Impedance-based navigation of sheath

Abstract

The subject matter of the invention is impedance-based navigation of sheaths. A sheath having a conductive region that provides a low impedance path through a sheath wall is shown. When the impedance-based tracking electrode is adjacent the conductive region, the conductive region is configured to conduct electrical current between the impedance-based tracking electrode of the endoluminal catheter and the body patch electrode of the impedance-based tracking system. The impedance-based tracking system is configured to determine a location of the conductive region based on a ratio of currents at the body patch electrodes, and thereby determine a location of the distal end of the sheath. The conductive region may include a flushing hole such that brine acts as an electrical conduit for the conductive region. In addition to or alternatively, the conductive region may include a conductive material configured to act as an electrical conduit through the sheath wall.

Description

Background Art

[0001] In many medical procedures, it is necessary to track the position of internal objects such as sensors, tubes, catheters, dispensing devices, and implants. Well-established, highly accurate systems for determining the position of internal objects have been developed based on magnetic field sensing. These systems utilize sensors attached to internal objects to measure the relative strength of externally generated magnetic fields and derive the position of the objects from these measurements. The details of magnetic-based position sensing technology are described in U.S. Patents 5,391,199, 5,443,489, 5,558,091, 6,172,499, 6,239,724, 6,332,089, 6,484,118, 6,618,612, 6,690,963, 6,788,967, 6,892,091, each of which is incorporated herein by reference.

[0002] Position sensing systems that utilize impedance-based measurements may also have been developed. In such systems, the impedance between electrodes attached to an object in the body and electrodes placed on the body surface is measured. The system then derives the position of the object in the body from the impedance measurements. Details of impedance-based position tracking techniques are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182, each of which is incorporated herein by reference and is attached in the appendix to this document.

[0003] Areas of cardiac tissue may be mapped by catheters to identify abnormal electrical signals. Cardiac tissue may be ablated to interrupt abnormal electrical signals. Electrophysiological mapping may include using sensing electrodes on a catheter configured to monitor electrical signals within the cardiovascular system to precisely determine the location of abnormal conductive tissue sites that cause arrhythmias. An example of an EP mapping system is described in U.S. Patent No. 5,738,096, which is incorporated herein by reference. Examples of EP mapping catheters are described in U.S. Patent No. 9,907,480, U.S. Patent Publication No. 2018 / 0036078, and U.S. Patent Publication No. 2018 / 0056038, each of which is incorporated herein by reference.

[0004] In addition to using EP mapping, some catheter ablation procedures may also be performed using an image-guided surgery (IGS) system. An IGS system may enable a physician to visually track the position of a catheter within a patient relative to an image of the patient's anatomy in real time. Some systems may provide a combination of EP mapping and IGS functionality, including the EP-guided Surgery System from Biosense Webster, Inc. of Irvine, Calif. system. Summary of the invention

[0005] Provided herein is a sheath that may have radial perforations in the sheath wall approximately 1 centimeter (cm) to 3 cm from the distal end of the sheath. The perforations may be large enough to allow saline to be perfused during sheath flushing. The perforations may extend approximately 1 millimeter (mm) to 2 mm along the length of the sheath. The sheath is configured such that the perforations act as conductive conduits to an impedance-based tracking electrode of a catheter positioned within the lumen of the sheath. When the impedance-based tracking electrode is positioned adjacent to or near the perforation. The impedance-based tracking electrode may be positioned on the shaft of the catheter. For example, the impedance-based tracking electrode may include an inferior vena cava (IVC) electrode, such as the Biosense Webster The most proximal electrode of the lesion catheter of the SF. When the impedance-based tracking electrode is adjacent to or close to the perforation, the current input from the catheter electrode will be mainly conducted through the perforation. The control unit of the impedance-based tracking system can calculate the position of the perforation of the sheath based on the current ratio between the impedance-based tracking electrode and the body patch (e.g., six body patches). This calculation allows the sheath itself to be visualized, rather than only the impedance-based tracking electrode visualization that travels through the sheath. Alternatively, instead of the perforation, a small band of conductive material can be placed on the sheath to allow current to pass through the sheath wall. The conductive material can be polymer or metal in nature and constitute the entire cross-section of the sheath in this area, and / or it can include conductive fibers or rivets (polymer or metal) that act as through-channels for the ACL current.

[0006] An exemplary guide sheath may include a tubular shaft extending along a longitudinal axis between a proximal end and a distal end. The tubular shaft may have a lumen extending through the tubular shaft and a tubular wall surrounding the lumen. The predetermined tubular wall region may be configured to provide a conductive path through the tubular wall of the tubular shaft. The predetermined tubular wall region may be disposed proximate to the distal end of the tubular shaft.

[0007] An exemplary impedance-based tracking system may include an introducer sheath, a medical probe, a plurality of body patch electrodes, and a control unit. The introducer sheath may include a first tubular shaft and a predetermined tubular wall region, the first tubular shaft having a lumen running through the first tubular shaft, the predetermined tubular wall region being disposed near the distal end of the first tubular shaft. The predetermined tubular wall region may be configured to provide a conductive path through the predetermined tubular wall region. The medical probe may include a second tubular shaft configured to translate through the lumen of the first tubular shaft. The medical probe may also include a tracking electrode coupled to the second tubular shaft. The plurality of body patch electrodes may be configured to contact the patient's skin. The control unit may be configured to determine the position of the predetermined tubular wall region based at least in part on an electrical signal between the tracking electrode and the plurality of body patch electrodes.

[0008] An exemplary method of impedance tracking of an introducer sheath within a patient may include the following steps performed in a variety of orders and with interleaved steps as understood by a person skilled in the relevant art. The method may include passing a current signal between a probe electrode of a medical probe and a plurality of body patch electrodes, the probe electrode being disposed within a lumen of an introducer sheath within the patient, and the plurality of body patch electrodes being in contact with the patient's skin. The method may include determining a position of a distal portion of the introducer sheath based at least in part on the current signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Although claims are provided after the specification which particularly point out and distinctly claim the subject matter described herein, it is believed that the subject matter will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals represent the same elements. The accompanying drawings depict one or more specific implementations of the present device by way of example only and not by way of limitation.

