DEVICE AND METHOD FOR ASSESSING CARDIOVASCULAR ACTIVITIES USING ULTRASOUND

Description

Domaine technique

[0001] This description relates generally to electronic devices, and more specifically to devices and methods for evaluating cardiovascular activity by ultrasound. Technique antérieure

[0002] We know of electronic devices and methods for evaluating cardiovascular activity that allow, for example, the detection of malfunctions that may affect a human cardiovascular system, the monitoring of a clinical condition of a patient with cardiovascular disease, or the tracking of changes in an athlete's cardiovascular parameters during a sporting performance.

[0003] Document FR 2759892 describes an ultrasonic ultrasound system for examining arteries. US patent application 2004 / 138568 A1 describes an electronic device with two ultrasound probes for evaluating a user's pulse, said device being worn on the wrist. Summary of the invention

[0004] One objective of an embodiment is to overcome all or part of the drawbacks of known devices and methods for assessing cardiovascular activity. More specifically, one objective of an embodiment is to provide a portable electronic device for assessing cardiovascular activity, with external dimensions compatible with wearing on a user's wrist.

[0005] The invention is defined by claim 1. The dependent claims cover embodiments and variants of the invention. Brève description des dessins

[0006] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the attached figures, among which: there figure 1 is a top view illustrating, schematically and partially, an example of a portable electronic device for assessing cardiovascular activity according to one embodiment; the figure 2 is a cross-sectional view, according to plane AA of the figure 1 , of the device of the figure 1 in an initial usage configuration; the figure 3 is a cross-sectional view, according to plane AA of the figure 1 , of the device of the figure 1 in a second usage configuration; the figure 4 represents, schematically and partially, an example of the implementation of a control circuit for the device of the figure 1 ; there figure 5 represents, schematically and partially, another example of the implementation of the control circuit of the device of the figure 1 ; and the figure 6 illustrates an example of the integration of the device of the figure 1 in a smartwatch worn on a user's wrist. Description des modes de réalisation

[0007] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0008] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, the various applications of the devices and methods described have not been detailed, as the described embodiments are compatible with all or most applications that could benefit from a device or method for estimating cardiovascular activity. Furthermore, the ultrasonic transducers of the device's probes have not been detailed, as the fabrication and practical implementation of these transducers are within the capabilities of a person skilled in the art, based on the information provided in this description.

[0009] Unless otherwise specified, when referring to two connected elements, this means directly connected without any intermediate elements other than conductors, and when referring to two coupled elements, this means that these two elements can be connected or linked through one or more other elements.

[0010] In the description that follows, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative positional qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientational qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0011] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean to within 10%, preferably to within 5%, or, when referring to an angular value, to within 10°, preferably to within 5°.

[0012] There figure 1 is a top view illustrating, schematically and partially, an example of a portable electronic device 100 for evaluating cardiovascular activity by ultrasound according to one embodiment.

[0013] In the example shown, the device 100 comprises first, second, and third probes 101A, 101B, 101C, each with an array of ultrasonic transducers 103A, 103B, and 103C, respectively. In the example shown, the transducer arrays 103A, 103B, and 103C are substantially linear. Alternatively, each transducer array 103A, 103B, and 103C may have a non-rectilinear shape, for example, a curved one. Furthermore, it has been illustrated in figure 1 An example in which the transducers 103A, 103B, 103C of the same strip have virtually identical external dimensions, within manufacturing variations, and are regularly spaced. However, alternatively, the transducers 103A, 103B, 103C of the same strip may have different dimensions and variable spacing.

[0014] The first and second ultrasonic probes 101A, 101B are located on either side of the third ultrasonic probe 101C and are substantially parallel to each other. The third probe 101C is substantially perpendicular to the first and second probes 101A, 101B. In this example, the first, second, and third probes 101A, 101B, 101C, viewed from above, have a general H shape, with the first and second probes 101A, 101B forming the two vertical bars of the H and the third probe 101C forming the horizontal bar of the H.

