A non-invasive method and system for measuring characteristics of myocardial tissue motion

Abstract

A non-invasive method for measuring the motion characteristics of myocardial tissue includes: transmitting a plurality of generated synchronous quadrature, different frequency, phase controllable adjustable periodic alternating current to a living body (20) to generate a plurality of different frequency periodic alternating voltage signals; receiving the alternating voltage signals modulated by the changes of the cardiac tissue (25) in the living body (20) to obtain the frequency response of the living body (20); calculating the resistance and capacitance of the cardiac tissue (25) according to the frequency response; and estimating the motion characteristics of the myocardial tissue according to the resistance and capacitance. By introducing the longitudinal average length of myocardial cells and calculating the longitudinal average length change of the myocardial cells according to the capacitance, a description method of the longitudinal elasticity of the whole heart is given. A continuous, high sampling rate, non-invasive method is provided to measure the motion of the myocardial tissue at the whole cell level, so that more subtle abnormal changes of the myocardial cells can be detected.

Description

Technical Field

[0001] This invention relates to a measurement technique for biological tissues, and more particularly to a non-invasive method and system for measuring the motility characteristics of myocardial tissue. Background Technology

[0002] The heart's fundamental function is to pump blood, circulating it throughout the body to provide oxygen and nutrients to tissues. Therefore, measuring cardiac dynamic parameters is of paramount importance in the medical field. The structural characteristics of cardiomyocytes indicate that they are elastic tissues. Thus, the motion of myocardial tissue, especially its elasticity, should be a primary measurement target. Currently, the stress-strain relationship of myocardial tissue has been extensively studied, and related applications are mainly achieved through ultrasound imaging systems.

[0003] The heart has four chambers, comprising two atria and two ventricles. Under normal circumstances, the right atrium collects blood from the superior and inferior vena cava. The blood then enters the right ventricle and is pumped from there into the lungs. The left atrium receives blood from the pulmonary veins and sends it to the left ventricle, which pumps the blood throughout the body via the aorta. The heart wall has a three-layered structure: the endocardium, the myocardium, and the epicardium. The endocardium is a single layer of squamous epithelium lining the heart chambers and valves. The myocardium is the muscle of the heart, a layer of involuntary striated muscle tissue constrained by a collagen framework that allows the cardiomyocytes to arrange themselves on curved sheets, forming a spiral structure overall. The myocardium is the focus of this invention. The pericardium is a double-layered sac containing the heart and the roots of the great vessels.

[0004] Under pathological conditions, the two main concerns are hypertension and myocardial ischemia. Long-term hypertension can eventually lead to ventricular hypertrophy and even heart failure. Ischemia, primarily caused by coronary artery stenosis, can ultimately trigger a heart attack, followed by myocardial infarction and then heart failure. This invention focuses on the early detection of changes in myocardial tissue, which can be used to prevent sudden cardiac arrest.

[0005] Numerous methods exist for measuring cardiac function at different levels, such as organ, tissue, and cellular. At the organ level, ventricular volume estimation can be achieved through image construction. Stroke volume (SV) and ejection fraction (EF) can also be measured, representing the overall pumping function of the heart. However, these parameters do not describe the mechanical properties of the tissue. Direct measurement of strain on the ventricular wall has proven to be a crucial measure of myocardial tissue activity, indirectly reflecting cardiac function. This measurement is currently primarily performed using paired-spot Doppler ultrasound or ultrasound speckle technology. Torsion of the systolic LV from ultrasound speckle tracking imaging is another technique for assessing cardiac function. Simultaneously, omnidirectional longitudinal strain has also proven to be a useful tool for predicting cardiotoxicity during chemotherapy.

[0006] On the one hand, there is currently no non-invasive method to measure the health status of myocardial tissue at the cellular level. On the other hand, even though current technologies can diagnose some health conditions of myocardial tissue, they have some drawbacks. For example, MRI imaging is a very expensive technique. While ultrasound imaging is a relatively inexpensive technique, it is still affected by many factors. First, ultrasound imaging cannot be performed continuously or for extended periods. Second, the resolution of ultrasound imaging results is not high, the results are patient-dependent, and the lack of standardized procedures can lead to variations in the imaging outcomes, resulting in a relatively high cost for ultrasound imaging.

[0007] Numerous prior studies have been conducted on the characterization of invasive myocardial tissue in animals and humans. These studies have shown that local ischemia leads to changes in myocardial impedance, demonstrating impedance variations in cardiac tissue during the cardiac cycle. All these results support the present invention.

[0008] In many cellular parameter measurements, standardization using cell size is required. In equipotential cells, this is achieved by calculating the cell surface area using capacitance measurements. This is a widely used technique. The theoretical basis of this technique is that membrane capacitance is proportional to cell surface area. The membrane capacitance in this theory differs from the capacitance in this invention. The former is capacitance across the membrane, while the capacitance in this invention is capacitance from the membrane to infinity or the ground. Their physical and mathematical basis is that the capacitance in this invention has been shown to be proportional to the average longitudinal length of the cell. This invention is the application of this principle in a system for measuring the kinematic characteristics of myocardial tissue. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention proposes a non-invasive method for measuring the motion characteristics of myocardial tissue. The aim is to calculate the average longitudinal length of myocardial cells by measuring the overall capacitance of the heart tissue, thereby obtaining the motion characteristics of the myocardial tissue. This method is primarily used for non-therapeutic information detection.

