WO2020165758A1

WO2020165758A1 - Device and method for cardiopathies assessment

Info

Publication number: WO2020165758A1
Application number: PCT/IB2020/051077
Authority: WO
Inventors: Hugo Humberto PLÁCIDO DA SILVA; Mónica Cristina MONTEIRO MARTINS; Miguel TAVARES COIMBRA; Pedro Tiago MAGALHÃES GOMES
Original assignee: Universidade Do Porto; Instituto De Telecomunicações; Universidade De Coimbra
Priority date: 2019-02-11
Filing date: 2020-02-11
Publication date: 2020-08-20

Abstract

The present invention is related to a medical device for cardiopathies assessment comprising a computational unit and a sensory unit designed to synchronously measure phonocardiographic (PCG), electrocardiographic (ECG) and functional near infrared spectroscopy (fNIRS) signals incorporating a standard electronic stethoscope or a purpose-built device. The sensory unit (408) comprises an electronic module through which at least ECG and fNIRS are acquired, and an electronic module that produces a synchronization signal shared with the electronic stethoscope.The device can be used in alternative or as a complement to existing systems that only perform a measurement of PCG. It can be applied to electronic stethoscopes, conventional stethoscopes, or analogous assemblies.The present invention is thus in the area of medical devices with signal measurement for medical decision support purposes.

Description

DESCRIPTION

DEVICE AND METHOD FOR CARDIOPATHIES ASSESSMENT

Field of the invention

The present invention is related to a medical device for the cardiopathies assessment comprising a computational unit and a sensory unit designed to synchronously measure phonocardiographic (PCG) , electrocardiographic (ECG) and functional near infrared spectroscopy (fNIRS) signals incorporating a standard electronic stethoscope or a purpose- built device.

The sensory unit has an electronic module through which at least ECG and fNIRS are acquired, and an electronic module that produces a synchronization signal shared with the electronic stethoscope, although it can also integrate an electronic module through which the PCG is acquired.

The operating principle of this medical device is provided to ensure the improved quality of the collected signals even in the presence of natural barriers like androgenic hair, and the synchronization of all acquired data enabling the automated recognition or validation of cardiopathies in patients.

Furthermore, the medical device integrates an inertial measurement unit (IMU), which assists the ECG signal correction due to the effect of rotations in the placement of the auscultation head with respect to the electrical axis of the heart .

The present invention is thus in the area of medical devices with signal measurement for cardiopathies assessment purposes. State-of-the-art

Each cardiac cycle is composed by a chain of biomechanical events, triggered by a bioelectrical activation signal inflicted on the cardiac muscle. This signal is produced by an element of the cardiac system known as sinoatrial (SA) node, which is controlled by the autonomic nervous system, and works as a natural pacemaker. The signal is then propagated through the atrioventricular node (AV) node, connecting the atria and the ventricles. Right after, the AV node gives rise to the Bundle of His and, more distally, this one separates into two branches, ending in the Purkinje fibres. Finally, the Purkinje fibres diverge and the impulse passes from the inner side of the ventricle walls to the outer side, due to cell-to-cell activation. This process has bioelectrical and biomechanical manifestations, which can be measured through different techniques .

Auscultation is a widespread routine exam for basic cardiopulmonary assessment, performed in most typical appointments with a medical professional, which allows a quick preliminary evaluation of the subjects' heart and lung condition. However, auscultation relies on the human ear, which may not be sufficient for an accurate evaluation of the patient [1] . The main problem with this technique is that it is difficult to master [2], and specialized healthcare professionals are required in order to perform a standard medical evaluation. Also, the fact that it does not allow the automated recording of any information for later analysis, stands out as a significant limitation of the auscultation process . Digital stethoscopes appeared as a response to some of these problems, by combining auscultation with the digital recording of the cardiac sounds, i.e. phonocardiography (PCG) [3] . The PCG exam provides information about the cardiac activity through its sounds, which are in the range [10, 750] Hz. For cardiac assessment, these sounds are typically heard over 5 auscultation points, namely second intercostal space on the right parasternal line (FI), second intercostal space in the left parasternal line (F2), third intercostal space in the left parasternal line (F3), lower left border of the sternum (F4) and fourth/fifth intercostal space in the left hemiclavicular line (F5) . With the help of a PCG record, it is possible to determine the temporal localization of heart sounds, the number of their internal components, their frequency content and the significance of diastolic and systolic murmurs [4] .

One of the most widespread techniques for accurate cardiac assessment, however, is the analysis of the electrical activity of the heart. This is usually known as electrocardiography (ECG) , and consists of measuring the voltage variations as a function of time, in result of successive myocardium depolarization and repolarization events. On ECG signals, each cardiac cycle is generally characterized as a series of complexes (P-QRS-T) , which are associated with the propagation of the electrical activation signal throughout the cardiac muscle as initially described [5] .

The ECG is captured, in general, externally, through electrodes applied on the body surface over the heart or around its vicinity. For clinical diagnosis, typically 12 recording leads are used. Willem Einthoven idealized the cardiac electrical activity acquisition through three bipolar leads placed on the frontal plane, in which the heart is located at the centre. This triangle is formed by three main points, in which the electrodes are located, namely right arm (R) , left arm (L) and left leg (F), the latter being the ground. If two of those points are chosen, we can obtain the difference of potential between the positive electrode placed on the left arm and the negative one on the right arm (Lead I), the difference of potential between the right arm and left leg (Lead II), and the difference of potential between the left arm and left leg (Lead III) .

If we move all three leads to the centre of the triangle, three intersection lines emerge, corresponding to three additional leads, namely the augmented vector right measuring the absolute potential through the positive electrode placed on the right arm (aVR) , the augmented vector foot measuring the absolute potential through the positive electrode placed on the left leg (aVF) , and the augmented vector left measuring the absolute potential through the positive electrode placed on the left arm (aVL) .

So far, only limb leads have been mentioned, namely the bipolar limb leads (Leads I, II and III) and unipolar limb leads (aVL, aVR and aVF) . The remaining 6 leads are the precordial (or chest) leads, and measure electrical activity in the traverse plane, instead of the frontal. In this case, the reference is in the center of the chest and the electrodes are placed around it; the points VI and V2 are located at the fourth intercostal space on the right and left side of the sternum, V4 is located in the fifth intercostal space, V3 is located between the points V2 and V4, V5 is at the same horizontal level as V4, and V6 is at the same horizontal level as V4 but at the midline Another aspect of the cardiovascular dynamics is the perfusion of the blood flow throughout the microvascular bed of tissues; this has been amply studied within the state-of-the-art by means of photoplethysmographic (PPG) signal acquisition, however, recent advances in functional near-infrared spectroscopy (fNIRS), made it possible to study hemodynamic responses, going beyond the more simplistic metrics that can be derived from PPG.

