Catheter that combines optical tissue assessment and laser ablation

Abstract

The present invention describes an apparatus and method for performing combined optical tissue assessment and laser ablation using a catheter system. The catheter system includes a processing device and a catheter, the catheter having a proximal section and a distal section, the distal section having a plurality of optical ports. The plurality of optical ports are configured to emit an exposure radiation beam to a sample, receive one or more scattered radiation beams, and emit laser ablation energy so that a portion of the sample is ablated. The processing device includes a first light source configured to generate an exposure radiation source beam; and a second light source configured to generate laser ablation energy. The catheter system also includes one or more multiplexers that direct the exposure radiation beam to the plurality of optical ports, combine the one or more scattered radiation beams, and direct the laser ablation energy to at least one of the plurality of optical ports.

Description

Technical Field

[0001] Embodiments of the present invention relate to the design and methods of use of catheters that incorporate optical tissue assessment and laser ablation. Background Art

[0002] Ablation is a medical technique used to produce tissue necrosis. It is used to help treat different pathologies, including cancer, Barrett's esophagus, or heart arrhythmias. In some cases, various types of ablation may be used, such as cryogenic cooling for cryoablation, chemicals for chemical ablation, radiofrequency (RF) ablation, laser ablation, etc. For radiofrequency (RF) ablation, an alternating current with an oscillation frequency higher than several hundred kilohertz (kHz) is applied to avoid irritating the tissue while transferring heat by the Joule effect.

[0003] The increase in tissue temperature produces denaturation of biomolecules, including proteins such as collagen, myosin or elastin. Traditionally, radiofrequency ablation is performed by placing external electrodes on the patient's body, and applying alternating current to the tip of a catheter placed in the patient's body and in contact with the tissue to be treated. The ablation effect depends on a variety of factors, including the applied electrical power, the quality of the electrical contacts, local tissue properties, the presence of blood flow close to the tissue surface, and the effectiveness of irrigation. Due to the variability of these parameters, it is difficult to obtain consistent results. Summary of the invention

[0004] Existing ablation catheters and methods for radiofrequency ablation therapy are limited because it is challenging to align the catheter electrodes to the target tissue to meet the accuracy during the radiofrequency ablation procedure. In the embodiments presented herein, an ablation catheter is described that combines optical tissue assessment and laser ablation.

[0005] The ablation catheter can provide a cost-effective solution to radiofrequency ablation catheters, where each electrode in the radiofrequency ablation catheter uses complex electrical wires. In some embodiments, the ablation catheter includes multiple optical ports for evaluating and ablating target tissue. By allowing laser ablation energy to be transmitted through the same optical port used for tissue evaluation, the ablation catheter can use a single substrate that allows focal evaluation of the target tissue being ablated. In the embodiments presented herein, an apparatus and method for performing optical tissue evaluation and laser ablation using a catheter having multiple optical ports is described, which are used to transmit exposure radiation beams and laser ablation energy to the target tissue.

[0006] In one embodiment, a catheter system includes a catheter and a treatment device. The catheter has a distal section, a proximal section, and a sheath coupled between the distal section and the proximal section. The distal section includes a plurality of optical ports and a holder that holds the plurality of optical ports in a fixed spatial relationship. The plurality of optical ports are configured to emit one or more exposure radiation beams to a sample, receive one or more scattered radiation beams that have been reflected or scattered from the sample, and emit laser ablation energy so that at least a portion of the sample is ablated. The proximal section of the treatment device or catheter includes: a first light source configured to generate an exposure radiation source beam; and a second light source configured to generate laser ablation energy. The catheter system also includes a multiplexer configured to direct one or more exposure radiation beams from a radiation source beam to the plurality of optical ports, combine one or more scattered radiation beams, and direct laser ablation energy to at least one of the plurality of optical ports. An example method for performing combined optical tissue assessment and laser ablation is described in the embodiment. The method includes providing an ablation catheter, wherein the ablation catheter includes a proximal end, a distal end having a plurality of optical ports, and a sheath coupled between the proximal end and the distal end. The method also includes: emitting one or more exposure radiation beams to a sample near the distal end of the ablation catheter via the plurality of optical ports; receiving one or more radiation beams that have been scattered or reflected from the sample via the plurality of optical ports; and ablating at least a portion of the sample using laser ablation energy output from at least one of the plurality of optical ports.

[0007] In another embodiment, a catheter system for performing combined optical tissue assessment and laser ablation is described. The catheter system includes a catheter and a processing device, the catheter having a distal section, a proximal section, and a sheath coupled between the proximal section and the distal section. The distal section includes a plurality of optical ports configured to emit one or more exposure radiation beams to a sample, receive one or more scattered radiation beams that have been reflected or scattered from the sample, and emit laser ablation energy so that at least a portion of the sample is ablated. The proximal section of the processing device or catheter includes a first light source configured to generate an exposure radiation source beam, and a second light source configured to generate laser ablation energy. Further features and advantages, as well as the structure and operation of various embodiments are described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are not intended to be limiting. These embodiments are used herein for illustrative purposes only. Based on the teachings contained herein, other embodiments will be apparent to those skilled in the relevant art. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the invention and, together with the description, further serve to explain the principles of the invention and to enable one skilled in the relevant art to make and use the invention.

[0009] Figure 1 An example diagram of a catheter according to an embodiment of the present disclosure is shown.

[0010] Figure 2A and Figure 2B A cross-section of a catheter according to an embodiment of the present disclosure is shown.

[0011] Figures 3A to 3G Shown is a view of the distal end of a catheter in accordance with an embodiment of the present disclosure.

[0012] Figure 4A and Figure 4B Additional views of the distal end of a catheter are shown in accordance with an embodiment of the present disclosure.

[0013] Figure 5A and Figure 5B An example block diagram of a combined optical evaluation and laser ablation system for a catheter according to an embodiment of the present disclosure is shown.

[0014] Figure 6 Example graphs of blackbody spectra at different wavelengths and temperatures are shown.

[0015] Figure 7 An example diagram of a layer stack for a silicon nitride waveguide according to an embodiment of the present disclosure is shown.

[0016] Figure 8 An example diagram of an apparatus designed to direct a radiation beam according to an embodiment of the present disclosure is shown.

[0017] Fig. 9A and 9B Example graphs of reflectivity as a function of wavelength and layer thickness are shown, respectively, according to embodiments of the present disclosure.

[0018] Fig.10 An example environment of a waveguide with a flushing method according to an embodiment of the present disclosure is shown.

[0019] Fig.11 An example graph showing the focal plane position for each wavelength at a corresponding focal eigenvalue depth is shown in accordance with an embodiment of the present disclosure.

[0020] Fig.12 An example method for performing combined optical tissue assessment and laser ablation according to an embodiment of the present disclosure is shown.

[0021] Embodiments of the present invention will be described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] Although specific configurations and arrangements are discussed, it should be understood that this is for illustrative purposes only. Those skilled in the art will recognize that other configurations and arrangements may be used without departing from the spirit and scope of the present invention. Those skilled in the art will appreciate that the present invention may also be used in a variety of other applications.

[0023] It should be noted that references to "an embodiment", "an embodiment", "an example embodiment", etc. in the specification indicate that the described embodiment may include a particular feature, structure, or characteristic, but each embodiment may not necessarily include a particular feature, structure, or characteristic. Moreover, such expressions do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, whether or not it is explicitly described, those skilled in the art will implement such feature, structure, or characteristic within the scope of their knowledge.

[0024] As used herein, "laser energy" or "laser ablation energy" refers to light emitted by an optical amplification process based on stimulated emission of electromagnetic radiation, and refers to one or more laser beams generated by a laser source. It should be noted that although the present application may be specifically directed to cardiac ablation, the embodiments described herein may also be directed to other lesions with additional energy sources for ablation. The principles of using laser ablation energy to treat other lesions are similar, and therefore the techniques for applying laser ablation energy are similar.