[0010] To achieve the above objectives, the present invention provides a non-invasive method for measuring the motion characteristics of myocardial tissue. The method includes: transmitting multiple synchronously orthogonal alternating currents of different frequencies with controllable and adjustable phases into a biological body to generate multiple synchronously periodic alternating voltage signals of different frequencies; receiving the periodic alternating voltage signals modulated by changes in the heart tissue within the biological body to obtain the frequency response of the biological body; calculating the resistance and capacitance of the heart tissue based on the frequency response; and estimating the motion characteristics of the myocardial tissue based on the resistance and capacitance.

[0011] Preferably, calculating the resistance and capacitance of the heart tissue based on the frequency response includes obtaining the system transfer function of the organism based on the frequency response and performing multi-compartment modeling to separate the heart tissue from the peripheral tissue.

[0012] Preferably, estimating the myocardial tissue motion characteristics based on the resistance and capacitance includes: calculating the longitudinal average length and its variation of myocardial cells based on the capacitance, and / or calculating the cardiac pumping blood flow based on the resistance; and obtaining the longitudinal elastic state of the heart as a whole based on the longitudinal average length and its variation of myocardial cells and / or the cardiac pumping blood flow.

[0013] Preferably, the method further includes estimating the health and working status of the heart and myocardium based on the longitudinal elasticity of the heart as a whole.

[0014] Preferably, the estimation includes analyzing the health and working state of the heart and myocardium based on the slope value of the change in the longitudinal elastic state of the whole heart, the delay of the R wave, the peak-to-peak value, the shape of the curve of the change in the longitudinal average length of myocardial cells and its derivative, the health and working state of the heart and myocardium including the contraction speed, time, intensity and pattern of the heart tissue, and / or the diastolic speed, time, recovery and pattern of the heart tissue.

[0015] Preferably, obtaining the organism's frequency response includes calculating a frequency response estimate for a specific frequency every 0.25 to 5 milliseconds.

[0016] Preferably, calculating the longitudinal average length of cardiomyocytes and its changes based on the capacitance includes: detecting the longitudinal average length of cardiomyocytes and its changes over time at a rate of 200 to 4000 times per second; and processing the time series of the longitudinal average length of cardiomyocytes changing over time using digital signal processing methods, including digital filtering, fast Fourier transform (FFT), and time-domain and frequency-domain analysis.

[0017] Preferably, the method further includes referencing an electrocardiogram having the same time series to analyze the longitudinal mean length change sequence of the cardiomyocytes, the reference including comparing the cardiac cycle, systole, and diastole of the electrocardiogram with the longitudinal mean length change sequence of the cardiomyocytes, and / or the boundaries of the cardiac cycle, the systole, and diastole.

[0018] Preferably, the multi-chamber modeling to separate the cardiac tissue from the peripheral tissue includes modeling each chamber by parallel resistors and capacitors, with multiple chambers connected in series or parallel.

[0019] To achieve the above objectives, the present invention also provides a system for implementing the above method, the system comprising a terminal and at least one processor, wherein the terminal comprises: a generator for transmitting multiple synchronously orthogonal periodic alternating currents of different frequencies and with controllable and adjustable phases; one or more sensors for transmitting the periodic alternating currents into a biological body to generate multiple periodic alternating voltage signals of different frequencies, and receiving the periodic alternating voltage signals modulated by changes in cardiac tissue within the biological body to obtain the frequency response of the biological body; the processor is configured to calculate the resistance and capacitance of the cardiac tissue based on the frequency response, and to estimate the kinematic characteristics of the myocardial tissue based on the resistance and capacitance.

[0020] Preferably, the sensor is used to collect single or multiple data from different locations.

[0021] Preferably, the system may include a database for storing the processing results and data of the processor, and the processor may retrieve data from the database.

[0022] Preferably, the processor can be remote, allowing remote observation of the system operating in real-time mode.

[0023] Preferably, the terminal further includes a human-machine interface for controlling the system and / or displaying results.

[0024] Compared with existing technologies, this invention relates to a new technique for detecting myocardial tissue contraction and relaxation at the cellular level. Its advantages are: this invention provides a continuous, high-sampling-rate, non-invasive method to measure the movement of myocardial tissue at the entire cellular level, thereby enabling the detection of even smaller abnormal changes in myocardial cells; this invention avoids traditional techniques that use imaging results for analysis, and has a faster and more standardized measurement method, as well as lower cost. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a two-dimensional abstract model of simulated cardiomyocytes provided in one embodiment of the present invention;

[0027] Figure 2 This is a partial system framework diagram provided in another embodiment of the present invention;

[0028] Figure 3This is a schematic diagram of the arrangement of the transmitting and receiving electrodes provided in another embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the system circuit structure provided in another embodiment of the present invention;

[0030] Figures 5a-5d This is a flowchart of a method provided in another embodiment of the present invention;

[0031] Figures 6a-6d This is a schematic diagram of the electrocardiogram, cardiac resistance and capacitance curves over time for a young male, and the derivative of the capacitance curve, provided by another embodiment of the present invention.