To the best of our knowledge, the use of fNIRS in conjunction with PCG has not been explored, however, the combination of PCG and ECG exams has been explored in the state-of-art, although mostly as a way of using ECG signals to assist in the segmentation of PCG signals due to noise and other artifacts. For this purpose, less intrusive ECG acquisition setups have been devised, which integrate a single lead ECG and a digital stethoscope for PCG, and several devices that ally both exams have already emerged.

Document US15712469 discloses a non-invasive system for detecting and processing PCG and electrocardiography ECG signals, comprising an electronic acoustic stethoscope that includes an earpiece and a chest-piece, wherein the chest- piece includes an acoustic transducer, at least four electrodes, a wireless communication device, and at least one processor, wherein the acoustic transducer is adapted to contact the skin of a patient, measure heart sounds of the patient, and send the heart sounds to the earpiece and the at least one processor is adapted to create a PCG waveform of the heart sounds, wherein the at least four electrodes are adapted to contact the skin of the patient and measure heart electrical signals of the patient and the at least one processor is adapted to create an ECG waveform of the heart electrical signals, wherein the wireless communication device is adapted to transmit the PCG waveform and/or the ECG waveform.

Document US9736625 discloses a method for transmitting cardiac data from a wireless sensor to a host device, the method comprising digitizing cardiac sound data and ECG data received at the wireless sensor, filtering the digitized cardiac sound data and ECG data, compressing the cardiac sound data and the ECG data using an adaptive differential compression component, combining the compressed cardiac sound data and compressed ECG data into a common packet structure, and transmitting the common packet structure from the wireless sensor to the host device via a Bluetooth Low Energy communications link [7] . This is one of the technologies incorporated in the Eko DUO device that combines an electronic stethoscope for PCG data acquisition with a single-lead ECG sensor [8] .

Document CN204181639U discloses an ECG multifunctional stethoscope auscultation head including, hoses, U-shaped tube, signal processing unit, earpiece, a storage device, a liquid crystal display, a keypad module, USB interface, a wireless communication and a power supply module. The auscultation head membrane is provided with a circular metal frame on the outside of the auscultation film, and the signal processing unit measures a digital amplified and filtered ECG signal, displayed by the liquid crystal display.

Document CN201139576Y discloses a stethoscope with ECG capabilities comprising a head, auscultation box and stethoscope. In a three electrodes extending pawl are disposed three electrodes in the outer end and a sensor module; the sensor module comprises a sound focusing device and a sound sensor; a display screen is also provided, together with a surface auscultation cartridge; the auscultation cartridge comprises a data processing unit with a signal amplification circuit, an analogue-to-digital (A/D) conversion circuit, and a microprocessor to which the three ECG electrodes and the acoustic sensor are connected.

Document CN2754560Y discloses an electronic stethoscope with ECG capabilities, composed of an earplug, conduit and the stethoscope head, characterized in that the stethoscope is equipped with a battery box and an electrode lead with a movable electrode. Said stethoscope head is mounted on a LCD display in which there is a fixed electrode and sound auscultation device. In the battery case there is a control circuit, a microprocessor unit, a display circuit, a function switching circuit, an auscultation circuit, an ECG amplification circuit and a RS232 interface circuit.

Document US20010030077A1 discloses a personally portable ECG stethoscope system for auscultating a living body, the system including an electronic stethoscope head and standard air tube assembly, the electronic stethoscope head comprising a stethoscope body having a first a second and a third mounting means, the first mounting means being a chest-bell mount adapted for receiving and mounting a chest-bell, the second mounting means being an air tube connector adapted for connecting one or more air tubes to the stethoscope body, and the third mounting means being a display module mount adapted for attaching a display module to the stethoscope body. The author foresees a chest-bell having a base, an opening rim for contacting the living body, and an interior space between the base and the rim, with the base adapted to attach to the first mounting means of the stethoscope body, an electrode assembly having at least two electrodes and electrical leads connected to the electrodes, the electrodes disposed on the rim of the chest-bell to contact the living body during auscultation and receive electrical signals from the living body.

Document US6757392B1 discloses an electronic stethoscope comprising a headpiece connected to a chest-piece by means of a lead, and two earpieces connected to the chest-piece, wherein the headpiece comprises at least three electrodes for obtaining an ECG, a display arrangement for visual display of body function values obtained by the electrodes, and an evaluation unit for collection and processing of the body function values for displaying at the display arrangement.

At least two of the three electrodes are fixed to arms attached pivotably to a periphery of a contact surface of the headpiece, the arms being adapted for swivelling out and forming at least approximately a closed contact ring when in a non-swivelled- out position, and wherein the three electrodes are positionable to form an approximately Einthoven triangle arrangement in a swivelled-out position.

Document KR100490461B1 discloses a stethoscope-like device that converts near-infrared spectroscopy (NIRS) into sound. It has an irradiation and light-receiving fibres, near the affected part-probe unit for irradiating infrared rays in a non-invasive way; through the lead wire connected to a probe portion, the device is able to detect changes in cerebral blood flow based on the output information from the semiconductor laser light source, a light detector, wherein the probe portion is connected to the light-receiving fibre is connected to the irradiation fibre. The device also has a control apparatus including a sound source device for converting a change in the cerebral circulation blood flow to sound pulses, and a pair of lead wires and receivers connected to a sound source device of the control device. The basis of the sound pulses produced by a sound source device allow examining a change in brain function .

Summary of the invention

The present invention is related to a medical device for cardiopathies assessment.

The medical device of the present invention comprises a computational unit and a sensory unit designed to synchronously measure phonocardiographic (PCG) , electrocardiographic (ECG) and functional near infrared spectroscopy (fNIRS) signals incorporating a standard electronic stethoscope or a purpose- built device according to claim 1.

Concerning the ECG, this device uses a virtual ground requiring a minimum of two electrodes, and does not require the electrodes to be detached from the auscultation head. Further, it incorporates an electrode design that is not affected by physiological barriers such as androgenic hair, and is capable of providing a signal highly correlated with standard medical leads .

Concerning the fNIRS component of the device, the sensor is designed in such a way that the blood flow differential can be assessed in addition to the localized blood flow.