[0010] Figure 1 is a diagram of an example catheter-based electrophysiological mapping and ablation system.

[0011] Figure 2 is an illustration of an exemplary sheath and catheter.

[0012] Figure 3A is an illustration of the distal portion of the sheath.

[0013] Figure 3B is an illustration of the distal portion of the catheter.

[0014] Figure 4A is an illustration of an impedance-based tracking system in which the impedance-based tracking electrodes of the catheter are not adjacent to the conductive regions of the sheath.

[0015] Figure 4B is an illustration of an impedance-based tracking system in which an impedance-based tracking electrode of a catheter is adjacent to a conductive region.

[0016] Figure 5 is an illustration of a distal portion of an exemplary sheath.

[0017] Fig. 6A , Figure 6B , Figure 6C and Fig.6D Yes Figure 5 A cross-sectional view of a distal portion of an exemplary sheath is shown illustrating an exemplary configuration of a predetermined tubular wall region configured to provide an electrically conductive path through the tubular wall.

[0018] Figure 7 is an illustration of a flow chart of a method of impedance tracking an introducer sheath within a patient. DETAILED DESCRIPTION

[0019] The following specific embodiments should be read in conjunction with the accompanying drawings, wherein the same elements are labeled the same in different drawings. The accompanying drawings (not necessarily drawn to scale) depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention by way of example and not by way of limitation. This description will clearly enable those skilled in the art to prepare and use the invention, and describes several embodiments, adaptations, variations, alternative forms and uses of the invention, including the best modes currently believed to be implemented in the invention.

[0020] As used herein, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows a part or a collection of components to achieve its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of ±10% of the value of the recited value, for example, "about 90%" may refer to a range of values ​​from 81% to 99%.

[0021] In addition, as used herein, the terms "patient", "recipient", "user" and "subject" refer to any human or animal subject, and are not intended to limit the systems or methods to human use, but the use of the subject invention in human patients represents a preferred embodiment. Likewise, the term "proximal" refers to a position closer to an operator, while "distal" refers to a position farther from an operator or physician.

[0022] As used herein, the terms "tubular" and "tube" should be understood broadly and are not limited to structures that are right cylindrical or have a completely circular cross section or a uniform cross section over their entire length. For example, a tubular structure or system is typically illustrated as a substantially right cylindrical structure. However, without departing from the scope of the present invention, a tubular structure or system may have a tapered or curved outer surface. A tubular structure or system or tube may have a hollow lumen, a solid core, or a combination thereof.

[0023] As used herein, the terms "sheath" and "introducer sheath" refer to an elongated intravascular device having a hollow tubular shaft that is configured to deliver one or more medical probes to a treatment site in a patient's body. The size of the sheath or introducer sheath is based on the inner diameter of the lumen of the hollow tubular shaft (e.g., measured in French). The sheath or introducer sheath may or may not be steerable.

[0024] As used herein, the term "catheter" refers to an elongated intravascular device that can be configured as a therapeutic and / or diagnostic medical probe. The size of the catheter is determined based on the outer diameter of the elongated tubular body (e.g., measured in French units). The catheter can be delivered by a compatible sheath having a size compatible with the catheter size.

[0025] Alternative device and system features and alternative method steps are presented in the example embodiments herein. As will be understood by those skilled in the relevant art and as explicitly stated herein, each given example embodiment presented herein may be modified to include features and / or method steps presented with different example embodiments herein, where such features and / or steps are compatible with the given example. Such modifications and variations are intended to be included within the scope of the claims.

[0026] Figure 1 is a diagram of an example catheter-based electrophysiological mapping and ablation system 10. The system 10 includes a plurality of catheters that are inserted percutaneously through the patient's vascular system into a chamber or vascular structure of a heart 12 by a physician 24. Typically, a guide sheath 40 is inserted into the left atrium or right atrium near a desired location in the heart 12. Thereafter, a plurality of catheters may be inserted into the guide sheath 40 to reach the desired location. The plurality of catheters may include a catheter dedicated to sensing intracardiac electrogram (IEGM) signals, a catheter dedicated to ablation, and / or a catheter configured for both sensing and ablation. An example catheter 14 is illustrated herein. The physician 24 brings the distal electrode 34 of the catheter 14 into contact with the heart wall for sensing and / or ablating a target site in the heart 12.

[0027] The catheter 14 optionally includes a magnetically based position sensor 29 embedded in the distal portion 28 of the catheter 14 for tracking the position and orientation of the distal portion 28. Preferably, the magnetically based position sensor 29 includes three magnetic coils for sensing three-dimensional (3D) position and orientation.

[0028] The magnetic-based position sensor 29 can operate with the positioning pad 25, which includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predefined working space. The real-time position of the distal portion 28 of the catheter 14 can be tracked based on the magnetic field generated by the positioning pad 25 and sensed by the magnetic-based position sensor 29. The details of the magnetic-based position sensing technology are described in U.S. Patents 5,391,199, 5,443,489, 5,558,091, 6,172,499, 6,239,724, 6,332,089, 6,484,118, 6,618,612, 6,690,963, 6,788,967 and 6,892,091, which are incorporated herein by reference.

[0029] The illustrated system 10 includes one or more electrode patches 38 positioned in contact with the skin of the patient 23 to establish a position reference for impedance-based tracking of the positioning pad 25 and one or more impedance-based tracking electrodes 26. For impedance-based tracking, current is directed toward the impedance-based tracking electrodes 26 and sensed at the electrode skin patch 38 so that the position of each electrode 26 can be triangulated via the electrode patch 38. Details of impedance-based position tracking techniques are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182, which are incorporated herein by reference and are attached as an appendix to this document. Instead of relying on the electrode patch 38, the catheter can utilize the existing impedance sensing electrodes 39' ( Figure 4B ), which is similar to the impedance sensing electrodes provided on the Biosense Webster Vizigo Sheath Introducer product (see the following website https: / / www.jnjmedtech.com / en-US / product / carto-vizigo-bi-directional-guiding- sheath ) and described in an article titled “FIRST EXPERIENCE WITH LEFT ATRIAL ARRHYTHMIA ABLATIONUSING A BIDIRECTIONAL STEERABLE TRANSSEPTAL SHEATH (VIZIGO) VISIBLE IN THE CARTO SYSTEM AS A METHOD TO REDUCE FLUOROSCOPY” published by EUROPEAN JOURNAL OF TRANSLATIONAL AND CLINICAL MEDICINE 2020;3(2):18-21, with corresponding author Edward PhD MD,I Chair and Department of Cardiology,MedicalUniversity of Warsaw,Edward Katarzynaojewska, Jarosaw Hiczkiewicz, and published online at: www.ejtcm.gumed.edu.pl A copy of the above article is incorporated herein by reference and is attached as an appendix hereto. In some embodiments, the sensing electrode 39' is optional, and the position of the sheath 40 can be determined without the sensing electrode 39'.

