Single-pass large-bore transseptal crossing

Abstract

The transseptal crossing system can include a sheath and an elongate tubular body. The tubular body can include an electrically conductive sidewall defining a central lumen and a distal end section. The central lumen can be configured to receive a guidewire and allow at least a portion of the guidewire to extend through a distal opening in the electrically conductive sidewall. The distal end section can include a distal end surface in electrical communication with the electrically conductive sidewall. The distal end surface includes a first section disposed generally orthogonally relative to a longitudinal axis of the elongate tubular body and a second section disposed at a non-orthogonal angle relative to the longitudinal axis of the elongate tubular body. At least one of the first section or the second section can be configured to deliver energy to a target tissue.

Description

[Background technology]

[0001] Introduction Transseptal access is used to access the left atrium across the septum from the right atrium for any of a variety of EP or structural heart procedures. For example, the left atrium is routinely accessed to assess hemodynamics and / or perform mitral valvuloplasty or to accommodate transvascular atrial fibrillation (AF) ablation procedures.

[0002] Crossing the septum typically requires locating and puncturing the fossa ovalis to access the left atrium, which can be accomplished using fluoroscopy and ultrasound, and in some cases echocardiography.

[0003] Mechanical puncture through the tissue of the fossa ovalis can be accomplished using a piercing device such as a standard Brockenbrough needle, as understood in the art, or a transseptal needle with a radiofrequency-energized tip, such as those manufactured by Baylis Medical Company, Inc.

[0004] The aforementioned devices and techniques have proven useful in a variety of EP and structural heart procedures where procedural access sheaths are often about 3.7 mm (about 11 French) or smaller. However, an increasing number of procedures, such as implantation of left atrial appendage closure devices and various mitral valve replacements or repairs, require "large bore" access, which is not possible using solely the techniques described above.

[0005] Instead, conventional transseptal punctures are performed using small-bore sheaths, typically in the range of 2.7 mm to 3.7 mm (8 French to 11 French), and then, in the case of the MitraClip Steerable Guide Catheter, these sheaths are exchanged over a rigid guidewire for larger-bore sheaths with outer dimensions as large as 8.0 mm (24 French). Dilators for transseptal sheaths typically accommodate a 0.032 wire, but Baylis introduced a small-bore transseptal sheath with a dilator that accommodates a 0.035 wire. Regardless of the transseptal sheath, the operator must utilize several additional instruments, including a small-bore transseptal sheath and dilator, and often a 0.025 "stiff" pigtail wire (Baylis, Toray) to use as a rail for advancing the small-bore transseptal sheath and dilator before switching to a 0.035 guidewire (Amplatz extra-stiff or Safari) to safely drive the large-bore sheath into the LA. The entire small-bore sheath must be driven into the LA and then switched to the appropriately stiff 0.035 guidewire to advance the large-bore sheath.

[0006] Thus, there remains a need for a transseptal crossing system based on 0.89 mm (0.035 inch) guidewire access that allows for single-pass crossing of larger sheaths, such as Boston Scientific's Watchman® guide sheath, Medtronic's Flexcath®, and others known in the art or yet to be disclosed. Summary of the Invention

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features, nor is it intended to limit the scope of the claims included herein.

[0008] Generally, the present disclosure provides a single-pass transseptal crossing device for enabling large-bore access in a single pass. The system includes an insulated cannula having a conductive tip positionable through a dilator in a large-bore sheath. The cannula tip is exposed distal to the tip of the dilator. The insulated cannula can serve as a conduit for an RF energy wire. The cannula can be energized to deliver RF energy directly to tissue and / or through a separate conductive wire or obturator. The insulated wire or obturator can be energized independently in this manner or passively energized via the energized cannula. The cannula has an outer diameter of 1.27 mm (0.050 inch) and an inner diameter of approximately 0.038 inch, allowing for the delivery of a 0.89 mm (0.035 inch) wire, which together (the stiff 0.89 mm (0.035 inch) wire and the 1.27 mm (0.050 inch) cannula) create a sturdy rail for advancing large bore dilators and sheaths in a single pass. The tip of the cannula can be non-orthogonal to deliver high density current to the angled edge of the cannula for improved cutting. The system allows for irrigation with hypotonic saline or D5W to preferentially drive current through the myocardium.

[0009] Thus, according to embodiments, a single-pass, large-diameter transseptal crossing catheter, such as for accessing the left atrium of the heart, is provided. The catheter includes an elongated, flexible tubular body having a proximal end, a distal end, and an electrically conductive sidewall defining a central lumen. An insulating layer surrounds the sidewall, leaving a first distal electrode tip exposed. An inner conductive wire having a second distal electrode tip is axially extendable and movably through the central lumen. A tubular insulating layer is disposed between the wire and the electrically conductive sidewall.

[0010] The first distal electrode tip may comprise an annular conductive surface at the distal end of the tubular body. The second distal electrode tip may be concentrically extendable through the annular conductive surface. The first distal electrode tip may comprise at least one distal protrusion, or at least two or three protrusions, and in one implementation comprises non-orthogonal distal edges.

[0011] The second distal electrode may have a smooth hemispherical surface or may be provided with a sharp distally facing protrusion. The catheter may additionally include an annular lumen between the tubular body and the wire, extending from the proximal hub to an exit port at the distal end.

[0012] According to a further embodiment, an introducer sheath for enabling single-pass, large-diameter transseptal crossing is provided. The introducer sheath comprises an elongate, flexible tubular body having a proximal end, a distal end, and an electrically conductive sidewall defining a central lumen. A tubular insulating layer may surround the sidewall, leaving an annular conductive surface exposed at the distal end. A proximal hub may be provided on the tubular body and have at least one access port in communication with the central lumen. A connector may be in electrical communication with the conductive sidewall and carried by the proximal end. The distal conductive surface may comprise at least one distal protrusion, or at least two or three protrusions, and in one implementation, comprises a non-orthogonal distal edge.

