A left ventricular assist device myocardial metabolic product detection system

Abstract

The application discloses a left ventricular assist device myocardial metabolism product detection system and relates to the technical field of medical devices.The system comprises a left ventricular assist device inflow main body, a reference optical fiber module integrated in the side wall of the left ventricular assist device inflow main body, a lactic acid detection module, an NAD(P)H detection module and a signal processing unit, and optical fiber sensing probes of each module are implanted into myocardial tissue.The signal processing unit determines each diastolic low motion moment based on a heart component in a reference light path signal and forms a detection window, extracts a main detection quantity of a lactic acid channel based on SPR resonance wavelength shift and a main detection quantity of an NAD(P)H channel based on a normalized fluorescence signal in the window, mechanically compensates for an ultrahigh frequency interference component of the reference light path, and converts the compensated optical quantity into lactic acid concentration and NAD(P)H relative metabolism index output respectively.The application realizes real-time, continuous and in-situ detection of myocardial deep metabolism products and provides a basis for left ventricular assist device operation state adjustment.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a system, method and electronic device for detecting myocardial metabolites in a left ventricular assist device. Background Technology

[0002] Even with medication, patients with end-stage heart failure may experience persistently low cardiac output, recurrent hospitalizations, or insufficient organ perfusion. While heart transplantation is the cure for end-stage heart failure, donor hearts are limited, making left ventricular assist devices (LVADs) an important means of achieving myocardial recovery or long-term circulatory support.

[0003] The operation of a LVAD is affected by multiple factors, including pump structure, blood characteristics, and cardiac load. When the LVAD's operating power is mismatched with the patient's cardiac function, it may lead to problems such as thrombosis, wall suction events, and hemodynamic abnormalities, which can result in hemolysis, insufficient circulatory support, or even pump failure. Therefore, after LVAD implantation, it is necessary to monitor the myocardial metabolic and load status to provide a basis for adjusting the LVAD's operating status.

[0004] However, existing monitoring methods mainly rely on indirect parameters such as pump motor power and flow estimation, or in vitro examinations such as hematological indicators and echocardiography. They cannot directly reflect the metabolic state of the myocardium and the supply-demand relationship between LVAD power and myocardial demand. Early pump-related abnormalities or circulatory abnormalities are difficult to detect in time, and it is also difficult for clinicians to obtain metabolic indicators of the deep myocardium in real time.

[0005] Fiber optic sensing technology, characterized by miniaturization, high sensitivity, resistance to electromagnetic interference, and multi-parameter detection, offers the possibility of implantable in-situ detection of myocardial metabolites. However, existing fiber optic sensing solutions are mostly validated in in vitro solutions, extracorporeal circulation systems, or isolated heart models, making it difficult to adapt to the dynamic in vivo environment of continuous myocardial contraction, blood flow pulsation, and tissue deformation. Long-term implantation can easily lead to sensitive layer shedding, optical path changes, and signal drift. Furthermore, in vivo detection signals are affected by multiple factors such as tissue scattering, blood flow pulsation, and myocardial contraction, and the optical response of target metabolites is easily masked by background noise. Current technologies lack effective means to quantitatively separate metabolite signals from background noise in a real myocardial environment.

[0006] Therefore, how to achieve real-time, continuous, and in-situ detection of deep myocardial metabolites is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this application is to provide a system, method, and electronic device for detecting myocardial metabolites in a left ventricular assist device (LVAD) to achieve real-time, continuous, and in-situ detection of deep myocardial metabolites, providing a direct basis for adjusting the operating status of the LVAD based on myocardial metabolic status.

[0008] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a left ventricular assist device (LVAD) myocardial metabolite detection system, comprising: a main body of the LVAD inflow tract; a reference fiber optic module, a lactate detection module, and an NAD(P)H detection module integrated into the sidewall of the main body of the LVAD inflow tract, wherein fiber optic sensing probes of the reference fiber optic module, the lactate detection module, and the NAD(P)H detection module are respectively implanted in myocardial tissue; a signal processing unit electrically connected to the reference fiber optic module, the lactate detection module, and the NAD(P)H detection module; wherein, a preset area of ​​the detection optical path of the lactate detection module is provided with an SPR metal coating and a lactate-sensitive layer; the NAD(P)H detection module is used to emit excitation light to the myocardial tissue and collect fluorescence generated by NAD(P)H excitation in the myocardial tissue. The signal processing unit is configured to: determine the diastolic low-motion moment of each heartbeat based on the cardiac component in the reference optical path signal of the reference optical fiber module, and form a detection window; extract the main detection quantities of the lactate channel and the NAD(P)H channel within the detection window, wherein the main detection quantity of the lactate channel is determined based on the SPR resonance wavelength offset, and the main detection quantity of the NAD(P)H channel is determined based on the normalized fluorescence signal; mechanically compensate the main detection quantities of the lactate channel and the NAD(P)H channel using the ultra-high frequency interference component of the reference optical path signal; convert the mechanically compensated optical quantity of the lactate channel into lactate concentration, and convert the mechanically compensated optical quantity of the NAD(P)H channel into NAD(P)H relative metabolic index output.

[0009] In one embodiment, the reference fiber module, the lactate detection module, and the NAD(P)H detection module are integrally cast and encapsulated using medical polyurethane material and respectively embedded in the mounting groove on the side wall of the left ventricular assist device inflow tract main body; the electrical connection lines of each module are led out from below the module, arranged along the wiring cavity formed between the inner and outer walls of the left ventricular assist device inflow tract main body, and led out of the body through a subcutaneous channel together with the electrical connection lines of the left ventricular assist device pump body; the signal processing unit is disposed outside the body and connected to the electrical connection lines led out of the body.

[0010] In one embodiment, the fiber optic sensing probe extends outward from the side wall of the left ventricular assist device inflow tract body (100) and is embedded tangentially or approximately tangentially in the myocardial tissue along the ventricular wall.