[0030] The guide sheath 40 may include a predetermined tubular wall region 42 that is positioned at a predetermined position relative to the distal end 43 of the sheath in the wall of the tubular shaft 47 of the guide sheath 40. The predetermined tubular wall region includes a low impedance path through the wall of the guide sheath 40. When the impedance-based tracking electrode 26 of the catheter 14 is positioned adjacent to the predetermined tubular wall region 42 of the guide sheath 40, current is directed to the impedance-based tracking electrode 26, through the predetermined tubular wall region 42, and sensed at the electrode skin patch 38, so that the position of the predetermined tubular wall region 42 can be triangulated via the electrode patch 38 using the systems and methods disclosed in U.S. Pat. Nos. 7,536,218; 7,756,576; 7,848,787; 7,869,865; and 8,456,182, their variations, and their alternatives, which are incorporated herein by reference and attached in the appendix to this document, as understood by those skilled in the art.

[0031] The predetermined tubular wall region 42 may be disposed approximately 1 centimeter from the distal end 43 of the tubular shaft of the sheath 40 and extend approximately 1 to 2 millimeters along the tubular shaft.

[0032] The predetermined tubular wall region 42 may include various features to facilitate electrical conduction through the tubular wall at the predetermined tubular wall region 42. For example, the predetermined tubular wall region may include holes sized to allow saline to flow from the lumen through the tubular wall of the tubular shaft, conductive ribbons coupled to the tubular wall of the introducer sheath and configured to conduct electrical current between the lumen and an environment external to the tubular shaft, conductive rivets extending through the tubular wall of the introducer sheath, conductive fibers embedded in the tubular wall of the introducer sheath and configured to conduct electrical current between the lumen and an environment external to the tubular shaft, combinations thereof, or variations thereof in various combinations.

[0033] The introducer sheath 40 also includes a sheath handle 44 coupled to the proximal end of the tubular shaft 47. The handle 44 can be configured to deflect the distal portion 41 of the tubular shaft 47 of the introducer sheath 40. The introducer sheath 40 can also include an irrigation port configured to be connected to an irrigation system 51 to provide irrigation fluid to the lumen of the introducer sheath 40. When the predetermined tubular wall region 42 includes holes, saline flowing through the holes can provide an electrically conductive path through the tubular wall of the tubular shaft 47 of the introducer sheath 40. The distal portion 41 of the introducer sheath 40 can be positioned based on an impedance signal of the saline solution in the holes through the predetermined tubular wall region 42.

[0034] The tubular shaft 47 of the guide sheath 40 may lack an active position sensor. Impedance-based tracking based on electrical signals passing through a predetermined tubular wall region 42 may be sufficient to track the distal portion 41 of the guide sheath 40. The guide sheath 40 may also lack an electrical port. Impedance-based tracking based on electrical signals passing through a predetermined tubular wall region 42 may be sufficient to track the distal portion 41 of the guide sheath 40 without any electrical signals being transmitted along the length of the tubular shaft 47.

[0035] The impedance-based tracking electrode 26 may be multifunctional and may be additionally configured for sensing and / or ablation.

[0036] Recorder 11 displays electrograms 21 captured using surface ECG electrodes 18 and intracardiac electrograms (IEGMs) captured using one or more electrodes 26, 34 of catheter 14. Recorder 11 may include pacing capabilities for pacing the cardiac rhythm and / or may be electrically connected to a separate pacemaker.

[0037] The system 10 may include an ablation energy generator 50 adapted to conduct ablation energy to the distal electrode 34 of the catheter 14. The energy generated by the ablation energy generator 50 may include, but is not limited to, radio frequency (RF) energy or pulsed field ablation (PFA) energy (including monopolar or bipolar high voltage DC pulses that may be used to achieve irreversible electroporation (IRE)), or a combination thereof.

[0038] The patient interface unit (PIU) 30 is an interface configured to establish electrical communication between catheters, electrophysiology equipment, a power source, and a workstation 55 for controlling the operation of the system 10. The electrophysiology equipment of the system 10 may include, for example, multiple catheters, positioning pads 25, surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally and preferably, the PIU 30 includes processing capabilities for enabling real-time calculation of the position of the catheter and for performing ECG calculations.

[0039] Workstation 55 includes memory, a processor unit with memory or storage loaded with appropriate operating software, and user interface capabilities. Workstation 55 can be configured to provide a variety of functions, optionally including: (1) three-dimensional (3D) modeling of endocardial anatomy and rendering of the model or anatomical map 20 for display on display device 27; (2) displaying on display device 27 an activation sequence (or other data) compiled from recorded electrograms 21 as representative visual markers or images superimposed on the rendered anatomical map 20; (3) displaying the real-time position and orientation of a graphical representation 53 of catheter 40 and / or a graphical representation 52 of catheter 14 within a cardiac chamber; and (4) displaying on display device 27 a site of interest, such as where ablation energy is applied. A commercial product embodying elements of system 10 may be CARTOTM The 3 system was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0040] Figure 2 is an illustration of an exemplary introducer sheath 40 and catheter 14. The introducer sheath 40 includes a handle 44, a flushing port 49 extending proximally from the handle 44, and a tubular shaft 47 extending distally from the handle 44. The tubular shaft 47 has a distal portion 41 and a predetermined tubular wall region 42 in the distal portion 41. The handle 44 includes a knob 48 that can be manipulated to deflect the distal portion 41 of the tubular shaft 47, as shown.

