A mid-infrared femtosecond laser arteriosclerosis ablation transmission system and an ablation method

Abstract

The application belongs to the technical field of medical devices, and particularly relates to a kind of middle infrared femtosecond laser arteriosclerosis ablation transmission system and ablation method, including pump light source, first dielectric film mirror, second dielectric film mirror, light beam through spatial light isolator, middle infrared generation module, first ZnSe lens, first gold-coated film mirror, second gold-coated film mirror, second ZnSe lens, ablation transmission system arranged on signal light path in turn.The application can effectively solve the technical bottleneck that middle infrared femtosecond laser has high transmission loss in traditional optical fiber and cannot maintain pulse time-frequency domain characteristics, realize low-loss, shape-preserving transmission, endow laser beam with good flexibility and controllability, meet the clinical needs of intravascular intervention treatment, and can also realize instant suction and removal of stripped plaque during ablation process, effectively block the risk of embolism complication caused by fragments drifting to distal vessels with blood flow.

Description

Technical Field

[0001] This invention relates to a mid-infrared femtosecond laser ablation transmission system and ablation method for arteriosclerosis, belonging to the field of medical device technology. Background Technology

[0002] In recent years, laser ablation for arteriosclerosis has become a hot topic in clinical treatment due to its advantages such as being minimally invasive, precise, and repeatable. Compared with traditional radiofrequency or microwave ablation, laser ablation energy deposition is more localized; especially with the introduction of femtosecond-level ultrashort pulses, tissue ablation can be completed before heat dissipates, thereby minimizing the extent of thermal damage. Furthermore, by matching the laser wavelength to the mid-infrared band (2.5–12 μm), strong resonance can occur with the vibrational absorption peaks of key groups such as ester bonds, proteins, and hydroxyapatite in arteriosclerotic tissue, achieving efficient and highly selective absorption, thereby improving ablation precision and minimizing damage to adjacent healthy tissues.

[0003] Currently, the commonly used mid-infrared solid optical fibers (such as those based on chalcogenide glass, fluoride or silver halide materials) have a certain light transmission range in specific wavelength bands. However, due to the high intrinsic absorption of the materials in the mid-infrared region, coupled with the limitations on the usable length and bending degree of the optical fibers, they often exhibit high transmission loss, as well as significant pulse broadening and spectral distortion in practical applications.

[0004] In addition, although the distal embolization protection devices currently used in clinical practice are widely adopted, they still have a series of significant defects in terms of effectiveness, operation design and long-term prognosis in actual application. Most of the existing devices are "additional components" that are independent of the treatment device, and this split design brings a series of problems in operation. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a mid-infrared femtosecond laser ablation transmission system and ablation method for arteriosclerosis. On one hand, this invention effectively solves the technical bottlenecks of high transmission loss and spectral distortion in traditional optical fibers by introducing a chalcogenide anti-resonant hollow optical fiber with special design parameters as the transmission medium. This achieves low-loss, conformal transmission while endowing the laser beam with good flexibility and controllability, meeting the clinical needs of endovascular interventional therapy. On the other hand, this invention integrates the external sheath of the optical fiber with the ablation fragment recovery function, combining it with the laser transmission channel. This enables simultaneous and immediate aspiration and removal of the ablated plaque during the ablation process, effectively preventing the risk of fragments drifting with the blood flow to distal blood vessels and causing embolic complications.

[0006] The technical solution provided by this invention to solve the above-mentioned technical problems is: a mid-infrared femtosecond laser ablation transmission system for arteriosclerosis, comprising, in sequence, a pump source, a first dielectric film reflector, a second dielectric film reflector, a beam isolator, a mid-infrared generation module, a first ZnSe lens, a first gold-plated film reflector, a second gold-plated film reflector, a second ZnSe lens, and an ablation transmission system. The pump source outputs a femtosecond laser, which is collimated by passing through a first dielectric film reflector and a second dielectric film reflector. The collimated beam is then transmitted to the mid-infrared generation module via a spatial optical isolator. The mid-infrared generation module employs a two-stage optical parametric amplification system, utilizing nonlinear optical frequency conversion technology to efficiently convert the femtosecond laser into mid-infrared femtosecond lasers of 5.75 μm and 9.5 μm. The mid-infrared femtosecond laser is first collimated by a first ZnSe lens, and the collimated mid-infrared beam undergoes optical path direction adjustment by passing through a first gold-plated film reflector and a second gold-plated film reflector. The second ZnSe lens then couples the mid-infrared femtosecond laser into the ablation transmission system. The ablation transmission system efficiently transmits the mid-infrared femtosecond laser generated by the mid-infrared generation module to the target ablation area.

[0007] A further technical solution is that the surfaces of both the first dielectric film reflector and the second dielectric film reflector are coated with a 1030nm high-reflectivity film.