[0011] In one embodiment, the reference fiber module includes a broadband micro-LED light source, a reference emitting fiber, a black PEEK light-blocking plate, a reference collecting fiber, and a photodiode. The black PEEK light-blocking plate is disposed between the emitting and collecting regions. The lactic acid detection module includes a broadband micro-LED light source with a center wavelength of 730 nm, an SPR-coated lactic acid detection emitting fiber, a black PEEK light-blocking plate, an SPR-coated lactic acid detection collecting fiber, and a spectral-resolution photoelectric conversion unit. The spectral-resolution photoelectric conversion unit includes a micro-spectral splitter and a high-sensitivity photodetector array. The beam splitter is used to spatially separate the light signals of different wavelengths output from the SPR-coated lactic acid detection and collection fiber. The high-sensitivity photodetector array is used to convert the light signals of different wavelengths into electrical signals to obtain the SPR transmission spectrum. The NAD(P)H detection module includes a 350nm wavelength miniature LED light source, an NAD(P)H emitting fiber, a black PEEK light-blocking plate, an NAD(P)H excitation light collection fiber, a 400nm filter, and a high-sensitivity photodiode. The 400nm filter is disposed between the NAD(P)H excitation light collection fiber and the high-sensitivity photodiode.

[0012] Secondly, this application provides a method for detecting myocardial metabolites in a left ventricular assist device, comprising: acquiring a reference optical path signal, a lactate channel signal, and an NAD(P)H channel signal, wherein the lactate channel signal is acquired by a lactate detection module having an SPR metal coating and a lactate-sensitive layer in a preset area of ​​the detection optical path, and the NAD(P)H channel signal is acquired based on fluorescence generated by NAD(P)H excitation in myocardial tissue; determining the diastolic low-motion moment of each heartbeat based on the cardiac component in the reference optical path signal, and forming a detection window; and extracting lactate from the detection window. The main detection quantities of lactate channel and NAD(P)H channel are determined, wherein the main detection quantity of lactate channel is determined based on SPR resonance wavelength shift, and the main detection quantity of NAD(P)H channel is determined based on normalized fluorescence signal; the main detection quantities of lactate channel and NAD(P)H channel are mechanically compensated using the ultra-high frequency interference component of the reference optical path signal; the mechanically compensated optical quantity of lactate channel is converted into lactate concentration, and the mechanically compensated optical quantity of NAD(P)H channel is converted into NAD(P)H relative metabolic index output.

[0013] In one embodiment, acquiring the reference optical path signal, the lactate channel signal, and the NAD(P)H channel signal includes: performing differential processing on the signal within the time slot of each channel light source by subtracting the average value when the light is on from the average value when the light is off; the main detection quantity of the NAD(P)H channel is determined based on the normalized fluorescence signal, including: calculating the normalized ratio between the fluorescence signal and the reference optical path signal within the same detection window, establishing a patient-specific baseline of the normalized ratio during a stable patient condition, and using the change in the normalized ratio relative to the patient-specific baseline as the main detection quantity of the NAD(P)H channel.

[0014] In one embodiment, the method further includes: performing slow drift compensation on the main detection quantities after mechanical compensation, wherein the slow drift compensation is performed according to the following formula: In the above formula, This is the primary detection quantity for the k-th heartbeat in channel c after slow drift compensation. This is the primary detection quantity for the k-th heartbeat in the c-th channel after mechanical compensation. This is the preset slow drift coefficient for channel c. For the k-th heartbeat, the slowly changing component of the reference optical path within the detection window. .

[0015] In one embodiment, determining the diastolic low-motion moment of each heartbeat based on the cardiac component in the reference optical path signal includes: simultaneously recording at least one of electrocardiogram, cardiac catheterization, and ultrasound during the procedure to determine the patient-specific delay from the reference feature to the target low-motion moment; identifying the reference feature of the k-th heartbeat online, and predicting the diastolic low-motion moment of the k-th heartbeat based on the occurrence time of the reference feature and the patient-specific delay; calculating the correlation between the cardiac component of the current heartbeat and a preset cardiac template, and determining that the corresponding detection window has passed gating when the correlation meets a preset condition; wherein the lactate channel and the NAD(P)H channel are acquired in a time-division manner within the same gated detection window; when the detection window is insufficient to accommodate the complete light source switching cycle of the two channels, the lactate channel and the NAD(P)H channel are acquired alternately in adjacent gated heartbeats.

[0016] In one embodiment, the main detection quantity of the lactic acid channel is determined based on the SPR resonance wavelength shift, including: averaging and normalizing the signals of each pixel in the photosensitive array within the detection window to obtain the corrected array spectrum; determining the integer pixel with the lowest spectral value in the array spectrum within a preset SPR search band; and performing local quadratic curve fitting near the integer pixel, with the fitting formula being: ; Calculate the subpixel resonance position based on the fitted quadratic curve: ;in, Let be the fitted spectral value of the k-th heartbeat, and p be the pixel position. , , The coefficients are obtained from fitting the quadratic curve of the k-th heartbeat. Let be the subpixel resonance position of the kth heartbeat; convert the subpixel resonance position into the SPR resonance wavelength according to the preset pixel-wavelength calibration function, and calculate the offset of the SPR resonance wavelength relative to the reference resonance wavelength.

[0017] Thirdly, this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the method for detecting myocardial metabolites of a left ventricular assist device as described in any of the preceding claims.

