Heart-function monitor apparatus

• US 6,334,849 B1
• Filed: 05/22/2000
• Issued: 01/01/2002
• Est. Priority Date: 05/25/1999
• Status: Expired due to Fees

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Colin Corporation (Fukuda Denshi Company Limited)
• Inventors: Sunagawa, Kenji
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US09/576,435
• Time in Patent Office: 589 Days
• Field of Search: 600/500, 600/490, 600/485, 600/526, 600/504, 600/561, 600/586, 600/508, 600/503
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• 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 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02208 using the Korotkoff method
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• 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 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence

Abstract

An apparatus for monitoring a function of the heart of a person, including a pre-ejection period measuring device which non-invasively measures a pre-ejection period, an ejection-period measuring device which non-invasively measures an ejection period, an aorta-pressure estimating device for estimating blood pressure values in the aorta, a telediastolic-aorta-pressure determining device for determining, based on the estimated aorta blood pressure values, a telediastolic blood pressure in the aorta at a telediastolic time of the heart, a telesystolic-aorta-pressure determining device for determining, based on the estimated aorta blood pressure values, a telesystolic blood pressure in the aorta at a telesystolic time of the heart, an stroke-volume measuring device which non-invasively measures a stroke volume of the left ventricle, and a telesystolic-elastance determining device for determining, based on the measured pre-ejection period, ejection period, and stroke volume and the determined aorta telediastolic and telesystolic blood pressure values, a telesystolic elastance of the left ventricle, according a predetermined relationship between (A) left-ventricle telesystolic elastance and (B) (b1) pre-ejection period, (b2) ejection period, (b3) aorta telediastolic blood pressure, (b4) aorta telesystolic blood pressure, and (b5) stroke volume.

Claims

1. An apparatus for monitoring a function of a heart of a living subject, comprising:

a pre-ejection period measuring device which non-invasively measures a pre-ejection period from a time when contraction of a cardiac muscle of a left ventricle of the heart starts, to a time when ejection of blood from the left ventricle starts;

an ejection-period measuring device which non-invasively measures an ejection period during which the blood is ejected from the left ventricle;

an aorta-pressure estimating means for estimating blood pressure values in an aorta of the subject;

a telediastolic-aorta-pressure determining means for determining, based on the aorta blood pressure values estimated by the aorta-pressure estimating means, a telediastolic blood pressure in the aorta at a telediastolic time of the heart;

for determining, based on the aorta blood pressure values estimated by the aorta-pressure estimating means, a telesystolic blood pressure in the aorta at a telesystolic time of the heart;

a stroke-volume measuring device which non-invasively measures a stroke volume that is a volume of blood ejected from the left ventricle of the heart by a one-time beat of the heart; and

a telesystolic-elastance determining means for determining, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, and the measured stroke volume, a telesystolic elastance of the left ventricle of the heart, according to a predetermined relationship between (A) left-ventricle telesystolic elastance and (B) (b1) pre-ejection period, (b2) ejection period, (b3) aorta telediastolic blood pressure, (b4) aorta telesystolic blood pressure, and (b5) stroke volume.

2. An apparatus according to claim 1, wherein the telesystolic-elastance determining means comprises means for determining, according to said predetermined relationship, the telesystolic elastance of the left ventricle of the heart, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, the measured stroke volume, and a predetermined telediastolic pressure in the left ventricle at the telediastolic time of the heart.

3. An apparatus according to claim 2, wherein said predetermined relationship is defined by a following expression:

4. An apparatus according to claim 3, further comprising an output-rate measuring device which non-invasively measures a volume of the left ventricle at the telediastolic time of the heart, and determines an output rate of the left ventricle of the heart by dividing the measured stroke volume by the measured left-ventricle telediastolic volume, wherein the telesystolic-elastance determining means determines, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, the measured stroke volume, the measured output rate, and the left-ventricle telediastolic pressure, a telesystolic elastance of the left ventricle of the heart, according a predetermined relationship between (A) left-ventricle telesystolic elastance and (B) (b1) pre-ejection period, (b2) ejection period, (b3) aorta telediastolic blood pressure, (b4) aorta telesystolic blood pressure, (b5) stroke volume, and (b6) output rate.

