of a heart, a kidney, a liver and a lung.

15. The method of claim 12, wherein said at least one acoustic transducer includes:

(i) a cell member having a cavity;

(ii) a substantially flexible piezoelectric layer attached to said cell member, said piezoelectric layer having an external surface and an internal surface, said piezoelectric layer featuring such dimensions so as to enable fluctuations thereof at its resonance frequency upon impinging of an external acoustic wave; and

(iii) a first electrode attached to said external surface and a second electrode attached to said internal surface.

16. The method of claim 12, wherein said first electrical signal is passed by a first pair of said plurality of electrodes and further wherein said second electrical signal is relayed by a second pair of said plurality of electrodes.

17. The method of claim 16, wherein said first pair of said plurality of electrodes and said second pair of said plurality of electrodes are a single pair of electrodes.

18. The method of claim 12, wherein said first electrical signal is supplied as an alternating electrical current, such that a phase shift of the voltage relative to the current phase indicative of the impedance is relayed by the second electrical signal.

19. The method of claim 12, wherein said first electrical signal is a substantially square wave pulse electrical current, such that a change in said pulse'"'"'s amplitude and or phase shift of the complex impedance value indicative of the impedance is relayed by the second electrical signal.

20. The method of claim 19, wherein the height of the leading edges of said square wave pulse are relayed by said second electrical signal and monitored.

21. The monitoring system of claim 19, wherein the steepness of the leading edges of said square wave pulse are relayed by said second electrical signal and monitored.