[0013] Also provided is a method of accessing the left atrium with a single-pass, large-bore catheter, the method including providing a single-pass, large-bore transseptal crossing catheter, positioning a distal end in contact with the fossa ovalis, and energizing the distal end to permit passage of the distal end into the left atrium.

[0014] The energizing step may include energizing a first distal electrode tip on the conductive tubular cannula and / or energizing a second distal electrode tip on the RF core wire. The first and second distal electrode tips may be energized in a bipolar mode.

[0015] The method may include accessing the left atrium, energizing the second distal electrode tip, advancing a wire through the fossa ovalis, then energizing the first distal electrode tip, and advancing a cannula into the left atrium.

[0016] A large bore access sheath can then be advanced over the transseptal crossing catheter into the left atrium, and the transseptal crossing catheter can then be removed, leaving the large bore access sheath extending into the left atrium.

[0017] An index procedure catheter can be advanced through the large-bore access sheath into the left atrium. The index procedure catheter can be configured to deliver a left atrial appendage implant, such as a closure device, or to accomplish mitral valve repair or replacement.

[0018] The incorporated drawings, which are incorporated in and constitute a part of this specification, demonstrate aspects of the disclosure and together with the description explain and illustrate the principles of the disclosure. [Brief explanation of the drawings]

[0019] [Figure 1] 1 illustrates a schematic representation of a transseptal crossing system. [Figure 2] FIG. 1 is a side elevation view of an RF needle. [Figure 2A]FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 2B] FIG. 3 is a detailed view of the distal tip of the needle of FIG. 2. [Figure 3] FIG. 3 is a cross-sectional view through the needle of FIG. 2. [Figure 4A] FIG. 12 is a detailed view of a distal energy delivery tip of one implementation. [Figure 4B] FIG. 12 is a detailed view of a distal energy delivery tip of one implementation. [Figure 4C] FIG. 12 is a detailed view of a distal energy delivery tip of one implementation. [Figure 5A] FIG. 10 is a detailed view of a distal energy delivery tip of another implementation. [Figure 5B] FIG. 10 is a detailed view of a distal energy delivery tip of another implementation. [Figure 5C] FIG. 10 is a detailed view of a distal energy delivery tip of another implementation. [Figure 6] 1 is a schematic cross-sectional view of a portion of a human heart with a transseptal crossing system positioned in the right atrium. [Figure 7] FIG. 7 is a view similar to FIG. 6 showing placement of the distal tip of the transseptal crossing system in the fossa ovalis. [Figure 8] The guidewire and cannula are shown penetrated into the fossa ovalis. [Figure 9] The large diameter sheath and dilator are shown penetrating the fossa ovalis. [Figure 10] The large bore sheath is shown in place across the septum with the dilator and other system components removed to provide access to the left atrium. [Figure 11] 1 shows an embodiment of a distal energy delivery tip. [Figure 12] 1 shows an embodiment of a distal energy delivery tip. [Figure 13] 1 shows an embodiment of a distal energy delivery tip. [Figure 14] 1 shows an embodiment of a distal energy delivery tip. [Figure 15] 1 shows an embodiment of a distal energy delivery tip. DETAILED DESCRIPTION OF THE INVENTION

[0020] In the following detailed description, reference is made to the accompanying drawings, in which identical functional elements are designated with like numerals. The aforementioned accompanying drawings illustrate, by way of example, and not by way of limitation, specific aspects and implementations consistent with the principles of the present disclosure. These implementations are described in sufficient detail to enable those skilled in the art to practice the disclosure, it being understood that other implementations may be utilized, and that structural changes and / or substitutions of various elements may be made without departing from the scope and spirit of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense.

[0021] It should be noted that the description herein is not intended to be an extensive overview, and thus concepts may be simplified for clarity and conciseness. All documents mentioned in this application are incorporated herein by reference in their entirety. Any process described in this application may be performed in any order, and any of the steps in the process may be omitted. A process may also be combined with other processes or steps of other processes.

[0022] 1 illustrates an embodiment of a tissue penetration device 102 in a transseptal crossing system 100. Device 102 comprises an elongate tubular body 104 having a distal region 106 and a proximal region 108. Distal region 106 is adapted to be inserted into and along a lumen of a patient's body, such as the patient's vasculature, and can be maneuvered through that lumen to a desired location adjacent to the tissue or other material to be pierced.

[0023] In some embodiments, the tubular body 104 can have at least one lumen extending from the proximal region 108 to the distal region 106, such as lumen 208 shown in FIG. 2A. The tubular body 104 can be constructed from a biocompatible polymeric material jacket, typically with a metal core that provides columnar strength to the device 102. The tubular body 104 can be sufficiently rigid to allow the dilator 84 and large-diameter guide sheath 12 (see FIG. 6) to be easily advanced over the device 102 and through the fenestration. Examples of suitable materials for the tubular portion of the tubular body 104 are stainless steel, nitinol, polyetheretherketone (PEEK), nylon, and polyimide. In the illustrated embodiment, the outer diameter along the tubular portion of the tubular body 104 can taper toward the distal region 106. In an alternative embodiment, the outer diameter along the tubular body 104 remains substantially constant from the proximal region 108 to the distal region 106.

[0024] The distal region 106 comprises a softer polymeric material with an optional embedded braid or coil so that it is flexible and atraumatic when advanced through the vasculature. In some embodiments, the material is also moldable (e.g., nitinol or stainless steel with a polymer jacket), so that its shape can be changed during manufacturing, typically by exposure to heat while set in a desired shape. In alternative embodiments, the shape of the distal region is changeable by the operator during use. An example of a suitable plastic is PEBAX (a registered trademark of Atofina Chemicals, Inc.). In this embodiment, the distal region 106 includes a curved portion 115.