[0015] In the example illustrated in figure 1 The probes 101A and 101B each contain eight ultrasonic transducers 103A and 103B, and probe 101C contains sixteen ultrasonic transducers 103C. However, probes 101A, 101B, and 101C may contain different numbers of ultrasonic transducers 103A, 103B, and 103C than those shown. For example, the number of ultrasonic transducers 103A, 103B, and 103C in each array corresponds to a power of two, and the number of ultrasonic transducers 103C in the central probe 101C is twice the number of ultrasonic transducers 103A and 103B in each of the two lateral probes 101A and 101B. For example, the ultrasonic transducers 103A, 103B, 103C each have a roughly rectangular shape.In addition, the 103C transducers can be narrower than the 103A, 103B transducers so that the 101C probe has a higher lateral resolution than the 101A, 101B probes, for example in a case where the 101C probe is used in mode B, or to perform an electronically deflected Doppler shot, and the 101A, 101B probes are used in mode A as will be explained in more detail later.

[0016] In the example shown, the portable electronic device 100 is positioned above a blood vessel 150, for example an artery, one wall of which is symbolized, in figure 1 , by two dotted lines. For the sake of simplicity, the thickness of the blood vessel 150 is neglected, the two dotted lines of the figure 1 thus being able to symbolize indifferently the internal or external walls of the blood vessel 150. In this example, the ultrasonic transducer arrays 103A, 103B of the first and second probes 101A, 101B are oriented transversely with respect to the blood vessel 150, and the ultrasonic transducer array 103C of the third probe 101C is oriented longitudinally with respect to the blood vessel 150. More precisely, in the illustrated example, the ultrasonic transducer array 103C is substantially parallel to an Ox axis, along which the blood vessel 150 extends laterally, while the ultrasonic transducer arrays 103A, 103B are substantially parallel to an Oy axis, perpendicular to the Ox axis. For example, in a case where device 100 is worn on a user's arm or wrist, blood vessel 150 is the ulnar artery.

[0017] For the sake of simplicity, it has been represented in figure 1 An example in which blood vessel 150 is substantially straight and has a cross-section of shape, for example circular, and of substantially constant dimensions along its entire length. However, in practice, blood vessel 150 may have any shape, for example a curved shape, and a cross-section of variable shape and dimensions over all or part of its length. Furthermore, it has been shown in figure 1 an example in which the ultrasonic transducer arrays 103A, 103B, 103C are substantially centered with respect to the blood vessel 150. This example is not limiting however, the ultrasonic transducer arrays 103A, 103B, 103C can be decentered, for example offset along the Oy axis, with respect to the blood vessel 150.

[0018] For the sake of clarity, the drawing has been illustrated in figure 1 an example in which the blood vessel 150 has a diameter greater than the length (dimension taken along the Oy axis) of the transducers 103C. The blood vessel 150 may however have different proportions relative to the transducers 103C, for example a diameter approximately equal to the length of the transducers 103C, or a diameter less than the length of the transducers 103C.

[0019] There figure 2 is a cross-sectional view, according to plane AA of the figure 1 , of the portable electronic device 100 for evaluating human cardiovascular activity in a first configuration of use.

[0020] In this operating configuration, the blood vessel 150 is substantially parallel to a substantially flat lower face 100I of the device 100. More precisely, the blood vessel 150 has a median axis 150M parallel to the Ox axis, the lower face 100I of the device 100 being parallel to the Oxy plane. In the example shown, the ultrasonic transducers 103A, 103B, 103C are substantially equidistant from the median axis 150M of the blood vessel 150. In other words, in this example, the blood vessel 150 extends laterally beneath the ultrasonic transducers 103A, 103B, 103C at a substantially constant depth P. In the orientation of the figure 2 , the depth P corresponds to a distance, measured along the vertical axis Oz, between the lower face 100I of the device 100 and the median axis 150M of the blood vessel 150. As an example, the lower face 100I of the device 100 is placed on and in contact with the skin of an arm 151 of the user.

[0021] The ultrasonic transducers 103A, 103B of the probes 101A, 101B of the device 100 allow, for example, the estimation of a volumetric flow rate Dv of blood circulating within a portion of the blood vessel 150 located below the device 100, for example by a pulse wave velocity (PWV) determination method. The pulse wave velocity, denoted PWV, is calculated, for example, from a measurement of the pulse wave propagation time (PTT), produced with each heartbeat, between the ultrasonic transducers 103A and 103B.

