SYSTEM AND METHOD FOR NON-INVASIVE INSTANTANEOUS AND CONTINUOUS MEASUREMENT OF CARDIAC CHAMBER VOLUME.

• US 20100179421A1
• Filed: 05/23/2008
• Published: 07/15/2010
• Est. Priority Date: 05/24/2007
• Status: Active Grant

• Current Assignee: LifeWave Biomedical, Inc.
• Original Assignee: LifeWave, Inc.
• Inventors: Tupin, Joe
• Granted Patent: US 8,463,361 B2
• Time in Patent Office: Days
• US Class Current: 600/426
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 6/507 for determination of haemodynamic parameters, e.g. perfusion CT
• CPC Class Codes: A61B 6/508 for non-human patients

Abstract

A system and method for non-invasive and continuous measurement of cardiac chamber volume and derivative parameters including stroke volume, cardiac output and ejection fraction comprising an ultrawideband radar system having a trans-mitting and receiving antenna for applying ultrawideband radio signals to a target area of a subject'"'"'s anatomy wherein the receiving antenna collects and transmits signal returns from the target area which are then delivered to a data processing unit, such as an integrated processor or PDA, having software and hardware used to process the signal returns to produce a value for cardiac stroke volume and changes in cardiac stroke volume supporting multiple diagnostic requirements for emergency response and medical personnel whether located in the battlefield, at a disaster site or at a hospital or other treatment facility.

Claims

1. A medical device for determining a change in the spatial configuration of a heart, comprising:

at least one antenna adapted to be located adjacent a portion of the heart; and

a sensing unit capable of resolving a change in reflected signals, wherein said sensing unit of the medical device is capable of resolving a change in reflected signals that are functionally related to a change in cardiac ventricular volume.

2. A medical device according to claim 1 wherein the device is located external to the body.

3. A medical device, according to claim 1, wherein said sensing unit further comprises:

a substrate and a plurality of antennae mounted to said substrate in a pattern and being capable of both transmitting and receiving radiofrequency signals.

4. A medical device according to claim 1, wherein the reflected signals are derivative of an earlier transmitted ultrawideband signal.

5. A medical device according to claim 1, wherein the reflected signals are derivative of an earlier transmitted ultrawideband signal having a frequency band extending from 1 GHz to 15 GHz.

6. A medical device according to claim 1, wherein the reflected signals are derivative of an earlier transmitted ultrawideband signal having a frequency band extending from 3.1 GHz to 10.6 GHz.

7. A medical device according to claim 6 wherein the transmitted ultrawideband signal is compliant with applicable FCC regulations.

8. A medical device according to claim 1 wherein the device is adapted to collect data from the heart.

9. A medical device, according to claim 8, wherein the medical device is adapted to collect said data from a targeted portion of the heart.

10. A medical device according to claim 9 wherein said targeted portion is selected from a group consisting of the left ventricle, right ventricle, left atrium, right atrium, mitral valve, pulmonary valve, aortic valve, and tricuspid valve.

11. A medical device, comprising:

a sensing unit including a control unit, a radar transceiver, and at least one antenna, said at least one antenna being adapted to be located adjacent a portion of a heart to measure dynamic motion of a targeted portion of the heart.

12. A medical device according to claim 11 wherein said control unit drives said radar transceiver and said radar transceiver transmits radiofrequency energy at said targeted portion and said radar transceiver receives reflections of said transmitted radiofrequency energy from said targeted portion and said at least one antenna couples the radiofrequency energy between said transceiver and said targeted portion.

13. A medical device according to claim 11 wherein said sensing unit further comprises software configured to cause said sensing unit to be capable of resolving a change in a spatial configuration of the heart.

14. A medical device according to claim 11 wherein said control unit drives said transceiver to transmit radiofrequency energy at a target and receive reflections of radiofrequency energy from the target to create a coupling of energy between said transceiver and the target.

15. A medical device according to claim 13 wherein said change in spatial configuration is functionally related to a change in ventricular volume.

16. A medical device, according to claim 11, wherein said sensing unit further comprises:

a substrate;

said at least one antenna mounted to said substrate and being capable of sensing a reflected signal; and

a plurality of conductors extending from said at least one antenna and electrically coupled with said control unit.

17. A medical device, according to claim 11, wherein said sensing unit further comprises:

a substrate;

a plurality of antennae mounted to said substrate in a pattern and being capable of sensing reflected signals received by said plurality of antennae; and

a plurality of conductors extending from said plurality of antennae and electrically coupled with said sensing unit.

18. A medical device, according to claim 11, wherein said at least one antenna is adapted to be located on a subject'"'"'s chest adjacent a portion of the heart.

