Patent Description:
In the past, certain intravascular guidance of medical instruments, such as guidewires and catheters for example, have used fluoroscopic methods for tracking placement of medical instruments. However, such fluoroscopic methods expose patients and their attending clinicians to harmful X-ray radiation. Moreover, in some cases, the patients are exposed to potentially harmful contrast media needed for the fluoroscopic methods.

Recently, electromagnetic tracking systems have been increasingly used in medical applications. Although electromagnetic tracking systems avoid line-of-sight reliance in tracking a catheter, these systems are prone to intermittent failures caused by electromagnetic field interference. More specifically, since electromagnetic tracking systems depend on the measurement of magnetic fields produced by field generators, these systems are susceptible to electromagnetic field interference from cellular telephones, tablets, laptops and other consumer electronics that emit electromagnetic waves. As a result, electromagnetic tracking systems are being subjected to more frequent signal dropouts and are defined to a limited depth range for signal retrieval. <CIT> discloses a system comprising a tether having an instrument connected at one end. The tether contains fibers having sensors therein to allow a determination of the shape of the tether and to thereby determine a location of the end of the tether where it connects to the instrument. <CIT> discloses a catheter having a plurality of lumens therein. <CIT> discloses a catheter having one or more optical fiber sensors therein for determining a shape of the catheter. <CIT> discloses a catheter assembly having a sensor at an end thereof and wires contained in a lumen to connecting to the sensor.

Disclosed herein is a catheter with fiber optic shape sensing capabilities and methods of operation thereof, which is not subject to the disadvantages associated with electromagnetic tracking systems as described above.

According to a first aspect, there is provided a catheter according to claim <NUM>. The catheter features an elongated, integrated tubing, a septum (or septa), and a plurality of lumen formed between surfaces of the septum (or septa) and an inner surface of a wall of the integrated tubing (hereinafter, "tubing wall"). A plurality of micro-lumens are formed within the septum and within (or along) the tubing wall to retain a corresponding plurality of (optical) core fibers. According to one embodiment of the disclosure, each of the core fibers may constitute a single core grated fiber, namely a single light transmission medium such as a cylindrical element of glass or plastic with one or more sensors. Alternatively, according to another embodiment of the disclosure, each of the core fibers may constitute multiple (two or more) entwined transmission mediums with sensors.

More specifically, one embodiment of the catheter includes at least one septum spanning across a diameter of the integrated tubing and continuing longitudinally to subdivide an opening formed by the integrated tubing to produce two lumen. As described below, the septum is fabricated with a first micro-lumen of the above-identified plurality of micro-lumens, where the first micro-lumen is coaxial with a central axis of the integrated tubing by being positioned within a medial portion of the septum at or near a cross-sectional center of the integrated tubing. The first micro-lumen is sized to retain a core fiber (hereinafter, "center core fiber"), where the diameter of the first micro-lumen may be sized to exceed the diameter of the center core fiber. In lieu of a single septum, the catheter may include two or more septa extending radially from the cross-sectional center to the tubing wall. Also, the first micro-lumen may be maintained by a protruding portion of the integrated tubing in lieu of the septum or in other deployments, provided the first micro-lumen is positioned coaxial with the central axis.

The tubing wall includes one or more micro-lumens, such as a second plurality of micro-lumens that are a subset of the above-identified plurality of micro-lumens. According to one embodiment of the disclosure, each of the second plurality of micro-lumens may be positioned at the same known radius from the cross-sectional center of the integrated tubing along a circumference of the tubing wall. For example, the second plurality of micro-lumens may be laterally aligned (e.g., oriented in parallel with the central axis) and axially positioned along the outer circumference of the tubing wall to retain a corresponding plurality of core fibers (hereinafter, "outer core fibers"). Alternatively, as described below in detail, the second plurality of micro-lumens may be laterally aligned and positioned with the outer core fibers being coextruded within the tubing wall.

The second plurality of micro-lumens, in accordance with one embodiment of the disclosure, are sized to retain a corresponding plurality of core fibers (hereinafter, "outer core fibers"), where the diameter of each of the second plurality of micro-lumens may also be sized larger than the diameter of the outer core fibers to provide "play" and isolate the core fibers from forces applied to the catheter surface, but would not be experienced by the core fibers. Such isolation may provide more accurate shaping sensing determinations as the measurement of (mechanical) strain experienced by the core fibers, may allow a medical instrument monitoring system to identify, with greater precision, shape or form changes to the catheter, and in particular the integrated tubing of the catheter.

According to one embodiment of the disclosure, when deployed as a single core grated fiber, the core fiber includes a plurality of sensors spatially distributed along its length between at least the proximal and distal ends of the integrated tubing. These distributed sensors may be deployed as an array of reflective gratings and positioned at a different region of the core fiber to enable distributed measurements throughout the entire length or a selected portion of the integrated tubing. These distributed measurements may be signal characteristics obtained from reflected light of different spectral widths (e.g., specific wavelength or specific wavelength ranges). On example of a reflected light characteristic may include a wavelength shift in the reflected light caused by strain (e.g., axial strain or other types of mechanical strain).

According to one embodiment of the disclosure, each sensor may constitute a reflective grating such as a fiber Bragg grating (FBG), namely an intrinsic sensor corresponding to a permanent, periodic refractive index change inscribed into the core fiber. Stated differently, the sensor operates as a light reflective mirror for a specific spectral width (e.g., a specific wavelength or specific range of wavelengths). As a result, as broadband incident light is supplied by an optical light source and propagates through a particular core fiber, upon reaching a first sensor of the distributed array of sensors for that core fiber, light of a prescribed spectral width associated with the first sensor is reflected back to an optical receiver within a console, including a display and the optical light source. The remaining spectrum of the incident light continues propagation through the core fiber toward a distal end of the integrated tubing. The remaining spectrum of the incident light may encounter other sensors from the distributed array of sensors, where each of these sensors is fabricated to reflect light with different specific spectral widths to provide distributed measurements, as described above.