[0032] Figures 7a-7d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance of a normal middle-aged male over time, and a schematic diagram of the derivative of the capacitance curve.

[0033] Figures 8a-8d This is a schematic diagram of the electrocardiogram, cardiac resistance and capacitance curves over time of an elderly woman, and the derivative of the capacitance curve, provided by another embodiment of the present invention.

[0034] Figures 9a-9d This is a schematic diagram of the electrocardiogram, cardiac resistance and capacitance curves over time of an elderly woman, and the derivative of the capacitance curve, provided by another embodiment of the present invention.

[0035] Figures 10a-10d This is a schematic diagram of the electrocardiogram, cardiac resistance and capacitance curves over time of an elderly woman, and the derivative of the capacitance curve, provided by another embodiment of the present invention.

[0036] Figures 11a-11d This is a schematic diagram of the electrocardiogram, cardiac resistance and capacitance curves over time of an elderly woman, and the derivative of the capacitance curve, provided by another embodiment of the present invention.

[0037] Figures 12a-12d This is a schematic diagram of the electrocardiogram, cardiac resistance and capacitance curves over time of an elderly woman, and the derivative of the capacitance curve, provided by another embodiment of the present invention.

[0038] Figures 13a-13d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance of a normal person changing over time, as well as a schematic diagram of the mean cell deformation rate of the heart (similar to the rate of change of tensor).

[0039] Figures 14a-14dThis is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance of a normal person changing over time, as well as a schematic diagram of the mean cell deformation rate of the heart (similar to the rate of change of tensor).

[0040] Figures 15a-15d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance of a normal person changing over time, as well as a schematic diagram of the mean cell deformation rate of the heart (similar to the rate of change of tensor).

[0041] Figures 16a-16d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance of a normal person changing over time, as well as a schematic diagram of the mean cell deformation rate of the heart (similar to the rate of change of tensor).

[0042] Figures 17a-17d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance over time of a person with cardiac tissue abnormalities, as well as a schematic diagram of the mean cardiac cell deformation rate (similar to the rate of change of tensor).

[0043] Figures 18a-18d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance over time of a person with cardiac tissue abnormalities, as well as a schematic diagram of the mean cardiac cell deformation rate (similar to the rate of change of tensor).

[0044] Figures 19a-19d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance over time of a person with cardiac tissue abnormalities, as well as a schematic diagram of the mean cardiac cell deformation rate (similar to the rate of change of tensor).

[0045] Figures 20a-20d This is another embodiment of the present invention, showing the electrocardiogram, cardiac resistance and capacitance curves over time of a person with cardiac tissue abnormalities, as well as a schematic diagram of the mean cardiac cell deformation rate (similar to tensor rate of change). Detailed Implementation

[0046] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0047] This invention relates to non-invasive techniques for detecting the electrical properties of tissues within a living organism, such as the resistance and capacitance of tissues and their changing patterns. Its aim is to capture changes in body fluids, blood flow, and cardiovascular circulatory tissues for monitoring the health status of organisms, verifying the elasticity of the cardiovascular system, and for information detection for non-therapeutic purposes.

[0048] In the embodiments provided by this invention, heart cells are considered to be equipotential. Therefore, cell size can be estimated by capacitance measurement. When heart cells are in their normal position, they can be considered to be arranged in both series and parallel patterns, as the structural cells of the heart spatially constrain the muscle cells. Assuming that heart cells in normal individuals have similar volumes, a variable representing the average geometric scale of the cells can be introduced to represent the changes in cardiomyocytes under the influence of an applied electromagnetic field. A variable particularly relevant to this invention is the average longitudinal length r(t) of the cardiomyocytes. It has been shown to be proportional to the myocardial capacitance measured under an external field. Accordingly, by measuring capacitance, the average longitudinal length of the cardiomyocytes and its changes can be calculated, providing a description of the longitudinal elasticity of the entire heart from the changes in the average longitudinal length of the cardiomyocytes. The overall longitudinal elasticity of the heart can be described as the relative rate of change of myocardial capacitance over time under an applied electric field.

[0049] A simplified model replaces the cardiomyocyte with an equivalent sphere in the direction of the applied electromagnetic field. In this case, the longitudinal average length r(t) can be regarded as the average contractile radius of the cardiomyocyte. Under the applied electromagnetic field, the capacitance of a cell can be estimated by the following formula:

[0050] C(t) = 4πε0 × r(t)

[0051] r(t) is the equivalent average contractile radius of the cardiomyocyte, i.e., the average longitudinal length, which is a time-varying variable. ε0 is the cell permeability. Generally, the capacitance is also proportional to the average longitudinal length of the cardiomyocyte, and the proportionality coefficient is related to the geometry and permeability of the cardiomyocyte. For simplicity, an equivalent sphere is used as a substitute below for illustration.