19. A medical device, according to claim 11, wherein said at least one antenna is adapted to be located in close proximity to a subject'"'"'s sternum within a five centimeter radius of a center point of the sternum so as to collect strong reflected signals caused by the beating of the heart.

20. A non-invasive system for determining dynamic physiologic and structural anatomic data from a subject comprising an ultrawideband radar system having at least one transmitting and receiving antenna for applying ultrawideband signals to a target area of the subject'"'"'s anatomy wherein said receiving antenna collects and transmits signal returns from said target area which are then delivered to a data processing and control unit having software and hardware used to process said signal returns to produce a value for said dynamic physiologic and structural anatomic data.

21. A system according to claim 20 wherein said ultrawideband signals are transmitted in a frequency spectrum from 1 GHz to 15 GHz.

22. A system according to claim 20 wherein said ultrawideband signals are transmitted in a manner compliant with FCC regulations in a frequency spectrum from 3.1 GHz to 10.6 GHz.

23. A system according to claim 20 wherein said dynamic physiologic and structural anatomic data is related to cardiac function.

24. A system according to claim 20 wherein said dynamic physiologic and structural anatomic data is related to a change in the spatial configuration of a heart.

25. A system according to claim 20 wherein said dynamic physiologic and structural anatomic data is related to cardiac function and provides a qualitative assessment of changes in any of chamber volume, stroke volume, cardiac output and ejection fraction.

26. A system according to claim 20 wherein said dynamic physiologic and structural anatomic data is related to cardiac function and provides a quantitative assessment of any of chamber volume, stroke volume, cardiac output and ejection fraction.

27. A method for determining changes in cardiac chamber volume in a body wherein an ultrawideband medical radar transceiver, including a transmitter and a receiver and a signal processor integrated with software elements in conjunction with a central processing unit are used according to the following steps:

a. said transceiver transmits a series of electromagnetic pulses into a body;

b. said electromagnetic impulses encounter a boundary between different biological substances in the body;

c. small amounts of incident energy from said electromagnetic pulses encountering the boundary are reflected back towards said receiver as raw reflections where said raw reflections are captured and pre-processed by said receiver;

d. said receiver captures a plurality of said raw reflections using a high speed sample and hold circuit where capture time for a sample of said raw reflections is set equal to a round trip time of flight from said transmitter to one or more depth ranges of interest and back to said receiver;

e. said plurality of sampled reflections from said depth ranges of interest are integrated to form an integrated signal;

f. said integrated signal is filtered to minimize irrelevant high frequency noise so as to avoid corruption of desired data related to tracking instantaneous cardiac chamber volume;

g. said integrated signal is amplified and passed through a low-pass filter to prevent signal aliasing prior to digitization;

h. a predetermined number of reflections for a first range of interest are collected and integrated,

i. said receiver sample timing is changed and reflections from a next range of interest are captured,

j. said steps a through i repeated until reflections from an entire range of interest across the cardiac chamber are collected,

k. said step j is then continually repeated to deliver an updated instantaneous measure of cardiac volumetric changes.

28. The method according to claim 27 wherein said boundaries within a target range of interest move with respect to placement of said transceiver'"'"'s antenna, producing a complex series of time-varying reflections, and wherein said complex series of time-varying reflections are continually processed by said signal processor to extract information on the mechanical activity of the heart.

29. The method according to according to claim 28 wherein said signal processor and central processing unit provide calculation of cardiac chamber volume via the additional steps of:

a. said reflections are first range aligned on sweep boundaries;

b. said range-aligned reflections are passed through one or more filters to minimize low frequency noise and static clutter;

c. resultant data associated with all anatomical motion in said range of interest, including cardiac and pulmonary motion, is amplified and coarse quantized using a binary quantizer where the quantizer threshold for a given sweep or row is based on the median value of the resultant data set, resulting in an intermediate black and white image,

d. said intermediate image further refined through the application of one or more 1-dimensional or 2-dimensional filters to remove random speckle noise and increase the sharpness of the image boundary edges, to improve accuracy of measurement of spatial changes in the target range of interest;

e. thereby presenting an image space comprised of various spatial structures changing in time representing both heart wall motion and various noise sources including organs, bones, and stray radiofrequency emissions.

30. The method according to claim 29 wherein said data is further refined via the application of at least one additional metric to delineate and confirm that said spatial structures found in said image space are cardiac wall excursions.

31. The method according to claim 30 wherein said at least one additional metric is cardiac rate wherein the cardiac rate is integrated within said signal processor and is detected via application and processing of said electromagnetic signals, said signal processor calculating the cardiac rate via conversion of an entire swept image space to a predetermined frequency domain using an algorithm, wherein said algorithm identifies and isolates an image region of said entire swept image space containing a strongest cardiac signal, while simultaneously determining a range of depth containing said strongest cardiac signal, wherein said cardiac signal depth and said cardiac signal is used to determine one or more additional metrics.

