Method and system for generating a standard 12-lead ECG

Abstract

A computer-implemented method and system for generating a standard 12-lead ECG is disclosed, the standard 12-lead ECG being formed from three standard limb leads I, II, III, three standard augmented limb leads aVR, aVL, aVF, and six standard precordial leads V1 to V6 from fifteen asynchronous leads, the fifteen asynchronous leads being sequentially acquired by a single-lead electronic device having only two electrodes. The sequentially acquired leads include three acquired limb leads I, II, and III, and twelve acquired arm-based chest leads CR1-CR6 and CL1-CL6. Each pair of acquired leads CRi and Cli among the acquired leads CR1-CR6 and CL1-CL6 represents the acquired voltage difference between the right arm and the left arm and the corresponding common chest position Ci associated with the standard precordial lead Vi.

Description

Technical Field

[0001] The present inventive concept relates to generating a standard 12 - lead electrocardiogram (ECG). More specifically, the present inventive concept relates to a method and system for generating a standard 12 - lead ECG using sequentially acquired leads.

[0002] Background

[0003] The electrical activity of the heart can be measured as the time - varying voltage between two electrodes positioned on the body surface. The waveform of the time - varying voltage from two electrodes is called a lead. In the ECG literature, the term "lead (wire)" is sometimes also incorrectly used for an electrode or a wire, but the correct meaning of the term "lead" is the actual time - varying voltage waveform measured between two electrodes. The term "lead" is also used for leads calculated from measured or acquired leads.

[0004] In "Recommendations for the Standardization and Interpretation of the Electrocardiogram" (pages 1306 - 1324, March 13, 2007, American Heart Association (AHA)), Paul Kligfield et al. presented a statement on the standardization of 12 - lead ECG. In the present disclosure, the standards presented in this document will be referred to as the "AHA standards". As used in the present disclosure, the term "standard 12 - lead ECG" should be interpreted as a 12 - lead ECG according to the AHA standards. As used herein, the term "twelve standard leads" should be interpreted as the twelve leads of a standard 12 - lead ECG.

[0005] The standard 12 - lead ECG consists of twelve standard leads, including: three limb leads (I, II, and III), three augmented limb leads (aVR, aVL, and aVF), and six precordial leads (V1, V2, V3, V4, V5, and V6).

[0006] In modern electrocardiographs (also known as ECG machines), the standard 12-lead ECG is typically created or generated using ten electrodes that are connected to the electrocardiograph and placed at predefined locations on the body surface. Four of the ten electrodes are placed on the limbs. Six of the ten electrodes are placed on the chest above the heart, at predefined or standard chest electrode positions. The electrical signals acquired simultaneously by the ten electrodes are amplified and processed (including calculating certain leads) to generate 12-channel ECG data. The resulting twelve channels or leads are commonly referred to as, on the one hand, the six limb leads (I, II, III, aVR, aVL, aVF) that represent the electrical activity in the frontal plane, and on the other hand, the six precordial leads (V1, V2, V3, V4, V5, V6) that represent the electrical activity approximately corresponding to the horizontal plane.

[0007] Thus, using ten electrodes attached to the machine via ten cables, different combinations of simultaneous measurements between ten standard electrode positions on the body (right arm (RA), left arm (LA), left leg (LL), and right leg (RL), and chest 1 to chest 6 (C1-C6)) are used to simultaneously measure the leads initially recorded or acquired by a conventional 12-lead electrocardiograph. The terms RA, LA, LL, RL, and C1-C6 can refer to both the electrode positions and the actual ten electrodes. These ten standard electrode positions form part of the AHA standard. In the present disclosure, the limb electrode positions RA, LA, LL, RL can refer to any position on the corresponding limb, not necessarily the positions on the wrists and ankles. Figure 1 It is shown that the three limb electrodes RA, LA, and LL form a triangle (Einthoven triangle). The electrode at the right leg RL is used as a ground electrode and actually contributes nothing to any of the leads. Figure 3 Six predefined chest electrode positions C1-C6 are shown.

[0008] In a standard 12-lead ECG machine, all ten electrodes are typically wired to the machine and all leads are measured simultaneously. Thus, the potential of the heart can be measured simultaneously from twelve different angles and recorded over a period of time (usually 10 seconds or longer), where each angle corresponds to one of the twelve standard leads respectively. Thus, by definition, the simultaneously measured leads obtained by a modern ECG machine will all be mutually time-aligned or "synchronized". This is relevant because the three augmented limb leads aVR, aVL, aVF, and the six precordial leads V1-V6, which all form part of the standard 12-lead ECG, are continuously calculated during acquisition based on the measured leads.

[0009] In recent years, various types and designs of portable or wearable single-lead electronic devices that use only two electrodes have been developed, where typically only one lead (limb lead I) is measured and recorded. Some of these prior art electronic devices are in the form of smartwatches, smartphones, etc., while others are in the form of dedicated single-lead ECG devices. These two electrodes can be integrated in such a single-lead device, or they can be connected to the electronic device either wired or wirelessly. Although such single-lead ECG devices can be used to monitor and detect certain conditions, such as arrhythmias, a single-lead ECG device that produces a single lead has only limited use for cardiac diagnosis.

[0010] There are several ECG devices based on prior art single-lead smartwatches from different manufacturers, including the Apple Watch Series 4, 5, and (Apple Inc., Cupertino, CA, USA), which allows a single-lead ECG (usually limb lead I) to be recorded. For example, using the Apple Watch, limb lead I can be measured by recording the voltage difference over time, for example, between the right index finger touching the watch crown and the left arm wrist touching the back of the watch, which corresponds to Einthoven's limb lead I. The ECG recording can be activated by the patient / user, and thereafter a pdf document of the single-lead ECG can be generated using the associated app for subsequent printing and / or forwarding for diagnostic evaluation.

[0011] In recent years, there have been several attempts to use single-lead ECG devices to generate various types of multi-lead ECGs. In particular, a great deal of effort has been made to reproduce or "synthesize" a standard 12-lead ECG similar to a synchronously recorded standard 12-lead ECG, but using a single-lead ECG device with only two electrodes and sequential lead acquisition, which results in asynchronously acquired leads. So far, this effort has not been successful and has only produced other types of multi-lead ECGs that are different from the standard 12-lead ECG and are not suitable for most diagnostic uses.

[0012] The article "Single-Lead ECG Recordings Including Einthoven and Wilson Leads by a Smartwatch: A New Era of Patient Directed Early ECG Differential Diagnosis of Cardiac Diseases?" by Alexander Samol, Kristina Bischof, Blerim Luani, Dan Pascut, Marcus Wiemer, and Sven Kaese (Sensors 2019, 19, 4377) discloses the results of obtaining multiple leads sequentially using an Apple Watch. The method proposed in this study cannot generate a standard 12-lead ECG. In particular, the six standard precordial leads V1-V6 are not generated. Instead, non-standard precordial leads are recorded by placing one hand on the wrist of the other hand, bringing both hands and forearms into contact with the chest, and sequentially holding the watch at three chest electrode positions C1, C4, and C6, thus recording three leads referred to in this article as "Wilson-like" chest leads. These three non-standard leads are different from the six standard precordial leads V1-V6 and cannot be used to generate a standard 12-lead ECG for reliable diagnosis.

[0013] Another example of a prior art single-lead ECG device is a smartwatch that is commercially available from AliveCor, Inc. (USA). Patents describing representative technologies include US 9,986,925 B2 and US 9,833,158 B2.

[0014] In "Simultaneous 12-lead Electrocardiogram Synthesis using a Single-Lead ECG Signal: Application to Handheld ECG Devices" by Kahkashan Afrin, Parikshit Verma, Sanjay S. Srivatsa, and Satish T. S. Bukkapatnam, published on November 20, 2018, the disadvantages and unsuccessful results of prior art attempts to use single-lead ECG devices to create multi-lead ECGs are also discussed. As described in this article, many attempts have been made to derive or "synthesize" a standard 12-lead ECG from a single-lead portable device by sequentially recording signals from a single-lead (two-electrode) device, one acquisition or lead at a time. By The results obtained with the company's smartwatch are described in the article as follows: "Vectorcardiography (VCG) analysis suggests that the cardiac axis synthesized from these earlier attempts deviates considerably from that estimated from 12-lead and / or Frank lead measurements." Thus, by using VCG analysis, it has been demonstrated that previous attempts, such as those used by the company, produce an ECG that deviates significantly from the synchronized standard 12-lead ECG and is thus clinically unsatisfactory. In addition, the different method proposed in the article has the drawback that it requires the initial recording of a simultaneous standard synchronized 12-lead ECG using a conventional 12-lead ECG machine. Furthermore, in order to run the proposed method, the previously acquired and simultaneously recorded standard 12-lead ECG must be uploaded to a cloud-based server. When a single-lead ECG is subsequently recorded, the previously acquired "true" standard 12-lead ECG is used to synthesize the 11 missing lead signals at that time.

[0015] Therefore, there is a need to generate or "synthesize" a standard 12-lead ECG formed by twelve standard ECG leads from sequentially acquired leads using a single-lead ECG device (such as by using a portable or wearable single-lead electronic device) without the need to record any standard synchronized 12-lead ECG. Summary of the Invention

[0017] In view of the above, the object of the present invention concept is to provide a method and system in which the above disadvantages of the prior art are solved.

[0018] According to a first aspect of the present invention concept, there is provided a method for generating a standard 12-lead ECG formed by three standard limb leads I, II, III, three standard augmented limb leads aVR, aVL, aVF, and six standard precordial leads V1 to V6 from fifteen asynchronous, sequentially acquired leads, the fifteen asynchronous, sequentially acquired leads including three acquired limb leads I, II, and III (referred to as acquired leads I-III), and twelve acquired arm-based chest leads CR1-CR6 and CL1-CL6 (referred to as acquired leads CR1-CR6 and CL1-CL6);

[0019] Wherein, for an integer i equal to 1 to 6, each pair of the acquired leads CR1-CR6 and CL1-CL6, i.e., the acquired leads CRi and CLi, represents the acquired voltage difference between the right arm and the left arm and the corresponding common chest position Ci associated with the standard precordial lead Vi.