Another particularly advantageous feature of this device is that the auscultation head uses an inertial measurement unit (IMU) to account for changes in the placement angle of the device, which affect the output ECG signal due to the different positioning in relation to the electrical axis of the heart.

The invention also discloses several preferred embodiments, namely the integration of the ECG and fNIRS sensors in a detachable diaphragm, and a stethoscope body fully integrated with the PCG, ECG and fNIRS sensors.

Description of the figures

Figure 1 shows a representation of the PCG signal during a series of heartbeat cycles.

Figure 2 shows a representation of the ECG signal during a heartbeat cycle.

Figure 3 shows a representation of the fNIRS signal in the red and infrared range during a series of heartbeat cycles.

Figure 4 represents a block diagram showing the modules of the medical device of the invention to support the cardiopathies assessment based on the acquisition and fusion of PCG, ECG, and fNIRS signals.

Figure 5 represents a schematic view of one of the preferential embodiments of the invention, in which the sensory unit (408) and computational unit (409) are both integrated in the stethoscope head. In this case the sensory unit (408) has the electronic module of measurement terminals (401), embodied as the diaphragm of the stethoscope (503) . The signal acquired by the sensory unit (408) is transmitted to the central processing unit of the stethoscope (503) and either the signal or the result of the cardiopathy assessment process can be represented locally .

Figure 6 represents a schematic view of one of the preferential embodiments of the invention, in which the sensory unit (408) is integrated in the stethoscope head and the computational unit (409) is a separate device. In this case the sensory unit (408) has the electronic module of measurement terminals (401), embodied as the diaphragm of the stethoscope. The signal acquired by the sensory unit (408) is transmitted to the central processing unit of a tablet computer (601) and either the signal or the result of the cardiopathy assessment process can be represented in the graphical representation screen of the tablet computer (602) .

Figure 7 represents a schematic view of one of the preferential embodiments of the invention, in which the sensory unit (408) is integrated in the stethoscope head as an external accessory. The electronic module of measurement terminals (401) is the base of the accessory (703) . The electronic module of ECG transduction and signal conditioning with virtual ground (402) and the electronic module of fNIRS transduction and signal conditioning (403) are integrated on the lateral of the accessory (702) . The electronic module of IMU transduction and signal conditioning (404), the electronic module of analogue- to-digital conversion (406), and the electronic module of signal transmission (407) are integrated on the top of the accessory ( 701 ) .

Figure 8 represents a schematic view of one of the preferential embodiments of the invention, in which the sensory unit (408) is integrated in the stethoscope head as an external accessory. The electronic module of measurement terminals (401) is the base of the accessory (803) . The electronic module of ECG transduction and signal conditioning with virtual ground (402) and the electronic module of fNIRS transduction and signal conditioning (403) are integrated on the lateral of the accessory (802) . The electronic module of IMU transduction and signal conditioning (404), the electronic module of analogue- to-digital conversion (406), and the electronic module of signal transmission (407) are also integrated on the lateral of the accessory (801).

Figure 9 represents a schematic view of one of the preferential embodiments of the electronic module of measurement terminals (401), which integrates the electronic module of ECG transduction and signal conditioning with virtual ground (901), four sets of the electronic module of fNIRS transduction and signal conditioning (902), and one electronic module of PCG transduction and signal conditioning (903) .

Description of the invention

The medical device of the present invention comprises a computational unit and a sensory unit designed to synchronously measure phonocardiographic (PCG) , electrocardiographic (ECG) and functional near infrared spectroscopy (fNIRS) signals incorporating a standard electronic stethoscope or a purpose- built device according to claim 1. Sensory Unit

The sensory unit (408) comprises the electronic modules of: measurement terminals (401) to interface with a subjects body; ECG transduction and signal conditioning with virtual ground (402); fNIRS transduction and signal conditioning (403); inertial measurement unit (IMU) transduction and signal conditioning (404); analogue-to-digital conversion (406); and, signal transmission (407) . Optionally, it can also comprise an electronic module of PCG transduction and signal conditioning (405) . The modules (401), (402), (403), (404) and (405) can also be together referred to as sensor.

The interface with the user is performed through one or more electronic modules of measurement terminals (401), by means of which the ECG, fNIRS and, optionally, the PCG signal traces are acquired. The electronic modules of measurement terminals (401) is designed in such way that the comprised ECG and fNIRS constituents introduce minimal interfere with or do not attenuate the cardiac sounds, which would otherwise degrade the quality of the PCG signals.

For ECG signal acquisition the electronic module of measurement terminals (401) is in direct contact with any part of the user's body. In particular, the cardiac auscultation points FI to F5 are the preferential application points. The electronic module of measurement terminals (401) comprises a set of protuberances, which are particularly advantageous to prevent natural body barriers, such as androgenic hair, from significantly degrading the ECG signal quality. The electronic module of ECG transduction and signal conditioning with virtual ground (402), performs the detection of the underlying physiological processes through the electronic module of measurement terminals (401), filters the resulting signal, and amplifies it so that it can be treated as an electrical quantity. The electronic module of ECG transduction and signal conditioning with virtual ground (402) includes an electromagnetic noise filter, compatible with the transmission of the signals through a wireless connection. As a result of the operation of this module, the electrical quantity is a clean and high definition representation of the ECG signal trace, free of external noise.

For fNIRS signal acquisition the electronic module of measurement terminals (401) is in direct contact with any part of the user's body. In particular, the cardiac auscultation points FI to F5 are the preferential application points. The electronic module of measurement terminals (401) comprises at least one light emitter in the visible range, at least one light emitter in the invisible range, and at least one light receiver capable of measuring light within the emitted ranges. The electronic module of fNIRS transduction and signal conditioning (403), performs the conversion and detection of the underlying physical quantity through the electronic module of measurement terminals (401), filters the resulting signal, and amplifies it so that it can be treated as an electrical quantity. The electronic module of fNIRS transduction and signal conditioning (403) includes an electromagnetic noise filter, compatible with the transmission of the signals through a wireless connection. As a result of the operation of this module, the electrical quantity is a clean and high definition representation of the underlying hemodynamic process, free of external noise.

