Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2003-01-28
2004-04-13
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S485000
Reexamination Certificate
active
06719704
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vascular-endothelial-cell-function evaluating apparatus that evaluates a function of vascular endothelial cells of a living subject.
2. Related Art Statement
Conventionally, the function of vascular endothelial cells of a living person is evaluated by imaging, using an ultrasound diagnostic device, a state in which blood vessels are dilated by administering a drug such as acetylcholine, or by pressing, using a cuff, a body portion of the person to stop a flow of blood in the body portion for several minutes and subsequently releasing the pressing of the cuff.
However, it is not recommended to administer any drugs in a living person. In addition, an ultrasound diagnostic device is expensive, and is not easy to use. Thus, the evaluation of vascular-endothelial-cell function is not practiced so widely.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a vascular-endothelial-cell-function evaluating apparatus that can easily evaluate the function of vascular endothelial cells of a living subject.
The Inventors have carried out extensive studies and found that if a body portion of a living subject is pressed using a cuff, the diameter of blood vessels is changed by the pressing of the cuff, and that as the diameter of blood vessels is changed, a reflected-wave component of a pulse wave obtained from the cuff or a distal body portion of the subject located on a distal side of the cuff, is also changed. The Inventors have additionally found that the degree of change of the reflected-wave component of pulse wave that is caused by the change of diameter of blood vessels, depends on the condition of vascular endothelial cells of the subject. Here, the reflected-wave component of pulse wave mainly influences a waveform of a second half of a heartbeat-synchronous pulse of pulse wave, the second half being subsequent to a peak point of the pulse. Thus, the Inventors have finally found that the degree of change of pulse-wave-second-half information representing a characteristic of the second half of pulse wave, caused by the change of diameter of blood vessels, depends on the condition of vascular endothelial cells of the subject. The present invention has been developed based on these findings.
The above object has been achieved by the present invention. According to the present invention, there is provided a vascular-endothelial-cell-function evaluating apparatus comprising a pressing device including a cuff that is adapted to be worn on a first portion of a living subject, and a cuff-pressure changing device that changes a pressure in the cuff so as to press the first portion of the subject in a pressing period; a pulse-wave detecting device that detects a pulse wave including a plurality of heartbeat-synchronous pulses, from the first portion of the subject, or a second portion of the subject located on a distal side of the first portion; and a pulse-wave-second-half-information obtaining device that obtains a plurality of sets of pulse-wave-second-half information that represent respective characteristics of respective second-half portions of respective heartbeat-synchronous pulses of the pulse wave that are detected by the pulse-wave detecting device at respective different times, the respective second-half portions of the respective heartbeat-synchronous pulses being respective portions of the respective pulses that are subsequent to respective peak points of the respective pulses, the pulse-wave-second-half-information obtaining device providing a time-wise change of the sets of pulse-wave-second-half information that is caused by the pressing of the pressing device.
Here, the pressing period in which the cuff-pressure changing device changes the pressure in the cuff to press the first portion of the subject may be a prescribed time duration or a time duration defined by a prescribed operation such as a blood-pressure-measurement-related pressure changing operation, described later.
According to the present invention, the pulse-wave-second-half-information obtaining device obtains the plurality of sets of pulse-wave-second-half information, and provides the time-wise change of the sets of pulse-wave-second-half information that is caused by the pressing of the pressing device. It is possible to evaluate, based on the time-wise change of the sets of pulse-wave-second-half information, the function of vascular endothelial cells of the subject. Therefore, it is not needed to use an ultrasound diagnostic device and accordingly it is easy to evaluate the function of vascular endothelial cells.
According to a preferred feature of the present invention, the pressing device presses, with the cuff, the first portion of the subject so as to stop a flow of blood in the first portion, and subsequently decreases the pressure of the cuff down to a pressure not higher than a mean blood pressure of the first portion, and the pulse-wave-second-half-information obtaining device obtains the sets of pulse-wave-second-half information in a waveform-deformation period in which the pressure of the cuff has already been decreased to the pressure not higher than the mean blood pressure of the first portion and respective waveforms of the respective heartbeat-synchronous pulses of the pulse wave are deformed yet as a result of the pressing of the pressing device. According to this feature, in the waveform-deformation period in which the pressure of the cuff has already been decreased to the pressure not higher than the mean blood pressure of the first portion, after the cuff stops the flow of blood in the first portion of the subject, and the respective waveforms of the respective heartbeat-synchronous pulses of the pulse wave are deformed yet by the pressing of the pressing device, the pulse-wave-second-half-information obtaining device time-wise obtains the sets of pulse-wave-second-half information based on the respective waveforms of the respective heartbeat-synchronous pulses of the pulse wave detected by the pulse-wave detecting device. If the cuff stops the flow of blood in the first portion, the diameter of blood vessels decreases because no blood flows in the second portion located on the distal side of the cuff. However, thereafter, when the pressure of the cuff is decreased down to the pressure not higher than the mean blood pressure of the first portion, the diameter of blood vessels increases and temporarily exceeds an initial diameter in order to quickly supply blood to the second portion. Since the pulse-wave-second-half-information obtaining device time-wise obtains the sets of pulse-wave-second-half information after the pressure of the cuff has been decreased down to the pressure not higher than the mean blood pressure of the first portion, it can provide a great time-wise change of the sets of pulse-wave-second-half information. Thus, it is particularly easy to evaluate the function of vascular endothelial cells of the subject.
According to another feature of the present invention, the cuff-pressure changing device of the pressing device includes a blood-flow stopping device for increasing the pressure of the cuff up to a pressure higher than a systolic blood pressure of the first portion of the subject, so as to stop a flow of blood in the first portion; a first pulse-wave-detection-pressure keeping device for keeping, before the blood-flow stopping device increases the pressure of the cuff, the pressure of the cuff at a pulse-wave detection pressure not higher than a mean blood pressure of the first portion, for a time duration corresponding to at least one heartbeat of the subject; and a second pulse-wave-detection-pressure keeping device for keeping, after the blood-flow stopping device increases the pressure of the cuff, the pressure of the cuff at a pulse-wave detection pressure not higher than a mean blood pressure of the first portion, for a time duration corresponding to at least one heartbeat of the subject, the pulse-wave detecting device detects a cuff
Narimatsu Kiyoyuki
Ogura Toshihiko
Tampo Akira
Colin Corporation
Oliff & Berridg,e PLC
Veniaminov Nikita R
Winakur Eric F.
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