[0020] The method includes:

[0021] According to the acquired leads I-III, by using the equation: Lead II - Lead I = Lead III, create time-aligned limb leads I, II, and III (referred to as time-aligned leads I-III).

[0022] According to the time-aligned leads I-III, calculate three time-aligned augmented limb leads aVR, aVL, and aVF.

[0023] For an integer i equal to 1 to 6, perform one of (a) and (b):

[0024] (a) Create a time-aligned arm-based chest lead CRi (referred to as time-aligned lead CRi) by time-aligning the acquired lead CRi with the acquired lead I, such that the calculated difference CRi - I representing the calculated arm-based chest lead CLi (referred to as the calculated lead CLi) has the best consistency with the acquired lead CLi.

[0025] (b) Create a time-aligned, acquired arm-based chest lead CLi (referred to as time-aligned lead CLi) by time-aligning the acquired lead CLi with the acquired lead I, such that the calculated sum CLi + I representing the calculated arm-based chest lead CRi (referred to as the calculated lead CRi) has the best consistency with the acquired lead CRi.

[0026] And

[0027] For an integer i equal to 1 to 6, calculate a time-aligned precordial lead Vi based on one of the time-aligned lead I, the time-aligned lead II, and the time-aligned lead III, and one of the time-aligned lead CRi and the time-aligned lead CLi, to form time-aligned precordial leads V1-V6.

[0028] Wherein the time-aligned leads I-III, the time-aligned augmented limb leads aVR, aVL, and aVF, and the time-aligned precordial leads V1-V6 together form a standard 12-lead ECG.

[0029] The concept of the present invention enables the generation of a standard 12-lead ECG from sequentially acquired leads, including twelve standard leads (specifically including six standard precordial leads V1-V6). In particular, the concept of the present invention enables the generation of all twelve standard leads I, II, III, aVR, aVL, aVF, and V1-V6 of a standard 12-lead ECG with extremely high precision from a plurality of sequentially acquired or "asynchronous" ECG signals. In its broadest aspect, the method according to the concept of the present invention includes actions for generating a standard 12-lead ECG performed on fifteen specified asynchronously acquired leads. According to some embodiments, the method according to the concept of the present invention further includes one or more actions of sequentially acquiring or recording leads.

[0030] The concept of the present invention enables the use of a single-lead electronic device having only two electrodes, and during the sequential acquisition of the fifteen leads, the positions of the two electrodes on the subject's body are sequentially changed to generate a standard 12-lead ECG, including all twelve standard leads. Such a single-lead (two-electrode) electronic device can in particular be a portable or wearable electronic device, such as a smartwatch, a smartphone, a tablet computer, or a dedicated electronic ECG device. The two electrodes can be integrated in the electronic device, such as integrated in a smartwatch. One or both electrodes can also be electrodes that are wired or wirelessly connected to the electronic device.

[0031] A particular advantage obtained by the concept of the present invention over the above-mentioned prior art relates to the precordial leads V1-V6. When recording a conventional synchronous 12-lead ECG using an ECG machine having ten electrodes, during the ECG recording, the precordial leads are continuously "calculated" by subtracting the potential at the so-called Wilson central terminal (WCT) from the potentials at each of the chest electrodes C1-C6. As mentioned in the AHA standard, the WCT is the average potential of the three limb potentials RA, LA, and LL. In prior art attempts using a single-lead device, the right arm and the left arm have been used as a reference instead of the WCT. The measured PQRST waveforms of the measured CR and CL leads are not the same as the PQRST waveforms of the corresponding calculated precordial leads recorded using the WCT reference. Since the concept of the present invention generates true precordial leads V1-V6, a true standard 12-lead ECG can be generated from the sequentially acquired leads.

[0032] Thus, the insight into the concept of the present invention is that by sequentially acquiring fifteen specific leads and performing time alignment and calculations on the fifteen sequentially acquired leads, six standard precordial leads V1-V6 can be specifically created based on the sequentially acquired leads. The substantial insight is that considering the standard precordial leads are defined as Vi = Ci - WCT, where WCT = 1 / 3(RA + LA + LL). It is not possible to place a single electrode at WCT as it represents a "virtual" electrode calculated based on RA, LA, and LL. In a conventional 10-electrode ECG machine, during synchronous recording, WCT can be continuously calculated by averaging three simultaneous measurements from electrodes RA, LA, and LL to continuously give the average potential of the body.

[0033] Nine standard leads aVR, aVL, aVF and V1, V2, V3, V4, V5 and V6 are defined as the voltage between a given physical electrode and a virtual electrode that is calculated based on simultaneous measurements of combinations of physical electrodes. One insight of the concept of the present invention is that in order to correctly measure aVR, aVL, aVF, V1, V2, V3, V4, V5 and V6, all sequentially acquired signals must be very accurately time-aligned so that correct calculations can be performed based on the acquired leads.

[0034] Another insight of the concept of the present invention is that by performing the method of the present invention on fifteen specific and sequentially acquired leads (i.e., 3 more leads than in a standard ECG and many more acquired leads than in a conventional 10-electrode electrocardiograph with simultaneous acquisition), twelve time-aligned standard leads of a standard 12-lead ECG can be created. As a comparison, many digital 10-electrode electrocardiographs today only simultaneously record independent information on eight channels, where four limb leads are derived from two others, which will be described in detail below. By performing the method of the present invention on fifteen specific asynchronous, sequentially acquired leads, specific redundant information in the acquired leads is available, enabling the generation of twelve standard leads.

[0035] Therefore, the concept of the present invention and its solution, namely how to reproduce a correct standard 12-lead ECG using only two electrodes and sequential measurements, and in particular that the standard 12-lead ECG includes standard precordial leads V1-V6 instead of using any directly measured "quasi-chest leads" as a substitute for the standard precordial leads V1-V6, includes the insight that by using specific acquired leads that do not form part of the group of twelve "standard leads" and include specific redundant information, and by performing time alignment and calculations based on these non-standard leads in combination with the acquired standard limb leads I-III, all the time alignment and calculations required to obtain all twelve standard leads for generating a standard 12-lead ECG can be performed.

[0036] Another insight of the present invention is that six time-aligned standard precordial leads V1-V6 can be created by performing the method of the present invention on fifteen successively acquired leads, which fifteen successively acquired leads particularly include six arm-based chest leads CR1-CR6 and six arm-based chest leads CL1-C6.

[0037] Definition

[0038] As used herein, the term "lead" will be used for two types of leads: the initially acquired lead, which is measured as the time-varying potential difference between electrode pairs on the body surface; and the lead used for subsequent time alignment, averaging, or calculation, particularly including all twelve standard leads that form the standard 12-lead ECG. For the sake of clarity, the terms "acquired", "time-aligned", "averaged", and "calculated" will be used to specify the "state" of different leads.

[0039] As used herein, the term "standard 12-lead ECG" will be interpreted as the 12-lead ECG as described in the background section above, i.e., including the twelve standard leads I, II, III, aVR, aVL, aVF, and V1-V6. In particular, the expressions "standard 12-lead ECG" and "twelve standard leads" should be interpreted as not including precordial quasi-leads that do not represent the standard precordial leads V1 to V6 or any arm-based chest leads.

[0040] As used herein, the term "single-lead ECG device" or similar terms should be interpreted as a device configured to successively measure or record only one lead at a time (asynchronous measurement), which is contrasted with a device or machine configured to generate the ECG of all twelve standard leads simultaneously using ten electrodes. Thus, the term "single-lead ECG device" is also used to include existing single-lead ECG devices that, if modified by hardware and / or software, will be used to implement the concept of the present invention, i.e., to generate all twelve standard ECG leads of the standard 12-lead ECG, but still generate them by recording one lead at a time in sequence.

[0041] In the concept of the present invention, only two electrodes are needed. These can be placed at the same electrode positions as in a conventional 12-lead ECG. Thus, in this application, the terms RA, LA, and LL, as well as C1-C6, will be used to refer to the corresponding electrode positions rather than the electrodes themselves.

[0042] As used herein, the terms "sequentially acquire", "sequentially record", "sequentially measure", etc. shall be construed as actions where, between each measurement, different electrode position pairs on the body are used, and the corresponding electrical ECG signals are recorded or acquired one after another over time, resulting in asynchronously acquired leads.

[0043] As used herein, the term "electrode" refers to a discrete electrode or electrode assembly configured to measure the potential at a given position on the body surface. Thus, an electrode assembly formed by two or more electrode components or parts is also considered an "electrode".

[0044] As used herein, the term "compute" refers to a process of performing calculations or processing using one or more electronic processing units.

[0045] The action of creating time - aligned leads in a method according to the inventive concept may include averaging each of the fifteen acquired leads to create fifteen corresponding average beat waveforms, and using the average beat waveforms as the acquired leads in the step of creating time - aligned leads I - III and in steps (a) and (b) of creating time - aligned leads CR1 - CR6 and time - aligned leads CL1 - CL6, respectively. In the literature, such average beat waveforms are sometimes also referred to as "averaged complexes". Clearly, such averaging requires recording each acquired lead over a period representing more than one heartbeat. The averaging of each lead can be performed by detecting the maximum deviation of each QRS complex in the lead and using that maximum deviation to align the beats and thereby form an average beat, and including various strategies for excluding arrhythmias or extra beats of different waveform morphologies from the average.