During operation, multiple light reflections (also referred to as "reflected light signals") are returned to the console from each of the plurality of core fibers residing within the corresponding plurality of micro-lumens formed within the catheter. Each reflected light signal may be uniquely associated with a different spectral width. Information associated with the reflected light signals may be used to determine a three-dimensional representation of a physical state (e.g., shape length, shape, form, and/or orientation) of a portion of the catheter (e.g., tip, portion of tubing, etc.) or the catheter tubing in its entirety within the body of a patient (hereinafter, described as the "physical state of the catheter"). Herein, the outer core fibers are spatially separated along the circumference of the tubing wall and each outer core fiber is configured to separately return light of different spectral widths (e.g., specific light wavelength or a range of light wavelengths) reflected from the distributed array of sensors fabricated in each of the core fibers. A comparison of detected shifts in wavelength of the reflected light from the outer core fibers to wavelength shifts of the reflected light from the center core fiber, operating as a reference, may be used to determine the physical state of the catheter.

More specifically, during vasculature insertion, the clinician may rely on the console to visualize a current physical state of the catheter (e.g., shape, orientation, etc.) to avoid potential path deviations that would be caused by changes in catheter orientation (e.g., changes in angular orientation of the integrated tubing, etc.). As the outer core fibers reside within the second plurality of micro-lumens laterally aligned at different locations along the circumference of the tubing wall, changes in angular orientation (bending) of the integrated tubing of the catheter imposes different types (e.g., compression or tension) and degrees of strain on each of the outer core fibers as well as the center core fiber. The different types and/or degree of strain may cause the sensors of the core fibers to apply different wavelength shifts, which can be measured to extrapolate the physical state of the catheter.

These and other features of embodiments of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of embodiments of the invention as set forth hereinafter.

Reference will now be made to figures wherein like structures will be provided with like reference designations. It is understood that the drawings are diagrammatic and schematic representations of exemplary embodiments of the invention, and are neither limiting nor necessarily drawn to scale.

Regarding terms used herein, it should be understood the terms are for the purpose of describing some particular embodiments, and the terms do not limit the scope of the concepts provided herein. Ordinal numbers (e.g., first, second, third, etc.) are generally used to distinguish or identify different components or operations, and do not supply a serial or numerical limitation. For example, "first," "second," and "third" components or operations need not necessarily appear in that order, and the particular embodiments including such components or operations need not necessarily be limited to the three components or operations. Similarly, labels such as "left," "right," "top," "bottom," "front," "back," and the like are used for convenience and are not intended to imply, for example, any particular fixed location, orientation, or direction.

In the following description, the terms "or" and "and/or" as used herein are to be interpreted as inclusive or meaning any one or any combination. As an example, "A, B or C" or "A, B and/or C" mean "any of the following: A; B; C; A and B; A and C; B and C; A, B and C. " An exception to this definition will occur only when a combination of elements, components, functions, steps or acts are in some way inherently mutually exclusive.

The term "logic" is representative of hardware and/or software that is configured to perform one or more functions. As hardware, logic may include circuitry having data processing and/or storage functionality. Examples of such circuitry may include, but are not limited or restricted to a processor, a programmable gate array, a microcontroller, an application specific integrated circuit, combinatorial circuitry, or the like. Alternatively, or in combination with the hardware circuitry described above, the logic may be software in the form of one or more software modules, which may be configured to operate as its counterpart circuitry. The software modules may include, for example, an executable application, a daemon application, an application programming interface (API), a subroutine, a function, a procedure, a routine, source code, or even one or more instructions. The software module(s) may be stored in any type of a suitable non-transitory storage medium, such as a programmable circuit, a semiconductor memory, non-persistent storage such as volatile memory (e.g., any type of random access memory "RAM"), persistent storage such as non-volatile memory (e.g., read-only memory "ROM", power-backed RAM, flash memory, phase-change memory, etc.), a solid-state drive, hard disk drive, an optical disc drive, or a portable memory device.

For clarity, it is to be understood that the word "proximal" refers to a direction relatively closer to a clinician using the device to be described herein, while the word "distal" refers to a direction relatively further from the clinician. Herein, the "proximal portion" of an integrated tubing of a catheter disclosed herein, for example, includes a portion of the catheter tubing intended to be near a clinician when the catheter is used on the patient. Likewise, a "proximal end" of the catheter tubing, for example, includes an end intended to be near the clinician when the catheter is in use. The proximal portion of the catheter tubing may include the proximal end of the catheter tubing; however, proximal portion of the catheter tubing does not need to include the proximal end of the catheter tubing.

Similarly, a "distal portion" of the integrated tubing of the catheter includes a portion of the catheter tubing intended to be near or in a patient when the catheter is used on the patient. Likewise, a "distal end" of the catheter tubing includes an end of the catheter tubing intended to be near or in the patient when the catheter is in use. The distal portion of the catheter tubing can include the distal end of the catheter tubing; however, the distal portion of the catheter tubing does not need include the distal end of the catheter tubing. Also, the words "including," "has," and "having," as used herein, including the claims, shall have the same meaning as the word "comprising.