[0008] A further technical solution is that the mid-infrared generation module includes a first-stage optical parametric amplification system and a second-stage optical parametric amplification system; the first-stage optical parametric amplification system includes a half-wave plate, a thin-film polarizer, a reflector, a first-stage dichroic mirror, an LGS crystal, a long-pass filter, a first reflector, and a second reflector arranged sequentially along the signal optical path input direction; the LGS crystal has a size of 4mm × 4mm × 8mm, and the crystal's incident and exit surfaces are coated with anti-reflection films in the 1030nm and 1.1μm to 1.3μm bands, respectively, and its crystal cutting angle is 50.4 degrees; The second-stage optical parametric amplification system includes a third reflecting mirror, a fourth reflecting mirror, a second-stage dichroic mirror, a BGS crystal, and germanium arranged sequentially along the input direction of the signal optical path; the BGS crystal has a size of 5mm × 5mm × 10mm, and the incident and exit surfaces of the crystal are coated with dual-band antireflection films of 1.1μm to 1.3μm and 9μm to 11μm, respectively, with a cutting angle of 74.9 degrees.

[0009] A further technical solution is that the pump light power density of the second-stage optical parametric amplification system is preferably 15 GW / cm². 2 Up to 20 GW / cm 2 .

[0010] A further technical solution is that both the first ZnSe lens and the second ZnSe lens are coated with an anti-reflection film of 4μm to 12μm, with the preferred focal length range of the first ZnSe lens being 50mm to 100mm and the preferred focal length range of the second ZnSe lens being 25mm to 75mm.

[0011] A further technical solution is that the ablation transmission system includes an integrated sleeve and an electric three-axis displacement stage. The integrated sleeve is placed on the electric three-axis displacement stage, which is equipped with an X-axis drive motor, a Y-axis drive motor, and a Z-axis drive motor.

[0012] A further technical solution is that the integrated cannula includes a tube wall and an anti-resonant hollow optical fiber disposed within the tube wall for transmitting mid-infrared femtosecond laser, a fragment blocking device for intercepting tissue fragments during ablation, an aspiration device for rinsing the ablation area or aspirating residues and liquids, and an empty imaging catheter channel.

[0013] A further technical solution is that the anti-resonant hollow optical fiber is composed of an air core and multiple anti-resonant capillaries surrounding the core.

[0014] A mid-infrared femtosecond laser ablation method for arteriosclerosis specifically includes the following steps: Step 1: Position the upper end of the integrated cannula directly over the target tissue area; Step 2: The femtosecond laser output from the pump source is then collimated by passing it sequentially through the first dielectric film mirror and the second dielectric film mirror. Step 3: The collimated beam is transmitted to the mid-infrared generation module via a spatial optical isolator. The mid-infrared generation module adopts a two-stage optical parametric amplification system and uses nonlinear optical frequency conversion technology to efficiently convert the femtosecond laser into mid-infrared femtosecond lasers of 5.75 and 9.5 μm. Step 4: The mid-infrared femtosecond laser is first collimated by the first ZnSe lens, and the collimated mid-infrared beam is then adjusted in optical path direction by the first gold-plated reflector and the second gold-plated reflector. Step 5: The mid-infrared femtosecond laser is then coupled into the integrated sleeve of the ablation transmission system by the second ZnSe lens; Step 6: The integrated sleeve efficiently transmits the mid-infrared femtosecond laser generated by the mid-infrared generation module to the target ablation area for ablation.

[0015] A further technical solution is that the specific ablation process in step six is ​​as follows: First, the coordinated movement of the X-axis drive motor, Y-axis drive motor, and Z-axis drive motor compensates for optical path deviations caused by environmental disturbances in real time, ensuring that the mid-infrared laser maintains optimal coupling efficiency during the coupling process into the anti-resonant hollow optical fiber; simultaneously, when the 5.75 μm and 9.5 μm mid-infrared femtosecond lasers ablate the target ablation area, the suction device and the fragment blocking device work together; the fragment blocking device deploys first to intercept tissue fragments with a diameter greater than 100 μm; the suction device starts synchronously, continuously suctioning the tiny particles and rinsing fluid in the ablation area; after ablation is completed, the suction device switches to enhanced suction mode to concentrate and remove the fragments intercepted on the surface of the fragment blocking device.

[0016] The present invention has the following beneficial effects: 1. This invention is the first to utilize specific wavelengths of 5.75 and 9.5 μm to achieve highly efficient selective ablation of atherosclerotic plaques of different severities (5.75 μm wavelength for atherosclerotic plaques; 9.5 μm wavelength for calcified plaques).

[0017] 2. This invention, by combining anti-resonant hollow fiber light guiding technology, enables laser power to be transmitted smoothly and directly reach lesion areas that are difficult for conventional instruments to access. This characteristic helps to remove deep plaques more effectively, making it closer to the actual needs of clinical operation. In addition, the temporal and spectral characteristics of the femtosecond laser remain almost completely unchanged after transmission through the anti-resonant hollow fiber, which has a good effect on maintaining the stability of laser parameters.