[0046] In some embodiments that include such averaging of the acquired ECG signals to form an average beat waveform, the method may include the following items:

[0047] Time - aligned leads I - III are created according to average beat waveforms I - III and will be in the form of time - aligned average beat waveforms I - III;

[0048] Time - aligned augmented limb leads aVR, aVL, and aVF are computed according to time - aligned leads I - III and will be in the form of time - aligned average beat waveforms;

[0049] In steps (a) and (b), each of the acquired limb-based leads CRi and CLi is averaged to respectively form associated average beat waveforms CRi and CLi, and the relevant average beat waveforms CRi and CLi are used to perform the time alignment in steps (a) and (b), wherein the resulting time-aligned leads CR1-CR6 and CL1-CL6 will be in the form of time-aligned average beat waveforms; and

[0050] The standard precordial leads V1-V6 are calculated based on the above time-aligned average beat waveforms, and the calculated V1-V6 will also be in the form of time-aligned average beat waveforms.

[0051] In some embodiments that include such averaging of the acquired ECG signals to form average beat waveforms, the initially acquired raw data can be eliminated by the subsequent averaging. However, it may be preferred to save all or at least some of the sequentially acquired raw data. It can be used for quality control. It can also be used by healthcare professionals or algorithms to evaluate the heart rhythm. For some arrhythmia conditions, the morphology of the beat waveform is not decisive, but rather the rhythm of the waveform change over time.

[0052] According to an embodiment, the time alignment in step (a) is performed by iteratively moving the acquired lead CRi and the acquired lead I relative to each other to achieve the best consistency between the difference CRi-I and the acquired lead CLi; and the time alignment in step (b) is performed by iteratively moving the acquired lead CLi and the acquired lead I relative to each other to achieve the best consistency between the sum CLi+I and the acquired lead CRi.

[0053] According to an embodiment, the act of creating time-aligned leads I-III based on the acquired leads I-III includes using the third acquired lead among the acquired leads I-III as a reference to time-align the first acquired lead among the acquired leads I-III with the second acquired lead among the acquired leads I-III. As a non-limiting example, using the acquired lead III as a reference, the acquired lead II can be time-aligned with the acquired lead I. The time alignment can be performed such that the calculated difference II-I representing the calculated lead III has the best consistency with the acquired lead III. The calculated lead III can be used as the time-aligned lead III. In some embodiments, the time alignment can be performed by iteratively moving the first acquired lead and the second acquired lead relative to each other to achieve the best consistency. In other embodiments, the acquired leads II and III, or the acquired leads I and III are used as the first acquired lead and the second acquired lead for time alignment.

[0054] The various actions or steps of the method according to the inventive concept can be performed in any order and still result in the twelve standard leads together forming a standard 12-lead ECG.

[0055] According to some embodiments, a time-aligned Lead I can be created prior to performing step (a) or step (b) respectively. The time alignment in step (a) or (b) can then be performed using the time-aligned Lead I respectively. Alternatively, it can also be started by time-aligning all or some of the acquired arm-based chest leads with the acquired Lead I and then performing the action of creating time-aligned Leads I-III. These and other possible variations will be further discussed below.

[0056] Regarding the order of the actions or steps of the method according to the inventive concept, it can also be noted that when all time-aligned leads are available, the calculation of the six time-aligned precordial leads V1-V6 can be performed as a last step, or alternatively, the calculation for each precordial lead Vi can be performed once the time-aligned leads required for calculating the specific precordial lead Vi are available.

[0057] For each integer i equal to 1 to 6, method steps (a) and (b) of the method according to the inventive method are alternatives to each other because either the time-aligned Lead CRi or the time-aligned Lead CLi can be used in the calculation of the associated time-aligned standard precordial lead Vi. In some embodiments, only step (a) is used to create six time-aligned arm-based chest leads CR1-CR6 without using step (b), and six time-aligned arm-based chest leads CL1-CL6 are not created. In some embodiments, only step (b) is used to create six time-aligned arm-based chest leads CL1-CL6 without using step (a), and six time-aligned arm-based chest leads CR1-CR6 are not created. Combinations of these embodiments are also possible, and in some embodiments, steps (a) and (b) are performed for each i equal to 1 to 6.

[0058] In some embodiments, the acquisition of the twelve arm-based chest leads CR1-CR6 and CL1-CL6 can be performed in pairs: for each integer i equal to 1 to 6, the acquired Lead CRi and the acquired Lead CLi are measured one after another in any order while keeping one electrode positioned at the associated common chest position Ci, so that each pair of leads CRi CLi is measured directly after each other in any order without moving the chest electrode between the two measurements.

[0059] Redundancy in the information present in the fifteen acquired leads can be utilized to obtain additional advantages, including noise reduction and / or reduced acquisition time. Such embodiments can include averaging each time-aligned lead with a computed version of the same lead to create an associated averaged time-aligned lead, thereby taking advantage of as much of the available redundant information as possible. Details and examples of such averaging techniques will be given in the detailed description below.

[0060] According to an embodiment, a method according to the method of the present invention can also include creating a vectorcardiogram VCG by mathematically deriving the so-called Frank leads X, Y, and Z from the time-aligned leads I and II and the time-aligned precordial leads V1-V6.

[0061] An important method of evaluating an ECG can be to evaluate the VCG. The VCG includes acquiring the leads X, Y, and Z according to Frank, which represent three orthogonal spatial directions of the body (left-right, up-down, front-back). Acquisition of the Frank leads X, Y, and Z is rarely performed, but the Frank leads X, Y, and Z can be mathematically derived from a standard 12-lead ECG, more specifically, from the standard limb leads I and II and the standard precordial leads V1-V6. Further information can be found in Kors JA, van Herpen G, Sittig AC, van Bemmel JH in the European Heart Journal (Eur Heart J), "Reconstruction of the Frank vectorcardiogram from standard electrocardiographic leads: diagnostic comparison of different methods." (December 1990; 11(12): 1083-92).

[0062] The study showed that the derived VCG had very good agreement with the Frank X, Y, and Z leads. Regression analysis was used for the derivation to determine the optimal coefficients to multiply with the limb leads I, II, and the precordial leads V1-V6 in order to derive the leads X, Y, and Z. As an example, the Frank lead X can be calculated using the reconstruction matrix according to Kors as follows:

[0063] X = 0.38I – 0.07II – 0.13V1 + 0.05V2 – 0.01V3 + 0.14V4 + 0.06V5 + 0.54V6

[0064] When creating Frank leads according to this embodiment of the present invention, since they are created by the method of the present invention, the eight standard leads (I, II, V1-V6) used in the above calculations are all time-aligned and can thus be used to mathematically derive the Frank leads X, Y, and Z to produce a correct VCG. VCG analysis also requires simultaneous accuracy in time-aligning the entire 12-lead ECG.

[0065] The VCG obtained through this embodiment can optionally be used for clinical diagnosis by algorithms or by visual inspection of the VCG or numerical measurements derived from the VCG by healthcare professionals. However, the obtained VCG can also be advantageously used in the form of the derived Frank leads X, Y, and Z for evaluation by advanced diagnostic algorithms, since Frank leads have been shown to be particularly advantageous for such diagnostic algorithms. In addition, as will be demonstrated below, the VCG plots derived from the concepts of the present invention can be used to clearly demonstrate a high degree of consistency with the simultaneously recorded standard 12-lead ECG.

[0066] According to a second aspect of the concepts of the present invention, there is provided a system for generating a standard 12-lead ECG formed by three standard limb leads I, II, III, three standard augmented limb leads aVR, aVL, aVF, and six standard precordial leads V1 to V6, the system comprising:

[0067] Two electrodes;

[0068] At least one processing unit configured to perform the following actions:

[0069] When the two electrodes are sequentially moved to different positions on the body of a subject, sequentially acquire fifteen ECG leads between the two electrodes, including three acquired limb leads I, II, and III (referred to as acquired leads I-III), and twelve acquired arm-based chest leads CR1-CR6 and CL1-CL6 (referred to as acquired leads CR1-CR6 and CL1-CL6), wherein for an integer i equal to 1 to 6, each pair of acquired leads CRi and CLi in the acquired leads CR1-CR6 and CL1-CL6 represents the acquired voltage difference between the right arm and the left arm and the common chest position Ci associated with the corresponding standard precordial lead Vi;

[0070] Create three time-aligned limb leads I, II, and III (referred to as time-aligned leads I-III) according to the acquired leads I-III by using the equation: lead II - lead I = lead III; calculate three time-aligned augmented limb leads aVR, aVL, and aVF based on the time-aligned leads I-III;

[0071] For an integer i equal to 1 to 6,

[0072] (a) Create a time-aligned arm-based chest lead CRi (referred to as the time-aligned lead CRi) by time-aligning the acquired lead CRi with the acquired lead I such that the calculated difference CRi - I representing the calculated arm-based chest lead CLi has the best consistency with the acquired lead CLi, or

[0073] (b) Create a time-aligned acquired arm-based chest lead CLi (referred to as the time-aligned lead CLi) by time-aligning the acquired lead CLi with the acquired lead I such that the calculated sum CLi + I representing the calculated arm-based chest lead CRi has the best consistency with the acquired lead CRi;

[0074] And for an integer i equal to 1 to 6, calculate a time-aligned precordial lead Vi based on one of the time-aligned lead I, time-aligned lead II, and time-aligned lead III, and one of the time-aligned lead CRi and time-aligned lead CLi to form time-aligned precordial leads V1 - V6;

[0075] Wherein the time-aligned leads I - III, time-aligned augmented limb leads aVR, aVL, and aVF, and time-aligned precordial leads V1 - V6 together form a standard 12-lead ECG.