[0052] Figure 1 This is a schematic diagram of a two-dimensional abstract model of simulated cardiomyocytes provided in one embodiment of the present invention, which is supported by multiple cardiomyocyte microstructures. Specifically, when the heart cells are in their normal position, since the cardiac structural cells spatially restrict the muscle cells, the cardiomyocytes can be considered to be connected in series and parallel. In an optional embodiment, it is assumed that there are M cells connected in series in the longitudinal direction, and a total of L chains connected in parallel. Simultaneously, in the direction of the applied electromagnetic field, the cardiomyocyte is replaced by an equivalent sphere. In this case, the longitudinal average length r(t) can be considered as the average contraction radius of the cardiomyocyte. Under the applied electromagnetic field, the capacitance of a single cell can be estimated using the following formula:

[0053]

[0054] Where r(t) is the equivalent average contractile radius of the cardiomyocyte, i.e., the average longitudinal length, which is a time-varying variable, and ε0 is the cell permeability. Therefore, under normal conditions, C(t) and r(t) have a linear relationship, meaning the capacitance is directly proportional to the average longitudinal length of the cardiomyocyte, and the proportionality coefficient is related to the geometry and permeability of the cardiomyocyte. Under abnormal conditions, the position and magnitude of r(t) may change, or abnormal cells may have different permeabilities, which will cause changes in C(t) with different patterns of change.

[0055] Figure 2 This is a partial system framework diagram provided by another embodiment of the present invention. Specifically, a human or animal body "20" is connected to the acquisition system "23" via electrodes or contacts "21" and cables "22". In an optional embodiment, the voltage signal modulated by the human or animal body "20" is transmitted to the acquisition system "23" via electrodes or contacts "21", and the acquisition system "23" processes the voltage signal and transmits it to the host 24 for further analysis. In an optional embodiment, the host "24" includes a human-machine interface for receiving or transmitting external commands.

[0056] Figure 3 This is a schematic diagram of the transmission and receiving electrodes provided in another embodiment of the present invention. Specifically, "25" represents the heart tissue within the thoracic cavity of a human or animal body, and both the transmitting electrode "27" and the receiving electrode "26" are located on the skin directly above the heart tissue "25". In an optional embodiment, the transmitting electrode "27" includes two pairs of electrodes "T1" and "T2", and "T3" and "T4". Each pair of transmitting electrodes is time-division driven and independent of each other. Electrodes "T1" and "T2" are respectively aligned with the outer edges of both ends of the heart tissue "25" in the longitudinal direction, and electrodes "T3" and "T4" are respectively aligned with the outer edges of both ends of the heart tissue "25" in the transverse direction. The broadband current signal enters the human or animal body "20" through the transmitting electrode "27"; the receiving electrode "26" includes three electrodes "R1", "R2" and "R3", all aligned with the heart tissue "25" and located between the transmitting electrodes "27", for detecting the broadband voltage signal. In an optional embodiment, electrodes “R1” and “R2” or “R1” and “R3” respectively form a longitudinal receiving pair, and electrodes “R2” and “R3” form a transverse receiving pair. The system may include these two receiving loop pairs for detecting changes in the movement of cardiac tissue in two directions.

[0057] Figure 4This is a schematic diagram of the system circuit structure provided in another embodiment of the present invention. Specifically, the system can not only receive voltage signals, but also transmit current signals to the human or animal body and its tissues. In an optional embodiment, a broadband signal is generated from the frequency domain to the time domain in the integrated circuit (IC) of the microprocessor "1" or the field-programmable gate array (FPGA) "2". If the broadband signals are not frequently updated, their time-domain signals can be stored in the system, and the FPGA "2" can continuously output the signals to the digital-to-analog converter (DAC) "4". In an optional embodiment, to reduce analog distortion, the DAC typically operates at a high speed, for example, more than 16 times the Nyquist rate. The output signal of the DAC "4" is amplified to drive the broadband current pump "9".

[0058] In an optional embodiment, the output of the broadband current pump "9" is connected to the input of the analog switch "11", and the output of "11" is connected to the transmitting electrode pair "T1" and "T2", or "T3" and "T4", respectively. This transmits the current signal to the human or animal body.

[0059] In an optional embodiment, the two pairs of receiving electrodes "R1, R2" or "R1, R3" can receive signals along the long axis of the heart simultaneously or not simultaneously. Simultaneously, the pair of receiving electrodes "R2, R3" can receive signals along the short axis of the heart.

[0060] In an optional embodiment, the voltage signal modulated by a human or animal body is amplified by a preamplifier array "10". The outputs of the preamplifier array "10" are all input to a broadband amplifier array "8", one of which is also connected to a dedicated ECG amplification acquisition unit "7" to obtain an ECG signal, which is then sent to the FPGA "2". The broadband amplifier array "8" outputs the signal to an analog-to-digital converter (ADC) "6", which in this embodiment employs a high-speed and high-resolution ADC. The ADC "6" then converts the analog signal into a digital signal and sends it to the FPGA "2".

[0061] In an optional embodiment, changes in the human cardiovascular system can cause a 0.2% impedance change, i.e., a dynamic range of approximately -54 dB. If the received signal requires 1% resolution, the required dynamic range is 94 dB, approximately 16 bits. Therefore, the minimum requirement for the digital-to-analog converter used in this embodiment is 16 bits.