[0041] The catheter 14 includes a handle 16 and a catheter shaft 17 extending distally from the catheter handle 16. The catheter shaft 17 includes an impedance-based tracking electrode 26 and a distal electrode 34. The distal portion of the catheter shaft 17 can be deflected by manipulating a catheter knob 19 on the catheter handle 16.

[0042] The guide sheath 40 includes a lumen therethrough through which the shaft of the catheter 14 can translate. As shown, the catheter shaft can extend through the handle 44 of the guide sheath 40, through the tubular shaft 47 of the guide sheath, and from the distal end 43 of the guide sheath 40. When the impedance-based tracking electrode 26 of the catheter 14 is aligned with the predetermined tubular wall region 42, there is a conductive path through the predetermined tubular wall region 42 to the impedance-based tracking electrode 26.

[0043] Figure 3A 4 is an illustration of the distal portion 41 of the sheath 40. The tubular shaft 47 includes a proximal conductive region 46 and a distal conductive region 45. Each conductive region 45, 46 is configured similarly to Figure 1 , Figure 2 , Figure 4A , Figure 4B , Figure 5 and FIG. 6A to FIG. 6D 42. Each conductive region 45, 46 may include a hole sized to allow saline to flow from the lumen through the tubular wall of the tubular shaft, a conductive ribbon coupled to the tubular wall of the introducer sheath and configured to conduct current between the lumen and the external environment of the tubular shaft, a conductive rivet extending through the tubular wall of the introducer sheath, a conductive fiber embedded in the tubular wall of the introducer sheath and configured to conduct current between the lumen and the external environment of the tubular shaft, a combination thereof, or a variation thereof in various combinations. Each conductive region 45, 46 can be otherwise configured to provide a conductive path through the tubular wall of the tubular shaft 47 of the introducer sheath 40.

[0044] The distal conductive region 45 may be configured to be a predetermined distance L1 from the distal end 43 of the guide sheath 40. The proximal conductive region 46 may be configured to be a predetermined distance L3 from the distal end 43 of the guide sheath 40. The distal conductive region 45 may be shaped as a ring having a length L2 that surrounds the tubular shaft 47. The proximal conductive region 46 may be shaped as a ring having a length L4 that surrounds the tubular shaft 47.

[0045] Figure 3B is an illustration of the distal portion 28 of the catheter 14. The catheter 14 includes ring electrodes 31, 35, 36, 37, 39. Each of the ring electrodes may be configured similar to Figure 1 , Figure 2 , Figure 4A and Figure 4B The impedance tracking electrode 26 of the impedance-based tracking electrode 26 shown in . The catheter 14 may include a distal ring electrode 31 disposed at a first distance L5 from the distal end 33 of the catheter 14, a second ring electrode 35 disposed at a second distance L6 from the distal end 33 of the catheter 14, a third ring electrode 35 disposed at a third distance L7 from the distal end 33 of the catheter 14, a fourth ring electrode 35 disposed at a fourth distance L8 from the distal end 33 of the catheter 14, and a fifth ring electrode 35 disposed at a fifth distance L9 from the distal end 33 of the catheter 14.

[0046] like Figure 3A and Figure 3BAs shown, the guide sheath 40 may include a plurality of conductive regions 45, 46, and the catheter 14 may include a plurality of ring electrodes 31, 35, 36, 37, 39. Some or all of the ring electrodes 31, 35, 36, 37, 39 may be configured as impedance tracking electrodes. When the catheter 14 is translated distally through the guide sheath 40, the ring electrodes 31, 35, 36, 37, 39 pass through the conductive regions 45, 46. The distances L1, L3 and the distances L5, L6, L7, L8, L9 between the conductive regions 45, 46 and the distal end 43 of the guide sheath 40 may be configured so that two of the ring electrodes 31, 35, 36, 37, 39 are aligned with the conductive regions 45, 46 at the same time, so that the positions of the conductive regions 45, 46 can be determined simultaneously by the impedance-based tracking system. The distances L1, L3, L5, L6, L7, L8, L9 may be further configured such that when two of the ring electrodes (e.g., the two most proximal electrodes 37, 39) are simultaneously aligned with the conductive regions 45, 46, the third electrode (e.g., one or both of the intermediate electrodes 35, 36) is positioned distal to and proximal to the distal end 43 of the guide sheath 40, such that the positions of the conductive regions 45, 46 and the position of the distal end 43 of the guide sheath 40 may be determined by an impedance-based tracking system. The curvature of the distal portion 41 of the guide sheath 40 may be determined based on the positions of the conductive regions 45, 46 and the distal end 43. The impedance-based tracking system may further determine the position and curvature of the distal portion of the catheter 14 based on the positions of the ring electrodes 31, 35, 36, 37, 39 located distal to the distal end 43 of the guide sheath 40.

[0047] The catheter 14 shown is a focal ablation catheter. Examples of focal ablation catheters include the Biosense Webster THERMOCOOL SF, THERMOCOOL and RMT. Optionally, the catheter 14 can be another therapeutic or diagnostic catheter configured with at least one impedance-based tracking electrode 26. The catheter 14 may include a linear end effector (as shown), a cable or curved end effector, a basket end effector, a balloon end effector, a light end effector, variations thereof, or alternatives thereof, as understood by those skilled in the art. The end effector of the catheter 14 may include one or more electrodes configured to sense intracardiac electrogram signals. The end effector of the catheter 14 may include one or more electrodes configured to provide electrical signals for radiofrequency ablation and / or irreversible electroporation.

[0048] As an alternative to catheter 14, system 10 ( Figure 1) can be configured with a medical probe having at least one impedance-based tracking electrode 26. For example, a dilator having at least one impedance-based tracking electrode 26 or a medical probe having a dilator and at least one impedance-based tracking electrode 26 can be used in place of the catheter 14.

[0049] At least one of the predetermined tubular wall regions 45, 46 is preferably disposed about 1 cm to about 3 cm from the distal end 43 of the tubular shaft 47 of the introducer sheath 40. The length L2, L4 of the predetermined tubular wall region is preferably about 1 mm to about 2 mm.