For the optional PCG signal acquisition, the electronic module of measurement terminals (401) is in direct contact with any part of the user's body. In particular, the cardiac auscultation points FI to F5 are the preferential application points. The electronic module of measurement terminals (401) comprises at least one piezoelectric element capable of measuring the sounds associated with the biomechanical activity of the heart. The electronic module of PCG transduction and signal conditioning (405), performs the conversion and detection of the physical quantity through the electronic module of measurement terminals (401), filters the resulting signal, and amplifies it so that it can be treated as an electrical quantity. The electronic module of PCG transduction and signal conditioning (405) includes an electromagnetic noise filter, compatible with the transmission of the signals through a wireless connection. As a result of the operation of this module, the electrical quantity is a clean and high definition representation of the acoustic activity of the heart, free of external noise.

One particularly advantageous property of our device is the integration of IMU data to compensate distortions on the acquired signals due to rotations or different positioning of the stethoscope head with respect to the electrical axis of the heart. For this reason, the device incorporates an electronic module of IMU transduction and signal conditioning (404), which performs the conversion and detection of the angle of the device, filters the resulting signal, and amplifies it so that it can be treated as an electrical quantity. The electronic module of IMU transduction and signal conditioning (404) includes an electromagnetic noise filter, compatible with the transmission of the signals through a wireless connection, and also a low pass filter to eliminate potential motion-induced artifacts. As a result of the operation of this module, the ECG and fNIRS signals, which are influenced by rotations in the stethoscope head with relation to the subjects' body, are corrected to produce a representation of the underlying physical quantities regardless of the rotation of the stethoscope head with respect to the subjects' body or electrical axis of the heart.

The electronic module of analogue-to-digital conversion (406) transforms the electrical quantities, obtained through the electronic module of ECG transduction and signal conditioning with virtual ground (402), the electronic module of fNIRS transduction and signal conditioning (403), the electronic module of IMU transduction and signal conditioning (404) and, optionally, the electronic module of PCG transduction and signal conditioning (405), into an adequate digital representation manageable in the computational unit (409) .

The electronic module of signal transmission (407) has the purpose of sending the digital representation generated by the electronic module of analogue-to-digital conversion (406) to the computational unit (409) . This process can be performed using a cabled or wireless link, or even be performed through electrical tracks in a printed circuit board.

Computational Unit

The computational unit (409) can be any electronic equipment suitable for digital signal processing, including a central processing unit embedded in the stethoscope head (501), the central processing unit of electronic devices such as tablet computers, or the central processing unit of a dedicated computer (601) . The computational unit (409) can also have any equipment for graphical presentation and representation of the acquired signals and the result of the cardiopathy decision support process, including a local display (502), or electronic devices such as the graphical representation screen of a dedicated computer (602) . This computational unit (409) implements a method that shapes the way in which it operates, enabling the extraction of representative information from the ECG, fNIRS and, optionally, the PCG signals collected from the subject body to which the device is applied, accounting for the position of the stethoscope head with respect to the subjects' body and electrical axis of the heart using IMU data. The corresponding outputs being an auxiliary to support the cardiopathy assessment process, and the production of a technical effect according to the produced decision. This process is preferentially performed in a continuous fashion that is, ensuring that the cardiopathy assessment occurs uninterruptedly while the device is being used, although it can also be performed in a momentary way. The computational unit (409) is also characterized in that it includes a method for customization of its settings as a result of the signals acquired from the subjects' body.

Detailed description of the invention

As previously described, the device in this invention comprises a sensory unit (408) and a computational unit (409), which will be further detailed in this section. The computational unit (409) can be an electronic device of any kind, which changes its behaviour, appearance, settings and properties, according to the output of a method that it implements. Such method uses the ECG, fNIRS, IMU and, optionally, PCG signals collected from the sensory unit (408) and processes them in order to produce an output to support cardiopathy detection of the subject under examination. The electronic module of measurement terminals (401) from the sensory unit (408) can be directly integrated in it, although alternatively, it can also consist of an independent attachment, connected to the remaining modules of the sensory unit (408) through wires or cables with variable length, in order to facilitate the construction of its embodiment.

In the preferred embodiment, the sensory unit (408) incorporates at least two conductive electrodes, not necessarily composed of metallic material (i.e. conductive coatings, films, conductive tapes or other materials that eliminate the need to use any kind of metallic element and conductive gel or paste) , with protuberances designed to go through natural body barriers such as androgenic hair, providing an adequate contact with the body surface to enable ECG signal acquisition. In the preferred embodiment, the sensory unit (408) also incorporates at least one light emitter in the 400 and 700 nanometres visible light range, at least one light emitter in the infrared or ultraviolet light range (i.e. below 400 nanometres or above 700 nanometres), and a light receiver capable of measuring light within the emitted ranges; together these enable fNIRS data acquisition. Optionally, the preferred embodiment of the sensory unit (408) incorporates a piezoelectric element to capture the cardiac sounds. Embodiments of the sensory unit (408) can also incorporate only one or a combination of the previously referred elements. Regardless of the embodiment, the sensory unit (408) always incorporates an IMU by means of which the stethoscope head rotation and overall motion dynamics, with respect to the subjects' body and/or to the electrical axis of the heart can be obtained, for the purpose of correcting the signals accordingly, this being of particular importance on the ECG and/or fNIRS signals. For example, in one of its preferred embodiments, the sensor has an electronic module of measurement terminals (401) which is composed by one piezoelectric element, by one light emitter in the 660 nanometre range, by one light emitter in the 860 nanometre range, by one photodetector capable of measuring wavelengths in the 660 and 860 nanometre range, and by at least two conductive polimeric electrodes that, without requiring the use of conductive gel or paste for a good interface with the skin, enable the measurement of a medical grade ECG signal by placing the stethoscope head in any of the cardiac focuses. The measurement in the analogue domain is performed using an electronic module of ECG signal transduction and conditioning with virtual ground (402), an electronic module of fNIRS signal transduction and conditioning (403), an electronic module of IMU signal transduction and conditioning (404), and an electronic module of PCG signal transduction and conditioning (405) .

The electronic module of ECG signal transduction and conditioning with virtual ground (402) performs the filtering and amplification of the signal, producing a more suitable representation of the physical quantity. The filtering type is band pass, being particularly advantageous in the present invention which, by having a passing band between 0.5 and 40Hz, eliminates the need for the traditional notch filters, allowing an adequate separation between the ECG signal and parasite signals such as motion artifacts, baseline wander, muscle signals, power line interference, among others. Typically, the short diameter of the stethoscope head does not provide a significant voltage potential difference to enable a medical grade ECG signal to be measured. In our approach, the electronic module of ECG signal transduction and conditioning with virtual ground (402) comprises an amplifier with gain between 10 and 10000, allowing the increase in the definition of the collected signal (in the order of uV, mV or V) , making the tenuous ECG signals more immune to external noise, and enabling a sufficient definition for the cardiopathy detection support method to operate.