[0018] 3. This invention uses lasers to ablate arteriosclerosis without damaging the normal blood vessels beneath it, preserving healthy tissue to the greatest extent possible and achieving a minimally invasive effect.

[0019] 4. The device described in this invention is designed with integration and portability in mind. Guided by optical fiber, it offers greater operational flexibility. Furthermore, the debris-blocking net, transmission fiber, aspiration device, and imaging catheter channel are all integrated into a single tubing. This reduces the complexity of the surgery, makes the operation relatively controllable, ensures good safety, and minimizes side effects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the integrated sleeve structure; Figure 3 Fourier transform infrared spectrum of atherosclerotic plaques in human arteries; Figure 4 This is a scanning electron microscope image of the anti-resonant hollow optical fiber used in this invention. Figure 5An ablation slice of atherosclerotic plaque in human arteries; Figure 6 This is an image showing the ablation effect on a normal pig artery. Detailed Implementation

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

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1 As shown, a mid-infrared femtosecond laser ablation transmission system for arteriosclerosis according to the present invention includes a pump light source 1, a first dielectric film reflector 2, a second dielectric film reflector 3, a beam passing through a spatial optical isolator 4, a mid-infrared generation module 5, a first ZnSe lens 6, a first gold-plated film reflector 7, a second gold-plated film reflector 8, a second ZnSe lens 9, and an ablation transmission system, which are sequentially arranged in the signal optical path. The system's workflow involves a femtosecond laser (with a center wavelength of 1030 nm, a pulse width of 250 fs, and a repetition rate of 500 kHz) output from a pump source 1, which is characterized by high peak power and narrow pulse width, providing an ideal pump source for subsequent nonlinear frequency conversion. The output beam is collimated sequentially through a first dielectric film reflector 2 and a second dielectric film reflector 3. The collimated beam is then transmitted to a mid-infrared generation module 5 via a spatial optical isolator 4. This module employs a two-stage optical parametric amplification system, utilizing nonlinear optical frequency conversion technology to efficiently convert the femtosecond laser into a 9.5 μm mid-infrared femtosecond laser. The mid-infrared femtosecond laser is first collimated by a first ZnSe lens 6, and then its optical path is adjusted by a first gold-plated film reflector 7 and a second gold-plated film reflector 8. Finally, a second ZnSe lens 9 couples the mid-infrared femtosecond laser into the ablation transmission system. The ablation transmission system efficiently transmits the mid-infrared femtosecond laser generated by the mid-infrared generation module 5 to the target ablation area.

[0026] In this embodiment, the surfaces of the first dielectric film reflector 2 and the second dielectric film reflector 3 are both coated with a 1030nm high-reflectivity film with a reflectivity greater than 99.5%, which can effectively reduce power loss during transmission.

[0027] In this embodiment, the spatial light isolator 4 is used to prevent reflected light from returning to the pump light source and causing damage; its operating wavelength is 1030nm, the isolation degree is greater than 30 dB, and the transmittance is greater than 90%, which can effectively block the back-transmitted reflected light and ensure the stable operation of the pump light source.

[0028] In this embodiment, the mid-infrared generation module 5 includes a first-stage optical parametric amplification system and a second-stage optical parametric amplification system; In this embodiment, the first-stage optical parametric amplification system serves as a pre-amplification stage, used to generate and amplify the signal light corresponding to the infrared wavelength in the target. Specifically, it includes a half-wave plate, a thin-film polarizer, a reflector, a first-stage dichroic mirror, an LGS crystal, a long-pass filter, a first reflector, and a second reflector arranged sequentially along the input direction of the signal light path. The LGS crystal has dimensions of 4mm × 4mm × 8mm, and its incident and exit surfaces are coated with anti-reflection films for the 1030nm and 1.1μm to 1.3μm wavelength bands, respectively. Its crystal cutting angle is 50.4 degrees. The second-stage optical parametric amplification system serves as the main amplification stage, used to further amplify the signal light and generate mid-infrared idler light from the target. Specifically, it includes a third reflecting mirror, a fourth reflecting mirror, a second-stage dichroic mirror, a BGS crystal, and germanium arranged sequentially along the input direction of the signal light path. The BGS crystal has dimensions of 5mm × 5mm × 10mm, and its incident and exit surfaces are coated with dual-band antireflection films of 1.1μm to 1.3μm and 9μm to 11μm, respectively, with a cutting angle of 74.9 degrees.

[0029] The pump power density of the second-stage optical parametric amplifier system is preferably between 15 GW / cm² and 20 GW / cm². By adjusting the pump power density and the crystal temperature, fine control of the output mid-infrared laser power and spectral bandwidth can be achieved. The crystal temperature is controlled within the range of 25°C to 50°C, with a temperature control accuracy better than ±0.1°C, in order to maintain the stability of the phase matching conditions.