[0076] In an embodiment, the system can be incorporated into a portable or wearable single-lead electronic device that includes the two electrodes and includes at least one processing unit configured to perform the actions. In some embodiments, all actions related to sequentially acquiring fifteen leads and thereby generating a standard 12-lead ECG can be performed using only such an electronic device without any other external devices. The electronic device can be a smartwatch, smartphone, dedicated ECG device, etc. The two electrodes can be integrated into the electronic device, for example, formed on the exterior of the smartwatch, or one or both electrodes are formed as electrodes separate from the electronic device and wired or wirelessly connected to the electronic device. In some embodiments, the electronic device can communicate with at least one external device such as a smartphone, tablet, or computer for specific functions such as providing a user interface where the user can give and receive instructions, and for displaying the generated standard 12-lead ECG.

[0077] In an alternative embodiment, the system may be partially incorporated into such a portable or wearable electronic device including two electrodes and partially incorporated into at least one external device, where the electronic device and the at least one external device are configured to communicate with each other. In such an embodiment, the at least one external device may include a smart phone, a tablet computer, a computer, etc., and / or at least one external device including at least one server (such as a cloud server).

[0078] The at least one processing unit may be a central processing unit (CPU), which may execute instructions of one or more computer programs to perform the actions of the method of the present invention and optionally also control lead acquisition, including receiving user instructions and providing user instructions. Alternatively, the at least one processing unit may be implemented as firmware or as a specially designed processing unit. In the broadest aspect of the inventive concept, the at least one processing unit may be located anywhere, such as in the "cloud".

[0079] The system according to the inventive concept may be configured to perform the actions of the method as defined in any one of the method claims.

[0080] The advantages and embodiments discussed above in connection with the method of the present invention also apply to the system according to the inventive concept.

[0081] According to a third aspect of the inventive concept, there is provided a non-transitory computer-readable recording medium on which a program executable on a processing unit having processing capabilities has been recorded, where the program includes a program code portion that, when executed on an electronic device, is configured to perform the method according to any one of the method claims.

[0082] The program may implement the method in at least one processing unit, and the at least one processing unit may be a dedicated processing unit for performing the method or a general-purpose processing unit capable of performing the method based on a computer program product.

[0083] The program product may be provided on a computer-readable medium (such as any computer-readable medium capable of storing computer-readable instructions) provided with computer-readable instructions. However, the program may also or alternatively be downloaded from a server such that the program may be provided as a signal carrying the computer-readable instructions being downloaded.

[0084] Preferred embodiments of the inventive concept are set forth in the dependent claims. Brief Description of the Drawings

[0086] The inventive concept, some non-limiting embodiments, and other advantages of the inventive concept will now be described with reference to the drawings, where:[[]]END]]

[0087] Figure 1 Shows limb leads I-III.

[0088] Figure 2 Shows augmented limb leads aVR, aVL, aVF.

[0089] Figure 3 Shows standard chest electrodes C1-C6.

[0090] Figure 4 Shows a smartwatch positioned for obtaining limb leads.

[0091] Figure 5 and Figure 6 Shows a smartwatch positioned for obtaining two arm-based chest leads.

[0092] Figure 7 Shows the time alignment of limb leads I-III.

[0093] Figure 8 Shows the time alignment of arm-based chest leads CR1-CR6 and CL1-CL6.

[0094] Figures 9a - 9c Shows fifteen serial raw data acquisitions and corresponding average beat waveforms.

[0095] Figure 10 Shows the time alignment effect.

[0096] Figures 11a - 11c Shows waveforms demonstrating the accuracy of the inventive concept.

[0097] Figure 12 Shows a standard 12-lead ECG generated by an embodiment of the present invention.

[0098] Figure 13 Is a three-dimensional VCG diagram generated by an embodiment of the present invention.

[0099] Figure 14 Is a flowchart showing the operations of an embodiment of the present invention.

[0100] Figure 15 Is a flowchart showing the operations of an embodiment of the present invention.

[0101] Figure 16 Is a schematic diagram of an embodiment of a system according to the inventive concept.

[0102] Detailed description

[0103] Figure 1Shows the three standard limb electrode positions RA, LA, and LL, and also shows how the three standard limb leads I-III are measured between these electrodes. According to the AHA standard, the measurements of limb leads I-III are as follows:

[0104] I = potential difference LA - RA (1)

[0105] II = potential difference LL - RA (2)

[0106] III = potential difference LL - LA (3)

[0107] Figure 2 Shows the three standard augmented limb leads aVF, aVL, and aVR. When measuring the three limb leads I-III between physical electrodes, each of the augmented limb leads aVR, aVL, and aVF is measured between a relevant one of the three electrodes RA, LA, and LL and a relevant virtual electrode representing the average of the two opposite electrodes (referred to as the "Goldberger central terminal"). Using the above equations (1)-(3) for simplification, the augmented limb leads aVR, aVL, and aVF are calculated according to the AHA standard as follows:

[0108] aVF = LL - (LA + RA) / 2 = (II + III) / 2 (4)

[0109] aVL = LA - (RA + LL) / 2 = (I - III) / 2 (5)

[0110] aVR = RA - (LA + LL) / 2 = -(I + II) / 2 (6)

[0111] Figure 3 Shows the six standard chest electrode positions C1-C6 for measuring the six standard precordial leads V1-V6 in a standard 12-lead ECG. As described above for the augmented limb leads, each of the six standard precordial leads V1-V6 is measured between a relevant one of the physical electrodes C1-C6 and a virtual electrode. For the precordial leads V1-V6, a common virtual electrode (referred to as the Wilson central terminal WCT) is used, which is obtained by calculating the average of the three measured potentials at RA, LA, and LL:

[0112] WCT = (RA + LA + LL) / 3 (7)

[0113] Each standard precordial lead Vi (i = 1 to 6) is calculated as follows:

[0114] Vi = potential difference Ci - WCT (8)

[0115] Thus, nine of the twelve standard leads that form a standard 12-lead ECG are calculated based on virtual electrodes, which in turn are calculated based on two or more measured potentials. This fact represents a significant challenge when using a single-lead device, as any calculations must be performed on leads that are time-synchronized. When only asynchronous, sequentially acquired data is available, time alignment becomes crucial for obtaining clinically reliable results, as the calculations require synchronized data. In a conventional synchronous ECG machine, this problem does not occur, as all calculations can be performed continuously within the recording period of the synchronized measurement signals. As will be demonstrated below, obtaining sufficiently time-synchronized signals from asynchronous ECG signals is extremely challenging. Even the slightest incorrect time shift, i.e., time misalignment, can have a significant impact, resulting in an incorrect, potentially misleading, and useless ECG. In prior art attempts to generate a multi-lead ECG from asynchronous sequential data, the proposed methods have been used to avoid challenges, particularly regarding the standard precordial leads V1-V6 and the WCT, and instead use directly measured (non-calculated) and fewer non-standard leads in the ECG. The biases resulting from these solutions were discussed in the above VCG analysis.

[0116] Part of the inventive concept is based on the fact that each of the precordial leads V1-V6 can be represented by a measurement of the potential difference between the corresponding chest electrode Ci and the arm electrodes:

[0117] For example, the standard precordial lead V1 can be calculated as:

[0118] V1 = C1 - WCT = C1 - (LA + LL + RA) / 3 = (3*C1 - LA - LL - RA) / 3 =

[0119] (3*(C1 - RA) - (LA - RA) - (LL - RA)) / 3 =

[0120] (C1 - RA) - ((LA - RA) + (LL - RA)) / 3 = CR1 - (I + II) / 3

[0121] where

[0122] CR1 = C1 - RA

[0123] Thus, for each precordial lead Vi of the standard precordial leads V1 to V6, where i is an integer equal to 1 to 6, can be calculated based on the measured leads CRi, I, and II as follows:

[0124] Vi = CRi - (I + II) / 3 (9)

[0125] where

[0126] CRi = Ci - RA (10)

[0127] In the present disclosure, the leads CR1 - CR6 measured between RA and C1 - C6 are referred to as "arm - based chest leads". The leads CL1 - CL6 measured between LA and C1 - C6 are also referred to as "arm - based chest leads".

[0128] The concept of the present invention is partly based on the insight that the standard precordial leads V1 - V6 of a standard 12 - lead ECG can be "synthesized" from successively acquired asynchronous leads using (9) and (10) above, provided that the three acquired leads CRi, I, and II can be accurately time - aligned.

[0129] However, attempting to time - align the acquired ECG signals using time - alignment of the average beats based on the peaks of the QRS complexes will fail. The peaks of the QRS complexes cannot be used as a time - alignment time reference because the QRS peaks occur at different time points in different leads. Therefore, using the peaks of the QRS complexes will result in incorrect time - alignment and thus incorrect calculation of the precordial leads V1 - V6.

[0130] The concept of the present invention is also partly based on the insight that the standard precordial leads V1 - V6 of a standard 12 - lead ECG can be "synthesized" from successively acquired asynchronous leads if information redundancy from non - standard leads is used, namely, information redundancy from the successively acquired arm - based chest leads CR1 - CR6 and the successively acquired arm - based chest leads CL1 - CL6.

[0131] The concept of the present invention relates to time - alignment actions and calculation actions. These actions can be performed in different orders. Now reference will be made to Figures 4 to 8 and Figures 9a - 9c A first non - limiting embodiment will be described, in which successive acquisitions are performed by using a single - lead electronic device (here in the form of a smartwatch 10) that includes two electrodes, a display, a processing unit, and a program (app) that, when executed on the processing unit, is configured to perform the actions described below. The first electrode is located on the back of the smartwatch, and the second electrode is formed by the crown 12, and / or the frame, and / or some other visibly touchable part of the smartwatch 10. All variants of the second electrode are collectively referred to as the "crown" herein.

