Impedance-controlled RF-transparent perforations

Abstract

To provide an RF ablation system.SOLUTION: An example RF ablation system including a transseptal needle having an ablation electrode thereon can be used to perform a transseptal perforation using RF energy. Ablation energy can be applied and / or terminated based on a change in impedance at the ablation electrode when the electrode comes into or out of contact with tissue. The transseptal needle can further include magnetic field sensors and one or more electrodes. The magnetic field sensors can be positioned proximately to a distal end of the transseptal needle and can be configured to provide location information of the distal end.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to methods and apparatus for performing diagnostic and / or therapeutic procedures on tissues and organs, and more particularly to methods and apparatus for ablation and puncture procedures, such as transseptal puncture procedures that include an ablation step. [Background technology]

[0002] In medical procedures involving a patient's heart, there are numerous diagnostic and therapeutic procedures that involve transseptal left heart catheterization, i.e., catheterization through the left atrium. The transseptal approach provides access for both interventional cardiologists performing antegrade mitral balloon valvuloplasty and cardiac electrophysiologists ablating the left-sided accessory pathway or performing transcatheter atrial fibrillation therapeutic strategies.

[0003] In 15-25% of normal, healthy people, the interatrial septum (IAS) has a patent fossa ovalis or foramen ovale, i.e., a patent foramen ovale (PFO). A PFO is one of three shunts in normal fetal intrauterine blood circulation. The presence of a PFO can allow passage of a guidewire and / or catheter through the right atrium and septum. In patients lacking a viable PFO pathway, a passage can be created by transseptal puncture. The transseptal puncture procedure, if performed improperly, can be difficult and pose a risk of life-threatening complications.

[0004] U.S. Patent Application Publication No. 2004 / 0220471 (incorporated herein by reference and included in the appendix of U.S. Provisional Patent Application No. 63 / 046,266, from which this patent application depends) discloses a method and device for transseptal facilitation using a location system. During transseptal piercing, once the fossa ovalis is located, a penetrating device, such as a HEARTSPAN™ transseptal needle, is delivered to the fossa ovalis through the vasculature via a sheath, such as a PREFACE® sheath. The penetrating device then exits the sheath and punctures the fossa ovalis. (The HEARTSPAN™ transseptal needle and PREFACE® sheath are available from Biosense Webster, a Johnson & Johnson company.)

[0005] U.S. Patent Application Publication No. 2012 / 0232546 (incorporated herein by reference and included in the appendix of U.S. Provisional Patent Application No. 63 / 046,266, on which this patent application depends) discloses a radiofrequency perforation device for transseptal perforation. While perforation using an RF device is optional, the current standard technique for transseptal perforation procedures primarily relies on puncture with a sharp needle tip rather than radiofrequency perforation. RF current is applied to biological tissue, causing it to heat. The higher the RF current density (current per unit area) within the tissue, the higher the resulting temperature. As tissue is ablated, its impedance increases, thereby reducing the current density through the tissue for a given voltage. Increasing the voltage or the duration of the ablation time increases heating not only in the ablated tissue but also via the blood or adjacent structures. Overheating from RF energy can lead to complications such as steam popping, tissue charring, thrombosis, and adhesion of the ablation electrode to the tissue. Therefore, applicants have recognized a need to overcome the current challenges associated with both transseptal puncture and RF ablation. Summary of the Invention [Means for solving the problem]

[0006] An exemplary transseptal needle can include one or more magnetic field sensors and one or more electrodes. The magnetic field sensor can be positioned proximate a distal end of the transseptal needle and can be configured to provide position information of the distal end. The electrode can be positioned proximate the distal end and can be configured to measure impedance indicative of tissue contact. The one or more magnetic field sensors can include a triaxial magnetic field sensor. The one or more magnetic field sensors can include a uniaxial sensor. At least one of the electrodes can be configured to deliver energy from the electrode to tissue as an ablation electrode.

[0007] An exemplary RF ablation system can include a processor, two terminals, and a non-transitory computer-readable medium. The two terminals can include an electrical ablation output terminal and an electrical ablation return terminal. The non-transitory computer-readable medium can be in communication with the processor. The non-transitory computer-readable medium can include instructions that, when executed by the processor, cause the system to monitor a change in electrical impedance between the two terminals while electrical energy is being output from the electrical ablation output terminal, and terminate the output of ablation energy to the ablation output terminal when at least one of the following occurs: (a) the change in electrical impedance between the two terminals exceeds a predetermined impedance difference, and (b) a predetermined time period elapses.

[0008] The non-transitory computer-readable medium may further include instructions that, when executed by the processor, cause the system to detect a decrease in electrical impedance between the two terminals and determine a start time from which the predetermined time is measured based on the detection of the decrease in electrical impedance.

[0009] The predetermined impedance difference can correspond to an increase in electrical impedance between the two terminals. The non-transitory computer-readable medium can further include instructions that, when executed by the processor, cause the system to determine connection of the electrical ablation output terminal to the ablation device and determine a start time from which the predetermined time is measured based on the time when electrical energy is first output from the electrical ablation electrode and the determination of connection of the electrical ablation output terminal to the ablation device.

[0010] The RF ablation system can further include a transseptal needle having an ablation electrode in electrical communication with the electrical ablation output terminal. The transseptal needle can further include a magnetic field sensor disposed proximate a distal end of the transseptal needle.

[0011] The non-transitory computer-readable medium may further include instructions that, when executed by the processor, cause the system to determine, via the magnetic field sensor, the position of the transseptal needle relative to the fossa ovalis.

[0012] The RF ablation system can further include a display configured to provide a visual representation of the fossa ovalis and the position of the transseptal needle relative to the fossa ovalis.