[0030] Through the design of the above two-stage optical parametric amplification system and the optimization and control of key parameters, this invention achieves efficient and stable output of 9.5μm wavelength mid-infrared femtosecond laser, providing a reliable light source guarantee for the subsequent selective ablation of atherosclerotic plaques.

[0031] In this embodiment, both the first ZnSe lens 6 and the second ZnSe lens 9 are coated with an anti-reflection film of 4μm to 12μm. The preferred focal length range of the first ZnSe lens 6 is 50mm to 100mm, and the preferred focal length range of the second ZnSe lens 9 is 25mm to 75mm. These focal lengths can be selected according to the interface size and coupling requirements of the integrated sleeve 12. The coupling efficiency is optimized by adjusting the position of the integrated sleeve and the beam direction, and the final coupling efficiency can reach more than 85%. The surface coating has an average transmittance of more than 97% in the 4μm to 12μm band, which can effectively reduce reflection loss.

[0032] like Figure 2 As shown, in this embodiment, the ablation transmission system includes an integrated sleeve 12, an electric triaxial displacement stage 13, and a coupling feedback device. The integrated sleeve 12 is placed on the electric triaxial displacement stage 13, and the electric triaxial displacement stage 13 is equipped with an X-axis drive motor 14, a Y-axis drive motor 15, and a Z-axis drive motor 16. The coupling feedback device includes a first photodetector 10, a first photodetector rail 11, a second photodetector 17, a second photodetector rail 18, and a computer 19; the first photodetector 10 and the second photodetector 17 are both controlled by the computer 19. The first photodetector 10 and the second photodetector 17 are slidably mounted on the first photodetector rail 11 and the second photodetector rail 18, respectively, and the first photodetector 10 and the second photodetector 17 measure the input and output power of the optical fiber, respectively. The coupling feedback device characterizes the coupling efficiency by real-time detection of the ratio of the fiber output power to the incident spatial light reference power, thereby stabilizing the coupling efficiency above a preset threshold. Specifically, as shown in the figure, before the spatial light enters the hollow fiber, a movable first photodetector 10 moves into the optical path to obtain a reference signal for the input optical power. After obtaining the optical power value, it moves away to restore the optical path. During testing at the output end of the hollow fiber, a movable second photodetector 17 is connected to the optical path to obtain the fiber output power signal. After the power test is completed, it moves out to restore the optical path.

[0033] The controller calculates the ratio of the output power to the reference power in real time to obtain the current coupling efficiency, and compares it with a preset efficiency value (e.g., 70%).

[0034] When the controller detects that the ratio has dropped below the threshold, it immediately generates a three-dimensional position adjustment command, driving the X, Y, and Z axis motors to perform optimization motion at the fiber input end in a plane perpendicular to the optical axis, searching for and locking the position where the coupling efficiency is restored to its maximum value. This feedback adjustment process continues, effectively compensating for alignment offsets caused by environmental vibrations and other factors, ensuring that the coupling efficiency is always not lower than the preset value, and achieving highly stable coupling of spatial light to hollow optical fiber. The integrated sleeve 12 outputs from the output port 20.

[0035] In this embodiment, the integrated sleeve 12 is output from the ablation transmission system via the output port 20, and its cross-section is as follows: Figure 2 As shown, it includes a tube wall 25 and an anti-resonant hollow optical fiber 21 disposed within the tube wall 25 for transmitting mid-infrared femtosecond laser, a fragment blocking device 22 for intercepting tissue fragments during ablation, an aspiration device 23 for rinsing the ablation area or aspirating residues and liquids, and an empty imaging catheter channel 24.

[0036] The anti-resonant hollow fiber 21 is made of chalcogenide glass material. Based on the anti-resonant light guiding mechanism, it has excellent optical transmission performance in the mid-infrared band and can efficiently transmit mid-infrared femtosecond laser with a wavelength of 9.5μm. It has the advantages of low transmission loss, high damage threshold and controllable dispersion, which meet the clinical application needs of ablation of atherosclerotic plaques.

[0037] The waveguide structure of its anti-resonant hollow optical fiber 21 consists of an air core and multiple anti-resonant capillaries surrounding the core. The capillary wall thickness is optimized according to the anti-resonance condition, so that light within a specific wavelength range is confined to the air core for transmission. The chalcogenide glass is preferably composed of As₂S₃ or As₂Se₃. This type of material has a low absorption coefficient in the mid-infrared 5μm to 10μm band, and the theoretical transmission loss can be controlled within the range of 0.05dB / m to 0.2dB / m, compared to the 10μm range of traditional silica optical fiber in the mid-infrared band. 4 dB / m to 106 The transmission loss of dB / m is a significant advantage. The inner diameter of the antiresonant hollow fiber is preferably 200μm to 300μm. This size ensures both high laser transmission efficiency and compatibility with the internal space of the integrated sleeve 12, enabling compact integration of multiple channels. The outer diameter of the fiber is preferably 400μm to 800μm, and the outer surface is coated with a polyimide or acrylate protective layer with a thickness of 20μm to 50μm to enhance the fiber's mechanical strength and bending resistance.