[0025] Embodiments of an ablation catheter for combining optical tissue assessment and laser ablation are disclosed herein, wherein the ablation catheter includes multiple optical ports for assessing and ablating target tissue. In some embodiments, the multiple optical ports of the catheter are configured to transmit an exposure radiation beam to a sample, receive one or more scattered radiation beams that have been reflected or scattered from the sample, and emit laser energy to ablate at least a portion of the sample. By utilizing the same optical port to transmit an optical assessment signal and a laser ablation signal, the ablation catheter can provide focal assessment of the same target tissue being ablated in a single substrate that allows both modalities.

[0026] In this document, the terms "electromagnetic radiation", "light", and "radiation beam" are all used to describe the same electromagnetic signal that is propagated by the various components and systems described.

[0027] Catheter Embodiment

[0028] Figure 1A catheter 100 according to an embodiment of the present disclosure is shown. The catheter 100 includes a proximal section 102, a distal section 104, and a sheath 106 coupled between the proximal section 102 and the distal section 104. In an embodiment, the sheath 106 includes one or more radiopaque markers for navigation purposes. In one embodiment, the catheter 100 includes a communication interface 110 between the catheter 100 and a processing device 108. The communication interface 110 may include one or more wires between the processing device 108 and the catheter 100. In other examples, the communication interface 110 is an interface element that allows wireless communication, such as Bluetooth, WiFi, a cellular network, etc. The communication interface 110 can communicate with one or more transceiver elements located in the proximal section 102 or the distal section 104 of the catheter 100.

[0029] In one embodiment, the sheath 106 and the distal section 104 are disposable. In this way, each time a new procedure is to be performed, the proximal section 102 can be reused by attaching a new sheath 106 and distal section 104. In another embodiment, the proximal section 102 is also disposable.

[0030] In some embodiments, various electronic and optical components such as a power source, a first light source and a second light source, and an interferometer element are located in the processing device 108, and electrical and optical signals from these components can be sent to the proximal section 102 via the communication interface 110. By housing these components in the processing device 108, the entire catheter 100 can be disposable.

[0031] In other embodiments, the proximal section 102 can accommodate various electronic components and optical components used in the operation of the catheter 100. A first light source can be included in the proximal section 102 to generate a radiation source beam for optical evaluation. The first light source can include one or more laser diodes, super luminescent diodes (SLEDs) or light emitting diodes (LEDs). The radiation beam generated by the light source can have a wavelength in the infrared region. In one example, the radiation beam has a central wavelength of 1.3 μm. The light source can be designed to output a radiation beam only at a single wavelength, or it can be a swept source and designed to output a range of different wavelengths. The generated radiation beam can be guided to the distal section 104 via an optical transmission medium connected between the proximal section 102 and the distal section 104 in the sheath 106. Some examples of optical transmission media include single-mode, polarization-maintaining, or multimode optical fibers and integrated optical waveguides. In one embodiment, the electrical transmission medium and the optical transmission medium are provided by the same mixed medium that allows electrical and optical signals to propagate.

[0032] In addition, the proximal segment 102 may include a second light source, such as a laser energy source for tissue ablation. In some embodiments, the laser energy source may emit a laser energy ablation beam having a wavelength of 980 nm or a wavelength of 1060 nm. The laser energy from the source in the proximal segment 102 may propagate downward to the catheter 100 via an optical transmission medium connected within the sheath 106 between the proximal segment 102 and the distal segment 104, and the laser energy may be output from the distal segment 104 of the catheter 100 to the target tissue. For example, the laser energy from the source may generate 5W to 12W of optical power, which is applied to the target tissue for 20-30 seconds and may produce transmural damage in the cardiac tissue. In another example, the laser energy from the source may generate 30W to 50W of optical power, which is applied to the target tissue for 60-90 seconds. Refer to Figure 5A and Figure 5B , details about how a first light source for optical evaluation, and a second light source for laser ablation, are coupled together are discussed.

[0033] In one embodiment, the proximal section 102 includes one or more components of an interferometer to perform low coherence interferometry (LCI) using light generated from the first light source. Due to the nature of interferometric data analysis, in one embodiment, the optical transmission medium used to direct light to and from the distal end 104 does not affect the state and degree of polarization of the light. In another embodiment, the optical transmission medium affects the polarization in a constant and reversible manner.

[0034] The proximal section 102 may include additional interface elements whereby a user of the catheter 100 may control the operation of the catheter 100. For example, the proximal section 102 may include a deflection control mechanism that controls the deflection angle of the distal section 104. The deflection control mechanism may require mechanical movement of an element on the proximal section 102, or the deflection control mechanism may use an electrical connection to control the movement of the distal section 104. The proximal section 102 may include various buttons or switches that allow a user to apply laser energy at the distal end 104, or control when a radiation beam is emitted from the distal end 104, thereby allowing optical data to be acquired. In some examples, these buttons or switches are located at a separate user interface coupled to the processing device 108.

[0035] The distal segment 104 includes a plurality of optical observation ports, which will be described in further detail below. In one embodiment, one or more optical observation ports are machined into the outer body of the distal segment 104. For example, the one or more optical observation ports of the outer body of the distal segment 104 may be produced by laser drilling, 3D printing, stereolithography (SLA), fused deposition modeling (FDM), selective laser sintering (SLS), or other techniques. The optical observation ports are distributed on the outside of the distal segment 104, thereby producing a plurality of different observation directions. The optical observation ports also allow for a plurality of directions in which laser energy can be directed for tissue ablation through one or more optical observation ports. In one embodiment, each of the plurality of observation directions is substantially non-coplanar. The optical observation ports may also be designed with an irrigation function to cool the distal segment 104 and surrounding tissue during ablation. Reference Figures 3A to 3G and FIG. 4A to FIG. 4B , discussing design details regarding the distal section 104 .

[0036] Figure 2A and Figure 2B A cross-sectional view of a sheath 106 is shown according to an embodiment of the present disclosure. The sheath 106 may include all elements interconnecting the proximal section 102 and the distal section 104. The sheath 106a shows an embodiment housing an irrigation channel 202, a deflection mechanism 206, electrical connections 208, and an optical transmission medium 210. Figure 2A A protective cover 212 is shown wrapped over the electrical connections 208 and the optical transmission medium 210. The electrical connections 208 can be used to provide signals to the optical adjustment components located in the distal section 104. One or more optical transmission mediums 210 direct light generated from the light source (exposing light) toward the distal section 104, while another subset of optical transmission mediums 210 direct light returned from the distal section 104 (scattered or reflected light) back to the proximal section 102. In another example, the same one or more optical transmission mediums 210 direct light in both directions. In some embodiments, one or more optical transmission mediums 210 can also be used to propagate ablation laser energy (e.g., generated from a laser energy source) to the distal section 104 of the catheter 100.

[0037] The irrigation channel 202 is a hollow tube that can direct cooling fluid toward the distal segment 104. The irrigation channel 202 can include heating and / or cooling elements disposed along the channel to affect the temperature of the fluid. In another embodiment, the irrigation channel 202 can also be used as a way to direct fluid around the distal segment 104 back to the proximal segment 102.

[0038] The deflection mechanism 206 may include electrical or mechanical elements designed to provide a signal to the distal segment 104 in order to change the deflection angle of the distal segment 104. According to an embodiment, the deflection system is capable of guiding the distal segment 104 by actuating a mechanical control placed in the proximal segment 102. The system may be based on a series of aligned and evenly spaced cutouts in the sheath 106, which are intended to provide a unidirectional deflection of the distal segment 104, combined with a line connecting the deflection mechanism control in the proximal segment 102 to the catheter tip at the distal segment 104. In this way, a specific movement of the proximal segment can be projected to the distal segment. There are other embodiments involving a combination of several control lines attached to the catheter tip, which can enable the catheter tip to deflect in different directions.

[0039] Figure 2B A cross section of the sheath 106b is shown. The sheath 106b depicts a substantially similar Figure 2A The sheath 106b may be used in situations where conditioning (e.g., multiplexing) of the generated radiation beam is performed in the proximal section 102 or the processing device 108. In some embodiments, the sheath 106b may include electrical connections for electrodes in the distal section 104 for measuring an electrocardiogram of the tissue.