[0018] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides a system, method, and electronic device for detecting myocardial metabolites in a left ventricular assist device (LVAD). By integrating a reference fiber optic module, a lactate detection module, and an NAD(P)H detection module into the sidewall of the LVAD's inflow tract, and implanting the fiber optic sensing probes of each module into the myocardial tissue, it enables real-time, continuous, and in-situ detection of lactate and NAD(P)H in the deep myocardium. Simultaneously, a signal processing unit performs diastolic low-motion gating on each heartbeat based on the cardiac component of the reference optical path signal and mechanically compensates for the main detection quantities in both channels using the ultra-high frequency interference component of the reference optical path signal. This achieves quantitative separation of the metabolite optical signal from background noise in an in vivo environment where myocardial contraction, pump vibration, and blood flow pulsation coexist. Compared to existing monitoring methods that rely on indirect parameters such as pump motor power and flow rate estimation, or external examinations such as hematological indicators and echocardiography, this application can directly acquire detection data reflecting the myocardial metabolic state, providing a basis for adjusting the operation of the LVAD and helping to avoid insufficient or excessive unloading. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the module structure of the myocardial metabolite detection system for the left ventricular assist device provided in this application embodiment; Figure 2 This is a schematic diagram of the structure of a reference optical fiber module provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the SPR lactate detection module provided in the embodiments of this application; Figure 4 This is a schematic diagram of the NAD(P)H detection module provided in an embodiment of this application; Figure 5 A schematic flowchart illustrating the method for detecting myocardial metabolites using a left ventricular assist device provided in this application embodiment; Figure 6 This is a graph showing the quantitative comparison results of lactate channels in the experimental examples of this application; Figure 7 This is a continuous signal recording diagram of the lactate channel in the experimental examples of this application; Figure 8 This is a comparison result diagram of the NAD(P)H channel in the experimental example of this application; Figure 9 This is a continuous signal recording diagram of the NAD(P)H channel in the experimental example of this application; Figure 10 This is a scatter plot showing the correlation analysis of paired lactate channel samples in the experimental examples of this application. Figure 11 This is a scatter plot of the correlation analysis of paired NAD(P)H channels in the experimental examples of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Example 1 This embodiment provides a myocardial metabolite detection system for a left ventricular assist device, such as... Figure 1 As shown, it includes a left ventricular assist device inflow tract main body 100, a reference fiber optic module 200, an SPR lactate detection module 300, an NAD(P)H detection module 400, and a signal processing unit 500.

[0023] The reference fiber module 200 is used to acquire reference optical path signals reflecting myocardial motion and optical path disturbances; the SPR lactate detection module 300 is used to detect lactate in myocardial tissue based on the surface plasmon resonance principle; and the NAD(P)H detection module 400 is used to detect NAD(P)H in myocardial tissue based on the fluorescence principle. NAD(P)H is a collective term for NADH and NADPH, both of which fluoresce under excitation light of 340-380nm.

[0024] The signal processing unit 500 is divided into several functional modules according to the signal processing flow. In this embodiment, the signal processing unit 500 includes a differential processing module 501, a diastolic gating module 502, a main detection quantity extraction module 503, a mechanical compensation module 504, a slow drift compensation module 505, and a conversion output module 506. The differential processing module 501 is used to perform lamp-on-lamp differential processing on the three signals output from the reference fiber module 200, the SPR lactate detection module 300, and the NAD(P)H detection module 400 respectively to obtain the reference optical path signal, the lactate channel signal, and the NAD(P)H channel signal; the diastolic gating module 502 is used to determine the diastolic low-motion moment of each heartbeat based on the cardiac component in the reference optical path signal, and form a detection window centered on the diastolic low-motion moment; the main detection quantity extraction module 503 is used to extract the main detection quantities of the lactate channel and the NAD(P)H channel within the detection window, wherein, The main detection quantity of the lactate channel is determined based on the SPR resonance wavelength shift, and the main detection quantity of the NAD(P)H channel is determined based on the normalized fluorescence signal. The mechanical compensation module 504 is used to mechanically compensate for the main detection quantities of the lactate channel and the NAD(P)H channel using the ultra-high frequency interference component of the reference optical path signal. The slow drift compensation module 505 is used to perform slow drift compensation on the main detection quantities after mechanical compensation. The conversion output module 506 is used to convert the compensated optical quantity of the lactate channel into lactate concentration and the compensated optical quantity of the NAD(P)H channel into the NAD(P)H relative metabolic index output.

[0025] like Figures 2 to 4 As shown, the three sensor modules—reference fiber optic module 200, SPR lactate detection module 300, and NAD(P)H detection module 400—are integrated into the side wall of the left ventricular assist device (LVAD) inflow tract main body 100, and are encapsulated to ensure long-term implantation reliability. In this embodiment, the reference fiber optic module 200, SPR lactate detection module 300, and NAD(P)H detection module 400 are integrally cast and encapsulated using medical polyurethane material. Three mounting slots 101 are provided on the side wall of the LVAD inflow tract main body 100, and the reference fiber optic module 200, SPR lactate detection module 300, and NAD(P)H detection module 400 are respectively embedded in the three mounting slots 101. Each sensor module is interference-fitted with the mounting slot 101 on the side wall of the LVAD inflow tract main body 100 to reduce the risk of module loosening and fiber breakage caused by myocardial pulsation, pump vibration, or tissue micro-displacement during long-term implantation. The electrical connection wires in each sensor module are led out from the bottom of the module and arranged along the wiring cavity formed between the inner and outer walls of the left ventricular assist device inflow channel body 100. Finally, together with the electrical connection wires of the left ventricular assist device pump body, they are led out of the body through the subcutaneous channel and connected to the signal processing unit 500 located outside the body.

[0026] Furthermore, the fiber optic sensing probes of each sensor module are implanted into the myocardial tissue to form a deep in-situ detection area for the myocardium. In this embodiment, during the operation, before the left ventricular assist device inflow tract body 100 is inserted into the left ventricle, the fiber optic sensing probes of the reference fiber optic module 200, SPR lactate detection module 300, and NAD(P)H detection module 400 are implanted into the myocardial tissue tangentially or approximately tangentially along the ventricular wall via peel-away catheters; the fiber optic sensing probes are embedded for a predetermined length in the myocardial tissue along the tangential direction of the ventricular wall to form a stable deep in-situ detection area for the myocardium.

[0027] like Figure 2 As shown, the reference fiber module 200 includes a broadband micro LED light source 201, a reference fiber transmitting fiber 202, a black PEEK light blocking plate 203, a reference fiber collecting fiber 204, a photodiode 205, and a medical polyurethane encapsulation 206.

[0028] After the top of the wide-spectrum micro LED light source 201 is encapsulated and opened, it is fixed to the reference optical fiber emitting fiber 202 with optical adhesive; the black PEEK light blocking plate 203 separates the reference optical fiber emitting area and the reference optical fiber collecting area; in the light collecting area, the reference optical fiber collecting fiber 204 and the low-noise photodiode 205 are also fixed with optical adhesive after drilling.