[0038] After being coupled into the anti-resonant hollow fiber 21 via the second ZnSe lens 9, the laser beam is transmitted in a low-loss manner within the air core to the target ablation region. To ensure coupling efficiency, the numerical aperture of the anti-resonant hollow fiber 21 is preferably between 0.1 and 0.2, matching the focusing spot size of the second ZnSe lens 9. The coupling efficiency can be maintained at the set value in real time by three-way drive motors, ensuring that the laser power transmitted to the target tissue meets the ablation requirements.

[0039] The bending radius of the anti-resonant hollow optical fiber 21 is designed to be no less than 30 mm. Thanks to the wide-band low-loss transmission characteristics of the anti-resonant structure, it can still maintain extremely low bending loss under moderate bending conditions during vascular intervention, avoiding the decrease in transmission efficiency or damage to the optical fiber caused by bending.

[0040] During laser ablation, the mid-infrared femtosecond laser transmitted through the anti-resonant hollow fiber 21 is output to the surface of the atherosclerotic plaque. The laser parameters match the characteristic absorption peaks of the plaque, achieving efficient and selective ablation. The chalcogenide material of the anti-resonant hollow fiber 21 has a high laser damage threshold and can withstand peak power densities of several GW / cm². 2 The device transmits femtosecond laser pulses without causing damage, while the anti-resonant structure confines most of the optical power within the air core, effectively avoiding material nonlinear effects and heat accumulation, thus ensuring the long-term reliability of the device. Furthermore, the flexibility of the anti-resonant hollow fiber is compatible with the overall flexible design of the integrated sleeve, enabling stable transmission even in the tortuous paths of blood vessels.

[0041] By combining the aforementioned antiresonant hollow optical fiber with a mid-infrared femtosecond laser source, this invention achieves efficient and selective ablation of atherosclerotic plaques. The excellent mid-infrared transmission performance of the chalcogenide antiresonant hollow optical fiber, its reasonable structural parameter design, and its synergistic operation with other functional modules of the integrated sleeve jointly ensure the accuracy, safety, and reliability of the laser ablation device.

[0042] Its fragment blocking device 22 is used to intercept detached atherosclerotic plaque fragments and tissue debris during laser ablation, preventing them from migrating with the blood flow to distal blood vessels and causing embolic complications.

[0043] The fragment blocking device 22 employs a precision-woven nickel-titanium alloy basket structure. This basket consists of 3 to 6 elastic support wires and a microporous mesh film covering the support wires. Nickel-titanium alloy possesses excellent superelasticity and shape memory effect, allowing it to automatically unfold at body temperature while exhibiting excellent biocompatibility. In its folded state, the basket is housed within the channel of the integrated cannula's fragment blocking device 22. Its outer diameter is no larger than the outer diameter of the integrated cannula, facilitating its delivery to the target location via blood vessel. Once the integrated cannula reaches the targeted ablation area, the basket is pushed out of the channel opening by pushing a control guidewire positioned proximal to the catheter. After being pushed out, the basket automatically unfolds into an umbrella or basket-like structure due to its own elasticity, tightly adhering to the inner wall of the blood vessel.

[0044] The unfolding diameter of the basket can be selected according to the inner diameter of the target blood vessel, preferably in the range of 2mm to 6mm, to accommodate the size of arteries in different locations.

[0045] The mesh size design of the microporous membrane needs to balance debris interception efficiency and blood perfusion requirements. The preferred mesh diameter is 100 μm. This size range can effectively intercept tissue debris with a diameter greater than 100 μm, while tiny particles with a diameter less than 100 μm can pass through with the blood flow, avoiding complete blockage of distal blood supply.

[0046] The elastic support wire has a diameter of 0.1 mm to 0.2 mm and its surface is treated with a hydrophilic coating to reduce frictional damage to the blood vessel wall.

[0047] During laser ablation, the fragment blocking device 22 deploys before laser output to ensure that fragments generated during ablation are intercepted the moment they detach. After ablation, the suction device 23 removes the fragments intercepted on the surface of the basket, achieving efficient fragment recovery. Once suction is complete, the guide wire is retracted, and the basket retracts and returns to its original position inside the integrated sleeve under the pull-back force, allowing the entire device to be removed from the body.