[0040] Figures 3A to 3G 1 shows a view within the distal section 104 according to an embodiment of the present disclosure. For example, Figure 3A A distal segment 104a is shown having a plurality of viewing ports 302, a plurality of waveguides 304, and one or more irrigation channels 310 located substantially at the tip of the distal segment 104a. The plurality of viewing ports 302 may be arranged in any pattern around the exterior of the distal segment 104a to enable various views of the sample 308. Laser energy may be directed to at least one of the plurality of viewing ports 302 to ablate a portion of the sample 308. In one embodiment, the waveguide 304 may be any type of waveguide structure, such as a waveguide defined within an optical integrated circuit. In another embodiment, the waveguide 304 may be a waveguide structure defined on a flexible substrate. In yet another embodiment, the waveguide 304 may be an optical fiber. A multiplexing unit 312 may also be defined on the same flexible substrate including the waveguide structure.

[0041] exist Figure 3A and Figure 3B, a waveguide 304 is used for each of the plurality of observation ports 302 to transmit and receive light through each of the plurality of observation ports 302. The exposed light exits the distal section 104a through the observation port 302 and is emitted onto the sample 308, while the light scattered or reflected by the sample 308 is received through the observation port 302. Each of the plurality of observation ports 302 may include more than one optical fiber, such as a fiber bundle. Light generated from a first light source within the proximal section 102 or the processing device 108 (e.g., for tissue assessment) may be separated in each of the observation ports 302 using a multiplexing unit 312. Alternatively, the multiplexing unit 312 may select one of the plurality of observation ports 302 for light to travel to or from.

[0042] Additionally, laser energy generated from a second light source (e.g., for laser ablation) within the proximal section 102 or the treatment device 108 can be directed to more than one viewing port 302 using the same multiplexing unit 312 or a different multiplexing unit (not shown) to select at least one of the multiple viewing ports 302 for target ablation. The multiplexing unit 312 receives the input beam of radiation and the laser beam via the light emission line 316. The light emission line 316 can include any number of light emitting elements (e.g., optical fibers) and can be similar to Figure 2A and Figure 2B The optical transmission medium 210 may include wires 318 to carry control signals from the proximal section 102 of the catheter 100 or from the processing device 108 to the multiplexing unit 312.

[0043] The multiplexing unit 312 may include associated electronics 314 that provide control signals to various conditioning elements of the multiplexing unit 312. The multiplexing unit 312 may use any multiplexing method that allows separation of light collected by multiple observation ports 302, and separation of light for optical tissue assessment and light for laser ablation. One such multiplexing method is time-domain multiplexing, in which the multiplexing unit 312 switches between different output waveguides in a controlled manner such that only one of the associated observation ports 302 is active at a given time. Another suitable multiplexing method is frequency-domain multiplexing, in which the light passing through each observation port 302 is conditioned such that the time-frequency behavior of the signals corresponding to the different observation ports 302 can be distinguished by a processing device (e.g., the processing device 108). Coherence-domain multiplexing may also be used with the multiplexing unit 312 by introducing different group delays into the light passing through each observation port 302 so that the signals corresponding to the different observation ports 302 appear at different coherence locations and can therefore be distinguished by a processing device (e.g., the processing device 108). In one embodiment, these methods are non-exclusive and can be combined to find the best design compromise. Some multiplexing methods, such as coherent domain multiplexing, do not require any electrical actuation of the multiplexing unit 312. Therefore, in one embodiment, based on the implementation of coherent domain multiplexing, no electrical transmission medium is required to control the signal.

[0044] In one embodiment, a network of thermo-optical switches is used to create a multiplexing unit 312 on a silicon nitride photonic chip. Other materials suitable for the multiplexing unit 312 include silicon dioxide, oxynitride, lithium niobate, III-V semiconductor materials, Silicon on Insulator (SOI), gallium arsenide (GaAs), silicon carbide, or optical grade polymers. Other modulation effects that support optical switching operations include electro-optical effects, charge carrier density effects, photomechanical effects, liquid crystal-based refractive index modulation, etc. Multiplexing functions can also be obtained under miniaturization and packaging constraints through microelectromechanical (MEMS) devices. The connection between the wire 318 and the multiplexing unit 312 can be achieved via separate wire bonding or welding, or by means of an intermediate substrate, which allows flip-chip assembly in individual or batch processing. In one embodiment, the intermediate substrate is flexible.

[0045] In one embodiment, the multiplexing unit 312 is assembled on a flexible substrate. The method for forming optical elements on a flexible substrate includes a substrate transfer post-processing step applied to a silicon-on-insulator (SOI) chip or wafer, as described in more detail in U.S. Patent No. 9,062,960, the disclosure of which is incorporated herein by reference in its entirety. In one embodiment, the resulting flexible device is thinner (less than 350 μm) than the starting thickness (500-700 μm). The multiplexing unit 312 can be implemented by a partially flexible optical integrated chip. According to an embodiment, the multiple waveguides 304 (e.g., optical fibers) are moderately flexible in order to reach the various observation ports 302 arranged in the distal section 104a. As Figures 3C to 3G As shown, the optical integrated chip can be formed by a series of interconnected rigid parts connected by flexible parts. The associated electronic parts 314 can be connected to the bottom side or the upper side of the integrated chip containing the multiplexing unit 312. In another embodiment, the multiplexing unit 312 and the associated electronic parts 314 are both arranged on a flexible substrate. In one example, the flexible substrate with both the multiplexing unit 312 and the associated electronic parts 314 is rolled into a cylindrical shape to be assembled in the distal section 104a of the catheter 100.

[0046] like Figure 3A As shown, the distal segment 104a may include one or more irrigation channels 310 to deliver fluid to a plurality of holes (not shown) on the exterior of the distal segment 104a. The fluid delivered via the irrigation channels 310 may be used for cooling during an ablation procedure. In other embodiments, the irrigation channels 310 may be designed to deliver a therapeutic fluid to the sample 308.

[0047] The distal section 104a may also include a force sensor 317. In one embodiment, the force sensor 317 is designed to measure the force applied to the distal section 104a during operation along one or more reference axes. The force sensor 317 may include a rigid element from the sheath (e.g., a rigid wire) that is mechanically connected to a portion of the sensor. The overall assembly of the catheter and any mechanical fixing elements acting between the distal section 104a and the sheath must ensure that sufficient pressure is transmitted to the force sensor 317. In another embodiment, the force sensor 317 may be a pressure-based sensor, such as a strain gauge.

[0048] According to an embodiment, the force sensor 317 may have its own readout element, defined in the same substrate as the multiplexing unit 312. The readout principle may be based on interference analysis of distance changes associated with strain, on spectral analysis based on resonant devices, on piezoelectric devices, on capacitive measurements, or on electromagnetic measurements. According to one embodiment, the signal generated by the force sensor 317 is propagated through an additional cable and / or an optical transmission medium running through the sheath 106. Alternatively, the signal may be propagated via the same electrical and optical paths used for the multiplexing unit 312 and its associated electronic parts 314. In the latter case, the multiplexed optical path and the data path of the force sensor 317 may be separated by appropriate signal multiplexing techniques. In addition, if the irrigation channel 310 is irrigated at a low flow rate and a constant flow rate, the pressure may be indirectly measured by adding a pressure transducer in the proximal section 102 of the catheter 100.

[0049] In one embodiment, a temperature sensor 319 may be included in the distal section 104a, substantially measuring the temperature at the tip of the catheter during operation. Figure 3A and Figure 3B Only one temperature sensor 319 is shown, but there may be any number of temperature sensors 319 in the distal section 104. The temperature sensor 319 may be a thermally coupled element, an element having a known resistance dependence on temperature, an element whose optical parameter varies with temperature, or any other type of temperature sensor. The temperature sensor 319 may include an element defined in the same substrate as the multiplexing unit 312. According to one embodiment, the signal generated by the temperature sensor 319 is propagated through additional cables and / or optical transmission media passing through the sheath 106, or through the same electrical and optical paths used for the multiplexing unit 312 and its associated electronic parts 314. In the latter case, the multiplexed optical path and the data path of the temperature sensor 319 may be separated by appropriate signal multiplexing techniques.

