Cryoablation element with conductive sleeve

Abstract

An ablation device for producing a lesion in a target tissue, the ablation device comprising a handle, an elongated shaft extending from the handle to a distal tip, wherein the shaft comprises a first portion, an ablation portion distal to the first portion and having an outer sheath, and at least one ablation energy element disposed within the outer sheath, wherein a space is formed between the at least one ablation energy element and the outer sheath. The ablation device also comprises a thermally conductive bushing disposed within the space.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 615,573, filed on January 10, 2018, the entire contents of which are incorporated herein by reference in their entirety for all purposes. background

[0003] 1. Field of the Invention

[0004] Embodiments of the present invention relate to surgical devices and, more particularly, to surgical instruments for applying thermal energy to ablate tissue.

[0005] 2. Description of the Prior Art

[0006] Atrial flutter and atrial fibrillation are heart conditions in which the left or right atrium of the heart does not beat normally. Atrial flutter is a condition in which the atria beat very quickly, but still evenly. Atrial fibrillation is a condition in which the atria beat very quickly, but unevenly.

[0007] These disorders are usually caused by abnormal electrical behavior of a portion of the atrium wall. Some part of the atrium or nearby structures (such as the pulmonary veins) may fail in their generation or conduction of the electrical signals that control the heart's contraction, resulting in abnormal electrical signals that cause the atrium to contract between normal contractions caused by the normal cascade of electrical impulses. This can be caused, for example, by spots of ischemic tissue called ectopic lesions, or by electrically active fibers in the pulmonary veins.

[0008] Ventricular tachycardia (V-tach or VT) is a regular, rapid heart rate caused by inappropriate electrical activity in the ventricles. In ventricular tachycardia, abnormal electrical signals in the ventricles cause the heart to beat faster than normal, usually 100 beats per minute or more, out of sync with the upper chambers. When this happens, the heart may not be able to pump enough blood to the body and lungs because the chambers do not have time to fill properly because they are beating too fast or out of sync with each other. As a result, V-tach can cause cardiac arrest and may turn into ventricular fibrillation.

[0009] Atrial fibrillation is one of the more common types of heart disease. If left untreated, atrial fibrillation can lead to a number of adverse consequences, including heart palpitations, shortness of breath, weakness, and generally poor blood flow to the body.

[0010] Various techniques are used to treat atrial fibrillation. One technique to treat AF is pulmonary vein isolation (PVI). PVI is performed by creating lesions around the pulmonary veins. PVI is used to block erroneous or abnormal electrical signals.

[0011] However, one challenge in performing PVI is obtaining durable or permanent isolation of the pulmonary veins. Various studies have highlighted this shortcoming. In a long-term follow-up study that investigated pulmonary vein reconnection rates after primary isolation, 53% of 161 patients were free of AF. Repeat ablation was performed for recurrent arrhythmias in 66 patients. The pulmonary vein reconnection rate was as high as 94% (62 of 66) (Ouyang F, Tilz R, Chun J, et al., “Long-term results of catheterization in paroxysmal atrial fibrillation: lessons from a 5-year follow-up,” Circulation 2010;122:2368-77).

[0012] One reason some PVI treatments are not durable is due to the phenomenon of pulmonary vein (or electrical) reconnection (Sawhney N, Anousheh R, Chen WC, et al., “Five-year outcomes after segmental pulmonary vein isolation for paroxysmal atrial fibrillation,” Am J Cardiol 2009;104:366-72)(Callans DJ, Gerstenfeld EP, Dixit S, et al., “Efficacy of repeat pulmonary vein isolation procedures in patients with recurrent atrial fibrillation,” J Cardiovasc Electrophysiol 2004;15:1050-5)(Verma A, Kilicaslan F, Pisano E, et al., “Response of atrial fibrillation to pulmonary vein antrum isolation is directly related to resumption and delay of pulmonary vein conduction,” Circulation 2005;112:627-35).

[0013] Pulmonary vein reconnection may be due to gaps in the veins and incomplete or discontinuous isolation (Bunch TJ, Cutler MJ., “Is pulmonary vein isolation still the cornerstone in atrial fibrillation ablation?” J Thorac Dis. 2015 Feb;7(2):132-41). Incomplete isolation is due to residual gaps within the circumferential lesion or lack of transmural injury. (McGann CJ, Kholmovski EG, Oakes RS, et al., “New magnetic resonance imaging-based method for defining the extent of left atrial wall injury after the ablation of atrial fibrillation”, J Am Coll Cardiol, 2008;52:1263-71) (Ranjan R, Kato R, Zviman MM, et al., “Gaps in the ablation line as a potential cause of recovery from electrical isolation and their visualization using MRI”, Circ Arrhythm Electrophysiol, 2011;4:279-86).

[0014] Furthermore, early recurrence of AF after ablation may be an early marker of incomplete pulmonary vein isolation. This is supported by a study of 12 patients who underwent a maze procedure after failed radiofrequency ablation. Notably, myocardial biopsy revealed anatomical gaps and / or nontransmural lesions in the pulmonary veins that had reconnected (Kowalski M, Grimes MM, Perez FJ, et al., “Histopathologic characterization of chronic radiofrequencyablation lesions for pulmonary vein isolation,” J Am Coll Cardiol, 2012;59:930-8).

[0015] This is further supported by a canine study that demonstrated endocardial block and postoperative gaps confirmed using MRI within the ablation line. Long-term follow-up data suggest that those pulmonary veins with gaps confirmed by MRI are more likely to reconnect electrically with recurrence of symptoms (Ranjan R, Kato R, Zviman MM, et al., “Gaps in the ablation line as potential cause of recovery from electrical isolation and their visualization using MRI,” Circ Arrhythm Electrophysiol, 2011;4:279-86).

[0016] Various attempts to address the above issues include combining circumferential pulmonary vein isolation (CPVI) with linear ablation. For example, one study compared the clinical outcomes of CPVI combined with additional linear ablation and CPVI in a prospective randomized controlled study in patients with paroxysmal AF. The study enrolled 100 patients with paroxysmal AF (75.0% male, age 56.4±11.6 years) who underwent radiofrequency circumferential ablation (RFCA) and were randomly divided into a CPVI group (n=50) or a catheter Dallas lesion group (CPVI, posterior box lesion and anterior linear ablation, n=50). The catheter Dallas lesion group required longer procedure time (190.3±46.3 vs 161.1±30.3 min, P<0.001) and ablation time (5345.4±1676.4 vs 4027.2±878.0 s, P<0.001) than the CPVI group. The rate of complete bidirectional block was 68.0% in the catheter Dallas lesion group and 100% in the CPVI group. The incidence of procedure-related complications was not significantly different between the catheter Dallas lesion group (0%) and the CPVI group (4%, P = 0.157). At a follow-up of 16.3 ± 4.0 months, there was no significant difference in the clinical recurrence rate between the two groups, regardless of whether complete bidirectional block was achieved after linear ablation (Kim et al., "Linear ablation in addition to circumferential pulmonary vein isolation (Dallas lesion set) does not improve clinical outcome in patients with paroxysmal atrial fibrillation: a prospective randomized study", Europace. 2015 Mar;17(3):388-95).

[0017] Therefore, adding more ablation points around the venous entry, and / or attempting to increase the linear lesion by using point-by-point ablation, does not appear to be the best solution to prevent gaps along the circumferential lesion, given the above-referenced studies. Furthermore, adding multiple points and lines would undesirably increase the procedure time.

[0018] In view of the above shortcomings, various ablation catheters including flexible cryoprobes or cryocatheters, bipolar RF catheters, monopolar RF catheters (using ground patches on the patient's skin), microwave catheters, laser catheters, and ultrasonic catheters have been proposed for lesion formation. For example, U.S. Patent No. 6,190,382 to Ormsby and U.S. Patent No. 6,941,953 to Feld describe RF ablation catheters for ablating cardiac tissue. These methods are attractive because they are minimally invasive and can be performed on a beating heart. However, these methods have a low success rate. The low success rate may be due to incomplete lesion formation. Complete transmural lesions require ensuring that the electrical impulses that cause atrial fibrillation are completely isolated from the rest of the atrium, and this is difficult to achieve with a beating heart surgery.

[0019] Therefore, the challenge for the surgeon is to place the catheter / probe along the correct tissue contour so that the probe makes full contact with the tissue. Due to the nature of the procedure and the anatomical location where the lesion must be created, the catheters must be flexible and adjustable enough so that they can match the shape and contour of the tissue to be ablated.

[0020] In U.S. Pat. Nos. 6,161,543 and 8,177,780 issued to Cox et al., a malleable and flexible cryoprobe is described. The described probe has a malleable shaft. A malleable metal rod is composited with a polymer to form the shaft. The malleable rod allows the user to plastically deform the shaft into a desired shape so that the tip can reach the tissue to be ablated.

[0021] US Patent No. 5,108,390 issued to Potocky et al. discloses a highly flexible cryoprobe that can be passed through a blood vessel and into the heart without an external guide other than the blood vessel itself.

[0022] However, a challenge with some of the above devices is making continuous contact along the anatomical surface, thereby creating a continuous lesion. This challenge is exacerbated by the fact that the contour and shape of the target tissue varies due to its location in the body, and also due to the anatomical variations between patients. Therefore, different treatment procedures and patient anatomy require different catheters to be designed and used. Another challenge is to be able to adjust the shape of the catheter in situ to account for these variations in anatomy, etc.

[0023] An additional challenge for some of the above devices is efficient heat conduction, i.e. cooling / heat transfer, between the internal cooling / heating elements of the device and the external sheath / cannula of the device. Thus, it may be necessary to efficiently transfer freezing and heating temperatures to the tissue to be ablated.

[0024] Therefore, there is a need for improved methods and systems for providing minimally invasive, shape-adjustable, safe and efficient cryogenic cooling of tissue. These improved systems include improved devices and methods to form continuous lesions in target tissue regardless of the disease being treated and variations in the patient's anatomy.

[0025] There is also a need for an improved device and method for treating AF, atrial flutter, and V-tach and achieving more complete, durable, and safe isolation of electrical signals within the various chambers of the heart, including pulmonary vein isolation.

[0026] Overview

[0027] An ablation device for producing a lesion in a target tissue, the ablation device comprising a handle, an elongated shaft extending from the handle to a distal tip, wherein the shaft comprises a first portion, an ablation portion distal to the first portion, and an outer sheath. The ablation device also comprises at least one ablation energy element disposed within the outer sheath, wherein a space is formed between the at least one ablation energy element and the outer sheath, and a thermally conductive bushing disposed within the space.

[0028] In an embodiment, the thermally conductive bushing is a thermoplastic elastomer or thermoplastic polyurethane filled with a thermally conductive material.

[0029] In an embodiment, the thermally conductive bushing is a polyether block amide (PEBA) loaded with alumina. In an embodiment, the PEBA is loaded with alumina in the range of about 50%-70% by weight. In some embodiments, the PEBA is loaded with boron nitride in the range of about 50%-70% by weight.

[0030] In an embodiment, the thermally conductive bushing is disposed in the space by flow melting to substantially fill the space and surround each ablation energy element.

[0031] In an embodiment, the ablation energy element is linear or elongated and is disposed longitudinally within the outer sheath.

[0032] In an embodiment, at least one ablation energy element comprises at least one ablation energy delivery lumen and at least one ablation energy return lumen. In an embodiment, each of the ablation energy delivery lumen and the at least one ablation energy return lumen comprises an inner tube having an outer tube surrounding the inner tube, thereby defining a gap between the inner tube and the outer tube. The gap can be filled with a thermally conductive liquid.

[0033] In an embodiment, the ablation device further comprises a plurality of ablation energy delivery lumens and a plurality of ablation energy return lumens.

[0034] In an embodiment, the ablation device further comprises at least one electrode and at least one service lumen on the outer surface of the outer sheath to provide electrical conductors or other functional elements to the ablation portion.

[0035] In an embodiment, the ablative energy is provided by a cryogen delivered through an ablative energy delivery lumen and at least one ablative energy return lumen. In an embodiment, the cryogen is nitrogen or nitrogen in a near critical state.

[0036] In an embodiment, the ablation device further comprises a stylet lumen and a stylet, the stylet lumen extending substantially along the length of the shaft from the handle to at least the ablation portion; the stylet can be inserted into the stylet lumen. In an embodiment, the stylet comprises a shape memory material, and wherein the stylet has a plurality of flexible portions along its length. In an embodiment, at least a distal portion of the stylet is preset with a shape corresponding to a desired shape of a lesion to be formed.

[0037] In an embodiment, the ablation device is used to treat a condition selected from the group consisting of atrial fibrillation, atrial flutter, and ventricular tachycardia.

[0038] In an embodiment, the thermally conductive sleeve completely surrounds each ablation energy element.

[0039] In embodiments, at least one ablation energy element reduces the temperature of the target tissue to cause ablation. In some embodiments, at least one ablation energy element increases the temperature of the target tissue.

[0040] In some embodiments, an ablation system for producing lesions in a target tissue is disclosed. The ablation system includes a catheter having a handle, a distal tip, and an elongated shaft extending from the handle to the distal tip. The shaft includes a first portion, an ablation portion distal to the first portion, and at least one ablation energy element, the ablation portion including an outer sheath, the ablation energy element being disposed within the outer sheath, wherein a space is formed between the at least one ablation energy element and the outer sheath. The shaft also includes a first thermally conductive medium disposed within the space. The system also includes an energy generator coupled to the catheter to deliver and control ablation energy from the at least one ablation energy element to the target tissue.

[0041] In an embodiment, a method for manufacturing an ablation catheter having an elongated ablation portion, the ablation portion comprising an outer sheath and an inner ablation element extending longitudinally therethrough, the method comprising flowing a conductive bushing between a space defined between the inner ablation element and the outer sheath. In an embodiment, the flowing step is performed by flowing a thermoplastic loaded with a thermally conductive agent.

[0042] In an embodiment, the flowing step is performed by flowing the thermoplastic loaded with the low linear thermal expansion coefficient agent.

[0043] In an embodiment, a method for ablating tissue includes any one or combination of the steps described herein, unless the steps are mutually exclusive.

[0044] In embodiments, a device for ablating tissue includes any one or combination of the structures described herein, unless such structures are mutually exclusive.

[0045] In an embodiment, a system for ablating tissue includes any one or combination of the components described herein, unless such components are mutually exclusive.

