Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2003-05-19
2004-11-09
Nasser, Robert L. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S485000, C600S490000
Reexamination Certificate
active
06814705
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an arteriosclerosis-degree evaluating apparatus for evaluating a degree of arteriosclerosis of a living subject.
2. Related Art Statement
As examples of a method of evaluating a degree of arteriosclerosis of a living subject, there are known an ultrasonic echo method in which the degree of arteriosclerosis is evaluated directly from an image of a blood vessel of the subject taken using an ultrasonic wave, and a method in which the degree of arteriosclerosis is evaluated indirectly from a measured pulse-wave propagation velocity PWV at which a pulse wave propagates in the subject.
In general, the pulse-wave propagation velocity PWV is measured in the following manner: Two sensors are worn on two body portions of the subject for detecting heartbeat-synchronous signals respectively from the two body portions. A pulse-wave propagation time DT is determined as a time difference between a time of detection of a prescribed portion of one of the two heartbeat-synchronous signals and a time of detection of a corresponding prescribed portion of the other of the two heartbeat-synchronous signals. Further, a pulse-wave propagation distance is determined as a distance between the two body portions on which the two sensors are respectively worn. The pulse-wave propagation velocity PWV is obtained by dividing the pulse-wave propagation distance by the pulse-wave propagation time DT. JP-A-2001-190506 discloses one example of an arteriosclerosis-degree evaluating apparatus wherein a pulse-wave propagation velocity PWV is determined for evaluating a degree of arteriosclerosis. Described in detail, the disclosed apparatus comprises a heart-sound microphone adapted to be worn on a chest of a living subject and a pressure pulse wave sensor adapted to be worn on a neck portion of the subject. In the disclosed apparatus, the pulse-wave propagation velocity PWV is determined based on a time difference between a time of detection of a start point of a second heart sound II and a time of detection of a notch point of a heartbeat-synchronous pulse of a pulse wave detected from a carotid artery, and a prescribed distance between the two body portions on which the heart-sound microphone and the pressure pulse wave sensor are respectively worn.
Since arteriosclerosis induces various kinds of diseases such as cerebrovascular disease and coronary disease, it is desirable that degree of arteriosclerosis be evaluated daily. However, an ultrasonic diagnosing apparatus used in the ultrasonic echo method is very expensive. For obtaining a pulse-wave propagation velocity, two sensors for respectively detecting two heartbeat-synchronous signals need to be appropriately worn on respective two body portions, for detecting pulses each having an accurate waveform with substantially no noise. Thus, the pulse-wave propagation velocity cannot be easily measured, and a certain degree of skill is needed to measure the velocity.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an arteriosclerosis-degree evaluating apparatus capable of easily evaluating a degree of arteriosclerosis of a living subject.
The above-indicated object of the present invention has been achieved by the present invention. According to the present invention, there is provided an apparatus for evaluating a degree of arteriosclerosis of a living subject, comprising: a pulse-wave detecting device adapted to be worn on a first portion of the living subject; a pressing device adapted to be worn on a second portion of the subject located on a distal side of the first portion, for pressing the second portion so as to restrict a flow of blood at the second portion; and an arteriosclerosis-related information obtaining means for obtaining arteriosclerosis-related information used for evaluating the degree of arteriosclerosis of the subject, based on a peak point of an incident-wave component, and a peak point of a reflected-wave component, of a pulse of a pulse wave that is detected by the pulse-wave detecting device in a state in which the flow of blood is restricted by the pressing device.
In the present arteriosclerosis-degree evaluating apparatus, when the flow of blood is restricted by the pressing device at the second portion of the subject on which the pressing device is worn, a reflected wave is generated at that second portion. Accordingly, the pulse wave detected by the pulse-wave detecting device worn on the first portion of the subject that is located on the proximal side of the pressing device is a composite wave consisting of an incident wave that represents an increase of a pressure in the artery that is caused by ejection of blood from the left ventricle of the heart of the subject, and the reflected wave generated at the second portion on which the pressing device is worn. The magnitude and the velocity of the reflected wave increase with an increase of the hardness of the artery. Accordingly, the location and the magnitude of a peak point of the reflected-wave component of the pulse vary relative to those of a peak point of the incident-wave component of the pulse, depending upon the degree of arteriosclerosis. Therefore, the present apparatus is capable of evaluating the degree of arteriosclerosis of the subject, based on the arteriosclerosis-related information that is obtained, by the arteriosclerosis-related information obtaining means, on the basis of the respective peak points of the incident-wave component, and the reflected-wave component, of the pulse. In the present apparatus, the single pulse-wave detecting device and the single pressing device are worn on the subject for evaluating the degree of arteriosclerosis of the subject, without using an expensive apparatus. Further, the present apparatus is capable of evaluating the degree of arteriosclerosis more easily than the conventional arrangement wherein the two detecting devices for respectively detecting the two heartbeat-synchronous signals are worn on the respective two body portions of the subject.
The arteriosclerosis-related information obtaining means preferably obtains, as the arteriosclerosis-related information, at least one of: (a) a time difference between a time of occurrence of the peak point of the incident-wave component of the pulse and a time of occurrence of the peak point of the reflected-wave component of the pulse; (b) a difference between a magnitude of the pulse at the time of occurrence of the peak point of the incident-wave component thereof and a magnitude of the pulse at the time of occurrence of the peak point of the reflected-wave component thereof; (c) a ratio between a magnitude of the pulse at the time of occurrence of the peak point of the reflected-wave component thereof, and a magnitude of the pulse at the time of occurrence of the peak point of the incident-wave component thereof; (d) a ratio of the difference between the magnitude of the pulse at the time of occurrence of the peak point of the incident-wave component thereof and the magnitude of the pulse at the time of occurrence of the peak point of the reflected-wave component thereof, to a pulse pressure of the pulse, and (e) a ratio of the ratio between the magnitude of the pulse at the time of occurrence of the peak point of the incident-wave component thereof and the magnitude of the pulse at the time of occurrence of the peak point of the reflected-wave component thereof, to the pulse pressure of the pulse.
In one preferred form of the present invention, the pulse-wave detecting device comprises a pressing bag adapted to be wound around the first portion of the subject, and the apparatus further comprises: a pressure changing means for changing a pressure in the pressing bag; and a blood-pressure determining means for determining a blood pressure value of the subject based on a signal which is obtained from the pressing bag when the pressure in the pressing bag is changed by the pressure changing means. According to this arrangement, the apparatus obtains, in add
Colin Medical Technology Corporation
Nasser Robert L.
Oliff & Berridg,e PLC
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