[0050] Figure 4A 1 is an illustration of an impedance-based tracking system in which the impedance-based tracking electrode 26 of the catheter 14 is not adjacent to the predetermined tubular wall region 42 of the sheath 40. For purposes of illustration, the catheter 14 includes only one impedance-based tracking electrode 26, and the sheath 40 includes only one predetermined tubular wall region 42. The catheter 14 and / or the sheath 40 may alternatively be configured as described with respect to Figure 3A and Figure 3B The catheter 14 is positioned with its tubular body within the tubular body of the introducer sheath 40 such that the tubular bodies of the catheter 14 and the introducer sheath 40 are aligned along the longitudinal axis AA.

[0051] The impedance-based tracking system includes an introducer sheath 40 , a catheter 14 (or other suitable medical probe), a body patch 38 , and a control unit 56 . Figure 4A and Figure 4B Including Figure 1 Elements of system 10 are shown.

[0052] When the impedance-based tracking electrode 26 is not aligned with the predetermined tubular wall region 42, there is no direct path for current flow between the impedance-based tracking electrode 26 and the body patch 38, and thus the impedance between the impedance-based tracking electrode 26 and the body patch 38 is high. When the impedance-based tracking electrode 26 is not aligned with the predetermined tubular wall region 42, it may be difficult or impossible to determine the position of the impedance-based tracking electrode 26.

[0053] Figure 4B4 is an illustration of an impedance-based tracking system in which an impedance-based tracking electrode 26 is adjacent to a predetermined tubular wall region 42 of an introducer sheath 40. When the impedance-based tracking electrode 26 is aligned with the predetermined tubular wall region 42, an electric current may be conducted between the body patch electrode 38 and the impedance-based tracking electrode 26 through the predetermined tubular wall region 42. In addition or alternatively, a sensing electrode 39' may be used in place of the body patch electrode 38. The control unit 56 may be configured to determine the location of the predetermined tubular wall region 42 based at least in part on an electrical signal between the tracking electrode 26 and the body patch electrode 38. The controller may be configured to drive an electric current between the body patch electrode 38 and the impedance-based tracking electrode 26. The controller may be configured to measure the impedance between the impedance-based tracking electrode 26 and the body patch electrode 38 to determine the distance between each of the impedance-based tracking electrode 26 and the body patch electrode 38, thereby determining the three-dimensional coordinates of the impedance-based tracking electrode 26.

[0054] When the impedance-based tracking electrode 26 is not aligned with the position (e.g., Figure 4A ) to an aligned position (e.g. Figure 4B ), the impedance between the impedance-based tracking electrode 26 and each of the body patch electrodes 38 decreases sharply. The control unit 56 may be configured to determine the alignment of the impedance-based tracking electrode 26 with the predetermined tubular wall region 42 by detecting the sharp decrease in impedance.

[0055] When the catheter 14 includes two or more impedance-based tracking electrodes 26 (e.g., Figure 3B When the ring electrodes 31, 35, 36, 37, 39 are shown, at least one of the impedance-based tracking electrodes may be in a misaligned position (e.g., Figure 4A ), and at least one of the impedance-based tracking electrodes is aligned with one or more conductive areas of the introducer sheath 40. A higher impedance may exist between the impedance-based tracking electrode and the body patch electrode 38 in the misaligned position compared to the impedance between the impedance-based tracking electrode and the body patch electrode 38 in the aligned position. The control unit 56 may be configured to determine which impedance-based tracking electrode is in the aligned position or in the misaligned position based on a comparison of the impedance between each impedance-based tracking electrode and the body patch electrode 38. The controller may be configured to determine that those impedance-based tracking electrodes with higher impedance are misaligned, and those tracking electrodes with lower impedance are aligned. The controller may be configured to determine the position of each predetermined tubular wall region based on the position of each impedance-based tracking electrode in the aligned position.

[0056] The control unit 56 may be configured to determine the position of the distal end 43 of the tubular shaft of the introducer sheath 40 based at least in part on the position of the predetermined tubular wall region 42 .

[0057] The control unit 56 may be configured to determine the position and orientation of the distal portion 41 of the introducer sheath 40 relative to the patient's anatomy. Figure 1 As shown, the system 10 can be configured to generate an anatomical map 20. A graphical representation 52 of a distal portion of the catheter 14 can be superimposed on the anatomical map 20 based on magnetic and / or impedance-based tracking of the catheter 14. A graphical representation 53 of the distal portion 41 of the introducer sheath 40 can be superimposed on the anatomical map 20 based on impedance-based tracking of a predetermined tubular wall region 62 (or a plurality of predetermined tubular wall regions).

[0058] The control unit 56 may be configured to determine the position and orientation of the distal portion 41 of the introducer sheath 40 without relying on an active position sensor on the tubular shaft 47 of the introducer sheath 40. The control unit 56 may be configured to determine the position and orientation of the distal portion 41 of the introducer sheath 40 lacking an active position sensor.

[0059] Control unit 56 may be configured to determine the position and orientation of distal portion 41 of introducer sheath 40 without relying on any electrical signal connection to introducer sheath 40. Control unit 56 may be configured to determine the position and orientation of distal portion 41 of introducer sheath 40 lacking an electrical port.

[0060] like Figure 4B The sensing electrodes 39' shown are optional. Additionally or alternatively, the sensing electrodes 39' may be used in place of the body patch electrodes 38 or as an alternative.

[0061] Figure 5 is an illustration of the distal portion 41 of the introducer sheath 40 .

[0062] Fig. 6A , Figure 6B , Figure 6C and Fig.6D Yes Figure 5 A cross-sectional view of a distal portion 41 of an introducer sheath 40 is shown illustrating an exemplary configuration of a predetermined tubular wall region 42 configured to provide an electrically conductive path through the tubular wall.

[0063] Fig. 6A An example is shown in which the predetermined tubular wall region 42a includes a structure similar to Figure 1 The cross-section of the circular holes 62a is shown. These holes can allow saline to flow through the lumen of the introducer sheath 40 to provide a conductive path through the tubular wall of the introducer sheath 40. Alternatively, the tubular wall region 42 can include a circular plug filled with a conductive material (e.g., a conductive polymer or metal) as a substitute for saline.