[0062] In an alternative embodiment, since the analog filter will alter the phase response, digital correction must be performed to calculate the human body phase response. Therefore, this embodiment does not use an analog filter, but instead uses an oversampling DAC, whose high speed will greatly reduce the dependence on the analog filter. The oversampling rate can be 16 times the Nyquist rate or higher.

[0063] In an optional embodiment, signal acquisition has higher requirements than signal generation. However, oversampling, like with a DAC, places high demands on hardware performance and resources, and the effect is not significant for modulated signals. Therefore, this embodiment uses a trigonometric integrator ADC for signal acquisition. It requires superposition and has a low sampling rate. Specifically, the bit resolution decreases as the sampling rate increases. In an optional embodiment, due to human differences, the dynamic range of the ADC needs to be considered. Approximately 3 bits are reserved for this variation, while at least one bit margin is retained to prevent saturation. In specific implementation, to maintain the same dynamic range as a DAC, the ADC will have a minimum of 20 bits, thus a full-speed 24-bit trigonometric integrator ADC has a dynamic range of approximately 20 bits.

[0064] Figures 5a-5d This is a flowchart of a method provided in another embodiment of the present invention, specifically including signal generation, signal acquisition, and signal processing. In optional embodiments, such as... Figure 5a As shown, the signal generation includes generating a multi-frequency synchronous orthogonal sinusoidal digital signal from the frequency domain to the time domain S511, converting the digital signal into an analog signal S512, amplifying the analog signal to drive a current pump S513, converting the voltage signal into a current signal S514, and injecting the multi-frequency synchronous orthogonal sinusoidal current into the human or animal body under test S515.

[0065] In optional embodiments, such as Figure 5b As shown, signal acquisition specifically includes receiving an analog voltage signal from a human or animal body S521 and amplifying it S522, and converting the analog signal into a digital signal S523.

[0066] In optional embodiments, such as Figure 5c As shown, after signal acquisition, a Fourier transform is performed to convert the signal from the time domain to the frequency domain to obtain a broadband frequency response S531, which is time-varying. These frequency responses are then frequency-corrected and filtered to eliminate distortion and noise S532-S534. These corrected and filtered frequency responses are used to calculate the system transfer function S535, which is also a time-varying sequence. Based on the coefficient decomposition of the system transfer function, we can obtain the heart resistance and capacitance S536. The resistance and capacitance sequence is then filtered for the next stage of processing S537. That is, the heart capacitance is directly related to the size of the cardiomyocytes.

[0067] In optional embodiments, such as Figure 5d As shown, the capacitor also contains geometric information, which should be removed in S541. In this embodiment, the time derivative of the capacitor is divided by the capacitance fluctuation over one cardiac cycle, i.e., dc / dt / Δc. This method is dependent on specific parameters. For example, in... Figure 13d and Figure 14dIn this model, after removing geometric information, only information about changes in the radius of myocardial cells remains. This represents the changes in myocardial cells during the cardiac cycle. Further analysis and machine learning (S542) can be performed based on this. Cardiac electrical resistance is more complex, including the resistance of blood in the ventricles, atria, and myocardial tissue. However, since changes in blood flow within the heart are dominant, resistance can be directly used to calculate blood flow.

[0068] Figures 6a-6d This is another embodiment of the invention providing electrocardiogram, cardiac resistance, and capacitance curves over time for a young male, as well as the derivative of the capacitance curve. This is data from a normal individual. Specifically, Figure 6a It's an electrocardiogram (ECG). Figure 6b It is a heart resistance curve. Figure 6c It is a myocardial capacitance curve. Figure 6d It is a curve showing the change in the derivative of myocardial capacitance.

[0069] In an optional embodiment, the electrocardiogram (ECG) is not a standard format but is obtained by simultaneous detection on electrodes measuring cardiac voltage signals. Cardiac resistance originates from blood in the chambers and myocardial tissue. At the end of diastole, the chambers have the largest blood volume and the lowest resistance. The opposite is true at the end of systole. This perfectly matches actual data, so the displayed cardiac resistance should be dominated by blood resistance. At the end of diastole, myocardial cells relax and have the largest cell volume. Therefore, capacitance reaches its peak. At the end of systole, myocardial cells are at their smallest volume and capacitance is at its smallest. The capacitance curve does not completely recover to the maximum diastolic level during this cardiac cycle. This could be due to two reasons: first, interference; second, the diastolic process is also random. Not every cycle is the same, and not all recover to the maximum position; some are larger than others. Looking at the cardiac resistance curve, the heart volume decreases from the R wave (contraction) to the T wave and then begins to increase (diastole). This perfectly matches the polarization and depolarization of the myocardium's bioelectrical activity. From his cardiac capacitance curve, the myocardial cells begin to shrink (contract) during the R wave and begin to enlarge (dipate) at the end of the T wave. It does not return to the maximum diastolic point, which is due to the randomness of cardiac diastole. The pumping activity and work done by the heart can be estimated from the volume of the heart and the changes in the volume of the myocardial cells; that is, the characteristics of the mechanical activity of biological tissue can be estimated based on its electrical activity.