[0050] In some embodiments, the distal section 104 may include one or more electrodes for measuring tissue electrocardiograms, and / or one or more magnetic sensors for allowing catheter navigation. For example, one or more magnetic sensors of the catheter may be combined with an externally generated magnetic field generator to navigate the catheter with a magnetic field.

[0051] Figure 3BAnother embodiment of a distal segment depicted as distal segment 104b is shown. Distal segment 104b includes many of the same elements described in distal segment 104a. However, distal segment 104b does not include a multiplexing unit 312 and associated electronic parts 314. Fiber bundles 305 are used to provide light to multiple waveguides 304 within distal segment 104b. In catheter embodiments using distal segment 104b, the multiplexing unit can be located within proximal segment 102 or outside catheter 100 (e.g., with processing device 108).

[0052] exist Figure 3A and Figure 3B In any of the illustrated embodiments of the distal segment 104, the plurality of viewing ports 302 may include one or more lenses and / or mirrors or similar optical elements designed to focus light passing through any of the viewing ports 302. According to one embodiment, the material used within each viewing port 302 is substantially transparent to the wavelength range of light used for optical interrogation and the wavelength range of light used for laser ablation. For example, the material used within each viewing port 302 is substantially transparent to 1.3 μm optical tissue assessment and 980 nm or 1060 nm laser ablation. The optical elements may be coated with an anti-reflection layer to minimize optical losses. The mirrors may be locally created by selectively evaporating a mask on the surface of a metal layer to make it reflective and may be flat or provide a focusing function. In some embodiments, total internal reflection (TIR) ​​mirrors, which do not require metal coating, may also be used to redirect and / or focus light. The body of the distal segment 104 may be formed using injection molded plastic and may be designed to support packaging of the multiplexing unit 312. In one embodiment, the optical elements used at the plurality of viewing ports 302 include gradient index lenses and / or lenses with tapered tips.

[0053] In one embodiment, one or more of the plurality of viewing ports 302 include a scanning element (not shown) that allows for scanning of one or more beams exiting through the viewing port 302 (e.g., one or more exposure radiation beams and laser ablation energy) in a given direction. The scanning element may include a micro-electromechanical system (MEMS) component, or use an electro-optical modulator to control the radiation beam exit angle of the associated viewing port. Further details and examples regarding scanning of radiation beams may be found in U.S. Pat. No. 9,354,040, the disclosure of which is incorporated herein by reference in its entirety. In some embodiments, the scanning of the exposure radiation may collect an optical coherence tomography (OCT) image of the sample.

[0054] Figures 3C to 3GAdditional embodiments of the distal segment 104 are shown. These embodiments include many Figure 3A and Figure 3B The same elements are described in the examples unless otherwise specified. Figures 3C to 3G A distal segment including a photonic integrated circuit is shown having a rigid segment joined by a flexible segment. Figure 3C As shown, a single substrate 320 can serve as the base for all rigid beam input / output segments 322. Each rigid beam input / output segment 322 is connected to at least one thin and flexible segment 324. The beam input / output segments 322 can provide optical ports and are optically and mechanically interconnected by the flexible segments 324 to form the tip of the distal segment 104. Thus, the substrate 320 has a plurality of integral branches, each branch comprising rigid beam input / output segments 322 interconnected by flexible segments 324. The branches are bent around the distal end tip at the flexible segments 324. In this way, different shapes and arrangements can be accommodated. The retainer (at Figure 3F and Figure 3G ) can be used to maintain the spatial relationship between the branches and the corresponding rigid beam input / output sections 322.

[0055] The flexible waveguide may extend across the flexible section, optically connecting the optical port to the multiplexer 312. The substrate may be thinned by removing a portion of the substrate material to form the flexible section. A layer of polyimide may be added to strengthen the thinned portion. The multiplexer 312 may be formed in a manner such as Figure 3C The optical couplers 312 may be arranged on the rigid segments as shown, or across the rigid segments and the flexible segments. Although it is easier to form the optical ports on the rigid segments, the optical ports may also be formed on the flexible segments. In one embodiment, the optical couplers, such as 2x 1 or 2x 2, may be appropriately dispersed on the rigid and / or flexible segments to form part of the multiplexer 312.

[0056] The beam input / output section 322 can output a focused beam or an unfocused beam from the optical port. In addition, the beam can be emitted in the plane of the beam input / output section 322 (e.g. Figure 3D ), or may be emitted at an oblique angle to the plane of the beam input / output section 322, for example, orthogonal to the plane (as shown in FIG. Figures 3E to 3G ). Radiation can then be received from the sample along the same optical path. Figures 3E to 3G Various embodiments of devices designed to direct a radiation beam are shown. Further details and alternative arrangements may be found in US Pat. No. 9,690,093, the disclosure of which is incorporated herein by reference in its entirety.

[0057] Figure 3DTwo beam input / output sections 322 are shown, optically and mechanically coupled to the flexible section 324. The waveguide 334 extends along the plane of the substrate to the optical port 326, wherein the optical port 326 is configured to direct the beams of exposure radiation and laser ablation energy to the target tissue. The optical port 326 directs the radiation beam 342 substantially parallel to the plane of propagation along each respective beam input / output section 322. The optical port 326 can also direct the exposure radiation and laser energy to deliver the light to the area of ​​interest without aligning the optical port 326 and the viewing port 302. The beam input / output section 322 is not limited to a single optical port, but can have multiple optical ports.

[0058] Figures 3E to 3G The concept of directing a radiation beam at an angle substantially perpendicular to the substrate surface is shown. However, these embodiments differ in the placement and formation of certain elements. For example, Figure 3E A substrate 320 is shown mechanically and optically coupled by a plurality of beam input / output sections 322, which are mechanically and optically coupled to a flexible section 324. The lower portion of the flexible section has been removed to impart flexibility. One or more waveguides 334 are formed on each beam input / output section 322. The waveguide 334 can extend across the flexible section 324 to allow optical coupling between optical ports. The waveguide 334 includes a core layer 336 surrounded by cladding layers 338a and 338b. A reflector 340 is formed in a plane with the waveguide 334 and is designed to reflect a radiation beam 342 to the viewing port 302.

[0059] Substrate 320 can be any suitable material that allows for surface and / or bulk micromachining patterning steps. In one example, substrate 320 is a crystalline material such as silicon dioxide, silicon, gallium arsenide, indium phosphide, etc. In other examples, substrate 320 is amorphous, such as glass or polycrystalline silicon. The core layer 336 of waveguide 334 may include a material having a higher refractive index than cladding layers 338a and 338b so as to limit the radiation beam propagating through waveguide 334. For example, core layer 336 may include silicon nitride (Si3N4). Waveguide 334 may have a crystalline structure or be a polymer. For example, waveguide 334 may be formed of one or more materials that are transparent at wavelengths used for tissue assessment and laser ablation, and are capable of implementing a phase shift mechanism and handling high light intensities with negligible nonlinear effects. In one example, cladding layers 338a and 338b are silicon dioxide, substrate 320 is silicon, and core layer 336 is silicon oxide. The waveguide 334 may be a strip waveguide, a ridge waveguide, an optical fiber laid across the surface of the substrate 320, or any other type.

[0060] According to an embodiment, the reflector 340 may be formed by etching the layers that form the waveguide 334. A wet anisotropic etchant (e.g., tetramethyl ammonium hydroxide (TMAH) and / or potassium hydroxide (KOH)) may be used to strip material along crystal planes to form the surface of the reflector 340. The surface may be further smoothed by thermal oxidation of silicon and oxide removal processes by quickly exposing the reflector 340 to another chemical etchant, such as hydrofluoric acid (HF). Dry etching techniques may also be used to produce the angular surface of the reflector 340. For example, reactive ion etching (RIE) using a grayscale mask to produce different heights of photoresist may be used to produce non-planar structures. According to one embodiment, the reflector 340 is placed at a short distance from the end of the waveguide 334. The distance should not be too large, otherwise the radiation beam emitted from the waveguide 334 will propagate too far and undesirable optical losses will occur. In this embodiment, the reflector 340 and the waveguide 334 are patterned in the plane of the first surface of the substrate 320. The reflector 340 can be designed to have an angled slope. For example, the surface of the reflector 340 can be substantially at a 45-degree angle relative to the first surface of the substrate 320. This angle guides the radiation beam approximately at an angle perpendicular to the surface of the substrate 320. In another example, the surface of the reflector 340 is substantially at a 54.74-degree angle relative to the first surface of the substrate 320. Figure 3E In the embodiment of FIG. 3 , the light is reflected upward and away from the rigid beam input / output section 322 toward the viewing port 302. The viewing port 302 may include focusing optics, such as a lens, to focus the diverging radiation beam.

