Compact mobile three-lead cardiac monitoring device

Abstract

To solve a problem that there is necessity for a handheld ECG that can diagnose a wide-range heart condition while the handheld ECG is compact and easy to be carried in a pocket or a wallet.SOLUTION: Provided is a compact mobile three-lead cardiac monitoring device for remote detection and / or diagnosis of a cardiac event (e.g., acute myocardial infarction). An apparatus may include two integrated hand electrodes and two chest electrodes disposed on two pivotable arms that are capable of retracting in compartments, enabling a compact size when the device is not used. Also described herein are systems including these devices and methods of using them.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This patent application claims priority to U.S. Provisional Patent Application No. 62,847,308, filed May 13, 2019, entitled "COMPACT MOBILE THREE-LEAD CARDIAC MONITORING DEVICE."

[0002] (Incorporated by reference) All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

[0003] The methods and devices (e.g., systems, apparatus, etc.) described herein generally relate to electrocardiography. Described herein are devices and systems, and methods of using same, that include small, handheld electrocardiogram (ECG) devices with retractable electrodes. In addition to recording ECG signals, these devices may process and transmit ECG data to a handheld processor (e.g., a smartphone) and / or transmit the ECG data to a remote computer server for automated analysis and generation of diagnostic information that is sent back to the patient and / or to a medical professional. [Background technology]

[0004] Handheld ECG devices have been proposed. Such devices can be used by a patient (or medical professional) to record an ECG. However, to date, despite the potential advantages of such handheld devices, none have been widely adopted. This is due, in part, to the relatively large size and weight of proposed devices and complex form factors, which may include a handle and / or several cables. Additionally, many such proposed devices have components that protrude from the device's exterior when the device is not in use. Therefore, there is a need for a handheld ECG device that is capable of diagnosing a wide range of cardiac conditions, while being compact and easy to carry in a pocket or purse. Summary of the Invention [Problem to be solved by the invention]

[0005] Described herein are devices and methods that can address these problems. [Means for solving the problem]

[0006] The present invention relates to methods and devices, including small, lightweight handheld ECG devices that can be easily carried and handled, including slipping into a pocket or purse. These devices are also ergonomic and easy to use, and are capable of detecting a variety of cardiac conditions.

[0007] For example, described herein are credit card-like three-lead mobile cardiac monitoring devices for automatic recording of ECGs. These devices are compact, for example, having a maximum thickness in a stored configuration of 2 cm or less (e.g., 1.9 cm or less, 1.8 cm or less, 1.7 cm or less, 1.6 cm or less, 1.5 cm or less, 1.4 cm or less, 1.3 cm or less, 1.2 cm or less, 1.1 cm or less, 1.0 cm or less, etc., including between 0.2 and 2.2 cm, between 0.2 and 2 cm, etc.). These devices are easy to handle and lightweight, easily portable when not in use, and effective in detecting and diagnosing various cardiac conditions.

[0008] Thus, described herein are small, handheld ECG devices for recording and analyzing a patient's ECG without the use of cables. In some variations, they are credit card-shaped (e.g., relatively thin and having a small diameter, e.g., a maximum diameter of 12 cm or less (e.g., 11 cm or less, 10 cm or less, 9 cm or less, 8 cm or less, etc.)). These devices are highly mobile and can be configured for three-lead cardiac monitoring. The devices can include two electrodes for contacting the patient's chest and two electrodes for contacting the patient's fingers. The finger electrodes can be integrated into the front and / or sides of the device.

[0009] For example, four electrodes may be provided on the front surface and on two pivoting arms so that when the device is in the active position it can be held by a user's hands in a predetermined orientation and record orthogonal three-lead cardiac signals when held against the user's chest. An example of orthogonal lead recording is described in WO 2016 / 164888, which is incorporated herein by reference in its entirety.

[0010] In some variations, the device may be used in conjunction with or as part of a system configured for the automatic or semi-automatic detection and diagnosis of acute myocardial infarction (AMI), atrial fibrillation, or other cardiac disease by acquiring substantially orthogonal leads from four integral electrodes that can be operated by a patient experiencing symptoms related to an ongoing cardiac event and used to create cardiac vectors that can be further used, for example, as part of a difference vector analysis of cardiac vectors to detect one or more cardiac events. The cardiac difference vectors may be used, along with additional information including risk factor information and current symptom information, to further define the patient's emergency status, for example, to determine or confirm that the patient is experiencing a cardiac event.

[0011] Three orthogonal leads can be formed by using various electrode configurations with or without a centrally located resistive network, with the resulting three leads generally being non-coplanar and as close to orthogonal as possible.

[0012] In some variations, the device (system, apparatus, etc.) may perform a first set of reference recordings from three orthogonal leads, which may be stored in memory (e.g., resistors). During diagnostic recordings, a second set of three orthogonal leads may be acquired, and a difference signal between the two sets may be determined. Cardiographic signals, represented by parameters of the ECG reference recordings, diagnostic recordings, and difference signal, may be transmitted to an internal processor and / or wirelessly transmitted to a remote processor for processing. The device may also be configured to communicate diagnostic information to the patient. Received diagnostic information may be presented to the user in the form of distinctive sounds, voice, graphics, or text.

[0013] For example, the device may include a plate-like housing having a front and / or back surface. The housing may have a size and shape similar to a typical credit card. The housing may include two pivoting arms disposed on either side thereof, each arm including an electrode capable of acquiring signals related to the patient's chest. The arms may be stored in respective compartments on the housing when not in use, e.g., during transport, such that they fit flush with the outer surface of the housing (e.g., in a compact configuration).

[0014] Additionally, the arms may include locking means for locking the arms to the housing when held in the retracted position such that the arms are spring-biased to lock relative to the housing. The arms may include a bias (e.g., elastic, spring, etc.) to spring-bias the arms for release from the retracted position. Alternatively, the arms may be biased to be held in a folded configuration. The bias may be released when the arms are deployed. The arms may be locked in a folded configuration (and biased to expand when unlocked) and / or locked in an extended configuration (and in some variations, biased to fold into a compact configuration when unlocked). For example, such a torsion spring may be provided in association with each of the arms, such that an end portion of each torsion spring is supported by the arm and the housing, respectively.

[0015] The pivoting arms are compact when retracted into their respective compartments. When deployed, the arms extend into an active position forming an angle therebetween, thus allowing them to conform to the patient's chest morphology and providing good contact between the associated chest electrodes and the patient's skin. The distance between the chest electrodes in the deployed (e.g., active) position can be greater than 10 cm. In some variations, the arms and associated electrodes may extend beyond the edge of the housing in the deployed configuration.

[0016] In some variations, the device may include two hand electrodes disposed on the front and / or sides of the housing. For example, these two electrodes may be disposed on the front of the housing so that the patient's fingers rest on the two electrodes when the chest electrodes are in place on the patient's chest. This advantageously allows the patient to fully grasp and hold the device securely for ECG recording.

[0017] In some variations, these two "hand" electrodes are located on corresponding chamfers on the front longitudinal edge of the housing, allowing easy access by the patient's fingers along with the pressure needed to hold the housing to the chest. The hand electrodes are offset relative to the horizontal centerline of the front surface so that they are closer to the patient's left arm during recording, preventing the patient from switching their fingers between the left and right hands.

[0018] In some variations, the hand electrodes are disposed in a recessed portion in the front of the housing, allowing the hand electrodes to fit flush with the front. In some variations, the device has two finger electrodes and two chest electrodes, plus a ground electrode disposed in the front of the housing to be pressed by the fingers, similar to the hand recording electrodes.

[0019] For example, described herein is a three-lead mobile cardiac monitoring device (e.g., a "compact" device) having a first compact, non-deployed configuration and a second deployed configuration. The device includes a housing having a front and a back, two chest electrodes, two finger electrodes, and two retractable arms pivotally attached to the housing at opposite ends, the two finger electrodes disposed on the front or leading edge of the housing and the two chest electrodes disposed on the retractable arms, which retract flush with the back in the non-deployed configuration and extend at an angle to the back in the deployed configuration.

[0020] Also described herein are methods of using these three-lead mobile cardiac monitoring devices having a first, non-deployed configuration and a second, deployed configuration as described herein. For example, described herein is a method for automatically assessing a patient's risk of an acute cardiac event, the method including receiving risk assessment information from the patient including risk factors, the risk assessment information being received by a processor; storing a pre-existing risk score based on the risk assessment information; receiving a sample electrocardiogram (ECG) from the patient, the sample ECG being automatically recorded by the patient using the three-lead mobile cardiac monitoring device having the first, non-deployed configuration and the second, deployed configuration; receiving a current symptom indication from the patient; determining, in the processor, an ECG risk score from the sample ECG and the reference ECG and a chest pain risk score based on the current symptom indication; determining a post-test risk score using the ECG risk score, the pre-existing risk score, and the chest pain risk score; and presenting a diagnostic report and patient action instructions to the patient based on the post-test risk score.

[0021] Any of these methods may include deploying a three-lead mobile cardiac monitoring device from a first, compact, undeployed configuration to a second, deployed configuration. For example, deploying the device may include unlocking the legs so that they automatically extend from a storage compartment. Deploying may include holding the legs against the chest. The electrode and / or leg configurations described herein may provide enhanced contact, comfort, and accuracy. The electrodes may be adapted to accommodate this, while the body of the device is held away from the chest.

[0022] These methods include receiving a baseline ECG from the patient at a processor at least 24 hours prior to receiving the sample ECG, with the patient obtaining the baseline ECG using a handheld device. The risk factors may include age, total cholesterol, HDL, systolic blood pressure, diabetes mellitus status, and current smoking status. In some variations, the existing risk score based on the risk assessment information includes a weighted sum of the risk factors calculated.

[0023] Receiving the sample ECG includes the patient using a three-lead mobile cardiac monitoring device having a first, non-deployed configuration and a second, deployed configuration, the handheld device having at least four electrodes for acquiring three substantially orthogonal leads. Receiving the current symptom indication may include selecting the current symptom indication from a list of pre-defined symptoms selectable on the handheld device. In any of these methods, selecting may include selecting the current symptom indication from a user interface of the handheld device. Determining the ECG risk score may include indicating a risk that is high (H), medium (I), or low (L). Determining the chest pain risk score may include indicating a risk that is high (H), medium (I), or low (L). For example, determining the post-test risk score may include applying a lookup table indexed by the ECG risk score, the chest pain risk score, and the existing risk score. The steps of receiving the sample ECG and the current symptom indication may be repeated prior to determining the ECG risk score. The novel features of the invention are set forth with particularity in the following claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 shows a front axonometric view of the device with the arms in the deployed position when the device is ready for use for ECG recording. [Figure 2]1 shows a front axonometric view of the device in a transport position with the arms retracted into compartments in the housing, as when the device is not in operation. [Figure 3] FIG. 1 is a rear axonometric view of the device with the arms in the retracted position. [Figure 4] FIG. 10 is a detail view showing an axonometric view of the arms and compartments from the rear in the deployed position. [Figure 5] 5 shows a longitudinal cross-sectional axonometric view of FIG. 4. [Figure 6A] ~ [Figure 6B] 1 illustrates a prototype signal acquisition device for recording ECG. [Figure 7] 1 is an example of a patient using a signal collection device described herein. [Figure 8] 1 illustrates schematically the operation of a system using a signal acquisition device. [Figure 9A] 1 illustrates one variation of a schematic configuration of a diagnostic system for detecting cardiac disease, such as AMI, including a three-lead mobile cardiac monitoring device having a first compact, undeployed configuration and a second deployed configuration as described herein. [Figure 9B] 1 is another schematic diagram of a diagnostic system including a three-lead mobile cardiac monitoring device having a first compact, undeployed configuration and a second deployed configuration, the processor being remote from the handheld device. [Figure 10] FIG. 1 shows a simplified electrical method for determining the center point CP by connecting the electrodes on both hands through a simple resistive network comprising two resistors in a three-lead mobile cardiac monitoring device having a first compact non-deployed configuration and a second deployed configuration as described herein. [Figure 11A] A schematic configuration of three cardiac leads measured at the torso is shown, with one lead using the center point as the reference electrode. [Figure 11B] The electrical circuit of three cardiac leads is shown, with one lead using the center as the reference electrode. [Figure 11C] A schematic configuration of three cardiac leads measured at the torso is shown, with two leads using the center as the reference electrode. [Figure 11D]An electrical circuit of three cardiac leads, two of which use the center as the reference electrode. [Figure 11E] ~ [Figure 11G] Schematics of three possible configurations for measuring three leads among two chest electrodes and two hand electrodes are shown. [Figure 12] 1 shows a flowchart of a method for detecting AMI including a three-lead mobile cardiac monitoring device having a first compact, undeployed configuration and a second deployed configuration as described herein. [Figure 13] 1 is a table illustrating a parameter questionnaire list that may be used to estimate chest pain risk (CPR) as described herein. [Figure 14] 1 is a table illustrating an example of an AMI risk assessment method described herein. [Figure 15] 1 is a process flow illustrating one method of displaying risk and treatment advice to a patient as described herein. DETAILED DESCRIPTION OF THE INVENTION