The physical placement of this module with respect to the electronic module of measurement terminals (401) is also particularly advantageous in the invention. Although several other configurations are admissible in the context of the invention, the placement of this module directly in the stethoscope head, and consequently near the point of interface with the subject body, greatly minimizes the appearance of parasite signals. In the traditional signal acquisition methods, this module is placed away from the point of interface with the subject body, making the cabled connection work as an antenna that captures several surrounding noise sources.

The electronic module of fNIRS signal transduction and conditioning (403) performs the filtering and amplification of the signal, producing a more suitable representation of the physical quantity. The filtering type is low pass, being particularly advantageous in the present invention which, by having a cut-off frequency of 40Hz, eliminates the need for the traditional notch filters, allowing an adequate separation between the fNIRS signal and parasite signals such as motion artifacts, external light sources interference, among others. The amplification has a gain between 2 and 1000, allowing the increase in the definition of the collected signal, making the tenuous fNIRS signals collected at the chest (where there is lower superficial perfusion) more immune to external noise, and enabling a sufficient definition for the cardiopathy detection support method to operate.

The physical placement of this module with respect to the electronic module of measurement terminals (401) is also particularly advantageous in the invention. Although several other configurations are admissible in the context of the invention, the placement of this module directly in the stethoscope head, and consequently near the point of interface with the subject body, greatly minimizes the appearance of parasite signals.

The electronic module of IMU signal transduction and conditioning (404) comprises a motion sensor with 9 degrees of freedom capable of measuring linear acceleration in X, Y & Z, centripetal acceleration in X, Y & Z, and the direction of the earth magnetic field in X, Y & Z, and performs the filtering and amplification of each of these signals, producing a more suitable representation of the physical quantity. The filtering type is low pass, being particularly advantageous in the present invention in which, by having a cut-off frequency of 10Hz, allows an adequate separation between the IMU signals and parasite signals such as motion artifacts and analogous noise sources. The amplification has a gain between 2 and 1000, allowing the increase in the definition of the collected signal, and enabling a sufficient definition for the accurate determination of the rotation of the stethoscope head with respect to the subjects' body and/or electrical axis of the heart .

The physical placement of this module with respect to the electronic module of measurement terminals (401) is also particularly advantageous in the invention. Although several other configurations are admissible in the context of the invention, the placement of this module directly in the stethoscope head, and consequently near the point of interface with the subject body, greatly minimizes the appearance of misleading or parasite signals.

The optional electronic module of PCG signal transduction and conditioning (405) performs the filtering and amplification of the signal obtained from a piezoelectric element, producing a more suitable representation of the physical quantity. The filtering type is band pass, having the typical passing band between 10 and 4000Hz, which, as common in these devices, is prone to parasite signals such as motion artifacts, radio frequency interference, and external ambient noise, among others. In our approach, the electronic module of PCG signal transduction and conditioning (405) comprises an amplifier with gain between 2 and 100, allowing the increase in the definition of the collected signal (in dB) , making the tenuous PCG signals have a sufficient definition for the cardiopathy detection support method to operate.

The physical placement of this module with respect to the electronic module of measurement terminals (401) is also particularly advantageous in the invention. Although several other configurations are admissible in the context of the invention, the placement of this module in the stethoscope head greatly minimizes the attenuation of the signals resulting from the integration of the remaining electronic modules previously described.

The electronic module of analogue-to-digital conversion (406), which transforms the conditioned electrical quantities produced by the electronic modules of ECG transduction and signal conditioning with virtual ground (402), fNIRS transduction and signal conditioning (403), IMU transduction and signal conditioning (404), and, optionally, PCG transduction and signal conditioning (403) into a digital representation manageable in the computational device (409), integrates a multi-channel quantization element and an analogue-to-digital converter. The quantization element is a component that maps the voltage or current to a set of bits (also known as resolution) , which in the case of the present invention is comprehended between 8 and 64 bits. The analogue- to-digital converter is a component that, at regular and pre defined time intervals, collects a sample, which is then quantized. In the case of the present invention, the frequency at which the samples are collected (sampling rate) can range between 250Hz and 40kHz, which in samples collected per unit of time corresponds respectively to 250 and 40000 samples per second .

Either intrinsically or through an additional auxiliary signal, the electronic module of analogue-to-digital conversion (406) also comprises the means for synchronization of all or part of the different (independent) signals collected by the electronic modules of ECG transduction and signal conditioning with virtual ground (402), fNIRS transduction and signal conditioning (403), IMU transduction and signal conditioning (404), and, optionally, PCG transduction and signal conditioning (403) .

The electronic module of signal transmission (407) is capable of sending the signals collected by the electronic modules of ECG transduction and signal conditioning with virtual ground (402), fNIRS transduction and signal conditioning (403), IMU transduction and signal conditioning (404), and, optionally, PCG transduction and signal conditioning (403), to the computational unit (409) using several methods. In this domain, the present invention is particularly advantageous since it can use a wireless channel using existing protocols such as Bluetooth, Wi-Fi, ZigBee or ANT, although other protocols can also be admissible.

Alternatively, the transmission can also be performed in a cabled manner, which in the present invention is also advantageous since it can be performed through conventional interfaces, such as USB, COM/RS232, GPIO pins, tracks in a printed circuit board, direct connection to the Rx/Tx pins on a micro controller, and others.

As a whole, the embodiment of the device is such that the sensory unit (408) and the computational unit (409) are integrated in one another. For example, we consider a preferred embodiment of the invention to be a stethoscope, which integrates the sensory unit (408) and the computational unit (409) directly in a single device, and implements a method which makes it behave in a different way, processing the data collected by the sensory unit (408) in order to produce an output to support cardiopathy assessment of the subject under examination .

In any case, by reasons related with the convenience of application and use of the device, other configurations may be more suitable. As such, other embodiments of the sensory unit (408) are also admissible, in which the sensory unit (408) and the computational unit (409) are detached from one another, but where the electronic module of signal transmission (407) from the sensory unit (408) ensures the communication between both. For example, we consider a preferential embodiment of this invention to be the combination of a stethoscope that integrates the sensory unit (408) and transmits the signals through a wireless interface to a tablet device, which in this case serves also as the computational unit (409) of the device.