Referring to <FIG>, an exemplary embodiment of a medical instrument monitoring system <NUM> is shown. Herein, the medical instrument monitoring system <NUM> features a console <NUM> and a medical instrument <NUM> communicatively coupled to the console <NUM>. For this embodiment, the medical instrument <NUM> corresponds to a catheter, which features an integrated tubing <NUM> with two or more lumen <NUM> extending between a proximal end and a distal end <NUM> of the integrated tubing <NUM>. The integrated tubing <NUM> (sometimes referred to as "catheter tubing") is in communication with one or more extension legs <NUM> via a bifurcation hub <NUM>. An optical-based catheter connector <NUM> may be included on an proximal end of at least one of the extension legs <NUM> to enable the catheter <NUM> to operably connect to the console <NUM> via an interconnect <NUM> or another suitable component. Herein, the interconnect <NUM> may include a connector <NUM> that, when coupled to the optical-based catheter connector <NUM>, establishes optical connectivity between one or more optical fibers <NUM> (hereinafter, "optical fiber(s)") included as part of the interconnect <NUM> and core fibers <NUM> deployed within the catheter <NUM> and integrated into the tubing <NUM>. Alternatively, a different combination of connectors, including one or more adapters, may be used to optically connect the optical fiber(s) <NUM> to the core fibers <NUM> within the catheter <NUM>.

An exemplary implementation of the console <NUM> includes a processor <NUM>, a memory <NUM>, a display <NUM> and optical logic <NUM>, although it is appreciated that the console <NUM> can take one of a variety of forms. The processor <NUM>, with access to the memory <NUM> (e.g., non-volatile memory), is included to control functionality of the console <NUM> during operation. As shown, the display <NUM> may be a liquid crystal diode (LCD) display integrated into the console <NUM> and employed as a user interface to display information to the clinician, especially during a catheter placement procedure (e.g., cardiac catheterization). In another embodiment, the display <NUM> may be separate from the console <NUM>. For both of these embodiments, the content rendered by the display <NUM> may constitute a two-dimensional (<NUM>-D) or three-dimensional (<NUM>-D) representation of the physical state of the catheter <NUM> (e.g., length, shape, form, and/or orientation of the catheter <NUM> or a portion of the catheter <NUM>) computed from characteristics of reflected light signals <NUM> returned to the console <NUM>. According to one embodiment of the disclosure, the reflected light signals <NUM> may pertain to various discrete portions (e.g., specific spectral widths) of broadband incident light <NUM> transmitted from and sourced by the optical logic <NUM>, as described below.

Referring still to <FIG>, the optical logic <NUM> is configured to support graphical rendering of the catheter <NUM>, most notably the integrated tubing <NUM> of the catheter <NUM>, based on characteristics of the reflected light signals <NUM> received from the catheter <NUM>. The characteristics may include shifts in wavelength caused by strain on certain regions of the core fibers <NUM> integrated within (or along) a wall of the integrated tubing <NUM>, which may be used to determine (through computation or extrapolation of the wavelength shifts) the physical state of the catheter <NUM>, notably its integrated tubing <NUM> or a portion of the integrated tubing <NUM> such as a tip or distal end of the tubing <NUM> to read fluctuations (real-time movement) of the tip (or distal end).

More specifically, the optical logic <NUM> includes a light source <NUM>. The light source <NUM> is configured to transmit the broadband incident light <NUM> for propagation over the optical fiber(s) <NUM> included in the interconnect <NUM>, which are optically connected to multiple core fibers <NUM> within the catheter tubing <NUM>. In one embodiment, the light source <NUM> is a tunable swept laser, although other suitable light source can also be employed in addition to a laser, including semi-coherent light sources, LED light sources, etc..

According to one embodiment of the disclosure, the optical logic <NUM> further includes an optical receiver <NUM> (e.g., a photodetector such as a positive-intrinsic-negative "PIN" photodiode, avalanche photodiode, etc.). Herein, the optical receiver <NUM> is configured to: (i) receive returned optical signals, namely reflected light signals <NUM> received from optical fiber-based reflective gratings (sensors) fabricated within each of the core fibers <NUM> deployed within the catheter <NUM> (see <FIG>), and (ii) translate the reflected light signals <NUM> into reflection data <NUM>, namely data in the form of electrical signals representative of the reflected light signals including wavelength shifts caused by strain. The reflected light signals <NUM> associated with different spectral widths include reflected light signals <NUM> provided from sensors positioned in the center core fiber (reference) of the catheter <NUM> and reflected light signals <NUM> provided from sensors positioned in the outer core fibers of the catheter <NUM>, as described below.

As shown, both the light source <NUM> and the optical receiver <NUM> are operably connected to the processor <NUM>, which governs their operation. Also, the optical receiver <NUM> is operably coupled to provide the reflection data <NUM> to the memory <NUM> for storage and processing by reflection data classification logic <NUM>. The reflection data classification logic <NUM> may be configured to (i) identify which core fibers pertain to which of the received reflection data <NUM> and (ii) segregate the reflection data <NUM> provided from reflected light signals <NUM> pertaining to similar regions of the catheter <NUM> and/or spectral widths into analysis groups. The reflection data for each analysis group is made available to shape sensing logic <NUM> for analytics.

According to one embodiment of the disclosure, the shape sensing logic <NUM> is configured to compare wavelength shifts measured by sensors deployed in each outer core fiber at the same measurement region of the catheter (or same spectral width) to the wavelength shift at the center core fiber positioned along central axis and operating as a neutral axis of bending. From these analytics, the shape sensing logic <NUM> may determine the shape the core fibers have taken in <NUM>-D space and may further determine the current physical state of the catheter <NUM> in <NUM>-D space for rendering on the display <NUM>.