[0025] Described herein are devices, including systems, that may include a compact (e.g., credit card-sized and shaped) three-lead mobile cardiac monitoring device for user placement on the chest. These devices may have four recording electrodes arranged to enable recording of three orthogonal ECG lead signals. These handheld devices may include two chest recording electrodes disposed on a swiveling and / or retractable arm hinged to the device's housing. The device may include two non-chest electrodes disposed on the front and / or sides (including chamfered sides) of the housing that may be used to collect cardiac signals from the fingers of the left and right hands. The device may also include an optional fifth electrode disposed on the front of the device that may be used as a ground electrode, resulting in a device with four recording electrodes and one ground electrode.

[0026] The devices described herein can be used, for example, in the case of a suspected cardiac event, for automatic remote diagnosis of cardiac conditions such as acute myocardial infarction (AMI), atrial fibrillation (AFiB), etc. The device is configured to measure three nearly orthogonal cardiac leads and store ECG recording components (e.g., electrodes, circuitry, controller) to record a patient's ECG signal along with most of the diagnostic information present in a conventional 12-lead ECG.

[0027] 1-4 illustrate an example of a device (a credit card-like handheld ECG device) described herein. The device may include a plate-like housing having a relatively small thickness compared to its length and width. The shape of the housing may be similar to that of a typical credit card, such that the base of the housing has a length and width approximately the same as a standard credit card, for example, between about 6 and 10 cm (e.g., between about 7 and 9 cm, between about 7.5 and 9 cm, between about 8.2 and 8.8 cm, about 8.6 cm), and a width of between about 4 cm and about 6.5 cm (e.g., between about 4.5 cm and about 6.5 cm, between about 5 and about 6 cm, between about 5.2 and 5.8 cm, such as about 5.4 cm). On average, the device housing may be thinner than 10 mm (e.g., about 8 mm or less, about 7 mm or less, about 6 mm or less, about 5 mm or less, about 4 mm or less, etc.).

[0028] In some variations, the housing 10 has a face 12 (e.g., a front face) with hand electrodes 14 for collecting signals from the patient's hands and two pivoting arms 16 hingedly connected to the housing 10, each arm carrying a chest electrode 18 for collecting signals from the patient's chest. The housing 10 can be made of plastic or metal.

[0029] Additionally, the housing 10 has a face 20 (e.g., a back face) that is recessed such that two opposing, generally columnar sections 22 are symmetrically positioned about a longitudinal centerline of the back face 20, each section 22 being formed adjacent a short edge 23 of the front face.

[0030] Each compartment has a bottom 24, two side walls 26, and a front wall 28. Unlike the side walls 26, which are perpendicular to the bottom 24, the front wall 28 is angled relative to the bottom 24, preferably at an angle of about 45 degrees, so that the compartments 22 flare outward from the bottom.

[0031] The bottom 24 of the compartment 22 defines two generally rectangular openings 30, 32 spaced apart along a longitudinal centerline. The proximal opening 30 is adjacent to the angled front wall 28, while the distal opening 32 is disposed at a short edge of the front surface 12 so as to have an open end. The distal ends of the side walls 26 are connected by a pin 34.

[0032] Compartment 22 can receive two pivoting arms 16 that are hinged to housing 10 via pins 34 disposed in compartment 22. At the tail portion 36, each arm has an integrally formed sleeve 38, with a coiled torsion spring 40 disposed in a slot 42 formed in arm 16 so as to be coaxial with sleeve 38. Torsion spring 40 includes two radially projecting tangs 44, 46. The first tang 44 mates with arm 16, and the second tang 46 mates with pin 34 within compartment 22. When the arms are retracted, first tang 44 moves angularly relative to second tang 46, creating a torsional bias for spring 40. Arms 16, along with spring 40, are attached to pins 34 with an interference fit. Each arm 16 is pivotable about its respective pin 34 so that the arms can be received in compartment 22 or deployed to form an angle of approximately 135 degrees therebetween.

[0033] The arms can be biased to open and / or close. For example, two spring plungers can be included inside the arms 16, perpendicular to the side surfaces 48. The plungers are slidably displaceable within associated cylinders so that the plunger tips 55 can point outward when the springs are de-energized. The plunger tips 55 can mate in a biased (e.g., spring-loaded) manner with corresponding sockets 56 formed in the side walls 26 of the compartment 22 to releasably lock and hold the arms 16 against the side walls 26 in the stored state by the spring force. Thus, in this example, the side walls 26 of the compartment 22 and the arms 16 are biased toward one another via a retaining spring. The spring force and the shape of the sockets 56 define the threshold force required to compress the springs 52 and release the plunger tips 55 from the sockets 56, thereby unlocking the arms 16. The cooperation of the tips 55 and sockets 56 ensures secure retention of the arms 16 when stored by a user in a pocket or purse.

[0034] The arm 16 can be accommodated in the compartment 22 by providing the arm 16 with a stepped pillar shape that complements the shape of the compartment 22 when the arm 16 is in the retracted position.

[0035] Each arm 16 includes a head portion 60 that is tapered at its distal end to form a recessed surface 61 for receiving a chest recording electrode 18. Surface 61 is sloped at an angle of approximately 45 degrees relative to an upper side 63 of head portion 60 so as to be parallel to the front and rear surfaces 12, 20 of the housing when arm 16 is in the deployed position, and parallel to the sloped front wall 28 of the compartment 22 when arm 16 is received in the stowed position. Arm 16 is stepped so that an upper side 68 of tail portion 36 is lower than an upper side 63 of head portion 60.

[0036] The head portion 60 of the arm 16 has a rectangular base shaped to be received in the rectangular opening 30 of the compartment 22 when the arm is retracted. At the same time, the top side 63 of the head portion 60 and the bottom side 72 of the arm 16 fit flush with the front and back sides 12 and 20 of the housing 10, respectively. In this way, the most compact size of the device is achieved when not in use.

[0037] Openings 30 in the bottom 24 of compartment 22 allow the patient's fingers access to arms 16 from the front, such that sufficient finger pressure is generated to unlock the arms by pressing on the upper side 63 of head portion 60 of arm 16 to move the arms 16 to the deployed position. The upper side 63 of head portion 60 of each arm is distinctively colored to allow operation even in low visibility conditions.

[0038] Recesses 73 are provided in the rear surface 20 such that each of the four semicircular recesses 73 adapted to receive the tip 55 of the plunger prior to mating with the socket 56 is positioned adjacent to and above the corresponding socket 56.

[0039] Two chest recording electrodes 18 disposed on the arms 16 are used to contact the patient's chest in the recording position. When the arms 16 are deployed in the active position, the two chest electrodes 18 can be spaced apart to span a distance greater than about 10 cm in the craniocaudal direction. The reason for this spacing is that it advantageously achieves a distance greater than the approximate diameter of the myocardium required to achieve maximum lead orthogonality.

[0040] Additionally, when the arms 16 are pivoted and moved to the deployed operating position, the angle between the arms conforms to the curvature of various body shapes, allowing for good contact with the patient's chest regardless of the patient's torso morphology.

[0041] According to some variations, in addition to the two chest electrodes, the device further includes two hand recording electrodes 14 disposed on chamfered portions 76 of the front long edge 78 of the device's front face 12 for easy finger access. The finger electrodes are preferably used to acquire cardiac signals from the fingers of the left and right hands by pressing them with the patient's thumbs.

[0042] According to an alternative embodiment, the device may include a third electrode disposed on the front surface of the device to be pressed with a finger and used as a ground electrode, the finger pressing on the non-chest electrode attached to the front surface 12 of the housing 10 generating sufficient pressure to hold the device against the chest.

[0043] The recording electrodes 14, 18 are made of a biocompatible plastic material with a contoured design that includes spherical protrusions that allow for effective gripping with the patient's chest and fingers, ensuring secure retention of the device in place. To operate, a user (e.g., patient) places and presses the device against their chest, e.g., with both hands, including their thumbs, so that each thumb contacts one hand electrode 14, thereby contacting the chest electrodes 18 to create intimate contact between the chest and the device. This can generate sufficient pressure to hold the device against the chest.

[0044] To prevent misplacement of the device, according to one embodiment, the hand electrodes 14 are offset relative to the lateral centerline of the anterior surface 12 to provide an asymmetrical electrode configuration. That is, during recording, the side of the anterior surface 12 on which the hand electrodes 14 are located is oriented toward the patient's head. In this way, the upper and lower sides of the device can be easily distinguished by the patient.

[0045] In the optimal recording position, the center of the device is placed just above the center of the heart so that the chest electrodes are approximately on the midclavicular line (a vertical line passing through the midpoint of the clavicle), and the lower chest electrodes are approximately at the level of the lower edge of the sternum.

[0046] Additionally, in alternative embodiments, the hand electrodes may be disposed on the front surface of the housing rather than on the chamfered front long edge for easier finger access and contact. Electrodes for recording ECG signals on the left and right arms by pressing with the fingers other than the thumbs on the left and right hands may be disposed in recessed portions of the front surface rather than on the tapered front long edge as described above for a flush fit with the front surface.

[0047] Active recording electrodes for recording ECG signals from the patient's chest are disposed on the pivoting arms of the device in the same manner as described above. At the recording position, the chest electrodes are pressed against the chest in a manner equivalent to that shown above.

[0048] In another alternative embodiment, an additional electrode that functions as a ground electrode may be disposed on the front of the housing so that it can be simultaneously contacted by one of the free fingers, as pressing the finger recording electrodes presses the device against the chest. The ground electrode functions to generate the additional force necessary to press the device against the chest and perform an accurate recording, and may preferably be made of a biocompatible plastic material with a contoured spherical protrusion that allows for effective grasping by the patient's fingers to ensure the device is held securely in place.

[0049] The optimal position for the handheld device on the chest is with the center of the device on the left side of the chest approximately above the center of the myocardium. In this position, the chest electrode is approximately on the midclavicular line, a vertical line passing through the midpoint of the clavicle, similar to the V4 electrode on a conventional ECG, and the lower chest electrode is approximately at the level of the lower edge of the sternum.