[0025] The distal region 106 may have a preset curve that curls away from the overall axis of the sheath when advanced out of the guide sheath, helping to ensure that the energy delivery tip 112 is not in a position to inadvertently damage an undesired area within the patient's heart after transseptal puncture. The curve may be about 4 cm (about 1.57 inches) to about 6 cm (about 2.36 inches) long, and the curve may traverse about 225 to about 315 degrees of the circumference of a circle. For example, the curve may be about 5 cm long and traverse about 270 degrees of the circumference of a circle. Such an embodiment may be useful in avoiding undesired damage to intracardiac structures.

[0026] In some embodiments, the curved portion 115 begins about 0.5 cm to about 1.5 cm proximal to the energy delivery tip 112, leaving about 1 cm (about 0.39 inches) of straight section in the distal region 106 of the device 102. This ensures that this initial portion of the device 102 exits the dilator 84 (see FIG. 6) without bending, allowing an operator to easily position the device 102 against the septum, for example, as described further below. This feature further ensures that the distal region 106 of the device 102 does not begin to curve within the atrial septum.

[0027] The distal region 106 may have a smaller outer diameter than the remainder of the tubular body 104 so that expansion of the perforation is limited while the distal region 106 is advanced through the perforation. Limiting expansion is intended to ensure that the perforation does not cause hemodynamic instability after the device 102 is removed. In some embodiments, the outer diameter of the distal region 106 may be about 0.8 mm to about 1.0 mm or less. For example, the outer diameter of the distal region 106 may be about 0.9 mm (about 0.035 inches), which corresponds to the distal outer diameter of transseptal needles traditionally used to create perforations in the atrial septum. Similarly, in some embodiments, the outer diameter of the tubular body 104 may be about 1.0 mm (about 0.040 inches) to about 1.5 mm (about 0.060 inches). For example, the outer diameter of the tubular body 104 may be about 1.27 mm (about 0.050 inches), which also corresponds to the size of a transseptal needle.

[0028] The distal region 106 terminates in a functional tip region 110, which includes an energy delivery component and, optionally, an ECG measurement device. The functional tip region 110 includes at least one energy delivery tip 112 made of a conductive and optionally radiopaque material, such as stainless steel, tungsten, platinum, or another metal. One or more radiopaque markings may be attached to the tubular body 104 to highlight the location of the transition from the distal region 106 to the remainder of the tubular body 104 or other important landmarks on the device 102. Alternatively, the entire distal region 106 of the device 102 may be radiopaque. This can be achieved by filling the polymer material used to construct the distal region 106, such as PEBAX®, with a radiopaque filler. One example of a suitable radiopaque filler is bismuth. Distal region 106 may include at least one opening, such as exit port 109, which is in fluid communication with main lumen 200 (FIG. 2A), as further described below.

[0029] In the embodiment shown in FIG. 1 , the proximal region 108 includes a hub 114 to which a catheter connector cable 116 and a connector 118 are attached. A tube 117 and an adapter 119 may also be attached to the hub 114. The proximal region 108 may also include one or more depth markings 113 to indicate distance from the functional tip region 110 or other significant landmarks on the device 102. The hub 114 includes a bending direction or orientation indicator 111 on the same side of the device 102 as the curved portion 115 to indicate the direction of the curved portion 115. The orientation indicator 111 may include ink, etching, or other material to enhance visualization or tactile feel. One or more bending direction indicators may be used, and they may be of any suitable shape and size, and their locations may vary around the proximal region 108.

[0030] As shown in FIG. 1 , adapter 119 is configured to releasably couple device 102 to external pressure transducer 121 via external tubing 123. External pressure transducer 121 is coupled to monitoring system 125, which converts pressure signals from external pressure transducer 121 and displays pressure as a function of time. Catheter connector cable 116 may connect to an optional electrocardiogram (ECG) interface unit via connector 118. An optional ECG connector cable connects the ECG interface unit to an ECG recorder, which displays and captures ECG signals as a function of time. A generator connector cable may connect the ECG interface unit to an energy source, such as a generator (not shown). In this embodiment, the ECG interface unit may function as a splitter, allowing electrosurgical tissue perforation device 102 to be connected to both an ECG recorder and a generator simultaneously. The ECG signal can be continuously monitored and recorded, and filtering circuitry within the ECG interface unit can allow energy, e.g., RF energy, to be delivered from the generator 128 through the electrosurgical device 102 without impairing the ECG recorder.

[0031] In another embodiment (not shown) of the device 102, there may be a deflection control mechanism associated with the distal region 106 of the device 102 and an actuation mechanism for actuating the control mechanism associated with the proximal region 108 of the device 102. One or more pull wires may extend from the proximal control to the distal region 106 to actively deflect the distal region 106, as understood in the art. The control mechanism may be used to steer or otherwise actuate at least a portion of the distal region 106.

[0032] The generator 128 may be a radiofrequency (RF) electrical generator designed to operate in a high impedance range. Due to the small size of the energy delivery tip 112, the impedance encountered during RF energy application is very high. Typical electrosurgical generators are not typically designed to deliver energy within these impedance ranges, and therefore, only specific RF generators can be used with this device. In one embodiment, energy is delivered as a continuous wave at a frequency of approximately 400 kHz to approximately 550 kHz, e.g., approximately 460 kHz, a voltage of 100 to 200 V RMS, and a duration of up to 99 seconds. A grounding pad 130 is coupled to the generator 128 for attachment to the patient to provide a return path for RF energy when the generator 128 is operated in monopolar mode.