The previously described examples should not limit the scope of the invention, in particular in what concerns the computational unit (409), since this can assume different formats, which include dedicated hardware, specifically created for the implementation of the cardiopathy assessment method, but that can also take advantage of already existing hardware such as portable electronic devices, portable computers, desktop computers, a computer screen, or any other device designed for human-machine or machine-machine interaction .

The cardiopathy assessment method can resort to information stored in a database of known pathologies. Data collection for this database is initially performed using the sensory unit (408) . The computational unit (409) either integrates a database of known pathologies, or communicates with a central server that stores that information remotely. For cardiopathy assessment, in particular, about supporting the decision process, there is a method in charge of handling the data, which collects the information transmitted by the sensory unit (408), and produces information to support the decision made by the medical practitioner.

The cardiopathy assessment method used in the present invention is particularly advantageous given that it can produce a recommendation on the identification of a pathology as an extension of the standard auscultation process that is, guaranteeing that the cardiopathy assessment occurs during the time in which the subject is monitored with the device. The method applies a set of pattern recognition and knowledge discovery algorithms, which fuse the signals collected by the sensory unit (408), in raw form or as an alternative representation derived from representative features extracted from them, and that matches the resulting information with patterns previously stored in the database.

This process is composed by a first stage in which the signal received from the sensory unit (408) is pre-processed, a second stage where the representative features are extracted, and a final stage of classification, where a decision is produced. In the pre-processing stage, an additional digital filtering step is implemented which complements those performed in the sensory unit (408) . The representative features extraction stage performs the segmentation of the ECG waveform and its different complexes (P-QRS-T) , or, in alternative, just a few complexes are segmented for improved efficiency (RS-T) , the segmentation of the fNIRS waveforms and their different complexes, and the segmentation of the PCG waveform and its different complexes (SI, S2) . Furthermore, it integrates the IMU signals, which is particularly advantageous in this invention, since it allows a more accurate detection of the events of interest in a way that is independent of the positioning of the stethoscope head with respect to the subjects' body and/or electrical axis of the heart.

Representative information about the complexes can also be extracted for each signal, such as latencies and amplitudes (PQ segment, ST segment, Sll, S12, S21, among others); furthermore, the average of several ECG heartbeat waveforms, fNIRS waveforms, PCG waveforms, or of the extracted information can also be used. These are also particularly advantageous properties of the present invention.

The classification stage compares the extracted representative information with the data stored in the database, or uses a model stored in the same, to recognize a cardiopathy by means of a convolutional neural network (CNN) , Support Vector Machines (SVM) , or, alternatively, a clustering method, a Bayesian statistical classification, or, a nearest neighbour (k-NN) approach with Euclidean distance as similarity metric. Still, other classification methods are admissible in the context of the present invention. Finally, a recommendation about the cardiopathy of the user is produced in the computational unit (409), together with a representation of the acquired signals and/or extracted representative information .

The result produced by the computational unit (409) can have different technical effects, which include but are not limited to: the identification of the user of the device, the verification of the identity of the user of the device, recommendation of abnormalities detected in the signals, presentation of relevant information to support cardiopathy assessment, or a summary report of the extracted representative information. The device is particularly advantageous for the purpose for which it is designed, since it allows the simultaneous acquisition of multiple parameters, processing of said signals with the purpose of supporting the cardiopathy assessment process, and the connection or relaying of control signals to other devices and accessories to generate a technical effect as a result of the previously described functions . The invention can be better understood through the analysis of the corresponding drawings, some of which illustrate preferential embodiments.

Figure 1 illustrates the typical representation of a PCG signal during a series of heartbeat cycles. Part of the representative information of the signal is: heart sound segmentation into cardiac cycles; segmentation of the first heart sound (SI); segmentation of the second heart sound ( S2 ) ; and, optionally segmentation of the third and fourth heart sounds (S3 and S4, respectively) . In a complete heart cycle, four phases can be identified, from which two sounds can be heard. Firstly, there is the closure of the mitral and tricuspid valves (first sound - SI), then the systolic period, following the closure of the aortic and pulmonary valves (second sound - S2) and finally the diastolic period. Also, Si's frequency is usually lower than S2's, and its duration longer.

The PCG signal can also be characterized by the raw data itself as collected by the sensory unit (408), or by representative latency and amplitude information extracted from notable points within the raw data (e.g. the elapsed time between the SI and S2 instants - S12 -, between consecutive SI instants - Sll -, between the S2 instant and the subsequent SI instant - S21 -, etc.), by a combination of these, or also by other types of parameters or alternative representations (e.g. Fast Fourier Transform - FFT -, Discrete Cosine Transform - DCT - or Wavelets) .

Figure 2 illustrates the typical representation of an ECG signal during a heartbeat cycle. Part of the representative information of the signal is: the P instant, which corresponds to the activation of the sinoatrial node (the natural pacemaker of the body which triggers the heartbeat); the QRS instants, which correspond to the contraction of the heart due to the depolarization of the muscular fibres; and the T instant, which corresponds to the relaxation of the cardiac muscle by effect of the muscle fibres repolarization.

The ECG signal can also be characterized by the raw data itself as collected by the sensory unit (408), or by representative latency and amplitude information extracted from notable points within the raw data (e.g. the elapsed time between the P and R instants - PR -, between the S and T instants - ST -, etc.), by a combination of both, or also by other types of parameters or alternative representations (e.g. Fast Fourier Transform - FFT -, Discrete Cosine Transform - DCT - or Wavelets) .

Figure 3 illustrates the typical representation of an fNIRS signal during a series of heartbeat cycles for the red and infrared components. Part of the representative information of the signal is: the peak-to-peak value; the amplitude ratio between both light components; the regularity of the waveform, in particular the dichroitic notch; and the baseline wandering. The fNIRS signal can also be characterized by the raw data itself as collected by the sensory unit (408), or by representative latency and amplitude information extracted from notable points within the raw data, by a combination of both, or also by other types of parameters or alternative representations (e.g. Fast Fourier Transform - FFT -, Discrete Cosine Transform - DCT - or Wavelets) .