[0070] Figures 7a-7d This is data from a normal middle-aged male provided in another embodiment of the present invention, wherein, Figure 7a It's an electrocardiogram (ECG). Figure 7b It is a heart resistance curve. Figure 7c It is a myocardial capacitance curve. Figure 7d It is the derivative of the myocardial capacitance curve. By comparison... Figures 7a-7d and Figures 6a-6d It can be observed that, Figures 7a-7d The onset of increased cardiomyocyte volume (diastole) occurs at the peak of the T wave, compared to... Figures 6a-6d This is earlier than expected. It suggests that with increasing age, the elasticity of the myocardium decreases, the systolic period shortens, and the onset of diastole occurs earlier and earlier. In this test subject, myocardial diastole fully recovered within this cycle.

[0071] Figures 8a-8d This is data on an elderly woman provided in another embodiment of the present invention, wherein, Figure 8a It's an electrocardiogram (ECG). Figure 8b It is a heart resistance curve. Figure 8c It is a myocardial capacitance curve. Figure 8d This is the derivative of the myocardial capacitance curve. The subject had high blood pressure and premature ventricular contractions (PVCs). The resistance curve shows that the subject's heart contracted normally, but completed the contraction very early, before myocardial repolarization. After repolarization, the heart volume did not change significantly during this cycle; there was little blood filling. The capacitance curve shows that the myocardium contracted very early, before the T wave, and began to relax, but very slowly, not returning to its maximum relaxation point. The heart contracted too quickly and relaxed too slowly. This suggests myocardial tissue aging.

[0072] Figures 9a-9d This is data on an elderly woman provided in another embodiment of the present invention, wherein, Figure 9a It's an electrocardiogram (ECG). Figure 9b It is a heart resistance curve. Figure 9c It is a myocardial capacitance curve. Figure 9d This is the derivative of the myocardial capacitance curve. Looking at the resistance curve, the heart's contraction relative to the R wave lags significantly, meaning the left ventricular pressure is insufficient, the aorta cannot open, and no blood is ejected. Then the aorta opens, blood flow to the heart decreases, and contraction completes slightly before the T wave peak. Then normal filling occurs. Looking at the capacitance curve, the onset of myocardial contraction is normal, but the myocardium appears weak, with minimal change in myocardial cell volume, increasing later. Myocardial relaxation ends at the T wave and returns to the maximum diastolic point. This shows that the minimum heart volume and the minimum myocardial volume are not necessarily at the same time point.

[0073] Figures 10a-10d This is data on an elderly woman provided in another embodiment of the present invention, wherein, Figure 10a It's an electrocardiogram (ECG). Figure 10b It is a heart resistance curve. Figure 10c It is a myocardial capacitance curve. Figure 10dThis is the derivative of the myocardial capacitance curve. From the resistance curve, the subject's heart volume contraction lags behind the R wave, completing slightly shortly after the T wave peak. Then filling begins, but the filling is severely delayed. From the capacitance curve, the onset of myocardial contraction is normal, and the contraction process is generally normal, reaching its minimum slightly shortly after the T wave. However, myocardial relaxation is severely delayed, but eventually recovers to its normal state.

[0074] Figures 11a-11d This is data on an elderly woman provided in another embodiment of the present invention, wherein, Figure 11a It's an electrocardiogram (ECG). Figure 11b It is a heart resistance curve. Figure 11c It is a myocardial capacitance curve. Figure 11d This is the derivative of the myocardial capacitance curve. Looking at the resistance curve, cardiac contraction is slightly delayed, completing before the T-wave peak, followed by diastole. Looking at the capacitance curve, the onset of myocardial contraction is normal, but the contraction is divided into two regions, which is more clearly visible on the capacitance derivative curve. Therefore, the state of myocardial cells is uneven. Myocardial cells can also relax and recover. This can indicate a defect in the subject's myocardium.

[0075] Figures 12a-12d This is data on an elderly woman provided in another embodiment of the present invention, wherein, Figure 12a It's an electrocardiogram (ECG). Figure 12b It is a heart resistance curve. Figure 12c It is a myocardial capacitance curve. Figure 12d This is the derivative of the myocardial capacitance curve. Looking at the resistance curve, the onset of cardiac contraction is normal, and the T wave is not prominent. The subject's cardiac contraction is divided into two parts; this cardiac cycle did not reach maximum contraction. The onset of myocardial cell contraction is normal. However, the myocardial cell contraction is divided into two phases, with inconsistent contraction, indicating that the myocardial cells cannot coordinate their work. Diastole is severely delayed, but it can still recover to its maximum state. It can be determined that the subject has heart disease.

[0076] Figures 13a-13d and Figures 14a-14d These are data from two individuals provided in another embodiment of the present invention. Figure 13a and Figure 14a It's an electrocardiogram (ECG). Figure 13b and Figure 14b It is a heart resistance curve. Figure 13c and Figure 14c It is a myocardial capacitance curve. Figure 13d and Figure 14d It is a time curve showing the relative rate of change of myocardial capacitance. Figure 13d and Figure 14d The graphs show the changes in ECG, capacitance, and resistance over time, as well as the isomorphic deformation rate (S) of cardiomyocytes. -1 () or the relative rate of change of capacitance Defined as:

[0077]

[0078] dc(t) / dt is the time derivative of the capacitance, c pp It is the peak-to-peak value of the capacitance during this cardiac cycle.