5. An apparatus according to claim 4, wherein the coefficient α

₀ of said expression is defined by a following expression;

6. An apparatus according to claim 4, wherein the coefficient α

₀ of said expression is defined by a following expression;

7. An apparatus according to claim 1, wherein the pre-ejection period measuring device comprises:

an electrocardiograph which includes a plurality of electrodes adapted to contact a body surface of the subject, and which detects, from the subject, an electrocardiogram waveform including a Q wave;

a heart-sound detecting device which is located in a body cavity of the subject, at a position in a vicinity of the heart of the subject, and which detects, from the subject, at least a first heart sound I; and

means for determining, as the pre-ejection period, a time period from a time when the Q wave of the electrocardiogram waveform is detected to a time when an end of the first heart sound I is detected.

8. An apparatus according to claim 1, wherein the ejection-period measuring device comprises:

a heart-sound detecting device which is worn on the subject, at a position in a vicinity of the heart of the subject, and which detects, from the subject, a first heart sound I and a second heart sound II; and

means for determining, as the ejection period, a time period from a time when an end of the first heart sound I is detected to a time when a start of the second heart sound II is detected.

9. An apparatus according to claim 1, wherein the telediastolic-aorta-pressure determining means comprises:

an electrocardiograph which includes a plurality of electrodes adapted to contact a body surface of the subject, and which detects, from the subject, an electrocardiogram waveform including a Q wave; and

means for determining, as the telediastolic aorta blood pressure, a blood pressure which is estimated by the aorta-pressure estimating means as an aorta blood pressure at a time when the Q wave of the electrocardiogram waveform is detected by the electrocardiograph.

10. An apparatus according to claim 1, wherein the telesystolic-aorta-pressure determining means comprises:

a heart-sound detecting device which is worn on the subject, at a position in a vicinity of the heart of the subject, and which detects at least a second heart sound II from the subject; and

mean s for determining, as the telesystolic aorta blood pressure, a blood pressure which is estimated by the aorta-pressure estimating means as an aorta blood pressure at a time when a start of the second heart sound II is detected by the heart-sound detecting device.

11. An apparatus according to claim 1, wherein the pre-ejection period measuring device non-invasively measures, each time the heart contracts and expands, a pre-ejection period from a time when the contraction of the cardiac muscle of the left ventricle of the heart starts, to a time when the ejection of the blood from the left ventricle starts;

the ejection period measuring device non-invasively measures, each time the heart contracts and expands, an ejection period during which the blood is ejected from the left ventricle starts;

the aorta-pressure estimating means estimates, each time the heart contracts and expands, blood pressure values in the aorta of the subject;

each time the heart contracts and expands, the telediastolic-aorta-pressure determining means determines, based on the estimated blood pressure values of the aorta, a telediastolic blood pressure in the aorta at a telediastolic time of the heart;

each time the heart contracts and expands, the telesystolic-aorta-pressure determining means determines, based on the estimated blood pressure values of the aorta, a telesystolic blood pressure in the aorta at a telesystolic time of the heart;

each time the heart contracts and expands, the stroke-volume measuring device measures a stroke volume of the left ventricle; and

each time the heart contracts and expands, the telesystolic elastance determining means determines, based on the measured pre-ejection period, the measured ejection period, the determined telediastolic aorta blood pressure, the determined telesystolic aorta blood pressure, and the measured stroke volume, a telesystolic elastance value of the left ventricle of the heart according to said predetermined relationship, and wherein the apparatus further comprises a display device which displays, along an axis indicative of time, the left-ventricle telesystolic elastance values which are successively determined by the telesystolic elastance determining means as the heart successively contracts and expands.

12. An apparatus according to claim 1, wherein the aorta-pressure estimating means comprises:

a blood-pressure measuring device which includes an inflatable cuff adapted to be wound around a body portion of the subject, and which measures at least one blood pressure of the subject when an air pressure in the cuff is changed;

a pulse-wave sensor which is adapted to be pressed against an artery of the subject via a skin tissue of the subject so as to flatten a portion of a wall of the artery, and which detects a pressure pulse wave transmitted thereto from the artery via the flattened wall portion of the artery and the skin tissue;

relationship determining means for determining a relationship between blood pressure and pressure-pulse-wave magnitude, based on at least one blood pressure measured by the blood-pressure measuring device and at least one magnitude of the pressure pulse wave detected by the pulse-wave sensor; and

means for calibrating, according to the determined relationship, instantaneous magnitudes of the pressure pulse wave detected by the pulse-wave sensor, and thereby providing a waveform representing the estimated aorta blood pressure values of the subject.