[0064] Figure 6BA cross section is illustrated wherein the predetermined tubular wall region 42b comprises a conductive rivet 62b extending through the wall of the first tubular shaft. The rivet comprises a conductive material (eg, a conductive polymer or metal).

[0065] Figure 6C A cross section is illustrated wherein the predetermined tubular wall region 42c comprises a conductive ribbon 62c or ring coupled to the wall of the tubular shaft of the introducer sheath 40 and configured to conduct electrical current between the lumen and an environment external to the tubular shaft.

[0066] Fig.6D A cross section is illustrated wherein the predetermined tubular wall region 42d comprises conductive fibers 62d embedded in the wall of the tubular shaft of the introducer sheath 40. The conductive fibers 62d are configured to conduct electrical current between the lumen of the tubular shaft of the introducer sheath 40 and an environment external to the tubular shaft.

[0067] Figure 7 FIG. 1 is an illustration of a flow chart of a method 100 for impedance tracking an introducer sheath within a patient. As will be appreciated by those skilled in the art, the method 100 may be implemented using, for example, Figure 4A and Figure 4B The system shown and Figure 1 The system 10 shown, their variations, and their alternatives are implemented. The introducer sheath can be constructed to have the features of the introducer sheath 40 illustrated herein, their variations, and their alternatives, as understood by those skilled in the art.

[0068] At box 102, a current signal can be passed between a probe electrode of a medical probe and a plurality of body patch electrodes, wherein the probe electrode is disposed within a lumen of an introducer sheath within a patient's body and the plurality of body patch electrodes are in contact with the patient's skin. The probe electrode can be configured to be similar to any of the impedance-based tracking electrodes 26, 31, 35, 36, 37, 39 illustrated herein, their variations, and their alternatives, as understood by those skilled in the art. The plurality of body patch electrodes can be configured to be similar to the body patch electrode 38 illustrated herein, their variations, and their alternatives, as understood by those skilled in the art. The medical probe can be configured to be similar to a catheter 14, a dilator, a medical probe with a dilator, other such medical probes disclosed herein, their variations, and their alternatives, as understood by those skilled in the art. The current signal can be transmitted by a control unit (such as Figure 4A and Figure 4B The exemplary control unit 56), the patient interface unit (such as Figure 1 The PIU 30 shown), variations thereof, and alternatives thereof, conduct between body patch electrodes and probe electrodes, as will be understood by those skilled in the art.

[0069] At block 104, translation of the probe electrode through the lumen adjacent to a predetermined tubular wall region of the wall of the introducer sheath is detected. The predetermined tubular wall region may be configured similar to the predetermined tubular wall regions 62, 62a-62d or conductive regions 45, 46 illustrated herein, variations thereof, and alternatives thereof, as understood by those skilled in the art.

[0070] At block 106, the current signal may be passed between the probe electrode and the plurality of body patch electrodes such that the current signal passes through a predetermined tubular wall region of the wall of the introducer sheath. The predetermined tubular wall region may include a saline-filled hole through the wall of the introducer sheath, and the current signal may pass through the saline-filled hole.

[0071] At frame 108, the position of the predetermined tubular wall region can be determined at least in part based on the current signal. The position of the distal end of the guide sheath can be determined at least in part based on a predetermined distance between the predetermined tubular wall region and the distal end of the guide sheath. In addition or alternatively, the current signal can be connected to the wall of the guide sheath at the predetermined tubular wall region through a conductive strip. In addition or alternatively, the current signal can be extended through a conductive rivet through the wall of the guide sheath at the predetermined tubular wall region. In addition or alternatively, the current signal can be embedded in the wall of the guide sheath at the predetermined tubular wall region. Conductive fibers. The position and orientation of the distal portion of the guide sheath can be determined relative to the patient's anatomical structure. The position of the distal portion of the guide sheath can be determined without the need for an active position sensor on the guide sheath. The position of the distal portion of the guide sheath can be determined without the need for active electrical communication with the guide sheath.

[0072] At block 110 , a graphical representation of the distal portion of the introducer sheath relative to the patient's anatomy can be generated based at least in part on the location of the conductive region.

[0073] The following clauses set forth non-limiting embodiments of the present disclosure:

[0074] Item 1. A guide sheath comprising: a tubular shaft extending along a longitudinal axis between a proximal end and a distal end, the tubular shaft comprising a lumen extending through the tubular shaft and a tubular wall surrounding the lumen, such that a predetermined tubular wall region is configured to provide a conductive path through the tubular wall of the tubular shaft, the predetermined tubular wall region being disposed adjacent to the distal end of the tubular shaft.

[0075] Clause 2. The introducer sheath of Clause 1, wherein the predetermined tubular wall region is disposed approximately 1 centimeter from the distal end and extends approximately 1 to 2 millimeters along the tubular shaft.

[0076] Clause 3. The introducer sheath of clause 1 or 2, the predetermined tubular wall region being configured to have pores sized to allow saline to flow from the lumen through the tubular wall of the tubular shaft.

[0077] Clause 4. The introducer sheath of any one of clauses 1 to 3, the predetermined tubular wall region comprising a conductive tape coupled to the tubular wall of the introducer sheath and configured to conduct electrical current between the lumen and an environment external to the tubular shaft.

[0078] Clause 5. The introducer sheath of any one of clauses 1 to 4, the predetermined tubular wall region comprising a conductive rivet extending through the tubular wall of the introducer sheath.

[0079] Clause 6. The introducer sheath of any one of clauses 1 to 5, the predetermined tubular wall region comprising conductive fibers embedded in the tubular wall of the introducer sheath and configured to conduct electrical current between the lumen and an environment external to the tubular shaft.

[0080] Clause 7. The introducer sheath of any one of clauses 1 to 6, further comprising: a handle coupled to the proximal end of the tubular shaft and configured to deflect a distal portion of the tubular shaft.

[0081] Clause 8. The introducer sheath of any one of Clauses 1 to 7, further comprising: a flushing port configured to provide flushing fluid to the lumen.

[0082] Clause 9. An introducer sheath according to any one of clauses 1 to 8, wherein the tubular shaft lacks an active position sensor.