[0061] Figure 3FAn alternative arrangement is shown that does not require additional focusing elements. Alternatively, according to an embodiment, the optical element 344 is disposed above the waveguide 334 and above the top surface of the rigid beam input / output section 322. In this embodiment, the optical element 344 is a lens. The lens can be designed to focus the radiation beam 342 or collimate the radiation beam 342. The optical element 344 can be manufactured using standard photolithography etching using nanoimprint lithography or grayscale masks. Thermal reflow of transparent polymers can also be used to form curved lens shapes. The optical element 344 can be manufactured directly in the substrate 320 using reactive ion etching (RIE). When the substrate material has a high refractive index (e.g., materials such as silicon, indium phosphide, etc.), the advantages of using reactive ion etching (RIE) can be achieved, and therefore, the performance of the lens is almost independent of the refractive index of the surrounding medium. The curvature and position of the focusing surface of the lens can be adjusted so that the focus and focal length of the lens achieve the desired collimation or focusing performance. In one example, an intermediate polymer layer is introduced between the optical element 344 and the waveguide 334 to set the lens working distance. The optical element 344 may then be coated with an anti-reflection dielectric stack to minimize optical losses. Although the depicted arrangement has the optical element 344 on the same side of the substrate 320 as the waveguide 334, the waveguide 334 may have an opening in the rigid beam input / output section 322 on the opposite side of the optical element 344 to allow radiation to pass through the substrate 320.

[0062] The single crystal holder 350 includes a groove 352 to physically hold and guide the rigid beam input / output section 322 . Figure 3F The cross-sectional view in FIG. 1 shows how the substrate 320 can be bent around a holder 350. The holder 350 surrounds the tip of the distal end 104, fixes the rigid beam input / output section 322 in space, and the flexible section 324 spans the portion of the holder between the grooves 352. Although two rigid beam input / output sections 322 are shown in detail, each groove 352 typically has a corresponding rigid beam input / output section 322 therein. Additional grooves may be provided in the holder 350 for the flexible section 324. The holder 350 may alternatively be formed as a frame rather than a single crystal element.

[0063] Figure 3G Another alternative arrangement is shown that includes a focusing element, thereby alleviating the need for a focusing element in the viewing port 302. Figure 3F The refractive element shown in Figure 3GThe arrangement in includes an optical element 344 having a reflective coating 346. The reflective coating 346 can be formed on a parabola of the optical element 344 to focus or collimate the light from the waveguide 334. As described above, the optical element 344 and the reflective coating 346 can be formed on a rigid beam input / output section 322. Alternatively, the reflective coating 346 can be formed on a parabola formed within a groove 352 of a holder 350, thereby eliminating the need for additional optical elements. The reflective coating 346 can be designed for on-axis or off-axis reflection. For on-axis reflection, a substantially annular opening can be formed in the beam input / output section 322 to allow the beam 342 to pass through the substrate 320 and around the planar reflector 340.

[0064] In addition, the above Figures 3D to 3G The described features may be combined to provide a variety of means of directing radiation beam 342 .

[0065] Figure 4A 1 shows a view of the outside of the distal segment 104 according to an embodiment. A plurality of viewing ports 302 may be located anywhere around the entire outer surface of the distal segment 104 for providing viewing of a tissue sample (e.g., an atrial wall) at any angle around the distal segment 104 and ablating a portion of the tissue sample by laser ablation. In addition, the distal segment 104 may include a plurality of viewing ports 302 that are located anywhere around the entire outer surface of the distal segment 104 and for providing viewing of a tissue sample (e.g., an atrial wall) at any angle around the distal segment 104 and ablating a portion of the tissue sample by laser ablation. Figure 3A and Figure 3B 310. The plurality of viewing ports 302 and the openings 402 are associated with the irrigation channels 310 shown in FIG. The openings 402 may also be placed anywhere around the outer surface of the distal section 104 and used to drain liquid to or aspirate liquid from the area around the distal section 104. In one embodiment, the plurality of viewing ports 302 and the openings 402 may be placed at the same location on the outer surface of the distal section 104.

[0066] Figure 4B An exploded view of the distal segment 104 according to an embodiment is shown. A plurality of optical elements 404 can be located anywhere around the entire outer surface of a cap 410 for providing arbitrary angle viewing of a tissue sample (e.g., atrial wall) around the distal segment 104 and ablating a portion of the tissue sample by laser ablation. The cap 410 is designed to be mounted around a holder 350 and a base plate 320. The rigid beam input / output section 322 is assembled in a groove 352 of the holder 350. The cap 410 is then assembled on the holder 350 and the base plate 320 and secured by alignment and locking mechanisms 412 and 414. The detent 412 is assembled in the intention 414 to secure the cap 410 to the holder 350 while allowing optical connection to the proximal segment 102. By securing the cap 410 to the holder 350, the optical elements 404 will be aligned with the optical output of the rigid beam input / output section 322.

[0067] In some embodiments, alignment between optical element 404 and the optical output may not be required to perform combined optical tissue assessment and laser ablation. That is, cover 410 may include a material that is substantially transparent to the wavelength range of light for optical interrogation and the wavelength range of light used for laser ablation. For example, the material of cover 410 is substantially transparent to optical tissue assessment at 1.3 μm and laser ablation at 980 nm or 1060 nm. In some cases, cover 410 may include an anti-reflective coating to avoid undesirable back reflections and provide maximum transmitted energy to the tissue.

[0068] Merging Optical Evaluation and Laser Ablation Examples

[0069] Figure 5A and Figure 5B An example block diagram of a combined optical evaluation and laser ablation system for a catheter according to an embodiment of the present disclosure is shown. Figure 5A An example system 500 is shown having a first light source 502, a second light source 504, a first isolation element 503, a second isolation element 505, a coupling element 506, a beam splitter 508, a first multiplexer 510, a second multiplexer 512, and a coupling element 513. In some embodiments, each component of the system 500 is housed within a catheter, such as the catheter 100. For example, the first light source 502 and the second light source 504 may be located within the proximal section 102 or the processing device 108 of the catheter 100. In some embodiments, the first light source 502 generates a radiation beam source for optically evaluating a sample 514 at a wavelength of approximately 1.3 μm, while the second light source 504 generates laser energy for tissue ablation of the sample 514 at a wavelength of approximately 980 nm or 1060 nm. The first isolation element 503 and the second isolation element 505 may include an optical circulator or isolator that may be inserted into the catheter to avoid possible damage to the first light source 502 and the second light source 504 due to undesirable back reflections. The coupling element 506 is configured to optically couple the first light source 502 and the second light source 504. One or more exposure radiation beams and laser ablation energy beams generated by the first light source 502 and the second light source 504 may be optically coupled in the proximal section 102 of the catheter 100 through the coupling element 506. For example, the coupling element 506 may be a fiber optic coupling element, wherein the fiber optic coupling element allows the first light source 502 and the second light source 504 to be coupled before being emitted into the substrate of the catheter.