[0013] The predetermined time period may be from about 1 millisecond to about 10 milliseconds.

[0014] The non-transitory computer-readable medium may further include instructions that, when executed by the processor, cause the system to determine that the fossa ovalis has been perforated based on a monitored change in electrical impedance between the two terminals, and to provide an indication that the fossa ovalis has been perforated.

[0015] The non-transitory computer-readable medium may further include instructions that, when executed by the processor, cause the system to determine that the fossa ovalis is incompletely perforated based on the passage of a predetermined amount of time and to provide an indication that the fossa ovalis is perforated.

[0016] The RF ablation system may further include a display configured to provide an indication of perforation of the fossa ovalis.

[0017] An exemplary method of controlling an RF transseptal needle may include one or more of the following steps, performed in various orders, as will be understood by those skilled in the art in light of the teachings herein. The method may include outputting ablation energy to an ablation electrode of the transseptal needle. The method may include measuring impedance through the ablation electrode. The method may include detecting tissue impedance, including electrical impedance through the ablation electrode, while the ablation electrode is positioned within cardiac tissue. The method may include terminating output of ablation energy to the ablation electrode upon the occurrence of at least one of the following: (a) the electrical impedance through the ablation electrode changes from the tissue impedance by a predetermined impedance difference, and (b) a predetermined time period has elapsed. The predetermined time period may be from about 1 millisecond to about 10 milliseconds.

[0018] The method can include measuring a pre-contact impedance, including electrical impedance through the ablation electrode. The method can include detecting a change in impedance through the ablation electrode from the pre-contact impedance to a tissue impedance. The method can include setting a start time at which the predetermined time is measured, such that the start time is based on detecting a change in impedance through the ablation electrode from the pre-contact impedance to the tissue impedance. The method can include detecting a change in tissue impedance contact and post-impedance tissue contact.

[0019] The method can include setting a start time from which the predetermined time is measured based on the time that ablation energy is first output to the ablation electrode.

[0020] The method can include determining a position of the transseptal needle relative to the fossa ovalis via a magnetic sensor in the transseptal needle.

[0021] The method can include providing computer-readable coordinates of a position of the transseptal needle relative to the fossa ovalis.

[0022] The method can include determining that the fossa ovalis has been perforated based on electrical impedance through the ablation electrode. The method can include providing an indication that the fossa ovalis has been perforated.

[0023] The method can include determining that the fossa ovalis is incompletely perforated based on the passage of a predetermined amount of time. The method can include providing an indication that the fossa ovalis is perforated.

[0024] An exemplary method of performing a transseptal puncture procedure may include one or more of the following steps, performed in various orders, as will be understood by those skilled in the art in light of the teachings herein. The method may include contacting the fossa ovalis with a tip of a transseptal needle having an ablation electrode thereon. The method may include electrically ablating the fossa ovalis with the ablation electrode. The method may include penetrating the fossa ovalis while electrically ablating the fossa ovalis. The method may include measuring electrical impedance through the ablation electrode. The method may include detecting tissue impedance, including electrical impedance through the ablation electrode, while the ablation electrode is positioned within tissue of the fossa ovalis. The method may include terminating electrical ablation via the ablation electrode when at least one of the following occurs: (a) the electrical impedance through the ablation electrode changes from the tissue impedance by a predetermined impedance difference, and (b) a predetermined time period has elapsed.

[0025] The method can include measuring a pre-contact impedance, including electrical impedance through the ablation electrode, while the ablation electrode is positioned outside tissue of the fossa ovalis. The method can include detecting a change in impedance through the ablation electrode from the pre-contact impedance to a tissue impedance. The method can include setting a start time at which the predetermined time is measured, such that the start time is based on detecting a change in impedance through the ablation electrode from the pre-contact impedance to a tissue impedance.

[0026] The method can include setting a start time from which the predetermined time is measured based on the time that ablation energy is applied to the ablation electrode.

[0027] The method can include measuring the position of the transseptal needle when the ablation electrode is positioned proximate the fossa ovalis via a magnetic sensor in the transseptal needle.

[0028] The predetermined time period may be from about 1 millisecond to about 10 milliseconds.

[0029] The method can include determining that the fossa ovalis is perforated based on electrical impedance through the ablation electrode.

[0030] The method can include determining that the fossa ovalis is incompletely perforated based on the passage of a predetermined amount of time. [Brief explanation of the drawings]

[0031] [Figure 1] 1 illustrates components of a system for impedance-controlled RF transseptal piercing according to an embodiment of the present invention. [Figure 2] 1 illustrates components of a generator according to an embodiment of the present invention. [Figure 3A] 1 illustrates a sequence of steps for performing a transseptal puncture in accordance with an aspect of the present invention. [Figure 3B] 1 illustrates a sequence of steps for performing a transseptal puncture in accordance with an aspect of the present invention. [Figure 3C] 1 illustrates a sequence of steps for performing a transseptal puncture in accordance with an aspect of the present invention. [Figure 3D] 1 illustrates a sequence of steps for performing a transseptal puncture in accordance with an aspect of the present invention. [Figure 3E] 1 illustrates a sequence of steps for performing a transseptal puncture in accordance with an aspect of the present invention. [Figure 4] FIG. 1 is a flow diagram illustrating a method for performing a transseptal puncture according to an aspect of the present invention. [Figure 5] FIG. 10 is a flow diagram illustrating another method for performing a transseptal puncture, according to an aspect of the present invention. [Figure 6] FIG. 1 is a diagram of a system for impedance-controlled RF transseptal puncture used to carry out a method for performing transseptal puncture according to an embodiment of the present invention. [Figure 7A] 1A-1C are diagrams of an exemplary transseptal needle according to aspects of the present invention. [Figure 7B] 1A-1C are diagrams of an exemplary transseptal needle according to aspects of the present invention. [Figure 7C] 1A-1C are diagrams of an exemplary transseptal needle according to aspects of the present invention. [Figure 8] 10A-10C are diagrams of another exemplary transseptal needle in accordance with aspects of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The term "about" or "approximately" used herein in connection with any numerical value or range of values ​​indicates a suitable dimensional tolerance that enables a portion of a component or a collection of components to function in accordance with its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value, for example, "about 90%" may refer to a range of values ​​of 71% to 99%.

