Method and apparatus for determining the left-ventricular ejection time TLVE of a heart of a subject

• US 20030163058A1
• Filed: 10/09/2002
• Published: 08/28/2003
• Est. Priority Date: 10/11/2001
• Status: Active Grant

• Current Assignee: Osypka Medical GmbH
• Original Assignee: Osypka Medical GmbH
• Inventors: Bernstein, Donald P., Osypka, Markus J.
• Granted Patent: US 7,822,470 B2
• Time in Patent Office: Days
• US Class Current: 600/513
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• 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 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

In order to reliably determine the left-ventricular ejection time T_LVE of a heart of a subject, at least two different measuring methods are employed. This includes in any case the derivation of a first waveform related to thoracic electrical bioimpedance or bioadmittance. A second waveform can be determined by using pulse oximetry, Doppler velocimetry, measurement of arterial blood pressure and measurement of peripheral electrical bioimpedance or bioadmittance. Depending on signal quality, the results obtained by each method are weighted and then averaged. The weighted average for left-ventricular ejection time is used as an input variable for cardiovascular monitoring methods, which determine objective measurements of cardiovascular function and performance. Such measurements include, but are not limited to, left ventricular ejection fraction, stroke volume, cardiac output, systolic time ratio, and indices of ventricular contractility.

Claims

1. A method of determining the left-ventricular ejection time T_LVE of a heart of a subject, comprising:

deriving a first waveform including measuring a value selected from the group comprising thoracic electrical bioimpedance and thoracic electrical bioadmittance over time;

deriving at least a second waveform by using a method selected from the group comprising pulse oximetry, Doppler velocimetry, measurement of arterial blood pressure, measurement of peripheral electrical bioimpedance, and measurement of peripheral electrical bioadmittance; and

using said first waveform and at least said second waveform in order to determine T_LVE.

2. The method according to claim 1, wherein said second waveform is derived by using pulse oximetry.

3. The method according to claim 1, wherein said second waveform is derived by using pulse oximetry, and wherein said pulse oximetry measures the intensity of light absorbed by a finger of the subject, wherein light is emitted at one side of the finger and light is detected at the other side of the finger.

4. The method according to claim 3, wherein two wavelengths of light are utilized in pulse oximetry, the first wavelength being in the red band and the second wavelength being in the infrared band.

5. The method according to claim 1, wherein said second waveform is derived by using Doppler velocimetry.

6. The method according to claim 1, wherein said second waveform is derived by using esophageal Doppler velocimetry.

7. The method according to claim 5, wherein a Doppler velocimeter is applied to a radial artery of the subject.

8. The method according to claim 1, wherein said second waveform is derived by using pulse oximetry, and wherein a third waveform is derived by using esophageal Doppler velocimetry, and wherein said first, second, and third waveforms are used to determine T_LVE.

9. The method according to claim 6 or 8, wherein the deriving of said first waveform comprises placing at least two electrodes on a catheter and inserting said catheter into the esophagus of the subject, and wherein the esophageal Doppler velocimetry is performed by using a transducer placed on said same catheter.

10. The method according to claim 1, wherein said second waveform is derived by using pulse oximetry, and wherein a third waveform is derived by using one of the group comprising Doppler velocimetry at a radial artery of the subject, non-invasive measurement of blood pressure in a radial artery of the subject, and wherein said first, second, and third waveforms are used to determine T_LVE.

11. The method according to claim 1, wherein at least a third waveform is derived by using a method different from the method used to derive said first and second waveforms, and wherein said first, second, and third waveforms are used to determine T_LVE.

12. The method according to claim 1 or 11, wherein:

a) in a first step, all of said waveforms are independently used to determine T_LVE by applying predetermined criteria to define the opening point and the closure point of the aortic valve in said waveforms, and wherein

b) in a second step, the values of T_LVE obtained are averaged by using predetermined weights for the T_LVE values obtained from all of said waveforms.

13. The method according to claim 1 or 11, wherein:

a) predetermined criteria are used to independently define the opening point and the closure point of the aortic valves in all of said waveforms,

b) all of said waveforms are aligned synchronously with time,

c) the opening points defined in said waveforms are used to derive an averaged opening point by using predetermined criteria,

d) the closure points defined in said waveforms are used to derive an averaged closure point by using predetermined criteria, and wherein

e) T_LVE is determined by calculating the time interval starting with said averaged opening point and ending at said averaged closure point.

14. The method according to claim 1, wherein an expectation window for T_LVE is established prior to precisely determining T_LVE.

15. The method according to claim 14, wherein said expectation window is established on the basis of a regression equation for T_LVE in dependence on the heart rate HR.