[0046] In another embodiment, an ablation catheter for creating a lesion in a target tissue is disclosed. The ablation catheter includes an elongated shaft extending from a handle to a distal tip, the shaft including an ablation portion distal to a first portion, wherein the ablation portion also includes an outer sheath; at least one ablation energy element disposed within the outer sheath, and a space is defined between the at least one ablation energy element and the outer sheath; and a thermally conductive bushing disposed within the space.

[0047] Some embodiments relate to a thermally conductive material comprising a base material selected from the group including thermoplastic elastomers (TPE) and thermoplastic polyurethanes (TPU) and a thermally conductive filler selected from the group including aluminum, aluminum oxide, boron nitride, copper, silver, and gold. In some embodiments, the base material is polyether block amide (PEBA). In some embodiments, the thermally conductive filler is aluminum oxide (Al2O3) or boron nitride (BN). In some embodiments, PEBA is filled with about 10%-70% by weight of aluminum oxide (Al2O3) or boron nitride (BN).

[0048] The description, objects and advantages of embodiments of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above aspects and other features, aspects and advantages of the present technology will now be described in conjunction with various embodiments with reference to the accompanying drawings. However, the illustrated embodiments are merely examples and are not intended to be limiting. Throughout the drawings, similar symbols generally identify similar components unless the context dictates otherwise. Note that the relative dimensions of the following drawings may not be drawn to scale.

[0051] Figure 1 A typical refrigerant phase diagram is illustrated;

[0052] Figure 2 is a schematic diagram of a cryogenic cooling system;

[0053] Figure 3 is corresponding to Figure 2 Refrigerant phase diagram for the system shown, where the refrigerant is N2;

[0054] Figure 4 Provides a summary Figure 2 Flowcharts of various aspects of the cooling system;

[0055] 5A is a perspective view of a cryoablation catheter according to an embodiment of the present invention;

[0056] FIG5B is a cross-sectional view taken along line 5B-5B in FIG5A;

[0057] Figure 6 is a diagram of a cryoablation system including a cryoablation catheter according to an embodiment of the present invention;

[0058] Figure 7 yes Figure 6 An enlarged perspective view of a distal segment of a cryoablation catheter is shown;

[0059] Figure 8 is a perspective view of another embodiment of a cryoablation catheter having a flexible distal treatment segment;

[0060] Fig.9A It is along Figure 8 The line 9A-9A in Figure 8 A cross-sectional view of an embodiment of a catheter shown in ;

[0061] Fig. 9B yes Fig.9A an enlarged view of one of the multilayer tubes shown in ;

[0062] Fig. 9C is a cross-sectional view of another embodiment of a cryoablation catheter;

[0063] Fig. 10A yes Figure 8 A partial cross-sectional view of an embodiment of the catheter shown;

[0064] Fig. 10B is the proximal end of the tube element and Figure 8 A partially exploded view of the distal end of the intermediate section of the embodiment of the catheter shown in FIG.

[0065] Fig.11 is a perspective view of another embodiment of a cryoablation catheter having a flexible distal treatment segment;

[0066] Fig.12 yes Fig.11 An enlarged view of a portion of the distal segment is shown;

[0067] Fig.13 It is along Fig.12 The line 13-13 is intercepted Fig.12 A cross-sectional view of the catheter shown in ;

[0068] Figure 14-15 Picture shows Fig.11 The distal segment of the catheter is shown deployed from the sequence of outer sheath components;

[0069] Fig.16 is a perspective view of another embodiment of a cryoablation catheter having a flexible distal treatment segment;

[0070] Fig.17 yes Fig.16 An enlarged view of the distal segment of the catheter is shown;

[0071] Fig.18 It is along Fig.17 The line 17-17 is intercepted Fig.17 A cross-sectional view of the catheter shown in ;

[0072] Figures 19A-19D shows deployment of a distal segment of a catheter according to an embodiment of the present invention;

[0073] Figure 20A-20B Shows a decrease Fig.19D the diameter of the preset annulus of the catheter;

[0074] Figure 21A-Figure 21C The articulation of a catheter shaft according to an embodiment of the present invention is shown;

[0075] Figure 22A-22B Components of the intermediate section of the catheter are shown;

[0076] Fig.23A A perspective view showing a handle for an ablation catheter according to an embodiment of the present invention;

[0077] Fig. 23B Shows Fig.23A a partial perspective view of the handle shown with the exterior removed;

[0078] Fig.24 is a perspective view of another embodiment of a cryoablation catheter having an internal stylet;

[0079] Figure 25A-Figure 25C is corresponding to Fig.24 A cross-sectional view of different embodiments of the present invention along line 25-25;

[0080] Fig.26 yes Fig.25A An enlarged view of the multi-layer cryogen delivery / return tube is shown;

[0081] Fig.27A yes Fig.24A perspective view of a cryoablation catheter is depicted with an internal stylet inserted;

[0082] Fig.27B yes Fig.24 A perspective view of a cryoablation catheter is depicted with an internal stylet inserted and the flexible distal ablation portion of the ablation shaft / cannula transitioning into the curved configuration of the stylet;

[0083] Figure 28A-28C is corresponding to Fig.27A A cross-sectional view of various embodiments of the present invention taken along line 28-28;

[0084] Fig.29 Sample shapes of pass needles are depicted;

[0085] Fig.30 Depicting a stylet having multiple flexible portions along its length in accordance with an embodiment of the present invention;

[0086] Fig.31A Depicted is a method of changing the flexibility of a portion of a stylet according to an embodiment of the present invention;

[0087] Fig.31B Describes an embodiment of the present invention Fig.31A View in Fig.31B ;

[0088] Fig.32A Depicted is a method of changing the flexibility of a portion of a stylet according to an embodiment of the present invention;

[0089] Fig.32B Depicted is a method of changing the flexibility of a portion of a stylet according to an embodiment of the present invention;

[0090] Fig.32C Depicted is a method of changing the flexibility of a portion of a stylet according to an embodiment of the present invention;

[0091] Fig.33 is a diagram of the location of various lesions and a heart according to an embodiment of the present invention;

[0092] Fig.34 is a diagrammatic representation of an embodiment of an intravascular catheter entering the heart;

[0093] Figure 35-Figure 36 is an illustration of a process of placing a distal segment of a cryoablation catheter against an endocardial wall within a left atrium, defining a left superior pulmonary vein entrance and a left inferior pulmonary vein entrance, in accordance with an embodiment of the present invention;

[0094] Figure 37-Figure 38is a schematic diagram of a process of placing a distal segment of a cryoablation catheter against the endocardial wall within the left atrium, defining the entrances of the right superior and inferior pulmonary veins, in accordance with an embodiment of the present invention.

[0095] Figure 39-40 A method for creating a box-shaped lesion according to an embodiment of the present invention is illustrated, wherein the drawing depicts the left atrium viewed from the back of a patient;

[0096] Fig.41 is a flow chart illustrating a method of creating a box-shaped lesion in the left atrium surrounding a plurality of PVs according to an embodiment of the present invention;

[0097] Fig.42 is an illustration of the heart showing the electrical activity of the mitral valve;

[0098] Fig.43A depicts the formation of a lesion that interrupts mitral valve electrical activity according to an embodiment of the present invention;

[0099] Fig.43B depicts the formation of a lesion that interrupts mitral valve electrical activity according to an embodiment of the present invention;

[0100] Fig.44 is a flow chart illustrating a method of creating a box-shaped lesion in the left atrium that surrounds multiple PVs and interrupts mitral valve electrical activity in accordance with an embodiment of the present invention; and

[0101] Fig.45 Depicted is the creation of a lesion that interrupts electrical activity in the right atrium in accordance with an embodiment of the present invention.

[0102] Detailed Description

[0103] It should be understood that, since various changes or modifications can be made to the embodiments of the invention described and equivalents can be replaced without departing from the spirit and scope of the embodiments of the invention, the embodiments of the invention described herein are not limited to the specific variations set forth herein. It will be apparent to those skilled in the art after reading this disclosure that each of the various embodiments described and illustrated herein has discrete components and features that can be easily separated or combined with the features of any of the other several embodiments without departing from the scope or spirit of the embodiments of the invention. In addition, many modifications may be made to adapt specific situations, materials, compositions of matter, processes, process actions or steps to the purpose, spirit or scope of the embodiments of the invention. All such modifications are intended to fall within the scope of the claims set forth herein.

[0104] In addition, although the methods may be depicted in the drawings or described in the specification in a particular order, these methods do not need to be performed in the particular order shown or in sequence, and all methods do not need to be performed to obtain the desired results. Other methods that are not depicted or described may be incorporated into the example methods and processes. For example, one or more additional methods may be performed before, after, at the same time, or during any method described. In addition, in other embodiments, these methods may be rearranged or reordered. Moreover, the separation of various system components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and should be understood as generally being able to integrate the described components and systems together in a single product or packaged into multiple products. In addition, other embodiments are within the scope of this disclosure.

[0105] Unless otherwise specifically stated or understood otherwise in the context in which it is used, conditional terms such as "can," "could," "might," or "may" are generally intended to express that certain embodiments include or exclude certain features, elements, and / or steps. Thus, such conditional terms are generally not intended to imply in any way that features, elements, and / or steps are required for one or more embodiments.

[0106] Unless specifically stated otherwise, linking language such as the phrase "at least one of X, Y, and Z" is generally understood in the context in which it is used to convey that an item, term, etc. can be X, Y, or Z. Thus, such linking language is generally not intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to be present.

[0107] Reference to a single item includes the possibility that there are a plurality of the same items. More specifically, as used herein and in the appended claims, the singular forms "a," "an," "said," and "the" include plural referents unless the context clearly indicates otherwise. Note also that claims may be designed to exclude any optional elements. This statement is intended to serve as antecedent basis for the use of such exclusive terms as "only," "only," and similar terms in connection with the enumeration of claim elements, or for the use of a "negative" limitation.

[0108] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, if an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0109] It will also be understood that although the terms first, second, etc. may be used to describe various elements herein, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, a first element may be referred to as a second element without departing from the teachings of the present invention.

[0110] The degree language used herein, such as the terms "approximately", "about", "roughly" and "substantially", represents a value, amount or characteristic close to the value, amount or characteristic, which still performs the desired function or achieves the desired result. For example, the terms "approximately", "about", "roughly" and "substantially" can refer to an amount that is less than or equal to 10% of the amount, less than or equal to 5% of the amount, less than or equal to 1% of the amount, less than or equal to 0.1% of the amount, and less than or equal to 0.01% of the amount. If the amount is 0 (e.g., nothing, nothing), the above range can be a specific range and is not within a specific percentage of the value. In addition, the numerical range includes the numbers that define the range, and any single value provided herein can be used as the endpoint of the range including other single values ​​provided herein. For example, a set of values ​​such as 1, 2, 3, 8, 9 and 10 is also a disclosure of the numerical range of 1-10, 1-8, 3-9, etc.

[0111] Some embodiments have been described in conjunction with the accompanying drawings. The drawings are drawn to scale, but such scale should not be limiting, as dimensions and ratios other than those shown are contemplated and are within the scope of the disclosed invention. Distances, angles, etc. are merely illustrative and do not necessarily have an exact relationship to the actual size and layout of the device shown. Components may be added, removed, and / or rearranged. In addition, any specific features, aspects, methods, performances, characteristics, qualities, attributes, elements, etc. disclosed herein in conjunction with the various embodiments may be used in all other embodiments set forth herein. In addition, it will be appreciated that any method described herein may be practiced using any device suitable for performing the steps.

[0112] Although multiple embodiments and variations thereof have been described in detail, other modifications and methods of using them are obvious to those skilled in the art. Therefore, it should be understood that various applications, modifications, materials and substitutions may be equivalent without departing from the unique and creative disclosure or scope of the claims herein.

[0113] All prior subject matter mentioned herein (e.g., publications, patents, patent applications, and hardware) is incorporated herein by reference in its entirety, except to the extent that the prior subject matter mentioned may conflict with the subject matter of the present invention (in which case the content presented herein controls).

[0114] Embodiments of the present invention utilize a thermodynamic process using a cryogen that provides cooling without experiencing the phenomenon of vapor lock.

[0115] Refrigerant Phase Diagram and Near Critical Point

[0116] This application uses phase diagrams to illustrate various thermodynamic processes. Figure 1 An example phase diagram is shown in FIG. The phase diagram includes axes corresponding to pressure P and temperature T, and a phase line 102 that depicts the locus of all (P, T) points where liquid and gas coexist. For (P, T) values ​​to the left of the phase line 102, the cryogen is in the liquid state, which is typically obtained at higher pressures and lower temperatures, while (P, T) values ​​to the right of the phase line 102 define a region where the cryogen is in the gaseous state, which is typically obtained at lower pressures and higher temperatures. The phase line 102 ends abruptly in a single point called a critical point 104. In the example of nitrogen N2, the critical point is at P c =3.396MPa and T c =-147.15℃.

[0117] When fluid has both the liquid phase and the gas phase that exist during the gradual increase of pressure, the system moves upward along the liquid-gas phase line 102. In the example of N2, the liquid under low pressure is denser than the gas phase up to two hundred times. The continuous increase of pressure causes the liquid density to reduce and the gas phase density to increase, until the liquid density and the gas phase density are only equal at the critical point 104 places. The difference between liquid and gas disappears at the critical point 104 places. Therefore, when cryogen flows under the conditions around the critical point defined as "near critical condition" herein, the obstruction (" vapor plug ") of the forward flow caused by the gas expansion before the liquid cryogen is avoided. The factors that allow the greater deviation from the critical point while maintaining functional flow include the greater speed of cryogen flow, the greater diameter of the flow cavity and the lower heat load based on the heat exchanger or the freezing treatment zone.

[0118] As the critical point is approached from below, the vapor phase density increases and the liquid phase density decreases until exactly at the critical point, where the densities of the two phases are exactly equal. Above the critical point, the distinction between the liquid and vapor phases disappears, leaving only a single supercritical phase where the fluid has the properties of both a liquid and a gas (i.e., a dense fluid without surface tension can flow without friction).

[0119] The van der Waals thermodynamic equation of state is a well-known equation describing gases and liquids:

[0120] (p+3 / v 2 )(3v-1)=8t[Equation 1]

[0121] Where p = P / P c , v=V / V c , and t = T / T c , and P c 、V c and Tc They are critical pressure, critical molar volume and critical temperature respectively.