[0050] The handheld devices described herein are configured to be mechanically stable, allowing for good electrical contact with the chest, and to eliminate the possibility of finger contact switching. To prevent wasting recordings by turning the device upside down during a recording procedure, the top or front of the device may be clearly identified and / or configured (including markings) to be easily distinguishable by the patient, for example, by integrating an LED diode into the front upper surface of the device housing that indicates the current recording stage, so that the top side faces the patient's toes rather than facing the head. Additionally, since turning the device upside down can lead to recording errors, it is desirable for the top (head-facing) and bottom (toe-facing) of the device to be easily distinguishable.

[0051] In some variations, a four-electrode configuration without a ground electrode (e.g., two chest electrodes and two finger electrodes) is used. This configuration can provide acceptable 50-60 Hz electrical noise performance when a ground-free signal amplifier configuration is used. This recording electrode configuration can also meet the requirement of high orthogonality. The simplest approach to this requirement is to record signals in the three cardinal body directions: horizontal (left arm-right arm), sagittal (front-to-back), and craniocaudal (head-to-toe). For example, horizontal signals can be obtained by measuring leads between the left and right hands. Cranial-caudal signals can be obtained by measuring leads between two chest electrodes, provided that the distance between the chest electrodes is at least 5 cm, preferably greater than about 10 cm, to ensure a distance greater than the approximate diameter of the myocardium. In an ideal case, sagittal signals would be measured between the patient's back and chest, which is not possible due to the constraint of using only finger and chest electrodes. To overcome this, a simple resistive network is used to establish a midpoint (CP) near the electrical center of the heart. To record the leads in a roughly sagittal direction, two hand electrodes and two resistors are used to record the voltage at the lower chest electrode about the resulting midpoint (CP). The two resistors are either equal, approximately 5 kOhms (kΩ) each, or unequal, with the first resistor between the left-hand electrode and the CP being approximately 5 kOhms (kΩ) and the second resistor between the right-hand electrode and the CP being approximately 10 kOhms (kΩ). This asymmetry reflects the left-side location of the heart in the torso, thus shifting the CP to approximately the electrical center of the heart. This results in a roughly orthogonal three-lead system. Other lead configurations, with or without CPs, may also be used.

[0052] The handheld device is configured as a stand-alone device incorporating cardiac signal recording circuitry including an amplifier and AD converter for amplifying signals detected by the electrodes, data storage circuitry (e.g., memory) for storing recorded signals, communications circuitry operating on GSM, WWAN, or similar telecommunications standards for communication with a remote processor (e.g., PC computer, pad, smartphone, etc.), and circuitry (e.g., screen, speaker, etc.) for communicating diagnostic information to the user in the form of visual and / or audio output.

[0053] A handheld device equipped with a special electrode configuration is capable of recording orthogonal three-lead cardiac signals in an orientation-specific manner and transmitting these signals to a processor (e.g., a PC or other computing device). The remote processor can be configured to diagnose / detect AMI and transmit diagnostic information back to the handheld device.

[0054] Each user can be enrolled in the diagnostic system by performing an initial transmission of their own asymptomatic cardiac recording with three cardiac leads. This initial recording can be used as a reference recording for AMI detection in diagnostic recordings (which means further recordings of the same user's three cardiac leads). The availability of a reference cardiac recording can also provide a tool for automated AMI detection that can distinguish between old and new ST-segment elevation (STE) or equivalent parameters and other cardiac signal changes suggestive of AMI, with diagnostic accuracy comparable to that of human ECG interpretation.

[0055] The remote processor may be equipped with diagnostic software for processing the received cardiac signals to generate diagnostic information and for transmitting the information back to the handheld device for communication to the patient. The device may perform automatic detection of cardiac conditions based on a three-lead system, eliminating the need for a specialist to interpret the processed diagnostic information.

[0056] The signal processing and diagnostic software may also run on a processor (e.g., a microprocessor) integrated into the housing of the handheld device to process the recorded cardiac signals and generate diagnostic information. When diagnostic processing is performed by a remote processor, a backup version of the software running on the microprocessor may be integrated into the handheld device for use in situations where the user is in a zone outside of wireless network coverage.

[0057] The device may communicate with a remote processor via a communications integrated circuit. The remote processor may communicate with the handheld device via an integrated communications module. The generated diagnostic information may be transmitted to the device memory from the remote processor (e.g., a PC computer, server, etc.) via a commercial communications network. The handheld device may communicate the diagnostic information to the patient via a distinctive sound via a microphone that emits a distinctive sound or voice message, or in the form of graphic information via a display integrated into the device.

[0058] example The devices described herein may be referred to as signal acquisition devices. Figures 6A-6B illustrate a prototype of an exemplary signal (ECG) acquisition device shown in a compact configuration (Figure 6A) and a deployed configuration with chest electrodes deployed (Figure 6B).

[0059] In some variations, the device may be used as part of a subscription service (e.g., a recurring service for x$ / month) where the patient signs a subscription plan or is signed up for by a physician, insurer, etc. while exhibiting symptoms of a cardiac event and recording an ECG. The system may provide reports to the patient directly and / or to a physician who may contact the patient. The output (e.g., patient or physician report) may include advice (go to the ER, call a physician, etc.). In some variations, the report may include an analysis of the cardiac vector and / or an ECG representation (including a composite ECG generated from the cardiac vector / orthogonal leads) along with risk factors. In some variations, the report provides a high, low, medium (etc.) indication of the likelihood of a cardiac event.

[0060] Alternatively, reporting may be fully automated, with the system generating a score based on a differential comparison between an acutely measured cardiac vector (when the patient suspects a cardiac event) and a reference cardiac vector (e.g., measured from the patient when no cardiac event is observed on closer examination by the system). The system analysis engine generates the score and sends it directly to the patient, either to the handheld signal collection device and / or to a mobile device (e.g., a smartphone) associated with the handheld signal collection device.

[0061] Thus, any of the devices described herein may include software or firmware that is either part of the signal collection device and / or part of a mobile device (e.g., a smartphone) in communication with the signal collection device. For example, described herein is an application (e.g., an “app”) that may drive the processor of the signal collection device and / or mobile communication device and may operate the signal collection device to collect patient data (e.g., risk factors), subscribe to a patient, allow the patient to collect one or more ECGs using the signal collection device, collect user symptom data associated with the ECGs, and / or provide a user interface for reporting analysis results. The application may securely communicate between the signal collection device and a remote server (e.g., a cloud-based server) for analyzing and storing patient ECG data, risk factors, and other related data.

[0062] For example, in some variations, a patient may use an app to acquire an ECG using a signal collection device. The patient launches the app and selects a new recording (baseline or test / symptom ECG), and the app allows the user to retrieve the recording. In some variations, the signal collection device may wirelessly communicate (e.g., via a wireless personal area network, including any wireless technology, particularly Bluetooth®) with the mobile communication device running the app. Upon initialization, the app may locate and automatically activate (and subsequently deactivate) the signal collection device, and either the signal collection device or the app (or a combination of both) may detect skin contact and begin recording from the chest and finger electrodes. The recorded signals (from all three leads, including the virtual sagittal lead derived from the center point of the resistive network between the left and right hand electrodes and one of the chest electrodes, e.g., the lower chest electrode) may be processed by the signal collection device and / or application (e.g., a smartphone), including processing to ensure sufficiently low noise and quality of the collected data. The recorded signals may be stored in the signal collection device and / or mobile communication device during use and later transmitted to a remote server. The signal collection device may include a storage device and / or the signals may be stored on the patient's smartphone and then transmitted to a remote server (e.g., the cloud) for analysis and processing.

[0063] Generally, the analysis may include a baseline analysis. A baseline ECG (e.g., a baseline cardiac vector) may be obtained when the patient first subscribes to and / or purchases the device. The baseline signal may be carefully examined by the system. For example, the baseline signal may be examined to ensure it falls within some predetermined "normal" parameter range. For example, a patient's baseline signal may be determined by performing a difference vector analysis of the baseline cardiac vector determined from three orthogonal leads of a signal acquisition device. Multiple baseline measurements may be taken and averaged or the best one selected. If the baseline does not fall within expected parameters, for example, because it has an irregular cardiac vector for any reason (including a concurrent undetected cardiac event), the patient may be rejected as an unqualified candidate. The system may periodically prompt the user to provide an updated baseline signal.

[0064] In some variations, the application software may perform quality control (QC) checking (e.g., a QC agent, software agent, etc.) for signals that may indicate whether the reference cardiac vector is sufficient. This may occur in real time and may include signal quality checks that may occur on either or both the signal collection device and the mobile communication device (e.g., a smartphone) and / or on a remote server. The QC agent may seek signal clarity and / or may also verify that the patient is not having a heart attack. This may be part of a final level quality check.

[0065] The application software / firmware may also obtain risk factors from the patient. Advantageously, this may occur at the time of subscription. The patient may be presented with a series of questionnaires and / or have access to electronic medical records representing risk factors associated with cardiac conditions (e.g., heart attack, etc.). The information may include patient-specific information (age, gender, weight, height, ethnicity, cholesterol levels, blood pressure, etc.). The questionnaires may be ordered and weighted. A minimum amount of risk factor information may be permitted (e.g., age only, age and gender only, etc.). If the minimum information is not provided, the patient will not be permitted to subscribe.

[0066] As mentioned above, the application may prompt the patient to update their baseline periodically (e.g., weekly, bimonthly, monthly, etc.) by sending a message (SMS / text message) within the app or without the app (from a remote server).

[0067] In use, a patient may use the app to initiate an ECG recording for testing (e.g., when experiencing symptoms associated with a cardiac event or perceiving a risk for a cardiac event) or to update symptomatic or asymptomatic criteria, for example. The user may initially indicate which type of recording will be made. If the patient indicates symptoms, the app may expedite the ECG recording and analysis to provide a real-time response as quickly as possible. After the user starts the app and indicates through the user interface that they would like a symptomatic ECG analysis performed, the system may make a recording of three orthogonal leads that provide a cardiac vector (and may obtain two or more recordings using a QC agent). This recording may first be reviewed locally or remotely (e.g., by the smartphone / app at the signal collection device and / or a remote server) to determine whether the recent cardiac vector indicates that a cardiac event may be occurring. Based on the differential vector analysis of the cardiac vector (compared to the reference cardiac vector), and in some variations, in conjunction with recorded patient-specific risk factors, if the likelihood exceeds a cutoff threshold, the patient is immediately instructed, for example, through the app or by direct contact (e.g., by phone) to seek treatment. In some variations, a medical professional may be directly contacted. If the preliminary analysis score is below the threshold, the patient may be prompted to provide additional symptom information, such as location, duration, and / or pain intensity, pain type, pain acuity, etc. Symptom information is collected by the app and transmitted to a remote server, which combines this information with the patient risk factors and differential cardiac vector information to create a final score that is sent to the patient and / or medical professional. If the score exceeds the threshold, indicating a possible cardiac event, the patient may be instructed to seek immediate treatment and / or may be automatically contacted to perform medical intervention. If the score is within the intermediate range, the patient may be instructed to seek follow-up with a medical provider. If the score is within the low-probability range, the patient may also be notified. For intermediate or low scores, the patient may be instructed to take a follow-up interpretation over a predetermined amount of time (e.g., 10 minutes, 20 minutes, 30 minutes, etc.), which may be adjusted by the app.

[0068] Alternatively, in some variations, the report is sent to a physician who may manually or semi-manually interpret the results, including risk factors and symptoms, and contact the patient directly, including via an app.