16. A system for determining the left-ventricular ejection time T_LVE of a heart of a subject, comprising:

a first apparatus for measuring a value selected from the group comprising thoracic electrical bioimpedance and thoracic electrical bioadmittance over time; and

at least one second apparatus selected from the group comprising;

an apparatus for deriving plethysmogram data,

an apparatus for deriving signal data representing the velocity of blood in an artery in the vicinity of the esophagus of the subject,

an apparatus for deriving signal data representing the velocity of blood in radial artery of the subject,

a first apparatus for measuring data representing the blood pressure in an artery of the subject, said first apparatus for measuring data comprising a pressure sensor adapted to be non-invasively attached to the subject,

a second apparatus for measuring data representing the blood pressure in an artery of the subject, said second apparatus for measuring data comprising a pressure sensor adapted to be inserted into an artery of the subject,

an apparatus for measuring peripheral electrical bioimpedance, and

an apparatus for measuring peripheral electrical bioadmittance.

17. The system according to claim 16, further comprising:

a device coupled to said first apparatus for determining a value of T_LVE from the values measured by said first apparatus,

for each of said second apparatus selected from the group;

a device coupled to the respective second apparatus for determining a value of T_LVE from the data obtained by said apparatus, and

a device for averaging all determined values of T_LVE according to p redetermined weights.

18. The system according to claim 16, further comprising:

a device coupled to said first apparatus for defining the opening and the closure time of the aortic valve of the subject on the basis of the values measured by said first apparatus, and

for each of said second apparatus selected from the group;

a device coupled to the respective second apparatus for determining the opening and the closure time of the aortic valve of the subject on the basis of the data obtained by said second apparatus,

a device for deriving an averaged opening time of the aortic valve on the basis of all opening times defined by respective devices,

a device for deriving an averaged closure time of the aortic valve on the basis of all closure times defined by respective devices,

a device for calculating a time from said averaged opening time to said average closure time.

19. The system according to claim 16, further comprising at least one of the devices selected from the group of a display for displaying the value of T_LVE determined by said system, an output line for electronically outputting the value of T_LVE determined by said system, and a printer for printing out the value of T_LVE determined by said system.

20. The system according to claim 16, wherein said first apparatus comprises:

at least two electrodes;

an alternating current (AC) source;

a voltmeter; and

a processing unit for calculating said value.

21. The system according to claim 20, wherein said electrodes are adapted to attach to the thorax of the subject.

22. The system according to claim 20, wherein said electrodes are placed on a catheter adapted to be inserted in the esophagus of the subject.

23. The system according to claim 20, wherein

said second apparatus is an apparatus for deriving signal data representing the velocity of blood in an artery in the vicinity of the esophagus of the subject, said second apparatus comprising a transducer attached to a catheter, and wherein

said at least two electrodes of said first apparatus are also placed on said catheter.

24. A system for determining the left-ventricular ejection time T_LVE of a heart of a subject, comprising:

a) at least two electrodes,

an alternating current (AC) source, and

a voltmeter;

b) an emitter and a sensor for electromagnetic radiation, both being adapted to be attached to at least one of a fingertip and a toe of the subject; and

c) a processing apparatus comprising;

i) one of the group selected from an electrical bioimpedance analyzer and an electrical bioadmittance analyzer,

ii) a pulse oximetry processor, and

iii) a processing unit coupled to said analyzer and said processor.

25. A system for determining the left-ventricular ejection time T_LVE of a heart of a subject, comprising:

a) at least two electrodes,

an alternating current (AC) source, and

an voltmeter;

b) an ultrasound emitter, and

an ultrasound detector; and

c) a processing apparatus comprising;

i) one of the group selected from an electrical bioimpedance analyzer and an electrical bioadmittance analyzer,

ii) a Doppler velocimeter for controlling said ultrasound emitter and for obtaining signals from said ultrasound detector, and

iii) a processing unit coupled to said analyzer and said Doppler velocimeter.

26. The system according to claim 25, wherein said electrodes, said ultrasound emitter and said ultrasound detector are placed on a catheter.

27. The system according to claim 25 or 26, further comprising:

d) an emitter and a sensor for electromagnetic radiation, both being adapted to attach to at least one of a fingertip and a toe of said subject, and wherein said processing apparatus further comprises;

iv) a pulse oximetry processor, said processing unit being coupled to said processor.

28. A system for determining the left-ventricular ejection time T_LVE of a heart of a subject, comprising:

a) at least two electrodes,

an alternating current (AC) source, and

an voltmeter;

b) an emitter and a sensor for electromagnetic radiation including infrared;

c) a device applicable to a limb of said subject for obtaining data representing physical entities which are changing during the stroke of said heart; and

d) a processing apparatus comprising;

i) one of the group selected from an electrical bioimpedance analyzer and an electrical bioadmittance analyzer,

ii) a pulse oximetry processor,

iii) a processor for processing the data obtained by said device, and

iv) a processing unit coupled to said analyzers and said processors.

29. The system according to claim 28, wherein said device is selected from the group comprising:

an ultrasound transducer adapted to be attached to a wrist of said subject,

a pressure sensor adapted to be attached to a wrist of said subject, and

a pressure sensor adapted to be inserted in a peripheral artery of said subject.

30. An apparatus adapted to be inserted into the esophagus of a subject, comprising:

a catheter;

at least two electrodes placed onto said catheter, and

an ultrasound emitter and an ultrasound receiver placed onto said catheter.

31. The catheter according to claim 30, wherein a single transducer is used as said ultrasound emitter and receiver.