Source: https://patents.google.com/patent/US20120179053A1/en
Timestamp: 2020-03-28 09:07:55
Document Index: 384012720

Matched Legal Cases: ['art 90', 'art 90', 'art 31', 'art 34', 'art 90', 'art 31', 'art 34', 'art 34', 'art 33']

US20120179053A1 - Apparatus for measuring a propagation velocity of a blood pressure wave - Google Patents
Apparatus for measuring a propagation velocity of a blood pressure wave Download PDF
US20120179053A1
US20120179053A1 US13/388,098 US201013388098A US2012179053A1 US 20120179053 A1 US20120179053 A1 US 20120179053A1 US 201013388098 A US201013388098 A US 201013388098A US 2012179053 A1 US2012179053 A1 US 2012179053A1
US13/388,098
CNR DIPARTIMENTO DI MEDICINA
2009-07-31 Priority to ITPI2009A000099 priority Critical
2009-07-31 Priority to ITPI20090099 priority patent/ITPI20090099A1/en
2010-08-02 Application filed by Fondazione Toscana Gabriele Monasterio, CNR DIPARTIMENTO DI MEDICINA filed Critical Fondazione Toscana Gabriele Monasterio
2010-08-02 Priority to PCT/IB2010/001901 priority patent/WO2011039580A2/en
2012-03-28 Assigned to CNR-DIPARTIMENTO DI MEDICINA, FONDAZIONE TOSCANA GABRIELE MONASTERIO reassignment CNR-DIPARTIMENTO DI MEDICINA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BIANCHINI, ELISABETTA, FAITA, FRANCESCO, GEMIGNANI, VINCENZO
2012-07-12 Publication of US20120179053A1 publication Critical patent/US20120179053A1/en
230000000747 cardiac Effects 0 claims abstract description 11
210000001715 Carotid Arteries Anatomy 0 claims description 17
210000001765 Aortic Valve Anatomy 0 claims description 11
An apparatus for measuring the propagation velocity of a pressure wave comprises a first sensor of cutaneous vibration to measure a vibration generated in a first application point, creating a corresponding first signal, and a second sensor of cutaneous vibrations to measure a local cutaneous vibration generated in second point of an arterial vessel, creating a corresponding second signal caused by the deformation of the vessel responsive to the progression of the pressure wave in the vessel. A control unit detects on the first and second signal respectively a first instant time T1 and a second instant time T2 corresponding to a same event of a cardiac cycle. On the basis of T1 and T2 a transit time PTT (Pulse Transit Time) is calculated of the pressure wave and then the propagation velocity is measured of the pressure wave as the ratio between the length of the path arterial.
The present invention relates to an apparatus for measuring the propagation velocity of a pressure wave in the central arterial system, by detecting signals of the cutaneous vibrations generated by the heart and signals of the cutaneous vibrations generated by the movement of the blood in an artery.
As well known, increasing the stiffness of blood vessels is a new and early index of increased cardiovascular risk. Different techniques exist for determining the arterial stiffness at systemic, regional and local levels. In particular, the regional arterial stiffness, i.e. the stiffness measurement in a determined portion of an artery, can be evaluated by measurement of the propagation velocity of the pressure wave also called PWV “Pulse Wave Velocity”, considered as a technique of reference in this field.
Other techniques provide, instead, the use of mechanical-transducers as in Asmar R, Benetos A, Topouchian J, Laurent P, Pannier B, Brisac A M, Target R, Levy B, “Assessment of the arterial distensibility by automatic pulse wave velocity measurement. Validation and clinical application studies” Hypertension 1995;26:485-490; or of tonometry, such as in Karamanoglu M, Gallagher D E, Avolio A P, O'Rourke MF—“Pressure wave propagation in to multibranched model of the human upper limb”—Am J Physiol 1995;269:H1363-H1369.
This way, it is possible to apply the second sensor for a long time on the patient's skin, at the application point of the sensor near the arterial vessel, without any discomfort for the patient, and measuring continuously the second cutaneous vibration signal. The propagation velocity of said pressure wave, i.e. the PWV, is then calculated continuously, and a chart can be produced during diagnostic examinations such as, for example, a stress test.