[0122] The variables v, p, and t are often referred to as "comparative molar volume," "comparative pressure," and "comparative temperature," respectively. Thus, any two substances having the same values ​​of p, v, and t are in the same fluid thermodynamic state near their critical points. Equation 1 is thus said to embody the "law of corresponding states." This is more fully described in Introduction to Phase Transitions and Critical Phenomena by H.E. Stanley (Oxford University Scientific Publications, 1971), the entire disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0123] In an embodiment of the present invention, the comparative pressure p is fixed at a constant value of about one, and therefore at a fixed physical pressure near the critical pressure, while the comparative temperature t varies with the thermal load applied to the device. If the comparative pressure p is a constant set by system engineering, then the comparative molar volume v is an exact function of the comparative temperature t.

[0124] In other embodiments of the invention, the operating pressure p may be adjusted so that during changes in the temperature t of the device, v remains below a certain maximum value at which a vapor lock condition would result. It is generally desirable to keep p at a minimum value at which it is reliable, since increasing the pressure to achieve higher values ​​of p may involve the use of more complex and more expensive compressors, resulting in more expensive purchase and maintenance of the entire device support system and lower overall cooling efficiency.

[0125] The condition for v depends in a complex way on the volume flow rate dV / dt, the heat capacity of the liquid and vapor phases, and transport properties such as thermal conductivity, viscosity, etc. in both liquid and vapor. The exact relationship is not obtained algebraically in a closed form, but can be determined numerically by integrating the model equations describing the mass and heat transport within the cooling device. Conceptually, vapor lock occurs when the heating rate of the tip (or other device structures used to transport refrigerants and cool tissues) produces a vapor phase. The cooling capacity of the vapor phase, which is proportional to the flow rate of the vapor multiplied by the heat capacity of the vapor divided by the molar volume of the vapor, cannot keep up with the heating rate of the tip. When this happens, more and more vapor phases are formed in order to absorb the excess heat that is converted from the liquid phase to vapor in the refrigerant flow. This forms an escape condition for the liquid to transform into the vapor phase to fill the tip, and all refrigerant flows are effectively stopped due to the large pressure of the vapor phase when the heat flowing into the tip rapidly increases its temperature and pressure. This condition is called "vapor lock".

[0126] According to one embodiment of the present invention, the molar volumes of the liquid phase and the vapor phase are substantially the same. The cooling capacity is at the critical point, and the cooling system avoids vapor lock. In addition, the device can also avoid vapor lock under conditions slightly below the critical point.

[0127] Cryoablation system

[0128] Figure 2 A schematic diagram of a structural arrangement for a cryogenic system in one embodiment is provided, and Figure 3 Provides instructions when Figure 2 Phase diagram of the thermodynamic path taken by the cryogen when the system is operated. The circled numerical identifiers in the two figures correspond so that Figure 2 The physical location of reaching the operating point determined along the thermodynamic path is indicated in . The following description therefore sometimes refers to both the physical and thermodynamic aspects of the cooling flow. Figure 2 The structure diagram and Figure 3 Phase diagram.

[0129] For illustration purposes, Figure 2 and Figure 3 Specific reference is made to nitrogen cryogen, but this is not intended to be limiting. Embodiments of the present invention may more generally be used with any suitable cryogen, such as argon, neon, helium, hydrogen, and oxygen.

[0130] exist Figure 3 , the liquid-gas phase line is identified by reference numeral 256 and the thermodynamic path followed by the cryogen is identified by reference numeral 258 .

[0131] The low temperature generator 246 is used to generate a pressure exceeding the critical point pressure P of the cryogen at its outlet. c Supply refrigerant at pressure of Figure 2 and Figure 3 Reference number ①. Although the pressure is close to the critical point pressure P c is favorable, but cooling cycles can usually have a phase diagram with a value above or slightly below P c When the initial pressure approaches the critical point pressure P c The cooling efficiency of the processes described herein is generally greater when the pressure is higher, so that there may be an increased energy requirement to achieve the desired flow at higher pressures. Therefore, embodiments may sometimes include various higher upper boundary pressures, but generally begin near the critical point, such as at 0.8 and 1.2 times P c and in one embodiment, between about 0.85 times P c Start at.

[0132] As used herein, the term "near critical" refers to near the liquid-vapor critical point. The use of this term is equivalent to "near critical point" and it is a region where the liquid-vapor system is sufficiently close to the critical point, where the dynamic viscosity of the fluid is close to the dynamic viscosity of a normal gas and much less than the dynamic viscosity of a liquid; in addition, at the same time the density of the fluid is close to the density of a normal liquid state. The heat capacity of a near-critical fluid is even greater than the heat capacity of its liquid phase. The combination of gas-like viscosity, liquid-like density and very large heat capacity makes near-critical fluids very effective coolants. Reference to the near-critical point refers to such a region where the liquid-vapor system is sufficiently close to the critical point so that the fluctuations of the liquid and vapor phases are large enough to form a great increase in heat capacity above its background value. The near-critical temperature is a temperature within ±10% of the critical point temperature. The near-critical pressure is between 0.8 and 1.2 times the critical point pressure.

[0133] Reference again Figure 2 , the cryogen flows through a tube, at least a portion of which is surrounded by a reservoir 240 of cryogen in a liquid state, reducing its temperature without substantially changing its pressure. Figure 2 In FIG. 2 , the reservoir is shown as liquid N2, with a heat exchanger 242 disposed within the reservoir 240 to extract heat from the flowing cryogen. Outside the reservoir 240, thermal insulation may be disposed around the tube to prevent unwanted warming of the cryogen as it flows from the cryogen generator 246. At point ②, after being cooled by thermal contact with the liquid cryogen, the cryogen has a lower temperature but is substantially at the initial pressure. In some cases, such as in Figure 3 There may be a pressure change, indicated in the form of a slight pressure drop, provided that the pressure does not substantially drop to the critical pressure P c below, i.e. not below a certain minimum pressure. Figure 3 In the example shown in , the temperature drop as a result of flowing through the liquid cryogen is approximately 50°C.

[0134] The refrigerant is then supplied to equipment for use in cryogenic applications. Figure 2 In the exemplary embodiment shown, cryogen is provided to an inlet 236 of a catheter 224, which may be used, for example, in a medical cryogenic intravascular application, but this is not required.

[0135] Indeed, the form of a medical device can vary widely and include, but is not limited to, instruments, implements, catheters, equipment, tools, devices, and probes, whether such probes are short and rigid or long and flexible and whether they are used for open, minimally invasive, non-invasive, manual, or robotic surgery.

[0136] In an embodiment, the refrigerant may be introduced through the proximal portion of the catheter, continuing along the flexible middle section of the catheter and into the distal treatment section of the catheter. Figure 2 and Figure 3 When the cryoablation treatment area 228 is delivered through the catheter between the numbers ② and ③ in FIG. 224 , there may be a situation where the cryoablation agent moves through the interface with the device (e.g., Figure 2 The cryoablation zone 228 in the cryoablation chamber is a slight change in its pressure and / or temperature. This change can generally show a slight increase in temperature and a slight decrease in pressure. Assuming that the cryogen pressure remains above a determined minimum pressure (and associated conditions), a slight increase in temperature will not significantly affect performance because the cryogen only moves back toward the critical point and does not encounter the liquid-vapor phase line 256, thereby avoiding vapor lock.

[0137] In the described embodiments, components including a check valve 216, a flow impedance, and / or a flow controller may be used to control the flow of cryogen from a cryogen generator 246 through a catheter 224 or other device. The catheter 224 itself may include a vacuum insulator 232 (e.g., a cover or sleeve) along its length and may have a cold cryoablation region 228 for cryogenic applications. Unlike a Joule-Thomson probe, in which the pressure of the working cryogen changes significantly at the tip of the probe, these embodiments of the present invention provide relatively small changes in pressure throughout the entire device. Thus, at point ④, the temperature of the cryogen has risen to approximately ambient temperature, but the pressure remains elevated. As the cryogen is delivered through the catheter, the pressure is maintained above or close to the critical point pressure P c , vapor lock can be avoided.

[0138] The cryogen pressure returns to ambient pressure at point ⑤. The cryogen can then be discharged through the exhaust port 204 under substantially ambient conditions.

[0139] Examples of cryoablation systems, components thereof, and various arrangements thereof are described in the following commonly assigned U.S. patents and U.S. patent applications: U.S. patent application Ser. No. 10 / 757,768, filed Jan. 14, 2004, by Peter J. Littrup et al., which issued as U.S. Pat. No. 7,410,484 on Aug. 12, 2008, and entitled “CRYOTHERAPY PROBE”; U.S. patent application Ser. No. 10 / 757,769, filed Jan. 14, 2004, by Peter J. Littrup et al., which issued as U.S. Pat. No. 7,083,612 on Aug. 1, 2006, and entitled “CRYOTHERAPY SYSTEM”; U.S. Patent Application No. 10 / 952,531, filed on September 27, 2004 by Peter J. Littrup et al., which issued on September 25, 2007 as U.S. Patent No. 7,273,479, entitled “METHODS AND SYSTEMS FOR CRYOGENIC COOLING”; U.S. Patent Application No. 11 / 447,356, filed on June 6, 2006 by Peter Littrup et al., which issued on March 24, 2009 as U.S. Patent No. 7,507,233, entitled “CRYOTHERAPY SYSTEM”; U.S. Patent Application No. 11 / 846,226, filed on August 28, 2007 by Peter Littrup et al., which issued on April 12, 2011 as U.S. Patent No. 7,921,657, entitled “METHODS AND SYSTEMS FOR CRYOGENICCOOLING”; U.S. Patent Application No. 12 / 018,403, filed on January 23, 2008 by Peter Littrup et al., which issued on November 26, 2013 as U.S. Patent No. 8,591,503, entitled “CRYOTHERAPY PROBE”; U.S. Patent Application No. 13 / 046,274, filed on March 11, 2011 by Peter Littrup et al., which issued on March 5, 2013 as U.S. Patent No. 8,387,402, entitled “METHODS AND SYSTEMS FOR CRYOGENICCOOLING”; U.S. Patent Application No. 14 / 087,947, filed on November 22, 2013 by Peter Littrup et al., which is pending and entitled “CRYOTHERAPY PROBE”;U.S. Patent Application No. 12 / 744,001, filed on July 29, 2010 by Alexei Babkin et al., and issued on June 3, 2014 as U.S. Patent No. 8,740,891, entitled “FLEXIBLE MULTI-TUBULAR CRYOPROBE”; U.S. Patent Application No. 12 / 744,033, filed on July 29, 2010 by Alexei Babkin et al., and issued on June 3, 2014 as U.S. Patent No. 8,740,892, entitled “EXPANDABLE MULTI-TUBULAR CRYOPROBE”; and U.S. Patent No. 12 / 744,033, filed on July 29, 2010 by Alexei Babkin et al., and issued on June 3, 2014 as U.S. Patent No. 8,740,892, entitled “EXPANDABLE MULTI-TUBULAR CRYOPROBE”; and U.S. Patent No. 12 / 744,033, filed on September 22, 2014 by Alexei Babkin et al., entitled “ENDOVASCULAR NEAR CRITICAL FLUID BASED CRYOABLATIONCATHETER AND RELATED METHODS”, the contents of each of the above US patents / applications are hereby incorporated by reference in their entirety for all purposes.;

[0140] A method for cooling a target tissue using Figure 4 A flow chart illustrating the flow of the cryogens according to Figure 3 In the embodiment of the present invention, the cryogen is heated to 100 ℃ and the temperature is 400 ℃.In ...

[0141] Additional cooling cryogen is provided to the cryogenic application equipment that can be used for the cooling application at block 322 at block 318. The cooling application can include freezing (chilling) and / or freezing (freezing) according to whether the target uses the cooling application freezing. As a result of the cryogen application, the temperature of the cryogen increases, and the cryogen heated at block 326 flows to the control console. Although there can be some changes, the cryogen pressure is usually maintained above the critical point pressure throughout blocks 310-326; The main change in the thermodynamic properties of the cryogen at these stages is its temperature. At block 330, the pressure of the heated cryogen is then allowed to drop to ambient pressure, so that the cryogen can be discharged or recycled at block 334. In other embodiments, the remaining pressurized cryogen at block 326 can also be returned to block 310 along the path to recirculate the cryogen instead of discharging the cryogen at ambient pressure.

[0142] Cryoablation catheter

[0143] Embodiments of the cryoablation device of the present invention may have a variety of configurations. For example, one embodiment of the present invention is a flexible catheter 400 as shown in FIG5A. The catheter 400 includes a proximally disposed housing or connector 410 adapted for fluid connection to a fluid source (not shown).

[0144] A plurality of fluid transfer tubes 420 are shown extending from the connector 410. The tubes include a set of input fluid transfer tubes 422 for receiving input flow from the connector and a set of output fluid transfer tubes 424 for exhausting flow from the connector 410.

[0145] In an embodiment, each of the fluid transfer tubes is formed of a material that remains flexible in a full range of temperatures from -200°C to ambient temperature. In an embodiment, the fluid transfer tube 420 is formed of annealed stainless steel or a polymer such as polyimide. In this configuration, the material can remain flexible at near critical temperatures. In an embodiment, each fluid transfer tube has an inner diameter in a range between about 0.1 mm and 1 mm (preferably between about 0.2 mm and 0.5 mm). Each fluid transfer tube may have a wall thickness in a range between about 0.01 mm and 0.3 mm (preferably between about 0.02 mm and 0.1 mm).

[0146] End cap 440 is positioned at the end of the fluid transfer tube to provide fluid transfer from the input fluid transfer tube to the output fluid transfer tube. End cap 440 is shown as having an atraumatic tip. End cap 440 can be any suitable element for providing fluid transfer from the input fluid transfer tube to the output fluid transfer tube. For example, end cap 440 can define an inner chamber, cavity or channel for fluid connection tubes 422, 424.

[0147] 5B, an outer sheath 430 is shown surrounding the tube bundle 420. The outer sheath serves to hold the tubes in the tubular arrangement and protect the structure from penetration or damage by foreign objects and obstructions.

[0148] A temperature sensor 432 is shown on the surface of the distal segment. The temperature sensor may be a thermocouple to sense the temperature corresponding to the adjacent tissue and send a signal back to the console via a wire in the tube bundle for processing. The temperature sensor may be placed elsewhere along the shaft or within one or more fluid transfer tubes to determine the temperature difference between inflow and outflow.