[0022] To this end, device 100 records, for example, temporal changes DA(t), DB(t) of a diameter D of blood vessel 150, measured at two distinct locations separated by a distance L, for example, directly above probes 101A and 101B. A phase shift measurement Δt between the temporal changes DA(t), DB(t) of diameter D, recorded respectively by probes 101A and 101B following the same heartbeat, allows us to estimate the pulse wave propagation time between these probes. Knowing the distance L separating probes 101A and 101B, we can then calculate the pulse wave propagation velocity VOP within blood vessel 150 (VOP = L / Δt).

[0023] As an example, the temporal variations DA(t), DB(t) of the diameter D of blood vessel 150 are evaluated in A-mode. In this mode, the amplitude of a returned echo signal is measured as a function of depth. Alternatively, the temporal variations DA(t), DB(t) of the diameter D of blood vessel 150 can be evaluated from images acquired in B-mode. In this mode, two-dimensional ultrasound images are acquired, composed of bright dots representing ultrasound echoes, the brightness of each dot being determined by the amplitude of the returned echo signal.

[0024] In addition, the ultrasonic transducers 103C of the third probe 101C can allow estimation of the volumetric flow rate D v of the blood circulating within the portion of the blood vessel 150 located below the device 100. The estimation of the flow rate D v by the probe 101C is for example carried out by Doppler effect.

[0025] In this case, the ultrasonic transducers 103C are, for example, controlled to emit an incident ultrasonic beam 201 towards the blood vessel 150, and to receive an ultrasonic beam reflected by the blood flowing inside the blood vessel 150. The incident ultrasonic beam 201 corresponds, for example, to a pulsed signal of frequency fi, and the reflected ultrasonic beam corresponds, for example, to a pulsed signal of frequency fr. By measuring a frequency shift between the incident and reflected signals, that is, by measuring a difference between the frequencies fr and fi, the velocity v of blood flow inside the blood vessel 150 can be determined. Furthermore, measurements of the diameter D allow for the estimation of a cross-sectional area S of the blood vessel 150 under the device 100. The cross-sectional area S corresponds, for example, to the surface area of ​​a cross-section of the blood vessel 150.By multiplying the cross-section S of blood vessel 150 by the velocity v of blood flow through this cross-section, we can then go back to the volumetric flow rate D v of blood inside blood vessel 150 (D v = S*v).

[0026] As an example, the diameter D of blood vessel 150 is evaluated, in mode A or mode B, by the ultrasonic transducers 103C of probe 101C. As an alternative, the diameter D of the blood vessel can be evaluated, in mode A or mode B, by the ultrasonic transducers 103A of probe 101A and / or by the ultrasonic transducers 103B of probe 101B as previously described.

[0027] When estimating blood flow Δv using the Doppler effect, the incident ultrasound beam 201 emitted by the ultrasound transducer array 103C has an emission direction forming, for example, an angle α, called the steering angle, with respect to a normal to the lower surface 100I of the device 100. To obtain optimal measurement accuracy of the velocity v, the angle α is adjusted, for example, so that the ultrasound beam 201 reaches the blood vessel 150 at a small angle of incidence θ, called the Doppler angle. As an example, the angle θ is between 30° and 60°.

[0028] Furthermore, the incident ultrasound beam 201 is focused, for example, at the mid-axis 150M of the blood vessel 150, i.e., at depth P below the device 100, in this example. This allows, for example, the velocity v to be measured at the center of the flow and not near the walls of the blood vessel 150. This results in greater measurement accuracy.

[0029] As an alternative, the 101C probe can be used to perform B-mode ultrasound imaging, specifically high-frequency plane wave imaging (PWI). From the images thus obtained, the diameter D of the blood vessel 150 and the blood flow velocity v can, for example, be estimated using a technique called vector flow imaging (VFI).

[0030] There figure 3 is a cross-sectional view, according to plane AA of the figure 1 , of the portable electronic device 100 for assessing human cardiovascular activity in a second usage configuration.