[0029] After being encapsulated in medical polyurethane 206 and cast, the reference fiber optic module 200 is installed in the reference fiber optic module mounting slot on the side wall of the left ventricular assist device inflow tract body 100.

[0030] like Figure 3 As shown, the SPR lactic acid detection module 300 realizes lactic acid detection based on the surface plasmon resonance principle, including a broadband micro LED light source 301 with a center wavelength of 730nm and covering the preset SPR resonance wavelength offset range, an SPR coating lactic acid detection emitting fiber 302, a black PEEK light blocking plate 303, an SPR coating lactic acid detection collecting fiber 304, and a spectral resolution photoelectric conversion unit 305.

[0031] A broadband miniature LED light source 301 is fixedly connected to an SPR-coated lactic acid detection emitting fiber 302; a black PEEK light-blocking plate 303 is disposed between the emitting area and the collecting area to reduce stray light interference caused by the emitted light directly entering the collecting light path without passing through the SPR lactic acid sensing area.

[0032] The SPR-coated lactate detection transmitting fiber 302 and the SPR-coated lactate detection collecting fiber 304 form a continuous SPR lactate detection optical path within the myocardial tissue. The preset area of ​​the detection optical path is provided with an SPR metal coating and a lactate-sensitive layer. After lactate enters the lactate-sensitive layer, it undergoes an enzymatic reaction, which changes the local chemical environment, swelling state, and effective refractive index of the lactate-sensitive layer, thereby causing a shift in the SPR resonance wavelength.

[0033] In the optical signal collection area, the SPR-coated lactic acid detection and collection fiber 304 is optically connected to the spectral-resolved photoelectric conversion unit 305. The spectral-resolved photoelectric conversion unit 305 includes a miniature beam splitter and a high-sensitivity photodetector array. The miniature beam splitter is used to spatially separate the optical signals of different wavelengths output from the SPR-coated lactic acid detection and collection fiber 304. The high-sensitivity photodetector array is used to convert the optical signals of different wavelengths into corresponding electrical signals to obtain the SPR transmission spectrum and determine the SPR resonance wavelength.

[0034] The miniature beam splitter, the high-sensitivity photodetector array, and the SPR-coated lactic acid detection and collection fiber 304 are fixedly connected by optical adhesive after the encapsulation is opened.

[0035] The SPR lactate detection module 300 is cast using medical polyurethane encapsulation material and integrated into the lactate detection module mounting slot 101 on the side wall of the left ventricular assist device inflow tract main body 100.

[0036] like Figure 4 As shown, the NAD(P)H detection module 400 realizes NAD(P)H detection based on the fluorescence principle, including a 350nm wavelength miniature LED light source 401, an NAD(P)H emitting fiber 402, a black PEEK light-blocking plate 403, an NAD(P)H excitation light collecting fiber 404, a 400nm filter 405, and a high-sensitivity photodiode 406. The excitation wavelength of the miniature LED light source 401 is located in the range of 340–380nm, and excitation light within this wavelength range can excite NAD(P)H to produce fluorescence; in this embodiment, the wavelength of the miniature LED light source 401 is 350nm.

[0037] After the micro LED light source 401 is encapsulated and opened at its top, it is fixedly connected to the NAD(P)H emitting fiber 402 by optical adhesive; the black PEEK light-blocking plate 403 is disposed between the emitting area and the collecting area; in the light signal collecting path, the NAD(P)H excitation light collecting fiber 404, the 400nm filter 405 and the high-sensitivity photodiode 406 are fixedly connected by optical adhesive after the encapsulation opening.

[0038] The NAD(P)H detection module 400 is formed by casting with medical polyurethane encapsulation 407 and installed in the NAD(P)H detection module mounting slot 101 on the side wall of the left ventricular assist device inflow tract body 100.

[0039] Example 2 This embodiment provides a method for detecting myocardial metabolites in a left ventricular assist device, which is executed by the signal processing unit of the aforementioned system, such as... Figure 5 As shown, the method includes the following steps: S1: Acquire the reference optical path signal, lactate channel signal, and NAD(P)H channel signal; S2: Based on the cardiac component in the reference optical path signal, determine the low-motion diastolic moment of each heartbeat and form a detection window; S3: Extract the main detection amounts of lactate channels and NAD(P)H channels within the detection window; S4: Mechanical compensation is performed on the main detection quantities of the two channels using the ultra-high frequency interference component of the reference optical path signal; S5: Convert the compensated optical quantity of lactate channel into lactate concentration, and convert the compensated optical quantity of NAD(P)H channel into NAD(P)H relative metabolic index output.

[0040] The following detailed explanation will illustrate the implementation process of the above steps.

[0041] For step S1, the three signals are acquired by the reference fiber optic module 200, the SPR lactic acid detection module 300, and the NAD(P)H detection module 400, respectively. To suppress interference from ambient light and light source fluctuations, the signals of each channel undergo differential processing between light-on and light-off states within the corresponding light source time slot.

[0042] In this embodiment, the reference optical path signal is obtained according to the following formula: , (Equation 1); in, The reference effective voltage is the sampling time r within the time slot of the c-th channel light source; , These represent the average values ​​of the lights being on and off at sampling time r, respectively.

[0043] The lactic acid channel signal is the light-on and light-off differential signal of each pixel in the photosensitive array.

[0044] The NAD(P)H channel signal is the lamp-on / lamp-off differential signal of the fluorescence collection fiber: (Equation 2); in, The fluorescence collection differential signal is obtained at sampling time r; This is the voltage amplification factor.

[0045] Furthermore, the reference optical path signal is preprocessed to separate the slowly changing component, cardiac component, and ultra-high frequency interference signal, providing a benchmark for subsequent gating and compensation. In this embodiment, a baseline is established when the light source, optical path, and patient status are stable after implantation: Z (Equation 3); (Equation 4); in, This serves as the baseline for the reference optical path of channel c. This is the baseline initial sampling time; This represents the number of baseline sampling points; For reference optical path fluctuation amplitude; To prevent division by zero by a preset small amount.