32. The method according to claim 30 wherein said at least one additional metric is cardiac structure completeness comprising the identification and verification of completeness of a target cardiac structure as said target cardiac structure changes over time by evaluating sustained and rhythmic behavior of said target cardiac structure, wherein said signal processor and said central processing unit in conjunction with said software identifies qualifying signals for further analysis by capturing and prioritizing those said qualifying signals with respect to minimum discontinuities, wherein a conversion process includes a chain coding technique in conjunction with at least one structural morphological technique to minimize signal discontinuities caused by noise loss.

33. The method according to claim 30 wherein said at least one additional metric is the continual and repeated identification and tracking of an ellipsoid characteristic in said image space wherein said ellipsoid characteristic best characterizes the approximate motion of anterior and posterior cardiac walls through time, and, wherein a corollary component of said identification and tracking of said ellipsoid characteristic is the isolation and avoidance of signals having a non-ellipsoid characteristic, wherein said non-ellipsoid signals indicate the likely presence of a non-cardiac signal source.

34. The method according to claim 30 wherein said at least one additional metric is the development of a correlation between the time-domain characteristics of an isolated cardiac range bin identified by a first cardiac rate metric with points identified in said image space that represent minimum, maximum, and zero-crossing points of cardiac wall excursions in said image space as identified by a second and a third metric.

35. The method according to claim 29 wherein said data is further refined via the application of at least one additional metric to delineate and confirm that said spatial structures found in said image space are cardiac wall excursions and not caused by other signal sources, and wherein image regions that meet the requirements of said at least one additional metric are isolated and identified as qualifying candidates for further analysis wherein a likely image region providing a most probable representation of instantaneous cardiac volume is an image region having the strongest characteristic in said at least one additional metric.

36. The method according to claim 35 wherein said likely image region is chosen, minimum and maximum cardiac wall excursions are identified and quantified using prior data acquired and already available from assessment of at least one additional metric, and wherein actual chamber wall displacement is calculated using said minimum and maximum cardiac wall excursions by counting spatial pixels traversed from a minimum point to a maximum point of the cardiac waveform to determine a count of spatial pixels traversed and multiplying said count of pixels by a resolution of the data capture device

37. The method according to claim 36 wherein instantaneous cardiac volume is determined by the additional step of applying presumed dimensions of the target cardiac chamber in conjunction with said minimum and maximum cardiac wall excursions to determine volumetric changes in the target heart chamber.

38. The method according to claim 37 wherein said presumed dimensions of the target cardiac chamber are represented by one or more different shapes, wherein said shapes determine accuracy of calculated chamber volume and derivative stroke volume.

39. The method according to claim 38 wherein one of said one or more different shapes is a simplified sphere.

40. The method according to claim 38 wherein one of said one or more different shapes is an asymmetric changing ellipsoid.

41. The method according to claim 38 wherein one of said one or more different shapes is the actual shape of the cardiac chamber as determined by other precursor imaging and sizing methods, including x-ray, magnetic resonance imaging, ultrasound, surgery or other similar methods capable of determining dimensions of the target cardiac chamber.

42. The method according to claim 38 further including the additional steps of determining one or more cardiac performance parameters.

43. The method according to claim 42 wherein one of said one or more cardiac performance parameters is stroke volume, said stroke volume calculated by taking a difference between a maximum chamber volume and a minimum chamber volume on a beat-by-beat basis.

44. The method according to claim 43 wherein another one of said one or more cardiac performance parameters is cardiac output, said cardiac output calculated by multiplying said stroke volume by the heart rate.

45. The method according to claim 43 wherein another one of said one or more cardiac performance parameters is ejection fraction, said ejection fraction calculated by dividing said stroke volume by a maximum chamber volume.

46. A non-invasive system for determining dynamic physiologic and structural anatomic data from a subject comprising an ultrawideband radar system having a transmitting and receiving antenna for applying ultrawideband signals to a target area of a subject'"'"'s anatomy wherein said receiving antenna collects signal returns from said target area which are then delivered to a data processing and control unit having software and hardware used to process said signal returns to produce a value for cardiac stroke volume and changes in cardiac stroke volume supporting multiple diagnostic requirements.

47. The system according to claim 46 wherein said ultrawideband radar system comprises a transceiver having an impulse transmitter and a swept-range receiver wherein said impulse transmitter generates a series of ultrawideband pulses, said swept-range receiver captures resulting reflections across a target range of interest and a signal processor operates on said range-dependent reflections to extract desired data.

48. The system according to claim 47 wherein said target range of interest is a chest cavity, including at least one cardiac chamber.

49. The system according to claim 47 wherein said desired data is any of instantaneous cardiac chamber volume, stroke volume, cardiac output and ejection fraction.