[0031] In this usage configuration, the blood vessel 150 is inclined relative to the device 100. More precisely, the blood vessel 150 is, in this example, parallel to the Oxz plane and inclined at an angle φ to the horizontal Ox axis, with the lower face 100I of the device 100 being parallel to the Oxy plane. In this example, the ultrasonic transducers 103B of the second probe 101B are farther from the median axis 150M of the blood vessel 150 than the ultrasonic transducers 103A of the first probe 101A. More precisely, in the example illustrated in figure 3 The median axis 150M of blood vessel 150 is located at a depth PA below the ultrasound transducers 103A and at another depth PB, greater than the depth PA, below the ultrasound transducers 103B. In the orientation of the figure 3 , the depths PA, PB correspond to distance measurements along the vertical axis Oz.

[0032] In the example illustrated in figure 3 The inclination of blood vessel 150 alters the angle of incidence of the incident ultrasound beam 201 emitted by probe 101C towards blood vessel 150. More precisely, in this example, beam 201 reaches blood vessel 150 at an angle of incidence θ' less than the angle θ (θ' = θ + φ). This tends to degrade the accuracy of the velocity measurement v, and therefore the estimation of the volumetric flow rate Dv of blood within blood vessel 150.

[0033] Furthermore, in the example illustrated in figure 3 The angle φ of inclination of the blood vessel 150 tends to cause the incident ultrasound beam 201 emitted by the probe 101C to focus in an area far from the median axis 150M, that is, closer to the walls of the blood vessel 150M than in the example illustrated in figure 2 This also tends to degrade the accuracy of the velocity measurement v, and therefore of the flow rate D v.

[0034] According to one embodiment, the lateral arrays of ultrasonic transducers 103A, 103B located on either side of the central array of ultrasonic transducers 103C are used to emit ultrasonic beams to estimate the position of the blood vessel 150 relative to the device 100. Depending on the estimated position of the blood vessel 150, the ultrasonic beam 201 emitted by the third probe 101C is then adjusted.

[0035] More specifically, the ultrasonic transducers 103A emit, for example, a first ultrasonic beam allowing the position, for example the depth PA along the Oz axis, at which the blood vessel 150 is located directly above the probe 101A, to be estimated. Similarly, the ultrasonic transducers 103B emit, for example, a second ultrasonic beam allowing the position, for example the depth DB along the Oz axis, at which the blood vessel 150 is located directly above the probe 101B to be determined. From the depths PA and PB, and knowing the distance L separating the probes 101A and 101B, the angle φ of inclination of the blood vessel 150 with respect to the Ox axis can be determined, for example by considering that the portion of the blood vessel 150 located below the device 100 is substantially straight.The estimation of the angle φ thus obtained makes it possible, for example, to advantageously compensate for the inclination of the blood vessel 150 when measuring the velocity v by Doppler effect, for example by emitting with the central probe 101C an incident ultrasonic beam 201' forming an angle α' with the normal to the lower surface 100I of the device 100. The angle α' is, for example, adjusted so that the ultrasonic beam 201' reaches the blood vessel 150 at an angle of incidence as close as possible to the angle θ (equal to the angle θ, in the example illustrated in . figure 3 ).

[0036] Estimating the angle φ, using the lateral probes 101A, 101B of the device 100, also allows for modifying the focal length of the incident ultrasound beam emitted by the central probe 101C. In the example shown, the incident ultrasound beam 201' is focused near the median axis 150M of the blood vessel 150, which again compensates for the inclination of the blood vessel 150 relative to the device 100 and advantageously yields more precise measurements than if the probe 101C emitted the ultrasound beam 201.

[0037] Furthermore, the ultrasound beams emitted by the lateral probes 101A, 101B can be adjusted according to the estimated position of the blood vessel 150. More specifically, the emission direction and focal length of the ultrasound beams emitted by the ultrasound transducer arrays 103A, 103B can be adjusted according to the estimated position of the blood vessel 150. Alternatively, once the position of the blood vessel 150 has been detected by the probes 101A, 101B, only a portion of the ultrasound transducers 103A, 103B, for example the ultrasound transducer 103A, 103B of each array closest to the median axis 150M, can be used to monitor the temporal evolution of the diameter D.