[0033] Other embodiments may use pulsed or discontinuous RF energy. Some embodiments of pulsed RF energy have RF energy at about 60 watts or less, a voltage of about 200 Vrms to about 400 Vrms, and a duty cycle of about 5% to about 50% at a frequency slightly above about 0 Hz to about 10 Hz. More specific embodiments include RF energy at about 60 watts or less, a voltage of about 240 Vrms to about 300 Vrms, and a duty cycle of 5% to 40% at 1 Hz, optionally with the pulsed RF energy delivered for up to 10 seconds. In one example, the generator can be configured to provide pulsed RF energy at about 50 watts or less, a voltage of about 270 Vrms, and a duty cycle of about 10% at 1 Hz. Alternatively, the pulsed RF energy may include RF energy at about 50 watts or less, a voltage of about 270 Vrms, and a duty cycle of about 30% at 1 Hz.

[0034] In still other embodiments of the device 102, different energy sources may be used, such as radiation (e.g., laser), ultrasound, heat, or electrical energy of other frequencies (e.g., microwave), with appropriate energy sources, coupling devices, and delivery devices, depending on the desired clinical performance.

[0035] Additional details of the tissue penetrating device 102 are described in relation to FIG. 2. Referring to FIGS. 2 and 2A, the tubular body 104 includes a cannula 206, such as a 0.050 inch (1.27 mm) cannula, with a central lumen 208 extending therethrough. The lumen 208 is sized to slidably receive a guidewire 210, such as a 0.035 inch (0.89 mm) guidewire. Of course, other sized guidewires may be utilized, including, but not limited to, a 0.032 inch (0.81 mm) guidewire. In certain implementations, it may be desirable to electrically insulate the guidewire 210 from the cannula 206. This may be achieved by providing a tubular insulating layer 212 disposed between the guidewire 210 and the cannula 206. In the illustrated embodiment, the insulating layer 212 comprises a coating or tubular sleeve that surrounds the guidewire 210. A further tubular insulating layer 214 may be provided on the outside of the cannula 206 to electrically insulate the cannula 206 from the patient. The tubular insulating layer 214 may include a coating or a tubular sleeve that surrounds the cannula 206.

[0036] Coatings may be included on any surface of any of the embodiments described herein. Coatings may affect one or more properties of the surface to which they are applied. For example, coatings may affect one or more of the following properties: smoothness, adhesion, flexibility, hardness, lubricity, and / or electrical resistance. In one embodiment, it is contemplated that the coatings on guidewire 210 and cannula 206 may have any of the same properties. However, in other embodiments, the coatings on guidewire 210 and cannula 206 may have different properties. For example, in one embodiment, insulating layer 214 on cannula 206 may include a coating that affects any of the following properties: electrical resistance, smoothness, and hardness. Furthermore, insulating layer 212 on guidewire 210 may include a coating that affects any of the following properties: smoothness, lubricity, and surface tension. Of course, in some embodiments, coatings may affect the properties of insulating layers 212, 214 to different degrees. For example, the coating may impart a degree of electrical resistance to the cannula 206 that is greater than the electrical resistance imparted to the guidewire 210 .

[0037] The coating may be applied in multiple layers. In some cases, the device may be selectively masked before coating and / or the coating may be removed from selective areas after coating. The coating may be removed by any suitable method, such as grinding, abrasive blasting, laser ablation, etc. In some embodiments, the coating may terminate at a portion of the cannula 206 proximal to the distal end 202.

[0038] Any of the guidewires described herein may include a coating to improve the lubricity of at least a portion of the guidewire. In some cases, the coating may not be for electrical resistance, such that the interaction between the guidewire and inner cannula is primarily mechanical with respect to clearance and friction.

[0039] 2B, there is shown a detailed view of the distal end 202 of the cannula 206 with a guidewire 210 extending therethrough. The guidewire 210 may include a pigtail or other curved distal end, as is understood in the art.

[0040] 3, tissue penetrating device 102 may additionally be provided with a Y-connector 220 having a proximal guidewire access port 222 and a flush port 224 in communication with distal region 106, such as via exit port 109 (FIG. 1) or central lumen 208 of cannula 206. Y-connector 220 may be provided with a distal first connector 226 configured to cooperate with a complementary second connector 228 at the proximal end of hub 114. First connector 226 and second connector 228 may be complementary components of a standard Luer connector, as understood in the art. Alternatively, hub 114 and Y-connector 220 may be formed as an integral unit.

[0041] 4A-4C illustrate the axial slidability of guidewire 210 within cannula 206. In FIG. 4C, the guidewire has been retracted proximally into central lumen 208, so that the leading surface of the system is annular charge transfer surface 207 comprising the distal end face of cannula 206. Insulating layer 214 on cannula 206 may extend distally to the edge of the end face of cannula 206, or proximally from the end face of cannula 206 by 2 mm, 1 mm, or less. This system therefore allows for RF energy delivery from either the guidewire alone, the cannula alone, or both, depending on the desired clinical performance.

[0042] A separately insulated cannula 206 and guidewire can be configured to deliver bipolar electricity to the distal tip. The cannula 206 can be used as a ground path, can replace a body pad or other electrode, and can provide desirable impedance characteristics depending on the desired clinical performance.

[0043] 5A-5C show a modified distal end face of cannula 206. At least one distal extension 230 is carried by cannula 206 to provide an area of ​​increased energy density on the forward charge transfer surface 207 carried by protrusions 221. At least two or four or more, such as ten protrusions 221 as shown in FIG. 5B, may be provided to form a scalloped surface with multiple circumferentially spaced distal charge transfer surfaces 207.

[0044] One method of delivering a large bore catheter in a single pass using a transseptal puncture system may be as follows. 1. Advance a guidewire (GW) into the superior vena cava (SVC) and deliver a large-bore catheter with a dilator (e.g., left atrial appendage closure device, mitral valve repair or replacement, intra-atrial adjustable annuloplasty device) into the SVC.

[0045] 2. Pull out the GW inside the dilator. 3. Withdraw the large-diameter sheath and dilator to the right atrium. 4. Maneuver the sheath and dilator to the appropriate position within the atrial septum, specifically tenting the septum with the dilator.