According to one embodiment of the disclosure, the shape sensing logic <NUM> may generate a rendering of the current physical state of the catheter <NUM>, especially the integrated tubing <NUM>, based on heuristics or run-time analytics. For example, the shape sensing logic <NUM> may be configured in accordance with machine-learning techniques to access a data store (library) with pre-stored data (e.g., images, etc.) pertaining to different regions of the catheter <NUM> in which the core fibers <NUM> experienced similar or identical wavelength shifts. From the pre-stored data, the current physical state of the catheter <NUM> may be rendered. Alternatively, as another example, the shape sensing logic <NUM> may be configured to determine, during run-time, changes in the physical state of each region of the catheter <NUM>, notably the tubing <NUM>, based on at least (i) resultant wavelength shifts experienced by the core fibers <NUM> and (ii) the relationship of these wavelength shifts generated by sensors positioned along different outer core fibers at the same cross-sectional region of the catheter <NUM> to the wavelength shift generated by a sensor of the center core fiber at the same cross-sectional region. It is contemplated that other processes and procedures may be performed to utilize the wavelength shifts as measured by sensors along each of the core fibers <NUM> to render appropriate changes in the physical state of the catheter <NUM>.

Referring now to <FIG>, an embodiment of the catheter <NUM> illustrating its insertion into a vasculature of a patient <NUM> through a skin insertion site <NUM> is shown. Herein, the catheter <NUM> generally includes the integrated tubing <NUM> with a proximal portion <NUM> that generally remains exterior to the patient <NUM> and a distal portion <NUM> that generally resides within the patient vasculature after placement is complete. The (integrated) catheter tubing <NUM> may be advanced to a desired position within the patient vasculature such as a distal end (or tip) <NUM> of the catheter tubing <NUM> is proximate the patient's heart, such as in the lower one-third (<NUM>/<NUM>) portion of the Superior Vena Cava ("SVC") for example. For this embodiment, various instruments may be placed at the distal end <NUM> of the catheter tubing <NUM> to measure pressure of blood in a certain heart chamber and in the blood vessels, view an interior of blood vessels, or the like.

During advancement through a patient vasculature, the catheter tubing <NUM> receives broadband incident light <NUM> from the console <NUM> via optical fiber(s) <NUM> within the interconnect <NUM>, where the incident light <NUM> propagates to the core fibers <NUM> within the catheter tubing <NUM>. According to one embodiment of the disclosure, the connector <NUM> of the interconnect <NUM> terminating the optical fiber(s) <NUM> may be coupled to the optical-based catheter connector <NUM>, which may be configured to terminate the core fibers <NUM> deployed within the catheter <NUM>. Such coupling optically connects the core fibers <NUM> of the catheter <NUM> with the optical fiber(s) <NUM> within the interconnect <NUM>. The optical connectivity is needed to propagate the incident light <NUM> to the core fibers <NUM> and return the reflected light signals <NUM> to the optical logic <NUM> within the console <NUM> over the interconnect <NUM>. As described below in detail, the physical state of the catheter <NUM> may be ascertained based on analytics of the wavelength shifts of the reflected light signals <NUM>.

Referring to <FIG>, an illustrative embodiment of the catheter <NUM> of <FIG> is shown. Herein, the catheter <NUM> includes the integrated tubing <NUM> and at least one septum <NUM> extending across a diameter "d" of the tubing <NUM> and positioned at distal end <NUM> of the catheter tubing <NUM>. The septum(s) <NUM> assist in forming multiple lumina <NUM> within the tubing <NUM> between an inner surface <NUM> of a wall <NUM> forming the tubing <NUM> and surfaces of the septum <NUM> extending longitudinally from the distal end <NUM> towards the bifurcation hub <NUM> of the catheter <NUM>. Sized with a diameter less than any of the multiple lumina <NUM> (e.g., lumen <NUM> and <NUM> of <FIG>), a plurality of micro-lumens <NUM><NUM>-<NUM>N (N≥<NUM>) may be collectively formed within the septum <NUM> and along a circumference of the catheter tubing <NUM>, such as formed in the wall <NUM> of the integrated tubing <NUM> itself (e.g., one or more micro-lumens, such as micro-lumens <NUM><NUM>-<NUM><NUM>, fabricated to reside between the inner surface <NUM> and an outer surface <NUM> of the wall <NUM>) or as a longitudinal bead formed on the inner surface <NUM> or outer surface <NUM> of the wall <NUM>. The micro-lumens <NUM><NUM>-<NUM>N are configured to retain a corresponding plurality of core fibers <NUM><NUM>-<NUM>N, as shown in <FIG>.

More specifically, as show in <FIG>, the catheter <NUM> includes at least one septum (e.g., septum <NUM>) spanning across the diameter "d" of the tubing <NUM> and continuing longitudinally to subdivide an opening <NUM> formed by the tubing <NUM> to produce the lumina <NUM>. The septum <NUM> may be fabricated as part of the catheter <NUM> during extrusion or may be fabricated as a separate component and inserted into the tubing of the catheter during manufacture. As an alternative embodiment, the catheter <NUM> may be configured where the septum <NUM> does not divide the opening <NUM>, as portion of the wall <NUM> may protrude into the cross section space occupied by the distal end of the catheter (area at the opening <NUM>) or portion of the wall <NUM> may protrude into the cross section space occupied by the distal end of the catheter (area at the opening <NUM>) in which a center micro-lumen is formed within the protruding portion of the wall <NUM> to maintain one or more core fibers.