[0149] There are many configurations for the arrangement of the tubes. In an embodiment, the fluid transfer tubes are formed by a circular array, wherein the set of input fluid transfer tubes includes at least one input fluid transfer tube 422 defining a central region of a circle, and wherein the set of output fluid transfer tubes 424 includes a plurality of output fluid transfer tubes spaced around the central region in a circular pattern. In the configuration shown in FIG. 5B , the fluid transfer tubes 422, 424 fall within this class of embodiments.

[0150] During operation, a cryogen / freezing fluid is supplied from a suitable cryogen source at a temperature close to -200°C through a supply line to the conduit, the cryogen circulates through the multi-tubular freezing zone provided by the exposed fluid transfer tubes, and returns to the connector. The cryogen flows into the freezing zone through the input fluid transfer tube 422 and flows out of the freezing zone through the output fluid transfer tube 424.

[0151] In an embodiment, the nitrogen flow does not form gaseous bubbles in the small diameter tubes under any heat load so as not to produce vapor locks that restrict flow and cooling capacity. By operating at near-critical conditions for at least the initial period of energy application, vapor locks are eliminated as the distinction between the liquid phase and the vapor phase disappears. After initial operation at near-critical conditions (e.g., for nitrogen, at a temperature close to the critical temperature of -147.15°C and at a pressure close to the critical pressure of 3.396 MPa), the operating pressure can be reduced as disclosed and described in commonly assigned U.S. Patent Application No. 14 / 919,681, entitled "PRESSURE MODULATEDCRYOABLATION SYSTEM AND RELATED METHODS," filed by Alexei Babkin on October 21, 2015, the contents of which are incorporated herein by reference in their entirety for all purposes.

[0152] A multi-tube design may be preferred over a single-tube design because the additional tubes can significantly increase the heat exchange area between the cryogen and the tissue. Depending on the number of tubes used, the cryoinstrument can increase the contact area several times over previous designs with a single shaft / tube of similar size diameter. However, embodiments of the present invention are not intended to be limited to single or multi-tube designs unless specifically stated in the appended claims.

[0153] Cryoablation console

[0154] Figure 6 A cryoablation system 950 having a cart or console 960 and a cryoablation catheter 900 detachably connected to the console via a flexible elongated tube 910 is shown. Figure 7 The cryoablation catheter 900 described in greater detail includes one or more fluid delivery tubes to remove heat from tissue.

[0155] The console 960 may include or house various components (not shown), such as a generator, a controller, a tank, a valve, a pump, etc. For the convenience of user operation, a computer 970 and a display 980 are provided on the Figure 6 97 is shown as being located on top of the cart. The computer may include a controller, a timer, or communicate with an external controller to drive components of the cryoablation system (e.g., a pump, a valve, or a generator). Input devices such as a mouse 972 and a keyboard 974 may be provided to allow a user to input data and control the cryoablation device.

[0156] In an embodiment, computer 970 is configured or programmed to control cryogen flow rate, pressure, and temperature as described herein. Target values ​​and real-time measurements may be sent to and displayed on display 980 .

[0157] Figure 7 An enlarged view of the distal segment 900 of the cryoablation device is shown. The distal segment 900 is similar to the above-described design, except that the treatment area 914 includes a flexible protective covering 924. The covering is used to contain leakage of cryogen in the event of a rupture of one of the fluid delivery tubes. Although leakage is undesirable or unintended in either of the fluid delivery tubes, the protective covering provides an additional or redundant barrier that the cryogen will have to penetrate in order to flow out of the catheter during the procedure. In an embodiment, the protective covering can be formed of metal.

[0158] Additionally, a thermally conductive liquid may be disposed within the space or gap between the delivery tube and the inner surface of the cover to enhance thermal cooling efficiency of the device during treatment. In an embodiment, the thermally conductive liquid is water.

[0159] The cover 924 is shown to be tubular or cylindrical and terminates at the distal tip 912. As described herein, the cooling zone 914 includes a plurality of fluid delivery tubes and fluid return tubes to deliver cooling fluid through the treatment zone 914, resulting in heat being transferred / removed from the target tissue. In an embodiment, the refrigerant is delivered through the tube bundle under physical conditions adjacent to the critical point of the fluid in the phase diagram. Among other things, the cover helps contain the cooling fluid and prevent it from escaping from the catheter in the event of a leak forming in one of the delivery tubes.

[0160] Despite Figure 6-7 The device may be provided with or without a protective cover and is used to cool target tissue.

[0161] Tube within a tube

[0162] Figure 8 A partial view of a cryoablation catheter 1010 according to another embodiment of the present invention is shown, the cryoablation catheter 1010 having a protective device that mitigates leakage in the event that cooling fluid / cryogen escapes from the cryogen delivery tube described above. In particular, the catheter 1010 includes a plurality of flexible multi-layer cryoenergy transmission tubes or a bundle 1012 of flexible multi-layer cryoenergy transmission tubes, each of which includes two tubes in a coaxial arrangement, i.e., a tube in a tube.

[0163] Fig.9A Shown along Figure 8 9A-9A of FIG. 10. A bundle 1012 of multilayer tubes is shown with fluid delivery tubes 1014 and fluid return tubes 1015 assembled in a parallel arrangement. The bundle 1012 is shown with 12 tubes / lines, including four (4) fluid return tubes 1015a-1015d and eight (8) fluid delivery tubes 1014a-1014h. The fluid delivery tubes 1014a-1014h form a perimeter around the fluid return tubes 1015a-1015d. This arrangement ensures that the cooler delivery fluid / refrigerant is adjacent to the tissue to be ablated / frozen and the warmer return fluid / refrigerant is isolated from the tissue to be ablated / frozen.

[0164] Fig. 9B Shows Fig.9A FIG. 1 is an enlarged cross-sectional view of a fluid delivery tube 1014d of FIG. 1. The first tube or inner tube 1013 is shown as being coaxially surrounded by the second tube or outer tube 1018. As described herein, the space or gap 1020 between the outer surface of the inner tube 1013 and the inner surface of the outer tube 1018 can be filled with a thermally conductive medium 1021. In an embodiment, the gap 1020 has an annular shape. All of the fluid delivery tubes 1014 and the fluid return tube 1015 can have similar tubes within the tube structure.

[0165] During use, if the cooling fluid 1016 leaks or the inner tube 1013 ruptures, the cooling fluid 1016 is contained within the gap 1020 between the inner tube 1013 and the outer tube 1018. This tube-in-tube feature adds an additional safety element to the device because any leaking fluid / refrigerant 1016 is confined within the catheter and prevented from entering the patient's body. In some embodiments, a pressure sensor / device or pressure gauge can be incorporated to monitor the pressure of the thermally conductive medium 1021 in the gap 1020. Therefore, if the fluid / refrigerant 1016 breaks through the inner tube 1013 and leaks into the gap 1020, the pressure in the gap 1020 will increase, and therefore the pressure of the conductive medium 1021 will also increase. If the pressure change exceeds a threshold limit, the system can be programmed to stop ablation, thereby preventing potential harm to the patient and / or notifying the user / doctor of the pressure change.

[0166] Inner tube 1013 may be prepared or fabricated from materials as described herein in connection with other flexible tubes used to transport cooling fluids.

[0167] As disclosed herein, the material of the outer tube 1018 should also be flexible to enable elastic deflection of the distal treatment segment, thereby allowing the distal treatment segment to change its shape. In some embodiments, the outer tube is non-inflatable, non-expandable, and non-expandable, such that its size and shape are not substantially affected by the presence of the thermally conductive medium 1021 contained therein. Non-limiting exemplary materials for the outer tube 1018 include polymers and metals or alloys. Examples of materials for the outer tube 1018 are nitinol or polyimide.

[0168] The number of tubes forming tubular bundle 1012 may vary widely. In some embodiments, tubular bundle 1012 includes 5-15 tubes, more preferably 8-12 tubes, including fluid delivery tubes 1014 and fluid return tubes 1015.

[0169] The cross-sectional profile of the tube bundle 1012 may also vary. Fig.9A A generally circular profile is shown, however, in embodiments, the profile may be rectangular, square, cross or t-shaped, annular or circumferential, or another shaped profile including some of the arrangements described above. The tubes may also be braided, woven, twisted or otherwise entangled together, as shown in FIG. 9, FIG. 10, and FIG. 11 of commonly assigned U.S. Patent Application No. 14 / 915,632, filed on September 22, 2014 by Alexei Babkin et al., entitled “ENDOVASCULAR NEARCRITICAL FLUID BASED CRYOABLATION CATHETER AND RELATED METHODS”. Fig.14 and Fig.16 depicted, the entire contents of which are incorporated herein by reference for all purposes.

[0170] The diameter of the frozen segment or tubular bundle can vary. In an embodiment, the diameter of the bundle ranges from about 1-3 mm, and preferably about 2 mm.

[0171] Fig. 9C A cross section of a cryoablation catheter is shown having another tubular arrangement 1017. Eight (8) tubular elements (1019a-1019d and 1023a-1023d) are spaced or distributed circumferentially around a core element 1025. Preferably, as shown, the fluid delivery elements / tubes (1019a-1019d) and fluid return elements / tubes (1023a-1023d) alternate along the circumference of the catheter.

[0172] As reference Fig. 9B As described, each inner tubular element (eg, 1019a) includes an outer tubular element (eg, 1027a) coaxially surrounding the inner tubular element, thereby creating a space or gap that can be filled with a thermally conductive medium / fluid.

[0173] Manipulators, sensors and other functional elements may be incorporated into the catheter. In an embodiment, the manipulators are incorporated into the mechanical core, e.g. Fig. 9C The mechanical movement 1025 is shown.

[0174] Fig. 10A Show Figure 8 An enlarged cross-sectional view of the conduit at detail 10A illustrates the end portion 1040 of the middle section of the conduit 1010 where the tube bundle 1012 is fluidly connected.

[0175] Fig. 10B An exploded view of the intermediate section 1040 of the catheter and the proximal section of the tube bundle 1012 is shown. The tube bundle 1012 having inner tubular elements 1013a-1013d extending beyond the outer tubular elements / coverings 1018a-1018d extending beyond the fluid delivery line 1014 can be inserted into the intermediate section 1040 of the catheter.

[0176] refer to Figures 10A-10B , the fluid delivery line 1014 is shown bundled together and plugged / coupled to the main line 1032. Adhesive plugs 1042 or seals, gaskets or stops, etc. may be applied to help and ensure fluid sealing between the pipe components. Cooling power fluid (CPF) is delivered from the fluid delivery main line 1032 to the fluid return line 1014.

[0177] The proximal ends of the outer tubular elements / covers 1018a-1018d offset from the proximal ends of the inner tubular elements 1013a-1013d are shown inserted into the middle section 1040 of the catheter so that the thermally conductive fluid (TCF) within the lumen 1050 can fill the gaps 1020 ( Fig. 9B ). Adhesive plug 1044 (welding or bonding) may be applied to promote a fluid-tight and strong connection. As is known to those skilled in the art, press fit, heating and other manufacturing techniques may be applied to connect the components.

[0178] Fig.11 Another cryoablation catheter 500 is shown, which includes a distal treatment segment 510, a handle 520, and an umbilical cord 530. The proximal end of the umbilical cord 530 terminates in a connector 540, which plugs into a receptacle port 560 on a console 550.

[0179] One or more auxiliary connector lines 570 are shown extending proximally from handle 520. Tubular lines 570 may be used to provide various functions including, but not limited to, (a) irrigation; (b) vacuum; (c) thermally conductive fluids as described above; and / or (d) temperature and pressure sensor conductors.

[0180] The catheter 500 is also shown as having an electrical connector 580 extending proximally from the handle 520. The electrical connector 580 can be coupled to an EP recording system for analyzing electrical information detected in the distal treatment segment 510. Examples of systems for analyzing electrical activity include, but are not limited to, the GE Healthcare CardioLab II EP Recording System manufactured by GE Healthcare and the LabSystem PRO EP Recording System manufactured by Boston Scientific Inc. (Marlborough, Massachusetts). The recorded electrical activity can also be used to assess or verify continued contact with target tissue, as described in commonly assigned International Patent Application No. PCT / US16 / 51954, entitled “TISSUE CONTACT VERIFICATION SYSTEM,” filed by Alexei Babkin et al. on September 15, 2016, the entire contents of which are incorporated herein by reference for all purposes.

[0181] Fig.12An enlarged view of a portion of the distal segment 510 of the catheter 500 is shown. Ring electrodes 602, 604 are circumferentially arranged around the shaft 606. Although two electrodes are shown, there may be more or fewer electrodes on the shaft for sensing electrical activity. In an embodiment, up to 12 electrodes are provided on the shaft. In one embodiment, 8 electrodes are spaced axially along the shaft 606.

[0182] Fig.13 It is taken along line 13-13 Fig.12 A cross section of a catheter is shown in . The catheter shaft is shown having a mechanical core 620 extending along a central axis, and a plurality of energy delivery tube configurations 630 extending in parallel and disposed circumferentially about the mechanical core.

[0183] Each tube structure 630 is shown as having a combined Figure 8 -9 A double layer as described above and a layer of heat conducting liquid disposed therebetween.

[0184] Tubular line 624 is shown for housing wires 626 for various sensors described herein.

[0185] The mechanical core 620 can be configured to provide a preset shape to the distal treatment section of the catheter. Fig.13 The mechanical core includes a metal tubular member 622 having a preset shape. The preset shape matches the target anatomical structure to continuously contact the target anatomical structure. An exemplary material of the preset tubular element 622 is Nitinol. Fig.13 Also shown is an outer layer or covering concentrically surrounding the nitinol tube. The outer covering can be a flexible polymer, such as PET. The inner PET layer 620 and the outer shaft layer 606 together form a fluid-tight annular chamber to accommodate the plurality of tubular structures 630.

[0186] refer to Figure 14-15 , the catheter 608 is shown deployed from the outer sheath 642. Initially, the distal segment 606 of the catheter is disposed within the lumen of the outer sheath 642 and is restrained from assuming its preset shape. The distal segment 606 and the outer sheath 642 move axially relative to each other. For example, the catheter can be ejected from the sheath. Once the catheter is unconstrained, it assumes the shape shown in FIG. Fig.15 Preset shapes shown.

[0187] The mechanical core assembly biases the shape of the distal segment 608 of the catheter, forcing the energy delivery element into a curved shape. In an embodiment, the catheter shape is suitable for creating a lesion in the right atrium for treating atrial flutter. For example, Fig.15The shape shown is a single ring or elliptical shape with a curvature that matches the target area of ​​tissue in the right atrium for treating atrial flutter. Additional devices and methods for treating atrial flutter are described in commonly assigned U.S. Patent Application No. 61 / 981,110, filed April 17, 2014, now International Patent Application No. PCT / US2015 / 024778, filed October 21, 2015, entitled "ENDOVASCULAR NEAR CRITICAL FLUID BASED CRYOABLATION CATHETER HAVING PLURALITY OF PREFORMED TREATMENT SHAPES," the contents of both of which are incorporated herein by reference in their entirety for all purposes.