[0046] 5. Deliver the cannula and GW into position with the cannula extending distally beyond the dilator and the GW extending distally beyond the cannula in contact with the fossa ovalis.

[0047] 5a. If needed for placement purposes, withdraw the cannula proximal to the bend in the steerable sheath, then go to step 6. 6. The distal tip of the GW is activated with RF energy and the GW is passed through the septum into the left atrium (LA).

[0048] 7. Advance the cannula, dilator, and sheath distally through the septum into the LA. 8. If the cannula cannot pass through the septum into the LA, activate the distal tip of the cannula with RF energy and advance the cannula into the LA.

[0049] 9. Advance the dilator and large bore sheath over the access cannula and into the LA. 10. Withdraw the cannula and dilator and introduce the index procedure catheter through the large bore sheath.

[0050] As will be appreciated by those skilled in the art, the GW and cannula can alternatively be operated simultaneously in monopolar mode, with either the GW or the cannula being energized separately, or the GW and cannula can be operated in bipolar mode depending on the desired clinical performance.

[0051] Accordingly, referring to Figure 6, a schematic cross-sectional view of a portion of the heart 10 is shown. The right atrium 86 communicates with the inferior vena cava 88 and the superior vena cava 90. The right atrium 86 is separated from the left atrium 16 by the intra-atrial septum 18. The fossa ovalis 92 is located on the intra-atrial septum 18. As can be seen in Figure 6, the large-bore transseptal sheath 12 may have a dilator 84, both of which rest over the cannula 206 and the guidewire 210, all of which are positioned within the right atrium 86.

[0052] The sheath 12 and dilator 84 combination, with the transseptal cannula 206 and GW 210 extending distally, is then pulled proximally from the superior vena cava while the curved section of the sheath, alone or in combination with a preset curve in the distal region of the dilator 84 and / or cannula 206, "drags" the tip of the cannula-GW combination along the wall of the right atrium 86 and septum 18 with proximal traction until the tip emerges above the fossa ovalis 92, as shown in FIG. 7.

[0053] After the tip of the cannula-GW combination is positioned at the desired location relative to the fossa ovalis 92, RF energy is applied through the tip of the transseptal GW 210 to allow the GW 210 to pass through the septum and into the LA. As mentioned above, RF energy can also be delivered through the distal end of the cannula 206, if desired. See FIGS. 8 and 9.

[0054] One medical technique is to confirm the presence of the tip of the transseptal GW 210 within the left atrium 16. Confirmation of such location of the tip of the transseptal GW 210 can be achieved by monitoring the pressure sensed through the transseptal GW lumen, or the annular lumen defined between the GW 210 and the inner surface of the cannula 206 central lumen, to ensure that the measured pressure is within an expected range and has a waveform configuration typical of left atrial pressure. Alternatively, proper location within the left atrium 16 can be confirmed by analyzing the oxygen saturation level of blood drawn through the available lumen, i.e., by aspirating fully oxygenated blood. Finally, visualization by fluoroscopy alone or in combination with the use of dye can also serve to confirm the presence of the tip of the transseptal cannula 206 and GW 210 within the left atrium 16.

[0055] After positioning the tip of the transseptal cannula within the left atrium 16, the tip of the dilator 84 is advanced through the septum 18 and into the left atrium 16, as shown in FIGURE 9. Once the tapered tip of the dilator 84 is seen to have entered the left atrium 16, the transseptal cannula 206 may be withdrawn. The large-bore sheath 12 may then be advanced into the left atrium 16 by advancing the sheath 12 alone over the dilator 84, or by advancing the sheath 12 and dilator 84 in combination. The dilator 84 may then be withdrawn from the sheath 12 when the sheath 12 has been advanced into the left atrium, thus leaving the main lumen of the sheath 12 as an unobstructed path for advancing additional large-bore diagnostic or therapeutic instruments into the left atrium.

[0056] 11-15 are illustrations of various embodiments of modified distal end faces of cannulas, according to some embodiments. For example, FIG. 11 shows a cannula 306 with a distal end face 307 that is generally orthogonal to the longitudinal axis 302 of the cannula 306. As another example, FIG. 12 shows a cannula 406 with a distal end face 407 that is generally non-orthogonal to the longitudinal axis 402 of the cannula 406.

[0057] 13 shows a cannula 506 with a distal end face 507 having a first section 509 oriented at a first angle relative to the longitudinal axis 502 of the cannula 506 and a second section 510 oriented at a second, different angle relative to the longitudinal axis 502 of the cannula 506. Each or either of the first section 509 and second section 510 may lie in a plane such that each section of the end face is substantially linear when viewed from a side elevation. Alternatively, one or both of the beveled end faces may be non-linear, in which case the angles discussed herein are defined with respect to a transverse plane intersecting the two end points of the first or second section in question.

[0058] As yet another example, FIG. 14 illustrates a cannula 606 that is generally similar to cannula 506, but further has a blunt configuration. Cannula 606 can include a distal end face 607 having a first section 609 oriented at a first angle relative to a longitudinal axis 602 of cannula 606, a second section 610 oriented at a second, different angle relative to longitudinal axis 602 of cannula 606, and a third section 611 oriented at a third, different angle relative to longitudinal axis 602 of cannula 606. At least one of first section 609, second section 610, and third section 611 can lie in a plane such that each section of the end face is substantially linear when viewed from a side elevation. Alternatively, at least one of the end faces can be non-linear, in which case the angles discussed herein are defined with respect to a transverse plane intersecting the two end points of the first or second section of interest. The third section 611 may function as a radially outward facing angled deflection surface as described herein.

[0059] 15 shows a cannula 706 including a distal end face 707 having a first section 709 oriented at a first angle relative to the longitudinal axis of the cannula 706 and a second section 710 oriented at a second, different angle relative to the longitudinal axis of the cannula 706. The cannula 706 may include one or more rounded edges 712, 713 along an intersection between one or more sections of the cannula 706.

