A pressure-volume loop mapping method with real-time feedback

Abstract

The present application relates to the biomedical field, specifically relates to a kind of pressure-volume loop drawing method with real-time feedback, comprising the following steps: S1: ECG data, ultrasonic data and non-invasive blood pressure data are collected and integrated into integrated processor input;S2: by integrated processor, left ventricular area time series data is extracted, left ventricular volume is measured, cardiac cycle is positioned and the processing of volume-pressure coordinate is calculated;S3: according to the data dynamically drawn PV loop after processing, and the corresponding index of PV loop is extracted.The beneficial effects of the present application are: by simultaneously connecting ECG data and ultrasonic data integrated processor for data transmission, avoid the delay that may exist in transmission process, realize the automatic phase alignment of ECG data and ultrasonic data, then divide the start and end point of the cardiac cycle of the aligned ultrasonic data by automatically identifying R wave starting point, ensure the accuracy of cardiac cycle division, meet the precondition of dynamic PV loop drawing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure-volume loop, in particular to a pressure-volume loop drawing method with real-time feedback. BACKGROUND

[0002] The pressure-volume loop (PV loop) of the left ventricle is a two-dimensional graph of the instantaneous relationship between pressure and volume during a cardiac cycle. By analyzing the PV loop, the heart function, hemodynamics, and ventricular arterial coupling can be evaluated under normal and pathological conditions. Otto Frank first described the cardiac cycle and ventricular characteristics through the window of the PV loop in 1895. Subsequently, Suga and Sagawa introduced a method for real-time measurement of the PV loop in an isolated blood-perfused heart, which led to a large number of studies on cardiac mechanics and energetics through the PV loop. As the gold standard for intuitive and real-time assessment of cardiac function, the PV loop contains a wealth of information about cardiac function, such as systolic function, diastolic function, preload, afterload, stroke volume, myocardial energy consumption, etc. In particular, the end-systolic and end-diastolic pressure-volume relationships (ESPVR and EDPVR, respectively) are the focus of numerous studies.

[0003] For most clinical scenarios, especially anesthesia management during the perioperative period, the PV loop has unique advantages. First, based on the PV loop, a large number of cardiac function indicators can be calculated simultaneously, such as the gold standard for reflecting systolic function: end-systolic elastance (Ees), and the gold standard for reflecting preload: end-diastolic volume (EDV), etc., thereby simplifying the preoperative and postoperative evaluation process, and achieving comprehensive monitoring during surgery, replacing the measurement of indirect indicators such as ejection fraction (EF) and cardiac output (CO); secondly, the PV loop can dynamically and real-time reflect the entire process of the cardiac cycle, and accurately identify which physiological link is problematic. For example, CO monitoring can reflect the pumping function of the heart, but if CO decreases, it is difficult to determine which link, preload, contractility, or afterload, is problematic, while the PV loop can locate the abnormal physiological link through indicators such as Ees and EDV, and guide clinical precise intervention; more importantly, the PV loop can reveal early compensatory performance of the heart, guide early intervention, and avoid adverse events. For example, blood pressure is the most commonly used monitoring indicator during the perioperative period, but the trend of blood pressure is easily affected by compensatory mechanisms and has significant lag, and only when there is a serious decompensation of systemic or local perfusion will a low blood pressure warning state be shown on the blood pressure. Although the low blood pressure can be corrected through intervention, a large number of studies have confirmed that the occurrence of intraoperative hypotension is significantly associated with adverse outcomes. Therefore, only if the decompensation is detected early and intervened in time, can adverse events be avoided and patient outcomes be improved.

[0004] The traditional PV loop is drawn by measuring the intraventricular pressure and volume at the same time in a single heartbeat, and relies on invasive measurement, which is difficult to achieve in daily clinical application. The two most commonly used non-invasive PV loop analysis methods are based on cardiovascular magnetic resonance (CMR) imaging and brachial artery blood pressure, and Doppler echocardiography and brachial artery blood pressure, both of which are essentially based on left ventricular volume-time curve and time-varying elastic model to draw PV loop, the former has higher accuracy of left ventricular volume measured by CMR device, but the operation is complex, and the real-time performance and convenience are poor; the latter can be measured simply by bedside ultrasound, and the cost is lower and more portable, but the accuracy of the data depends on the image quality, and the stability is poor, and the error is large.