[0038] In the case where probes 101A, 101B implement the pulse wave velocity determination method by pulse transit time measurement previously described in relation to the figure 2 The estimation of the position of blood vessel 150 relative to device 100 can also be advantageously used to compensate for a distance error between the diameter measurement zones D directly above the ultrasonic transducers 103A, 103B. In the example of the figure 3 These zones are indeed separated by a distance L' not equal to the distance L between probes 101A and 101B, as in the example illustrated in figure 2 , but equal to L*cos(φ).

[0039] We illustrated in figure 3 an example in which the median axis 150M of blood vessel 150 is inclined at a negative angle φ with respect to the Ox axis and in which the ultrasound beam 201' is directed downstream of blood vessel 150 (to the right, in the orientation of the figure 3 As an alternative, blood vessel 150 could be inclined at a positive angle φ with respect to the Ox axis, in which case depth PA would be greater than depth PB. The inclination of blood vessel 150 would then be compensated for, for example, by adjusting angle α' so that the ultrasound beam 201' reaches blood vessel 150 at an angle of incidence between 120° and 150°. In this case, the ultrasound beam 201' would be directed upstream of blood vessel 150 (to the left, in the orientation of the figure 3 ).

[0040] Although an example has been described above in which blood vessel 150 is parallel to the Oxz plane and inclined with respect to the Ox angle, the embodiments described also apply to cases in which blood vessel 150 has any orientation in space. For example, the embodiments described can be transposed by a person skilled in the art to cases in which blood vessel 150 is parallel to the Oxy plane and inclined with respect to the Ox axis, and to cases in which blood vessel 150 is parallel to neither the Oxz plane nor the Oxy plane.

[0041] Furthermore, embodiments have been described above in which the direction and / or focal length of the ultrasonic beams emitted by the ultrasonic transducer arrays 103A, 103B, 103C can be adjusted according to the estimated position of the blood vessel 150. However, it would also be possible to take advantage of the estimation of the position of the blood vessel 150 relative to the device 100 to compensate for measurements made by the probes 101A, 101B, 101C without changing the direction and / or focal length of the ultrasonic beams they emit, or in addition to such changes.

[0042] Furthermore, although an example has been described in which both lateral transducer arrays 103A and 103B are used to estimate the position of blood vessel 150, it could be considered, as an alternative, to use only one lateral transducer array, for example the 103A transducers of probe 101A or the 103B transducers of probe 101B, to estimate the position of blood vessel 150. This alternative is within the grasp of a person skilled in the art based on the indications in this description.

[0043] There figure 4 represents, schematically and partially, an example of the implementation of a control circuit 400 of the device 100 of the figure 1 .

[0044] In the example shown, the 400 circuit includes two pulse generators 401AB, 401C ("pulser" in English), also called transmission circuits. The pulse generator 401AB is, for example, connected to the ultrasonic transducers 103A, 103B of the side probes 101A, 101B, and the pulse generator 401C is, for example, connected to the ultrasonic transducers 103C of the central probe 101C. In this example, each pulse generator 401AB, 401C has, for each ultrasonic transducer 103A, 103B, 103C to which it is connected, one channel 403. As an example, in the case where the side probe arrays 101A, 101B each have eight ultrasonic transducers 103A, 103B and where the central probe array 101C has sixteen ultrasonic transducers 103C, each pulse generator 401AB, 401C has sixteen identical channels 403, within manufacturing variations.As an example, the 401AB and 401C pulse generators are identical, except for manufacturing variations.

[0045] In the example shown, each channel 403 more precisely comprises an amplifier 405 (HV), for example a high-voltage amplifier, a transmit beam former 407 (TX BF), and a transmit-receive switch 409. In the example illustrated in figure 4 The beam former 407 has an input connected to an output of a processing unit 411 (PU), for example a field-programmable gate array (FPGA), and an output connected to an input of the high-voltage amplifier 405. The amplifier 405 has an output connected to one of the terminals of the switch 409 and to one of the ultrasonic transducers 103A, 103B, or 103C. In this example, the other terminal of each switch 409 is connected to an analog front end 421, also called a receiver circuit.