Figure 4 illustrates the block diagram, depicting the main modules of the device to support the cardiopathies assessment based on the acquisition and fusion PCG, ECG, and fNIRS signals. Depending on the preferred embodiment, the signal measured from the electronic module of ECG measurement terminals (401), feeds the electronic module of transduction and signal conditioning with virtual ground (402) that performs the filtering and amplification of the ECG signals, the electronic module of fNIRS transduction and signal conditioning (403) that performs the filtering and amplification of the fNIRS signals, and, optionally, the electronic module of PCG transduction and signal conditioning (405) that performs the filtering and amplification of the PCG signals. The electronic module of ECG measurement terminals (401) also includes the electronic module of IMU transduction and signal conditioning (404) that performs the filtering and amplification of the IMU signals. In turn, the outputs of the aforementioned electronic modules are transformed by the electronic module of analogue-to-digital conversion (406) into a representation manageable in the computational unit (409) . The signals are then passed by an electronic module of signal transmission (407) and sent to the computational unit (409), which produces a result about the cardiopathy assessment. The electronic module of measurement terminals (401) can be particularized as the diaphragm of a stethoscope head (503), or as an external attachment to an existing stethoscope head (703) or (803) .

Figure 5 illustrates a schematic view of one of the preferential embodiments of the present invention where the cardiopathy assessment is performed directly in the stethoscope, in which the sensory unit (408) is integrated in the stethoscope head, in a setup that does not require external devices. The electronic module of measurement terminals (401) is an arrangement of sensors on the stethoscope diaphragm (503) . The signals are measured from any combination of the available elements, and the sensory unit (408) is integrated in the stethoscope head (502) . In this case, the transmission can be performed through tracks on a printed circuit board that allows the signals to reach the central processing unit of the stethoscope (503), which is in charge of the process performed by the computational unit (409) (pre-processing, extraction of the representative information and cardiopathy assessment) . In this scenario, a graphical representation of the signals and/or the decision produced by the cardiopathies assessment system can be presented in the central processing unit of the stethoscope head (501) .

Figure 6 illustrates a schematic view of another preferential embodiment of the present invention, in which the sensory unit (408) integrated in the stethoscope head (502) has an electronic module of signal transmission (407) that enables wireless data transmission to a tablet computer (601), which corresponds to the computational unit (409) . In this configuration, there is no direct contact between the sensory unit (408) and the computational unit (409); there is only the electronic module of measurement terminals (401), which is enclosed inside the structure of the stethoscope head, enabling the acquisition of the signals of interest. When the electronic module of measurement terminals (401) is placed on the subjects' body, the device will measure the signals of interest and transmit them for cardiopathy assessment. Using the acquired data, a graphical representation of the signals or of the cardiopathy assessment results can be presented in the graphical representation screen of a tablet computer (602) that the computational unit (409) has for such purpose.

Figures 7 and 8 illustrate a schematic view of other preferred embodiments of the present invention, in which the sensory unit (408) is integrated in an accessory that can be attached to a standard stethoscope head. The electronic module of measurement terminals (401) is integrated in the base of the accessory (703) or (803), which are elements of the sensory unit (408) . The signals are measured through any combination of the available sensors, which are integrated in the sides of the accessory (702) or (802) . Regardless of the configuration of the sensory unit (408) it acquires the signals using the electronic module of measurement terminals (703) or (803), amplifies the signal, and performs its conditioning and analogue-to-digital conversion in order to allow its transmission to the computational unit (409) . The transmission can be performed through a wireless channel, through a USB bus, or through any other type of connection, to any other subsystem that can perform the tasks of the computational unit (409) (pre-processing, extraction of the representative information and cardiopathy assessment) .

Figure 9 illustrates a schematic view of a possible sensor arrangement in the stethoscope diaphragm (503) or base of the accessory (703) or (803) used in the present invention, in which the electronic module of measurement terminals (401) incorporates at least two conductive electrodes (901), not necessarily composed of metallic material (i.e. conductive coatings, films, conductive tapes or other materials that eliminate the need to use any kind of metallic element and conductive gel or paste) , with protuberances designed to go through natural body barriers such as androgenic hair, providing an adequate contact with the body surface to enable ECG signal acquisition. In this arrangement, the electronic module of measurement terminals (401) also integrates four light emitter/receiver pairs in the visible and invisible light range (902) and a piezoelectric element to capture the cardiac sounds ( 903 ) .

Examples

Example 1. Sensory unit enclosed on a stethoscope head- computational unit

In one of the preferred embodiments of the present invention, the sensory unit (408) is enclosed on a stethoscope head, which also works as the computational unit (409) .

In this embodiment, the stethoscope head has a diaphragm that integrates the electronic module of measurement terminals (503), incorporating at least two conductive electrodes (901), not necessarily composed of metallic material (i.e. conductive coatings, films, conductive tapes or other materials that eliminate the need to use any kind of metallic element and conductive gel or paste) , with protuberances designed to go through natural body barriers such as androgenic hair, integrating four light emitter/receiver pairs in the visible and invisible light range (902) and, optionally integrating a piezoelectric element to capture the cardiac sounds (903) . These are connected to the electronic module of ECG transduction and signal conditioning with virtual ground (402), to the electronic module of fNIRS transduction and signal conditioning (403), and, optionally to the electronic module of PCG transduction and signal conditioning (407) . The electronic module of signal transmission (407) between the sensory unit (408) and the computational unit (409) transmits the signal through the motherboard of the stethoscope head, using tracks in the printed circuit board of the device. Example 2. Sensory unit integrated in a stethoscope head- computational unit with a central processing unit

In another preferred embodiment of the present invention, the sensory unit (408) is integrated in the stethoscope head, the computational unit (409) being the central processing unit of a tablet computer. In this embodiment the sensory unit (408) comprises an electronic module of signal transmission (407) with wireless connectivity (via Bluetooth, Wi-Fi, ZigBee, ANT or any other protocol that allows wire-free communication) , by means of which the signals are transmitted to the tablet computer (601), where they are processed and shown together with the result of the cardiopathy assessment process in the graphical representation screen of the tablet computer (602) .

In another preferred embodiment of the present invention, the sensory unit (408) is integrated in an external accessory, in which case the computational unit (409) is either the processing unit on the stethoscope head or the processing unit of a tablet computer. In this embodiment, the sensory unit (408) has a base that integrates the electronic module of measurement terminals (401), allowing the ECG and fNIRS to be acquired with the accessory applied to a standard stethoscope head, without significantly interfering with the acquisition of PCG signals. The electronic module for signal transmission (407) has a module for cabled or wireless communication (via Bluetooth, Wi-Fi, ZigBee, ANT or any other protocol that allows wire-free communication) .

In any of the embodiments previously described, the computational unit (409) executes a set of pattern recognition algorithms that match the acquired signals and related representative information, to the patterns previously stored for the monitored users. For illustrative purposes, in the scope of the described embodiments, the cardiopathy assessment is performed through a convolutional neural network (CNN) , support vector machines (SVM) , or Bayesian inference, although other approaches are also possible.