As described below, the septum <NUM> is fabricated with a first micro-lumen <NUM><NUM> of the above-identified plurality of micro-lumens <NUM><NUM>-<NUM>N, where the first micro-lumen <NUM><NUM> is coaxial with a central axis <NUM> of the integrated tubing <NUM> by being positioned within a medial portion of the septum <NUM> at or near a cross-sectional center <NUM> of the integrated tubing <NUM>. The cross-sectional center <NUM> is the center location from a perspective facing a cross-sectional area of the distal end <NUM> of the integrated tubing <NUM>. Herein, the first micro-lumen <NUM><NUM> is configured to retain a single core fiber <NUM><NUM> (hereinafter, "center core fiber"). A second plurality of micro-lumens <NUM><NUM>-<NUM>N, which are a subset of the plurality of micro-lumens <NUM><NUM>-<NUM>N, are positioned along a circumference <NUM> of the integrated tubing <NUM>. The micro-lumens <NUM><NUM>-<NUM>N retain corresponding core fibers <NUM><NUM>-<NUM>N (hereinafter, "outer core fibers"). According to one embodiment of the disclosure, as shown, one or more of the outer core fibers (e.g., the second plurality of core fibers <NUM><NUM>-<NUM>N) are located at different quadrants along the circumference <NUM> of the integrated tubing <NUM> as shown in <FIG>.

As shown in <FIG>, each core fiber <NUM><NUM> (<NUM>≤i≤N) includes an array of sensors <NUM>il-380iM (<NUM>≤i≤N; M≥<NUM>) spatially distributed along its length between at least a proximal and distal ends of the catheter tubing <NUM>. Each sensor <NUM>i1-<NUM>iM may be positioned at different measurement regions <NUM><NUM>-<NUM>M distributed along a prescribed length of the core fiber <NUM>i in efforts to sense strain occurring at these fiber regions <NUM><NUM>-<NUM>M, especially during advancement of the catheter <NUM> within the patient vasculature. The distribution length may be static or variable.

More specifically, each of the sensors <NUM>i1-<NUM>iM (i=<NUM>. N as shown in <FIG>) is configured to reflect light at a different spectral width (e.g., specific wavelength or specific wavelength range), where neighboring sensors (e.g., sensors <NUM>i1-<NUM>i2, sensors <NUM>i2-<NUM>i3, etc.) may be arranged to reflect light with non-overlapping spectral widths. However, in response to the core fiber <NUM><NUM> (i=<NUM>) experiencing strain at any of the fiber regions <NUM><NUM>-<NUM>M (e.g., fiber regions <NUM><NUM>), the sensor <NUM><NUM> also experiences strain that causes the sensor <NUM><NUM> to alters characteristics of the reflected light signal in order to represent the sensed strain. As a result, collectively, the reflected light signals returned by sensors <NUM>i1-<NUM><NUM>iM along each core fiber <NUM><NUM>-<NUM>N may be used by the console <NUM> to recover reflection data for use in determining the current <NUM>-D shape of the core fibers <NUM><NUM>-<NUM>N. From the current <NUM>-D shape of the core fibers <NUM><NUM>-<NUM>N, the current <NUM>-D shape of the catheter <NUM> may be determined for subsequent rendering.

For ease of discussion, the operations of a selected core fiber <NUM><NUM> and the operations of the sensors <NUM><NUM>-<NUM><NUM> deployed on the core fiber <NUM><NUM> shall be discussed. The other core fibers <NUM><NUM>, <NUM><NUM>. and/or <NUM>N may be configured in a similar or identical manner.

According to one embodiment of the disclosure, each sensor <NUM><NUM>-<NUM><NUM> may be configured as a fiber Bragg grating (FBG), namely an intrinsic sensor corresponding to a permanent, periodic refractive index change inscribed into the core fiber <NUM><NUM>. Stated differently, each sensor <NUM><NUM>. and <NUM><NUM> operates as a light reflective mirror for a different, specific spectral width. As a result, as broadband incident light <NUM> is supplied by an optical light source and propagates through the core fiber <NUM><NUM>, upon reaching a first sensor <NUM><NUM> positioned at a first region <NUM><NUM> of the core fiber <NUM><NUM>, light <NUM> of a spectral width selected for the first sensor <NUM><NUM> is reflected back to the optical receiver <NUM> within the console <NUM> (see <FIG>). Based on the type and degree of strain (e.g., compression or tension) sensed on the core fiber <NUM><NUM> at the first region <NUM><NUM>, the first sensor <NUM><NUM> alters characteristics of reflected light signal <NUM>. The altered characteristics may correspond to the reflected light signal <NUM> experiencing a wavelength shift that is correlated to the type of strain (e.g., compression or tension) and degree of strain. The remaining spectrum <NUM> of the incident light <NUM> continues propagation through the core fiber <NUM><NUM> toward the distal end <NUM> of the catheter tubing <NUM>. The remaining spectrum <NUM> of the incident light <NUM> may encounter another sensor <NUM><NUM>. or <NUM><NUM>, where each of these sensors <NUM><NUM>. or <NUM><NUM> is fabricated to reflect light with different specific spectral widths. Similarly, reflected light signals of the different spectral widths are returned from the core fiber <NUM><NUM>.