[0079] Or the relative change in capacitance ε is defined as:

[0080]

[0081] Δc(t) is the capacitance difference at two time points.

[0082] As can be seen from the figure, the changes in heart volume and cardiomyocyte volume in a normal person are completely consistent. (Isomorphic deformation rate of cardiomyocytes (s)) -1 The relative rate of change of capacitance in this embodiment and the relative change of capacitance are two measurement parameters.

[0083] Figures 15a-15d and Figures 16a-16d These are data from two normal individuals provided in another embodiment of the present invention. Figure 15a and Figure 16a It's an electrocardiogram (ECG). Figure 15b and Figure 16b It is a heart resistance curve. Figure 15c and Figure 16c It is a myocardial capacitance curve. Figure 15d and Figure 16d This is a time curve showing the relative rate of change of myocardial capacitance. As shown in the figure, the circles mark the moments when the heart volume is at its minimum, and the solid dots mark the moments when the myocardial cell volume is at its minimum. In normal human myocardial tissue movement, the circles and solid dots largely overlap. The "ρ" in the myocardial capacitance curve, representing the relative change of myocardial capacitance, is defined as the capacitance value at the moment of minimum heart volume minus the minimum capacitance, then divided by the peak-to-peak capacitance value of that cardiac cycle, as follows:

[0084]

[0085] Wherein, c(t) circle ) is the capacitance at the moment when the heart volume is at its smallest, c(t) dot ) is the capacitance at the moment when the myocardial volume is at its minimum, c pp This represents the peak-to-peak value of the capacitance during this cardiac cycle. The relative change in myocardial capacitance corresponds to the tensor change in ultrasound. In ultrasound, during aortic valve closure, the isomorphic deformation (%) and isomorphic deformation rate (s) of the tissue are also detected. -1Although this embodiment does not provide direct information on aortic valve closure, the moment of minimum heart volume (maximum resistance) can be considered the moment of aortic valve closure. The relative rate of change of capacitance (s) is measured at this moment. -1 It should be the same deformation rate (s) as in ultrasound testing. -1 The results show a good agreement, with both approaching zero. The relative change in capacitance (%) measured at this time point should also agree with the tensor deformation observed in ultrasonic testing, both approaching zero. The maximum isotropic deformation rate (s) during the contraction phase in ultrasound... -1 For normal people, it is 1 (s) -1 In other words, at the moment of minimum heart volume or maximum resistance, the relative change in capacitance (ρ) and the constant rate of deformation (s) -1 The relative change in capacitance (ρ) approaches 0. The tensor deformation at the moment of aortic closure in Doppler ultrasound tissue imaging corresponds to this change.

[0086] In an optional embodiment, with the help of high sampling rate and high precision, this embodiment can obtain more information. For example, by using waveform analysis, combined with the P, R, and T waves in the electrocardiogram, and combined with statistical models, as well as the curve characteristics of resistance and capacitance, the elasticity of tissues can be analyzed from the perspective of deformation mechanics. That is, the process of contraction and expansion of the longitudinal average length of myocardial cells can be analyzed, such as the contraction speed and expansion speed, to calculate the elasticity and work capacity of the myocardium.

[0087] Figures 17a-17d This is data from a person with a heart tissue abnormality provided in another embodiment of the present invention. Figure 17a It's an electrocardiogram (ECG). Figure 17b It is a heart resistance curve. Figure 17c It is a myocardial capacitance curve. Figure 17d This is a time curve showing the relative rate of change of myocardial capacitance. The circles in the graph mark the moments when the heart volume is at its minimum, and the solid dots mark the moments when the myocardial cell volume is at its minimum. Based on calculations, "ρ" (27%) and... The results (-5.67) all indicated abnormalities in the cardiac tissue.

[0088] Figures 18a-18d This is data from a person with a heart tissue abnormality provided in another embodiment of the present invention. Figure 18a It's an electrocardiogram (ECG). Figure 18b It is a heart resistance curve. Figure 18c It is a myocardial capacitance curve. Figure 18d This is a time curve showing the relative rate of change of myocardial capacitance. The circles in the graph mark the moments when the heart volume is at its minimum, and the solid dots mark the moments when the myocardial cell volume is at its minimum. Calculations show that the result of "ρ" (22%) indicates an abnormality in the cardiac tissue, while... The result of (-2.6) indicates a slight abnormality in the cardiac tissue.

[0089] Figures 19a-19d This is data from a person with a heart tissue abnormality provided in another embodiment of the present invention. Figure 19a It's an electrocardiogram (ECG). Figure 19b It is a heart resistance curve. Figure 19c It is a myocardial capacitance curve. Figure 19d This is a time curve showing the relative rate of change of myocardial capacitance. The circles in the graph mark the moments when the heart volume is at its minimum, and the solid dots mark the moments when the myocardial cell volume is at its minimum. Calculations show that the result of "ρ" (23%) indicates an abnormality in the cardiac tissue. The result of (-0.9) indicates that the heart tissue is basically normal.