Without loss of generality due to the fact that a detailed description of the invention was disclosed, its preferred embodiments should not constitute a limitation to the overreach of the invention. In this sense, not only other variations of the preferred embodiments are admissible, but also all other embodiments that share the claimed characteristics are considered to belong to the scope of the present invention.

Claims

1. A medical device for cardiopathy assessment characterized by being based in electrocardiographic, functional near infrared spectroscopy, phonocardiographic and inertial signals, comprising a sensory unit (408) that includes an electronic module of measurement terminals (401), an electronic module of ECG transduction and signal conditioning with virtual ground (402), an electronic module of fNIRS transduction and signal conditioning (403), an electronic module of IMU transduction and signal conditioning with virtual ground (404), an electronic module of PCG transduction and signal conditioning with virtual ground (405), an electronic module for analogue- to-digital conversion (406), an electronic module for signal transmission (407), a computational unit (409) comprising any type of electronic device, wherein:

- the electronic module of measurement terminals (401), comprises at least two non-metallic conductive electrodes, with protuberances designed to go through natural body barriers such as androgenic hair providing an adequate contact with the body surface to enable ECG signal acquisition, for the measurement of the electrical potential differential;

- it includes a virtual reference in the electronic module of ECG transduction and signal conditioning (402) ;

- the electronic module of measurement terminals (401), comprises at least one light emitter / receiver pairs in the visible and invisible light range;

- the electronic module of measurement terminals (401), comprises at least one piezoelectric element; - the electronic module of ECG transduction and signal conditioning with virtual ground (402), includes a noise filter;

- the electronic module of fNIRS transduction and signal conditioning (403), includes a noise filter;

- the electronic module of IMU transduction and signal conditioning (404), includes a noise filter;

- the electronic module of PCG transduction and signal conditioning (405), includes a noise filter;

- the computational unit (409) includes a method for correcting the signals obtained from the electronic module of ECG transduction and signal conditioning with virtual ground (402), electronic module for fNIRS transduction and signal conditioning (403), and/or electronic module of PCG transduction and signal conditioning (405), based on the signals from the electronic module of IMU transduction and signal conditioning (404) .

- the computational unit (409) includes a method for cardiopathy assessment.

2. A medical device according to claim 1, characterized by:

- the sensory unit (408) is integrated in the head of a standard stethoscope (502);

- the computational unit (409) is the central processing unit of the stethoscope (501);

- the electronic module of measurement terminals (401) integrated in the diaphragm of the stethoscope (503) is embodied by non-metallic conductive elements;

- the electronic module for signal transmission (407) includes a method for direct communication with the central processing unit of the stethoscope.

3. A medical device according to claim 1, characterized by:

- the sensory unit (408) is integrated in the head of a standard stethoscope (502) ;

- the computational unit (409) is the central processing unit of a tablet computer (601) ;

- the electronic module for signal transmission (407) includes a method for wireless communication with the central processing unit of the tablet computer (601) .

4. A medical device according to claim 1, characterized by:

- the sensory unit (408) is integrated in an accessory that can be attached to a standard stethoscope;

- the computational unit (409) is the central processing unit of a tablet computer (601) and the graphical representation is the screen of the tablet computer (602) ;

- the electronic module of measurement terminals (401) integrated in the base of the accessory (703) or (803) is embodied by non-metallic conductive elements (503) ;

- the electronic module for signal transmission (407) includes a method for direct communication with the central processing unit of the stethoscope (502) .

- the electronic module for signal transmission (404) includes a method for wireless communication with the central processing unit of a tablet computer (601) .

5. A medical device according to any of the claims 1 to 4, characterized by the electronic module of measurement terminals (401) comprises non-metallic elements with conductive coatings, films or adhesives.

6. A medical device according to any of the claims 1 to 5, characterized by the electronic module of measurement terminals (401) is other non-metallic materials, capacitive sensors or piezoelectric sensors.

7. A medical device according to any of the claims 1 to 6, characterized by the electronic module of the measurement terminals (401) of the sensory unit (408) is integrated in the referred sensory unit (408) .

8. A medical device according to claim 7, characterized by the electronic module of the measurement terminals (401) of the sensory unit (408) is connected to the remaining modules of the referred sensory unit (408) .

9. A medical device according to claim 8, characterized by the sensory unit (408) is separated from the computational unit (409) .

10. Method for cardiopathy assessment from electrocardiographic signals, functional near infrared spectroscopy signals, inertial signals, and phonocardiographic signals, using the device defined in claims 1 to 9, characterized in that it comprises the following steps:

a) acquisition of the ECG signal through the electronic module of measurement terminals (401);

b) transduction and signal conditioning with virtual ground that measures the signal using one or more measurement terminals, filters and amplifies the resulting signal through the electronic module of ECG transduction and signal conditioning with virtual ground (402) ;

c) acquisition of the fNIRS signal through the electronic module of measurement terminals (401);

d) transduction and signal conditioning that measures the signal using one or more red and infrared light emitter / receiver pairs, filters and amplifies the resulting signal through the electronic module of fNIRS transduction and signal conditioning (403);

e) acquisition of the IMU signal through the sensory unit (408) ;

f) transduction and signal conditioning that measures the signal using one or more accelerometer, gyroscope and magnetometer sensors, each with three axis, filters and amplifies the resulting signals through the electronic module of IMU transduction and signal conditioning (404);

g) acquisition of the PCG signal through the electronic module of measurement terminals (401);

h) transduction and signal conditioning that measures the signal using one or more piezoelectric sensors, filters and amplifies the resulting signal through the electronic module of PCG transduction and signal conditioning (405);

i) signal conversion through the use of the electronic module of analogue-to-digital signal conversion (406) that integrates a quantization element and an analogue-to-digital converter, that transforms the physical quantities corresponding to the electrocardiographic signal into a digital representation;

j ) transmission of the signals through the electronic module of signal transmission (407) that sends the signals acquired by the sensory unit (408) to the computational unit (409);

k) computational unit (409) that uses the signals generated by the sensory unit (408), processes those signals and extracts representative information related with the cardiovascular system of the monitored subject;

l) recording of the representative information of the cardiovascular system of the monitored subject in a database that is integrated or not in the computational unit (409) ;

m) classification of the representative information of the cardiovascular system of the monitored subject; n) recommendation on the cardiopathy assessment in the computational unit (409) .