[0046] (Equation 5); (Equation 6) (Equation 7); (Equation 8); in, It is a low-speed low-pass filter. The slowly changing component of the reference optical path; It is a high-speed low-pass filter. To preserve cardiac and slow changes, and to remove signals after removing ultra-high frequency changes caused by left ventricular assist device pump vibration and blood flow; The weight of heartbeat; It is an ultra-high frequency interference signal.

[0047] Regarding step S2 above, the individualized delay for each patient is determined using physiological signals recorded synchronously during the operation, and the moment of lowest myocardial motion in the mid-to-late diastolic phase of each heartbeat is predicted online. In this embodiment, at least one of electrocardiogram, cardiac catheterization, or ultrasound is recorded synchronously during the operation: (Equation 9); (Equation 10); in, Individualized delay for patients to reach the target low-motor moment based on reference characteristics; The target low-motion moment for the kth heartbeat in the calibration phase; This is the time when the reference feature of the k-th heartbeat appears during the calibration phase; The diastolic low-motor moment of the k-th heartbeat predicted online; The reference feature time for the k-th heartbeat identified online; median indicates taking the median.

[0048] (Equation 11); (Equation 12); in, The detection center time of the k-th heartbeat in channel c; The offset is determined based on the light source, detector, and readout delay of the c-th channel; This is the detection window for the k-th heartbeat in channel c; , These represent the window durations before and after the detection center's time, respectively. The detection window allows for a complete light-on-light-off differential sampling.

[0049] (Equation 13); in, The cardiac component of the kth heartbeat Compared with the patient's own cardiac template The correlation coefficient; corr represents the correlation operation; when the correlation coefficient meets the preset conditions, the corresponding detection window gate is determined to pass.

[0050] Optionally, the lactate channel and the NAD(P)H channel are acquired in a time-division manner within the same gated detection window; when the detection window is insufficient to accommodate the complete light source switching cycle of the two channels, the lactate channel and the NAD(P)H channel are acquired alternately in the adjacent gated heartbeats, ensuring the uniformity of the time reference of the detection data of the two channels.

[0051] For step S3 above, for the lactic acid channel, difference averaging and reference normalization are performed on each pixel of the photosensitive array within the effective gate window to obtain the corrected array spectrum: (Equation 14); (Equation 15); (Equation 16); in, This refers to the m-th pixel in the photosensitive array. For detection window The number of sampling points within; For pixels Average of the difference between light on and light off inside the door-controlled window; The average effective voltage of lactate reference within the same window; This is the array spectrum after pixel correction and normalization.

[0052] The minimum spectral point is searched within the preset SPR search band, and the sub-pixel resonance position is obtained by fitting a local quadratic curve, thereby determining the SPR resonance wavelength shift: (Equation 17); (Equation 18); (Equation 19); (Equation 20); (Equation 21); in, Preset SPR search band; The integer pixel number with the lowest spectral value within the search band; This represents the fitted spectral value of the k-th heartbeat at pixel position p; , , These are the coefficients for fitting the quadratic curve; The subpixel resonance position is denoted by g; g is the preset pixel-wavelength calibration function. It is the SPR resonance wavelength; The reference resonant wavelength; This is the main detection quantity for the lactate channel.

[0053] For the NAD(P)H channel, the fluorescence collection signal was normalized using a time-matched reference optical path signal, and a patient-specific baseline was established: (Equation 22); (Equation 23); (Equation 24); (Equation 25); (Equation 26); in, For detection window The number of sampling points within; The effective fluorescence signal of the k-th heartbeat; The average effective voltage of the NAD(P)H reference optical path in the same gate control window; This is the normalized fluorescence ratio; This serves as an individualized baseline for patients during the stable phase following implantation. The baseline starting heartbeat number; Baseline heart rate; This is the main detection quantity for the NAD(P)H channel.

[0054] For step S4 above, the main detection quantities of the two channels are uniformly entered into the compensation process: (Equation 27); Calculate a reference fast disturbance that is strictly time-matched to the gated detection, and perform compensation when the disturbance amplitude is within the calibration coverage range: (Equation 28); (Equation 29); (Equation 30); in, The delay between the ultra-high frequency interference waveforms of the reference optical path and the detection optical path (its calibration is shown in Example 3); The average value of the reference rapid perturbation is matched with the time of the kth heartbeat detection window; This represents the number of sampling points within the window. The root mean square magnitude of the fast disturbance referenced for the current window; Let c be the fixed mechanical compensation coefficient for the c-th channel; when When within the α calibration coverage area, mechanical compensation shall be performed according to (Equation 30); This is the main detection quantity after mechanical compensation.

[0055] Optionally, for slow drift caused by biofouling on the fiber surface, aging of the sensitive layer, light source attenuation, and long-term response changes of optoelectronic devices, slow drift compensation is performed after mechanical compensation: (Equation 31); in, The main detection quantity after slow drift compensation; The slow drift compensation coefficient for channel c is obtained from long-term animal experiments. This is the slowly changing component of the reference optical path.

[0056] For step S5, the compensated optical quantity of the lactate channel is converted into lactate concentration, and the compensated optical quantity of the NAD(P)H channel is converted into the NAD(P)H relative metabolic index output, which is calculated using the following formula: (Equation 32); (Equation 33); (Equation 34); in, This is a function for converting lactic acid concentration. This is a patient-specific relative index mapping function, used only for patient-specific baseline normalization and dimensional unification, and does not perform NAD(P)H absolute concentration conversion; This refers to the concentration of lactic acid. The relative metabolic index of NAD(P)H; For unified output; To ensure a unified timestamp, the two channels share the cardiac template, heartbeat number, and unified timestamp, but their respective reference time slot baseline, detection baseline, α, and β are independent.