As an illustrative example, where a particular region of the catheter <NUM> is undergoing a change in angular orientation (e.g., catheter tubing <NUM> is bending), a portion of the second outer core fiber <NUM><NUM>, which is located at the first measurement region <NUM><NUM>, may experience tension (positive strain; force applied to increase length). As a result, upon receipt of the incident light <NUM>, the sensor <NUM><NUM> located at the first region <NUM><NUM> would return reflected light <NUM> with an elevated attenuation (e.g., frequency of the reflected light signal <NUM> is higher than the frequency of the incident light <NUM>). Therefore, the tension applied to the second outer core fiber <NUM><NUM> causes a shift (increase) in the reflected light wavelength and amount of wavelength shift is correlated to the amount of tension applied to the second outer core fiber <NUM><NUM>.

Similarly, as the particular region of the catheter is undergoing the change in angular orientation, a portion of a fourth outer core fiber <NUM><NUM> also located in the first measurement region <NUM><NUM>, may experience compression (negative strain; force applied to shorten length). As a result, upon receipt of the incident light <NUM>, the sensor <NUM><NUM> located at the first region <NUM><NUM> would return reflected light <NUM> with a decreased attenuation (e.g., frequency of the reflected light signal <NUM> is lower than the frequency of the incident light <NUM>). Therefore, the tension applied to the fourth outer core fiber <NUM><NUM> causes a shift (decrease) in the reflected light wavelength and amount of wavelength shift conducted on the reflected light signal <NUM> is correlated to the amount of compression applied to the fourth outer core fiber <NUM><NUM>.

In view of the foregoing, different strains effect the plurality of core fibers <NUM><NUM>-<NUM>N differently, given their longitudinal position within spatially separated micro-lumens <NUM><NUM>-<NUM>N. The degrees of wavelength shift encountered by different sensors along a distributed array of sensor for each core fiber <NUM><NUM>-<NUM>N may collectively identify the type (e.g., compression, tension) and amount of strain imposed on each region of the plurality of core fibers. Hence, multiple reflected light signals corresponding to the different spectral widths, which are produced by the distributed array of sensors positioned at selected regions over a length of the core fiber, may be provide <NUM>-D shape sensing information for the shape sensing logic <NUM> within the console <NUM> to determine how each of the monitored regions of the catheter <NUM> is being manipulated. As a result, the current physical state of the catheter <NUM> may be determined and rendered in three-dimension (<NUM>-D) on the display <NUM> of the console <NUM> based on analytics of the wavelength shifts provided from the core fibers, as described above.

Referring now to <FIG>, a perspective view of a first illustrative embodiment of the integrated tubing <NUM> of the catheter <NUM> of <FIG> is shown. Herein, the catheter <NUM> includes the integrated tubing <NUM>, the diametrically disposed septum <NUM>, and the plurality of micro-lumens <NUM><NUM>-<NUM><NUM> which, for this embodiment, are fabricated to reside within the wall <NUM> of the integrated tubing <NUM> and within the septum <NUM>. In particular, the septum <NUM> separates a single lumen, formed by the inner surface <NUM> of the wall <NUM> of the tubing <NUM>, into multiple lumen, namely two lumen <NUM> and <NUM> as shown. Herein, the first lumen <NUM> is formed between a first arc-shaped portion <NUM> of the inner surface <NUM> of the wall <NUM> forming the tubing <NUM> and a first outer surfaces <NUM> of the septum <NUM> extending longitudinally within the tubing <NUM>. The second lumen <NUM> is formed between a second arc-shaped portion <NUM> of the inner surface <NUM> of the wall <NUM> forming the tubing <NUM> and a second outer surfaces <NUM> of the septum <NUM>.

According to one embodiment of the disclosure, the two lumen <NUM> and <NUM> have approximately the same volume. However, the septum <NUM> need not separate the tubing <NUM> into two equal lumen. For example, instead of the septum <NUM> extending vertically (<NUM> o'clock to <NUM> o'clock) from a front-facing, cross-sectional perspective of the tubing <NUM>, the septum <NUM> could extend horizontally (<NUM> o'clock to <NUM> o'clock), diagonally (<NUM> o'clock to <NUM> o'clock; <NUM> o'clock to <NUM> o'clock) or angularly (<NUM> o'clock to <NUM> o'clock). In the later configuration, each of the lumens <NUM> and <NUM> of the tubing <NUM> would have a different volume.

With respect to the plurality of micro-lumens <NUM><NUM>-<NUM><NUM>, the first micro-lumen <NUM><NUM> is fabricated within the septum <NUM> at or near the cross-sectional center <NUM> of the tubing <NUM>. For this embodiment, three micro-lumens <NUM><NUM>-<NUM><NUM> are fabricated to reside within the wall <NUM> of the tubing <NUM>. In particular, a second micro-lumen <NUM><NUM> is fabricated within the wall <NUM> of the tubing <NUM>, namely between the inner surface <NUM> and outer surface <NUM> of the first arc-shaped portion <NUM> of the wall <NUM>. Similarly, the third micro-lumen <NUM><NUM> is also fabricated within the wall <NUM> of the tubing <NUM>, namely between the inner and outer surfaces <NUM>/<NUM> of the second arc-shaped portion <NUM> of the wall <NUM>. The fourth micro-lumen <NUM><NUM> is also fabricated within the inner and outer surfaces <NUM>/<NUM> of the wall <NUM> that are aligned with the septum <NUM>.