[0069] FIG. 7 illustrates an example of a patient 700 holding a signal collection device 703 on their chest. The signal collection device includes a pair of extendable / pivoting chest electrodes 709, 711 that, when extended, contact the chest (positioned vertically as shown) at least 10 cm apart. Two finger electrodes, one 707 on the left and one 705 on the right, complete electrical contact and are used to hold the small, lightweight device to the chest as shown. These contacts allow for the determination of three highly orthogonal leads (between the finger electrodes, between the chest electrodes, and between the center point of the resistive network between the finger electrodes and one of the chest electrodes). The device may wirelessly communicate with a mobile communication device (e.g., a smartphone) that may include an app (software or firmware) to verify signal quality and / or perform additional recordings. The app may provide visual, auditory, tactile, or some combination of these indications that a recording has occurred. Recordings may be transmitted to a remote server, as shown schematically in FIG. 8.

[0070] 8 schematically illustrates an example system including a signal acquisition device 800 that can be used to determine three orthogonal leads 804 that precisely define a cardiac vector, which can then be transmitted to a patient's mobile telecommunications device 806 (e.g., phone, i-pad, wearable electronic device, etc.) that can process and / or verify signal quality and store and / or transmit the signals to a remote server 810. The remote server can communicate with the patient (e.g., and with the patient's mobile telecommunications device), or with a monitoring service and / or physician (not shown).

[0071] The methods and devices described herein may be used in conjunction with (and may be improvements to) U.S. patent application Ser. No. 15 / 096,159, filed April 11, 2016, entitled "MOBILE THREE LEAD CARDIAC MONITORING DEVICE AND METHOD FOR AUTOMATED DIAGNOSTICS," which claims priority to U.S. provisional patent application Ser. No. 62 / 145,431, filed April 9, 2015, entitled "MOBILE THREE LEAD CARDIAC MONITORING DEVICE AND METHOD FOR AUTOMATED DIAGNOSTICS," which applications are incorporated herein by reference in their entireties.

[0072] For example, the three-lead mobile cardiac monitoring devices having the first, undeployed, and second deployed configurations described herein may be used for automatic, remote diagnosis of cardiac conditions, including automated diagnostic methods using these improved handheld cardiac devices. These methods and devices may implement a risk scoring model based on three risk factors: pre-existing risk associated with the patient's risk factors, chest pain risk associated with current symptom risk, and recorded cardiac signals. Because these methods and devices use risk factors and current symptoms as additional inputs in addition to three orthogonal cardiac signal leads, they may detect not only AMI but also other cardiac conditions, such as angina pectoris. Additionally, they may provide accurate cardiac diagnosis using manually entered patient-related data, particularly in cases where cardiac signal recordings have low accuracy and precision, e.g., due to measurement interference. Thus, by enabling not only automatic but also highly accurate diagnosis of serious cardiac conditions, the methods and devices described herein may improve the operation of current solutions. The methods and devices may be configured to include data acquisition, data processing (e.g., application of a scoring model), and transmission of diagnostic information about the cardiac condition to the patient. This method may be implemented in an apparatus configured as a handheld device that allows the patient to input patient-related data (e.g., pre-existing risk and current symptom risk data), record cardiac signals, and retrieve previously stored cardiac risk-related data in situations where symptoms are associated with an ongoing AMI or similar situations. Any of these systems may include a three-lead mobile cardiac monitoring device having a first, compact, undeployed configuration and a second, deployed configuration as described herein. These systems may also include a user interface for inputting the patient's cardiac risk factor data and current symptom data in text format, as well as memory for storing the patient's cardiac risk factor data. Once acquired, the data may be transmitted to a remote processor. The processor may be configured to provide diagnostic information to the patient and transmit the diagnostic information back to the handheld device. The patient may decide to take further action, such as seeking emergency medical care, based on the received information. The handheld device may communicate the diagnostic information to the patient via a distinctive sound, audio message, or graphical display.The processor may be configured via hardware, software, firmware, etc. to process the received signals and generate a differential signal to reliably extract information relevant to detecting AMI.

[0073] For example, a three-lead mobile cardiac monitoring device having a first, compact, undeployed configuration and a second, deployed configuration described herein can be configured to be operated by a patient when a cardiac symptom occurs. The device can include storage (e.g., memory) for storing data about the patient's cardiac risk factors and other data, and cardiac signal recording components (e.g., electrodes, circuitry, and a controller) for recording the patient's cardiac signals. The recording components can be similar to those disclosed in International Publication No. WO 2016 / 164888 by Bojovic et al., as discussed above. Equipping the device with a graphical user interface (e.g., a touchscreen or a screen and keyboard) allows patient-related data (risk factors and current symptoms) to be entered, and diagnostic messages can be communicated to the patient. Diagnostic information can also, or alternatively, be communicated to the patient through a speaker or distinctive sound or voice message. Communication can occur via a wired or wireless connection to a separate user-operated device, such as a smartphone or tablet.

[0074] As described above, a three-lead mobile cardiac monitoring device having a first, compact, non-deployed configuration and a second, deployed configuration can be configured to record three substantially orthogonal cardiac signal leads using two chest electrodes and two non-chest (finger) electrodes. In some electrode configurations, the device can have a ground electrode integrated somewhere on the surface of the device.

[0075] The three-lead mobile cardiac monitoring device having a first, compact, undeployed configuration and a second, deployed configuration described herein can have various electrode configurations for recording three orthogonal cardiac lead signals. In one embodiment, the handheld device has two chest recording electrodes, one finger recording electrode on the left side of the device, one (or in some variations, two) finger electrodes on the front of the device, and one recording and one ground electrode. The optimal position for the handheld device on the chest is with the device centered on the left side of the chest approximately above the center of the myocardium. In this position, the chest electrodes are approximately on the midclavicular line, a vertical line passing through the midpoint of the clavicle, similar to the V4 electrode on a conventional ECG, and the lower chest electrode is approximately at the level of the lower edge of the sternum.

[0076] A four-electrode recording configuration (e.g., with two chest electrodes and two finger electrodes) can meet the requirement of high orthogonality by recording signals in three major body directions: horizontal (left arm-right arm), sagittal (front-to-back), and craniocaudal (head-to-toe). For example, horizontal signals can be obtained by measuring leads between the left and right arms. Craniocaudal signals can be obtained by measuring leads between two chest electrodes, with the distance between the chest electrodes in the craniocaudal direction being at least 5 cm, preferably greater than approximately 10 cm, so as to be greater than the approximate diameter of the myocardium. In the ideal case, sagittal signals are measured between the patient's back and chest, which is not possible under the constraints of using only one finger electrode and one chest electrode. To overcome this, a central point (CP) close to the cardiac electrical center is established in a simple resistive network. To record approximately sagittal leads, the voltage of the lower chest electrode is recorded with respect to the central point (CP), which is acquired using two hand electrodes and two resistors. The two resistors may be equal, each approximately 5 kOHM, or may be unequal, with the first resistor between the left-hand electrode and the CP being approximately 5 kOHM and the second resistor between the right-hand electrode and the CP being approximately 10 kOHM. This asymmetry reflects the left-side position of the heart in the torso, thus shifting the CP to approximately the electrical center of the heart. In this manner, a nearly orthogonal three-lead system is obtained.

[0077] Other similar lead configurations containing the same CP can be selected using the same set of two chest electrodes and two hand electrodes. For example, such lead configurations can be nearly orthogonal when both chest electrodes are used to record leads with the CP reference electrode. Another possibility for defining the CP is to use three electrodes, two hand electrodes and one chest electrode, and three resistors connected in a Y (star) configuration.

[0078] Other lead configurations that do not include a CP can also be used, such as a configuration that records two chest electrodes and a right-hand electrode signal relative to a left-hand electrode signal. Such configurations without resistors or CPs have higher noise immunity, e.g., to 50-60 Hz electrical noise, but have lower orthogonality in orthogonal lead directions than the described configurations that use CPs. Generally, any other lead configuration using the same four electrodes described (20 configurations in total without CPs) will result in leads that capture diagnostic signals in all three directions due to their non-coplanar nature, but may lack a high degree of orthogonality. However, these configurations may have different levels of orthogonality depending on the use of right-hand electrodes. A configuration that uses a right-hand electrode as a common reference electrode for all three leads may have the lowest orthogonality because the right-hand electrode is the farthest from the heart of the four electrodes and therefore has the smallest angle between the vectors corresponding to the three leads. However, this configuration with the lowest orthogonality is optimal for reconstructing a 12-lead ECG based on three-lead signals because it has less non-dipole content. Nevertheless, the signals obtained using this configuration can be used with or without the inclusion of 12-lead reconstruction.

[0079] The validity of the described solution is not affected if one or more chest electrodes are added to the back of the device, and one or more corresponding additional leads are recorded and used in the diagnostic algorithm, nor is the validity affected if the front electrode is pressed against the palm or other parts of the hand rather than the fingers.

[0080] For example, the devices described herein can be used for remote diagnosis of cardiac conditions such as acute myocardial infarction (AMI), atrial fibrillation (AFib), and others. In particular, described herein is a handheld device with a specialized electrode configuration that enables recording three orthogonal cardiac lead signals in an orientation-specific manner and transmitting these signals to a processor (e.g., a PC or other computing device). The processor can be configured to diagnose / detect AMI and also transmit diagnostic information to the handheld device. The handheld device can communicate the diagnostic information to the patient via a distinctive sound, a voice message, or via a graphical display. The processor can be configured via hardware, software, firmware, etc. to process the received signals, generate a difference signal, and extract information reliably related to the detection of AMI (and additional information of clinical relevance). Thus, these devices and methods perform automatic detection of cardiac conditions based on a three-lead system without the need for 12L ECG reconstruction, reducing or eliminating the need for medical personnel to interpret ECGs, unlike prior art systems that typically rely on medical personnel for such determinations. The automated diagnostic methods described herein, in combination with improved handheld cardiac devices, address many of the needs and problems present in other systems.

[0081] For clarity, described herein is a three-lead cardiac recording device for user placement on the chest that includes electrode placement on both the anterior and posterior sides (or, alternatively, on one or more sides, e.g., the anterior oblique side) so that the device can be held in both hands of the user in a predetermined orientation to record three-lead cardiac signals when held to the user's chest. To perform the above-described functions, the handheld device may record the three leads without the use of cables (e.g., it may include only surface electrodes that are held or retained on the body). Furthermore, the resulting three leads are non-coplanar and as close to orthogonal as possible. Finally, at least one electrode may be attached to the front (and / or oblique side) of the device opposite the chest side to generate the force necessary to hold the device to the chest. The apparatus and methods described herein do not require reconstruction of a 12L ECG from the three measured leads, and therefore do not impose a requirement for low non-dipole content.

[0082] The three-lead mobile cardiac monitoring device described herein, with the device in a first, undeployed configuration and a second, deployed configuration, is mechanically stable, allowing for good electrical contact with the chest, and is configured to avoid the possibility of finger contact switching. The handheld device can be placed on the chest with its center on the left side of the chest, approximately above the center of the myocardium. In this position, the chest electrode is approximately on the midclavicular line, a vertical line passing through the midpoint of the clavicle, similar to the V4 electrode of a conventional ECG, and the lower chest electrode is approximately at the level of the lower edge of the sternum. Horizontal signals can be obtained by measuring leads between the left and right hands. Cranial-caudal signals can be obtained by measuring leads between two chest electrodes, with the distance between the chest electrodes in the craniocaudal direction being at least 5 cm, preferably greater than about 10 cm, so as to be greater than the approximate diameter of the myocardium. In an ideal case, sagittal signals are measured between the patient's back and chest, which is not possible within the constraints of using only finger and chest electrodes. To overcome this, a simple resistor network is used to establish a midpoint (CP) near the heart's electrical center. To record leads in a roughly sagittal orientation, the voltage at the lower chest electrode is recorded relative to the midpoint (CP), which is obtained using two hand electrodes and two resistors. The two resistors can be equal, approximately 5 kΩ each, or unequal, with the first resistor between the left-hand electrode and the CP being approximately 5 kΩ and the second resistor between the right-hand electrode and the CP being approximately 10 kΩ. This asymmetry reflects the left-side position of the heart in the torso, thus shifting the CP to approximately the heart's electrical center. This results in a roughly orthogonal three-lead system.

