Method, system, and storage medium for non-invasive continuous assessment of ejection fraction

Abstract

The present application relates to the medical technical field, especially relate to a kind of noninvasive continuous assessment of ejection fraction method, system and storage medium, the method includes: through monitoring device obtains the multiple physiological parameters of the person to be assessed, wherein, multiple physiological parameters include: the stroke volume of the person to be assessed, left ventricular pre-ejection period and pre-ejection period;Then according to formula calculates the ejection fraction of the person to be assessed;Through relevant monitoring device obtains the multiple physiological parameters of the person to be assessed, specifically, stroke volume, left ventricular pre-ejection period and pre-ejection period, then, the ejection fraction of the person to be assessed can be conveniently calculated and obtained according to the formula provided by the present application, since the related parameters for evaluating ejection fraction in the present application can be continuously obtained by noninvasive method, thus the present application provides a kind of noninvasive continuous ejection fraction evaluation method.

Description

Technical Field

[0001] This invention relates to the field of medical technology, and in particular to a method, system and storage medium for non-invasive continuous assessment of ejection fraction. Background Technology

[0002] Heart failure is a serious heart disease associated with impaired cardiac function. It is mainly characterized by blood pooling in the ventricles and not being able to be completely drained, leading to abnormalities in related hemodynamic parameters.

[0003] Left ventricular ejection fraction (LVEF) is the most representative parameter of ventricular function in patients with heart failure. Patients with coronary artery disease undergoing external counterpulsation (EPC) often have heart failure, and heart failure is also an indication for EPC. Therefore, accurate measurement of LVEF is crucial for the clinical diagnosis and treatment of EPC. Currently, EF is commonly used instead of LVEF, and by default, it refers to the ejection fraction of the left ventricle. EF is the percentage of stroke volume relative to the end-diastolic volume of the ventricle, reflecting the adequacy of left ventricular ejection, and it is positively correlated with myocardial contractility.

[0004] In existing technologies, echocardiography is a commonly used method for measuring ejection fraction (EF). However, echocardiography is time-consuming and expensive, the measurement results are not continuous, and the accuracy depends on the operator's experience. Compared with echocardiography, thoracic impedance measurement is simpler and lower cost, making it more suitable for use in the clinical rehabilitation treatment of heart failure patients. Currently, the measurement of stroke volume and cardiac output based on thoracic impedance measurement is clinically accepted, but the accuracy of thoracic impedance measurement of ejection fraction still needs further improvement.

[0005] Existing methods for estimating ejection fraction (EF) using thoracic impedance, such as those developed by Cap et al., have shown that the PEP / LVET ratio has a good correlation with EF, and they have provided a formula for calculating EF using PEP / LVET based on a certain amount of echocardiographic comparative data.

[0006] Jud et al. discovered that (dz / dt) max / Z tot The ratio of Z to EF correlates well, with Z being the most significant. tot This represents the total change in the differential of the impedance;

[0007] Van et al. further improved upon this, believing that (dz / dt) max / Z tot ×LVET or (dz / dt) max / Z tot / HR improves the accuracy of EF estimation to some extent. However, the methods mentioned above for assessing ejection fraction (EF) are somewhat subjective and lack stronger theoretical support. Although they have a certain degree of accuracy in the final trial, they still fall short of clinical requirements. Summary of the Invention

[0008] The purpose of this invention is to provide a method, system, and storage medium for non-invasive continuous assessment of ejection fraction, thereby achieving non-invasive continuous assessment of ejection fraction and further improving the accuracy of ejection fraction assessment using impedance cardiography.

[0009] To achieve the above objectives, the first aspect of the present invention provides a method for non-invasive continuous assessment of ejection fraction, the method comprising:

[0010] Multiple physiological parameters of the subject to be evaluated are obtained through monitoring equipment. These parameters include stroke volume, left ventricular pre-ejection phase, and pre-ejection phase.