[0033] As used herein, the terms “component,” “module,” “system,” “server,” “processor,” “memory,” etc. are intended to include one or more computer-related units, such as, but not limited to, hardware, firmware, a combination of hardware and software, software, or running software. For example, a component may be, but is not limited to, a process running on a processor, an object, an executable thread of execution, a program, and / or a computer. By way of example, both an application running on a computing device and the computing device may be a component. One or more components may reside within an executing process and / or thread, and a component may be localized on one computer and / or distributed among two or more computers. Furthermore, these components may execute from various computer-readable media having various data structures stored thereon. Components may communicate by local and / or remote processes, such as pursuant to a signal comprising one or more data packets, such as data from one component interacting with another component in a local system, in a distributed system, and / or across a network, such as the Internet, with other systems via a signal. The computer-readable medium may be non-transitory. Non-transitory computer-readable media include, but are not limited to, random access memory (RAM), read-only memory (ROM), electronically erasable programmable ROM (EEPROM), flash memory or other memory technology, compact disc ROM (CD-ROM), digital versatile disc (DVD) or other optical storage device, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device, or any other tangible physical medium that can be used to store computer-readable instructions and / or data.

[0034] As used herein, the term "computing system" is intended to include a standalone machine or apparatus and / or combinations of machines, components, modules, systems, servers, processors, memories, detectors, user interfaces, computing device interfaces, network interfaces, hardware elements, software elements, firmware elements, and other computer-related units. By way of example and not limitation, a computing system may include one or more of a general-purpose computer, a special-purpose computer, a processor, a portable electronic device, a portable electronic medical device, a fixed or semi-fixed electronic medical device, or other electronic data processing device.

[0035] As used herein, the term "non-transitory computer-readable medium" includes, but is not limited to, random access memory (RAM), read-only memory (ROM), electronically erasable programmable ROM (EEPROM), flash memory or other memory technology, compact disc ROM (CD-ROM), digital versatile disc (DVD) or other optical storage device, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device, or any other tangible physical medium that can be used to store computer-readable information.

[0036] As used herein, the term "radiofrequency" (RF) refers to alternating current flowing through a conductor. In the case of ablation, RF current flows through biological tissue and fluids containing free ions. Non-ablated biological tissues include blood or saline solutions, which result in tissues with higher electrical conductivity (lower impedance) compared to ablated tissue.

[0037] As used herein, the terms "tubular" and "tube" are intended to be broadly interpreted and are not limited to right cylindrical structures, structures that are strictly circular in cross section, or structures that are uniform in cross section throughout their length. For example, a tubular structure or tubular system is generally depicted as a substantially right cylindrical structure. However, a tubular system may have a tapered or curved outer surface without departing from the scope of the present disclosure.

[0038] FIG. 1 illustrates a system 100 configured for impedance-controlled RF transseptal piercing. System 100 can include a generator 180, shown in further detail in FIG. 2. The generator can be configured to provide ablation electrical energy (e.g., as an RF electrical signal). System 100 can further include a return pad 198 that can be connected to generator 198 to provide a return path for the ablation electrical energy. Generator 180 can be configured to terminate ablation in response to detecting a change in impedance or the timeout of a preset ablation time limit.

[0039] System 100 can further include a transseptal needle 110. Needle 110 can include an ablation electrode 128 at its distal end, which can be connected to generator 180 to receive ablation electrical energy provided by generator 180. The electrical current can have a high current density at ablation electrode 128 that propagates through the patient's body and can return through a return pad 198. Exemplary configurations of ablation electrode 128 are shown in more detail in FIGS. 7A-7C and 8. Return pad 198 can be positioned and configured to be in contact with the patient over a sufficiently large surface area to avoid having concentrated currents that could otherwise damage patient tissue due to current return.

[0040] During transseptal puncture, needle 110 punctures tissue and exits into the left atrium. The impedance at ablation electrode 128 when it is in contact with tissue is low compared to the impedance at the ablation electrode when it is away from tissue and in contact with blood. When transseptal needle 110 exits the tissue, a sudden increase in impedance can be observed. In some procedures, the change in impedance can occur within milliseconds or less. Therefore, system 100 can be configured to detect impedance changes consistent with this time frame.

[0041] The system 100 can further include a dilator 150 and a pump 170. The transseptal needle 110 and / or the dilator 150 can be connected to the pump 170 to provide irrigation at the treatment site as part of the ablation procedure. The dilator can be sized, shaped, and otherwise configured to deliver the transseptal needle 110 to the fossa ovalis and to dilate the transseptal puncture once created by the transseptal needle 110.

[0042] System 100 can further include a navigation system 160, and transseptal needle 110 can further include one or more magnetic field sensors 120, 122, 124, 126. The configuration of the magnetic field sensors is shown in more detail in Figures 7A-7C and 8. Navigation system 160 can be configured to interpret magnetic field data from the magnetic field sensors to determine the position of transseptal needle 110.