[0188] Fig.16 Another cryoablation catheter 700 is shown, which includes a distal treatment segment 710, a handle 720, and an umbilical cord 730 terminating in a connector 740. Fig.11 In the described system, connector 740 may be plugged into a socket port on the console.

[0189] Additional wires 742, 744 are shown extending proximally from the handle. The wires 742, 744 provide various functions for the distal treatment segment 710 during the procedure. Example functions include, but are not limited to, temperature, EP recording, pressure, fluid irrigation, source fluid, etc.

[0190] Fig.17 is an enlarged view of the distal segment of the catheter after deployment. The treatment segment is shown as having a generally annular or elliptical shape 714. The intermediate segment 716 is shown as providing a bend or articulation from a central axis 718. This feature helps position the treatment segment in continuous direct contact with tissue. In an embodiment, the shape is configured to produce a complete PVI in the left atrium.

[0191] Fig.18 75 is an enlarged cross-sectional view of a portion of the distal treatment segment. The catheter shaft is shown having a mechanical core 750 extending along a central axis, and a plurality of energy delivery tube structures 752 extending in parallel and circumferentially surrounding the mechanical core. One or more alternate tubular elements 754, 758 may be incorporated into the peripheral space along with the energy delivery elements. The tubular element 754 houses a plurality of electrical conductors to transmit electrical activity from sensors or ring electrodes 756 present on the distal treatment segment. The tubular element 758 may provide a vacuum or fluid to the catheter for various functions described herein.

[0192] The mechanical core 750 is shown extending axially through the treatment segment and includes a plurality of members 760, 762 extending through the distal treatment segment to bias the distal segment into a preset shape, e.g. Fig.17 Specifically, in an embodiment, the mechanical core may include a biasing shape element 760, such as a nitinol wire, and an axially movable control member 762 connected to the distal tip of the treatment segment to adjust the curvature of the preset shape. If desired, the core may include additional cavities 766, 768. The mechanical core is used to shape the distal treatment segment into a first preset ring shape, and can be further adjusted by the control member to continuously contact the target tissue surface.

[0193] Figures 19A-19D The ablation catheter 810 is shown sequentially deployed from a first arcuate shape having a slight bend to a second configuration having a full annular or circular shape 820. This shape is assumed once the catheter treatment segment is freed from the outer sheath 812.

[0194] Figures 20A-20B Shows Fig.19D 800, except that the ring has been adjusted by reducing its diameter ф1. As described herein, a control member extending through the shaft of the distal treatment segment is pulled to reduce the diameter ф1 of the preset ring to a diameter of ф1 as shown in FIG. Fig. 20A The diameter shown is ф2. Fig. 20B shows the adjustment to the ratio Fig. 20A The smaller diameter ring with a diameter of ф3 is shown.

[0195] The diameter ф of the ring can vary. In an embodiment, the diameter of the ring is controlled in the range of 2 cm to 5 cm, and in an embodiment, preferably about 2-3 cm.

[0196] Figures 21A-21C The sequential articulation of the intermediate section 814 of the catheter is shown. The intermediate section 814 is shown with an external support or reinforcement structure 816. In an embodiment, the support layer 816 is a spring or coil.

[0197] Fig.21A The catheter intermediate section 814 is shown to be substantially straight or aligned with the shaft axis.

[0198] Fig. 21B The catheter intermediate section is shown having a slight articulation forming an angle θ1 with the shaft axis.

[0199] Fig. 21C The catheter intermediate section is shown with further articulation θ2 to the shaft axis. As described below, the angle of articulation can be varied and adjusted by the physician. In an embodiment, the angle of articulation is up to 120 degrees, more preferably up to about 90 degrees, to the central shaft axis.

[0200] Figures 22A-22BAn example of a component / structure for an articulated intermediate section is shown. These components include a coil 832, a second pull wire 834, and a spine 836. The pull wire 834 is fixed to a distal position of the intermediate section. Pulling the pull wire causes the coil 832 to deflect or articulate. The spine 836 is shown as being diametrically opposite to the pull wire. The spine is used to bias the direction of catheter bending when the pull wire is retracted, and is used to return the catheter to its straight position when the pull wire is released. In particular, when the pull wire is retracted, the catheter bends toward the pull wire along a plane including the pull wire, the center coil axis, and the spine.

[0201] Various articulated components / structures can be made of a variety of materials. Exemplary materials include, but are not limited to, nitinol, stainless steel, or other materials having the functions described herein. In addition, components can be made of wires, tubular elements, or sheets of stock material. In one embodiment, the coil and spring are integrally formed by a piece of metal alloy. The desired shape can be machined or laser cut to produce ridge and rib elements, allowing for biased articulation. See also U.S. Patent Publication No. 2003 / 0195605, entitled "Cryogenic Catheter with Deflectable Tip," filed by Kovalcheck et al. on May 30, 2003, for further details of a catheter including a spring, a pull wire, and a ridge for controlling deflection.

[0202] Fig.23A A perspective view of a handle 852 of an ablation catheter is shown. A flexible catheter shaft 854 extends from a distal section 856 of the handle. An umbilical cord 858 and various other functional lines and connectors 859 are shown extending proximally from a proximal section 860 of the handle.

[0203] The handle 852 is shown as having an ergonomic design, including a smooth, gently curved mid-section 862 that allows a user to conveniently grip the handle.

[0204] The handle is shown to include a knob 864 that can be rotated relative to the handle body to control the diameter of the deployed ring as described above. An axially movable hub 866 is shown adjacent to the knob. Movement of the hub 866 forward or backward is used to adjust or articulate the axis of the deployment as described above. In addition, the handle can be rotated as a whole to manipulate the catheter in one direction or another. In general, the handle provides a convenient and semi-automatic means to rotate, articulate and control the diameter or size of the deployed structure.

[0205] Fig. 23B Shows Fig.23AA partial perspective view of the handle is shown with the exterior removed for clarity. A section of external threads or teeth 872 is shown. The teeth 872 mate with grooves or threads in the knob 864. These teeth are linked to the first control member described above for changing the shape or diameter of the ring. When the knob is rotated, the pull wire moves simultaneously.

[0206] A slider 874 is also shown in the handle. The slider 874 is coupled to the hub 866 so that movement of the hub causes movement of the slider. As described above, the slider is also linked to a second control member for articulating the catheter shaft. When the outer hub is moved by the physician, the second control member articulates the shaft.

[0207] Although the handle is shown as having a knob, a hub and a slider, the present invention is not limited thereto. The present invention may include other levers, gears, buttons and devices for achieving the above functions.

[0208] Fig.24 Depicted is an ablation catheter 880 according to another embodiment of the present invention. In this embodiment, the ablation catheter 880 includes two main components: (a) an ablation shaft / cannula 881 for delivering ablative energy to a site of interest in a human body; and (b) a stylet 882 that can be inserted into an internal cavity within the ablation shaft / cannula 881. As will be discussed in more detail below, at least a portion of the ablation shaft / cannula 881 is made of a flexible material so that this portion of the ablation shaft / cannula 881 can assume the shape of the stylet 882 inserted therein and constructed of a shape memory alloy. Although the ablation catheter 880 is described herein as being used as a cryoablation catheter that creates lesions by freezing tissue with any suitable cryogen (e.g., but not limited to, nitrogen, argon, neon, helium, hydrogen, and oxygen), in other embodiments, the ablation catheter can be used with other ablation energies, such as radiofrequency, microwave, laser, and high frequency ultrasound (HIFU).

[0209] like Fig.24As depicted, the ablation shaft / cannula 881 includes a handle portion (not shown and may be constructed in accordance with any of the handle embodiments disclosed herein), a first shaft portion 883, a flexible shaft portion 884, a flexible distal ablation portion 885, and a distal ablation tip 886. In some embodiments, the ablation catheter 880 may also include a plurality of electrodes 887 on the flexible distal ablation portion 885, which may be used to detect electrical activity in the target tissue in order to assess or verify continuous contact of the flexible distal ablation portion 885 with the target tissue, as described in commonly assigned International Patent Application No. PCT / US16 / 51954, entitled “TISSUE CONTACTVERIFICATION SYSTEM,” filed by Alexei Babkin et al. on September 15, 2016, the entire contents of which are incorporated herein by reference for all purposes. In some embodiments, the electrode 887 may be included on the distal ablation tip 886. In some embodiments, the first shaft portion 883 may be flexible, semi-flexible, semi-rigid, or rigid. In some embodiments, the first shaft portion 883 is less flexible than the flexible shaft portion 884, however, the first shaft portion 883 is still flexible so that it can be delivered to the target tissue through the body's venous system.

[0210] In some embodiments, the ablation shaft / cannula 881 can include a handle portion, a flexible shaft portion 884, a flexible distal ablation portion 885, and a distal ablation tip 886. That is, the ablation shaft / cannula 881 can be flexible along its entire length.

[0211] Fig.25A Depicted along Fig.24 25-25 in the cross-sectional view of the ablation catheter 881, wherein the needle 882 is not inserted into the ablation shaft / sleeve 881. As can be seen from the cross-sectional view, the ablation shaft / sleeve 881 includes a plurality of multi-layer cryogen delivery tubes / cavities 888 for delivering cryogen to the flexible distal ablation portion 885, and a plurality of multi-layer cryogen return tubes / cavities 889 for delivering cryogen away from the flexible distal ablation portion 885. A plurality of service tubes / cavities 891 are also shown, which may include catheter control wires, electrode wires 892, or any other elements that may be required. The plurality of multi-layer cryogen delivery tubes / cavities 888, the plurality of multi-layer cryogen return tubes / cavities 889, and the plurality of service tubes / cavities 891 are arranged in a circular array around the hollow tube / cavity 890, which is suitable for receiving the needle 882 therein. The hollow tube / cavity 890 extends from the handle to at least the flexible distal ablation portion 885 along the length of the ablation shaft / sleeve 881.

[0212] Although Fig.25AFour (4) multi-layer cryogen delivery tubes 888, four (4) multi-layer cryogen return tubes 889, and four (4) service tubes / lumens 891 are depicted, but embodiments of the present invention are not intended to be so limited and may include any number of multi-layer cryogen delivery tubes 888, multi-layer cryogen return tubes 889, and service tubes / lumens 891, depending on the desired ablation capabilities of the catheter or the conditions that the catheter will be used to treat. Fig.25A A specific configuration of multi-layer refrigerant delivery tubes 888, multi-layer refrigerant return tubes 889 and service tube / cavity 891 is depicted, particularly pairs of multi-layer refrigerant delivery tubes 888 and multi-layer refrigerant return tubes 889 positioned adjacent to each other and separated by a service tube / cavity 891, but embodiments of the present invention are not intended to be so limited and may include any number of different configurations for multi-layer refrigerant delivery tubes 888, multi-layer refrigerant return tubes 889 and service channels / tubes 891.

[0213] Air gap elimination

[0214] In some embodiments, an annular space 813 (see FIG. 814 ) is defined between the inner surface 823 of the outer sheath 821 and the outer surface 822 of the hollow tube / lumen 890. Fig.25A ) is filled with a thermally conductive fluid (not shown) to eliminate air gaps / bubbles between the thermal elements 888, 889 and the outer sheath 821. Air gaps between the outer sheath and the refrigerant delivery and return tubes / thermal elements 888, 889 are undesirable because such gaps reduce heat transfer from the thermal elements to the target tissue.

[0215] An example of a suitable heat-conducting liquid is water. The heat-conducting liquid can be passed through the working line (for example, respectively Fig.11 and Fig.16 The space 813 is flushed with hot water until all air is removed from the space 813.

[0216] Furthermore, although water is described as a suitable thermally conductive medium for irrigation space 813, as described herein, embodiments of the present invention include the use of other thermally conductive materials to eliminate air gaps and increase thermal conductivity within the ablation portion of the catheter.

[0217] refer to Fig.25B , shows a cross-section of another embodiment of the catheter 881. Specifically, Fig.25A The cross sections shown are different. Fig.25BThe space 813 is shown filled with a solid thermally conductive material or bushing 833, which includes a base material and a filler with high thermal conductivity. Exemplary base materials for the thermally conductive bushing 833 include, but are not limited to, thermoplastic elastomers (TPE) or thermoplastic polyurethanes (TPU) suitable for conducting thermal energy. Exemplary filling materials include, but are not limited to, aluminum, copper, silver, and gold.

[0218] In some embodiments, the filler may be a ceramic material with good thermal conductivity, and the ceramic material is preferably electrically insulating so as to isolate any electrodes included on the ablation portion of the catheter as discussed herein. Exemplary ceramic filler materials include, but are not limited to, BN (boron nitride), AlN (aluminum nitride), Si3N4 (silicon nitride), SiC (silicon carbide), Al2O3 (aluminum oxide), and ZnO (zinc oxide).

[0219] As will be readily appreciated by those skilled in the art, any material having high thermal conductivity may be used as the filling material.

[0220] The TPE or TPU (base material) is loaded with a thermally conductive agent or filler to increase the thermal conductivity of the base material. An example of a TPE is polyether block amide (PEBA), which is also known and manufactured by Arkema (France) under the trade name An example of TPU is manufactured by Lubrizol (Wickliffe, Ohio). One example of a conductive agent or filler is alumina.Preferably, the conductive filler or agent increases or significantly increases the thermal conductivity of the composite material, as further described below.

[0221] In a particular embodiment, the material is PEBA loaded with about 10%-70% by weight of aluminum oxide (Al2O3), and in a particularly preferred embodiment, the material is PEBA loaded with about 65-75% by weight of Al2O3.

[0222] The base material (eg, TPE or TPU) may be loaded with thermally conductive fillers by mixing the base material with the fillers into a pelletized material and then extruding the loaded material into a desired conduit suitable for lining with thermal elements 888, 889 as described herein.

[0223] In an embodiment, the base material is loaded such that the thermal conductivity (K) of the liner 833 is at least three to five times greater than the base material not modified with the thermally conductive filler, more preferably at least five times greater. In an embodiment, the thermal conductivity (K) of the liner 833 is at least 1 W / mK at 23°C, and is in the range of from 0.5 W / mK to 3 W / mK.

