Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2002-07-15
2004-05-11
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S491000, C600S500000
Reexamination Certificate
active
06733460
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an arteriosclerosis diagnosing apparatus for diagnosing arteriosclerosis or arteriosclerotic lesion, in particular, atherosclerosis.
2. Related Art Statement
There are known three sorts of arteriosclerosis; atherosclerosis is atheromatous sclerosis of endothelium of large or medium arteries, mediosclerosis is calcification of media of arteries, and arteriolosclerosis is sclerosis of small arteries.
Meanwhile, pulse-wave-propagation-velocity-related information that is related to a velocity at which a pulse wave propagates between two regions of a living subject, e.g., pulse-wave propagation velocity itself or pulse-wave propagation time, may be measured to diagnose whether the subject has atherosclerosis or not, or what degree of atherosclerosis the subject has. If a pulse-wave propagation velocity as a sort of pulse-wave-propagation-velocity-related information is measured from an atherosclerotic region of the subject, the measured velocity is higher than a normal velocity, if a degree of the atherosclerosis is low; and the measured velocity is lower than the normal velocity, if the degree of atherosclerosis is medium or high. Thus, the pulse-wave-propagation-velocity-related information can be used to diagnose whether the subject has atherosclerosis, or what degree of atherosclerosis the subject has.
The reason why a measured pulse-wave propagation velocity is higher than a normal velocity if a degree of atherosclerosis is low and the measured velocity is lower than the normal velocity if the degree of atherosclerosis is medium or high, is as follows: As atherosclerosis that is also called arteriostenosis advances, the inner diameters of arteries decrease. Since blood pressure lowers downstream of the arteriostenotic region, pulse-wave propagation velocity that changes with the blood pressure also lowers. Meanwhile, since mediosclerosis is calcification of media, the pulse-wave propagation velocity increases as the mediosclerosis advances. Generally, the mediosclerosis advances with the atherosclerosis. In the case where the degree of atherosclerosis is low, the influence of mediosclerosis is stronger than that of the atherosclerosis and accordingly the pulse-wave propagation velocity is higher than the normal velocity. However, in the case where the degree of atherosclerosis is medium or high, the influence of atherosclerosis is stronger than that of the mediosclerosis and accordingly the pulse-wave propagation velocity is lower than the normal velocity.
Pulse-wave propagation velocity has the above-described relationship with atherosclerosis and mediosclerosis. Since, however, the present invention relates to an apparatus for diagnosing atherosclerosis or arteriostenosis, the following description employs such a definition that arteriosclerosis means atherosclerosis, unless it otherwise specifies.
There is known an inferior-and-superior-limb blood-pressure-index measuring apparatus as a sort of arteriosclerosis diagnosing apparatus. This apparatus is disclosed in, e.g., Japanese Patent No. 3,140,007 or its corresponding U.S. Pat. No. 6,355,000. The inferior-and-superior-limb blood-pressure-index measuring apparatus includes two cuffs that are adapted to be worn on an inferior limb and a superior limb of a living subject, calculates, as an inferior-and-superior-limb blood-pressure-index, a ratio of one of a superior-limb blood pressure and an inferior-limb blood pressure to the other, and diagnoses arteriosclerosis based on the thus calculated inferior-and-superior-limb blood-pressure-index. If this apparatus is so modified as to be able to obtain pulse-wave-propagation-velocity-related information so as to assure the reliability of inferior-and-superior-limb blood-pressure-index, then the apparatus would be able to more accurately diagnose arteriosclerosis. If the two cuffs employed to measure the superior-limb blood pressure and the inferior-limb blood pressure are used to detect respective pulse waves from the superior limb and the inferior limb, the thus detected two pulse waves would be able to be used to determine a pulse-wave propagation time. Thus, the pulse-wave propagation time as another sort of pulse-wave-propagation-velocity-related information would be able to be obtained without needing to employing any additional sensors.
In many cases, arteriosclerosis occurs to inferior limbs only. However, in some cases, arteriosclerosis occurs to superior limbs as well. A pulse-wave propagation time measured from a superior limb and an inferior limb means a difference between a time of propagation of a pulse wave from the heart to the superior limb and a time of propagation of the pulse wave from the heart to the inferior limb. Therefore, in those cases, even if the inferior limb has arteriosclerosis and accordingly a time of propagation of pulse wave from the heart to the inferior limb increases, a pulse-wave propagation time measured from the superior limb and the inferior limb, or a pulse-wave propagation velocity determined based on the measured propagation time falls in a normal range, if the superior limb has arteriosclerosis and accordingly a time of propagation of pulse wave from the heart to the superior limb increases. Thus, in the above-indicated cases, the pulse-wave-propagation-velocity-related information obtained from the superior and inferior limbs cannot be used to diagnose arteriosclerosis with high accuracy.
Meanwhile, there are some cases where noise produced by a physical motion of a living subject is mixed with pulse waves and accordingly respective reference points of those pulse waves that are to be used to obtain pulse-wave propagation-velocity-related information cannot be accurately detected. In those cases, the pulse-wave-propagation-velocity-related information cannot be obtained with accuracy. In addition, if arrhythmia occurs to a living subject, respective reference points of two pulse waves to be used to obtain pulse-wave propagation-velocity-related information may not be accurately detected, and accordingly the pulse-wave-propagation-velocity-related information may not be obtained with accuracy. If pulse-wave-propagation-velocity-related information cannot be obtained with accuracy, then arteriosclerotic legion cannot be diagnosed with accuracy.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an arteriosclerosis diagnosing apparatus for diagnosing arteriosclerosis or arteriosclerotic lesion with high accuracy.
The above object has been achieved by the present invention. According to a first aspect of the present invention, there is provided an apparatus for diagnosing arteriosclerosis of a living subject, comprising an inflatable cuff which is adapted to be wound around a first portion of the subject to press said first portion with a pressing pressure; a pulse-wave detecting device which detects a pulse wave that is produced from an artery of said first portion of the subject pressed by the cuff with the pressing pressure and is transmitted to the cuff; and an arteriosclerosis judging means for judging, based on a change of the pulse wave caused by a change of the pressing pressure of the cuff, whether there is an arteriosclerotic lesion in a second portion of the subject that is located upstream of said first portion in a direction in which blood flows in the artery.
If the subject has arteriosclerosis in the second portion located upstream of the first portion around which the cuff is wound, the sharpness of shape of the pulse wave detected from the first portion by the pulse-wave detecting device significantly decreases at a lower pressing pressure of the cuff than a pressing pressure at which the sharpness of shape of a pulse wave detected from a first portion located downstream of a second portion free of arteriosclerosis significantly decreases. Therefore, the arteriosclerosis judging means can judge, based on the change of the pulse wave caused by the change of the pressing pressure of the cuff, whether
Colin Medical Technology Corporation
Hindenburg Max F.
Natnithithadha Navin
Oliff & Berridg,e PLC
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