[0043] FIG. 2 illustrates components of generator 180. Generator 180 can include processor 182, memory 184, output ablation terminal 186, and return terminal 188. Generator 180 can be configured to detect a sudden increase in impedance at ablation electrode 128 as the ablation electrode exits tissue. In some embodiments, the generator can be configured via a Carto® system manufactured by Biosense Webster or a similar system. During ablation, output ablation terminal 186 provides ablation energy to ablation electrode 128 of transseptal needle 110, and current focuses on the patient near ablation electrode 128, spreads through the patient's body, exits the patient's body primarily at return pad 198, and returns to return terminal 188 via a wire. Because the current focuses primarily near the ablation electrode, a change in impedance at ablation electrode 128 results in a measurable change in impedance of the path from the output ablation terminal to return terminal 188. By measuring the impedance across the terminals 186, 188, changes in impedance at the ablation electrode 128 can be detected.

[0044] When the ablation electrode is not in contact with tissue, the impedance between the two terminals 186, 188 is greater than when the electrode is in contact with tissue. Therefore, contact of the ablation electrode with tissue can be detected by detecting a decrease in electrical impedance. Similarly, when the ablation needle exits the tissue, the impedance at the ablation electrode increases. Therefore, the predetermined impedance difference relied upon to terminate the ablation current can correspond to an increase in electrical impedance between the two terminals 186, 188.

[0045] Generator 180 can be configured to automatically terminate ablation energy upon a change in impedance across terminals 186, 188. Generator 180 can additionally or alternatively be configured to terminate ablation energy when a predetermined time has elapsed. Generator 180 can be programmed such that memory 184 includes computer-readable instructions stored thereon that, when executed by a processor, cause the system to monitor changes in electrical impedance between terminals 186, 188 during ablation and terminate ablation when at least one of the following occurs: (a) the change in electrical impedance between the two terminals exceeds a predetermined impedance difference, and (b) a predetermined time has elapsed.

[0046] In some embodiments, the start time, which measures the elapsed time to a predetermined time, can be measured from the time the ablation needle contacts the tissue, in which case the generator 180 can be configured to detect a decrease in electrical impedance between the two terminals 186, 188 and determine the start time based on the detection of the decrease in electrical impedance.

[0047] In addition to, or as an alternative to, determining a start time for measuring the time lapse based on the impedance decrease when the ablation electrode contacts tissue, the start time can be based on the time when needle 110 is connected to output terminal 186 and energy is first output from output terminal 186. In this case, memory 184 can include instructions that, when executed by processor 182, cause generator 180 to determine the connection of the electrical ablation output terminal to the ablation device, and to determine a start time, where the predetermined time is measured based on the time when electrical energy is first output from the electrical ablation electrode and the determination of the connection of the electrical ablation output terminal to the ablation device.

[0048] The memory 184 may further include instructions that cause the processor 182 to determine that the fossa ovalis has been perforated based on a monitored change in electrical impedance between the two terminals. The memory 184 may further include instructions that cause the processor 182 to provide an indication that the fossa ovalis has been perforated. The indication may be a visual or audible indication provided to a human user by the generator 180 itself, or a computer-readable indicator (e.g., an electrical signal) that can be interpreted by an ancillary device.

[0049] The memory 184, and likewise the processor 182, need not be located within the generator 180, but can be located on one or more auxiliary computing systems connected to the generator 180 and capable of controlling the generator 180 to terminate ablation, as would be understood by one of ordinary skill in the art with the teachings of the present disclosure. Similarly, the memory 184 and the processor 182 can be distributed among multiple computing systems to achieve the desired functionality, as would be understood by one of ordinary skill in the art with the teachings of the present disclosure.

[0050] Some or all of the functionality of generator 180 as described in connection with FIG. 2 may also be achieved in hardware, as will be understood by those skilled in the art having the benefit of the teachings of this disclosure.

[0051] The memory 184 may include a non-transitory computer-readable medium.

[0052] 3A-3E show a series of steps during a transseptal puncture procedure.

[0053] FIG. 3A shows a dilator 150 traversed through the inferior vena cava 22 and having its distal end positioned near the fossa ovalis 16 .

[0054] 3B shows the transseptal needle 110 being translated through a dilator 150 and approaching the fossa ovalis 16. The dilator 150 and the septum of the fossa ovalis 16 are shown in cross section. As the transseptal needle 110 approaches the fossa ovalis 16, the position of the transseptal needle 110 can be measured via the transseptal needle's magnetic sensors 120, 122, 124, 126 (see FIGS. 7A-7C and 8). When the ablation electrode is positioned outside the tissue of the fossa ovalis 16, pre-contact impedance can be measured via the ablation electrode 128.

[0055] FIG. 3C shows the transseptal needle 110 in contact with the fossa ovalis 16. The ablation electrode 128 of the transseptal needle 110 can be positioned at the distal end 114 of the transseptal needle 110 so as to bring the distal end 114 of the needle 110 into contact with a tissue location and bring the ablation electrode 128 into contact with tissue in the fossa ovalis 16. Near the distal end 114 of the transseptal needle 110, the fossa ovalis 16 is aligned with the parallel axis PP and perpendicular to the transverse axis TP. The transseptal needle 110 is shown at an angle of approximately 45 degrees from the parallel axis PP and the transverse axis TP. Aligning the transseptal needle 110 at an angle closer to the transverse axis TP reduces the likelihood of laceration by the sharp distal tip 114 but may be more difficult to achieve due to anatomical and dilator geometry.

[0056] The impedance at the ablation electrode 128 can be measured while the ablation electrode is in contact with and / or positioned within the tissue (tissue impedance) of the fossa ovalis 16. Contact of the ablation electrode 128 with the tissue can be detected as a change in impedance through the ablation electrode 128 from the pre-contact impedance to the tissue impedance.