[0005] Whether based on CMR or bedside echocardiography to draw PV loop, both of them cannot achieve real-time and long-time continuous monitoring, the former needs to collect data for a long time and perform offline analysis through post-processing, and cannot obtain the PV loop change of the patient in real time; the latter can theoretically perform real-time measurement, but needs to manually extract the parameters in the echocardiogram and substitute them into the time-varying elastic model, which has manual lag, and continuous measurement consumes a lot of manpower, and it is difficult to maintain long-time and stable image measurement, and does not have clinical feasibility. In addition, continuous drawing of PV loop of multiple cardiac cycles needs to divide the start and end points of different cardiac cycles, and pure left ventricular volume-time curve cannot achieve accurate segmentation, so the current non-invasive method cannot meet the real-time, continuous and dynamic long-time monitoring of PV loop of patients in the perioperative period. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a pressure-volume loop drawing method with real-time feedback.

[0007] The purpose of the present application is achieved by the following technical solution: a pressure-volume loop drawing method with real-time feedback, comprising the following steps:

[0008] S1: collecting and integrating ECG data, ultrasound data and non-invasive blood pressure data into an integrated processor;

[0009] S2: extracting left ventricular area-time sequence data, measuring left ventricular volume, positioning cardiac cycle and calculating volume-pressure coordinate by the integrated processor;

[0010] S3: dynamically drawing the PV loop according to the processed data, and extracting the corresponding indicators of the PV loop.

[0011] Preferably, in step S2, extracting left ventricular area-time sequence data further comprises the following steps:

[0012] A1: inputting the left ventricular short-axis cross-sectional image collected by the wearable ultrasound device into the integrated processor;

[0013] A2: Extract the left ventricular short-axis real-time area by an automatic segmentation algorithm, and generate left ventricular area time series data with corresponding accuracy according to the image frame rate;

[0014] A3: Data smoothing is performed by using a natural spline function, and higher-precision area time series data is extracted.

[0015] Preferably, in step S2, measuring the left ventricular volume further comprises the following steps:

[0016] B1: Collect long-axis images of several cardiac cycles on the parasternal left ventricular long-axis section by a wearable ultrasonic probe, and transmit them to an integrated processor;

[0017] B2: Extract the left ventricular long-axis inner diameter by an image enhancement algorithm and an automatic segmentation algorithm, and obtain length time series data;

[0018] B3: Perform data smoothing processing by using a natural spline function, extract higher-precision length data, and calculate the average left ventricular length time series data of each cardiac cycle;

[0019] B4: Obtain left ventricular volume time series data,

[0020] ;

[0021] wherein, is the volume of the left ventricle, is the short-axis area of the left ventricle, is the long-axis length of the left ventricle.

[0022] Preferably, in step S2, positioning the cardiac cycle is specifically: the ECG data automatically identifies the R wave signal of each cardiac cycle based on an electrocardiogram algorithm, and divides the left ventricular volume curve into different cardiac cycle subsequences according to the time corresponding to the starting point of the R wave signal; the non-invasive blood pressure data is transmitted to the integrated processor through Bluetooth, and the corresponding systolic pressure and diastolic pressure are automatically extracted based on the start and end time of each cardiac cycle.

[0023] Preferably, in step S2, the volume-pressure coordinates of multiple cardiac cycles at equal intervals are calculated based on a normalized time-varying elastic model.

[0024] Preferably, the parameters used by the normalized time-varying elastic model include volume, ejection fraction, cardiac output, systolic pressure, diastolic pressure, and normalized time.

[0025] The present application has the following advantages:

[0026] 1、The present application avoids the possible delay in the transmission process by connecting the ECG data and the ultrasound data to the integrated processor for data transmission at the same time, realizes the automatic phase alignment of the ECG data and the ultrasound data, and then divides the start and end points of the cardiac cycle of the aligned ultrasound data through automatic identification of the R-wave starting point, thereby guaranteeing the accuracy of the cardiac cycle division and meeting the precondition of dynamic PV loop drawing.