[0070] In some embodiments, the coupling element 506 can couple the first light source 502 and the second light source 504 in a single optical fiber so as to propagate more than one exposure radiation beam and the laser ablation energy beam in the same optical fiber in the sheath 106 of the catheter 100. The beam splitter 508 can separate more than one exposure radiation beam from more than one laser energy beam (or laser ablation energy) at the distal section 104 of the catheter 100. In some embodiments, the beam splitter 508 and / or the coupling element 506 can be located in the processing device 108 or the proximal section 102 of the catheter 100. After beam isolation, the first multiplexer 510 can direct more than one exposure radiation beam to multiple optical ports 326 of the distal section 104 of the catheter 100. In some embodiments, the first multiplexer 510 can include a passive multiplexer (e.g., a distribution tree) or an active multiplexer (e.g., a switch), in which more than one exposure beam can be directed to more than one optical port 326. The second multiplexer 512 can direct the laser energy to at least one of the multiple optical ports 326 of the distal section 104 of the catheter 100. The one or more exposure radiation beams and the laser energy from the first multiplexer 510 and the second multiplexer 512 can be coupled through a coupling element 513, which can be a fiber optic coupling element. Then, the one or more exposure radiation beams and the laser ablation energy can be emitted to the sample 514 from the multiple optical ports 326. In some embodiments, the first multiplexer 510 and the second multiplexer 512 can be located in the distal section 102 or the proximal section 104 of the catheter 100. In other embodiments, a single multiplexer can be used to multiplex the laser ablation energy and one or more exposure radiation beams to at least one of the multiple optical ports 326. Although Figure 5A The first multiplexer 510 and the second multiplexer 512 are shown as having only one input and one output, but the first multiplexer 510 and the second multiplexer 512 in the system 500 may include any number of inputs and any number of outputs.

[0071] Figure 5B Another example system 520 is shown having a first light source 522, a second light source 524, a first isolation element 526, a second isolation element 528, a coupling element 530, and a multiplexer 532. In some embodiments, each component of the system 520 is housed within a catheter, such as catheter 100. For example, the first light source 522 and the second light source 524 may be located within the proximal section 102 of the catheter 100 or within the processing device 108. In some embodiments, Figure 5B The first light source 522 and the second light source 524 in the embodiment can be Figure 5AThe first light source 502 and the second light source 504 in the system 520 are the same. In the system 520, one or more exposure radiation beams and laser ablation energy beams from the first light source 522 and the second light source 524 can be propagated down to the sheath 106 of the catheter 100, such as in two separate fibers (for example, one fiber optically evaluates the sample 524 with one or more exposure radiation beams, and the other fiber ablates a portion of the sample 524 with one or more laser ablation energy beams). The first isolation element 526 and the second isolation element 528 can include optical circulators or isolators that can be inserted into the catheter to avoid possible damage to the light sources due to undesirable back reflections. The one or more exposure radiation beams and the laser ablation energy beam can be optically coupled by a coupling element 530. In some embodiments, the coupling of the one or more exposure radiation beams and the laser ablation energy beam occurs in the distal section 104 of the catheter 100. The multiplexer 532 can then direct the one or more exposure radiation beams and the laser energy to at least one of the multiple optical ports 326 of the distal section 104 of the catheter 100. In some embodiments, two multiplexers may be used to multiplex the laser energy and one or more exposure radiation beams to one or more optical ports of the plurality of optical ports 326, respectively. In other embodiments, the multiplexer 532 may be located in the distal section 102 or the proximal section 104 of the catheter 100. Figure 5B Multiplexer 532 is shown having only one input and one output, but in system 520, multiplexer 532 may include any number of inputs and any number of outputs.

[0072] The combined optical assessment and laser ablation catheter as described herein can be further configured to perform temperature measurements. For example, a detector (e.g., located in the processing device 108, or in the proximal section 102 or the distal section 104 of the catheter 100) can measure the black body spectrum emitted by the tissue to determine one or more temperatures of the target tissue before, during, or after laser ablation. Figure 6 An example graph of a blackbody spectrum at different wavelengths and temperatures measured by an ablation catheter according to an embodiment of the present disclosure is shown. In order to measure temperatures within a range of human tissue temperatures (e.g., from 37°C to 80°C during ablation), the catheter's detector may be sensitive to wavelengths starting at around 2 μm, such as Figure 6 shown.

[0073] In some embodiments, for low loss and broadband, the combined optical evaluation and laser ablation catheter can be achieved using silicon nitride as the waveguide material. Silicon nitride can allow optical waveguide losses as low as 0.7 dB / m, and the material can be transparent from approximately 400 nm (silicon nitride bandgap) to 4000 nm (silicon oxide SiO2 absorption). In some embodiments, as the wavelength of interest (e.g., 980 nm for laser ablation, 1300 nm for optical tissue evaluation, 2000 nm for temperature measurement), the silicon nitride material can also have a higher refractive index than the silicon dioxide material. Table 1 provides the values ​​of the refractive index of two materials, silicon nitride (Si3N4) and silicon dioxide (SiO2), measured by plasma-assisted chemical vapor deposition (PECVD), as a function of wavelength.

[0074] Table 1: Measured refractive index values ​​for silicon nitride and silicon dioxide

[0075]

[0076] Figure 7 An example diagram of a layer stack for a silicon nitride waveguide is shown in accordance with an embodiment of the present disclosure. Figure 7 The waveguide of exemplifies a 1-μm wide and 1-μm high silicon nitride waveguide symmetrically embedded in a silicon dioxide (SiO2) box. The embedded waveguide can be grown on a silicon wafer to produce a photonic integrated circuit having a rigid section (e.g., rigid section 322) connected with a flexible section (e.g., flexible section 324). In the flexible section of the waveguide, the silicon substrate can be removed from the material stack, among other possible changes.

[0077] In some embodiments, during the design of the focusing optics of the substrate that incorporates optical evaluation and laser ablation catheters, the tissue evaluation function may be prioritized. For example, a design wavelength of about 1300 nm may be required to achieve a depth of focus (DOF) of 1.5 mm in the tissue to accurately evaluate lesion transmurality. According to one embodiment, to achieve the desired depth of focus (DOF) in the tissue, a waist beam diameter of about 30.54 μm may be used at the focus, which is placed at a distance of half the depth of focus (DOF) from the outer wall of the housing, such as 0.75 mm. Figure 8An example diagram of an apparatus 800 designed to guide a radiation beam according to an embodiment of the present disclosure is shown. The apparatus 800 includes a substrate 802, a waveguide 804 having a core layer 806 and cladding layers 808a and 808b. In one embodiment, the substrate 802 may be silicon, the core layer 806 may be silicon nitride, and the cladding layers 808a and 808b may be silicon dioxide.

[0078] In one embodiment, the reflector 810 is formed by facets at the end of the waveguide 804. In this way, the radiation beam 812 is reflected downward to the substrate 802 before it is emitted from the waveguide 804. According to one embodiment, an antireflective (AR) coating 816 can be included at the interface between the waveguide 804 and the substrate 802. The antireflective (AR) coating 816 can be patterned so that it only exists below the reflector 810. In another example, the antireflective coating 816 covers a larger area on the surface of the substrate 802. The antireflective (AR) coating 816 can be present on the entire surface of the substrate 802. Figure 8 Further shown are optical element 814 (e.g., lens, reflector, etc.), housing 821, depth of focus (DOF) 822, and anti-reflection (AR) coatings 823 and 824. In one example, at a wavelength of 1300 nm, the refractive index (n0) of cladding layer 808b, the refractive index (n1) of anti-reflection coating 816, which may include silicon nitride or a more suitable material, and the refractive index (n2) of substrate 802 are 1.4576, 1.8729 (if silicon nitride is considered), and 3.5226, respectively. In some embodiments, the radius of curvature of optical element 814 and the thickness of substrate 802 can be designed to produce a desired waist beam diameter of about 30.54 μm at the focal plane. The focal plane can be at half of the depth of focus 822 and can correspond to the plane where the beam size is smallest.

[0079] Fig. 9A and Fig. 9B , respectively, show example graphs of reflection as a function of wavelength and layer thickness according to embodiments of the present disclosure. Fig. 9AAs shown, the reflection of the substrate 802 with an antireflective (AR) coating 816 is optimized at 1300nm. The ideal material that results in zero reflection consists of a layer with a thickness of about 144nm and a refractive index n1=2.2659. In addition to the ideal candidate material, the performance of having silicon nitride as an antireflective (AR) coating 816 is also considered. In this case, when a silicon nitride layer thickness of 174nm is achieved, the minimum reflection reaches about 3.5%. Not having any antireflective (AR) layer (e.g., antireflective coating 816) will result in a reflection of 9.34% at 1300nm. By implementing an antireflective (AR) coating 816 at the interface between the waveguide 804 and the substrate 802, the reflection from the substrate can be reduced to improve the performance of the system.