[0011] The ejection fraction of the subject to be evaluated is calculated according to the following formula (1):

[0012] EF = k4SV(LVET / PEP) 3 / 2 (1)

[0013] Where EF is ejection fraction, k4 is a constant, SV is stroke volume, LVET is the left ventricular pre-ejection phase, and PEP is the pre-ejection phase.

[0014] Optionally, the ejection fraction of the subject to be evaluated can be calculated according to the following formula (2):

[0015] EF = k4SVi(LVET / PEP) 3 / 2 (2)

[0016] Where SVi = SV / BSA;

[0017] EF is ejection fraction, k4 is constant, SVi is stroke volume index, LVET is left ventricular pre-ejection, PEP is pre-ejection, SV is stroke volume, and BSA is the body surface area of ​​the person being evaluated.

[0018] On the other hand, the present invention also provides a system for non-invasive continuous assessment of ejection fraction, the system including a processor for performing any of the methods described above.

[0019] In another aspect, the present invention also provides a storage medium storing instructions for being read by a machine to cause the machine to perform any of the methods described above.

[0020] Through the above technical solution, multiple physiological parameters of the person to be evaluated can be obtained through relevant monitoring equipment, such as stroke volume, left ventricular pre-ejection phase and post-ejection phase. The ejection fraction of the person to be evaluated can then be conveniently calculated according to the formula provided by this invention. Since the relevant parameters used to evaluate the ejection fraction in this invention can all be obtained non-invasively, and the relevant parameters can be continuously obtained with each heartbeat, this invention provides a non-invasive and continuous ejection fraction evaluation method.

[0021] Furthermore, as can be seen from specific examples of the present invention, the method provided by the present invention is of great significance for improving the accuracy of ejection fraction assessment using impedance cardiography. Compared with existing time-consuming and expensive echocardiography, the method of assessing ejection fraction based on impedance cardiography in the present invention has the advantages of simplicity, low cost and continuity. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating a non-invasive continuous assessment of ejection fraction according to a specific embodiment of the present invention;

[0023] Figure 2 The diagram shown is a schematic representation of the spherical model of the left ventricle in this invention;

[0024] Figure 3 The diagram shows the correlation between several existing ICG methods and ejection fraction (EF); where (a) is the correlation between PEP / LVET and EF value; and (b) is the correlation between CTI / dZ. tot Correlation with EF value; (c) is CTI / dZ tot Correlation between ×LVET and EF value; (d) is CTI / dZ tot ×Correlation between HR and EF value;

[0025] Figure 4 It is shown as SV / BSA / (LVET / PEP) 1.5 Correlation and difference plots between EF and ejection fraction;

[0026] Figure 5 This illustrates the differences between the method provided by the present invention and existing research methods in assessing ejection fraction. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further explained below with reference to specific embodiments.

[0028] As mentioned above, combined with Figure 1 As shown, the present invention provides a non-invasive continuous assessment method for ejection fraction, the method comprising:

[0029] S101. Obtain multiple physiological parameters of the subject to be evaluated through monitoring equipment. Among these parameters, the multiple physiological parameters include: stroke volume, left ventricular pre-ejection phase, and pre-ejection phase.

[0030] S102. Calculate the ejection fraction of the subject to be evaluated according to the following formula (1):

[0031] EF = k4SV(LVET / PEP) 3 / 2 (1)

[0032] Where EF is ejection fraction, k4 is a constant, SV is stroke volume, LVET is the left ventricular pre-ejection phase, and PEP is the pre-ejection phase.

[0033] In a further optimized scheme, considering that the SV of the subjects with larger height and weight is higher, but the EF value of these subjects is generally normal, in order to avoid this problem, the stroke volume index SVi is used instead of SV. Therefore, the ejection fraction of the subjects is calculated according to the following formula (2):

[0034] EF = k4SVi(LVET / PEP) 3 / 2 (2)

[0035] Where SVi = SV / BSA;

[0036] EF is ejection fraction, k4 is constant, SVi is stroke volume index, LVET is left ventricular pre-ejection, PEP is pre-ejection, SV is stroke volume, and BSA is the body surface area of ​​the person being evaluated.