[0132] Fifteen specific leads are successively acquired: three limb leads I - III, six arm - based chest leads CR1 - CR6, and six arm - based chest leads CL1 - CL6. Figures 9a - 9cFifteen waveforms recorded from a subject over a 15 - second period are shown on the right. This is the raw data obtained fifteen times in sequence from a representative subject, which, according to the inventive concept, requires time alignment and calculation to form a standard 12 - lead ECG. The small circles show the detection of the maximum deviation of the QRS complex, which is used to align the recordings to form the Figures 9a - 9c average beat waveform shown on the left in

[0133] In this non - limiting embodiment, as shown in Figure 4 and Figure 7 , initially the limb leads I - III are recorded. The smartwatch 10 is initially attached to or held on the subject's left wrist, and the first electrode on the back of the smartwatch contacts the electrode position LA. The right index finger touches the crown 12, thus closing the circuit. The second electrode position corresponds to the electrode position RA. The limb lead I (LA - RA) is recorded over a period of time that represents at least one heartbeat, preferably multiple heartbeats for subsequent averaging. In the illustrated case, all leads are recorded over a 15 - second period. Thereafter, by holding the smartwatch 10 such that its back electrodes contact the electrode positions LA and LL respectively, the limb lead II and the limb lead III are recorded. To measure lead II (LL - RA), the right hand remains in contact with the crown 12, and to measure lead III (LL - LA), the left hand remains in contact with the crown 12. The electrode position LL can be at any position on the left leg (ankle, knee) or at the lower left side of the abdomen, as shown by the dashed electrode position in Figure 7 . In this way, three sequentially acquired limb leads I - III are obtained and stored in the memory of the smartwatch 10. Figure 9a The right side of

[0134] shows the sequentially acquired data. Figure 5 , Figure 6 and Figure 8 Subsequently, as shown in Figure 5 , twelve arm - based chest leads CR1 - CR6 and CL1 - CL6 are measured in sequence. Referring to Figure 5 , the user initially holds the smartwatch 10 such that the back electrode contacts the chest at the electrode position C1, and the right hand contacts the crown 12 (the second electrode) to close the circuit. At this position, the lead CR1 = C1 - RA ( Figure 8 ) is recorded. Thereafter, while holding the smartwatch 10 in the same position as shown in Figure 6 , the user in turn uses the left hand to contact the crown 12 to record the lead CL1 between the electrode LA and C1 ( Figure 8)。Repeat this process to record all lead pairs CRi and Cli in sequence. In this way, the twelve arm-based chest leads CR1-CR6 and CL1-CL6 are recorded in sequence and stored in the memory of the smartwatch 10. Figure 9b and Figure 9c The recorded waveforms are shown on the right side of.

[0135] To optimize the accuracy of the time alignment and calculations to be performed, it is beneficial to create an average beat waveform for each of the fifteen acquired leads shown on the right side in. This program is preferably configured to perform such averaging when executed. The averaging can be performed by aligning all beats to the peak of the QRS complex (marked with small circles in the recorded data) to form the corresponding average beat waveform for each acquired lead. The resulting fifteen average beat waveforms are shown on the left side of Figures 9a - 9c and are used for subsequent time alignment and calculations. Each of the resulting twelve standard leads that form the target standard 12-lead ECG will also be in the form of a beat waveform. It should be noted that, as described above, this time alignment using the QRS complex peak cannot be used to time-align different leads with each other, but only to align the beat waveforms of common leads for averaging purposes. Figures 9a - 9c There is redundancy in the information of the acquired limb leads I-III, and this redundancy can be used to form time-aligned limb leads I-III based on the following equation:

[0136] Lead III = Lead II - Lead I (11)

[0137] Equation (11) can be regarded as the vector sum I + III = II in

[0138] Lead III can be calculated as Lead II - Lead I, but the time shift between sequentially acquired Lead I and Lead II is unknown. In some embodiments, this subtraction can be performed while iteratively shifting the time alignment between I and II until the best consistency between the calculated Lead III and the acquired Lead III is achieved. The program of the watch can be configured to perform such time alignment. When the best time alignment between Lead I and Lead II is achieved, the difference between the calculated Lead III and the acquired Lead III will be minimized. As an example, the acquired Lead I can be used as a reference, and the acquired Lead II is time-shifted. In this way, time-aligned Lead I and II can be formed. Equation (11) above can be used to calculate time-aligned Lead III. In this embodiment where the average beat waveforms have been created, time alignment and calculations are performed on the average beat waveforms, and the resulting time-aligned leads I-III will be in the form of beat waveforms as shown on the left side of Figure 7 Figure 9a .

[0139] Using the above equations (4) to (6), the processing unit of the watch calculates the time-aligned augmented limb leads aVR, aVL, and aVF based on leads I-III aligned according to the accurate time. The calculated augmented limb leads aVR, aVL, and aVF will also be in the form of pulsation waveforms.

[0140] Contrary to the case of the standard limb leads I-III measured between physical electrodes, when using a conventional ECG machine, the standard precordial leads V1-V6 are usually calculated according to the virtual WCT based on the above equations (7) and (8). However, due to the specific information redundancy obtained by sequentially recording six arm-based chest leads CR1-CR6 and six arm-based chest leads CL1-CL6, precise time alignment can be performed, which ultimately enables the six standard precordial leads V1-V6 to be correctly calculated based on the time-aligned leads with high accuracy.

[0141] In one embodiment and with reference to Figure 8 , using the acquired lead CL1 as the alignment reference, and using the equation CL1 = CR1 - I, time alignment is performed between the time-aligned lead I and the acquired arm-based lead CR1. CL1 can be time-shifted relative to lead I that has already been time-aligned with II and III. By performing similar time alignment using all pairs of CRi and CLi, the six time-aligned leads CR1-CR6 (i = 1-6) can be formed using the following equation:

[0142] CLi = CRi - I (12)

[0143] The time alignment of each CRi of the six acquired arm-based chest leads CR1-CR6 can be performed by: relative to the acquired lead I that has already been time-aligned a iteratively shifting the time alignment of the acquired CRi a (where the subscript a represents the acquired lead), until the difference between the calculated lead CLi c (where the subscript c represents the calculated lead) and the acquired reference value CLi a is minimized, and the calculated lead CLi c is calculated based on the acquired value CRi a and I a as:

[0144] CLi c = CRi a - I a (13).

[0145] After the above time alignment and calculations have been performed by the processing unit, three time-aligned limb leads I, II, and III, and six time-aligned chest leads CR1-CR6 can now be obtained. Since all these leads are aligned with each other in time, they can be used for calculations. Using the above equation (9) (Vi = CRi - (I + II) / 3), the processing unit can now calculate six time-aligned standard precordial leads V1-V6 from the time-aligned lead I, the time-aligned lead II, and the time-aligned leads CR1-CR6.

[0146] It can be noted that the process of creating the standard precordial leads V1-V6 from sequential data is different from the process of time-aligning the standard limb leads I-III. When creating V1-V6, time alignment is performed using twelve sequentially acquired leads that are not part of the set of twelve standard leads. To obtain each precordial lead Vi in V1-V6, the inventive concept uses two measurements of the associated chest electrode Ci and the acquired values of leads that are not part of the standard ECG.

[0147] Figure 12 An example of a standard 12-lead ECG obtained by the inventive method is shown, which is formed by three time-aligned standard limb leads I-III, three time-aligned standard augmented limb leads aVR, aVL, and aVF, and six time-aligned standard precordial leads V1-V6, which are created from Figures 9a - 9c the fifteen initially asynchronous acquired leads. Figure 12 Each of the twelve standard leads in Figure 12 is in the form of an average beat waveform. At the bottom of the ECG in

[0148] In one embodiment, an acquired limb lead II measured over a period of time covering multiple heartbeats is also included. Other embodiments may alternatively or additionally display any combination of the fifteen leads acquired over a period of time covering multiple heartbeats.

[0149] As an example, using step (b), Vi can be calculated by using CR1-CR6 as a reference and the equation

[0150] CRi = CLi + I (12’),

[0151] and time-shift each acquired lead CLi a relative to the time-aligned lead I until the calculated lead CRi c (calculated as the sum of the acquired CLi a + the time-aligned acquired I a ) has a minimum difference from the acquired CRi a (which represents optimal alignment), alternatively time-align the leads CL1-CL6 with the time-aligned lead I to calculate one or more of the six standard precordial leads V1-V6. Thus, any one of the six precordial leads V1-V6 can also be calculated according to the time-aligned lead CLi and the time-aligned leads III and I as:

[0152] Vi = CLi - (III - I) / 3 (14)

[0153] In addition, each of the precordial leads V1-V6 can be calculated as described above according to the time-aligned acquired version of CRi or CLi, or according to the time-aligned calculated version of CRi or CLi. For example, as an alternative to calculating Vi using the time-aligned acquired lead CRi as described in the above example, Vi can alternatively be calculated according to the time-aligned calculated version of CLi using equation (14), where the time-aligned lead CLi is calculated according to the time-aligned lead CRi and the time-aligned lead I obtained in step (a). In the same way, each Vi can also be calculated according to the time-aligned calculated version of CRi, where the time-aligned lead CRi is calculated according to the time-aligned acquired lead CLi and the time-aligned lead I obtained in step (b).

[0154] The order of time alignment and calculation is not required, and the inventive concept is considered to cover all possible orders as long as the calculation is performed on the required time-aligned values.

[0155] As an alternative, it is possible to start with the time alignment of lead I with the chest electrodes referenced to the arms, and then create the time-aligned leads I-III.

[0156] When all time alignments have been performed, the calculation of the six precordial leads V1-V6 can be carried out. As an alternative, each precordial lead Vi can be calculated as soon as the corresponding time-aligned leads required for calculating Vi have been formed.

[0157] In some embodiments, all fifteen acquisitions can be performed before any averaging, time alignment, and calculations are carried out. In other embodiments, one or more of the time averaging action, time alignment action, and calculation action can be performed once the data required for the corresponding action is available.