With reference to FIG. 1, a diagrammatical simplified view is shown of an apparatus 100/100′, according to the invention, for measuring the propagation velocity of a pressure wave. In particular, apparatus 100 comprises a first sensor of cutaneous vibrations 1 mounted in a first application point, in particular according to a first configuration, mounted at the heart, in order to measure a vibration generated by heartbeat 90, creating a corresponding first cutaneous vibration signal 10, and a second sensor 2, which is adapted to measure a local cutaneous vibration generated in a predetermined point of an arterial vessel 4, creating a corresponding second cutaneous vibration signal 20. More precisely, second sensor 2 detects the vibration caused by the deformation of vessel 4 responsive to the progression of the pressure wave. This way, it is possible to apply second sensor 2 for a long time on the patient's skin, at the application point of the sensor near arterial vessel 4, without any discomfort for the patient 30, and measuring continuously the second cutaneous vibration signal 20. The propagation velocity of the pressure wave, i.e. the PWV, is then calculated continuously, and a chart can be produced during diagnostic examinations such as, for example, stress tests. Furthermore, an instantaneous value of the PWV has a precision higher than that obtainable with known systems.
In particular, signal 10 of the vibrations of heart 90 has two peaks, the first at the beginning of the blood expulsion phase, at opening of aortic valve 31 b, and the second at the end of the blood expulsion phase, i.e. at closing aortic valve 31 a. These two peaks, if recorded in an audio band, correspond to first tone S1 and to second tone S2 of the phonocardiogram. In our case such peaks are referred to as first tone S1 and second tone S2, even if the considered signal has a band that is extended even outside the audio band, considering a cutaneous vibration signal characterised by a band extended towards below starting from the frequency zero.
In the same way, also signal 20 of the vibrations of arterial vessel 4 has two peaks; a first peak, referred to as C1, at the trough of wave 34 b of the carotid artery diameter, and a second peak, referred to as C2, at the “Dicrotic Notch” 34 a always of the carotid artery diameter. It is noted that such peaks are not obtained by the propagation along vessel 4 of sounds S1 and S2, but they are vibrations determined by the local deformation of the vessel same, which causes a corresponding cutaneous vibration.
Always as shown in FIG. 3, for determining the delay time PTT between the occurrence of a predetermined event of the cardiac cycle with respect to heart 90 and with respect to the distal point of vessel 4, namely in this case the point at sternum 6, it is necessary then to determine first time instant T1 that corresponds, for example, to closure of aortic valve 31 a, as shown in chart 31, and second time instant T2 that corresponds to the so-called “Dicrotic Notch” 34 a of the waveform of the diameter, shown by chart 34.
Alternatively, first time instant T1′ corresponds to opening aortic valve 31 b whereas second time instant T2′ corresponds to beginning a quick increase of the diameter, i.e. the wave trough 34 b. Such quick increase of diameter is due to arrival of the pulse pressure.
In the first case, the transit time PTT of the pressure wave, calculated by the analysis of the two generated signals of vibration 10/20, the former generated by the vibrations of heart 90 and the latter by the vibrations due to local deformation of the artery, in this case the carotid artery 4, is the difference between the instant of closure of aortic valve 31 a defined on the heartbeat signal, chart 31, and the instant of the “Dicrotic Notch” 34 a of the diameter defined on the vessel vibration signal, chart 34, since this “Dicrotic Notch” is just the occurrence of closing the aortic valve.
This way, with respect to the prior art, the present invention is different on how the occurrence of the cardiac event is determined with respect to arterial vessel 4. The principle is based on the fact that the pressure of the blood present into an arterial vessel generates locally a deformation of the vessel that causes a quick variation of diameter, which generates at a short distance a corresponding cutaneous vibration, as shown by chart 34. The waveform of the diameter can be assimilated to the waveform of the pressure, chart 33; these two chart are in phase with each other. It follows that the remarkable points of the waveform of the pressure, i.e. the trough of wave and the “dicrotic notch” 34 a are present at a same time instant in both waveforms, as shown in FIG. 3. The movement of the vessel that follows the variation of diameter generates in turn of the vibrations that are measurable with the sensor of cutaneous vibrations 2, which is located on the patient's skin, near the vessel same. By the analysis of this signal as above described, it is therefore possible to determine the time instants corresponding to the remarkable points of the waveform of the diameter T2 and T2′, i.e. the remarkable points of the pressure waveform.
1. An apparatus for measuring the propagation velocity of a pressure wave in a cardiovascular system, in particular a pressure wave arterial system, said apparatus comprising:
a program means for calculating the propagation velocity of said pressure wave responsive to said distance between said first and said second application points and to said first and second cutaneous vibration signals,
wherein said first and second sensors of cutaneous vibrations are adapted to measure vibrations set between 1 Hz and 20 KHz, in particular between 5 Hz and 80 Hz.