[0057] Example 3 This embodiment provides calibration examples for α calibration and microdialysis calibration, wherein: α-calibration: During independent mechanical calibration or controlled calibration when the actual physiological quantities of the channel are relatively stable, the rapid residuals of the main detection quantity sequences are extracted to determine the delay between them and the ultra-high frequency interference waveform of the reference optical path. Candidate compensation coefficients are calculated using least squares within the calibration window, and the median is taken. (Equation 35); (Equation 36); (Equation 37); (Equation 38); (Equation 39); (Formula 40); (Equation 41); (Equation 42); in, This represents the original signal of channel c at sampling time r during the mechanical calibration phase. For fast residuals; To delay the search range; Let w be the set of sampling times for the w-th calibration window; This represents the number of sampling points within the window. , These are the reference UHF interference sequence and the fast residual sequence after removing the window mean, respectively. Candidate compensation coefficients; The regularization coefficient is used. This is a set of calibration windows that meet quality standards. The fixed mechanical compensation coefficients for the lactate channel and the NAD(P)H channel are calibrated independently and are not shared.

[0058] Microdialysis calibration: lactate channel conversion function Preferably, the method involves pairing microdialysis samples from the target myocardial region during surgery with optically measured lactate levels within the same time interval; the NAD(P)H channel is not calibrated for absolute concentration using microdialysis fluid. The microdialysis probe is positioned in a myocardial region adjacent to or having a pre-defined spatial correspondence with the lactate SPR detection area to collect lactate from the myocardial interstitial fluid.

[0059] Record the microdialysis tubing delay and the effective response delay of the analyte to determine the corresponding in situ myocardial time interval for the sample. In this embodiment: (Equation 43); (Equation 44); in, This represents the total delay of the microdialysis sample relative to the actual exposure time of the target myocardium; This refers to the dead volume retained within the microdialysis tubing. This refers to the microdialysis perfusion rate; This is due to the delay in lactic acid transmembrane exchange and analytical response; , These are the start and end times of the collection of the j-th sample, respectively; Let be the target myocardial time interval corresponding to the j-th sample.

[0060] Determine the relative recovery rate of microdialysis and calculate the reference concentration of myocardial interstitial tissue: (Equation 45); (Equation 46); When the perfusion fluid does not contain lactic acid, equation (46) simplifies to: (Equation 47); in, The lactic acid concentration of the j-th microdialysis solution was determined by an independent analytical method. The concentration of lactic acid in the perfusion fluid entering the microdialysis probe; The target myocardial interstitial lactate reference concentration to be estimated; This refers to the relative recovery rate of lactate under specific probe, membrane area, perfusion rate, temperature, and tissue conditions. The relative recovery rate of lactate is independently calibrated for specific microdialysis membranes, perfusion rates, sampling temperatures, sample processing procedures, and analytical methods, and can be determined through net-flux-free, reverse dialysis, low-flow-rate methods, or other validated methods.

[0061] Determine the calibration reference value based on the degree of recovery rate validation: (Equation 48); in, As an indicator of the effectiveness of recovery rate; This indicates that the sample used a myocardial interstitial reference concentration corrected for effective recovery rate; This indicates that only the dialysate concentration measured in the laboratory will be used for relative or semi-quantitative calibration within the patient. If the relative recovery rate has not been effectively validated, the concentration measured in the microdialysis fluid will only be used for relative or semi-quantitative calibration within the patient and will not be converted to an absolute myocardial interstitial concentration. Microdialysis samples with concentrations below the lower limit of quantitation, insufficient sample volume, blood contamination, incomplete sampling time records, abnormal recovery rates, or unsatisfactory sample stability should be excluded from the calibration set.

[0062] Establish an effective set of optical detection points and count their number: (Equation 49); (Formula 50); (Equation 51); in, This is the timestamp of the k-th optical detection point; This is the result of the k-th diastolic gating; the value is 1 if the gating passes, and 0 otherwise. This represents the quality judgment result of the kth detection point in the cth channel. If the quality is qualified, it is set to 1; otherwise, it is set to 0. It is the set of effective optical detection points; For timestamps located at The set of all candidate optical points; the vertical line symbol indicates the number of elements in the set. Optical points that do not meet the quality requirements are directly excluded, and no continuous quality weight is assigned.

[0063] When the sampling time intervals are basically consistent, or when the changes in heart rate and data update intervals do not exceed a preset range, the arithmetic mean of the effective optical detection points is calculated to form a calibration data pair: (Equation 52); (Equation 53); in, The average optical quantity of the j-th microdialysis sample within the corresponding time interval; An individualized lactate calibration point was established for each patient. Within the preset calibration range, the relationship between the lactate photoelectric signal and the myocardial interstitial lactate concentration corrected for microdialysis recovery was considered linear. A conversion function from the optically detected lactate quantity to the myocardial interstitial lactate concentration was established based on each calibration point. .

[0064] For the NAD(P)H channel, an individualized baseline should be established for the patient within a preset time period after implantation when the light source, optical path, and patient hemodynamic status are stable. After completing diastolic gating, α mechanical compensation, β slow drift compensation, and quality checks As a relative metabolic index of NAD(P)H for the patient. In the absence of validated myocardial tissue reference measurements, It is only used to characterize the trend of change relative to the individual patient's baseline and the dynamic response before and after LVAD adjustment, and is not converted to absolute NAD(P)H concentrations such as μmol / L or μmol / g. Optionally, if myocardial tissue samples are obtained during the operation due to the implantation of a left ventricular assist device, and the samples are subjected to rapid metabolic quenching and independent NADPH / NADP+ measurement, the tissue measurement results can be used as a one-time in-patient reference point for the correction or verification of the relative index, but do not replace continuous relative index output.

[0065] Example 4 This embodiment provides an experimental example: to verify the feasibility of the detection scheme, a single experimental pig was used for implantation testing. During the experiment, reference concentrations were obtained through microdialysis sampling and cardiac puncture, and compared with the sensor calculation values ​​to verify the continuous response capability of the lactate detection channel and the NAD(P)H detection channel to changes in myocardial metabolism and their consistency with the reference detection results. The experimental results are as follows: Figures 6 to 11 As shown, where, Figure 6 This is the quantitative comparison result of lactate channels. Figure 8 The alignment results are for the NAD(P)H channel. Figure 7 and Figure 9 Continuous signal recordings for lactate channels and NAD(P)H channels, respectively. Figure 10 and Figure 11 The scatter plot shows the correlation analysis results of 10 paired samples.