According to one embodiment of the disclosure, as shown in <FIG>, the micro-lumens <NUM><NUM>-<NUM><NUM> are positioned in accordance with a "top-left" (<NUM> o'clock), "top-right" (<NUM> o'clock) and "bottom" (<NUM> o'clock) layout from a front-facing, cross-sectional perspective. Of course, the micro-lumens <NUM><NUM>-<NUM><NUM> may be positioned differently, provided that the micro-lumens <NUM><NUM>-<NUM><NUM> are spatially separated along the circumference <NUM> of the tubing <NUM> to ensure a more robust collection of reflected light signals from the outer core fibers <NUM><NUM>-<NUM><NUM> when installed. For example, two or more of micro-lumens (e.g., micro-lumens <NUM><NUM> and <NUM><NUM>) may be positioned at different quadrants along the circumference <NUM> of the catheter wall <NUM>.

Referring now to <FIG>, a perspective view of the first illustrative embodiment of the integrated tubing <NUM> of the catheter <NUM> of <FIG> is shown, with the core fibers <NUM><NUM>-<NUM><NUM> installed within the micro-lumens <NUM><NUM>-<NUM><NUM>. According to one embodiment of the disclosure, the second plurality of micro-lumens <NUM><NUM>-<NUM><NUM> are sized to retain corresponding outer core fibers <NUM><NUM>-<NUM><NUM>, where the diameter of each of the second plurality of micro-lumens <NUM><NUM>-<NUM><NUM> may be sized just larger than the diameters of the outer core fibers <NUM><NUM>-<NUM><NUM>. The size differences between a diameter of a single core fiber and a diameter of any of the micro-lumen <NUM><NUM>-<NUM><NUM> may range between <NUM> micrometers (µm) and <NUM>, for example. As a result, the cross-sectional areas of the outer core fibers <NUM><NUM>-<NUM><NUM> would be less than the cross-sectional areas of the corresponding micro-lumens <NUM><NUM>-<NUM><NUM>. A "larger" micro-lumen (e.g., micro-lumen <NUM><NUM>) may better isolate external strain being applied to the outer core fiber <NUM><NUM> from strain directly applied to the tubing <NUM> itself. Similarly, the first micro-lumen <NUM><NUM> may be sized to retain the center core fiber <NUM><NUM>, where the diameter of the first micro-lumen <NUM><NUM> may be sized just larger than the diameter of the center core fiber <NUM><NUM>.

As an alternative embodiment of the disclosure, one or more of the micro-lumens <NUM><NUM>-<NUM><NUM> may be sized with a diameter that exceeds the diameter of the corresponding one or more core fibers <NUM><NUM>-<NUM><NUM>. However, at least one of the micro-lumens <NUM><NUM>-<NUM><NUM> is sized to fixedly retain their corresponding core fiber (e.g., core fiber retained with no spacing between its lateral surface and the interior wall surface of its corresponding micro-lumen). As yet another alternative embodiment of the disclosure, all the micro-lumens <NUM><NUM>-<NUM><NUM> are sized with a diameter to fixedly retain the core fibers <NUM><NUM>-<NUM><NUM>.

Referring to <FIG>, a perspective view of second illustrative embodiment of the catheter <NUM> of <FIG> is shown. The catheter <NUM> includes the integrated tubing <NUM> and a diametrically disposed septum <NUM> along with a radially disposed septum <NUM> extending from a cross-sectional center <NUM> of the integrated tubing <NUM>. Each of the three lumens <NUM>, <NUM>, and <NUM> is further defined at least in part by the septum <NUM>. Each lumen of the two lumens <NUM> and <NUM> is even further defined at least in part by the septum <NUM>. As shown, the septum <NUM> separates the interior space within the tubing <NUM> into a first set of semi-circular lumens, including the first lumen <NUM>. The septum <NUM> further separates one of the first set of semi-circular lumens into lumens <NUM> and <NUM>. As a result, the second lumen <NUM> may be configured with approximately the same volume as the third lumen <NUM>, and the first lumen <NUM> may be configured with at least double the volume of the second and third lumen <NUM> and <NUM>, provided the longitudinal lengths of these lumen <NUM>, <NUM>, <NUM> are equivalent.

As further shown in <FIG>, the plurality of micro-lumens <NUM><NUM>-<NUM><NUM> are fabricated to be located within the wall <NUM> of the integrated tubing <NUM> and within the septum <NUM>. As similar to <FIG>, the first micro-lumen <NUM><NUM> is fabricated within a medial portion <NUM> of the septum <NUM> at or near the cross-sectional center <NUM> of the integrated tubing <NUM>. The three micro-lumens <NUM><NUM>-<NUM><NUM> are fabricated to reside within the wall <NUM> of the integrated tubing <NUM>. In particular, a second micro-lumen <NUM><NUM> is fabricated within the wall <NUM> of the tubing <NUM>, namely between the inner surface <NUM> and the outer surface <NUM> of the wall <NUM> defining the first lumen <NUM>. Similarly, the third micro-lumen <NUM><NUM> is also fabricated within the wall <NUM> of the tubing <NUM>, such as within another area of the wall <NUM> between its inner surface <NUM> and outer surface <NUM>. Extending in radial directions from the cross-sectional center <NUM>, the third micro-lumen <NUM><NUM> is displaced approximately ninety radial degrees (<NUM>°) or more from the second micro-lumen <NUM><NUM>. The fourth micro-lumen <NUM><NUM> may be fabricated within the inner surface <NUM> and the outer surface <NUM> of the wall <NUM>, where the fourth micro-lumen <NUM><NUM> is aligned with the septum <NUM>. Alternatively, the fourth micro-lumen <NUM><NUM> may be fabricated within septum <NUM> substantially closer to the inner surface <NUM> of the wall <NUM> than the cross-sectional center <NUM>.