[0046] The receiving circuit 421 comprises a plurality of receiving channels 423. In this example, the circuit 421 has a number of receiving channels 423 equal to half the number of ultrasonic transducers 103A, 103B, 103C of the device 100. For example, in the case where the side probe arrays 101A, 101B each have eight ultrasonic transducers 103A, 103B and the central probe array 101C has sixteen ultrasonic transducers, the circuit 421 has sixteen identical channels 423, within manufacturing variations.

[0047] In the example shown, each channel 423 specifically comprises an amplifier 425 (LNA), for example, a low-noise amplifier, an amplifier 427 (PGA), for example, a programmable-gain amplifier, a low-pass filter 429 (LPF), an analog-to-digital converter 431 (ADC), and a serial converter 433 (LVDS), for example, a converter capable of operating in low-voltage differential signaling. In this example, the amplifier 425 for each channel 423 has an input connected to one of the channels 403 of the pulse generator 401AB and to one of the channels 403 of the pulse generator 401C, and an output connected to an input of the amplifier 427. The amplifier 427 has an output connected to an input of the filter 429. The converter 431 has an input connected to the filter 429 and an output connected to an input of the serial converter 433.In the example shown, amplifiers 425 and 427, filter 429 and converter 431 each have a control input connected to an output of processing unit 411. In addition, each channel 423 of circuit 421 has an output, corresponding to an output of serial converter 433, connected to processing unit 411.

[0048] An example of the operation of device 100 associated with circuit 400 will now be described in relation to the figure 4 .

[0049] During the first transmission stage, the switches 409 of the pulse generator 401AB are, for example, all in the open state, and ultrasonic beams are emitted by the side probes 101A and 101B. During the first transmission stage, the processing unit 411 is, for example, configured to transmit no signal to the beam formers 407 of the pulse generator 401C, so probe 101C does not emit any ultrasonic beam. Then, during a first reception stage following the first transmission stage, all the switches 409 of the pulse generator 401AB are closed, for example, to allow the side probes 101A and 101B to detect ultrasonic echoes. In this example, the position of blood vessel 150 relative to device 100 is estimated at the end of the first reception step.

[0050] Then, in a second transmission step following the first reception step, all switches 409 of the pulse generator 401C are open, and ultrasonic beams are emitted by the central probe 101C. During the second transmission step, the processing unit 411 is configured, for example, to transmit no signal to the beam formers 407 of the pulse generator 401AB, so probes 101A and 101B do not emit any ultrasonic beams. Finally, in a second reception step following the second transmission step, all switches 409 of the pulse generator 401C are closed, for example, to allow the central probe 101C to detect ultrasonic echoes. The flow rate measurement Δv is then performed, for example, at the end of the second reception step.

[0051] Once the second reception step is complete, the emission parameters of the beam emitted by the central probe 101C and / or the beams emitted by probes 101A and 101B are adjusted, for example, according to the position of the blood vessel 150 relative to the device 100, as estimated during the first reception step. The previously described emission and reception steps can then be repeated using the modified emission parameters.

[0052] For example, the position of blood vessel 150 is estimated and the emission parameters of probe 101C and / or probes 101A, 101B are modified at the beginning of a phase of a patient's cardiovascular activity assessment. The emission parameters of probe 101C and / or probes 101A, 101B then remain unchanged until the next assessment phase, for example, one performed on another patient. Alternatively, the operations of estimating the position of blood vessel 150 and adjusting the emission parameters of probe 101C and / or probes 101A, 101B can be repeated during the same phase of the patient's cardiovascular activity assessment.

[0053] There figure 5 represents, schematically and partially, an example of the implementation of a control circuit 500 of the device 100 of the figure 1 The 500 circuit of the figure 5 includes common elements with the 400 circuit of the figure 4 .