[0158] Now refer to Figure 10 , which shows how crucial it is to obtain a very precise time alignment in order to subsequently obtain correct calculated values based on the time-aligned values. Figure 10 The pulsation waveforms in Figure 10 were obtained from a study of subjects by the inventors using the inventive concept. Each pulsation waveform within a 1000 millisecond time period is shown. a and the acquired lead CL1 a between the time shift effect. In Figure 10 , the subscript "a" means "acquired", and the subscript "c" means "calculated".

[0159] Figure 10 The first row in a shows the acquired lead I a . The second row shows the acquired lead CL1 c . The third row shows the lead CR1 calculated according to equation (12) a = I a + CL1 a . The 4th row shows the acquired lead CR1 a . When the acquired lead CL1 a in the top two rows is time-aligned with the acquired lead I c , the calculated lead CR1 a should match the acquired lead CR1 a as closely as possible, i.e., the difference CR1 c - CR1 a in the 5th row of c - CR1 a is shown for different time shifts in steps of 1 ms. In other embodiments, the time shift can be an interval shorter or longer than 1 ms to optimize the time alignment. In this example, a 4 ms time shift achieves the best time alignment, which results in the difference in the 5th row being effectively zero. An incorrect time shift of just one millisecond or a few milliseconds (remember the entire waveform is approximately 1000 milliseconds long) will result in a significantly incorrect match, as shown in the waveforms at the far right and far left of the 5th row. Therefore, even the slightest incorrect time shift during time alignment can result in an incorrectly calculated Vi value. Thus, the almost zero value obtained for a 4 ms time shift will result in the most correctly calculated lead V1.

[0160] Now refer to Figure 11a and Figure 11b which shows limb leads I, II, III, aVR, aVL, and aVF from the same subject as in Figures 9a - 9c . This is the result of a study conducted by the inventors that compared the results of the sequential acquisition, subsequent alignment, and calculation from fifteen leads according to the inventive concept on the one hand, with the results of the conventional simultaneous acquisition of all twelve leads on the other hand.

[0161] The first two columns labeled "12 Leads Simultaneous, Acquisition 1" and "12 Leads Simultaneous, Acquisition 2" show two independent simultaneous acquisitions recorded by a synchronous conventional 12-lead ECG machine, which represent the "true" leads. The third column "Asynchronous Acquisition, Correct Alignment" shows the results obtained by the inventive concept based on the sequential acquisitions from the same subject in Figures 9a - 9c by performing time alignment and calculation according to the inventive concept. The fourth column "Asynchronous Acquisition, R-Wave Alignment" shows the "unaligned" results obtained when time alignment is not performed according to the inventive concept but only the maximum deviation of the QRS complex is used as a reference for time-aligning the acquired leads. The most obvious differences are highlighted with circles, such as those for V1, V2, and V3. Figure 11a and Figure 11b also clearly show the excellent match between the "true" leads in the first two columns and the results obtained by the inventive concept.

[0162] The derived vectorcardiography, VCG

[0163]

[0164] Table I

[0165] Table I above is based on Kors' matrix, which shows the coefficients to be multiplied and summed with the values of leads I, II, and V1 - V6 in order to calculate the derived Frank leads X, Y, and Z for VCG. Thus, the Frank leads X, Y, and Z can be mathematically derived (calculated) from the eight standard leads I, II, and V1 - V6 created according to the inventive concept because these leads are all time-aligned. Therefore, the inventive concept also makes it possible to perform VCG analysis on sequentially acquired ECG signals and, as a result, also enables advanced diagnostic algorithms based on VCG leads.

[0166] For example, Frank lead X can be calculated using the matrix above as follows:

[0167] X = 0.38I – 0.07II – 0.13V1 + 0.05V2 – 0.01V3 + 0.14V4 + 0.06V5 + 0.54V6

[0168] Figure 11c and Figure 13 shows the results of generating leads X, Y, and Z from leads I, II, and V1-V6 obtained according to the inventive concept. When QRS time alignment is not used, a slight deviation is particularly noted in lead Z. However, the substantial advantages obtained by the present invention may be better understood in the graphical VCG plot.

[0169] Figure 13 shows Figure 11c a three-dimensional plot of the derived X, Y, and Z leads. The same labels as in Figure 11c are used. The first two represent the results obtained from separate simultaneous acquisitions using a 12-lead ECG. The curves drawn with a thicker solid line represent the results obtained from time alignment and calculation based on sequentially acquired data according to the inventive concept. The fourth curve drawn with a dashed line shows the "unaligned" result when time alignment is performed only using the maximum deviation of the QRS complex and the inventive concept is not used. Figure 13 The VCG analysis in

[0170] clearly demonstrates how the inventive concept (black solid line) shows excellent agreement with the true reference values, while the dashed curve shows a substantial difference.

[0171] As mentioned in the overview section, the redundancy of the information present in the fifteen acquired leads can optionally be used to obtain additional advantages, including noise reduction and / or reduced acquisition time, by averaging the acquired and calculated versions of the leads, thereby making the best use of all available redundant information. The averaging is performed by at least one processing unit. In the descriptions and calculations given below as examples of using this technique, the acquired leads are identified by the subscript "a", the calculated leads are identified by the subscript "c", and the resulting averaged leads are identified by an underline. The general equation can be written as follows: Lead X =(Lead X a + Lead X c ) / 2, while it should be understood that other types of averaging can also be considered.

[0172] For lead III, such additional averaging can be performed as follows: If III a is used as the reference for forming time-aligned I a and time-aligned II a to time-align I a and II a , then the calculated time-aligned lead IIIc Subsequently, it can be calculated as:

[0173] Time-aligned III c = Time-aligned II a - Time-aligned I a

[0174] Two versions of Lead III that are currently available: one is the acquired Version III a , and one is the calculated Version III c , both of which are time-aligned. Since these two versions are time-aligned with each other, they can be averaged as:

[0175] III = (III a + III c ) / 2

[0176] The acquired average lead III is obtained by using information redundancy and can exhibit a lower noise level.

[0177] The average lead can be calculated in the same way I , first time-aligning II a and III a using I a as a reference, then calculating the time-aligned I a and III a based on the time-aligned II c , and finally calculating the average I = (I a + I c ) / 2.

[0178] The average lead II can be calculated in the same way.

[0179] The average augmented limb leads can be calculated by averaging the augmented leads generated from any two combinations of the acquired leads I and II, II and III, or I and III aVR , aVL and aVF . Alternatively, when using the above-averaged leads I , II and III , the leads aVR , aVL and aVF will be the result of calculating these leads.

[0180] Each average precordial lead Vi can be based on the average CRi , I andII Calculated as Vi = CRi -( I + II ) / 3. Alternatively, Equation (14) and CLi can be used. In this example, the average CRi can be calculated as the average of the acquired version and the calculated version of CRi:

[0181] CRi = (CRi a + CRi c ) / 2

[0182] The calculated version of CRi c can be calculated using Equation (10) as:

[0183] CRi c = Ci - RA

[0184] Thereafter, each average Vi can be calculated using Equation (9) as:

[0185] Vi = CRi -( I + II ) / 3

[0186] By using this averaging technique and all the information redundancy in the acquired signals, the acquisition time can be shortened while keeping the noise at the same level. For example, a standard 12-lead ECG can be generated based on each successive acquisition that is approximately only 5 seconds long. Obviously, when the ECG acquisition has to be recorded successively, the shortened acquisition time is particularly beneficial.

[0187] Example I

[0188] Figure 14 shows a flowchart of an embodiment according to the concepts of the present invention, which includes a series of actions for generating a standard 12-lead ECG. In this embodiment, all the time alignment and calculations for generating the standard twelve ECG leads based on fifteen successive acquired ECG leads can be performed in a smartwatch (such as Figures 4 to 6 the smartwatch 10 in). However, optionally, the smartwatch can be connected to a smartphone, a tablet computer, a computer, etc., for providing an enhanced user experience and functions. The smartwatch 10 has a user interface, at least one processing unit, and a non-transitory computer-readable recording medium having a program called "watch app" thereon, and the program is configured to execute the steps shown in the flowchart.

[0189] In a first step, the user opens the watch app. At this point in time, as a non-limiting example, the user can wear the smartwatch on one wrist, as Figure 4 shown. On the user interface (or on a connected smartphone, etc.), the user initiates the process by selecting "Record 12-Lead ECG". The watch provides visual and / or audible indications for positioning the watch and the hand for the next acquisition. If a smartphone, etc. communicates with the smartwatch, it can also provide instructions, such as graphical instructions for positioning the smartwatch. For example, the first instruction can be to hold the watch as Figure 4 shown to obtain Lead I. Thereafter, the user instructs the watch "Next" to start the first acquisition. As a non-limiting example, this can be performed by pressing a button on the display, pressing a physical button, giving a voice command, or other means. Now, the watch performs the acquisition of the first lead for a predetermined period of time. During the acquisition, the ECG signal quality can optionally be presented on the watch's display. This can be beneficial for the person who can help the person record the ECG, or for a second person (doctor, nurse, caregiver, other healthcare professional, other assistant, etc.) who does this completely for the person. At the end of each acquisition, the acquired ECG signal is saved in the watch's memory. As Figure 14 shown, the above sequence is repeated for all leads. At the end of the final 15th acquisition, the watch app performs the above alignment and calculation to generate a 12-lead ECG. As described above, the acquired raw data can optionally be saved for various purposes.

[0190] The generated 12-lead ECG can be displayed on the smartwatch, on a larger display of an external synchronized electronic device (such as a smartphone, tablet, or computer), and shared, for example, via email.