[0060] Unless otherwise noted, reference numbers in Figures 11-15 refer to components that are the same as or generally similar to corresponding components in the remaining figures discussed herein (e.g., a reference number may refer to a component having the same or similar last two digits as provided in the remaining figures). It will be understood that features described with reference to any one of cannulas 306, 406, 506, 606, 706 as shown in Figures 11-15, respectively, may be used with any of the other cannulas 306, 406, 506, 606, 706, or any other embodiment described and / or contemplated herein.

[0061] FIG. 11 illustrates an embodiment of a cannula 306 with a distal end surface 307 lying on a transverse plane lying generally perpendicular to the longitudinal axis 302 of the cannula 306 . 12 illustrates an embodiment of a cannula 406 comprising a substantially planar distal end surface 407 oriented at a non-orthogonal angle θ relative to the longitudinal axis 402 of the cannula 406. The non-orthogonal orientation may, in some cases, result in improved tissue penetration characteristics. The non-orthogonal or beveled orientation may advantageously minimize any undesired coring of tissue, thereby increasing the tissue thickness that can be easily penetrated by the cannula 406. For example, a beveled tip may facilitate penetration of tissue at least equal to the longitudinal length L1 of the angled distal end surface 407. The angled distal end surface 407 may advantageously penetrate tissue using mechanical and / or electrical methods.

[0062] FIG. 13 illustrates an embodiment of a cannula 506 comprising a distal end face 507 having a first section 509 disposed generally orthogonally relative to the longitudinal axis 502 of the cannula 506 and a second section 510 disposed at a non-orthogonal angle θ relative to the longitudinal axis 502 of the cannula 506. The combination of the first section 509 and second section 510 can, in some cases, improve the ability of the cannula 506 to create a tissue penetration at the leading first end face and facilitate tissue penetration with the angled second section 510. This multi-function tip allows for penetration by the first penetrating section 509, followed by expansion of the penetration upon distal advancement of the angled second section 510 through the penetration caused by the penetrating section 509. This configuration can minimize the risk of coring by forming a small tissue flap, resulting in an expandable tissue opening for receiving a device through the tissue flap.

[0063] The first section 509, in some embodiments, can include an arcuate end face extending between a first inflection point and a second inflection point. The arc length of the arcuate end face can generally be less than about 180 degrees and greater than about 45 degrees.

[0064] The length L2 (measured perpendicular to the longitudinal direction) of the first section 509 can be optimized depending on the use of the cannula 506. The surface area of ​​the first section 509, related to the length L2, affects the amount of force applied to the target tissue during treatment. The force is applied through manipulation of the handle of the system, which is operated by the user. The force applied to the target tissue by the first section 509 contributes to treatment by applying a mechanical component to the solution of coring. For example, when the appropriate force is applied, fissures or crevices are formed in the target tissue, thereby substantially reducing or preventing coring. The length L2 can be optimized taking these benefits into account.

[0065] As length L2 increases, length L1 may decrease depending on any adjustments to angle θ. Length L2 may be about 5% to about 75% of the diameter of distal end face 507 and / or the distal section of cannula 506. In some cases, length L2 may be about 10% to 50%, or more specifically, about 25% to about 30% of the diameter of distal end face 507 and / or the distal section of cannula 506. In one embodiment, length L1 may be about 20% to about 50% of the diameter of distal end face 507 and / or the distal section of cannula 506. In some embodiments, length L1 may be about 25% to about 30% of the diameter of distal end face 507 and / or the distal section of cannula 506.

[0066] Length L1 may be about 1 mm to about 2.5 mm. For example, length L1 may be about 1.5 mm to about 2 mm, or in some cases, about 1.75 mm. It is contemplated that if length L1 is too large, angled second section 510 (which, in some embodiments, may not include a coating) may remain open to the blood pool and, in some cases, may provide inconsistent puncture ability. Furthermore, if length L1 is too short, angled second section 510 may not provide the additional benefits described herein.

[0067] Length L2 may be between about 0.25 mm and about 0.75 mm. For example, length L2 may be between about 0.4 mm and about 0.6 mm, or in some cases, about 0.5 mm. It is contemplated that if length L2 is too short relative to length L1, first section 509 may be too sharp, which may reduce the effectiveness of first section 509 during use.

[0068] In some configurations, angle θ may be varied to provide a desired length L2 to maintain the non-coring tissue-penetrating characteristics of first section 509, while also providing a desired length L1 to achieve the tissue-distending characteristics of second section 510. For example, length L1 may be determined based on the target tissue thickness such that length L1 is formed to be equal to or greater than the target tissue thickness. For example, as angle θ approaches 0°, length L1 increases, thereby increasing the thickness of tissue that cannula 506 can penetrate while simultaneously reducing the risk of coring.

[0069] In one embodiment, angle θ can be between about 10° and about 70°. In some cases, angle θ can be between about 15° and about 50°, or more specifically, between about 20° and about 30°. In other embodiments, angle θ can be between about 15° and about 35°. For example, angle θ can be between about 20° and about 30°, or in some cases, about 25° or about 26°. In some embodiments, angle θ can be between about 40° and about 50°.

[0070] 14 illustrates an embodiment of a cannula 606 with a blunt configuration, which may be in the form of a radially outward-facing angled deflection surface, e.g., third section 611. The deflection surface, e.g., third section 611, may in some cases be a radiused curve or linear surface that slopes radially inward in the distal direction. The deflection surface, e.g., third section 611, may advantageously allow the needle to advance distally through the dilator while minimizing the risk of breaking off particles from the dilator's inner diameter with the relatively sharp leading edge of first section 609.