[0054] The 500 circuit of the figure 5 differs from the 400 circuit of the figure 4 principally in that, in the example shown, the 500 circuit comprises a single pulse generator, for example the 401AB pulse generator previously described in connection with the figure 4 Furthermore, circuit 500 differs from circuit 400 in that it includes a multiplexer 501 (MUX) connecting the ultrasonic transducer arrays 103A, 103B, 103C of the probes 101A, 101B, 101C of device 100 to the pulse generator 401AB. In the example shown, where the device comprises thirty-two ultrasonic transducers 103A, 103B, 103C, the multiplexer 501 more precisely has sixteen channels and is of type 1 to 2.

[0055] As an example, each channel of the 501 multiplexer includes, as in the example illustrated in figure 5 A single-pole double-throw (SPDT) switch 503 has one input terminal connected to one of the channels 403 of the pulse generator 401AB, a first output terminal connected, for example, to one of the ultrasonic transducers 103A, 103B of the side probes 101A, 101B, and a second output terminal connected, for example, to one of the ultrasonic transducers 103C of the center probe 101C. The multiplexer 501 also includes a control input connected to the processing unit 411, allowing, for example, all the switches 503 to be switched between their first and second output terminals, for example, in a substantially simultaneous manner.As an example, the control input receives from the processing unit 411 a control signal whose first level places all the 503 switches in a state where their input terminal is connected to their first output terminal and whose second level places all the 503 switches in another state where their input terminal is connected to their second output terminal.

[0056] An example of the operation of device 100 associated with circuit 500 will now be described in relation to the figure 5 .

[0057] During a first transmission stage, the switches 409 of the pulse generator 401AB are, for example, all in the open state, the switches 503 of the multiplexer 501 are, for example, in the state where their input terminal is connected to their first output terminal, connected to the ultrasonic transducers 103A, 103B in this example, and ultrasonic beams are emitted by the side probes 101A and 101B. Then, during a first reception stage following the first transmission stage, all the switches 409 of the pulse generator 401AB are closed, for example, to allow the side probes 101A, 101B to capture ultrasonic echoes, the switches 503 of the multiplexer 501 remaining in the state where their input terminal is connected to their first output terminal. In this example, the position of blood vessel 150 relative to device 100 is estimated at the end of the first reception step.

[0058] Then, in a second transmission stage subsequent to the first reception stage, the 409 switches of the pulse generator 401AB are, for example, opened, the 503 switches of the multiplexer 501 are, for example, switched to the state in which their input terminal is connected to their second output terminal, connected to the ultrasonic transducers 103C in this example, and ultrasonic beams are emitted by the central probe 101C. Finally, during a second reception stage subsequent to the second transmission stage, for example all the switches 409 of the pulse generator 401AB are closed in order to allow the central probe 101C to capture ultrasonic echoes, the switches 503 of the multiplexer 501 remaining in the state where their input terminal is connected to their second output terminal, in order to allow the central probe 101C to capture ultrasonic echoes.The measurement of the flow rate D v is, for example, carried out at the end of the second reception stage.

[0059] Once the second reception stage is completed, for example, the emission parameters of the beam emitted by the central probe 101C and / or the beams emitted by the probes 101A, 101B are adjusted according to the estimated position of the blood vessel 150 relative to the device 100. The emission and reception stages described above can then be repeated using the modified emission parameters.

[0060] One advantage of the previously described 400 and 500 circuits is that they have a small number of electronic components and channels, making the 400 and 500 circuits and the 100 device compatible with integration into a portable device and with a low acquisition cost.

[0061] There figure 6 illustrates an example of the integration of the 100 device of the figure 1 in a device 600, such as a wristband worn on the user's arm 151, for example, a smartwatch. In the example shown, the device 600 also incorporates the control circuit 500 of the device 100. The device 100 is, for example, located in an area of ​​the device 600 intended to be positioned substantially opposite the ulnar artery 150 of the user's arm 151. As an example, the device 100 is integrated into a wristband 601 of the device 600.

[0062] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to them. In particular, those skilled in the art are able to substitute the control circuit 500 of the device 600 of the figure 6 by the control circuit 400 previously described in relation to the figure 4 .

[0063] Finally, the practical implementation of the described embodiments and variants is within the grasp of a person skilled in the art, based on the functional specifications given above. In particular, the practical implementation of device 100, including the geometry, positioning, and control of the ultrasonic transducers 103A, 103B, 103C of the probes 101A, 101B, 101C of device 100, and the control of the circuit elements 400, 500 by the processing unit 411, are within the grasp of a person skilled in the art, based on the specifications in this description.