[0224] The thermally conductive bushing 833 can be incorporated into the conduit or otherwise assembled into the conduit in various ways. In some embodiments, the bushing 833 is heat-fused on the thermal energy element 888, 889 and the service tube 891. During the heat fusion step, the bushing melts and flows around the thermal element 888, 889 and the service tube 891 until the air gap between the thermal element 888, 889 and the service tube 891 is completely filled and eliminated. In some embodiments, the outer sheath is then applied to the thermal element and the bushing, leaving no gap. In some embodiments, when the conductive bushing 833 is heat-fused on the thermal energy element 888, 889, the outer sheath is not necessary. In these embodiments, the bushing acts as a sheath. Adding a sheath may only increase the stiffness of the device or conduit. In addition, if the sheath is not made of a conductive material, the sheath can act as a thermal barrier.

[0225] The presence of the thermally conductive bushing 833 surrounding the thermal elements 888, 889 has a number of additional benefits, including simplifying the medical procedure and saving time because the physician no longer needs to flush the catheter space 813 with fluid to eliminate air gaps.

[0226] In addition, the thermally conductive bushing 833 makes the ablation portion of the catheter resistant to kinking. Without the thermally conductive bushing 833 between the outer sheath 821 and the thermal elements 888, 889, the thermal elements are not supported unless the thermal elements contact the outer sheath 821 (which typically occurs at the apex of the thermal elements). On the other hand, when the space 813 is filled with the thermally conductive bushing 833 described herein, the presence and properties of the bushing mechanically supports the thermal elements 888, 889 and the service tube 891 and provides greater kink resistance.

[0227] refer to Fig.25C , shows a cross-section of another embodiment of the conduit 881. In particular, Fig.25B The cross sections shown are different. Fig.25C The catheter 881 in includes a thermally conductive bushing 843 disposed only on the outside / perimeter of the thermal elements 888, 889 and the service tube 892. Therefore, there is an air-filled space 853 between the working cavity 890 and the internal thermal elements 888, 889 and the service tube 892. This space acts as a thermal barrier or insulator because air has a low thermal conductivity. However, the insulating space 853 is not disadvantageous because it is undesirable to conduct thermal energy to the hollow tube 890. In addition, leaving the space 853 open / without the conductive bushing 833 allows the thermal elements 888, 889 to move more freely. Therefore, the thermal elements 888, 889 are not bonded / connected to the hollow tube / cavity 890. This greatly increases the flexibility of the ablation catheter and allows one to obtain smaller bending radii and more complex shapes.

[0228] In addition, the thermoplastic bushings described herein can be adapted to bond various components of the conduit together and withstand temperature changes during operation. By filling the bushing with certain low linear coefficient of thermal expansion (LCTE) agents such as quartz, the bushing can be adapted to have a relatively low LCTE. In an embodiment, PEBAX is filled with about 60% quartz by weight. The reinforced bushing can be in the form of a tube that can be used to thermally fuse / bond various components of the conduit together. Preferably, the linear thermal expansion coefficient is reduced to 0.5 / K or less. Examples of components to be joined include matching thermal elements, liquid pipes, such as a liquid main pipe to a liquid secondary pipe or branch pipe, and other cavities for conveying liquids that are susceptible to thermal expansion caused by temperature changes.

[0229] The low LCTE enhanced bonding described herein does not require the use of an epoxy adhesive. Therefore, the low LCTE enhanced bonding does not require an adhesive curing cycle, making the low LCTE enhanced bonding faster than epoxy adhesives. In practice, the type and configuration of the thermally conductive medium, bushing, or conduit can vary greatly from various liquids to thermally conductive solids and from partially filling the space 813 to completely filling the space.

[0230] Although already targeted Fig.24 25 depicts the conductive sleeve 833, but the conductive sleeve 833 can be used in any of the ablation catheter embodiments disclosed and described herein. In addition, it is readily understood that the conductive sleeve 833 embodiments described and disclosed herein are not limited to use with ablation catheters, but can be used in any application to increase the conductivity of an item / component.

[0231] As will be readily appreciated by those skilled in the art, the disclosed and described embodiments of the conductive sleeve 833 may be used in any application to increase thermal conductivity, whether to enhance cooling / freezing or warming / heating. Thus, the disclosed and described embodiments of the conductive sleeve 833 may be used with many different ablation techniques, including but not limited to cryoablation, radiofrequency, microwave, laser, and high frequency ultrasound (HIFU).

[0232] Fig.26 Shows Fig.25AFIG. 8 is an enlarged cross-sectional view of a multi-layer cryogen delivery tube 888 and a multi-layer cryogen return tube 889. A first tube or inner tube 893 is shown as being coaxially surrounded by a second tube or outer tube 894. The cavity 895 of the inner tube 893 is designed to receive a flow of cryogen. The inner tube 893 and the outer tube 894 are arranged so that a space or gap 896 is formed between the outer surface of the inner tube 893 and the inner surface of the outer tube 894. As described herein, the gap 896 can be filled with a thermally conductive medium 897. In some embodiments, the gap 896 has an annular shape. All multi-layer cryogen delivery tubes 888 and multi-layer cryogen return tubes 889 can have a similar tube-in-tube structure.

[0233] During use, if the refrigerant flowing through the cavity 895 leaks or the inner tube 893 ruptures, the leaked refrigerant is contained in the gap 896 between the inner tube 893 and the outer tube 894. Since any leaked fluid / refrigerant is contained in the catheter and prevented from entering the patient's body, this tube-in-tube structure adds an additional safety factor to the device. In some embodiments, a pressure sensor / device or pressure gauge can be combined to monitor the pressure of the thermal conductive medium 897 in the gap 896. Therefore, if the fluid / refrigerant breaks through the inner tube 893 and leaks into the gap 896, the pressure in the gap 896 will increase, and therefore, the pressure of the conductive medium 897 will also increase. If the pressure change exceeds a threshold limit, the system can be programmed to (a) stop ablation, thereby preventing potential harm to the patient and / or (b) notify the surgeon of the pressure change.

[0234] The inner tube 893 can be prepared and made of materials related to other flexible tubes for conveying refrigerants / cooling fluids described herein. The outer tube 894 can also be made of a flexible material to enable the flexible shaft portion 884 and the flexible distal ablation portion 885 of the ablation shaft / cannula 881 to be elastically deflected, thereby allowing these portions to change their shape to present the shape of the needle 882 disclosed herein. In some embodiments, the outer tube 894 is non-inflatable, non-expandable, and non-expandable, so that its size and shape are substantially unaffected by the presence of the thermally conductive medium 897 contained therein. Non-limiting exemplary materials for the outer tube 894 include polymers and metals or alloys. An example of the outer tube 894 material is polyimide.

[0235] The diameter of the flexible distal ablation portion 885 can vary. In some embodiments, the diameter of the flexible distal ablation portion 885 is in the range of about 1-3 mm, and is preferably about 2 mm.

[0236] Fig.27A and Fig.27B An embodiment of an ablation catheter 880 is depicted with a stylet 882 fully inserted into an ablation shaft / cannula 881 .

[0237] Fig.28A Shown along Fig.27A The line 28-28 in Fig.27A A cross-sectional view of the ablation catheter 880. Fig.28A As can be seen, the stylet 882 is inserted into the hollow tube / lumen 890 of the ablation shaft / cannula 881. As previously disclosed, the stylet 882 may be made of a shape memory alloy, such as nickel titanium (Nitinol).

[0238] Figure 28B-Figure 28C They are respectively Figure 25B-Figure 25C The cross-sectional view shown is the same as the cross-sectional view except Figure 28B-Figure 28C A stylet 882 is shown inserted into the hollow tube / lumen 890 of the ablation shaft 881 .

[0239] Fig.29 Depicted in FIG. 8 is a sample shape that can be pre-set into the distal portion 898 of the stylet 882. In some embodiments, the length of the distal portion 898 corresponds to at least a portion of the length of the flexible distal ablation portion 885 of the ablation shaft / cannula 881. Thus, when the stylet 882 is in position in the hollow tube / lumen 890 of the ablation shaft / cannula 881 and the flexible distal ablation portion 885 is located at the ablation site in the patient's body, the distal portion 898 of the stylet 882 transforms into its pre-set shape, such that the flexible distal ablation portion 885 transforms into the shape of the stylet 882. Fig.27B The corresponding shape depicted.

[0240] The shape of the distal portion 898 of the stylet 882 can depend on the type of procedure / treatment to be performed by the ablation catheter 880 and the anatomy of the patient in which the treatment is being performed. Thus, for example, if a procedure is performed with one stylet 882 having a particular shape / orientation, and the ablation is unsuccessful due to incomplete lesion formation, the surgeon can remove only the stylet 882 from the ablation shaft / cannula 881 while leaving the ablation shaft / cannula 881 in place within the patient. The surgeon can then (a) select a different stylet 882 having a distal portion 898 that is a different size and / or shape than the previously used stylet 882, (b) insert the new stylet 882 into the hollow tube / lumen 890 of the ablation shaft / cannula 881, and (c) continue the ablation procedure. The surgeon can do this as many times as necessary to achieve successful ablation, e.g., complete lesion formation.

[0241] In some embodiments, a portion 899 of the needle 882 may be provided with a predetermined articulation angle, which may help guide the flexible distal ablation portion 885 into contact with the target tissue for ablation. In some embodiments, the articulation portion 899 of the needle 882 corresponds to the flexible shaft portion 884 of the ablation shaft / cannula 881.

[0242] In some embodiments, the stylet 882 can be designed to have varying flexibility along its length. Fig.30 As depicted, in one embodiment, the guide needle 882 can be designed to have three (3) portions, identified as portions "A", "B", and "C" having different flexibility. For example, portion "A" can have a first flexibility, portion "B" can have a second flexibility, and portion "C" can have a third flexibility. In some embodiments, portion "B" has greater flexibility than portions "A" and "C" because portion "B" of the ablation shaft / cannula 881 and its associated portions may need to be articulated so that portion "A" of the ablation shaft / cannula 881 and its associated portions can be manipulated into contact with the target tissue to be ablated within the heart. Portions "A" and "C" of the ablation shaft / cannula 881 and their associated portions may need to be less flexible / more rigid or stiffer than portion "B" so that pressure / force can be applied and transmitted to the flexible distal ablation portion 885 of the ablation shaft / cannula 881 during delivery of the ablation shaft / cannula 881 so that the flexible distal ablation portion 885 can be manipulated into an appropriate position against the target tissue and maintained in an appropriate position.

[0243] In some embodiments, portions of the stylet 882 may be designed to have similar flexibility as corresponding portions of the ablation shaft / cannula 881. In some embodiments, the ablation shaft / cannula 881 may be designed to have uniform flexibility, however, the flexibility of a particular portion of the ablation shaft / cannula 881 may be adjusted or controlled based on the flexibility of corresponding portions of the stylet 882. Thus, the stylet 882 may be responsible for controlling the flexibility of the catheter 880.

[0244] The flexibility along the length of the via 882 can be altered or changed in a variety of ways. For example, in some embodiments, the properties of the shape memory material that makes up the via 882 can be changed. One property that can be changed is the transformation temperature of the shape memory alloy. Thus, a shape memory alloy having a certain flexibility at one temperature can have a different flexibility at the same temperature due to a change in the transformation temperature.

[0245] like Fig.31A and Fig.31B As depicted, in one embodiment, the flexibility along the length of the stylet 882 can be varied by changing the diameter of the stylet 882. Fig.31B yes Fig.31A CTV Fig.31BDetail of the invention is shown, showing that material may be removed from the stylet 882 such that portions of the stylet 882 have a diameter "d1" while other portions of the stylet 882 have a diameter "d2" that is less than the diameter "d1". Thus, portions of the stylet 882 that have diameters that alternate between "d1" and "d2" or that have an extended length "L2" of diameter "d2" are more flexible than portions of the stylet 882 that have a consistent diameter "d1". In some embodiments, flexibility may vary based on the length "L1" of the larger diameter portion "d1" and the length "L2" of the smaller diameter portion "d2", respectively. Thus, portions of the stylet 882 that have a length "L2" of the smaller diameter portion "d2" that is greater in length than the length "L1" of the larger diameter portion "d1" will be more flexible than portions of the stylet 882 that have a length "L2" of the smaller diameter portion "d2" that is shorter in length than the length "L1" of the larger diameter portion "d1". In other embodiments, any number of different diameter needle portions (i.e., "d1", "d2", "d3", "d4", etc. of any length) can be designed to impart the desired flexibility to the needle 882, and these different diameter needle portions can be arranged in any order and / or configuration to impart the desired flexibility to the needle 882.

[0246] In some embodiments, Figure 32A-32C As depicted, the flexibility of a portion of the stylet 882 can be varied by including a plurality of circumferential grooves 5000, a plurality of longitudinal grooves 5010, or a plurality of holes 5020. Fig.32A In the depicted embodiment, the flexibility of the through needle 882 can be varied based on the width "W1" of the circumferential groove 5000, the spacing "S1" between adjacent grooves 5000, and the spacing "L2" between adjacent groups 5030 of circumferential grooves 5000. Thus, (a) embodiments having circumferential grooves 5000 with a greater width "W1" than the width "W1" of the circumferential grooves 5000 in other embodiments, (b) embodiments having circumferential grooves 5000 with a spacing "S1" between adjacent grooves 5000 closer than the spacing "S1" between adjacent circumferential grooves 5000 in other embodiments, and (c) embodiments having groups 5030 of circumferential grooves 5000 with a shorter distance "L2" between adjacent groups 5030 of circumferential grooves 5000 than in other embodiments will be more flexible than in other embodiments. Various combinations of width "W1", spacing "S1", and distance "L2" can be designed to achieve the desired flexibility of different portions of the through needle 882.

[0247] exist Fig.32BIn the depicted embodiment, the flexibility of the stylet 882 can be varied based on the width "W2" of the longitudinal grooves 5010, the spacing "S1" between adjacent grooves 5010, the spacing "L2" between adjacent groups 5040 of longitudinal grooves 5010, and the length "L3" of the longitudinal grooves 5010. Thus, (a) embodiments having longitudinal grooves 5010 with a width "W2" greater than the width "W2" of the longitudinal grooves 5010 in other embodiments, (b) embodiments having longitudinal grooves 5010 with a length "L3" greater than the length "L3" of the longitudinal grooves 5010 in other embodiments, (c) embodiments having longitudinal grooves 5010 with a spacing "S1" between adjacent longitudinal grooves 5010 closer than the spacing "S1" between adjacent longitudinal grooves 5010 in other embodiments, and (d) embodiments having groups 5040 of longitudinal grooves 5010 with a distance "L2" between adjacent groups 5040 of longitudinal grooves 5010 shorter than in other embodiments will be more flexible than in other embodiments. Various combinations of width “ W2 ”, length “ L3 ”, spacing “ S1 ”, and distance “ L2 ” may be designed to achieve desired flexibility of different portions of the stylet 882 .