[0083] The three-lead mobile cardiac monitoring device having the first, compact, non-deployed configuration and the second, deployed configuration described herein may be configured as a stand-alone device incorporating an ECG recording module including an amplifier and A / D converter, a data storage module, a communications module operating on GSM, WWAN, or similar telecommunications standards for communication with a remote processor (e.g., PC computer, pad, smartphone, etc.), and circuitry (e.g., Wi-Fi, Bluetooth, etc.) for communicating diagnostic information to a user. Alternatively, it may be implemented in conjunction with a mobile phone.

[0084] The signal processing and diagnostic software can also run on a processor (e.g., a microprocessor) including a processor integrated into the handheld device, rather than running on a remote processor (e.g., a PC computer). In this case, communication of recorded information to the remote computer is no longer necessary, except for back-up of data and processing. Also, when diagnostic processing is performed by a remote processor, a back-up version of the software running on the microprocessor can be integrated into the handheld device for use in situations where the user is in a zone outside of wireless network coverage.

[0085] Also described herein are methods and apparatus for automated detection of AMI (or the underlying physiological process, ischemia) using a three-lead mobile cardiac monitoring device having a first, compact, undeployed configuration and a second, deployed configuration as described herein. These automated systems include three cardiac leads that are nearly orthogonal and store most of the diagnostic information present in a traditional 12-lead ECG. Each user can be enrolled in the diagnostic system by performing an initial transmission of their own asymptomatic cardiac recording with the three cardiac leads. This initial recording can be used as a reference recording for AMI detection in diagnostic recordings (which refers to further recordings of the same user's three cardiac leads). The availability of a reference cardiac recording can distinguish between old and new ST-segment elevation (STE) or equivalent parameters, and other cardiac signal changes may also be suggestive of AMI, providing a tool for automated AMI detection that may have diagnostic accuracy comparable to that of human ECG interpretation.

[0086] In one example, a user may place the device in a different position compared to the reference position, which can compromise diagnostic accuracy. This misplacement equates to a virtual shift of the cardiac electrical axis in the 3D vector space defined by the three cardiac leads. In some variations, this angular shift can be calculated for each test recording and compared to the reference recording. If the angular shift is greater than a threshold, such as 15 degrees, the user can be warned to select a position closer to the reference position. If the shift is less than the threshold, it can be corrected by rotating the signal loop of the test recording in 3D vector space to obtain a signal approximately equivalent to the reference signal.

[0087] In some variations, a method for automatic detection of AMI (or ischemia) includes the following steps: placing the device at a recording location on a user's chest; acquiring an initial three-lead cardiac recording using a three-lead mobile cardiac monitoring device having a first, non-deployed configuration and a second, deployed configuration as described herein and communicating the signals to a processing unit; storing the first recording as a reference recording in a database of the processing unit for further comparison with any subsequent diagnostic recordings; acquiring a three-lead cardiac diagnostic recording and communicating the signals to the processing unit; and processing the resulting signals. Processing by the processing unit of the stored reference signals and the signals of the diagnostic recording may include the following steps: pre-processing to remove power line interference, baseline fluctuations, and muscle noise; obtaining a typical heart rate using a fiducial point and average heart rate procedure; checking for left and right finger switching; and performing heart rate alignment to place the typical heart rates of the reference and test recordings in the same time frame so that corresponding points are synchronized. Correcting chest electrode misplacement in the recording of the test signal by correcting for cardiac electrical axis deviation in the vector space of the three cardiac leads. calculating a difference signal representative of changes between the baseline and diagnostic three cardiac lead signals; detecting cardiac signal changes indicative of ischemia by comparing parameters of the test recording with the baseline recording or by comparing parameters of the difference signal with predetermined thresholds; communicating the information to the device by the processing unit; and finally, communicating the diagnostic information to the patient by the device.

[0088] STE, typically measured at the J point or up to 80 milliseconds later, is the most common ECG change in cases of ischemia. Using STE as a parameter, ischemic changes can be detected by comparing the STE of a test recording with a reference recording. Ischemic changes can also be detected by measuring the vector difference (STVD) of the ST vector in the vector space defined by three specialized cardiac leads, using the reference recording as a reference. As noted above, these parameters (e.g., ST, J, STVD, STE) are defined for traditional 12-lead ECG signals, but refer to equivalent measures determined for the three cardiac leads (orthogonal signals) described herein. Thus, these equivalent points, regions, or phenomena (e.g., STE, ST, J, STVD, etc.) can be identified by comparing the cardiac signals described herein with traditional ECG signals, including traditional 12-lead ECG signals.

[0089] Other parameters of the cardiac signal may also be used for comparison with a baseline reference signal, such as the "clew," defined as the radius of a sphere enclosing the vector signal hodograph between points J and J+80 ms.

[0090] Cardiac signals for an individual are highly repeatable in terms of their shape. Changes in signal shape are generally small for healthy, or stable, individuals. For example, changes in the position of the heart relative to the rib cage can shift the cardiac electrical axis by up to 10°. However, conditions in which signal shape changes over time are observed, such as STE caused by bilateral early repolarization (BER). Such signal changes can be highly individual and significant. To correct for such changes, several baseline recordings acquired by the user over time can be used to create reference values that form a 3D contour in a vector space defined by three specific cardiac leads (rather than a single point when a single baseline recording is used). When using such a 3D contour reference value, the ST vector difference (STVD) can be defined as the distance from the 3D contour rather than from a reference ST vector. When more than one parameter is used for ischemia detection, such a reference contour can be constructed as a hypersurface in a multidimensional parameter space defined by such parameters. In this case, the hyperdistance from the reference hypersurface is defined within this parameter space.

[0091] In some conditions, signal shape changes may be intermittent (the condition "comes and goes"), such as Brugada syndrome, Wolff-Parkinson-White syndrome, and branch-branch block (BBB). To correct for signal changes in such conditions, two groups of reference recordings (e.g., at least two recordings) can be used to define a reference value: one with a normal signal and one in which an intermittent condition exists. These two groups form two 3D contours in vector space to form a reference value for comparison. These two 3D contours may or may not overlap. If no overlap is observed, the ST vector difference (STVD) will be defined as the distance from the closest point on the two 3D contours. When more than two parameters are used for AMI / ischemia detection, such reference contours can be constructed as two hypersurfaces in a multidimensional parameter space defined by these parameters. In this case, the hyperdistance from the reference hypersurface is defined within this parameter space.

[0092] The primary use of the methods described herein can be applied to the most urgent cardiac diagnosis - detection of AMI. Additionally, diagnostic methods (e.g., software) on a remote processor (or integrated processor in a handheld device) can detect other cardiac conditions, such as chronic coronary artery disease (CAD), left ventricular hypertrophy (LVH), heart rhythm disorders such as cord branch block (BBB), Brugada syndrome, atrial fibrillation (AF), etc.

[0093] The methods described herein do not require reconstruction of a conventional 12-lead ECG recording, although they may be used for reconstruction. Many of the conditions detected above may require urgent treatment, albeit to a lesser extent than an AMI. Also, many of these conditions are transient and may be detected using the techniques described herein, but may not be present when the user later visits the clinic. In such cases, it is useful to present the ECG signal for the condition discovered at the time of recording, so that the physician can use it to confirm the diagnosis. Physicians are familiar with conventional 12-lead ECG recordings. Therefore, the three specialized cardiac leads recorded when the condition is discovered can be transformed to generate an approximate reconstruction of the conventional 12-lead ECG recording. Such a reconstruction is obtained by multiplying the three specialized cardiac leads by a 12-by-3 matrix. This matrix is a population matrix, i.e., a matrix with coefficients calculated as the mean or median of individual matrices obtained by simultaneously recording a conventional 12-lead ECG and the three specialized cardiac leads in a population of individuals, each of which is obtained using the least-squares method. The coefficients of such a matrix depend on the user's body shape. Therefore, rather than using a single population matrix, multiple matrices may be used that may be easy for users to obtain for a user population, each defined by simple parameters of body shape and structure such as gender, height, weight, chest circumference, etc. Also, the matrix coefficients may be determined as continuous functions of such body parameters.

[0094] FIG. 9A illustrates one variation of a method for operating a system for cardiac signal detection and / or diagnosis. In FIG. 9A, a user 2 records cardiac signals (e.g., two or more times), and a device 3 (specifically, a three-lead mobile cardiac monitoring device having a first, compact, undeployed configuration and a second, deployed configuration as described herein) processes the three orthogonal leads and compares time differences (e.g., baseline and test times). The device 3's processor can then determine whether the resulting differential signal indicates a cardiac problem and alert the user, who can then seek medical assistance as needed. FIG. 9B illustrates another variation of a system and method for detecting cardiac dysfunction, including a system 1 for remote diagnosis of AMI, including a handheld device 2 incorporating built-in electrodes for cardiac signal acquisition attached directly to the handheld device's housing 3 and a PC computer 4 connected to the device via a telecommunications link.

[0095] The three-lead mobile cardiac monitoring device having the first, compact, non-deployed configuration and the second, deployed configuration described herein may further incorporate cardiac signal recording circuitry including an amplifier and an analog-to-digital converter for amplifying signals detected by the electrodes, data storage (e.g., memory) for storing the recorded signals, and communication circuitry operating on GSM, WWAN, or similar telecommunications standards for communication between a remote processor 4 and visual and / or audio (e.g., monitor, speaker, etc.) for communicating diagnostic information to a user.

[0096] The three-lead mobile cardiac monitoring device having the first, compact, undeployed configuration and the second, deployed configuration described herein may communicate with a remote processor 4 via integrated communications circuitry. The remote processor 4 may communicate with a handheld device 2 via an integrated communications module. The processor 4 may be equipped with diagnostic software for processing received cardiac signals to generate diagnostic information and for transmitting the information back to the handheld device for conveying the diagnostic information to the patient via a microphone that generates characteristic sounds or audio messages, or in the form of graphic information via a display integrated into the device. As a result, the system is capable of performing automatic detection of cardiac conditions based on the three-lead system, without requiring expert interpretation of the processed diagnostic information. Alternatively, instead of a remote processor, the system may include a microprocessor integrated into the handheld device housing 3 for processing recorded cardiac signals to generate diagnostic information.

[0097] The example of Figure 10 shows a simple electrical method for obtaining the center point CP by connecting the electrodes on both hands through a simple resistive network with two resistors.

[0098] FIG. 11A shows a spatial diagram of a lead configuration according to one embodiment, illustrating the placement of active electrodes A, B, C, and D relative to the body, as well as the relative placement between the electrodes. FIG. 11B shows a simplified electrical scheme illustrating the same relative placement between the electrodes shown in FIG. 11A. To record a generally sagittal lead, hand electrodes C and D and two resistors R1 and R2 can be used to obtain the voltage at the lower chest electrode B about a center point CP. The two resistors R1 and R2 can be equal, approximately 5 kΩ each, or unequal, approximately 5 kΩ between the left-hand electrode and CP and 10 kΩ between the right-hand electrode and CP. This asymmetry reflects the left-side location of the heart in the torso, thus placing the CP point approximately at the electrical center of the heart. In this manner, a generally orthogonal three-lead configuration is obtained.