[0057] When the transseptal needle 110 is positioned as shown in FIG. 3C , the fossa ovalis can be electrically ablated by the ablation electrode 128. Furthermore, the time when the ablation electrode 128 first contacts tissue in the fossa ovalis 16 can be recorded or otherwise utilized as a starting time used as a reference for terminating the electrical ablation. Alternatively, the starting time can be determined based on the initial application of ablation energy to the ablation electrode 128. The electrical ablation can be terminated when a predetermined time has elapsed after the starting time. In some embodiments, the predetermined time can be set as high as about 2 seconds. However, during most procedures, the crossing can be completed within 1 millisecond, and therefore the predetermined time can be set from about 1 millisecond to about 10 milliseconds.

[0058] 3D shows the transseptal needle 110 partially penetrating the fossa ovalis 16 such that at least a portion of the ablation electrode 128 is positioned within the tissue of the fossa ovalis 16. Ablated tissue 17 is shown around the distal portion 114 of the transseptal needle 110. The fossa ovalis 16 can be ablated by the ablation electrode 128 while penetrated by the transseptal needle 110. The impedance at the ablation electrode 128 can be measured while the ablation electrode 128 is ablating.

[0059] 3E shows that the transseptal needle 110 has completely penetrated the fossa ovalis 16. The ablation electrode 128 is positioned at least partially within the left atrium 14. A change in electrical impedance through the ablation electrode 128 can be detected as the ablation electrode 128 enters the left atrium 14. When the electrical impedance through the ablation electrode 128 changes by a predetermined impedance difference with the tissue impedance, electrical ablation can be terminated.

[0060] In some procedures, a predetermined amount of time may elapse before the fossa ovalis is completely perforated (e.g., at some locations as shown in FIGS. 3B-3D). Exemplary systems disclosed herein can be configured to determine that the fossa ovalis is incompletely perforated based on the passage of the predetermined amount of time. Exemplary systems can further be configured to provide an indication that the fossa ovalis is incompletely perforated.

[0061] In other procedures, the fossa ovalis 16 can be completely perforated, as shown in FIG. 3E. The exemplary systems disclosed herein can be configured to determine that the fossa ovalis 16 has been perforated based on the electrical impedance through the ablation electrodes. The exemplary systems can further be configured to provide an indication that the fossa ovalis has been completely perforated.

[0062] 4 is a flow diagram of a method 400 for performing a transseptal puncture procedure and / or controlling a transseptal needle. The steps of method 400 may be performed in an alternative order, additional steps not shown may be included, and / or variations and substitutions of the steps may be performed as would be understood by one of ordinary skill in the art having the teachings herein.

[0063] In step 402, the fossa ovalis can be contacted with an electrode of a transseptal needle. The transseptal needle can include any exemplary transseptal needle 110 shown or disclosed herein, variations thereof, or alternatives thereof, as would be understood by one of ordinary skill in the art following the teachings herein. The electrode can include any exemplary electrode 128 shown or disclosed herein, variations thereof, or alternatives thereof, as would be understood by one of ordinary skill in the art following the teachings herein.

[0064] In step 404, the fossa ovalis can be electrically ablated, where the transseptal needle contacts tissue in the fossa ovalis. Ablation can be applied using the methods and systems shown or disclosed herein, variations thereof, or alternatives thereof, as will be understood by those skilled in the art from the teachings herein.

[0065] A first electrical impedance can be measured through the ablation electrode in step 406. The first electrical impedance can be a pre-contact impedance measured when the ablation electrode is not in contact with tissue as shown or disclosed herein, or a variation thereof, or an alternative thereof, as will be understood by one of ordinary skill in the art in light of the teachings herein.

[0066] In step 408, the fossa ovalis can be penetrated while electrically ablating the fossa ovalis.

[0067] At step 410, a second electrical impedance can be measured while the tip of the transseptal needle is positioned in the fossa ovalis. The tip can include the distal end 114 of the transseptal needle shown or disclosed herein, variations thereof, or alternatives thereof, as would be understood by one of ordinary skill in the art in light of the teachings herein. The tip can further include an ablation electrode.

[0068] In step 412, electrical ablation can be terminated based on an abrupt impedance change from the second electrical impedance to a third electrical impedance and / or a predetermined time elapsed from a start time marked by an impedance change from the first electrical impedance to the second electrical impedance. The third electrical impedance can be measured when the fossa ovalis is fully penetrated. The third electrical impedance can be measured by any system or method shown or disclosed herein, or variations or alternatives thereof, as will be understood by one of ordinary skill in the art in light of the teachings herein. The tip can further include an ablation electrode. The change in impedance can be an increase in impedance.

[0069] FIG. 5 shows a flow diagram outlining a method 500 for performing a transseptal puncture procedure and / or controlling a transseptal needle.

[0070] In step 502, attachment of the transseptal needle to the ablation energy source (eg, a terminal of a generator) can be detected.

[0071] When the power is turned on, in step 504, ablation energy can be provided to the transseptal needle at a predefined power setting. The power setting can be defined based on the specifics of the ablation procedure.

[0072] The electrical impedance through the transseptal needle can be monitored in step 506. The electrical impedance can be monitored continuously (including at regular intervals) at least until the method 500 ends in step 514.

[0073] If, in step 508, an impedance change is detected as a result of monitoring the impedance in step 506, method 500 may end in step 514. If, in step 508, an impedance change is not detected as a result of monitoring the impedance in step 506, method 500 may proceed to step 510.

[0074] In step 510, the time elapsed since the start time marked by the power being turned on in step 504 can be monitored.

[0075] If the time has elapsed in step 512, the method 500 may end in step 514. If the time has not elapsed in step 512, the method 500 may return to step 506 to continue monitoring the electrical impedance.