2. An apparatus, according to claim 1, wherein said first sensor is adapted to be arranged in a first application point of the central arterial system and that is located at the heart, in order to measure the cutaneous vibration generated by the heartbeat, whereas said second sensor is adapted to be arranged at a second application point which is at an arterial vessel at a distance from the heart, in order to measure the vibration caused by the deformation of the vessel responsive to the movement of said pressure wave.
3. An apparatus, according to claim 1, wherein said first sensor is adapted to be arranged in a first application point of the central arterial system and that is located at an arterial vessel at a distance from the heart, whereas said second sensor is adapted to be arranged at a second application point which is at the same arterial vessel at a predetermined distance from said first point, in order to measure a local cutaneous vibration by the deformation of the vessel in each of said points located on said same arterial vessel.
4. An apparatus, according to claim 1, wherein said program means is adapted to determine:
on said second cutaneous vibration signal a second instant time corresponding to the occurrence of the same event of the cardiac cycle as a local deformation of said arterial vessel;
said propagation velocity of said pressure wave as the ratio between the distance between the heart and the application point of said second sensor and said transit time.
5. An apparatus, according to claim 1, wherein said first and second sensors are selected from the group comprised of: an accelerometer, a microphone, or an inertial sensor.
6. An apparatus, according to claim 1, wherein said first and second sensors of cutaneous vibrations are applied by means of sticking plasters or other adhesive means, in order to provide a light contact with the skin of the patient at said first and second application points.
7. An apparatus, according to claim 1, wherein said apparatus comprises acquisition means of an electrocardiographic signal, said electrocardiographic signal being used as synchronism time for determining said first and second instant times.
8. An apparatus, according to claim 1, wherein said first sensor for acquisition of the signal of the cutaneous vibrations generated by the heart is adapted to be located on the sternum whereas said second sensor for acquisition of the signal of the cutaneous vibrations generated by said arterial vessel is adapted to be located on the neck of the patient, in particular at the carotid artery.
9. An apparatus, according to claim 1, wherein said first instant time corresponds to closing the aortic valve whereas said second instant time corresponds to the “Dicrotic Notch” of the waveform of the vessel diameter vibration.
10. An apparatus, according to claim 1, wherein said first instant time corresponds to opening the aortic valve whereas said second instant time corresponds to start of a quick increase of the diameter, i.e. the wave trough.
11. An apparatus, according to claim 1, wherein said program means is adapted to cause:
in basal conditions delay time T0 between a tone of said first signal and the corresponding tone of said second signal;
in post-basal conditions delay time T between a tone of said first signal and the corresponding tone of said second signal;
variation of the propagation velocity of said pressure wave as the ratio between said distance of the arterial path comprised between the heart and the application point of said second sensor, and said variation of the transit time ΔT of the pressure wave.
US13/388,098 2009-07-31 2010-08-02 Apparatus for measuring a propagation velocity of a blood pressure wave Abandoned US20120179053A1 (en)
ITPI2009A000099 2009-07-31
ITPI20090099 ITPI20090099A1 (en) 2009-07-31 2009-07-31 Apparatus for the measurement of the pressure wave propagation velocity in the arterial system
PCT/IB2010/001901 WO2011039580A2 (en) 2009-07-31 2010-08-02 Apparatus for measuring a propagation velocity of a blood pressure wave
US20120179053A1 true US20120179053A1 (en) 2012-07-12
ID=41668378
US13/388,098 Abandoned US20120179053A1 (en) 2009-07-31 2010-08-02 Apparatus for measuring a propagation velocity of a blood pressure wave
US (1) US20120179053A1 (en)
EP (1) EP2459060A2 (en)
IT (1) ITPI20090099A1 (en)
WO (1) WO2011039580A2 (en)
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2010-08-02 WO PCT/IB2010/001901 patent/WO2011039580A2/en active Application Filing
2010-08-02 US US13/388,098 patent/US20120179053A1/en not_active Abandoned
2010-08-02 EP EP20100809030 patent/EP2459060A2/en not_active Withdrawn
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Owner name: FONDAZIONE TOSCANA GABRIELE MONASTERIO, ITALY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:GEMIGNANI, VINCENZO;FAITA, FRANCESCO;BIANCHINI, ELISABETTA;REEL/FRAME:028126/0761
Owner name: CNR-DIPARTIMENTO DI MEDICINA, ITALY