[0099] Figure 11C shows a spatial diagram of an alternative lead configuration including a central point CP using the same set of chest and hand electrodes A, B, C, and D, illustrating the relative placement of the electrodes along with their placement on the body. Figure 11D shows a simplified electrical scheme illustrating the same relative placement between electrodes A, B, C, and D shown in Figure 11C. This alternative lead configuration, using the central point CP to measure two leads between the CP and each of the chest electrodes, is also nearly orthogonal because chest electrodes A and B are used to record leads using the CP obtained using two hand electrodes C and D and two resistors R1 and R2 as the reference electrode.

[0100] Other lead configurations without a central point CP and resistors can also be used, such as the configuration shown in Figure 11E, which records signals from two chest electrodes and a right-hand electrode with a left-hand electrode. Two other similar configurations are shown in Figures 11F and 11G. Such configurations without resistors receive less external interference, such as 50-60 Hz electrical noise, but have less orthogonal lead orientations than those described above that use CPs. Generally, other lead configurations using the same four electrodes as those described result in non-coplanarity and therefore lack high orthogonality, although they capture diagnostic signals in all three directions. A total of 20 configurations are possible, including those shown in Figures 11E, 11F, and 11G, without CPs. However, these configurations have different levels of orthogonality depending on the use of right-hand electrodes. The configuration using the right-hand electrode as a common reference electrode for all three leads has the lowest orthogonality because the right-hand electrode is the farthest from the heart of the four electrodes and therefore has the smallest angle between the vectors corresponding to the three leads. Configurations using right-hand electrodes on two leads, such as the configuration shown in FIG. 11F, have good orthogonality, but best orthogonality is achieved with configurations using right-hand electrodes on only one lead, such as the configurations shown in FIGS. 11E and 11G.

[0101] 12 shows a block diagram of a method for automatic detection of AMI by a preferred embodiment of a three-lead mobile cardiac monitoring device having a first compact, undeployed configuration and a second deployed configuration as described herein. The method for automatic detection of AMI (or ischemia) may include all or some of the steps described below. First, place the device in a recording position on the user's chest.

[0102] The optimal position for the handheld device on the chest is with the center of the device approximately above the center of the myocardium and on the left side of the chest. In this position, the chest electrodes are approximately on the midclavicular line, a vertical line passing through the midpoint of the clavicle, similar to the V4 electrode on a conventional ECG, and the lower chest electrode is approximately at the level of the lower edge of the sternum. The user presses down on one active electrode and one ground electrode with the fingers of their left hand and one active electrode with the fingers of their right hand on the front of the device.

[0103] The method may also include obtaining an initial three-lead cardiac recording and communicating the signal to a processing unit. A user of the automated AMI diagnosis system may perform a three-lead cardiac signal recording by holding a handheld device against their chest for a short period of time (e.g., at least 30 seconds, at least 20 seconds, at least 10 seconds, at least 5 seconds, etc.). The recording is stored in the device's memory and then transmitted to a remote PC computer over a commercial communications network.

[0104] The method also includes storing the initial recording in the processing unit's database as a reference. After performing a first transmission of their cardiac signals, the cardiac signal record is stored in the remote processor and the user can be registered with the diagnostic system. Prior to this first transmission, the user or their MD / nurse (via a dedicated website) enters medical data such as age, sex, risk factors for cardiovascular disease, etc., and indicates whether they currently have chest pain or other symptoms suggestive of ischemia. If the answer is negative, this initial cardiac recording is retained in the diagnostic system as a baseline record to serve as a reference value for comparison in further transmissions when symptoms suggestive of ischemia occur.

[0105] The method may further include obtaining a three-lead cardiac diagnostic recording and communicating the signals to a processing unit. Subsequent recordings after the baseline recordings are accepted and stored in a database are considered diagnostic recordings. A user of the automated AMI diagnosis system performs a diagnostic recording of the three-lead cardiac signals by holding the handheld device against their chest for at least 10 seconds. The diagnostic recording is stored in the device's memory and then transmitted to a remote PC computer over a commercial communications network.

[0106] Generally, the methods described herein may include processing stored baseline and diagnostic record signals by a processing unit. Processing may include preprocessing. For example, the device / method may be configured to record Va, Vb, and Vc into three specialized leads that are recorded using a handheld device. Before any analysis can be performed, contaminants such as power line interference, baseline fluctuations, and muscle noise must be "cleaned" from the cardiac signal. The former two are removed using standard adaptive filtering and cubic spline techniques, respectively, while the latter is suppressed using a time-averaged median heart rate procedure.

[0107] To find the median heart rate, the entire cardiac signal is enumerated, resulting in a set of fiducial points S={P1, P2,..., P n} is obtained, and P i ={Q i ,R i ,J i ,T i , end} (or points equivalent to these points) is the reference point for the ith heart rate. Then, based on S, the signal is divided into n individual heart rates of equal length. Finally, the individual heart rates are synchronized using cross-correlation (CC), and for each sample, the median of all n heart rates is calculated. Thus, the single most representative median heart rate represents the entire cardiac signal. The set of reference points associated with the median heart rates, P = {Q, R, J, T, T end} is simply calculated as the median of the individual heart rate reference points.

[0108] Techniques for obtaining a typical heart rate rather than a median heart rate may also be used. Various techniques such as wavelet transforms, support vector machines, etc. may be used to enumerate the cardiac signal as a reference point for each heart beat.

[0109] The same preprocessing procedures are used for both baseline and diagnostic recordings.

[0110] If a lead recorded between the left and right hands, or any other lead that captures a signal horizontally, is reversed, the user is alerted to repeat the recording using the correct recording position.

[0111] The processing may also include heartbeat alignment. For example, the device or method may be configured to let B and D refer to median heart rates extracted from the reference and diagnostic cardiac signals, respectively, with PB and PD being their associated reference points. The goal of heartbeat alignment is to bring B and D into the same time frame so that corresponding points are precisely synchronized. This requires finding a transformed B, called B*, that is optimally synchronized with D. The applied transformation is a piecewise uniform resampling of B, so that corresponding segments of B* and D, defined by PB and PD, respectively, have the same number of samples. The optimal alignment is obtained by searching for the reference point PB* that optimizes a cost function or similarity measure (SM) that quantifies the alignment.

number

[0112] In this embodiment, we used CC, a commonly used SM for shape-based alignment problems. However, because the shapes of B and D are significantly different, using CC alone may lead to alignment errors. Therefore, the reference point P B is assumed to be known accurately, so P B A weighting function f that penalizes large deviations from wi Introduce.

number

number

[0113] Finally, B* is found by finding the optimal value of SM given by equation (3) according to equation (1).

[0114] Processing may also include correction for chest electrode misplacement. During normal use of the handheld device, the chest electrodes are not placed in the same location each time, which can lead to changes in the shape of the cardiac signal even in the absence of any pathology. Assuming constant lead position, this change is modeled as a "virtual" cardiac electrical axis deviation in the Va, Vb, and Vc lead vector space, where the cardiac electrical axis is represented by the R vector—the cardiac vector at the largest moment of the QRS complex (or the equivalent region of the three-lead cardiac signal described herein). However, this is an undesirable characteristic because it results in a large difference signal ΔD even in the absence of pathology-induced changes. To overcome this problem, D is transformed so that D* = TD, so that its cardiac electrical axis overlaps with that of B*. A transformation T is calculated using a least-squares method and the Q-J segments (QRS complexes) of D and B* as inputs.

[0115] Generally, processing may also include calculating a difference signal representing the change between the reference and diagnostic cardiac lead signals. The difference signal ΔD* is calculated as follows:

number

[0116] Finally, such a difference signal ΔD* reflects only pathology-induced changes and is independent of cardiac axis deviation.

[0117] Since the quality of device installation error correction decreases with increasing signal axis angle deviation, the user is prompted to select a position closer to the reference position when the angle change is greater than a threshold value such as 15 degrees.

[0118] The processing methods and devices described herein may also include detection of changes due to ischemia. STE is the most common ECG change in cases of ischemia, usually measured at the J point or up to 80 ms later. In this solution, ischemic changes are detected by comparing the test recording with a reference recording. In a preferred embodiment, the parameter or "marker" for ischemia detection is the vector magnitude of the corrected difference signal ΔD* 80 ms after the J point (J+80 ms) compared to the STVM (or equivalent region of the cardiac signal as described herein), i.e., a predetermined threshold such as 0.1 mV.

[0119] In other embodiments, vector magnitudes at other time points can be used as markers of ischemia, such as the J point, J+60 ms, Tmax, etc. Other markers representing the shape of the ST segment (the segment of the ECG signal between the J and J+80 ms points, or similar) can be used. One such marker is the "clew," which is defined as the radius of a sphere enclosing the vector signal hodograph between the J and J+80 ms points. Other composite markers may also be used, such as logistic regression using a linear combination of STVM and clew markers.

[0120] To correct for signal shape changes over time, several reference recordings acquired by the user over a period of time can be used to create a reference value that forms a 3D contour in the vector space defined by three specific cardiac leads (instead of a single point when a single reference recording is used). When using such a 3D contour reference value, the ST vector difference (STVD) is defined as the distance from the 3D contour rather than from the reference ST vector. When more than one parameter is used for ischemia detection, such a reference contour will be constructed as a hypersurface in a multidimensional parameter space defined by such parameters. In this case, the hyperdistance from the reference hypersurface is defined in this parameter space.

[0121] For users with cardiac conditions involving intermittent cardiac shape changes, correction for such changes may be achieved by defining a reference value by forming two groups of reference recordings (at least two recordings), one with normal signals and one with this condition. These two groups may then be formed into two 3D contours in vector space to form a reference value for comparison, and the ST vector difference (STVD) may be defined as the distance from the closest points on the two 3D contours. When more than two parameters are used for ischemia detection, these reference contours may be constructed as two hypersurfaces in a multidimensional parameter space defined by such parameters. In this case, the hyperdistance from the reference hypersurface may be defined in this parameter space.

[0122] Any of these methods and devices may be configured to communicate information to the device by the processing unit. Generated diagnostic information may be transmitted to the device memory from a remote processor (e.g., a PC computer, server, etc.) over a commercial communications network. The methods and devices may also be configured to convey diagnostic information to the patient by the device. Received diagnostic information may be presented to the user in the form of distinctive sounds, voice, graphics, or text.

[0123] Additionally, an approximate conventional 12-lead ECG signal can be sent to the user's physician for evaluation. By transforming the three specialized cardiac lead signals recorded by the user, this signal can be generated as an approximate conventional 12-lead reconstruction. This reconstruction is obtained by multiplying the three specialized cardiac leads by a 12-by-3 matrix. In one embodiment, this matrix can be obtained by a computer using a general approach to electrical potential distribution on the surface of the human body, similar to that described above for defining a conventional vectorcardiogram. In another embodiment, this matrix is obtained as a population matrix, a matrix with coefficients calculated as the mean or median of individual matrices obtained by simultaneously recording a conventional 12-lead ECG and three specialized cardiac leads in a population of individuals, with each individual matrix being determined using the least-squares method. In yet another embodiment, multiple matrices can be used for corresponding user groups defined by simple parameters of body shape and structure, such as gender, height, weight, chest circumference, etc., which can be easily obtained by the user. The matrix coefficients can also be determined as continuous functions of such body parameters.

[0124] Equipment arrangement The optimal placement of a three-lead mobile cardiac monitoring device having the first, compact, undeployed configuration and the second, deployed configuration described herein is on the chest, with the center of the device on the left side of the chest, approximately above the center of the myocardium. In this position, the right edge of the device is approximately 3 cm from the midsternal line, the vertical midline of the sternum, and the lower edge of the device is approximately at the level of the lower edge of the sternum. In an ideal case, the user selects the optimal position on the chest for an initial baseline recording and repeats this position for each future diagnostic recording. In this situation, cardiac recordings are repeatable, and cardiac signal changes suggestive of an AMI are readily detectable.