[0066] like Figure 6 As shown, the horizontal axis represents time, and the vertical axis represents lactate concentration. The solid line represents the reference concentration measured by microdialysis and puncture sampling, and the dashed line represents the concentration calculated by the sensor. Throughout the monitoring process, the trends of the sensor-calculated concentration and the reference concentration were consistent. The lactate concentration first experienced an upward phase and then entered a downward phase. The sensor-calculated concentration tracked both the upward and downward phases, and the correlation coefficient between the two was r=0.87.

[0067] like Figure 7 The image shows the continuous raw signal and 60-second window mean of the lactate channel during the same monitoring process. The continuous raw signal exhibits fluctuations caused by myocardial pulsation and pump operation. After window averaging and signal processing, the window mean curve becomes stable and consistent with... Figure 6 The rising and falling segments correspond to the concentration of lactic acid in the middle.

[0068] like Figure 8As shown, the horizontal axis represents time, and the vertical axis represents NAD(P)H concentration. The solid line represents the reference concentration, and the dashed line represents the concentration calculated by the sensor. The NAD(P)H concentration first decreased and then increased during the monitoring process. The sensor-calculated concentration tracked this change, and the correlation coefficient between the two was r=0.83.

[0069] It should be noted that the reference value of the NAD(P)H channel in this experimental example was obtained by rapid metabolic quenching and independent NAD(P)H measurement of myocardial tissue samples obtained by cardiac puncture; the sensor calculation value of the NAD(P)H channel in the figure was obtained by converting the tissue measurement result as a one-time in-patient reference point, and was only used to verify the consistency between the response of the NAD(P)H detection channel to changes in myocardial metabolism and the reference detection result, and was not used as the continuously output absolute concentration of NAD(P)H; the continuous output of the NAD(P)H channel in this embodiment is still the relative metabolic index of NAD(P)H relative to the patient's individualized baseline.

[0070] like Figure 9 As shown, this represents the continuous raw signal of the NAD(P)H channel and the 60-second window mean during the same monitoring process. The window mean curve is compared with... Figure 8 The decrease and increase of NAD(P)H concentration correspond to the same period.

[0071] like Figure 10 and Figure 11 In the scatter plot, the horizontal axis represents the reference concentration and the vertical axis represents the sensor-calculated concentration. The data points are distributed near the diagonal, further indicating that there is a correlation between the sensor-calculated values ​​and the reference concentration in both channels.

[0072] Experimental results show that the correlation coefficient r between the lactate channel sensor calculated value and the reference lactate concentration is 0.87; the correlation coefficient r between the NAD(P)H channel sensor calculated value and the reference NAD(P)H concentration is 0.83. The experimental data did not undergo slow drift compensation coefficient β correction. Continuous signals and calculation results may still be affected by factors such as biofouling on the fiber optic surface, aging of the sensitive layer, light source attenuation, and long-term response changes of optoelectronic devices. The current results demonstrate the preliminary feasibility of the detection scheme. A universal β value needs to be determined through fitting and verification in animal experiments with larger sample sizes, different implantation durations, and different experimental conditions.

[0073] Example 5 This embodiment also provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments. In this embodiment, the electronic device is a controller housing a signal processing unit located externally, and is connected to each sensor module via electrical connection lines led out through a subcutaneous channel.

[0074] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A myocardial metabolite detection system for a left ventricular assist device, characterized in that, include: Left ventricular assist device inflow tract main body (100); A reference fiber optic module (200), a lactate detection module (300), and an NAD(P)H detection module (400) are integrated into the side wall of the inflow tract body (100) of the left ventricular assist device. The fiber optic sensing probes of the reference fiber optic module (200), the lactate detection module (300), and the NAD(P)H detection module (400) are respectively implanted in myocardial tissue. The signal processing unit (500) is electrically connected to the reference fiber module (200), the lactate detection module (300), and the NAD(P)H detection module (400); The detection optical path of the lactate detection module (300) is provided with an SPR metal coating and a lactate sensitive layer in a preset area; the NAD(P)H detection module (400) is used to emit excitation light to myocardial tissue and collect the fluorescence generated by NAD(P)H in myocardial tissue when excited. The signal processing unit (500) is configured to: Based on the cardiac component in the reference optical path signal of the reference fiber module (200), the diastolic low motion moment of each heartbeat is determined and a detection window is formed; The main detection quantities of lactate channel and NAD(P)H channel are extracted within the detection window. The main detection quantity of lactate channel is determined based on SPR resonance wavelength shift, and the main detection quantity of NAD(P)H channel is determined based on normalized fluorescence signal. Mechanical compensation is performed on the main detection quantities of the lactic acid channel and the main detection quantities of the NAD(P)H channel using the ultra-high frequency interference component of the reference optical path signal; The optical quantities of mechanically compensated lactate channels were converted into lactate concentration, and the optical quantities of mechanically compensated NAD(P)H channels were converted into NAD(P)H relative metabolic index output.

2. The myocardial metabolite detection system for a left ventricular assist device according to claim 1, characterized in that, The reference fiber optic module (200), the lactate detection module (300), and the NAD(P)H detection module (400) are respectively integrally cast and encapsulated with medical polyurethane material and are correspondingly embedded in the mounting groove (101) on the side wall of the left ventricular assist device inflow channel body (100); The electrical connection lines of each module are led out from the bottom of the module, arranged along the wiring cavity formed between the inner wall and the outer wall of the left ventricular assist device inflow channel body (100), and led out of the body through the subcutaneous channel together with the electrical connection lines of the left ventricular assist device pump body; The signal processing unit (500) is disposed outside the body and connected to the electrical connection line extending outside the body.

3. The myocardial metabolite detection system for a left ventricular assist device according to claim 1, characterized in that, The fiber optic sensing probe extends outward from the side wall of the inflow tract body (100) of the left ventricular assist device and is embedded in the myocardial tissue tangentially or approximately tangentially along the ventricular wall.