[0248] exist Fig.32C In the depicted embodiment, the flexibility of the through-pin 882 can be varied based on the diameter "D3" of the hole 5020, the spacing "S1" between adjacent holes 5020 in the X direction, the spacing "S2" between adjacent holes 5020 in the Y direction, and the spacing "L2" between adjacent groups 5050 of holes 5020. Thus, (a) embodiments having holes 5020 with a larger diameter "D3" than the diameter "D3" of holes 5020 in other embodiments, (b) embodiments having holes 5020 with a spacing "S1" between adjacent holes 5020 in the X direction that is closer than the spacing "S1" between adjacent holes 5020 in the X direction in other embodiments, (c) embodiments having holes 5020 with a spacing "S2" between adjacent holes 5020 in the Y direction that is closer than the spacing "S2" between adjacent holes 5020 in the Y direction in other embodiments, and (d) embodiments having groups 5050 of holes 5020 with a shorter distance "L2" between adjacent groups 5050 of holes 5020 than in other embodiments will be more flexible than in other embodiments. Various combinations of diameter "D3", spacing "S1", spacing "S2", and distance "L2" can be designed to achieve the desired flexibility of different portions of the pass pin 882.

[0249] In most embodiments, the degree of flexibility is related to the amount of stylus material removed or retained in the portion of stylus 882 where the change in flexibility is desired. The portion of stylus 882 where more material is removed will be more flexible than the portion of stylus 882 where less material is removed.

[0250] In the embodiment of the needle disclosed herein, a combination of variations can be used. For example, by combining a smaller diameter portion with a circumferential groove 5000 and / or a longitudinal groove 5010 and / or a hole 5020, the desired flexibility can be obtained.

[0251] The multiple flexibilities in the embodiments disclosed herein are due to the removal of material in portions of the stylet along its length. The removed material may be in the form of smaller diameter portions, circumferential grooves, longitudinal grooves and / or holes, and any other shapes apparent to one skilled in the art.

[0252] In some embodiments, the ablation catheter 880 can be packaged as a kit having a variety of pass needles 882 of various shapes and sizes, thereby giving the physician different options regarding the size and shape of the lesion to be produced during the ablation procedure. These kits can be treatment-specific. Therefore, only pass needles having shapes and sizes for specific surgeries are included in the kit. Therefore, the ablation catheter 880 of this embodiment allows for the design and construction of a single universal ablation shaft / cannula 881 that can be used for a variety of different ablation procedures based solely on providing a pass needle 882 specific to the procedure being performed. Constructing a single universal ablation shaft / cannula 881 is more cost-effective and provides higher productivity than having to construct multiple ablation catheters designed to have different shapes and different handle functions.

[0253] In some embodiments, the ablation shaft / cannula 881 can be used to perform ablation without the stylet 882 inserted therein.

[0254] As will be discussed in more detail below, in use, the ablation shaft / cannula 881 is delivered to a region of interest in the body via a delivery catheter, in some embodiments, for example, to the left atrium of the heart to treat atrial fibrillation, or to the right atrium to treat atrial flutter, or to the right and left ventricles to treat ventricular tachycardia. After the ablation shaft / cannula 881 is in place, the surgeon elects to use the stylet 881, depending on the ablation treatment being performed and the patient's anatomy. The surgeon then inserts the stylet 881 into the hollow tube / lumen 890 of the ablation shaft / cannula 881 via the catheter handle until the distal portion 898 of the stylet 882 is in place in the flexible distal ablation portion 885. Once in place, the shape memory properties of the distal portion 898 of the stylet 882 cause the distal portion 898 to transform into its preset shape, thereby causing the flexible distal ablation portion 885 to transform into a corresponding shape. The surgeon can then proceed with the ablation treatment.

[0255] application

[0256]

[00136] Embodiments of cryoablation devices (catheters, probes, etc.) described herein have a wide range of diagnostic and therapeutic applications, including, for example, endovascular-based cardiac ablation, and more specifically, endovascular-based cardiac ablation treatment of atrial fibrillation.

[0257] Fig.33 An example of a target ablation lesion in a pulmonary vein isolation (PVI) procedure for treating atrial fibrillation is shown.

[0258] The basic structure of the heart 1 Fig.33 , including right atrium 2, left atrium 3, right ventricle 4 and left ventricle 5. Blood vessels include aorta 6 (accessed via femoral artery), superior vena cava 6a (accessed via subclavian vein) and inferior vena cava 6b (accessed via femoral vein).

[0259] Exemplary target lesions for a PVI procedure include a lesion 8 that surrounds and isolates all of the left pulmonary veins (PV), and a lesion 9 that surrounds and isolates all of the right pulmonary veins (PV). As further described herein, the present invention may include the application or creation of additional lesions to increase the effectiveness of the treatment. In addition, it should be understood that although the following discussion focuses primarily on embodiments for performing PVI, the techniques and processes described herein for creating these lesions can be used to create other lesions around the heart and in other organs, such as described in Cox et al. International Patent Applications No. PCT / US2012 / 047484 and Cox et al. International Patent Applications No. PCT / US2012 / 047487, corresponding to International Publication Nos. WO2013 / 013098 and WO2013 / 013099, respectively, the contents of each of which are hereby incorporated by reference in their entirety.

[0260] Fig.34 A technique for reaching the left atrium with the distal treatment segment of the catheter is shown. The procedure can be performed under conscious sedation or, if desired, general anesthesia.

[0261] A peripheral vein (eg, femoral vein FV) is punctured with a needle. The puncture wound is enlarged using a dilator to a size sufficient to accommodate an introducer sheath, and an introducer sheath having at least one hemostatic valve is positioned within the enlarged puncture wound while maintaining relative hemostasis.

[0262] With the introducer sheath in place, the guide catheter 10 or sheath is introduced through the hemostatic valve of the introducer sheath and advanced along a peripheral vein to the target cardiac region (eg, the vena cava and into the right atrium 2). Fluoroscopic imaging may be used to guide the catheter to the selected site.

[0263] Once in the right atrium 2, the distal tip of the guide catheter is positioned against the fossa ovalis in the intra-atrial septal wall. The needle or trocar is then advanced distally through the guide catheter until it pierces the fossa ovalis. A separate dilator may also be advanced through the fossa ovalis using the needle to prepare an access port through the septum for placement of the guide catheter. Thereafter, the guide catheter replaces the needle through the septum and is placed in the left atrium through the fossa ovalis, thereby providing access for the device to pass through its own cavity and into the left atrium.

[0264] Placement of the above tools may be performed under the guidance of one or more of the following: fluoroscopy, intracardiac pressure, transesophageal echocardiography (TEE), and intracardiac echocardiography (ICE).

[0265] Figure 35-38 A method is shown for deploying a loop catheter in the left atrium and around the entrance of the pulmonary veins for treating various heart diseases, such as atrial fibrillation.

[0266] First reference Fig.35 , a cross-sectional view of the heart including the right atrium RA2, the left atrium LA3, the entrance of the left superior pulmonary vein LSPV, and the entrance of the left inferior pulmonary vein LIPV. A guide catheter 2100 is shown extending through the septum and into the left atrium.

[0267] Although not shown, a mapping catheter can be located at the entrance of the LSPV in the left atrium to monitor the heart's electrical signals. Mapping catheters can be placed in other locations, such as the coronary sinus (CS). Examples of mapping catheters include Bidirectional catheter and catheters, both manufactured by Biosense Webster Inc., Diamond Bar, CA 91765, USA. Another example of a mapping and cryotherapy system is described in US Patent Publication No. 2015 / 0018809 to Mihalik.

[0268] Optionally, an esophageal warming balloon may be placed in the esophagus to mitigate collateral damage caused by the formation of the lesion. The esophageal warming balloon prevents cold temperatures from reaching the lining of esophageal cells and may prevent the formation of, for example, an atrial-esophageal fistula. An example of a suitable esophageal warming balloon device that may be used is described in commonly assigned U.S. Patent Application No. 15 / 028,927, filed October 12, 2014 by Alexei Babkin et al., entitled "ENDOESOPHAGEAL BALLOON CATHETER, SYSTEM, AND RELATED METHOD," the contents of which are incorporated herein by reference in their entirety for all purposes.

[0269] Fig.36The distal segment of the cryoablation catheter 2116 is shown being advanced through the guide sheath 2100. The energy element 2118 is shown having a circular shape formed as disclosed and described herein and being advanced toward the endocardium. As described herein, the shape can be adjusted to continuously contact the tissue and form a continuous lesion (e.g., an elliptical or circular shape) Fig.33 Lesion 8) is shown, which encircles all left PV inlets.

[0270] In embodiments, the shape is modified by reducing the diameter of the ring, articulating the middle section of the shaft, and rotating or manipulating the distal section of the catheter. Collectively, the steps of deployment, diameter control, manipulation, and articulation can place the entire circumference of the ring in continuous contact with the endocardial tissue. When energy is applied to the distal treatment segment, for example by flowing a cryogen through the distal treatment segment, a continuous elongated annular lesion (frozen tissue) is formed, e.g. Fig.33 Lesion 8 is shown, encircling all of the left pulmonary vein inlets.

[0271] Fig.37 The formation of annular lesions around the entrance of the right superior pulmonary vein (RSPV) and the entrance of the right inferior pulmonary vein (RIPV) are shown, for example Fig.33 The injury shown is 9. Figure 35-36 The slightly linear (straight shot) positioning shown is opposite, Fig.37 The catheter neck region 2116 is shown deflected nearly 180 degrees to target the right pulmonary vein. The energy element portion 2118 is located around the RSPV and RIPV entrances.

[0272] Fig.37 The energy element 2118 is shown deployed in a circular shape and contacting the endocardium. As described herein, the shape can be adjusted to better contact the tissue, thereby forming an elongated annular continuous lesion that engulfs or surrounds the RSPV and RIPV portals.

[0273] A similar elongated, annular continuous lesion may be created to surround the entrance of the left superior pulmonary vein (LSPV) and the entrance of the left inferior pulmonary vein (LIPV).

[0274] Fig.38 The catheter 2116 is shown deflected to target the posterior wall of the left atrium. The energy element portion 2118 is manipulated to form a loop and is pushed toward the posterior wall, overlapping the previously formed right and left lesions.

[0275] Optionally and not shown, a guidewire may be advanced from the introducer sheath and used to guide the catheter treatment segment into position.

[0276] The shape and pattern of the lesions may vary. In the embodiments, reference Fig.39, shows a "box-shaped" lesion 900 surrounding multiple pulmonary vein entrances during a PVI procedure. The box-shaped lesion surrounds the pulmonary vein entrances on the left and right sides of the left atrium.

[0277] The box-shaped lesion 900 can be formed in a variety of ways. In some embodiments, the box-shaped lesion is formed by overlapping a combination of lesions, which may have similar or different shapes (e.g., oval, elliptical, circular, etc.) to form an overall larger continuous lesion, which may have a shape such as Fig.39 Box shape 900 is shown.

[0278] refer to Fig.40 The diagram shown in Fig.41 , describes a method 1000 for forming a box-shaped lesion in the left atrium that surrounds / encloses the entrances of all pulmonary veins (RSPV, RIPV, LSPV, and LIPV).

[0279] Step 1010 recites advancing the cryoablation catheter into the left atrium, which may be performed using, for example, an introducer sheath.

[0280] Step 1020 recites directing the treatment segment of the catheter (energy element portion 2118) to one side of the left atrium and into the sinuses of the superior and inferior pulmonary veins on that side of the atrium.

[0281] Step 1030 recites manipulating the treatment segment of the catheter (energy element portion 2118) to form a ring shape and adjust the size of the ring to achieve complete circumferential tissue contact with the tissue surrounding the superior and inferior venous inlets on that side of the atrium.

[0282] Step 1040 states verifying tissue contact. This step may be performed using, for example, electrodes mounted on the distal treatment segment, as disclosed and described in commonly assigned International Patent Application No. PCT / US16 / 51954, filed on September 15, 2016 by Alexei Babkin et al., entitled “TISSUE CONTACT VERIFICATION SYSTEM,” the entire contents of which are incorporated herein by reference for all purposes. An EP recording system may be used to display a tissue electrocardiogram (ECG).

[0283] Optionally, an esophageal balloon (EBB) (described above) is advanced into the esophagus near the heart. During ablation therapy, the EBB is inflated and a thermally conductive fluid is circulated in the balloon. As described herein, the EEB minimizes collateral damage to tissue near the ablation zone by heating the tissue during the ablation cycle.

[0284] Step 1050 states performing ablation by freezing tissue to create a first continuous lesion on a first side of the left atrium surrounding / around the entrance of the pulmonary veins, e.g., Fig.40 The left lesion 901 in FIG. The duration of tissue freezing may be up to 3 minutes or longer, typically in the range of about 1 to 3 minutes, preferably about 2 minutes. In an embodiment, the freezing step comprises a single application of uninterrupted ablation energy.

[0285] In some embodiments, the duration of energy application is in the range of about 10 seconds to 60 seconds, sometimes less than or equal to about 30 seconds.

[0286] The duration of the freeze cycle may vary. The physician or electrophysiologist may choose to terminate the freeze cycle as desired (e.g., before or after the expected period of time has elapsed). Examples of reasons for early termination include: a desire to reposition the catheter, a desire to improve catheter-tissue contact, or safety concerns.

[0287] Step 1060 states confirmation that ablation is complete. Electrical activity from electrodes on the distal treatment segment may be monitored. During the freezing process, an electrocardiogram (ECG) will show abnormal signals due to freezing of tissue and blood in contact with the freezing tip. However, after freezing is complete, the ECG should not show any signals or evidence of voltage potentials in the tissue due to tissue necrosis.

[0288] However, if after the freeze step, the ECG signal / signature reappears, indicating that there is still electrical activity in the tissue, this indicates that the ablation is not complete and PVI may not have been achieved. If PVI is not achieved, the above applicable steps can be repeated.