[0125] Risk Assessment Methodology A risk assessment model for determining the probability that a patient has a serious condition such as acute myocardial infarction (AMI) or cardiac ischemia is based on three types of input data: a) patient risk factors, b) cardiac signal recordings, and c) current symptom data.

[0126] The evaluation method may include the following steps: 1) patient self-entering risk factor data and storing the data in system memory; 2) patient self-recording a 3-lead ECG using a handheld device; 3) patient self-entering current symptom data; 4) transmitting cardiac signal and current symptom data to a remote processor / server; 5) processing the data in the processor / server; 6) transmitting a diagnostic message to the handheld device; and 7) communicating the diagnostic message to the patient using the handheld device's graphical or audio interface. Step 1 is performed during the patient's first use of the device / system. Steps 2-7 are performed when the patient has symptoms or desires a cardiac screening. The diagnostic message may refer to calling emergency services, waiting for another measurement, or ignoring the symptoms. In other words, the message has the form of instructions to the patient on what action to take.

[0127] In some embodiments, the automated diagnostic system is based on cardiac risk assessment using three risk components: cardiac signal risk (CSR), pre-existing risk (PER - patient risk factors stored in memory), and chest pain risk (CPR - current symptom risk). Each risk is described by three risk levels: H - high, I - medium, and L - low. The cardiac risk decision value is used to select the diagnostic message to be delivered to the patient.

[0128] The final diagnostic message to the patient is given after up to three repeated diagnostic sessions, 5-10 minutes apart. Each diagnostic session consists of a cardiac recording and a Chest Pain Questionnaire (CPQ).

[0129] Cardiac Signal Risk (CSR) Cardiac signal risk assessment can include three cardiac leads, which are nearly orthogonal and store most of the diagnostic information present in a traditional 12-lead ECG. Each user can be enrolled in the diagnostic system by performing an initial transmission of an asymptomatic cardiac recording with three cardiac leads. This initial recording can be used as a reference recording for AMI detection in diagnostic recordings (which represent further recordings of the three cardiac leads for the same user). The availability of a reference cardiac recording allows for differentiation between new and old STEs (ST-segment elevation) and other cardiac signal changes suggestive of AMI.

[0130] STE is the most common ECG change in cases of ischemia, usually measured at the J point or up to 80 ms later. In this solution, ischemic changes are detected by comparing the diagnostic recording with the baseline recording. In a preferred embodiment, the parameter or "marker" for ischemia detection is STVM, and the vector magnitude of the difference signal ΔD* at 80 ms after the J point (J+80 ms) represents the change between the baseline and diagnostic three cardiac lead vectors. The difference signal ΔD* is calculated (as described above) as equation (4):

number

[0131] D* is the diagnostic three-lead cardiac vector and B* is the reference three-lead cardiac vector.

[0132] In other embodiments, vector magnitudes at other time points may be used as markers for ischemia, such as the J point, J+60 ms, Tmax, etc. Other markers indicative of the shape of the ST segment (the segment of the ECG signal between the J and J+80 ms points or similar segments) may be used. Such a marker is the "clew," which is defined as the radius of a sphere enclosing the vector signal between the J and J+80 ms points. Other composite markers may also be used, such as logistic regression using a linear combination of STVM and clew markers.

[0133] In some embodiments, automatic detection of cardiac signal signs of ischemia can be based solely on diagnostic recordings, without the use of reference recordings. This approach is used in cases where the patient does not own an automated device, and therefore reference recordings are not stored in the device's memory. In this case, B* (the reference cardiac 3-lead vector) can simply be set to zero.

[0134] In some embodiments, the automated detection of cardiac signal signs of ischemia may be based on a conventional approach, where the primary signs of ischemia are ST-segment shift and T-wave inversion. These parameters, or "markers," of ischemia are defined on a conventional 12-lead ECG. A conventional 12-lead ECG may be synthesized from three orthogonal leads by using a matrix transformation using an individual matrix or a population reference matrix.

[0135] The thresholds for classifying CSR (H-high, I-medium, L-low) are defined as follows: H-When the CSR marker value is above a threshold (TH2). This threshold may correspond to the criteria for STEMI based on a 12-lead ECG, such as 0.2 mV. I-When the CSR marker value is between TH1 and TH2. TH1 may be the optimal threshold for separating AMI and non-AMI signals, such as 0.1 mV. L-When the CSR marker value is below TH1.

[0136] Thresholds TH1 and TH2 may be determined from prior experience and medical literature, or may be optimized using cardiac signal recordings from a clinical dataset.

[0137] Existing Risk (PER): (H - High, I - Medium, L - Low) In some variations, the pre-existing risk (PER) determination algorithm is based on the 2013 ACC / AHA Index for the Assessment of Cardiovascular Risk. Variables with statistical merit for inclusion in the risk assessment equation were age, total cholesterol, high-density lipoprotein cholesterol, systolic BP (including treated or untreated status), diabetes mellitus (DM), and current smoking status. The estimated 10-year risk of cardiovascular disease (ASCVD) events is used as a cutoff between low (L for <5%), intermediate (I for 5-10%), and high (H for >10%) risk levels. A "pooled cohort equation" of exponential type is used for the pre-existing risk (PER) variable in the calculation.

number

[0138] The variable IndividualSum may be calculated as a linear combination of the individual risk factors. IndividualSum = C1*In(age) + C3*In(total cholesterol) + C4*In(age)*In(total cholesterol) + C5*In(HDL) + C6*In(age)*In(HDL) + C7*Post-treatment systolic BP*In(systolic BP) + In(HDL) + C9*(1-Post-treatment systolic BP)*In(systolic BP) + C11*smoker - C12*In(age)*smoker + C13*diabetes

[0139] The coefficients C1-C13 and corresponding risk factor values may be used with corresponding predetermined values (such as, but not limited to, Goff DC Jr, Lloyd-Jones DM, Bennett G, et al., "2013 ACC / AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology / American Heart Association Task Force on Practice Guidelines. Circulation 2014):129(2):S49-S73, which is incorporated herein by reference in its entirety). Alternative scores may also be used for pre-existing risk (PER) assessment.

[0140] Chest pain risk (CPR): (H - high, I - medium, L - low) At the time of cardiac symptom occurrence, the chest pain risk (CPR-Current Symptom Risk) parameter is manually entered by the patient via keyboard or touch screen. The chest pain risk parameter is chosen based on literature data and the inventor's own clinical experience.

[0141] In a preferred embodiment, a nine parameter questionnaire list may be used as shown in Figure 13. As also shown in Figure 13, each response to the questionnaire is assigned a specific number of points between -1 and 3. The value of the CPR variable is calculated as the sum of the points for all nine parameter questionnaires.

[0142] CPR risk levels are estimated by cutoffs between low (L for <2 points), intermediate (I for 2-5 points), and high (H for >5 points) risk levels.

[0143] In other embodiments, alternative questionnaires / answers, point numbers, or cutoff values may be used.

[0144] Post-test AMI risk (PTR): (H - high, I - medium, L - low) The post-test AMI risk (PTR) assessment can have three levels (H - high, I - medium, L - low) based on the use of three risk components: cardiac signal risk (CSR), pre-existing risk (PER), and chest pain risk (CPR). There are 27 possible combinations of CSR, PER, and CPR values. The PTR value for each of these combinations is established based on literature data and the inventor's own clinical experience. The values of all 27 possible combinations and the corresponding PTR values are listed in Figure 14.

[0145] Diagnostic report (message) A diagnostic report is given to the patient after completing the diagnostic evaluation, which may have one, two or three diagnostic sessions (cardiac signal recording and completion of a chest pain questionnaire) performed by the patient at predetermined time intervals, such as three sessions with a time interval of 5-10 minutes.

[0146] The diagnostic report provided to the patient consists of various diagnostic messages suggesting actions the patient should take. For example, the diagnostic message may suggest that the patient seek medical care immediately or receive reassurance regarding the benign nature of the symptoms. In a preferred embodiment, there are six possible messages: (1) The diagnostic system indicates that you are having a heart attack. Call emergency services immediately. (2) The diagnostic system indicates that you are likely having a heart attack. Call emergency services and go to the emergency room. (2A) You may be having angina. Try to relax in a quiet place, take nitroglycerin, and repeat the recording in 5 minutes. If the pain worsens and lasts longer than your usual angina, call emergency services. (3) Chest pain attacks may be a sign of a heart problem. Notify your doctor and discuss whether further testing is needed. If the pain returns, call emergency services. (3A) The diagnostic system indicates that you are having an angina attack. Upon diagnostic system evaluation, the pain resolves and the ECG returns to normal. If this attack feels like regular angina, no emergency action is necessary. If the pattern of your angina (severity, frequency, duration of pain) changes, you should notify your doctor immediately. (4) Based on the diagnostic system evaluation, your chest pain is most likely heart-related. You should mention this to your doctor at your next appointment. If the pain persists, it is up to you to decide whether to seek medical care.

[0147] Messages 2A and 3A are used only for patients experiencing angina, as reported when completing the Pre-existing Risk (PER) questionnaire.

[0148] The default diagnostic evaluation has three sessions. The diagnostic evaluation may be completed in fewer than three sessions if the diagnostic evaluation termination criteria are met.

[0149] In a preferred embodiment, a diagnostic message is selected based on PTR (post-test risk), CSR (cardiac signal risk), presence of chest pain, pre-existing angina, and the following set of rules:

[0150] Decision Rules 1. If the scores in the first, second, and third sessions are CSR = H, end the diagnostic evaluation and issue Message 1. 2. If the scores in the first, second, and third sessions are PTR = H and CSR < H, end the diagnostic evaluation and issue Message 2. 3. When the number of completed sessions is less than 3 and the score is PTR < H, send a request for an additional session. 4. After the third session, if PTR = I in any of the sessions and CP = 1 (persistence of chest pain) in the third session, Message 2 is issued. 5. After the third session, if PTR = I in any of the sessions and CP = 0 (cessation of chest pain) in the third session, Message 3 is issued (only for patients other than those with angina). 6. After the third session, if PTR = L in all three sessions and CP = 0 (cessation of chest pain) or CP = 1 (persistence of chest pain) in the third session, issue Message 4. 7. For a patient with angina, if the score in the first or second session is PTR = H and CSR < H, issue Message 2A. 8. For a patient with angina, if the score in the third session is CSR = I or CSR = H and CP = 0 (cessation of chest pain), issue Message 3. 9. For a patient with angina, if the score is PTR = I or PTR = H in either the first or second session and CSR = L and CP = 0 in the third session, issue Message 3A.

[0151] Figure 15 shows a flowchart of the algorithm based on rules 1-9 described above. The flowchart has two branches for patients with and without angina. Each branch has three recording sessions with possible exits defined by rules 1-2, and the assessment is based on the three recording sessions completed according to rules 3-9. Either exit algorithm issues messages 1-4 (circled in Figure 15) related to AMI assessment or messages 2A and 3A (rectangled in Figure 15) related to angina attack.

[0152] Any of the methods (including user interfaces) described herein may be embodied as software, hardware, or firmware, executable by a processor (e.g., a computer, tablet, smartphone, etc.), and described as a non-transitory computer-readable medium storing a set of instructions that, when executed by the processor, cause the processor to perform any of the steps including, but not limited to, displaying, communicating with a user, analyzing, adjusting parameters (including timing, frequency, intensity, etc.), making a judgment, alerting, and the like.

[0153] When a feature or element is referred to herein as being "on" another feature or element, it is either directly on the other feature or element, or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements present. When a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it will be understood that it may be directly connected, attached, or coupled to the other feature or element, or that intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intervening features or elements present. Although described or illustrated with respect to one embodiment, the features and elements so described or illustrated may apply to other embodiments as well. Those skilled in the art will also recognize that a reference to a structure or feature being disposed "adjacent" to another feature may have portions that are above or below the adjacent feature.