[0048] The aspiration device 23 employs a dual-chamber design, forming a flushing channel and an aspiration channel. These two channels are axially parallel within the integrated sheath and communicate with the outside via a common end face opening at their distal ends. This dual-chamber structure ensures that the flushing fluid and aspiration paths are independent, preventing cross-contamination between the flushing fluid and the aspirated material. Furthermore, the flushing flow rate and aspiration negative pressure can be independently controlled according to the actual needs of the ablation process. The proximal end of the flushing channel connects to an external flushing fluid source, and the proximal end of the aspiration channel connects to an external negative pressure suction system. The inner diameter of the flushing channel is preferably 0.3 mm to 0.5 mm, and the inner diameter of the aspiration channel is preferably 0.4 mm to 0.6 mm. The cross-sectional area design of the two channels must balance fluid dynamics performance with the overall outer diameter limitation of the integrated sheath 12, ensuring efficient fluid delivery within a limited space. The flushing fluid is physiological saline or heparinized physiological saline, with a flow rate controlled within the range of 0.5 mL / min to 2.0 mL / min. This effectively flushes away tiny debris and air bubbles generated in the ablation area without causing impact damage to the vessel wall due to excessive flow rate. The negative pressure of the aspiration channel is controlled within the range of 50 mmHg to 200 mmHg, and the aspiration flow rate is 1.0 mL / min to 3.0 mL / min. This parameter range can effectively remove suspended fragments with a diameter of less than 300 μm, while avoiding excessive negative pressure that could cause collapse or damage to the blood vessel wall.

[0049] During laser ablation, the aspiration device 23 and the fragment blocking device 22 work in concert. The fragment blocking device 22 deploys first to intercept tissue fragments larger than 100 μm in diameter; the aspiration device 23 starts simultaneously, continuously aspirating the tiny particles and irrigation fluid within the ablation area. After ablation, the aspiration device 23 switches to enhanced aspiration mode, concentrating and removing the fragments intercepted on the surface of the fragment blocking device 22. In enhanced aspiration mode, the aspiration negative pressure can be adjusted from 150 mmHg to 300 mmHg, and the aspiration duration is from 10 s to 30 s, ensuring effective removal of fragments. During aspiration, the irrigation channel is simultaneously replenished with irrigation fluid to maintain local fluid balance and prevent a sudden drop in intravascular pressure due to excessive aspiration. The distal end face opening of the aspiration device 23 adopts a concentric ring structure design, which is conducive to forming a uniform aspiration flow field and reducing the impact of local turbulence on the vessel wall. The inner wall of the aspiration device 23 is treated with a hydrophilic lubricating coating to reduce fragment adhesion and improve aspiration efficiency.

[0050] Through the synergistic effect of the fragment blocking device 22 and the suction device 23, the present invention achieves a dual protection mechanism of "intercepting first and then suctioning" ablation fragments, effectively reducing the risk of distal vascular embolism and improving the safety of laser ablation treatment for arteriosclerosis.

[0051] The empty imaging catheter channel 24 is an empty channel that can accommodate the catheter tip of an imaging device, such as an OCT or ultrasound imaging device, as needed, so that it can directly reach the lesion area; thereby, in the process of laser ablation, information on the intravascular tissue structure can be obtained in real time to achieve precise positioning of atherosclerotic plaques, dynamic monitoring of the ablation process, and immediate evaluation of the ablation effect.

[0052] The present invention provides a mid-infrared femtosecond laser ablation method for arteriosclerosis, which specifically includes the following steps: Step 1: Position the upper end of the integrated sleeve 12 directly over the target tissue area; Step 2: The femtosecond laser output from pump source 1 is then collimated by passing through the first dielectric film reflector 2 and the second dielectric film reflector 3 in sequence. Step 3: The collimated beam is transmitted to the mid-infrared generation module 5 via the spatial optical isolator 4. The mid-infrared generation module 5 adopts a two-stage optical parametric amplification system and uses nonlinear optical frequency conversion technology to efficiently convert the femtosecond laser into a 9.5 μm mid-infrared femtosecond laser. Step 4: The mid-infrared femtosecond laser is first collimated by the first ZnSe lens 6, and the collimated mid-infrared beam is then adjusted in optical path direction by the first gold-plated reflector 7 and the second gold-plated reflector 8. Step 5: The mid-infrared femtosecond laser is then coupled into the integrated sleeve 12 of the ablation transmission system by the second ZnSe lens 9; Step 6: The integrated sleeve 12 efficiently transmits the mid-infrared femtosecond laser generated by the mid-infrared generation module 5 to the target ablation area for ablation; The specific ablation process is as follows: First, the coordinated movement of the X-axis drive motor 14, Y-axis drive motor 15, and Z-axis drive motor 16 compensates for optical path deviations caused by environmental disturbances in real time, ensuring that the mid-infrared laser maintains optimal coupling efficiency during coupling into the anti-resonant hollow fiber. Simultaneously, when the 9.5 μm mid-infrared femtosecond laser ablates the target ablation area, the suction device 23 and the fragment blocking device 22 work together. The fragment blocking device 23 deploys first to intercept tissue fragments with a diameter greater than 100 μm. The suction device 23 starts synchronously and continuously suctions the tiny particles and rinsing fluid in the ablation area. After ablation is completed, the suction device 25 switches to enhanced suction mode to concentrate and remove the fragments intercepted on the surface of the fragment blocking device 22.

