Microwave Monitoring of Heart Function

• US 20110130800A1
• Filed: 04/14/2010
• Published: 06/02/2011
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: ZOLL Medical Israel Limited (Asahi Kasei Corporation)
• Original Assignee: Kyma Medical Technologies Ltd. (Asahi Kasei Corporation)
• Inventors: Weinstein, Uriel, Bernstein, Assaf, Cohen, Eyal
• Granted Patent: US 8,989,837 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2562/0217 Electrolyte containing
• CPC Class Codes: A61B 2562/14 Coupling media or elements to improve sensor contact with skin or tissue
• CPC Class Codes: A61B 2562/166 the sensor is mounted on a specially adapted printed circuit board
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 8/085 for locating body or organic structures, e.g. tumours, calculi, blood vessels, nodules
• CPC Class Codes: A61B 8/4254 using sensors mounted on the probe
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone

Abstract

Diagnostic apparatus includes a plurality of antennas, which are configured to be disposed at different, respective locations on a thorax of a living body so as to direct radio frequency (RF) electromagnetic waves from different, respective directions toward a heart in the body and to output RF signals responsively to the waves that are scattered from the heart. Processing circuitry is configured to process the RF signals over time so as to provide a multi-dimensional measurement of a movement of the heart.

Claims

1. Diagnostic apparatus, comprising:

a plurality of antennas, which are configured to be disposed at different, respective locations on a thorax of a living body so as to direct radio frequency (RF) electromagnetic waves from different, respective directions toward a heart in the body and to output RF signals responsively to the waves that are scattered from the heart; and

processing circuitry, which is configured to process the RF signals over time so as to provide a multi-dimensional measurement of a movement of the heart.

2. The apparatus according to claim 1, wherein the plurality of antennas comprises at least three antennas, and wherein the respective locations are chosen so as to at least partially surround the thorax.

3. The apparatus according to claim 1, wherein each antenna has a front surface, which is configured to contact an outer surface of the body and comprises a planar antenna element.

4. The apparatus according to claim 3, wherein the planar antenna element comprises a conductive spiral.

5. The apparatus according to claim 3, wherein each antenna comprises a ground plane behind the front surface with an electromagnetic band gap (EBG) structure between the ground plane and the front surface.

6. The apparatus according to claim 3, and comprising a dielectric gel, which is applied between the antenna and the outer surface of the body.

7. The apparatus according to claim 1, wherein each antenna is configured to contact an outer surface of the body, and wherein the processing circuitry is configured to receive and process an electrocardiogram signal received from the body by at least one of the antennas, in addition to the RF signals.

8. The apparatus according to claim 1, and comprising excitation circuitry, which is coupled to select different ones of the antennas to serve as transmitting and receiving antennas and to apply a RF excitation waveform at multiple different frequencies to the selected transmitting antennas, while the processing circuitry receives the RF signals from the selected receiving antennas, wherein the transmitting and receiving antennas and the different frequencies are selected according to a predetermined temporal pattern.

9. The apparatus according to claim 8, wherein the excitation circuitry comprises:

a driver circuit, which is configured to generate the RF excitation waveform with a variable frequency; and

a switching matrix, which is configured to select sets of the antennas in alternation, each set comprising at least one transmitting antenna and at least one receiving antenna, and for each selected set, to couple the driver circuit to excite the at least one transmitting antenna at a selected frequency while coupling the processing circuitry to receive the RF signals from the at least one receiving antenna.

10. The apparatus according to claim 1, wherein the plurality of antennas comprises at least first and second antennas disposed on respective opposite sides of the thorax, so that the second antenna receives the RF electromagnetic waves transmitted by the first antenna after passage of the RF electromagnetic waves through at least one lung in the body, and

wherein the processor is configured to process the RF signals output by the second antenna so as to assess an amount of fluid accumulation in the at least one lung.

11. The apparatus according to claim 1, and comprising at least one pacing electrode, wherein the processing circuitry is configured to drive the at least one pacing electrode so as to pace the heart responsively to the measurement of the movement of the heart.

12. The apparatus according to claim 1, wherein the antennas are configured to sweep the RF electromagnetic waves over multiple different frequencies so that the RF signals output by the antennas create an ultra-wideband signal.

13. The apparatus according to claim 1, wherein the processing circuitry is configured to compare the measure of the movement of the heart before, during and after heart stress.

14. Diagnostic apparatus, comprising:

an antenna, which is configured to be disposed on a thorax of a living body so as to direct radio frequency (RF) electromagnetic waves toward a heart in the body while sweeping the waves over multiple different frequencies and to output an ultra-wideband RF signal responsively to the waves that are scattered from the heart; and

processing circuitry, which is configured to process the RF signal over time so as to provide a measurement of a movement of the heart.

15. The apparatus according to claim 14, and comprising a package, which contains the antenna and the processing circuitry and is configured to be affixed as a patch to an outer surface of the body.