Claims

1. Electronic device for assessing a human cardiovascular activity, the device being portable and having outer dimensions compatible with its being worn on a user's wrist, the device comprising first and second probes (101A, 101B) substantially parallel to each other and located on either side of a third probe (101C), substantially perpendicular to the first and second probes, each probe (101A, 101B, 101C) comprising an array of ultrasound transducers (103A, 103B, 103C), and a control circuit (400; 500) comprising a processing unit (411), the control circuit being configured to, using the processing unit (411): a) estimate, by means of a first ultrasound beam emitted by the first probe (101A), a position of a blood vessel (150) with respect to the device; and b) adjust a second ultrasound beam (201; 201'), emitted by the third probe (101C), according to the estimated position of the blood vessel (150).

2. Device according to claim 1, wherein the control circuit is configured to, at step b), adjust a direction of emission of the second ultrasound beam (201; 201') according to the estimated position of the blood vessel (150).

3. Device according to claim 1 or 2, wherein the control circuit is further configured to, at step b), adjust focal distance of the second ultrasound beam (201; 201') according to the estimated position of the blood vessel (150).

4. Device according to any of claims 1 to 3, wherein the control circuit is configured to adjust the first ultrasound beam emitted by the first probe (101A) according to the estimated position of the blood vessel (150).

5. Device according to any of claims 1 to 4, wherein the second probe (101B) is configured to emit a third ultrasound beam.

6. Device according to claim 5, wherein the control circuit is further configured to, during step a), estimate the position of the blood vessel (150) with respect to the device by means of the third ultrasound beam emitted by the second probe (101B).

7. Device according to claim 5 or 6, wherein the control circuit is configured to estimate a pulse wave velocity inside of the blood vessel (150) based on the first and third ultrasound beams respectively emitted by the first and second probes (101A, 101B).

8. Device according to any of claims 1 to 7, wherein the control circuit is further configured to estimate the blood flow rate inside of the blood vessel (150), based on the second ultrasound beam (201; 201'), by Doppler effect.

9. Device according to any of claims 1 to 8, wherein the blood vessel (150) is the ulnar artery.

10. Device according to any of claims 1 to 9, wherein the control circuit (400) comprises a first pulser (401AB) connected to the ultrasound transducers (103A, 103B) of the arrays of the first and second probes (101A, 101B) and a second pulser (401C) connected to the ultrasound transducers (103C) of the array of the third probe (101C).

11. Device according to any of claims 1 to 9, wherein the control circuit (500) comprises a single pulser (401AB) coupled, via a multiplexer (501), to the ultrasound transducers (103A, 103B, 103C) of the arrays of the first, second, and third probes (101A, 101B, 101C).

12. Device according to claim 11, wherein the array of ultrasound transducers (103C) of the third probe (101C) comprises twice more ultrasound transducers (103C) than each of the arrays of ultrasound transducers (103A, 103B) of the first and second probes (101A, 101B), the multiplexer (501) being a 1-to-2 multiplexer.

13. Connected watch (600) or bracelet comprising a device according to any of claims 1 to 12.

14. Method of assessment of a human cardiovascular activity, by an electronic device portable and having outer dimensions compatible with its being worn on a user's wrist and comprising first and second probes (101A, 101B) substantially parallel to each other and located on either side of a third probe (101C), substantially perpendicular to the first and second probes, each probe (101A, 101B, 101C) comprising an array of ultrasound transducers (103A, 103B, 103C), and a control circuit (400; 500) comprising a processing unit (411), the method comprising the following steps, implemented by the control circuit using the processing unit (411): a) estimate, by means of a first ultrasound beam emitted by the first probe (101A), a position of a blood vessel (150) with respect to the device; and b) adjust a second ultrasound beam (201; 201'), emitted by the third probe (101C), according to the estimated position of the blood vessel (150).

15. Method according to claim 14, wherein, at step a), the position of the blood vessel (150) with respect to the device is further estimated by a third ultrasound beam emitted by the second probe (101B).