[0037] The following is a detailed description of the inventor's overall concept in this application:

[0038] Based on the introduction in the background section, ejection fraction (EF) is currently commonly used instead of left ventricular ejection fraction (LVEF).

[0039] Those skilled in the art know that the EF value is defined as: (EDV - ESV) / ​​EDV, where EDV is the left ventricular end-diastolic volume and ESV is the left ventricular end-systolic volume. Since EDV - ESV is the stroke volume (SV), the formula for calculating EF can be rewritten as:

[0040] EF = SV / EDV (3)

[0041] The inventors of this application assume that the left ventricle is a regular sphere, such as Figure 2 As shown, r1 and r2 are the left ventricular radii at the end of systole and end of diastole, respectively. Therefore, we can obtain:

[0042]

[0043] For a specific myocardial cell in a ventricle, it moves from point A to point B during the transition from diastole to systole. Assume the distance between A and B is r. m Therefore,

[0044] r1-r2=r m (5)

[0045] We can obtain the following from equations (4) and (5):

[0046]

[0047] The normal EF value for a person is generally between 30% and 70%.

[0048] When EF < 50%, r1 3 / r2 3 <0.5, therefore r m <0.2r1, so r in equation (6) m / 2 is less than 0.1r1, In some

[0049] To simplify the calculation, we can ignore r for now. m The / 2 part is because its contribution to the entire r1 is less than 10%, and also because... The part is greater than 0.9r1, so it can be ignored. In some Therefore, we can obtain:

[0050]

[0051] When the EF value is between 50% and 70%, similarly, we can obtain 0.2r1 < r. m <0.34r1, thus we can obtain,

[0052]

[0053] In summary, r1 can be represented as a principal component, therefore the following formula is used to calculate r1.

[0054]

[0055] Where k1 is a constant, considering r m It is the displacement of myocardial cells during a single cardiac contraction. The displacement time is equal to the ejection time, and the displacement acceleration is related to the cardiac contractility index (CTI) (CTI is 100 × (dz / dt)). max , (dz / dt) maxOriginally, it represents the blood flow acceleration). Considering that the pre-ejection period (PEP) value increases when myocardial contraction is weak, the following formula can be obtained:

[0056]

[0057] Wherein, is the average contractility of myocardial cells, m0 is the mass of myocardial cells, T eject is the ejection time, and k2 is a constant.

[0058] According to the Kubieck formula, for the same subject, (dz / dt) max ×LVET is proportional to the stroke volume (SV). Therefore, the above formula can be modified as:

[0059]

[0060] Wherein, k3 is a constant. According to the definition of left ventricular ejection fraction and equations (4.47) and (4.49), it can be obtained that,

[0061]

[0062] Let The calculation formula for the ejection fraction can be obtained as,

[0063] EF = k4SV(LVET / PEP) 3 / 2

[0064] Currently, the ejection fraction (EF) is usually used to replace the left ventricular ejection fraction (LVEF).

[0065] Then, LVEF = k4SV(LVET / PEP) 3 / 2

[0066] To evaluate the effectiveness of the above model in calculating the ejection fraction (EF), 52 subjects were evaluated. Among them, there were 28 females and 24 males, aged 30 - 90 years. The trial was approved by the Ethics Committee of Hefei High-tech Cardiovascular Hospital (Ethics batch number: 2021 Ethics Review [Medical Device] No. (006)).

[0067] Inclusion criteria: (1) Aged 18 years or above, gender not limited; (2) The subject needs to undergo ejection fraction detection or voluntarily participate in ejection fraction detection; (3) The subject or his / her guardian can understand the research purpose, show sufficient compliance with the research protocol, and sign the informed consent form.

[0068] Exclusion criteria: Patients with chest trauma or chest surgery; Patients with skin allergies to electrode patches; Suspected or confirmed severe aortic valve insufficiency; High-frequency ventilation patients; Patients with extracorporeal circulation assistance, etc.