[0076] In step 514, power to the transseptal needle can be terminated to stop the ablation.

[0077] Some or all of the steps of methods 400, 500 shown in Figures 4 and 5 can be performed by a computing device or system. For example, the steps can be performed by one or more components of system 100 shown in Figure 1. Preferably, the steps can be programmed into memory 184 of generator 180 and executed by processor 182 such that generator 180 controls the RF transseptal needle as outlined in methods 400, 500. Additionally or alternatively, some or all of the steps can be included as instructions in memory on a computing device or system in communication with generator 180, as will be understood by those skilled in the art from the teachings herein.

[0078] FIG. 6 is a diagram of a system 20 for impedance-controlled RF transseptal puncture used to implement a method for performing a transseptal puncture. The system 20 can be used during a medical procedure on the heart 22 of a patient 24 to perform a transseptal puncture. The procedure can be performed by one or more operators, including a medical professional 26. The system 20 can be configured to present an image of a cavity, such as a lumen, of the heart 22, allowing the operator 26 to visualize features of the cavity. The system 20 can be further configured to present an image of the dilator 150 and / or the transseptal needle 110. The system 20 can further include or be configured to control components of the system 100 shown in FIG. 1.

[0079] System 20 may be controlled by a system processor 30, which may be implemented as a general-purpose computer. Processor 30 may be mounted within a console 40. Console 40 may include operating controls 42, such as a keypad and a pointing device, such as a mouse or trackball, that an operator 26 may use to interact with processor 30. Results of operations performed by processor 30 may be provided to the operator on a display 44 connected to processor 30. Display 44 may further present the operator with a graphic user interface that enables the operator to control system 20. Operator 26 may be configured to use controls 42 to input values ​​for parameters used by processor 30 in the operation of system 20.

[0080] Processor 30 uses computer software to operate system 20. This software may be downloaded to processor 30 in electronic form, for example over a network, or alternatively or additionally may be provided and / or stored on a non-transitory, tangible computer-readable medium, such as magnetic, optical, or electronic memory.

[0081] In operation of the system 20, the professional 26 inserts the catheter 60 into the patient 24 so that the distal end of the catheter enters the left atrium 16 of the patient's heart via the inferior vena cava 22. The professional 26 delivers the dilator 150 and the transseptal needle 110 through the catheter 60 into the left atrium 16. The processor 30 can be configured to track both the position and orientation of the distal end 114, typically the distal tip, of the transseptal needle 110 while within the heart 10. The transseptal needle 110 can include a tracking coil at its distal end. The processor 30 can utilize a magnetic tracking system such as that provided by the Carto® system manufactured by Biosense Webster. The system 20 can include an operating magnetic field transmitter 66 near the patient 24 such that a magnetic field from the transmitter interacts with one or more tracking coils at the distal end 114 of the transseptal needle 110. The coils interacting with the magnetic field generate signals that are transmitted to the processor 30, which analyzes the signals to determine the position and orientation of the transseptal needle 110. Using the tracking coils and magnetic tracking system, the dilator 150 and transseptal needle 110 can be positioned as shown in Figures 3A and 3B.

[0082] The processor 40 may be further configured to control ablation energy to the transseptal needle 110 as shown and described in connection with FIGS. 1, 2, 3C-3E, 4, and 5.

[0083] 7A-7C are diagrams of exemplary transseptal needles 110a-c that can be used in place of the transseptal needle 110 shown in Figures 1, 3A-3E, and 6. Each transseptal needle 110a, 110b, 110c includes a tubular body 130 aligned along a longitudinal axis LL. The needles 110a-c can further include an electrically insulating covering 132, such as a coating or sheath.

[0084] The illustrated transseptal needles 110a, 110b, and 110c each include alternative tip shapes at their respective distal ends 114a, 114b, and 114c. FIG. 7A illustrates a closed, sharp tip shape at the distal end 114a of the transseptal needle 110a. The sharp tip shape can aid in piercing tissue. FIG. 7B illustrates a rounded, atraumatic tip shape at the distal end 114b of the transseptal needle 110b. The atraumatic tip shape can reduce the likelihood of tissue puncture by the transseptal needle 110b without the application of ablative energy. The ablative energy alone may be sufficient to pierce the fossa ovalis without the need for a sharp tip.

[0085] FIG. 7C shows the open distal end 114a with an opening to a lumen 116c through the tubular body 130. The lumen 116c can be shaped to allow for the introduction of fluid to the treatment site. Fluid can be delivered in a manner similar to that disclosed in U.S. Pat. No. 9,326,813, which is incorporated herein by reference in its entirety and included in the appendix to U.S. Provisional Patent Application No. 63 / 046,266, from which this patent application depends. The transseptal needles 110a, 110b shown in FIGS. 7A and 7B also include irrigation ports 116a, 116b that exit from the sides of the needles 110a, 110b rather than from the tips 114a, 114b. The irrigation lumen 116c and ports 116a, 116b provide fluid access to the treatment site. In a transseptal puncture, lumen 116c and ports 116a, 116b can be utilized for sensing pressure within the atrium, injecting contrast media, and other such procedural steps.

[0086] The illustrated transseptal needles 110a, 110b, 110c can include navigational sensors 120, 122, 124, 126 disposed along the tubular body. The navigational sensors can include one or more triaxial sensors and one or more single-axis sensors. Preferably, the transseptal needles 110a, 110b, 110c include a distal triaxial sensor (TAS) 120 near the distal end 114a, 114b, 114c of the transseptal needle 110a, 110b, 110c, and three single-axis sensors (SAS) 122, 124, 126 positioned proximally relative to the distal TAS 120. Preferably, the three SASs 122, 124, 126 are positioned and aligned to collectively function as a TAS. Each sensor 120, 122, 124, 126 includes a tracking coil that can be used with the navigation system 20 to determine the position of the transseptal needle 110, 110a-c, as described in connection with FIG.