[0083] Clause 10. The introducer sheath of any one of clauses 1 to 9, wherein the introducer sheath lacks an electrical port.

[0084] Clause 11. A guide sheath according to any one of clauses 1 to 10, wherein the tubular shaft includes a plurality of predetermined tubular wall regions, including the predetermined tubular wall region, wherein each of the plurality of predetermined tubular wall regions is disposed at a corresponding predetermined length from the distal end of the tubular shaft, and wherein each of the plurality of predetermined tubular wall regions provides a conductive path through the tubular wall of the tubular shaft.

[0085] Item 12. An impedance-based tracking system, the tracking system comprising: a guide sheath comprising a first tubular shaft and a predetermined tubular wall region, the first tubular shaft comprising a lumen extending therethrough, the predetermined tubular wall region being disposed near a distal end of the first tubular shaft, the predetermined tubular wall region being configured to provide a conductive path through the predetermined tubular wall region; a medical probe comprising a second tubular shaft configured to translate through the lumen of the first tubular shaft and comprising a tracking electrode coupled to the second tubular shaft; a plurality of body patch electrodes configured to contact the patient's skin; and a control unit configured to determine a position of the predetermined tubular wall region based at least in part on an electrical signal between the tracking electrode and the plurality of body patch electrodes.

[0086] Clause 13. The impedance-based tracking system of Clause 12, the control unit further configured to determine a position of the distal end of the first tubular shaft of the introducer sheath based at least in part on the position of the predetermined tubular wall region.

[0087] Clause 14. The impedance-based tracking system of clause 12 or 13, wherein the control unit is further configured to determine a position and orientation of a distal portion of the introducer sheath relative to an anatomical structure of the patient.

[0088] Clause 15. The impedance-based tracking system of any of clauses 12 to 14, the predetermined tubular wall region being configured with pores sized to allow saline to flow from the lumen through the wall of the first tubular shaft.

[0089] Clause 16. The impedance-based tracking system of Clause 15, further comprising: an irrigation source configured to provide saline through the lumen and the aperture of the first tubular shaft.

[0090] Clause 17. The impedance-based tracking system of any of clauses 12 to 16, the predetermined tubular wall region comprising a conductive tape coupled to a wall of the first tubular shaft and configured to conduct electrical current between the lumen and an environment external to the first tubular shaft.

[0091] Clause 18. The impedance-based tracking system of any of Clauses 12 to 17, the predetermined tubular wall region comprising a conductive rivet extending through a wall of the first tubular shaft.

[0092] Clause 19. The impedance-based tracking system of any of clauses 12 to 18, the predetermined tubular wall region comprising conductive fibers embedded in the wall of the first tubular shaft and configured to conduct electrical current between the lumen and an environment external to the first tubular shaft.

[0093] Clause 20. The impedance-based tracking system of any one of clauses 12 to 19, wherein the predetermined tubular wall region is disposed about 1 cm to about 3 cm from the distal end of the first tubular shaft and extends along the first tubular shaft for a length of about 1 mm to about 2 mm.

[0094] Clause 21. The impedance-based tracking system of any one of clauses 12 to 20, the introducer sheath comprising a handle coupled to a proximal end of the first tubular shaft and configured to deflect a distal portion of the first tubular shaft.

[0095] Clause 22. The impedance-based tracking system of any one of clauses 12 to 21, the introducer sheath comprising a flushing port configured to provide flushing fluid to the lumen.

[0096] Clause 23. The impedance-based tracking system of any one of clauses 12 to 22, wherein the first tubular shaft lacks an active position sensor.

[0097] Clause 24. The impedance-based tracking system of any one of clauses 12 to 23, wherein the introducer sheath lacks an electrical port.

[0098] Clause 25. An impedance-based tracking system according to any one of clauses 12 to 24, wherein the first tubular shaft comprises a plurality of conductive regions, including the conductive region, wherein each of the plurality of conductive regions is disposed a respective predetermined length from the distal end of the first tubular shaft, and wherein each of the plurality of predetermined conductive regions provides a conductive path between the lumen of the first tubular shaft and an external environment of the first tubular shaft.

[0099] Clause 26. The impedance-based tracking system of any of Clauses 12 to 25, the medical probe further comprising one or more electrodes configured to sense intracardiac electrogram signals.

[0100] Clause 27. The impedance-based tracking system of any one of clauses 12 to 26, the medical probe further comprising one or more electrodes configured to provide electrical signals for radiofrequency ablation.

[0101] Clause 28. The impedance-based tracking system of any one of clauses 12 to 27, the medical probe further comprising one or more electrodes configured to provide an electrical signal for ablation via irreversible electroporation.

[0102] Clause 29. The impedance-based tracking system of any one of clauses 12 to 28, the medical probe comprising a dilator.

[0103] Item 30. A method for impedance tracking of a guide sheath within a patient, the method comprising: passing a current signal between a probe electrode of a medical probe and a plurality of body patch electrodes, the probe electrode being disposed within a lumen of the guide sheath within the patient, and the plurality of body patch electrodes being in contact with the patient's skin; and determining a position of a distal portion of the guide sheath based at least in part on the current signal.

[0104] Clause 31. The method of Clause 30, further comprising: detecting translation of the probe electrode through the lumen adjacent to a predetermined tubular wall region of a wall of the introducer sheath.

[0105] Clause 32. The method according to Clause 31, further comprising: determining the position of the predetermined tubular wall region; and determining the position of the distal end of the guide sheath based at least in part on a predetermined distance between the predetermined tubular wall region and the distal end of the guide sheath.

[0106] Clause 33. The method of clause 31 or 32, further comprising: passing the current signal between the probe electrode and the plurality of body patch electrodes such that the current signal passes through the predetermined tubular wall region of the wall of the introducer sheath.

[0107] Clause 34. The method of Clause 33, further comprising: passing the current signal through a saline-filled hole in the wall of the introducer sheath at the predetermined tubular wall region.

[0108] Clause 35. The method of clause 33 or 34, further comprising passing the current signal through a conductive strip coupled to the wall of the introducer sheath at the predetermined tubular wall region.