13. An apparatus for monitoring a function of a heart of a living subject, comprising:

a pre-ejection period measuring device which non-invasively measures a pre-ejection period from a time when contraction of a cardiac muscle of a left ventricle of the heart starts, to a time when ejection of blood from the left ventricle starts;

an ejection-period measuring device which non-invasively measures an ejection period during which the blood is ejected from the left ventricle;

an aorta-pressure estimating means for estimating blood pressure values in an aorta of the subject;

a telediastolic-aorta-pressure determining means for determining, based on the aorta blood pressure values estimated by the aorta-pressure estimating means, a telediastolic blood pressure in the aorta at a telediastolic time of the heart;

a telesystolic aorta-pressure determining means for determining, based on the aorta blood pressure values estimated by the aorta-pressure estimating means, a telesystolic blood pressure in the aorta at a telesystolic time of the heart;

a stroke-volume and output-rate measuring device which non-invasively measures a stroke volume that is a volume of blood ejected from the left ventricle of the heart, and an output rate that is a percentage of blood in the left ventricle of the heart ejected from the left ventricle of the heart, by a one-time beat of the heart; and

a telesystolic-elastance determining means for determining, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, the measured stroke volume and the measured output rate, a telesystolic elastance of the left ventricle of the heart, according to a predetermined relationship between (A) left-ventricle telesystolic elastance and (B) (b1) pre-ejection period, (b2) ejection period, (b3) aorta telediastolic blood pressure, (b4) aorta telesystolic blood pressure, (b5) stroke volume and (b6) output rate.

14. An apparatus according to claim 13, wherein the telesystolic-elastance determining means comprises means for determining, according to said predetermined relationship, the telesystolic elastance of the left ventricle of the heart, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, the measured stroke volume and output rate, and a predetermined telediastolic pressure in the left ventricle at the telediastolic time of the heart.

15. An apparatus according to claim 14, wherein said predetermined relationship is defined by a following expression:

16. An apparatus according to claim 15, wherein the stroke volume and output-rate measuring device non-invasively measures a volume of the left ventricle at the telediastolic time of the heart, and determines an output rate of the left ventricle of the heart by dividing the measured stroke volume by the measured left-ventricle telediastolic volume, wherein the telesystolic-elastance determining means determines, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, the measured stroke volume, the measure output rate, and the left-ventricle telediastolic pressure, a telesystolic elastance of the left ventricle of the heart, according to a predetermined relationship between (A) left-ventricle telesystolic elastance and (B) (b1) pre-ejection period, (b2) ejection period, (b3) aorta telediastolic blood pressure, (b4) aorta telesystolic blood pressure, (b5) stroke volume, and (b6) output rate.

17. An apparatus according to claim 16, wherein the coefficient α

₀ of said expression is defined by a following expression;

18. An apparatus according to claim 16, wherein the coefficient α

₀ of said expression is defined by a following expression;

19. An apparatus according to claim 13, wherein the pre-ejection period measuring device comprises:

an electrocardiograph which includes a plurality of electrodes adapted to contact a body surface of the subject, and which detects, from the subject, an electrocardiogram waveform including a Q wave;

a heart-sound detecting device which is located in a body cavity of the subject, at a position in a vicinity of the heart of the subject, and which detects, from the subject, at least a first heart sound I; and

means for determining, as the pre-ejection period, a time period from a time when the Q wave of the electrocardiogram waveform is detected to a time when an end of the first heart sound I is detected.

20. An apparatus according to claim 13, wherein the ejection-period measuring device comprises:

a heart-sound detecting device which is worn on the subject, at a position in a vicinity of the heart of the subject, and which detects, from the subject, a first heart sound I and a second heart sound II; and

means for determining, as the ejection period, a time period from a time when an end of the first heart sound I is detected to a time when a start of the second heart sound II is detected.

21. An apparatus according to claim 13, wherein the telediastolic-aorta-pressure determining means comprises:

an electrocardiograph which includes a plurality of electrodes adapted to contact a body surface of the subject, and which detects, from the subject, an electrocardiogram waveform including a Q wave; and

means for determining, as the telediastolic aorta blood pressure, a blood pressure which is estimated by the aorta-pressure estimating means as an aorta blood pressure at a time when the Q wave of the electrocardiogram waveform is detected by the electrocardiograph.

22. An apparatus according to claim 13, wherein the telesystolic-aorta-pressure determining means comprises:

a heart-sound detecting device which is worn on the subject, at a position in a vicinity of the heart of the subject, and which detects at least a second heart sound II from the subject; and

means for determining, as the telesystolic aorta blood pressure, a blood pressure which is estimated by the aorta-pressure estimating means as an aorta blood pressure at a time when a start of the second heart sound II is detected by the heart-sound detecting device.