[0191] Example II

[0192] Figure 15 shows a flowchart of another embodiment according to the inventive concept, which includes a series of actions for generating a 12-lead standard ECG using a system 100 according to an embodiment of the inventive concept, and the system 100 is schematically shown in Figure 16 In this embodiment, these actions are performed partly by a wearable or portable electronic device (here in the form of a smartwatch 10) and partly by one or more external devices. In the system example shown in Figure 16 the system 100 also includes a connected smartphone 20, a cloud server 30, etc. and a dedicated server 40 that communicate with each other, as Figure 16As shown. It may also include a separate computer 50 that communicates with the smartwatch 10, the smartphone 20, the cloud server 30, and the dedicated server 40. The connection between the smartwatch and the smartphone 20 can generally be via Bluetooth, while the connections to and from the servers 40 and 50 can be via the Internet. In this example, the "at least one processing unit" included in the system 100 may include one or more processing units in the watch 10, the smartphone 20, the cloud server 30, and / or the dedicated server 40. As described above, the actions of time alignment and calculation can be performed substantially anywhere.

[0193] In addition to the user initiating the acquisition by opening a dedicated app or web page on, for example, the smartphone 20, the acquisition sequence is similar to Figure 14 Example I in. After selecting "Record 12-Lead ECG" on the dedicated app or web page, the user receives an indication of where to place the smartwatch 10 for the first of the fifteen acquisitions. A 30-second (or some other predetermined time period) acquisition of the ECG signal representing Lead I is performed. As in the previous example and as indicated by reference numeral 21, the quality of the ECG signal can optionally be observed "in real time" during the acquisition on the smartphone 20 to give visual feedback on the signal quality. This visual feedback can also be provided on the display of the smartphone 10 as indicated by reference numeral 11, or not provided at all. After the acquisition of the lead is completed, the user is instructed to give an input, for example, by pressing the "Next" button on the web page or app 20 again, to indicate the completion of the acquisition of the first lead. The registration time point is registered, and the registered time is associated with the most recent acquisition before the registration time. Thus, each acquisition will be associated with a "tag" such that the system will know which acquisition corresponds to which of the fifteen sequentially acquired leads. The web page or app records the time when the "Next" button is pressed, and the ECG acquisition is subsequently recognized as the ECG acquired immediately before the time when the "Next" button was pressed.

[0194] At the end of all acquisitions or each acquisition, the smartwatch 10 saves the ECG signal to the smartphone app, and the smartphone app transfers the ECG acquisition to the cloud server 30 via the Internet connection of the smartphone 20.

[0195] At the end of the final 15th acquisition, the dedicated network server 40 (which can alternatively be a smartphone-based app) contacts the cloud server 30 and downloads the fifteen ECG acquisitions to the dedicated server 40, where the alignment and calculation according to the concepts of the present invention are performed. Thereafter, a 12-lead ECG similar to the ECG shown in Figure 12 is presented to the user. As Figure 16As shown, the generated 12 - lead ECG can be sent to the smartphone 20 and / or the computer 50, where in the smartphone 20 and / or the computer 50, the 12 - lead ECG can be displayed on a larger display as indicated by reference numeral 51. The user can view the ECG or email the ECG as, for example, a pdf file to themselves or their healthcare professional.

[0196] In this example, if the user initially does not have access to a smartphone, the smartwatch can still be used to perform the recording. The acquired leads will be automatically transferred to the smartphone the next time the smartwatch and the smartphone are connected, then transferred to the cloud, and ultimately used to calculate and display a standard 12 - lead ECG.

[0197] The following are examples of embodiments of the systems and methods described herein.

[0198] Methods and systems for determining or generating one (or more) ECGs using a two - electrode (e.g., single - lead) device are disclosed herein. The method can include obtaining a series of asynchronously (e.g., non - time - aligned) measured leads. Each asynchronously measured lead can be acquired via two electrodes (e.g., a single lead) of the device. The two electrodes (e.g., a single lead) can be positioned at different locations on the patient's body during the acquisition of the series of asynchronously measured leads.

[0199] The method can include determining a corresponding time - shift for one or more of the asynchronously measured leads. For example, a first lead (e.g., limb lead I) can be determined by measuring a first potential (e.g., voltage, voltage function, etc.) between two physical electrodes of the device. A second lead (e.g., limb lead II) can be determined by measuring a second potential between two physical electrodes of the device. A third lead (e.g., limb lead III) can be determined by measuring a third potential between two physical electrodes of the device. The first lead, the second lead, and the third lead can correspond to the asynchronously measured leads (e.g., they can be obtained or measured sequentially in time). The first lead, the second lead, and the third lead can correspond to the average waveforms of the asynchronously measured leads.

[0200] The method may include performing a time shift on one or more of the first lead or the second lead. For example, a time shift may be performed on one or more of the first lead or the second lead to determine a time shift value that minimizes the difference between (a) a third lead (e.g., limb lead III) and (b) a difference that is the difference between (i) the second lead (e.g., limb lead II) and (ii) the first lead (e.g., limb lead I). Once the time shift value that minimizes the difference between (a) the third lead (e.g., limb lead III) and (b) a difference that is the difference between (i) the second lead (e.g., limb lead II) and (ii) the first lead (e.g., limb lead I) is determined, the method may include determining a time-aligned version of the first lead, a time-aligned version of the second lead, and a time-aligned version of the third lead.

[0201] The time-aligned versions of the first lead and the second lead may be determined by applying the determined time shift value to one or more of the first lead or the second lead. For example, the first lead may be used as a reference, and the time shift value may be applied to the second lead. In another example, the second lead may be used as a reference, and the time shift value may be applied to the first lead. In another example, a portion of the time shift value may be applied to each of the first lead and the second lead to determine the time-aligned versions of the first lead and the second lead. The time-aligned version of the third lead may be determined by taking the difference between the time-aligned version of the second lead and the time-aligned version of the first lead. In an example, the first lead, the second lead, and the third lead may correspond to limb leads (e.g., limb leads I-III) acquired asynchronously. In an example, each of the first lead, the second lead, and the third lead may correspond to an average beat waveform determined based on asynchronous measurements of the device.

[0202] The method may further include using one or more of the time-aligned version of the first lead, the time-aligned version of the second lead, and / or the time-aligned version of the third lead to determine one or more virtual or augmented leads. For example, three augmented leads may be determined based on the time-aligned version of the first lead, the time-aligned version of the second lead, and the time-aligned version of the third lead. The three augmented leads may correspond to augmented limb leads aVR, aVL, and aVF. For example, in the above equations (4)-(6), the time-aligned version of the first lead, the time-aligned version of the second lead, and / or the time-aligned version of the third lead may be used as limb leads I-III, respectively, to determine three augmented leads corresponding to the augmented limb leads aVR, aVL, and aVF.

[0203] In an example, there can be 15 asynchronous leads determined or measured using the device. For example, the 15 asynchronous leads can include three asynchronous limb leads (e.g., limb leads I - III), six first asynchronous arm - based chest leads (e.g., CR1 - CR6), and six second asynchronous arm - based chest leads (CL1 - CL6). In an example, a corresponding average beat waveform can be determined for one or more or each of the 15 asynchronous leads. The averaging can be performed by aligning the peaks within the corresponding asynchronous lead.

[0204] In an example, a time alignment can be performed between one or more of the six first asynchronous arm - based chest leads (e.g., CR1 - CR6) and one or more of the six second asynchronous arm - based chest leads (CL1 - CL6) using time - aligned versions of the three limb leads (e.g., the time - aligned version of the first lead, the time - aligned version of the second lead, and / or the time - aligned version of the third lead). For example, a time alignment can be performed between the first of the six first asynchronous arm - based chest leads (e.g., CR1), the first of the six second asynchronous arm - based chest leads (e.g., CL1), and the time - aligned version of the first lead.

[0205] For example, the first of the six second asynchronous arm - based chest leads (e.g., CL1) can be used as an alignment reference to determine the time shift to be applied to the first of the six first asynchronous arm - based chest leads (e.g., CR1) based on the time - aligned version of the first lead (e.g., time - aligned limb lead I). In another example, the first of the six first asynchronous arm - based chest leads (e.g., CR1) can be used as an alignment reference to determine the time shift to be applied to the first of the six second asynchronous arm - based chest leads (e.g., CL1) based on the time - aligned version of the first lead.

[0206] As an example, the time-aligned version of the first of the six first arm-based precordial leads (e.g., CR1) can be determined by determining the time-shift value that minimizes the difference between (a) the measured version of the first of the six second arm-based precordial leads (e.g., CL1) and (b) a difference that is the difference between (i) the first of the six first arm-based precordial leads (e.g., CR1) and (ii) the time-aligned version of the first lead (e.g., the time-aligned limb lead I). The determined time-shift that minimizes this difference can then be applied to the first of the six first arm-based precordial leads (e.g., CR1) in order to determine the time-aligned version of the first of the six first arm-based precordial leads (e.g., the time-aligned lead CR1). The process can then be repeated for the second of the six first arm-based precordial leads (e.g., CR2). In other words, the time-aligned version of the second of the six first arm-based precordial leads (e.g., CR2) can be determined by determining the time-shift value that minimizes the difference between (a) the measured version of the second of the six second arm-based precordial leads (e.g., CL2) and (b) a difference that is the difference between (i) the second of the six first arm-based precordial leads (e.g., CR2) and (ii) the time-aligned version of the first lead (e.g., the time-aligned limb lead I). Applying the determined time-shift to the second of the six first arm-based precordial leads (e.g., CR2) can be used to determine the time-aligned version of the second of the six first arm-based precordial leads (e.g., the time-aligned lead CR2). Similar time-shift determinations can be used to determine the time-aligned versions of the third, fourth, fifth, and sixth of the six first arm-based precordial leads (e.g., the time-aligned leads CR3, CR4, CR5, and CR6, respectively).