[0109] Clause 36. The method of any one of clauses 33 to 35, further comprising passing the current signal through a conductive rivet extending through the wall of the introducer sheath at the predetermined tubular wall region.

[0110] Clause 37. The method of any one of clauses 33 to 36, further comprising passing the current signal through conductive fibers embedded in the wall of the introducer sheath in the predetermined tubular wall region.

[0111] Clause 38. The method of any one of Clauses 30 to 37, further comprising: determining a position and orientation of a distal portion of the introducer sheath relative to anatomy of the patient.

[0112] Clause 39. The method of any one of clauses 30 to 38, further comprising determining the position of the distal portion of the introducer sheath without requiring an active position sensor on the introducer sheath.

[0113] Clause 40. The method of any one of clauses 30 to 39, further comprising determining the position of the distal portion of the introducer sheath without requiring active electrical communication on the introducer sheath.

[0114] Exemplary embodiments of the subject matter contained herein have been shown and described, and further improvements of the methods and systems described herein may be achieved by appropriate modifications without departing from the scope of the claims. In addition, where the above methods and steps represent specific events that occur in a specific order, it is intended that certain specific steps do not necessarily have to be performed in the order described, but can be performed in any order, as long as the steps enable the implementation to achieve its intended purpose. Therefore, if there are variations of the present invention and the variations belong to the substantive scope of the disclosure of the present invention or equivalents that can be found in the claims, this patent is intended to cover these variations as well. Many such modifications will be obvious to those skilled in the art. For example, the examples, embodiments, geometries, materials, dimensions, ratios, steps, etc. described above are all exemplary. Therefore, the claims should not be limited to the specific details of the structure and operation shown in this written description and the drawings.

Claims

1. An impedance-based tracking system, the impedance-based tracking system comprising: an introducer sheath comprising a first tubular shaft including a lumen extending therethrough and a predetermined tubular wall region disposed proximate a distal end of the first tubular shaft, the predetermined tubular wall region being configured to provide an electrically conductive path therethrough; a medical probe comprising a second tubular shaft configured to be translated through the lumen of the first tubular shaft and comprising a tracking electrode coupled to the second tubular shaft; a plurality of body patch electrodes configured to contact the patient's skin; and A control unit is configured to determine a location of the predetermined tubular wall region based at least in part on electrical signals between the tracking electrode and the plurality of body patch electrodes.

2. According to claim 1, the impedance-based tracking system, the control unit is further configured to determine the position of the distal end of the first tubular shaft of the guide sheath based at least in part on the position of the predetermined tubular wall region.

3. According to the impedance-based tracking system of claim 1, the control unit is further configured to determine the position and orientation of the distal portion of the guide sheath relative to the patient's anatomical structure.

4. The impedance-based tracking system of claim 1, the predetermined tubular wall region being configured with pores sized to allow saline to flow from the lumen through the wall of the first tubular shaft.

5. The impedance-based tracking system of claim 1, the predetermined tubular wall region comprising a conductive tape coupled to a wall of the first tubular shaft and configured to conduct electrical current between the lumen and an environment external to the first tubular shaft.

6. The impedance-based tracking system of claim 1, the predetermined tubular wall region comprising a conductive rivet extending through a wall of the first tubular shaft.

7. The impedance-based tracking system of claim 1, the predetermined tubular wall region comprising conductive fibers embedded in the wall of the first tubular shaft and configured to conduct electrical current between the lumen and an environment external to the first tubular shaft.

8. The impedance-based tracking system of claim 1, wherein the predetermined tubular wall region is disposed about 1 cm to about 3 cm from the distal end of the first tubular shaft and extends along the first tubular shaft for a length of about 1 mm to about 2 mm.

9. The impedance-based tracking system of claim 1, the introducer sheath comprising a handle coupled to a proximal end of the first tubular shaft and configured to deflect a distal portion of the first tubular shaft.

10. The impedance-based tracking system of claim 1, the introducer sheath comprising a flushing port configured to provide flushing fluid to the lumen.

11. The impedance-based tracking system of claim 1 , wherein: The first tubular shaft lacks an active position sensor.

12. The impedance-based tracking system of claim 1, wherein: The introducer sheath lacks an electrical port.

13. The impedance-based tracking system of claim 1, in, The first tubular shaft comprises a plurality of conductive regions, including the conductive region, wherein each of the plurality of conductive regions is disposed a respective predetermined length from the distal end of the first tubular shaft, and Wherein each of the plurality of conductive regions provides a conductive path between the lumen of the first tubular shaft and an external environment of the first tubular shaft.

14. The impedance-based tracking system of claim 1, the medical probe further comprising one or more electrodes configured to sense intracardiac electrogram signals.

15. The impedance-based tracking system of claim 1, the medical probe further comprising one or more electrodes configured to provide electrical signals for ablation.

16. The impedance-based tracking system of claim 1, the medical probe comprising a dilator.

17. A guide sheath, comprising: A tubular shaft extending along a longitudinal axis between a proximal end and a distal end, the tubular shaft comprising a lumen extending therethrough and a tubular wall surrounding the lumen, such that a predetermined tubular wall region is configured to provide an electrically conductive path through the tubular wall of the tubular shaft, the predetermined tubular wall region being disposed proximate the distal end of the tubular shaft.

18. The introducer sheath of claim 17, the predetermined tubular wall region being disposed approximately 1 cm from the distal end and extending approximately 1 mm to 2 mm along the tubular shaft.

19. The introducer sheath according to claim 17, wherein: The tubular shaft comprises a plurality of predetermined tubular wall regions, including the predetermined tubular wall region, wherein each of the plurality of predetermined tubular wall regions is disposed a respective predetermined length from the distal end of the tubular shaft, and wherein each of the plurality of predetermined tubular wall regions provides an electrically conductive path through the tubular wall of the tubular shaft.

20. A method for impedance tracking of an introducer sheath in a patient, the method comprising: Passing a current signal between a probe electrode of a medical probe and a plurality of body patch electrodes, the probe electrode being disposed within a lumen of the introducer sheath within the patient's body, and the plurality of body patch electrodes being in contact with the patient's skin; and A position of a distal portion of the introducer sheath is determined based at least in part on the current signal.

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