23. An apparatus according to claim 13, wherein the pre-ejection period measuring device non-invasively measures, each time the heart contracts and expands, a pre-ejection period from a time when the contraction of the cardiac muscle of the left ventricle of the heart starts, to a time when the ejection of the blood from the left ventricle starts;

the ejection period measuring device non-invasively measures, each time the heart contracts and expands, an ejection period during which the blood is ejected from the left ventricle starts;

the aorta-pressure estimating means estimates, each time the heart contracts and expands, blood pressure values in the aorta of the subject;

each time the heart contracts and expands, the telediastolic-aorta-pressure determining means determines, based on the estimated blood pressure values of the aorta, a telediastolic blood pressure in the aorta at a telediastolic time of the heart;

each time the heart contracts and expands, the telesystolic-aorta-pressure determining means determines, based on the estimated blood pressure values of the aorta, a telesystolic blood pressure in the aorta at a telesystolic time of the heart;

each time the heart contracts and expands, the stroke-volume and output-rate measuring device measures a stroke volume and a stroke rate of the left ventricle; and

each time the heart contracts and expands, the telesystolic elastance determining means determines, based on the measured pre-ejection period, the measured ejection period, the determined telediastolic aorta blood pressure, the determined telesystolic aorta blood pressure, and the measured stroke volume and stroke rate, a telesystolic elastance value of the left ventricle of the heart according to said predetermined relationship, and wherein the apparatus further comprises a display device which displays, along an axis indicative of time, the left-ventricle telesystolic elastance values which are successively determined by the telesystolic elastance determining means as the heart successively contracts and expands.

24. An apparatus according to claim 13, wherein the aorta-pressure estimating means comprises:

a blood-pressure measuring device which includes an inflatable cuff adapted to be wound around a body portion of the subject, and which measures at least one blood pressure of the subject when an air pressure in the cuff is changed;

a pulse-wave sensor which is adapted to be pressed against an artery of the subject via a skin tissue of the subject so as to flatten a portion of a wall of the artery, and which detects a pressure pulse wave transmitted thereto from the artery via the flattened wall portion of the artery and the skin tissue;

relationship determining means for determining a relationship between blood pressure and pressure-pulse-wave magnitude, based on at least one blood pressure measured by the blood-pressure measuring device and at least one magnitude of the pressure pulse wave detected by the pulse-wave sensor; and

means for calibrating, according to the determined relationship, instantaneous magnitudes of the pressure pulse wave detected by the pulse-wave sensor, and thereby providing a waveform representing the estimated aorta blood pressure values of the subject.

25. A method for monitoring a function of a heart of a living subject, comprising the steps of:

non-invasively measuring a pre-ejection period from a time when contraction of a cardiac muscle of a left ventricle of the heart starts, to a time when ejection of blood from the left ventricle starts with a pre-ejection period measuring device;

non-invasively measuring an ejection period during which the blood is ejected from the left ventricle with an ejection-period measuring device;

estimating blood pressure values in an aorta of the subject with an aorta-pressure estimating means;

determining, based on the aorta blood pressure values estimated by the aorta-pressure estimating means, a telediastolic blood pressure in the aorta at a telediastolic time of the heart with a telediastolic-aorta-pressure determining means;

determining, based on the aorta blood pressure values estimated by the aorta-pressure estimating means, a telesystolic blood pressure in the aorta at a telesystolic time of the heart with a telesystolic-aorta-pressure determining means;

non-invasively measuring a stroke volume that is a volume of blood ejected from the left ventricle of the heart, and an output rate that is a percentage of blood in the left ventricle of the heart ejected from the left ventricle of the heart, by a one-time beat of the heart with a stroke-volume and output-rate measuring device; and

determining, based on the measured pre-ejection period, the measured ejection period, the determined aorta telediastolic blood pressure, the determined aorta telesystolic blood pressure, the measured stroke volume and the measured output rate, a telesystolic elastance of the left ventricle of the heart, according to a predetermined relationship between (A) left-ventricle telesystolic elastance and (B) (b1) pre-ejection period, (b2) ejection period, (b3) aorta telediastolic blood pressure, (b4) aorta telesystolic blood pressure, (b5) stroke volume and (b6) output rate with a telesystolic-elastance determining means.