[0087] FIG. 8 is a diagram of another exemplary transseptal needle 110d having features similar to those disclosed in U.S. Pat. No. 9,326,813, which is incorporated herein by reference in its entirety and included in the appendix of U.S. Provisional Patent Application No. 63 / 046,266, to which this patent application depends. The needle 110d can be part of a needle electrode assembly 140. The needle 110d is shown to have a tip 114b similar to that shown in FIG. 7B, which is atraumatic. The irrigation port 116 shown in FIG. 8 is positioned on the side of the needle 110d rather than at the distal tip 114b, as disclosed in U.S. Pat. No. 9,326,813. The needle electrode assembly 140 can be delivered through a dilator 150, as shown in FIGS. 3A-3E. The illustrated needle electrode assembly 140 includes a proximal tube 136 that is joined directly or indirectly to the tubular body of the needle 110d (e.g., by a small piece of intermediate tube 146) and is generally more flexible than the tubular body of the needle 110d. A needle electrode lead wire 138 is electrically connected to the needle 110d at its distal end for supplying ablation energy to the needle 110d. The needle 110d is shown having a thermocouple 134 thereon that is connected to a copper wire 142 and a constantan wire 144. A spacer 146 can be positioned or otherwise configured to prevent bodily fluids from entering the distal end of the needle electrode assembly 140. An outer plastic tube 148 protects the wires 142, 144, and 138.

[0088] The devices, systems, and methods disclosed herein can utilize additional structures and functionality, such as additional sensors configured to measure properties of the heart 10. Examples of such sensors include one or more electrodes disposed on the intravascular device to measure electrical potentials, force sensors, and thermocouples.

[0089] The devices, systems, and methods disclosed herein are not limited to transseptal puncture and can be utilized for other suitable procedures as would be understood by one of ordinary skill in the art in light of the teachings herein. For example, some devices, systems, and methods may be utilized in a similar manner for epicardial access.

[0090] The descriptions contained herein are examples of embodiments of the present invention and are not intended to limit the scope of the present invention in any way. As described herein, the present invention contemplates many variations and modifications of ablation and diagnostic tools, including alternative tip shapes, alternative numbers of electrodes, alternative navigation sensors, combinations of components shown in separate figures, alternative materials, alternative component geometries, and alternative component arrangements. Modifications and modifications obvious to those skilled in the art from the teachings of the present disclosure are intended to be within the scope of the following claims.

[0091] [Embodiment] (1) An RF ablation system, comprising: a processor; two terminals comprising an electrical ablation output terminal and an electrical ablation return terminal; a non-transitory computer-readable medium in communication with the processor, which, when executed by the processor, provides the system with: monitoring a change in electrical impedance between the two terminals while electrical ablation energy is being output from the electrical ablation output terminal; below: (a) the change in electrical impedance between the two terminals exceeds a predetermined impedance difference; and (b) the lapse of a prescribed period of time; and a non-transitory computer-readable medium comprising instructions for terminating the electrical ablation energy output to the ablation output terminal when at least one of the following occurs: (2) When the non-transitory computer-readable medium is executed by the processor, the non-transitory computer-readable medium causes the system to: detecting a decrease in the electrical impedance between the two terminals; determining a start time at which the predetermined time is measured based on the detection of the decrease in the electrical impedance; 2. The RF ablation system of claim 1, wherein the predetermined impedance difference corresponds to an increase in the electrical impedance between the two terminals. (3) When the non-transitory computer-readable medium is executed by the processor, the non-transitory computer-readable medium causes the system to: determining a connection of the electrical ablation output terminal to an electrical ablation electrode of an ablation device; An RF ablation system as described in embodiment 1, further comprising instructions for determining a start time from which the predetermined time is measured based on the time when electrical energy is first output from the electrical ablation electrode and a determination of the connection of the electrical ablation output terminal to the ablation device. (4) Furthermore, 2. The RF ablation system of claim 1, comprising a transseptal needle comprising an ablation electrode in electrical communication with the electrical ablation output terminal. (5) The RF ablation system of embodiment 4, wherein the transseptal needle further comprises a magnetic field sensor positioned adjacent to the distal end of the transseptal needle.

[0092] (6) When the non-transitory computer-readable medium is executed by the processor, the non-transitory computer-readable medium causes the system to: An RF ablation system as described in embodiment 5, further comprising instructions for determining the position of the transseptal needle relative to the fossa ovalis via the magnetic field sensor. (7) Furthermore, An RF ablation system as described in embodiment 6, comprising a display configured to provide a visual representation of the fossa ovalis and the position of the transseptal needle relative to the fossa ovalis. (8) An RF ablation system as described in embodiment 1, wherein the predetermined time is from about 1 millisecond to about 10 milliseconds. (9) When the non-transitory computer-readable medium is executed by the processor, the system: determining that the fossa ovalis has been perforated based on a monitored change in electrical impedance between the two terminals; 2. The RF ablation system of claim 1, further comprising instructions for providing an indication that the fossa ovalis is perforated. (10) When the non-transitory computer-readable medium is executed by the processor, the system: determining that the fossa ovalis is incompletely perforated based on the passage of the predetermined time; 2. The RF ablation system of claim 1, further comprising instructions for providing an indication that the fossa ovalis has been perforated.