[0080] In some embodiments, to avoid undesired back reflections from the lens interface, an anti-reflection (AR) layer 820 is provided on the lens, such as Figure 8 . In some embodiments, the anti-reflection (AR) layer 820 may be designed to account for having saline (or any other fluid used in an ablation procedure) in an irrigation catheter. For example, changes in the refractive index caused by saline or other fluids may require changes in the refractive index and thickness of the anti-reflection (AR) layer 820 to ensure reduced reflections, and the anti-reflection (AR) layer 820 may be designed accordingly to account for these changes. In some embodiments, in a non-irrigation method, the anti-reflection (AR) layer 820 may be designed to account for the presence of air in the environment surrounding the lens. For example, changes in the refractive index caused by air in a non-irrigation catheter may require changes in the refractive index and thickness of the anti-reflection (AR) layer 820 to ensure reduced reflections. In some embodiments, it is also possible to not align with the lens using an irrigation method such as an irrigation hole in the cover (e.g., the cover 410).

[0081] In another embodiment, the anti-reflection (AR) layer 820 comprises silicon nitride. In some embodiments, the anti-reflection (AR) layer 820 has negligible reflection if used in air at a layer thickness of about 174 nm, and reaches a reflection value of about 2% when salt water is in contact with the lens. Similarly, the anti-reflection coatings 823 and 824 can be similarly designed to avoid unwanted reflections in the inner and outer surfaces of the cover 821.

[0082] Fig.10 An example environment of a waveguide with a flushing method according to an embodiment of the present disclosure is shown. Fig.10 A ray tracing-based simulation is shown, which corresponds to a development method using OpticStudio, a commercially available design software from ZEMAX LLC. In this example, Fig.10A silicon nitride waveguide having a core layer 1006 with a cross section of 1 μm x 1 μm, a 5 μm thick silicon dioxide layer 1008b, and a silicon substrate material 1002 are shown. In some embodiments, the core layer 1006, the silicon dioxide layer 1008b, and the substrate 1002 are shown. Figure 8 806, cladding layer 808b and substrate 802 in FIG.

[0083] In some embodiments, Fig.10 The waveguide may include a lens (e.g., optical element 814), and the radius of curvature of the optical element and the thickness of the substrate 1002 may be designed to produce a desired waist beam diameter of approximately 30.54 μm at the focal plane. In some cases, the focal plane may be at a distance of depth of focus (DOF) / 2 from the outer wall of the cover (e.g., cover 821). For example, the distance between the lens and the outer wall of the cover may be 0.5 mm, which includes the thickness of the cover, and the total distance between the lens and the focal plane may be fixed and equal to 1.25 mm. In one embodiment, the optimal radius of the lens (e.g., optical element 814) and the thickness of the substrate (e.g., substrate 1002) may be 116 μm and 181 μm, respectively. For example, these design parameters may result in a waist beam diameter at the focal plane of 28.82 μm.

[0084] Fig.11 The example diagram shows the focal plane position of each wavelength at the corresponding depth of focus (DOF) value according to an embodiment of the present disclosure. In some embodiments, the depth of focus (DOF) value used for tissue assessment and temperature monitoring exceeds the depth of focus (DOF) value corresponding to laser ablation, so that the laser ablation surgery can be accurately assessed. In particular, compared with the depth of focus (DOF) used for laser ablation, tissue assessment and temperature monitoring may be performed at a deeper depth in order to grasp the progress of the surgery and ensure the safety of the patient.

[0085] High Power Considerations for Catheter Embodiments

[0086] In some embodiments, high power may be considered for catheters incorporating optical evaluation and laser ablation systems. For example, the power of the laser ablation energy used to ablate tissue is on the order of tens of watts. With high optical intensities, the light-matter interaction may become nonlinear. In one embodiment, laser ablation energy with a wavelength of 980 nm and a power of up to 12 W may be delivered to the target tissue. For example, in a cross-sectional area of ​​1 μm 2 In one embodiment of an embedded silicon nitride waveguide, the power density reaches about 1.2 GW / cm 2In this embodiment, due to the relatively large optical intensity propagating through the waveguide, some nonlinear effects may become very important, such as Two-Photon Absorption (TPA), nonlinear losses and refractive index, Four-Wave Mixing (FWM), Self-Phase Modulation (SPM) and Cross-Phase Modulation (XPM). In the presence of nonlinear losses, the total loss coefficient can be described in Equation 1 as:

[0087] α=αL+α NL (|E| 2 ) (1)

[0088] where α L ,α NL and |E| 2 The linear loss contribution, nonlinear loss contribution and optical intensity are explained respectively.

[0089] In the two-photon absorption (TPA) process, the band gap energy of a specific material may be bridged by the energy absorption of two photons, thereby exciting electrons from the valence band to the conduction band. This process can cause nonlinear losses α NL，TPA , which depends on the light intensity according to Equation 2:

[0090] α NL，TPA =α2(|E| 2 ) (2)

[0091] Where α2 is the TPA (Two-Photon Absorption) coefficient. The energy band gap of silicon nitride can be calculated by the following equation 3:

[0092]

[0093] where h, c, n and λ0 are Planck constants (h = 4.136·10 -15 eV·s), the speed of light in vacuum, the refractive index of silicon nitride (n0 = 1.9378) and the starting wavelength of about 400nm. On the other hand, the band gap at the laser ablation wavelength (e.g. 980nm) can be calculated by equation 4:

[0094]

[0095] Equations 3 and 4 show that TPA (Two-Photon Absorption) should not occur in silicon nitride at 980 nm because the photon energy at this wavelength is less than E g(SiN) / 2. In addition, 1.2GW / cm 2 The light intensity of 1 ensures the linear regime in the waveguide, since nonlinear losses are usually induced by the power density, which is usually at least one order of magnitude higher.

[0096] In some embodiments, high optical intensity may also result in a nonlinear refractive index, where the dependence may be written as shown in Equation 5:

[0097] n(ω,|E| 2 )=n0(ω)+n2|E| 2 (5)

[0098] where E is the electric field amplitude, and n2 is related to the third-order material sensitivity χ in Equation 6. (3) The associated nonlinear Kerr coefficient.

[0099]

[0100] In one example, the nonlinear Kerr coefficient was experimentally measured in a silicon nitride waveguide to be n2=2.4·10 -15 cm 2 / W. This measurement indicates that the refractive index change at 980nm is 2.88·10 -6 , which is an order of magnitude lower than the efficiency of the thermo-optical effect in silicon nitride.

[0101] In χ (3) In the material, the third-order polarization term may involve nonlinear interactions of four waves and lead to a four-wave mixing (FWM) phenomenon. In one embodiment, the four-wave mixing (FWM) may be derived from the refractive index adjustment caused by radiation, as shown in Equation 5, where E(t) = E1cos(2πf1t) + E2cos(2πf2t) + E3cos(2πf3t), where f1 = 0.15·10 15 Hz, f2=0.231·10 15 Hz and f3=0.306·10 15 Hz. Frequencies f1, f2, and f3 correspond to the frequencies of the temperature monitoring, tissue assessment, and ablation systems, respectively. Therefore, the generation of light at the new frequencies is detailed in Table 2 below:

[0102] Table 2: Generated frequency values

[0103]

[0104]

[0105] In some embodiments, the new frequencies below 400 nm and above 4000 nm in Table 2 may not propagate due to the silicon nitride band gap and silicon dioxide absorption. In addition, since the optical intensity of the temperature signal is very low (e.g., according to Figure 6 ), so the frequency (f1) generated by the temperature signal is negligible. Therefore, with respect to the operating wavelengths for tissue evaluation and temperature monitoring, new frequencies with associated intensity values ​​are generated, which are frequencies centered around 2f2-f3, 2f3-f2, and 3f2. In some embodiments, these wavelengths (1930nm, 786nm, and 433nm) may not interfere with the laser ablation wavelength (980nm), the optical evaluation wavelength (1250-1350nm), or the temperature measurement wavelength (above 2000nm). In other embodiments, a filter can be applied before the detector measures the temperature of the target tissue (e.g., at a wavelength of 2000nm) to filter out wavelengths below a predetermined wavelength (e.g., 1950nm). By utilizing more than one filter, the system can avoid erroneous temperature measurements of the target tissue.