16. The apparatus according to claim 15, and comprising a conductive element associated with the package, which is configured to receive electrocardiogram (ECG) signals from the outer surface of the body.

17. The apparatus according to claim 15, and comprising a wireless communication interface for communicating with a remote console.

18. Diagnostic apparatus, comprising:

one or more antennas, which are configured to be disposed on a thorax of a living body so as to direct radio frequency (RF) electromagnetic waves through a lung in the body and to output RF signals responsively to the waves that have passed through the lung; and

processing circuitry, which is configured to process the RF signals over time so as to measure RF path characteristic of the RF electromagnetic waves and, based on the path characteristic, to assess a fluid content of the lung.

19. The apparatus according to claim 18, wherein the processing circuitry is configured to measure a change in the path characteristic over one or more respiratory cycles of the lung, and to assess the fluid content responsively to the change.

20. The apparatus according to claim 18, wherein the path characteristic comprises an effective RF path length of the RF electromagnetic waves through the body.

21. The apparatus according to claim 20, wherein the processing circuitry is configured to receive a measure of a physical distance traversed by the RF electromagnetic waves through the thorax, and to compare the effective RF path length to the physical distance in order to assess the amount of the fluid accumulation.

22. The apparatus according to claim 21, wherein the one or more antennas comprise a transmitting antenna at a first location on a first side of the thorax, which transmits the RF electromagnetic waves through the lung, and a receiving antenna, which receives the waves that have passed through the lung at a second location on a second side of the thorax, opposite the first side, and wherein the physical distance is measured between the first and second locations.

23. The apparatus according to claim 21, wherein the one or more antennas comprise at least one antenna that is configured to direct the RF electromagnetic waves through the lung toward a heart in the body, and to output the RF signals responsively to the RF electromagnetic waves reflected from the heart.

24. The apparatus according to claim 23, and comprising an ultrasonic transducer, which is adjacent to the at least one antenna and is configured to direct ultrasonic waves toward the heart and receive the ultrasonic waves reflected from the heart so as to provide a measure of the physical distance.

25. The apparatus according to claim 18, wherein the path characteristic comprises an amplitude of the RF signals.

26. Diagnostic apparatus, comprising:

an antenna unit, which has a front surface configured to be brought into contact with an outer surface of a living body and which comprises;

a planar antenna element, which is configured to direct radio frequency (RF) electromagnetic waves from the front surface into the body and to output RF signals responsively to the waves that are scattered from within the body; and

a conductive element, which is configured to receive electrocardiogram (ECG) signals from the outer surface of the body;

a cable, which is connected to the antenna unit so as to communicate with the planar antenna element and the conductive element; and

processing circuitry, which is connected to the cable so as to receive and process the RF and ECG signals.

27. The apparatus according to claim 26, wherein the planar antenna element comprises a conductive spiral.

28. The apparatus according to claim 26, wherein the antenna unit comprises a ground plane behind the front surface and an electromagnetic band gap (EBG) structure between the ground plane and the front surface.

29. The apparatus according to claim 26, and comprising a diplexer coupled between the cable and the processing circuitry for separating the RF signals from the ECG signals.

30. The apparatus according to claim 26, and comprising a gel configured to be spread between the front surface and the outer surface of the body.

31. The apparatus according to claim 26, wherein the antenna unit comprises an adhesive patch for attachment to the body.

32. The apparatus according to claim 26, wherein the antenna unit is configured to be worn on the body as part of a garment.

33. The apparatus according to claim 26, wherein the antenna unit is coated with metal and electrolytes.

34. Diagnostic apparatus, comprising:

an antenna unit, which has a front surface configured to be brought into contact with an outer surface of a living body and which comprises;

a planar antenna element, which is formed on the front surface and is configured to direct radio frequency (RF) electromagnetic waves into the body and to output RF signals responsively to the waves that are scattered from within the body;

a ground plane behind the front surface; and

an electromagnetic band gap (EBG) structure between the ground plane and the front surface; and

processing circuitry, which is coupled to the antenna unit so as to receive and process the RF signals.

35. The apparatus according to claim 34, wherein the planar antenna element comprises a conductive spiral.

36. Therapeutic apparatus, comprising:

at least one pacing electrode, configured to apply a pacing signal to a heart in a living body;

one or more antennas, which are configured to be disposed on a thorax of the body so as to direct radio frequency (RF) electromagnetic waves toward the heart and to output RF signals responsively to the waves that are scattered from the heart; and

processing circuitry, which is configured to process the RF signals over time so as to measure a movement of the heart and to drive the at least one pacing electrode so as to pace the heart responsively to the measured movement.

37. A method for diagnosis, comprising:

directing radio frequency (RF) electromagnetic waves from a plurality of antennas, which are disposed at different, respective locations on a thorax of a living body, toward a heart in the body from different, respective directions, and outputting RF signals responsively to the waves that are scattered from the heart; and

processing the RF signals over time so as to provide a multi-dimensional measurement of a movement of the heart.