[0093] (11) Furthermore, An RF ablation system as described in embodiment 1, comprising a display configured to provide an indication of perforation of the fossa ovalis. (12) A method for controlling an RF transseptal needle, comprising: delivering ablation energy to an ablation electrode of the transseptal needle; measuring impedance through the ablation electrode; detecting tissue impedance including the electrical impedance through the ablation electrode while the ablation electrode is positioned in cardiac tissue; below: (a) the electrical impedance through the ablation electrode is changed by a predetermined impedance difference with the tissue impedance; and (b) the lapse of a prescribed period of time; and terminating the output of the ablation energy to the ablation electrode upon the occurrence of at least one of: (13) Furthermore, measuring a pre-contact impedance including the electrical impedance through the ablation electrode while the ablation electrode is positioned outside the cardiac tissue; detecting a change in the impedance through the ablation electrode from the pre-contact impedance to the tissue impedance; setting a start time at which the predetermined time is measured based on the detection of the change in impedance through the ablation electrode from the pre-contact impedance to the tissue impedance. (14) Furthermore, 13. The method of claim 12, further comprising setting a start time from which the predetermined time is measured based on the time the ablation energy is first output to the ablation electrode. (15) Furthermore, 13. The method of claim 12, comprising determining a position of the transseptal needle relative to the fossa ovalis via a magnetic sensor in the transseptal needle.

[0094] (16) Furthermore, 16. The method of embodiment 15, comprising providing computer-readable coordinates of the position of the transseptal needle relative to the fossa ovalis. (17) The method of any one of embodiments 12, wherein the predetermined time is from about 1 millisecond to about 10 milliseconds. (18) Furthermore, determining that the fossa ovalis is perforated based on the electrical impedance through the ablation electrode; providing an indication that the fossa ovalis has been perforated. (19) Furthermore, determining that the fossa ovalis is incompletely perforated based on the passage of the predetermined time; providing an indication that the fossa ovalis has been perforated. (20) A method of performing a transseptal puncture procedure, comprising: contacting the fossa ovalis with a tip of a transseptal needle having an ablation electrode thereon; electrically ablating the fossa ovalis with the ablation electrode; penetrating the fossa ovalis while electrically ablating the fossa ovalis; measuring electrical impedance through the ablation electrode; detecting tissue impedance including the electrical impedance through the ablation electrode while the ablation electrode is positioned within tissue of the fossa ovalis; below: (a) the electrical impedance through the ablation electrode is changed by a predetermined impedance difference with the tissue impedance; and (b) the lapse of a prescribed period of time; and terminating electrical ablation via the ablation electrode upon the occurrence of at least one of:

Claims

1. 1. An RF ablation system comprising: an ablation electrode; a processor; two terminals comprising an electrical ablation output terminal and an electrical ablation return terminal; a non-transitory computer-readable medium in communication with the processor, the non-transitory computer-readable medium, when executed by the processor, for providing the RF ablation system with: monitoring a change in electrical impedance between the two terminals while electrical ablation energy is being output from the electrical ablation output terminal; below: (a) the ablation electrode exiting the target tissue causes an increase in electrical impedance between the two terminals to exceed a predetermined difference; or (b) a predetermined time has elapsed since detecting a decrease in electrical impedance between the two terminals due to contact of the ablation electrode with the target tissue; and a non-transitory computer-readable medium comprising instructions for terminating the electrical ablation energy output to the electrical ablation output terminal upon the first occurrence of

2. Furthermore, The RF ablation system of claim 1 , comprising a transseptal needle comprising an ablation electrode in electrical communication with the electrical ablation output terminal.

3. The RF ablation system of claim 2 , wherein the transseptal needle further comprises a magnetic field sensor positioned proximate a distal end of the transseptal needle.

4. The non-transitory computer-readable medium, when executed by the processor, provides the system with:

4. The RF ablation system of claim 3, further comprising instructions for determining, via the magnetic field sensor, a position of the transseptal needle relative to the fossa ovalis.

5. Furthermore, 5. The RF ablation system of claim 4, comprising a display configured to provide a visual representation of the fossa ovalis and the position of the transseptal needle relative to the fossa ovalis.

6. The RF ablation system of claim 1 , wherein the predetermined time is between 1 millisecond and 10 milliseconds.

7. The non-transitory computer-readable medium, when executed by the processor, provides the system with: determining whether the fossa ovalis has been perforated based on the monitored change in electrical impedance between the two terminals; 10. The RF ablation system of claim 1, further comprising instructions to provide an indication that the fossa ovalis is perforated.

8. Furthermore, 10. The RF ablation system of claim 1, comprising a display configured to provide an indication of perforation of the fossa ovalis.

9. 1. A method of controlling an RF transseptal needle, comprising: delivering ablation energy to an ablation electrode of the transseptal needle; measuring impedance through the ablation electrode; detecting tissue impedance while the ablation electrode is positioned within cardiac tissue; below: (a) the ablation electrode exiting the target tissue causes the impedance through the ablation electrode to increase by a predetermined difference from the tissue impedance; or (b) a predetermined time has elapsed since detecting a decrease in impedance through the ablation electrode due to contact of the ablation electrode with the target tissue; and terminating the output of the ablation energy to the ablation electrode upon first occurrence of

10. Furthermore, 10. The method of claim 9, comprising determining a position of the transseptal needle relative to the fossa ovalis via a magnetic sensor in the transseptal needle.

11. Furthermore, The method of claim 10, comprising providing computer-readable coordinates of the position of the transseptal needle relative to the fossa ovalis.

12. The method of claim 9 , wherein the predetermined time period is between 1 millisecond and 10 milliseconds.

13. Furthermore, determining whether the fossa ovalis is perforated based on impedance through the ablation electrode; providing an indication that the fossa ovalis has been perforated.

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