[0027] 2、The present application acquires continuous and stable ultrasound images through data acquisition by the wearable ultrasound device, and the continuous measurement time can be more than 24 hours, almost covering the intraoperative monitoring time length of all categories of non-cardiac surgery, and the integrated processor adopts an automatic mode for image and data analysis, thereby guaranteeing the real-time and continuity. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the pressure-volume loop drawing method process. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0031] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0032] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0033] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the present application is used, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "mount", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] In this embodiment, as shown in Figure 1 A pressure-volume loop drawing method with real-time feedback includes the following steps:

[0036] S1: Collecting and integrating ECG data, ultrasound data and non-invasive blood pressure data into an integrated processor;

[0037] S2: Extracting left ventricular area-time sequence data, measuring left ventricular volume, positioning the cardiac cycle and calculating the volume-pressure coordinate by the integrated processor;

[0038] S3: Dynamically drawing a PV loop according to the processed data, and extracting corresponding indicators of the PV loop. Specifically, since part of the parameters required by the model need complete cardiac cycle data for calculation, the PV loop drawn by the present application is real-time dynamic data lagging one cardiac cycle. The main output graphic data in step S3 includes ECG curve, left ventricular area-time curve and dynamic PV loop, and the main output numerical data includes a series of perioperative clinical indicators such as continuous blood pressure, Ees, CO and Ea. By connecting the ECG data and the ultrasound data to the integrated processor for data transmission at the same time, the delay that may exist in the transmission process is avoided, the automatic phase alignment of the ECG data and the ultrasound data is realized, and the starting and ending points of the aligned ultrasound data cardiac cycle are divided by automatically identifying the R-wave starting point, so as to ensure the accuracy of the cardiac cycle division and meet the precondition of dynamic PV loop drawing.

[0039] Further, in step S2, extracting the left ventricular area-time sequence data further includes the following steps:

[0040] A1: inputting the left ventricular short-axis cross-section image collected by the wearable ultrasound device into the integrated processor, and improving the boundary contrast of the image through an image enhancement algorithm;

[0041] A2: extracting the left ventricular short-axis real-time area through an automatic segmentation algorithm, and generating left ventricular area-time sequence data with corresponding accuracy according to the image frame rate;

[0042] A3: performing data smoothing using a natural spline function to extract higher-precision area-time sequence data. Specifically, data is collected by the wearable ultrasound device to obtain continuous and stable ultrasound images, and the continuous measurement time can be more than 24 hours, almost covering the intraoperative monitoring time of all categories of non-cardiac surgery. The integrated processor uses an automated mode to perform image and data analysis, ensuring real-time and continuity.

[0043] Further, in step S2, measuring the left ventricular volume further includes the following steps:

[0044] B1: collecting a plurality of long-axis images of a cardiac cycle through the wearable ultrasound probe on the parasternal left ventricular long-axis section (actually adjusting the long-axis section to fully expose the apex in the image range), and transmitting the images to the integrated processor;

[0045] B2: extracting the left ventricular long-axis inner diameter (the length from the apex to the mitral valve) through an image enhancement algorithm and an automatic segmentation algorithm to obtain length-time sequence data;

[0046] B3: performing data smoothing processing through a natural spline function to extract higher-precision length data, and calculating the average left ventricular length-time sequence data of each cardiac cycle;

[0047] B4: obtaining left ventricular volume-time sequence data,

[0048] ;

[0049] wherein, is the volume of the left ventricle, is the short-axis area of the left ventricle, is the long-axis length of the left ventricle. Specifically, the traditional method is to calculate the volume based on the length-area method of the four-chamber section, but it assumes that the cross-section of the left ventricle is circular, and uses the diameter to calculate the area, which is an approximation. The present application uses the left ventricular short-axis section, and identifies the irregular left ventricular short-axis area based on the automatic segmentation algorithm, so the calculation of the volume is more accurate.