[0106] In some embodiments, another consequence of the Kerr effect may be self-phase modulation (SPM). As derived from Equation 5, relatively large optical intensities may cause a change in the refractive index of the medium due to light-matter interaction. This change in refractive index produces a phase shift in the optical signal, which in turn causes a broadening of the spectrum. In some embodiments, this change may be insignificant to both the tissue assessment and temperature monitoring systems, as the change in the spectral characteristics of the laser ablation signal may not have any effect on it. However, in addition to self-phase modulation (SPM), cross-phase modulation (XPM) may also occur. Cross-phase modulation (XPM) is similar to self-phase modulation (SPM), but the phase shift caused by the light intensity affects other frequencies instead of the laser ablation frequency. The intensity of the cross-phase modulation (XPM) effect decreases with the wavelength detuning between the pump (laser ablation) and probe (tissue assessment) signals. Considering that the wavelength detuning may be greater than 300nm, this effect may not have any significant impact on the tissue assessment wavelength.

[0107] Exemplary Operation Methods

[0108] According to the embodiments described herein, the catheter 100 can be used to perform combined optical assessment, laser ablation, and temperature monitoring of target tissue. One or more of the multiple optical ports in the distal section 104 of the catheter 100 can ablate at least a portion of the tissue volume surrounding it. By adjusting the laser power and ablation time, the total laser energy delivered to the target tissue can be precisely controlled. In additional embodiments, the catheter can also provide temperature monitoring and additional cooling for the blood flow surrounding the target tissue.

[0109] As of now, various ablation methods and other embodiments of the ablation catheter having the above substrate can be implemented, for example, Figure 1 The catheter 100 shown in FIG. Figures 3A to 3G and FIG. 4A to FIG. 4B The distal section 104 is shown, and FIG. 5A to FIG. 5B The combined optical evaluation and laser ablation system shown, and Figures 6 to 11 The embodiment shown.

[0110] Fig.12 An example method 1200 for performing combined optical tissue assessment and laser ablation according to an embodiment of the present disclosure is shown. The method 1200 may be performed by an ablation catheter 100 as described herein.

[0111] At box 1202, an ablation catheter is provided. For example, an ablation catheter having a proximal end, a distal end having a plurality of optical ports, and a sheath coupled between the proximal end and the distal end. For example, the ablation catheter can include a holder that holds the plurality of optical ports in a fixed spatial relationship, and a shield that is substantially transparent at a wavelength of exposure radiation, a temperature monitoring system, and a wavelength of laser energy, wherein the shield is fixed to the holder and configured to cover the holder and the plurality of optical ports. At box 1204, more than one exposure radiation beam can be emitted to a sample through the plurality of optical ports. For example, the more than one exposure radiation beam can be provided from a first light source configured to generate an exposure radiation source beam. The more than one exposure radiation beam from the source beam can be directed to the plurality of optical ports by a multiplexer located in the proximal end or the distal end of the catheter.

[0112] At block 1206, one or more scattered or reflected radiation beams may be received from the sample through a plurality of optical ports. For example, the one or more scattered or reflected radiation beams may be guided by a light-transmitting medium in a catheter sheath.

[0113] At block 1208, laser energy output from at least a portion of the optical port may be used to ablate at least a portion of the sample. For example, laser energy may be provided from a second light source configured to generate laser energy. Laser energy from the second light source may be directed to at least one optical port via a multiplexer located in the proximal end or the distal end of the catheter.

[0114] It should be understood that it is the embodiments, rather than the content and abstract sections, that are intended to be used to interpret the scope of the claims. The content and abstract sections may set forth one or more but not all exemplary embodiments of the invention contemplated by the inventor, and therefore, are not intended to limit the invention and the appended claims in any way.

[0115] The implementation of specific functions and their relationships have been illustrated above with the help of functional building blocks, thereby describing the embodiments of the present invention. For ease of description, the boundaries of these functional building blocks are arbitrarily defined herein. As long as the specific functions and their relationships can be properly performed, alternative boundaries can be defined.

[0116] The above description of specific embodiments will fully reveal the general nature of the present invention, and those skilled in the art can easily modify and / or adapt various applications, such as specific embodiments, by applying the knowledge in the art without departing from the general concept of the present invention, without excessive experimentation. Therefore, based on the teachings and guidance given herein, such adaptations and modifications are intended to be within the meaning and scope of the equivalents of the disclosed embodiments. It should be understood that the wording or terminology herein is for the purpose of description rather than limitation, so that the terms or wording of this specification should be interpreted by those skilled in the art based on the teachings and guidance.

[0117] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A catheter system, comprising: Catheters, including: proximal segment; The distal segment includes: Multiple optical ports, configured as: transmitting one or more exposure radiation beams to the sample, receiving one or more scattered radiation beams that have been reflected or scattered from the sample, and emitting laser ablation energy to ablate at least a portion of the sample; and a holder configured to hold the plurality of optical ports in a fixed spatial relationship; and a sheath coupled between the proximal section and the distal section; A processing device comprising: a first light source configured to generate an exposure radiation source beam; a second light source configured to generate the laser ablation energy; a coupling element configured to optically couple the first light source and the second light source, the coupling element being housed within the conduit; and a beam splitter, housed within the catheter, configured to separate one or more exposure radiation beams from the laser ablation energy; and A multiplexer, housed within the conduit, is configured to: directing the isolated one or more exposure radiation beams from the radiation source beam to the plurality of optical ports; combining the more than one scattered radiation beams; and The isolated laser ablation energy is directed to at least one optical port of the plurality of optical ports. 2 . The catheter system of claim 1 , wherein the plurality of optical ports are formed on a substrate having a rigid section and a flexible section.

3. The catheter system of claim 2, wherein the plurality of optical ports are formed on the rigid sections of the substrate, wherein the rigid sections are interconnected with the flexible sections.

4. The catheter system of claim 1, wherein the coupling element couples the first light source and the second light source in a single optical fiber so as to propagate more than one exposure radiation beam and laser ablation energy beam in the same optical fiber in the sheath of the catheter.

5. The catheter system of claim 1, further comprising: A shield is substantially transparent at the wavelength of the one or more exposure radiation beams, the wavelength of the one or more scattered radiation beams, and the wavelength of the laser ablation energy, wherein the shield is fixed to the holder and configured to cover the holder and the plurality of optical ports. The catheter system of claim 1 , wherein the multiplexer is further configured to perform phase shifting.

7. The catheter system of claim 1, wherein the plurality of optical ports are further configured to receive one or more signals indicative of a temperature of the portion of the sample.

8. A catheter system for performing combined optical tissue assessment and laser ablation, the catheter system comprising: Catheters, including: proximal segment; Distal segment, including: Multiple optical ports, configured as: transmitting one or more exposure radiation beams to the sample, receiving one or more scattered radiation beams that have been reflected or scattered from the sample, and emitting laser ablation energy to ablate at least a portion of the sample; and a sheath coupled between the proximal section and the distal section; and A processing device comprising: a first light source configured to generate an exposure radiation source beam, and a second light source configured to generate the laser ablation energy, wherein the first light source and the second light source are optically coupled by a coupling element in the distal end or the proximal end of the catheter, The catheter system further comprises: a beam splitter, housed within the catheter, configured to separate one or more exposure radiation beams from the laser ablation energy; A first multiplexer, housed within the conduit, is configured to: directing the one or more isolated exposure radiation beams from the radiation source beam to the plurality of optical ports; and combining the more than one scattered radiation beams; and Second multiplexer, configured as: directing the isolated laser ablation energy to at least one of the plurality of optical ports indivual.

9. The catheter system of claim 8, further comprising: A holder is configured to hold the plurality of optical ports in a fixed spatial relationship.

10. The catheter system of claim 8, wherein the plurality of optical ports are formed on a substrate having a rigid section and a flexible section.

11. The catheter system of claim 8, wherein the coupling element couples the first light source and the second light source in a single optical fiber so as to propagate more than one exposure radiation beam and laser ablation energy beam in the same optical fiber in the sheath of the catheter.

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