[0053] Figure 3This is a Fourier transform infrared spectrum of atherosclerotic plaques in human arterial tissue. The image clearly shows strong absorption peaks near 5.75 μm and 9.5 μm, corresponding to the characteristic absorption of cholesterol esters and hydroxyapatite in the plaque, respectively. This invention selects these two wavelengths as ablation wavelengths because they exhibit significant specific absorption differences compared to normal tissue: normal tissue shows weaker absorption at 5.75 μm and 9.5 μm. Therefore, using these wavelengths for laser ablation can achieve selective removal of atherosclerotic plaques, reducing the risk of damage to surrounding normal tissues.

[0054] Figure 4 This is a scanning electron microscope (SEM) image of the antiresonant hollow optical fiber used in this invention. As shown, the antiresonant hollow optical fiber is composed of chalcogenide glass, preferably As₂S₃ or As₂Se₃. This type of material exhibits low intrinsic absorption and a high nonlinear threshold in the long-wavelength mid-infrared band, making it suitable for high-power femtosecond laser transmission. The fiber structure employs an antiresonant hollow waveguide design, with an air core surrounded by multiple antiresonant capillaries. The capillary wall thickness is optimized based on antiresonance conditions, allowing light in the 5 μm to 12 μm wavelength range to be efficiently confined within the air core for transmission. The fiber's inner diameter is preferably 200 μm to 500 μm, its outer diameter is preferably 400 μm to 800 μm, its capillary wall thickness is preferably 0.8 μm to 1.5 μm, and the number of capillaries is preferably 6 to 8. This combination of structural parameters achieves a transmission loss of less than 0.1 dB / m, with measured transmission losses of less than 0.08 dB / m and 0.12 dB / m at wavelengths of 5.75 μm and 9.5 μm, respectively. The outer surface of the fiber is coated with a polyimide or acrylate protective layer with a thickness of 20 μm to 50 μm to enhance the fiber's mechanical strength and bending resistance. This antiresonant hollow fiber exhibits a bending-induced loss of less than 0.2 dB with a bending radius of not less than 30 mm, meeting the flexible manipulation requirements of vascular interventional procedures and providing a crucial guarantee for the efficient and low-distortion transmission of mid-infrared femtosecond lasers.

[0055] Figure 5 This is an ablation section of an atherosclerotic plaque in a human body. Experimental results show that the total cross-sectional area before ablation was 9.54 mm². 2 The ablation area decreased to 3.15 mm within 3 minutes. 2 It can achieve a volume reduction rate of 33%, demonstrating a highly efficient and effective ablation effect.

[0056] Figure 6This image shows the ablation effect on a normal porcine artery. Under the same laser parameters, with an ablation time four times longer than that for atherosclerotic plaques, the ablation cross-sectional area of ​​a normal porcine artery was only 0.15 mm². Calculations show that this ablation rate is approximately 80 times different from that of atherosclerotic plaques, fully demonstrating that the mid-infrared femtosecond laser used in this invention has high selectivity for atherosclerotic plaques, effectively removing diseased tissue while maximizing the protection of surrounding normal tissue.

[0057] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A mid-infrared femtosecond laser ablation transmission system for arteriosclerosis, characterized in that, The system includes, in sequence, a pump light source (1), a first dielectric film reflector (2), a second dielectric film reflector (3), a beam passing through a spatial optical isolator (4), a mid-infrared generation module (5), a first ZnSe lens (6), a first gold-plated film reflector (7), a second gold-plated film reflector (8), a second ZnSe lens (9), and an ablation transmission system. The pump source (1) outputs a femtosecond laser. The femtosecond laser passes through the first dielectric film reflector (2) and the second dielectric film reflector (3) in sequence to collimate the output optical path. The collimated beam is transmitted to the mid-infrared generation module (5) through the spatial optical isolator (4). The mid-infrared generation module (5) adopts a two-stage optical parametric amplification system and uses nonlinear optical frequency conversion technology to efficiently convert the femtosecond laser to mid-infrared femtosecond lasers of 5.75 and 9.5 μm. The mid-infrared femtosecond laser is first collimated by the first ZnSe lens (6). The collimated mid-infrared beam is then adjusted in optical path direction by the first gold-plated film reflector (7) and the second gold-plated film reflector (8). The mid-infrared femtosecond laser is then coupled into the ablation transmission system by the second ZnSe lens (9). The ablation transmission system (10) efficiently transmits the mid-infrared femtosecond laser generated by the mid-infrared generation module (5) to the target ablation area.

2. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 1, characterized in that, The surfaces of the first dielectric film reflector (2) and the second dielectric film reflector (3) are both coated with a 1030nm high-reflection film.

3. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 1, characterized in that, The mid-infrared generation module (5) includes a first-stage optical parametric amplification system and a second-stage optical parametric amplification system. The first-stage optical parametric amplification system includes a half-wave plate, a thin-film polarizer, a reflector, a first-stage dichroic mirror, an LGS crystal, a long-pass filter, a first reflector, and a second reflector arranged sequentially along the signal light path input direction. The LGS crystal has a size of 4mm × 4mm × 8mm, and the crystal's incident and exit surfaces are coated with anti-reflection films in the 1030nm and 1.1μm to 1.3μm bands, respectively. Its crystal cutting angle is 50.4 degrees. The second-stage optical parametric amplification system includes a third reflecting mirror, a fourth reflecting mirror, a second-stage dichroic mirror, a BGS crystal, and germanium arranged sequentially along the input direction of the signal optical path; the BGS crystal has a size of 5mm × 5mm × 10mm, and the incident and exit surfaces of the crystal are coated with dual-band antireflection films of 1.1μm to 1.3μm and 9μm to 11μm, respectively, with a cutting angle of 74.9 degrees.

4. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 3, characterized in that, The preferred pump power density for the second-stage optical parametric amplifier system is 15 GW / cm². 2 Up to 20GW / cm 2 .

5. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 1, characterized in that, Both the first ZnSe lens (6) and the second ZnSe lens (9) are coated with an anti-reflection film of 4μm to 12μm. The preferred focal length range of the first ZnSe lens (6) is 50mm to 100mm, and the preferred focal length range of the second ZnSe lens (9) is 25mm to 75mm.

6. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 1, characterized in that, The ablation transmission system includes an integrated sleeve (12) and an electric three-axis displacement stage (13). The integrated sleeve (12) is placed on the electric three-axis displacement stage (13), which is equipped with an X-axis drive motor (14), a Y-axis drive motor (15), and a Z-axis drive motor (16).

7. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 6, characterized in that, The integrated cannula (12) includes a tube wall (25) and an anti-resonant hollow optical fiber (21) for transmitting mid-infrared femtosecond laser, disposed in the tube wall (25), a fragment blocking device (22) for intercepting tissue fragments during ablation, a suction device (23) for rinsing the ablation area or aspirating residues and liquids, and an empty imaging catheter channel (24).

8. The mid-infrared femtosecond laser arteriosclerosis ablation transmission system according to claim 7, characterized in that, The anti-resonant hollow optical fiber (21) consists of an air core and multiple anti-resonant capillaries surrounding the core.

9. A mid-infrared femtosecond laser ablation method for arteriosclerosis, characterized in that, This method uses a mid-infrared femtosecond laser arteriosclerosis ablation transmission system as described in any one of claims 1-8 to perform arteriosclerosis ablation, specifically including the following steps: Step 1: Position the upper end of the integrated sleeve (12) directly over the target tissue area; Step 2: The femtosecond laser output from the pump source (1) is then collimated by passing through the first dielectric film mirror (2) and the second dielectric film mirror (3) in sequence. Step 3: The collimated beam is transmitted to the mid-infrared generation module (5) via the spatial optical isolator (4). The mid-infrared generation module (5) adopts a two-stage optical parametric amplification system and uses nonlinear optical frequency conversion technology to efficiently convert the femtosecond laser into mid-infrared femtosecond lasers of 5.75 and 9.5 μm. Step 4: The mid-infrared femtosecond laser is first collimated by the first ZnSe lens (6), and the collimated mid-infrared beam is then adjusted in optical path direction by the first gold-plated film reflector (7) and the second gold-plated film reflector (8). Step 5: The mid-infrared femtosecond laser is then coupled into the integrated sleeve (12) of the ablation transmission system by the second ZnSe lens (9); Step 6: The integrated sleeve (12) efficiently transmits the mid-infrared femtosecond laser generated by the mid-infrared generation module (5) to the target ablation area for ablation.

10. The method for mid-infrared femtosecond laser ablation of arteriosclerosis according to claim 9, characterized in that, The specific ablation process in step six is ​​as follows: First, the coordinated movement of the X-axis drive motor (14), Y-axis drive motor (15), and Z-axis drive motor (16) compensates for the optical path deviation caused by environmental disturbances in real time, ensuring that the mid-infrared laser maintains the optimal coupling efficiency during the coupling process into the anti-resonant hollow fiber; at the same time, when the 5.75 and 9.5 μm mid-infrared femtosecond lasers ablate the target ablation area, the suction device (23) and the debris blocking device (22) work together. The fragment blocking device (23) is deployed first to intercept tissue fragments with a diameter greater than 100μm; the suction device (23) is started simultaneously to continuously suction the tiny particles and rinsing fluid in the ablation area; after ablation is completed, the suction device (25) switches to enhanced suction mode to concentrate and suction the fragments intercepted on the surface of the fragment blocking device (22) to remove them.

Images