[0207] The time-aligned first lead (e.g., the time-aligned limb lead I), the time-aligned second lead (e.g., the time-aligned limb lead II), and the six time-aligned first arm-based precordial leads (e.g., the time-aligned leads CR1-CR6) can then be used to determine the six standard precordial leads (e.g., precordial leads V1-V6). For example, the time-aligned first lead (e.g., the time-aligned limb lead I), the time-aligned second lead (e.g., the time-aligned limb lead II), and the six time-aligned first arm-based precordial leads (e.g., the time-aligned leads CR1-CR6) can be used in equation (9) above in order to determine the six standard precordial leads (e.g., precordial leads V1-V6).

[0208] Then, a standard 12-lead ECG can be obtained or formed by the first lead aligned in time (e.g., the limb lead I aligned in time), the second lead aligned in time (e.g., the limb lead II aligned in time), the third lead aligned in time (e.g., the limb lead III aligned in time), three determined augmented leads (e.g., aVR, aVL, and aVF), and six determined standard precordial leads (e.g., precordial leads V1-V6).

[0209] It should be noted that the determination or calculation can be performed by a processor and a memory co-located with the device containing the electrodes (e.g., within a wearable device such as a smartwatch), or by a processor operatively communicating with the device containing the electrodes (e.g., a smartphone communicating with the smartwatch, a server system communicating directly or indirectly with the smartwatch, etc.). The processing steps can be performed by a single processor or divided among multiple processors. Additionally, the acquisition of the leads can be performed in any order. Although specific leads are used as the time reference in the examples described herein, which specific lead is used as the time reference and which lead is applied with a time shift can vary based on design choices.

Claims

1. A computer-implemented method for generating a standard 12-lead ECG, the standard 12-lead ECG being formed by three standard limb leads I, II, III, three standard augmented limb leads aVR, aVL, aVF, and six standard precordial leads V1 to V6 from fifteen asynchronous, sequentially acquired leads, the fifteen asynchronous, sequentially acquired leads including three acquired limb leads I, II, and III, and twelve acquired arm-based chest leads CR1-CR6 and CL1-CL6, the three acquired limb leads I, II, and III being referred to as acquired leads I-III, and the twelve acquired arm-based chest leads CR1-CR6 and CL1-CL6 being referred to as acquired leads CR1-CR6 and CL1-CL6; Among them, For an integer i equal to 1 to 6, each pair of acquired leads CRi and CLi among the acquired leads CR1-CR6 and CL1-CL6 represents the acquired voltage difference between the right arm and the left arm and the common chest position Ci associated with the corresponding standard precordial lead Vi, The method includes: Based on the acquired leads I-III, create time-aligned limb leads I, II, and III by using the equation: Lead II - Lead I = Lead III, the time-aligned limb leads I, II, and III being referred to as time-aligned leads I-III; Calculate three time-aligned augmented limb leads aVR, aVL, and aVF based on the time-aligned leads I-III; For an integer i equal to 1 to 6, perform one of (a) and (b): (a) Create a time-aligned arm-based chest lead CRi by time-aligning the acquired lead CRi with the acquired lead I such that the calculated difference CRi - I representing the calculated arm-based chest lead CLi has the best consistency with the acquired lead CLi, the time-aligned arm-based chest lead CRi being referred to as the time-aligned lead CRi, and the calculated arm-based chest lead CLi being referred to as the calculated lead CLi, (b) Create a time-aligned acquired arm-based chest lead CLi by time-aligning the acquired lead CLi with the acquired lead I such that the calculated sum CLi + I representing the calculated arm-based chest lead CRi has the best consistency with the acquired lead CRi, the time-aligned acquired arm-based chest lead CLi being referred to as the time-aligned lead CLi, and the calculated arm-based chest lead CRi being referred to as the calculated lead CRi; And For an integer i equal to 1 to 6, calculate a time-aligned precordial lead Vi based on one of the time-aligned leads I, the time-aligned lead II, and the time-aligned lead III, and one of the time-aligned leads CRi and the time-aligned lead CLi for forming time-aligned precordial leads V1-V6; Among them, the time-aligned limb leads I-III, the time-aligned augmented limb leads aVR, aVL, and aVF, and the time-aligned precordial leads V1-V6 together form a standard 12-lead ECG.

2. The method according to claim 1, further comprising averaging each of the fifteen asynchronously and sequentially acquired leads to create fifteen corresponding average beat waveforms, and using the average beat waveforms as the acquired leads in the step of creating the time-aligned limb leads I-III, and in steps (a) and (b) of creating the time-aligned leads CR1-CR6 and the time-aligned leads CL1-CL6.

3. The method according to any one of the preceding claims, wherein: The time alignment in step (a) is performed by iteratively moving the acquired lead CRi and the acquired lead I relative to each other to achieve the best consistency between the difference CRi-I and the acquired lead CLi; And The time alignment in step (b) is performed by iteratively moving the acquired lead CLi and the acquired lead I relative to each other to achieve the best consistency between the sum CLi+I and the acquired lead CRi.

4. The method according to any one of the preceding claims, wherein, The time-aligned lead I is created before performing step (a) or step (b) respectively, and the time-aligned lead I is used to perform the time alignment in step (a) or (b) respectively.

5. The method according to any one of the preceding claims, wherein, The action of creating the time-aligned limb leads I-III includes: creating the first and second time-aligned leads in the time-aligned limb leads I-III by time-shifting the associated first and second acquired leads in the acquired limb leads I-III using the third acquired lead in the acquired limb leads I-III as a reference; and calculating the remaining third time-aligned lead in the time-aligned limb leads I-III based on the first and second time-aligned leads.

6. The method according to any one of the preceding claims, wherein, The fifteen asynchronously and sequentially acquired leads are acquired using only two electrodes.

7. The method according to claim 6, wherein, For an integer i equal to 1 to 6, the acquired leads CRi and the acquired leads CLi are measured one after another in any order while keeping one of the two electrodes positioned at the common chest position Ci.

8. The method according to any one of the preceding claims, further comprising averaging each time-aligned lead with an associated calculated version of the same lead for creating an associated averaged time-aligned lead.

9. The method according to any one of the preceding claims, wherein, The method is performed using a wearable or portable electronic device with a single lead including two electrodes; and wherein the fifteen asynchronously and sequentially acquired leads are acquired by sequentially changing the positions of the two electrodes on the body of the subject.

10. A system for generating a standard 12-lead ECG formed by three standard limb leads I, II, III, three standard augmented limb leads aVR, aVL, aVF, and six standard precordial leads V1 to V6, the system comprising: Two electrodes; At least one processing unit configured to perform the following actions: When the two electrodes are successively moved to different positions on a subject's body, fifteen ECG leads between the two electrodes are successively acquired. The fifteen ECG leads include three acquired limb leads I, II, and III and twelve acquired arm-based chest leads CR1 - CR6 and CL1 - CL6. The three acquired limb leads I, II, and III are referred to as the acquired leads I - III, and the twelve acquired arm-based chest leads CR1 - CR6 and CL1 - CL6 are referred to as the acquired leads CR1 - CR6 and CL1 - CL6. Wherein, for an integer i equal to 1 to 6, each pair of the acquired leads CR1 - CR6 and CL1 - CL6, the acquired leads CRi and CLi, represents the acquired voltage difference between the right arm and the left arm respectively and the common chest position Ci associated with the corresponding standard precordial lead Vi; Based on the acquired leads I - III, three time-aligned limb leads I, II, and III are created by using the equation: Lead II - Lead I = Lead III. The time-aligned limb leads I, II, and III are referred to as the time-aligned leads I - III; Based on the time-aligned leads I - III, three time-aligned augmented limb leads aVR, aVL, and aVF are calculated; For an integer i equal to 1 to 6, (a) A time-aligned arm-based chest lead CRi is created by time-aligning the acquired lead CRi with the acquired lead I, such that the calculated difference CRi - I representing the calculated arm-based chest lead CLi has the best consistency with the acquired lead CLi. The time-aligned arm-based chest lead CRi is referred to as the time-aligned lead CRi, or (b) A time-aligned acquired arm-based chest lead CLi is created by time-aligning the acquired lead CLi with the acquired lead I, such that the calculated sum CLi + I representing the calculated arm-based chest lead CRi has the best consistency with the acquired lead CRi. The time-aligned acquired arm-based chest lead CLi is referred to as the time-aligned lead CLi; And For an integer i equal to 1 to 6, based on one of the time-aligned lead I, the time-aligned lead II, and the time-aligned lead III, and one of the time-aligned lead CRi and the time-aligned lead CLi, a time-aligned precordial lead Vi is calculated to form time-aligned precordial leads V1 - V6; Wherein, the time-aligned leads I - III, the time-aligned augmented limb leads aVR, aVL, and aVF, and the time-aligned precordial leads V1 - V6 together form a standard 12-lead ECG.

11. The system according to claim 10, wherein, The system is incorporated into a portable or wearable electronic device. The electronic device includes the two electrodes and includes at least one processing unit configured to perform the actions.

12. The system according to claim 11, wherein, The electronic device includes a smartwatch, a smartphone, or a dedicated ECG device.

13. The system according to claim 10, wherein, The system is partially incorporated into a portable or wearable electronic device including the two electrodes and is partially incorporated into at least one external device, and the electronic device and the at least one external device are configured to communicate with each other.

14. The system according to claim 13, wherein, The at least one external device includes at least one server.

15. The system according to any one of claims 10 to 14, wherein The at least one processing unit is configured to execute the method according to any one of claims 1 to 9.

16. A non-transitory computer-readable recording medium having recorded thereon a program including a program code portion which, when executed on one or more processing units, is configured to execute the computer-implemented method according to any one of claims 1-9.

17. The non-transitory computer-readable recording medium according to claim 16, wherein, When executed on the electronic device, the program code portion is further configured to control the acquisition of the fifteen asynchronous and sequentially acquired leads.

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