[0069] During the experiment, the subjects' height and weight were recorded, and HR, CTI, LVET, PEP, and (dz / dt) were recorded using a TL-NiCON-100 device. max / Z tot SV, etc., and EF measured by echocardiography. echo The test results of the 52 subjects are shown in Table 1 below.

[0070] Table 1. Distribution of relevant physiological parameters of 52 subjects

[0071]

[0072] Based on the range of EF, the subjects were divided into 5 groups: EF≥65%, 60%≤EF<65%, 50%≤EF<60%, 40%≤EF<50%, and EF<40%; n is the number of subjects in the current group, and the mean and variance of each measurement data in each group are recorded.

[0073] As mentioned earlier, many researchers use ICG to measure EF. Cap et al. proposed that EF values ​​are negatively correlated with PEP / LVET. Figure 3 As shown in (a), the correlation coefficient r between EF and PEP / LVET is -0.59, and p < 0.001. Therefore, there is a certain correlation between them.

[0074] Jud et al. believe that EF is related to (dz / dt) max / Z tot There is a certain correlation, such as Figure 3 (b) Plotted EF versus (dz / dt) max / Z tot The scatter plot showed a correlation coefficient r of 0.53 and p < 0.001, indicating a certain correlation between the two.

[0075] Van1 and Van2 are improved methods based on Jud, with correlations of 0.55 and 0.61 with EF, respectively, as shown in the figures below. Figure 3 As shown in (c) and 3(d).

[0076] like Figure 4 (a) Display EF and SV / BSA / (LVET / PEP) 1.5 The correlation coefficient was as high as 0.81, and p < 0.001, indicating a stronger correlation compared to existing ICG methods. Figure 4 (b) The Bland-Altman results also show that the EF values ​​measured by this method are in good agreement with those measured by echocardiography. There was only one data point outside the mean ± 1.96σ range, with a mean error of -0.01 and a standard deviation of 6.0, indicating the effectiveness of the method.

[0077] like Figure 5 The differences between the method provided in this invention and existing research methods in assessing ejection fraction were compared, and the results show that the existing ICG method and EF... echo The correlation with the previous method was low, making it unsuitable for determining EF, which confirms the results of Bowling et al. Our method showed a higher correlation with echocardiographic measurements; although the final correlation was only 0.81, it still represents an improvement over existing methods.

[0078] In summary, this invention simplifies the complex relationship between EF value and related ICG parameters by employing a simplified ventricular model, and proposes a method for calculating EF value using these related ICG parameters.

[0079] To demonstrate that the proposed method can prospectively provide EF prediction for patients with unknown cardiac function, it was tested on 52 patients with vascular disease, SV / BSA / (LVET / PEP). 1.5 With EF echo The correlation coefficient reached 0.81, indicating the effectiveness of the proposed method.

[0080] The foregoing has shown and described the basic principles, main features, and characteristics of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A non-invasive, continuous method for assessing ejection fraction, characterized in that, The method includes: Multiple physiological parameters of the subject to be evaluated are obtained through monitoring equipment. These parameters include stroke volume, left ventricular pre-ejection phase, and pre-ejection phase. The ejection fraction of the subject to be evaluated is calculated according to the following formula (1): EF=k4SV(LVET / PEP) 3 / 2 (1) Where EF is ejection fraction, k4 is a constant, SV is stroke volume, LVET is the left ventricular pre-ejection phase, and PEP is the pre-ejection phase.

2. The method according to claim 1, characterized in that, The ejection fraction of the subject to be evaluated is calculated according to the following formula (2): EF=k4SVi(LVET / PEP) 3 / 2 (2) Where SVi = SV / BSA; EF is ejection fraction, k4 is constant, SVi is stroke volume index, LVET is left ventricular pre-ejection, PEP is pre-ejection, SV is stroke volume, and BSA is the body surface area of ​​the person being evaluated.

3. A non-invasive, continuous system for assessing ejection fraction, characterized in that, The system includes a processor for performing the method as described in claim 1 or 2.

4. A storage medium, characterized in that, The storage medium stores instructions that can be read by a machine to cause the machine to perform the method as described in claim 1 or 2.

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