Heart-function monitor apparatus

• US 6,254,544 B1
• Filed: 05/22/2000
• Issued: 07/03/2001
• 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: Hayashi, Kazuko
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): Mallari, Patricia C.
• Application Number:
  US09/575,822
• Time in Patent Office: 407 Days
• Field of Search: 600/500, 600/490, 600/485, 600/526, 600/504, 600/561, 600/586
• US Class Current: 600/500
• 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 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• 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 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

An apparatus for monitoring a function of a 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 a blood pressure in an aorta of the subject, a telediastolic-aorta-pressure determining device for determining, based on an aorta blood pressure estimated by the aorta-pressure estimating device, a telediastolic blood pressure in the aorta at a telediastolic time of the heart, a telesystolic-aorta-pressure determining device for determining, based on an aorta blood pressure estimated by the aorta-pressure estimating device, a telesystolic blood pressure in the aorta at a telesystolic time of the heart, and a cardiac-mechanical-efficiency determining device for determining, based on the measured pre-ejection period, the measured ejection period, the determined telediastolic aorta blood pressure, and the determined telesystolic aorta blood pressure, a cardiac mechanical efficiency of the person according a predetermined relationship between (A) cardiac mechanical efficiency and (B) (b1) pre-ejection period, (b2) ejection period, (b3) telediastolic aorta blood pressure, and (b4) telesystolic aorta blood pressure.

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;

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; and

a cardiac-mechanical-efficiency determining means for determining, based on the measured pre-ejection period, the measured ejection period, the determined telediastolic aorta blood pressure, and the determined telesystolic aorta blood pressure, a cardiac mechanical efficiency of the subject according a predetermined relationship between (A) cardiac mechanical efficiency and (B) (b1) pre-ejection period, (b2) ejection period, (b3) telediastolic aorta blood pressure and (b4) telesystolic aorta blood pressure.

2. An apparatus according to claim 1, wherein the predetermined relationship is defined by a following expression:

3. An apparatus according to claim 2, wherein the coefficient k of said expression is a variable expressed as a function of at least one of the cardiac mechanical efficiency and a ratio of the ejection period to the pre-ejection period.

4. An apparatus according to claim 2, wherein the coefficient k of said expression is a variable expressed as a function of the cardiac mechanical efficiency and a ratio of the ejection period to the pre-ejection period.

5. An apparatus according to claim 4, wherein the coefficient k of said expression is defined by a following expression:

6. 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, a first heart sound I and a second heart sound II; and

means for determining, as the pre-ejection period, a first 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.

7. An apparatus according to claim 6, wherein the ejection-period measuring device comprises means for determining a second time period from the time when the Q wave of the electrocardiogram waveform is detected to a time when a start of the second heart sound II is detected, and determining, as the ejection period, a third time period obtained by subtracting the first time period from the second time period.

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 ejection-period measuring device comprises means for determining, as the ejection period, a time period from a time of occurrence of a minimum point of a waveform representing the aorta blood pressure estimated by the aorta-blood-pressure estimating means to a time of occurrence of a notch of the waveform, the notch occurring at a time when an aortic valve of the heart is closed.

10. 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.

11. An apparatus according to claim 1, wherein the telesystolic-aorta-pressure determining means comprises means for determining, as the telesystolic aorta blood pressure, a blood pressure which is estimated by the aorta-pressure estimating means as an aorta mean blood pressure.

12. An apparatus according to claim 1, wherein the telesystolic-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 T wave; 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 an end of the T wave of the electrocardiogram waveform is detected by the electrocardiograph.

13. 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

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.

14. 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; and

, each time the heart contracts and expands, the cardiac-mechanical-efficiency determining means determines, based on the measured pre-ejection period, the measured ejection period, the determined telediastolic aorta blood pressure, and the determined telesystolic aorta blood pressure, a cardiac mechanical efficiency value of the subject according to the predetermined relationship between (A) cardiac mechanical efficiency and (B) (b1) pre-ejection period, (b2) ejection period, (b3) telediastolic aorta blood pressure and (b4) telesystolic aorta blood pressure, and wherein the apparatus further comprises a display device which displays, along an axis indicative of time, the cardiac mechanical efficiency values which are successively determined by the cardiac-mechanical-efficiency determining means as the heart successively contracts and expands.

15. 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.