[0090] Figures 20a-20d This is data from a person with a heart tissue abnormality provided in another embodiment of the present invention. Figure 20a It's an electrocardiogram (ECG). Figure 20b It is a heart resistance curve. Figure 20c It is a myocardial capacitance curve. Figure 20d This is a time curve showing the relative rate of change of myocardial capacitance. The circles in the graph mark the moments when the heart volume is at its minimum, and the solid dots mark the moments when the myocardial cell volume is at its minimum. Calculations show that the result of "ρ" (17%) indicates an abnormality in the cardiac tissue. The result of (-0.45) indicates that the cardiac tissue is basically normal.

[0091] The foregoing description describes specific embodiments. Those skilled in the art can make various changes and modifications without departing from the inventive concept. The scope of this invention is not limited to the contents of the specification but is determined by the scope of the claims.

Claims

1. A non-invasive method of measuring a characteristic of myocardial tissue motion, characterized by, The method comprises: transmitting the generated multiple synchronous quadrature periodic alternating currents of different frequencies and phase controllable adjustable to the living body to generate multiple synchronous periodic alternating voltage signals of different frequencies; receiving the periodic alternating voltage signals modulated by the cardiac tissue changes in the living body to obtain the frequency response of the living body; calculating the resistance and capacitance of the cardiac tissue according to the frequency response; estimating the motion characteristics of the myocardial tissue according to the resistance and capacitance, wherein the calculating the resistance and capacitance of the cardiac tissue according to the frequency response comprises obtaining the system transfer function of the living body according to the frequency response, and performing multi-chamber modeling to separate the cardiac tissue and the peripheral tissue.

2. The method of claim 1, wherein, The estimating the motion characteristics of the myocardial tissue according to the resistance and capacitance comprises: calculating the longitudinal average length of the myocardial cells and the changes thereof according to the capacitance, and / or calculating the cardiac blood pumping flow according to the resistance; and obtaining the longitudinal elasticity state of the whole heart according to the longitudinal average length of the myocardial cells and the changes thereof and / or the cardiac blood pumping flow.

3. The method of claim 2, wherein, The method further comprises estimating the working state of the heart and the myocardium according to the longitudinal elasticity state of the whole heart.

4. The method of claim 3, wherein, The estimating comprises analyzing the health state and working state of the heart and the myocardium according to the slope value of the changes of the longitudinal elasticity state of the whole heart, the delay to the R wave, the peak-to-peak value, the shape of the curve of the changes of the longitudinal average length of the myocardial cells and the derivative thereof, the working state of the heart and the myocardium including the contraction speed, time, strength and mode of the cardiac tissue, and / or the diastolic speed, time, recovery and mode of the cardiac tissue.

5. The method of claim 1, wherein, The obtaining the frequency response of the living body comprises calculating the frequency response estimation value of the wideband frequency once every 0.25 to 5 milliseconds.

6. The method of claim 2, wherein, The calculating the longitudinal average length of the myocardial cells and the changes thereof according to the capacitance comprises: detecting the longitudinal average length of the myocardial cells and the changes thereof over time at a rate of 200 to 4000 times per second; processing the time sequence of the longitudinal average length of the myocardial cells over time using a digital signal processing method, the digital signal processing method including digital filtering, fast Fourier transform (FFT), and time domain and frequency domain analysis.

7. The method of claim 6, wherein, The method further comprises referring to an electrocardiogram with the same time sequence to analyze the sequence of the changes of the longitudinal average length of the myocardial cells, the referring including comparing the cardiac cycle, the systolic phase and the diastolic phase of the electrocardiogram and the sequence of the changes of the longitudinal average length of the myocardial cells, and / or the boundaries of the cardiac cycle, the systolic phase and the diastolic phase.

8. The method of claim 1, wherein, The performing multi-chamber modeling to separate the cardiac tissue and the peripheral tissue comprises modeling each chamber by a parallel resistance and capacitance, and connecting multiple chambers in series or in parallel.

9. A system for implementing any of the methods of claims 1-8, characterized by The system comprises a terminal and at least one processor, wherein the terminal comprises: a generator for generating multiple synchronous quadrature periodic alternating currents of different frequencies and phase controllable adjustable; one or more sensors for transmitting the periodic alternating current into the living body to generate a plurality of periodic alternating voltage signals of different frequencies, and receiving the periodic alternating voltage signals modulated by changes in cardiac tissue in the living body to obtain a frequency response of the living body; the processor is configured to calculate the resistance and capacitance of the cardiac tissue according to the frequency response, and estimate the motion characteristics of the myocardial tissue according to the resistance and capacitance.

10. The system of claim 9, wherein, the sensors are configured to collect single or multiple data from different parts.

11. The system of claim 9, wherein, The system further comprises a database for storing the processing results and data of the processor, and the processor can retrieve the database.

12. The system of claim 9, wherein, The processor can be remote, and the system can be observed in real time mode.

13. The system of any of claims 9-12, wherein, The terminal further comprises a human-computer interface for controlling the system and / or displaying the results.

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