According to this particular embodiment of the disclosure, the micro-lumens <NUM><NUM>-<NUM><NUM> are positioned in accordance with a "bottom-right" (<NUM> o'clock), "bottom-left" (<NUM> o'clock) and "top" (<NUM> o'clock) layout from a front-facing, cross-sectional perspective. Of course, the micro-lumens <NUM><NUM>-<NUM><NUM> may be positioned differently, provided that the micro-lumens <NUM><NUM>-<NUM><NUM> are spatially separated along the circumference <NUM> of the tubing <NUM> to ensure a more robust collection of reflected light signals from the outer core fibers <NUM><NUM>-<NUM><NUM> when installed. For example, as shown, at least two different micro-lumens (e.g., micro-lumens <NUM><NUM> and <NUM><NUM>) may be positioned at different quadrants along the circumference <NUM> of the catheter wall <NUM>.

Referring now to <FIG>, flowcharts of the method of operations conducted by components of the medical instrument monitoring system of <FIG> to achieve optic <NUM>-D shape sensing is shown. Herein, the catheter includes at least one septum spanning across a diameter of the tubing wall and continuing longitudinally to subdivide the tubing wall. The medial portion of the septum is fabricated with a first micro-lumen, where the first micro-lumen is coaxial with the central axis of the catheter tubing. The first micro-lumen is configured to retain a center core fiber. Two or more micro-lumen, other than the first micro-lumen, are positioned at different locations circumferentially spaced along the wall of the catheter tubing. For example, two or more of the second plurality of micro-lumens may be positioned at different quadrants along the circumference of the catheter wall.

Furthermore, each core fiber includes a plurality of sensors spatially distributed along its length between at least the proximal and distal ends of the catheter tubing. This array of sensors are distributed to position sensors at different regions of the core fiber to enable distributed measurements of strain throughout the entire length or a selected portion of the catheter tubing. These distributed measurements may be conveyed through reflected light of different spectral widths (e.g., specific wavelength or specific wavelength ranges) that undergoes certain wavelength shifts based on the type and degree of strain.

According to one embodiment of the disclosure, as shown in <FIG>, for each core fiber, broadband incident light is supplied to propagate through a particular core fiber (block <NUM>). Unless discharged, upon the incident light reaching a sensor of a distributed array of sensors measuring strain on a particular core fiber, light of a prescribed spectral width associated with the first sensor is to be reflected back to an optical receiver within a console (blocks <NUM>-<NUM>). Herein, the sensor alters characteristics of the reflected light signal to identify the type and degree of strain on the particular core fiber as measured by the first sensor (blocks <NUM>-<NUM>). According to one embodiment of the disclosure, the alteration in characteristics of the reflected light signal may signify a change (shift) in the wavelength of the reflected light signal from the wavelength of the incident light signal associated with the prescribed spectral width. The sensor returns the reflected light signal over the core fiber and the remaining spectrum of the incident light continues propagation through the core fiber toward a distal end of the catheter tubing (blocks <NUM>-<NUM>). The remaining spectrum of the incident light may encounters other sensors of the distributed array of sensors, where each of these sensors would operate as set forth in blocks <NUM>-<NUM> until the last sensor of the distributed array of sensors returns the reflected light signal associated with its assigned spectral width and the remaining spectrum is discharged as illumination.

Referring now to <FIG>, during operation, multiple reflected light signals are returned to the console from each of the plurality of core fibers residing within the corresponding plurality of micro-lumens formed within the catheter. In particular, the optical receiver receives reflected light signals from the distributed arrays of sensors located on the center core fiber and the outer core fibers and translates the reflected light signals into reflection data, namely electrical signals representative of the reflected light signals including wavelength shifts caused by strain (blocks <NUM>-<NUM>). The reflection data classification logic is configured to identify which core fibers pertain to which reflection data and segregate reflection data provided from reflected light signals pertaining to a particular measurement region (or similar spectral width) into analysis groups (block <NUM>-<NUM>).

Each analysis group of reflection data is provided to shape sensing logic for analytics (block <NUM>). Herein, the shape sensing logic compares wavelength shifts at each outer core fiber with the wavelength shift at the center core fiber positioned along central axis and operating as a neutral axis of bending (block <NUM>). From this analytics, on all analytic groups (e.g., reflected light signals from sensors in all or most of the core fibers), the shape sensing logic may determine the shape the core fibers have taken in three-dimensional space, from which the shape sensing logic can determine the current physical state of the catheter in three-dimension space (blocks <NUM>-<NUM>).

Claim 1:
A catheter (<NUM>), comprising:
an elongated tubing including an opening (<NUM>) at a distal end of the tubing, the tubing being formed by an axial wall (<NUM>) defining a lumen extending between a proximal end of the tubing to the distal end of the tubing;
a septum (<NUM>) positioned across the opening of the tubing;
a first micro-lumen (<NUM><NUM>) formed in the septum;
a plurality of micro-lumens (<NUM><NUM>-<NUM>N) formed along a circumference of the wall forming the tubing; and further comprising:
a first core fiber (<NUM><NUM>) residing within the first micro-lumen; and
a plurality of core fibers (<NUM><NUM>-<NUM>N) each residing within a different micro-lumen of the plurality of micro-lumens,
wherein a plurality of sensors (<NUM>i1-<NUM>iM) are distributed along a longitudinal length of both the first core fiber and each of the plurality of core fibers and each sensor of the plurality of sensors being configured to (i) reflect a light signal of a different spectral width based on received incident light and (ii) change a characteristic of the reflected light signal for use in determining a physical state of the catheter.