[0050] In the present embodiment, in step S2, the positioning of the cardiac cycle is specifically: the ECG data automatically identifies the R wave signal of each cardiac cycle based on an electrocardiogram algorithm, and divides the left ventricular volume curve into different cardiac cycle subsequences according to the time corresponding to the starting point of the R wave signal; the non-invasive blood pressure data is transmitted to the integrated processor through Bluetooth, and the corresponding systolic pressure and diastolic pressure are automatically extracted based on the start and end time of each cardiac cycle. Specifically, since the ECG data and the ultrasound data are connected to the same integrated processor, the measurement delay, packaging delay and transmission delay between different measurement devices are ignored, and the automatic alignment of the ECG curve and the left ventricular volume curve is realized. Compared with the traditional method of dividing the cardiac cycle, which is based on the left ventricular volume curve, the two maximum values between which are a complete cardiac cycle, this is inaccurate, because the left ventricular volume changes exist in the isovolumic contraction period and the isovolumic relaxation period, and due to the frame rate limitation of the ultrasound data, it is difficult to truly capture the plateau period of these two volume changes, and the interpolation algorithm also smooths out this part, so the cardiac cycle division of the traditional method is rough. The present application uses ECG data to assist ultrasound data in positioning the start and end points of different cardiac cycles. First, the frame rate of ECG data is extremely high, which can accurately capture all changes within the cardiac cycle. Second, the ECG data has very obvious start and end point features of the cardiac cycle, that is, the starting point of the R wave represents the starting point of each cardiac cycle. Therefore, by connecting the ECG data and the ultrasound data to the integrated processor for data transmission, the delay that may exist in the transmission process is avoided, the automatic phase alignment of the ECG data and the ultrasound data is realized, and the start and end points of the cardiac cycle of the aligned ultrasound data are divided by automatically recognizing the R wave starting point, ensuring the accuracy of the cardiac cycle division. That is, the four most important feature points in the PV ring, namely the start of the systolic period, the start of the ejection (the start of the isovolumic contraction period), the end of the systolic period (the start of the diastolic period) and the end of the isovolumic relaxation period, are difficult to determine in a separate volume-time curve, but through ECG assisted positioning, the phase of the four feature points can be accurately determined, thereby realizing more accurate drawing of the PV ring.

[0051] Further, in step S2, the volume-pressure coordinates of multiple cardiac cycles are calculated based on the normalized time-varying elastic model. The parameters required by the normalized time-varying elastic model are obtained from the left ventricular volume-time curve and the non-invasive blood pressure time series data, specifically including volume, ejection fraction, cardiac output, systolic pressure, diastolic pressure and normalized time.

[0052] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of the present application.

Claims

1. A method for drawing pressure-volume loops with real-time feedback, characterized in that: Includes the following steps: S1: Collects and integrates ECG data, ultrasound data, and non-invasive blood pressure data into the integrated processor; S2: The integrated processor is used to extract left ventricular area time series data, measure left ventricular volume, locate cardiac cycle, and calculate volume-pressure coordinates. S3: Dynamically draw the PV ring based on the processed data and extract the corresponding indicators of the PV ring; In step S2, extracting the left ventricular area time series data also includes the following steps: A1: Input the short-axis section image of the left ventricle acquired by the wearable ultrasound device into the integrated processor; A2: Extract the real-time area of ​​the short axis of the left ventricle using an automatic segmentation algorithm, and generate time series data of the left ventricle area with corresponding precision based on the image frame rate; A3: Use natural spline functions to smooth the data and extract higher-precision area time series data; In step S2, measuring the left ventricular volume also includes the following steps: B1: Long-axis images of several cardiac cycles are collected in the parasternal left ventricular long-axis section using a wearable ultrasound probe and transmitted to an integrated processor; B2: The long axis inner diameter of the left ventricle was extracted using image enhancement and automatic segmentation algorithms to obtain length time series data; B3: Data smoothing is performed using natural spline functions to extract higher-precision length data, and the average left ventricular length time series data for each cardiac cycle is calculated; B4: Obtain time series data of left ventricular volume. ； in, This refers to the volume of the left ventricle. The area of ​​the minor axis of the left ventricle. This is the length of the major axis of the left ventricle; In step S2, locating the cardiac cycle specifically involves: ECG data automatically identifying the R-wave signal of each cardiac cycle based on the ECG algorithm, and dividing the left ventricular volume curve into different cardiac cycle sub-sequences according to the time corresponding to the start of the R-wave signal; non-invasive blood pressure data is transmitted to the integrated processor via Bluetooth, and the corresponding systolic and diastolic blood pressure is automatically extracted based on the start and end times of each cardiac cycle.

2. The pressure-volume loop plotting method with real-time feedback according to claim 1, characterized in that: In step S2, volume-pressure coordinates at equal intervals for multiple cardiac cycles are calculated based on a standardized time-varying elastic model.

3. The pressure-volume loop plotting method with real-time feedback according to claim 2, characterized in that: The parameters used in the standardized time-varying elasticity model include volume, ejection fraction, cardiac output, systolic blood pressure, diastolic blood pressure, and standardized time.

Images