[0289] In some embodiments, another freeze can be initiated at the same location. Alternatively, the catheter can be repositioned or otherwise adjusted to better contact the target tissue. Then, an additional freeze can be performed.

[0290] Performing additional freezes may be beneficial, especially when the distance between the pulmonary veins is abnormally large. Isolating the pulmonary vein entrances with only one contiguous lesion is challenging when the distance between the pulmonary veins is abnormally large. In a subpopulation of patients with abnormally large hearts, the formation of additional lesions around the pulmonary vein entrances increases the likelihood of complete and durable PVI.

[0291] Additionally, in some cases, it may be desirable to reduce the ablation loop to accommodate a single vein. In an embodiment, the method includes performing a single vein isolation around the ostium of a single vein. The diameter of the catheter loop is reduced from a relatively large size used to isolate multiple veins to a suitable size for a single vein. In an embodiment, a single vein isolation is performed after a larger multiple vein isolation.

[0292] Step 1070 states that the applicable steps are repeated for the pulmonary vein on the other side of the left atrium. That is, for example, after the left sinus is isolated, the catheter loop will be navigated to the right sinus, and all relevant steps should be repeated to create a second right lesion (e.g., Fig.40 damage 902).

[0293] Step 1080 states that the posterior wall injury ( Fig.40 The above applicable steps are repeated for the lesion in 903. Once the LSPV and LIPV sinuses and the RSPV and RIPV sinuses are isolated, the annular treatment segment of the catheter is guided to the posterior wall of the left atrium.

[0294] Optionally, the EBB is inflated within the esophagus and activated prior to posterior wall ablation. For the posterior lesion, the other applicable steps for placing the left and right lesions are repeated. The posterior lesion 903 is located more centrally and at Fig.40 Overlapping left and right sinus lesions (901 and 902, respectively) are shown in FIG. Lesion 903 is also shown extending from the bottom to the top of the left atrium.

[0295] Although the method describes a particular order of creating left pulmonary vein, right pulmonary vein, and posterior wall lesions, embodiments of the present invention are not intended to be so limited unless specifically stated in the appended claims. The order in which the lesions are created may be different. For example, in embodiments, right or posterior lesions may be performed before left lesions.

[0296] from Fig.39 and Fig.40 It can be seen that multiple independent damages (901, 902, 903) together form a composite box-shaped continuous damage 900 ( Fig.39 ), which surrounds all pulmonary vein entrances on all sides (left, right, top and bottom) of the left atrium. In embodiments, the sum of the sub-lesions forms a shell in the shape of a box, square or rectangle. Performing ablation to form this composite, continuous lesion 900 effectively electrically isolates all pulmonary vein entrances in the left atrium.

[0297] In patients with atrial flutter in addition to paroxysmal atrial fibrillation and in patients with non-paroxysmal atrial fibrillation, in addition to forming the above reference Figure 39-41 In addition to the lesions discussed (901, 902, 903), it may be necessary to create additional lesions to isolate the mitral valve. Fig.42 As shown, there is electrical activity / current 950 flowing around the mitral valve 960. Therefore, in order to treat these patients, the flow of this electrical activity / current 950 must be interrupted and stopped / prevented. Fig.43A and 43B950. An example of a lesion that can be formed to interrupt the flow of current 950 is depicted in FIG. As can be seen in the figure, the mitral valve lesion 975 is connected to the box-shaped lesion 900 formed by the left pulmonary vein lesion 901, the right pulmonary vein lesion 902, and the posterior wall lesion 903.

[0298] like Fig.43A As shown, in one embodiment, mitral valve lesion 975 extends from near mitral valve 960 (mitral valve annulus) and intersects the flow path of current 950 and lesion 900. In this and other embodiments, it is important that mitral valve lesion 975 at least intersects the flow path of current 950 and lesion 900. Thus, mitral valve lesion 975 can be formed at various locations within the left atrium as long as it intersects the flow path of current 950 and connects to lesion 900. This type of lesion can be formed by changing the shape of the treatment segment of the catheter.

[0299] exist Fig.43B In the illustrated embodiment, the same annular treatment segment of the catheter used to create the left pulmonary vein lesion 901, the right pulmonary vein lesion 902, and the posterior wall lesion 903 can be used to create the mitral valve lesion 975. Fig.43B As shown, creating an annular or circular mitral valve lesion 975 causes the lesion 975 to intersect the flow path of the current 950 and lesion 900 at multiple points (A, B, C, D), thereby increasing the likelihood of a successful procedure.

[0300] If necessary, you can create a reference Fig.41 The above-mentioned box-shaped injury 900 is followed by a mitral valve injury 975. Fig.44 The method for performing the procedure is set forth in the flowchart shown, which includes forming the mitral valve lesion 975 after forming the box lesion 900 as step 1090. It will be apparent to one skilled in the art that the steps used in the procedure for forming the left pulmonary vein lesion 901, the right pulmonary vein lesion 902, the posterior wall lesion 903, and the mitral valve lesion 975 may be performed in any order as long as the procedure is followed to isolate all pulmonary vein entrances and interrupt the flow path of the current 950.

[0301] In another embodiment, in some patients with persistent atrial fibrillation, a linear lesion in the right atrium 2 may be necessary. Fig.45As depicted, the linear lesion 2500 is created to connect the entrance of the inferior vena cava (IVC) 6b and the annulus of the tricuspid valve (TV) 2510 and extend through the tricuspid isthmus (CTI) 2520. The CTI lesion is used to prevent / interrupt most potential re-entry circuits in the right atrium, such as right atrial flutter and / or other arrhythmias originating from the right atrium. This type of lesion is described in commonly assigned U.S. Patent Application No. 15 / 304,524, entitled "ENDOVASCULAR NEARCRITICAL FLUID BASED CRYOABLATION CATHETER HAVING PLURALITY OF PREFORMEDTREATMENT SHAPES," filed by Alexei Babkin et al. on October 15, 2016, the contents of which are incorporated herein by reference in their entirety for all purposes.

[0302] In some embodiments, for certain patients, in addition to forming the above reference Figure 39-41 The damage discussed (901, 902, 903) also needs to form the above reference Fig.45 Discussed CTI lesion 2500. It will be apparent to one skilled in the art that the steps used in the procedure for forming the left pulmonary vein lesion 901, the right pulmonary vein lesion 902, the posterior wall lesion 903, and the CTI lesion 2500 can be performed in any order as long as the procedure is followed, isolating all pulmonary vein entrances, and interrupting / blocking most potential re-entry circuits in the right atrium.

[0303] In some embodiments, for certain patients, in addition to forming the above reference Figure 39-41 The lesions discussed (901, 902, 903) and the above references Fig.43A , Fig.43B and Fig.44 In addition to the mitral valve injury discussed above, the above reference Fig.45 Discussed CTI lesion 2500. It will be apparent to one skilled in the art that the steps used in the procedure for forming the left pulmonary vein lesion 901, the right pulmonary vein lesion 902, the posterior wall lesion 903, the mitral valve lesion 975, and the CTI lesion 2500 may be performed in any order, provided that the procedure is followed, to isolate all pulmonary vein entrances, interrupt the flow path of the electrical current 950, and interrupt / block most potential re-entry circuits in the right atrium.

[0304] Numerous modifications and variations of the present invention are possible in light of the above teachings.It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

1. An ablation device for producing a lesion in a target tissue, the ablation device comprising: handle; An elongated shaft extending from the handle to a distal tip, the shaft comprising: Part I; an ablation portion, the ablation portion being away from the first portion; at least one ablative energy element, the at least one ablative energy element comprising at least one ablative energy delivery lumen and at least one ablative energy return lumen; a space surrounding each of the at least one ablation energy delivery lumen and the at least one ablation energy return lumen; and A solid, thermally conductive bushing is disposed in the space between the at least one ablation energy delivery lumen and the at least one ablation energy return lumen and is arranged to surround only a portion of each of the at least one ablation energy delivery lumen and the at least one ablation energy return lumen.

2. The ablation device according to claim 1, wherein: Each of the at least one ablation energy delivery lumen and the at least one ablation energy return lumen includes an inner tube having an outer tube surrounding the inner tube such that a gap is defined between the inner tube and the outer tube.

3. The ablation device according to claim 2, wherein: The gap is suitable for being filled with a thermally conductive medium. 4 . The ablation device according to claim 1 further comprises a plurality of ablation energy delivery lumens and a plurality of ablation energy return lumens.

5. The ablation device of claim 1, further comprising at least one electrode on an outer surface of the thermally conductive bushing. The ablation device according to claim 1 , further comprising at least one service lumen.

7. The ablation device according to claim 1, wherein: The ablative energy is derived from a cryogen flowing through the at least one ablative energy element.

8. The ablation device according to claim 7, wherein: The cryogen is near-critical nitrogen.

9. The ablation device according to claim 1 further includes a needle-access cavity and a needle-access cavity, wherein the needle-access cavity extends substantially along the length of the shaft from the handle to at least the ablation portion; in use, the needle-access cavity can be removably advanced into the needle-access cavity.

10. The ablation device according to claim 9, wherein: The stylet comprises a shape memory material, and wherein the stylet has a plurality of flexible portions along its length.

11. The ablation device according to claim 9, wherein: At least the distal portion of the stylet is pre-configured with a shape corresponding to the desired shape of the lesion to be formed.

12. The ablation device according to claim 1, wherein: The ablation device is used to treat a condition selected from the group consisting of atrial fibrillation, atrial flutter, and ventricular tachycardia.

13. The ablation device according to claim 1, wherein: The ablation portion also includes an outer sheath surrounding the thermally conductive bushing.

14. The ablation device according to claim 1, wherein: The thermally conductive bushing is a thermoplastic elastomer.

15. The ablation device according to claim 14, wherein: The thermoplastic elastomer is loaded with a thermally conductive material.

16. The ablation device according to claim 15, wherein: The thermoplastic elastomer is a polyether block amide loaded with alumina.

17. The ablation device according to claim 15, wherein: The thermoplastic elastomer is a polyether block amide loaded with alumina in an amount ranging from 10 to 70% by weight.

18. The ablation device according to claim 15, wherein: The thermoplastic elastomer is a polyether block amide loaded with boron nitride.

19. The ablation device according to claim 15, wherein: The thermoplastic elastomer is a polyether block amide loaded with boron nitride in the range of 10 to 70% by weight.

20. The ablation device according to claim 1, wherein: The thermally conductive sleeve surrounds the at least one ablation energy element by flow melting.

21. The ablation device according to claim 1, wherein: The ablation energy in the at least one ablation energy element reduces the temperature of the target tissue sufficient to cause ablation.

22. The ablation device according to claim 1, wherein: The ablation energy in the at least one ablation energy element increases the temperature of the target tissue sufficient to cause ablation.

23. An ablation system for creating a lesion in a target tissue, the ablation system comprising: A catheter comprising a handle, a distal tip, and an elongated shaft extending from the handle to the distal tip, the shaft comprising: Part I; an ablation portion, the ablation portion being away from the first portion; at least one ablative energy element; and a solid first thermally conductive medium, said first thermally conductive medium only partially surrounding said at least one ablation energy element; and An energy generator is coupled to the catheter to deliver and control ablation energy from the at least one ablation energy element to the target tissue.

24. The ablation system of claim 23, wherein: The at least one ablation energy element includes at least one ablation energy delivery lumen and at least one ablation energy return lumen.

25. The ablation system of claim 24, wherein: Each of the at least one ablation energy delivery lumen and the at least one ablation energy return lumen includes an inner tube having an outer tube surrounding the inner tube such that a gap is defined between the inner tube and the outer tube.

26. The ablation system of claim 25, wherein: The gap is suitable for being filled with a second heat conducting medium.

27. The ablation system of claim 24, further comprising a plurality of ablation energy delivery lumens and a plurality of ablation energy return lumens.

28. The ablation system of claim 23, wherein: The ablation energy is provided by a cryogen, and the flow of the cryogen to the ablation energy element is controlled by a controller.

29. The ablation system of claim 23, wherein: The first heat-conducting medium is a thermoplastic elastomer.

30. The ablation system of claim 29, wherein: The thermoplastic elastomer is loaded with a thermally conductive material.

31. The ablation system of claim 29, wherein: The thermoplastic elastomer is a polyether block amide loaded with alumina.

32. The ablation system of claim 31, wherein: The polyether block amide is loaded with alumina in an amount ranging from 10 to 70% by weight.

33. The ablation system of claim 29, wherein: The thermoplastic elastomer is a polyether block amide loaded with boron nitride.

34. The ablation system of claim 33, wherein: The polyether block amide is loaded with boron nitride in the range of 10 to 70% by weight.

35. The ablation system of claim 23, wherein: The first heat conductive medium surrounds the at least one ablation energy element by flowing and melting.

36. The ablation system of claim 23, wherein: The at least one ablation energy element reduces the temperature of the target tissue to cause ablation.

37. The ablation system of claim 23, wherein: The at least one ablation energy element increases the temperature of the target tissue to cause ablation.

38. The ablation system of claim 23, wherein: The catheter is used to treat a condition selected from the group consisting of atrial fibrillation, atrial flutter and ventricular tachycardia.

39. The ablation system according to any one of claims 23-38, wherein: The ablative portion further includes an outer sheath surrounding the first thermally conductive medium.

40. An ablation catheter for creating a lesion in a target tissue, the ablation catheter comprising: an elongated shaft extending from a handle of the ablation catheter to a distal tip, the shaft including an ablation portion distal to a first portion of the shaft; at least one ablative energy element; and A solid, thermally conductive sleeve only partially surrounds each of the at least one ablation energy element.

41. The ablation catheter according to claim 40, wherein: The ablation energy element is elongated and linear.

42. The ablation catheter according to claim 40, wherein: The ablation energy element includes a plurality of ablation energy elements.

43. The ablation catheter according to claim 42, wherein: The plurality of ablation energy elements are arranged in a circumferential pattern around the elongated hollow cavity.

44. The ablation catheter of Claim 43, further comprising a thermal barrier between the elongated hollow lumen and the plurality of ablation energy elements.

45. The ablation catheter of claim 40, wherein: The thermally conductive bushing is a thermoplastic filled with a thermally conductive agent.

46. ​​The ablation catheter of claim 42, wherein: The plurality of ablation energy elements includes a plurality of tubular elements adapted to deliver cryogen to and from the distal tip.

47. The ablation catheter according to any one of claims 40 to 46, wherein: The ablation catheter also includes an outer sheath surrounding the thermally conductive sleeve.

Images