38. The method according to claim 37, wherein the plurality of antennas comprises at least three antennas, and wherein the respective locations are chosen so as to at least partially surround the thorax.

39. The method according to claim 37, wherein each antenna has a front surface, which is configured to contact an outer surface of the body and comprises a planar antenna element.

40. The method according to claim 39, wherein the planar antenna element comprises a conductive spiral.

41. The method according to claim 39, wherein each antenna comprises a ground plane behind the front surface with an electromagnetic band gap (EBG) structure between the ground plane and the front surface.

42. The method according to claim 39, and comprising receiving from at least one of the antennas, in addition to the RF signals, an electrocardiogram signal from the body.

43. The method according to claim 37, wherein directing the RF electromagnetic waves comprises selecting different ones of the antennas to serve as transmitting and receiving antennas, and applying a RF excitation waveform at multiple different frequencies to the selected transmitting antennas, while processing the RF signals received from the selected receiving antennas, wherein the transmitting and receiving antennas and the different frequencies are selected according to a predetermined temporal pattern.

44. The method according to claim 37, wherein the plurality of antennas comprises at least first and second antennas disposed on respective opposite sides of the thorax, so that the second antenna receives the RF electromagnetic waves transmitted by the first antenna after passage of the RF electromagnetic waves through at least one lung in the body, and

wherein processing the RF signals comprises processing the RF signals output by the second antenna so as to assess an amount of fluid accumulation in the at least one lung.

45. The method according to claim 37, and comprising pacing the heart responsively to the measurement of the movement of the heart.

46. The method according to claim 37, wherein processing the RF signals over time comprises measuring the movement of the heart before, during and after stress.

47. A method for diagnosis, comprising:

directing radio frequency (RF) electromagnetic waves from an antenna, which is disposed on a thorax of a living body, toward a heart in the body while sweeping the waves over multiple different frequencies, and outputting an ultra-wideband RF signal responsively to the waves that are scattered from the heart; and

processing the RF signal over time so as to provide a measurement of a movement of the heart.

48. A method for diagnosis, comprising:

directing radio frequency (RF) electromagnetic waves from one or more antennas disposed on a thorax of a living body so that the waves pass through a lung in the body, and outputting RF signals responsively to the waves that have passed through the lung; and

processing the RF signals over time so as to measure a RF path characteristic of the RF electromagnetic waves and, based on the path characteristic, to assess a fluid content of the lung.

49. The method according to claim 48, wherein processing the RF signals comprises measuring a change in the path characteristic over one or more respiratory cycles of the lung, and assessing the fluid content responsively to the change.

50. The method according to claim 48, wherein the path characteristic comprises an effective RF path length of the RF electromagnetic waves through the body.

51. The method according to claim 50, and comprising measuring a physical distance traversed by the RF electromagnetic waves through the thorax, and comparing the effective RF path length to the physical distance in order to assess the amount of the fluid accumulation.

52. The method according to claim 51, wherein the one or more antennas comprise a transmitting antenna at a first location on a first side of the thorax, which transmits the RF electromagnetic waves through the lung, and a receiving antenna, which receives the waves that have passed through the lung at a second location on a second side of the thorax, opposite the first side, and wherein the physical distance is measured between the first and second locations.

53. The method according to claim 51, wherein the one or more antennas comprise at least one antenna that is configured to direct the RF electromagnetic waves through the lung toward a heart in the body, and to output the RF signals responsively to the RF electromagnetic waves reflected from the heart.

54. The method according to claim 53, and comprising directing ultrasonic waves toward the heart and receiving the ultrasonic waves reflected from the heart at a location adjacent to the at least one antenna so as to provide a measure of the physical distance.

55. A method for diagnosis, comprising:

bringing a front surface of an antenna unit into contact with an outer surface of a living body, the antenna unit comprising;

a planar antenna element; and

a conductive element, which is configured to receive electrocardiogram (ECG) signals from the outer surface of the body;

driving the planar antenna element to direct radio frequency (RF) electromagnetic waves from the front surface into the body and to output RF signals responsively to the waves that are scattered from within the body; and

receiving and processing both the RF and the ECG signals from the antenna unit.

56. The method according to claim 55, wherein the planar antenna element comprises a conductive spiral.

57. The method according to claim 55, wherein the antenna unit comprises a ground plane behind the front surface and an electromagnetic band gap (EBG) structure between the ground plane and the front surface.

58. The method according to claim 55, and comprising spreading a gel between the front surface and the outer surface of the body.

59. A therapeutic method, comprising:

directing radio frequency (RF) electromagnetic waves toward a heart in a living body from one or more antennas disposed on a thorax of the body, and outputting RF signals responsively to the waves that are scattered from the heart;

processing the RF signals over time so as to measure a movement of the heart; and

pacing the heart responsively to the measured movement.