[0071] The length L1 and the angle θ1 can have any of the same dimensions as discussed with reference to Figure 14. The length L3, the length L2, and the angle θ2 can be any dimensions that one of ordinary skill in the art may desire.

[0072] 15 illustrates an embodiment of a cannula 706, which may be the same as or generally similar to the cannula 506 described in connection with FIG. 13 , except as otherwise described herein. The cannula 706 may include a distal end face 707 having a first section 709 disposed generally orthogonally relative to the longitudinal axis of the cannula 706 and a second section 710 disposed at a non-orthogonal angle relative to the longitudinal axis of the cannula 706. The cannula 706 may include one or more rounded edges each located along an intersection between one or more sections of the cannula 706. The one or more rounded edges may provide various advantages, such as minimizing the risk associated with sharp edges (e.g., scraping while advancing the cannula).

[0073] Cannula 706 may include a rounded edge 712 located at the intersection between first section 709 and the sidewall of cannula 706. Rounded edge 712 may extend through the entire thickness of the sidewall of cannula 706. It is contemplated that rounded edge 712 may create a third section of distal end face 707 that is less prominent than deflecting surface 611 of cannula 606. In some cases, rounded edge 712 may extend only partially through the thickness of the sidewall of cannula 706.

[0074] Length L1, length L2, and angle θ may have any dimensions that one skilled in the art would recognize or desire. In one embodiment, any of length L1, length L2, and angle θ may have any of the same dimensions as discussed with reference to FIG. 14 . In an embodiment, length L1 and length L2 may have dimensions such that angle θ may be between 15° and 50°. In one such embodiment, length L1 and length L2 may have dimensions such that angle θ may be between 20° and 30°. In another such embodiment, length L1 may be approximately 1.75 mm, length L2 may be approximately 0.50 mm, and angle θ may be approximately 25° to 26°, e.g., 25.37°. It is contemplated that the angles may be configured in any manner to reduce coring when puncturing tissue.

[0075] Length L2 may contact a desired region of tissue, e.g., the septum, and create a weakness in the septum to deliver energy to the septum and provide entry into the left atrium. It is contemplated that this weakness may allow for puncture either directly from the delivery of energy or through the application of force. Length L1 may be angled away from length L2 to allow for a gradual increase in puncture size. This gradual increase is contemplated to reduce the occurrence of coring when advancing cannula 706 into the left atrium.

[0076] The radius of curvature of rounded edge 712 may be varied in some configurations to minimize any reduction in the length of first section 709 while maintaining the beneficial properties of rounded edge 712. The radius of curvature of rounded edge 712 may be from about 0.05 mm to about 0.25 mm. For example, the radius of curvature of rounded edge 712 may be from about 0.1 mm to about 0.2 mm, or in some cases, about 0.13 mm or about 0.15 mm.

[0077] Cannula 706 may include a rounded edge 713 located at the intersection between first section 709 and second section 710. The radius of curvature of rounded edge 713 may be varied in some configurations to minimize any reduction in the length of first section 709 and / or second section 710 while maintaining the beneficial properties of rounded edge 713. The radius of curvature of rounded edge 713 may be from about 0.05 mm to about 0.25 mm. For example, the radius of curvature of rounded edge 713 may be from about 0.1 mm to about 0.2 mm, or in some cases, about 0.13 mm or about 0.15 mm.

[0078] One or more materials may be selected and / or applied to at least a portion of the distal end face of the cannula to modify various characteristics of the cannula. The following discussion will specifically refer to the embodiment of FIG. 15, but it will be understood that any of the features described in connection with modifying various characteristics of the cannula may be used with any of the embodiments described and / or contemplated herein (e.g., cannulas 306, 406, 506, 606).

[0079] The thermal and / or electrical conductivity of the cannula 706, or in some cases, the distal end surface 707, can be modified through the selection of a particular substrate and / or through the application of a coating to the distal end surface 707. In some embodiments, a material (e.g., gold) having a higher thermal and / or electrical conductivity and / or a different density than the material of the conductive portion of the body of the cannula 706 can be applied as a coating to at least a portion of the distal end surface 707. The increased conductivity of the coating material can advantageously improve the application of thermal and / or electrical therapy to the target tissue. In some cases, the coating material may reduce the power output and / or compressive force required to penetrate the target tissue during use. For example, a material can be selected that has a thermal and / or electrical conductivity that is about 25% to about 50% higher than the cannula body material, which can be stainless steel. In some cases, a material (e.g., silver) having a higher density than the remainder of the body of the cannula 706 can be selected to improve the radiopacity qualities of the distal end surface 707. The increased radiopacity may advantageously improve visualization of distal end face 707 relative to the remainder of the body of cannula 706 during a therapeutic procedure. It will also be appreciated that at least a portion of distal end face 707 may be formed of a material that is more conductive and / or radiopaque relative to the cannula body material, instead of simply applying a coating to distal end face 707.

[0080] In some cases, material properties (e.g., thermal and / or electrical conductivity) may be varied between the first section 709 and the second section 710 of the distal end face 707 to further improve the tissue penetration capabilities of the cannula 706. For example, the first section 709 may include a first material and the second section 710 may include a second material. The first material may have a thermal and / or electrical conductivity that is greater than or less than the thermal and / or electrical conductivity of the second material. The first section 709 may, in some embodiments, include a first coating and / or the second section 710 may include a second coating. In some cases, the first section 709 may include a first coating, while the second section 710 is uncoated. The first coating may have a thermal and / or electrical conductivity that is greater than or less than the thermal and / or electrical conductivity of the exposed surface (e.g., coated or uncoated) of the second section 710. In some cases, only one of the first section 709 or the second section 710 includes a coating with enhanced thermal and / or electrical conductivity properties.