[0154] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. For example, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used herein, specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated with " / ."

[0155] Spatially relative terms such as "under," "below," "lower," "over," "upper," etc., may be used to facilitate the description of the relationship of one element or feature to another element or feature shown in the figures. It will be understood that the spatially relative terms are intended to encompass various orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were inverted, an element described as "under" or "beneath" the other element or feature would then be oriented "over" the other element or feature. Thus, the exemplary term "under" can encompass both an orientation above and below. The device may be otherwise oriented (rotated 90 degrees or at another orientation), and the spatially relative descriptors used herein will be interpreted accordingly. Similarly, terms such as "upwardly," "downwardly," "vertical," "horizontal," and the like are used herein for descriptive purposes only, unless otherwise specified.

[0156] The terms "first" and "second" may be used herein to describe various features / elements, but these features / elements should not be limited by these terms unless the context dictates otherwise. These terms may be used to distinguish one feature / element from another. Thus, a first feature / element described below may be referred to as a second feature / element, and similarly, a second feature / element described below may be referred to as a first feature / element, without departing from the teachings of the present invention.

[0157] Throughout this specification and the claims that follow, unless the context requires otherwise, the terms "comprise" and variations thereof, such as "comprises" and "comprising," refer to various components employed cooperatively in methods and articles (e.g., apparatus and methods, including compositions and devices). For example, the term "comprising" will be understood to mean the inclusion of any of the stated elements or steps, but not the exclusion of any other elements or steps.

[0158] Generally, any of the apparatus and methods described herein should be understood to be inclusive, or alternatively, all or a subset of the components and / or steps may be exclusive and may be expressed as "consisting of" or alternatively "consisting essentially of" various components, steps, subcomponents, or substeps.

[0159] As used in the specification and claims, including in the examples, and unless expressly stated otherwise, all numbers may be construed as if preceded by the words "about" or "approximately," even if these words are not explicitly stated. When the terms "about" or "approximately" are used to describe a size and / or location, they indicate that the stated value and / or location is within a reasonable expected range of values and / or locations. For example, a numerical value may have a value that is + / - 0.1% of the stated value (or range of values), + / - 1% of the stated value (or range of values), + / - 2% of the stated value (or range of values), + / - 5% of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical value recited herein should be understood to include about or approximately that value unless the context indicates otherwise. For example, if a value of "10" is disclosed, then "about 10" is also disclosed. Any numerical ranges set forth herein are intended to include all subranges encompassed therein. As will be appreciated by those skilled in the art, when a value is disclosed as "less than or equal to" that value, it is understood that "greater than or equal to that value" and possible ranges between those values are also disclosed. For example, if a value of "X" is disclosed, "less than or equal to X" as well as "greater than or equal to X" (e.g., X is a numerical value) are also disclosed. It is understood that data are provided throughout this application in several different formats, and that this data represents ranges for any combination of endpoints and starting points and data points. For example, if a specific data point "10" and a specific data point "15" are disclosed, it is understood that greater than 10 and 15, greater than or equal to 10 and 15, less than 10 and 15, less than or equal to 10 and 15, and equal to 10 and 15 are also considered to be disclosed as being between 10 and 15. It is understood that each unit between two specified units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0160] While various exemplary embodiments have been described above, any of several modifications may be made to the various embodiments without departing from the scope of the invention as set forth in the claims. For example, the order in which the various method steps described are performed is often changed in alternative embodiments, and one or more method steps may be omitted altogether in other alternative embodiments. Optional features of the various apparatus and system embodiments may be included in some embodiments and not included in other embodiments. Therefore, the above description is provided primarily for illustrative purposes and should not be construed as limiting the scope of the invention as set forth in the claims.

[0161] The examples and illustrations contained herein illustrate, by way of example, not limitation, specific embodiments in which the subject matter may be practiced. As noted above, other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Such embodiments of the inventive subject matter may be individually or collectively referred to herein by the term "invention" when more than one is actually disclosed, merely for convenience and without any intention to intentionally limit the scope of the present application to a single invention or inventive concept. Thus, while specific embodiments have been shown and described herein, any mechanism contrived to achieve the same purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover any and all modifications or variations of the various embodiments. Combinations of the above embodiments, as well as other embodiments not expressly described herein, will be apparent to those skilled in the art upon reviewing the above description. [Explanation of symbols]

[0162] 1 System 2 users 3 equipment 4 PC computers 10. Cabinet 12 sides 14 Hand electrode 16 Arm 18 Chest electrode 20 Back 22 plots 23 Short edge 24 Bottom 26 Side wall 28 Front wall 30 Opening 32 Distal opening 36 Tail part 34-pin 38 Sleeve 40 Coiled Torsion Spring 42 slots 44 First Tongue 46 Second Tongue 48 Side 55 Tip 56 sockets 60 Head part 61 Concave surface 63 Upper side of head 68 Upper side of the tail 72 bottom side 73 Depression 76 Chamfered part 78 Long edge 700 patients 703 Signal Collector 705,707 Finger electrode 709,711 Chest electrode 800 Signal Collector 804 Orthogonal Lead 806 Mobile Telecommunications Devices 810 Remote Server

Claims

1. 1. A three-lead mobile cardiac monitoring device comprising: a housing having a front surface and a rear surface; two chest electrodes; Two finger electrodes; two retractable arms pivotally attached to the housing at opposite ends; Equipped with the two finger electrodes are disposed on the front or edge of the housing, and the two chest electrodes are disposed on the retractable arm; Device.

2. 10. The device of claim 1, wherein each retractable arm has a recessed tapered portion at one end that accommodates one of the chest electrodes for acquiring signals from the patient's chest.

3. two generally columnar compartments on either side of the housing, each configured to receive the arm in a retracted position, each compartment having two side walls, a bottom, a front wall, and a pin, each pin connecting two opposing side walls of each compartment; The apparatus of claim 1 further comprising:

4. 4. The device of claim 3, wherein each arm includes a torsion spring coaxial with the pin, the spring having first and second tangs, the first tang mating with the arm and the second tang mating with the housing.

5. 2. The device of claim 1, further comprising a pair of compartments and one or more locks that hold each of the arms in a storage position within the compartment of the pair of compartments, each arm having two spring plungers arranged in a vertical cylinder on the side of the arm, so that the tip of each plunger is configured to fit into a recess formed in each side wall of the compartment.

6. 2. The device of claim 1, wherein the finger electrodes are disposed on chamfered portions of one or more long edges of the front surface, the chamfered portions being offset relative to a horizontal centerline of the front surface, and the arms are disposed adjacent to or on the short edges of the front surface on a vertical centerline.

7. 10. The device of claim 1, further comprising a pair of compartments each having an opening adapted to receive a portion of the one or two retractable arms.

8. 10. The device of claim 1, wherein the housing has a length-to-thickness ratio of about 15 or greater and a length-to-width ratio of about 1.6 or greater.

9. 10. The device of claim 1, wherein the distance between the chest electrodes in the unretracted position is greater than about 10 cm.

10. The device of claim 1 , wherein the angle between the arms in the unretracted position is approximately 135 degrees.

11. 1. A three-lead mobile cardiac monitoring device having a first compact, undeployed configuration and a second deployed configuration, a housing having a front surface and a rear surface; two chest electrodes; Two finger electrodes; two retractable arms pivotally attached to the housing at opposite ends; Equipped with the two finger electrodes are disposed on the front or leading edge of the housing and the two chest electrodes are disposed on the retractable arm; the retractable arm retracts flush with the back surface in the undeployed configuration and extends at an angle relative to the back surface in the deployed configuration; Device.

12. 12. The device of claim 11, wherein each retractable arm has a recessed tapered portion at one end that accommodates one of the chest electrodes for acquiring signals from the patient's chest.

13. 12. The apparatus of claim 11, further comprising two general compartments on each side of the housing, each configured to receive the arm in a retracted position.

14. 14. The device of claim 13, wherein each arm comprises a torsion spring having first and second tangs, the first tang mating with the arm and the second tang mating with the housing.

15. 12. The device of claim 11, further comprising a pair of compartments and one or more locks that hold each of the arms in a storage position within the compartments of the pair of compartments, each arm having two spring plungers arranged in a vertical cylinder on the side of the arm, so that the tip of each plunger is configured to fit into a recess formed in each side wall of the compartment.

16. The device of claim 11 , wherein the finger electrodes are disposed on chamfered portions of one or more long edges of the front surface.

17. 17. The device of claim 16, wherein the chamfered portion is offset relative to a transverse centerline of the front surface, and the arms are disposed adjacent to or at short edges of the front surface on a longitudinal centerline.

18. 12. The device of claim 11, further comprising a pair of compartments each having an opening adapted to receive a portion of the one or two retractable arms.

19. 12. The device of claim 11, wherein the housing has a length to thickness ratio of about 15 or greater and a length to width ratio of about 1.6 or greater.

20. 12. The device of claim 11, wherein the distance between the chest electrodes in the unretracted position is greater than about 10 cm.

21. 12. The device of claim 11, wherein the angle between the arms in the unretracted position is approximately 135 degrees.

22. 1. A method for automatically assessing a patient's risk of an acute cardiac event, comprising: receiving risk assessment information from the patient, the risk assessment information including risk factors, the risk assessment information being received by a processor; storing a pre-existing risk score based on the risk assessment information; receiving a sample electrocardiogram (ECG) from the patient, the sample ECG being automatically recorded by the patient using a three-lead mobile cardiac monitoring device having a first, compact, non-deployed configuration and a second, deployed configuration, and receiving a current symptom indication from the patient; determining, by the processor, an ECG risk score from the sample ECG and the reference ECG, and a chest pain risk score based on the current symptom indication, and determining a post-test risk score using the ECG risk score, the pre-existing risk score, and the chest pain risk score; presenting a diagnostic report and patient action instructions to the patient based on the post-test risk score; A method that encompasses

23. 23. The method of claim 22, further comprising deploying the three-lead mobile cardiac monitoring device from the first compact, undeployed configuration to the second deployed configuration.

24. 23. The method of claim 22, further comprising receiving the reference ECG from the patient with the processor at least 24 hours prior to receiving the sample ECG, the patient obtaining the reference ECG using the handheld device.

25. 23. The method of claim 22, further comprising: said risk factors including age, total cholesterol, HDL, systolic blood pressure, diabetes mellitus status, and current smoking status.

26. 23. The method of claim 22, wherein the existing risk score based on the risk assessment information comprises calculating a weighted sum of the risk factors.

27. 23. The method of claim 22, wherein receiving the sample ECG from the patient comprises the patient using the three-lead mobile cardiac monitoring device having a first compact, undeployed configuration and a second deployed configuration, the handheld device having at least four electrodes acquiring three substantially orthogonal leads.

28. 23. The method of claim 22, wherein receiving the current symptom indication from the patient comprises selecting the current symptom indication from a predefined list of symptoms selectable on the handheld device.

29. 30. The method of claim 28, wherein the selecting comprises selecting the current symptom indication from a user interface of the handheld device.

30. 23. The method of claim 22, wherein determining the ECG risk score comprises indicating risk as high (H), medium (I), or low (L).

31. 23. The method of claim 22, wherein determining the chest pain risk score comprises indicating a risk that is high (H), medium (I), or low (L).

32. 23. The method of claim 22, wherein determining the post-test risk score comprises applying a look-up table indexed by the ECG risk score, the chest pain risk score, and a pre-existing risk score.

33. 23. The method of claim 22, wherein the steps of accepting the sample ECG and the current symptom indication are repeated prior to determining the ECG risk score.

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