4. The myocardial metabolite detection system for a left ventricular assist device according to claim 1, characterized in that, The reference fiber module (200) includes a wide-spectrum micro LED light source (201), a reference fiber emitting fiber (202), a black PEEK light-blocking plate (203), a reference fiber collecting fiber (204), and a photodiode (205). The black PEEK light-blocking plate (203) is disposed between the emitting area and the collecting area. The lactic acid detection module (300) includes a broadband micro LED light source (301) with a center wavelength of 730nm, an SPR-coated lactic acid detection emitting fiber (302), a black PEEK light-blocking plate (303), an SPR-coated lactic acid detection collecting fiber (304), and a spectral resolution photoelectric conversion unit (305). The spectral resolution photoelectric conversion unit (305) includes a micro beam splitter and a high-sensitivity photodetector array. The micro beam splitter is used to spatially separate the light signals of different wavelengths output by the SPR-coated lactic acid detection collecting fiber (304), and the high-sensitivity photodetector array is used to convert the light signals of different wavelengths into electrical signals respectively to obtain the SPR transmission spectrum. The NAD(P)H detection module (400) includes a 350nm wavelength micro LED light source (401), an NAD(P)H emitting fiber (402), a black PEEK light-blocking plate (403), an NAD(P)H excitation light collecting fiber (404), a 400nm filter (405), and a high-sensitivity photodiode (406). The 400nm filter (405) is disposed between the NAD(P)H excitation light collecting fiber (404) and the high-sensitivity photodiode (406).

5. A method for detecting myocardial metabolites in a left ventricular assist device, characterized in that, include: The reference optical path signal, lactate channel signal, and NAD(P)H channel signal are acquired. The lactate channel signal is acquired by a lactate detection module with an SPR metal coating and a lactate sensitive layer in a preset area of ​​the detection optical path. The NAD(P)H channel signal is acquired based on the fluorescence generated by NAD(P)H in myocardial tissue upon excitation. Based on the cardiac component in the reference optical path signal, the low-motion diastolic moment of each heartbeat is determined, and a detection window is formed; The main detection quantities of lactate channel and NAD(P)H channel are extracted within the detection window. The main detection quantity of lactate channel is determined based on SPR resonance wavelength shift, and the main detection quantity of NAD(P)H channel is determined based on normalized fluorescence signal. Mechanical compensation is performed on the main detection quantities of the lactic acid channel and the main detection quantities of the NAD(P)H channel using the ultra-high frequency interference component of the reference optical path signal; The optical quantities of mechanically compensated lactate channels were converted into lactate concentration, and the optical quantities of mechanically compensated NAD(P)H channels were converted into NAD(P)H relative metabolic index output.

6. The method for detecting myocardial metabolites in a left ventricular assist device according to claim 5, characterized in that, Acquiring the reference optical path signal, the lactic acid channel signal, and the NAD(P)H channel signal includes: performing differential processing on the signal within the time slot of each channel light source by subtracting the average value from the average value when the light is on; The primary detection quantity of the NAD(P)H channel is determined based on the normalized fluorescence signal, including: calculating the normalized ratio of the fluorescence signal and the reference optical path signal within the same detection window; establishing a patient-specific baseline of the normalized ratio during a stable patient condition phase; and using the change in the normalized ratio relative to the patient-specific baseline as the primary detection quantity of the NAD(P)H channel.

7. The method for detecting myocardial metabolites in a left ventricular assist device according to claim 5, characterized in that, It also includes: slow drift compensation for the main detection quantities after mechanical compensation, wherein the slow drift compensation is performed according to the following formula: ； In the above formula, This is the primary detection quantity for the k-th heartbeat in channel c after slow drift compensation. This is the primary detection quantity for the k-th heartbeat in the c-th channel after mechanical compensation. This is the preset slow drift coefficient for channel c. For the k-th heartbeat, the slowly changing component of the reference optical path within the detection window. .

8. The method for detecting myocardial metabolites in a left ventricular assist device according to claim 5, characterized in that, The determination of the diastolic low-motion moment of each heartbeat based on the cardiac component in the reference optical path signal includes: Simultaneous recording of at least one of electrocardiogram, cardiac catheterization, and ultrasound during the procedure to determine the patient-specific delay from reference characteristics to the target low-motion moment; The reference features of the k-th heartbeat are identified online, and the diastolic low-motor moment of the k-th heartbeat is predicted based on the occurrence time of the reference features and the individualized delay of the patient. Calculate the correlation between the cardiac component of the current heartbeat and the preset cardiac template. When the correlation meets the preset conditions, determine that the corresponding detection window gate passes. The lactate channel and the NAD(P)H channel are acquired in a time-sharing manner within the same gated detection window; when the detection window is insufficient to accommodate the complete light source switching cycle of the two channels, the lactate channel and the NAD(P)H channel are acquired alternately in adjacent gated heartbeats.

9. The method for detecting myocardial metabolites in a left ventricular assist device according to claim 5, characterized in that, The main detectable quantity of the lactate channel is determined based on the SPR resonance wavelength shift, including: The signals of each pixel in the photosensitive array within the detection window are averaged and normalized to obtain the corrected array spectrum; Within a preset SPR search band, determine the integer pixel with the lowest spectral value in the array spectrum; A local quadratic curve fitting is performed in the vicinity of the integer pixel, and the fitting formula is: ； Calculate the sub-pixel resonance position based on the fitted quadratic curve: ； in, Let be the fitted spectral value of the k-th heartbeat, and p be the pixel position. , , The coefficients are obtained from fitting the quadratic curve of the k-th heartbeat. This represents the subpixel resonance position of the k-th heartbeat; The subpixel resonance position is converted into the SPR resonance wavelength according to the preset pixel-wavelength calibration function, and the offset of the SPR resonance wavelength relative to the reference resonance wavelength is calculated.

10. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the method for detecting myocardial metabolites in a left ventricular assist device according to any one of claims 5-9.

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