[0081] The tubular cannula may be formed from any material desired by one skilled in the art. In one implementation, the tubular cannula comprises stainless steel. The angled, tissue-dilating end face of the second section 710 comprises an exposed, beveled end face of the stainless steel cannula. In some embodiments, as described herein, the arcuate end face of the first section 709 may be provided with a conductivity-enhancing coating, such as gold. Of course, any material or combination of materials may be utilized, the foregoing being provided as non-limiting examples. The material or combination of materials may have properties related to any of electrical conductivity, high material strength, corrosion resistance, radiopacity, sterilization compatibility, or combinations thereof.

[0082] The coating, in some embodiments, may be configured as an insulating layer on the cannula 706. As previously described, the coating may affect one or more properties of the cannula 706, including, for example, electrical resistance. In some embodiments, the coating may be applied along the cannula 706, except for the distal end face of the cannula 706, to define the electrode tip. In one embodiment, the thickness of the coating may be gradually reduced near the distal end of the cannula 706 to blend with the distal face. In one embodiment, the distal edge of the coating may include a fillet to reduce any sharp edges at the distal end face of the cannula 706. In embodiments, the distal end face and coating of the cannula 706 may be filleted to reduce sharp edges, thus reducing coring and other undesirable trauma at the septum. However, in another embodiment (not shown), the coating and / or distal end face of the cannula may be chamfered or otherwise blended.

[0083] The edges of the coating may be blended according to methods including grinding, laser machining, electrolytic polishing, additive manufacturing, electrical discharge machining, machining, or any other method that may be desired. Any method disclosed herein includes one or more steps or actions for performing the described method. Method steps and / or actions may be interchangeable with one another. In other words, unless a specific order of steps or actions is required for proper operation of an embodiment, the order and / or use of specific steps and / or actions may be modified.

[0084] Throughout this specification, references to approximations are made, such as by use of the terms "about" or "approximately." For each such reference, it should be understood that in some embodiments, the value, feature, or characteristic may be specified without the approximation. For example, when modifiers such as "about," "substantially," and "approximately" are used, these terms include the modified term within their scope even in the absence of those modifiers. For example, when the term "substantially planar" is described with respect to a feature, it is understood that in further embodiments, the feature may have a strictly planar orientation.

[0085] Throughout this specification, a reference to a "particular embodiment," or the like, means that the particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, references to recited phrases or variations thereof found throughout this specification do not necessarily all refer to the same one or more embodiments.

[0086] Similarly, in the above description of embodiments, it should be understood that various features may be grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim requires more features than are expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment.

Claims

1. 1. A transseptal crossing system comprising: a sheath including an elongate tubular sheath body having a sheath lumen extending therethrough; A long tubular body and Equipped with The elongated tubular body an electrically conductive sidewall defining a central lumen, the central lumen configured to receive a guidewire and allow at least a portion of the guidewire to extend through a distal opening in the electrically conductive sidewall; a distal end section including a distal end surface in electrical communication with the electrically conductive sidewall; Equipped with the distal end surface is a first section disposed generally perpendicular to a longitudinal axis of the elongate tubular body; a second section disposed at a non-orthogonal angle relative to the longitudinal axis of the elongated tubular body; and Equipped with At least one of the first section or the second section is configured to deliver energy to a target tissue. Transseptal crossing system.

2. The transseptal crossing system of claim 1 , wherein the first section of the distal end surface has a length that is at least about 20% of a diameter of the distal end section of the elongate tubular body.

3. The transseptal crossing system of claim 1 , wherein the length of the first section is up to about 50% of the diameter of the distal end section of the elongate tubular body.

4. The transseptal crossing system of claim 1 , wherein the length of the first section is about 25% to about 30% of the diameter of the distal end section of the elongate tubular body.

5. The transseptal crossing system of claim 1 , wherein the non-orthogonal angle of the second section is at least about 30°.

6. The transseptal crossing system of claim 1 , wherein the non-orthogonal angle of the second section is at most about 70°.

7. The transseptal crossing system of claim 1 , wherein the non-orthogonal angle of the second section is between about 40° and about 50°.

8. 10. The transseptal crossing system of claim 1, wherein the first section comprises a first material and the second section comprises a second material, the first material having a first conductive property that is different from a second conductive property of the second material.

9. The transseptal crossing system of claim 8 , wherein the first material comprises a coating on the first section.

10. The transseptal crossing system of claim 8 , wherein the second material comprises a coating on the second section.

11. 10. The transseptal crossing system of claim 1, further comprising a dilator configured to be positioned through the sheath lumen, the dilator having a dilator lumen extending through a dilator body, the dilator lumen configured to receive the elongated tubular body.

12. The transseptal crossing system of claim 1 , further comprising a tubular insulating layer surrounding the electrically conductive sidewall and leaving the distal end section exposed.

13. 1. A transseptal crossing system comprising: a sheath including an elongate tubular sheath body having a sheath lumen extending therethrough; A long tubular body and Equipped with The elongated tubular body an electrically conductive sidewall defining a central lumen, the central lumen configured to receive a guidewire and allow at least a portion of the guidewire to extend through a distal opening in the electrically conductive sidewall; a distal end section including a distal end surface in electrical communication with the electrically conductive sidewall; Equipped with the distal end surface is a first material having a first conductive property; a second material having a second conductive property different from the first conductive property; Including, A transseptal crossing system, wherein at least a portion of the distal end section is configured to deliver energy to a target tissue.

14. The transseptal crossing system of claim 13 , wherein the first material comprises a coating on a portion of the distal end surface.

15. The transseptal crossing system of claim 13 , wherein the first material comprises gold.

16. 14. The transseptal crossing system of claim 13, further comprising a dilator configured to be positioned through the sheath lumen, the dilator having a dilator lumen extending through a dilator body, the dilator lumen configured to receive the elongated tubular body.

17. The transseptal crossing system of claim 13 , further comprising a tubular insulating layer surrounding the electrically conductive sidewall and leaving the distal end section exposed.

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