It is generally known that ablation therapy may be used to treat various conditions afflicting the human anatomy. For example, ablation therapy may be used in the treatment of atrial arrhythmias. When tissue is ablated, or at least subjected to ablative energy generated by an ablation generator and delivered by an ablation catheter, lesions form in the tissue. Electrodes mounted on or in ablation catheters are used to create tissue apoptosis in cardiac tissue to correct conditions such as atrial arrhythmia (including, but not limited to, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter).
Arrhythmia (i.e., irregular heart rhythm) can create a variety of dangerous conditions including loss of synchronous atrioventricular contractions and stasis of blood flow which can lead to a variety of ailments and even death. It is believed that the primary cause of atrial arrhythmia is stray electrical signals within the left or right atrium of the heart. The ablation catheter imparts ablative energy (e.g., radiofrequency energy, cryoablation, lasers, chemicals, high-intensity focused ultrasound, etc.) to cardiac tissue to create a lesion in the cardiac tissue. This lesion disrupts undesirable electrical pathways and thereby limits or prevents stray electrical signals that lead to arrhythmias.
Electroporation is a non-thermal ablation technique that involves applying strong electric-fields that induce pore formation in the cellular membrane. The electric field may be induced by applying a relatively short duration pulse which may last, for instance, from a nanosecond to several milliseconds. Such a pulse may be repeated to form a pulse train. When such an electric field is applied to tissue in an in vivo setting, the cells in the tissue are subjected to trans-membrane potential, which opens the pores on the cell wall. Electroporation may be reversible (i.e., the temporally-opened pores will reseal) or irreversible (i.e., the pores will remain open). For example, in the field of gene therapy, reversible electroporation (i.e., temporarily open pores) is used to transfect high molecular weight therapeutic vectors into the cells. In other therapeutic applications, a suitably configured pulse train alone may be used to cause cell destruction, for instance by causing irreversible electroporation.
For catheters used to deliver bipolar energy using irreversible electroporation (IRE) or pulsed field ablation (PFA) it is important to provide sufficient electrical isolation and dielectric strength resistance between different electrical wires routed through such catheters. For example, a catheter may include a plurality of electrodes, and a pair of those electrodes may function as an electrical bipole pair. In such circumstances, it is important to electrically isolate the electrical wire connected to a first electrode of the pair from the electrical wire connected to the second electrode of the pair.
In one aspect, an electroporation catheter is provided. The catheter includes a shaft, and a variable diameter loop coupled to a distal end of the shaft, the variable diameter loop including a plurality of electrodes. The catheter further includes a plurality of electrical wires connected to the plurality of electrodes and extending through the variable diameter loop and the shaft, the plurality of electrical wires configured to energize the plurality of electrodes, and a multi-lumen arrangement extending through at least a portion of at least one of the shaft and the variable diameter loop. The multi-lumen arrangement includes a first lumen housing a first subset of the plurality of electrical wires, and a second lumen housing a second subset of the plurality of electrical wires.
In another aspect, an electroporation catheter is provided. The catheter includes a variable diameter loop coupled to a distal end of the shaft, the variable diameter loop including a plurality of electrodes, and a plurality of electrical wires connected to the plurality of electrodes and extending through the variable diameter loop and the shaft, the plurality of electrical wires configured to energize the plurality of electrode. The catheter further includes a tubing arrangement extending through at least a portion of at least one of the shaft and the variable diameter loop, the tubing arrangement including a first tube housing a first subset of the plurality of electrical wires, wherein a second subset of the plurality of electrical wires are outside of the first tube and physically isolated from the first subset of the plurality of electrical wires.
In yet another aspect, a method of assembling an electroporation catheter is provided. The method includes coupling a shaft to a variable diameter loop, the variable diameter loop including a plurality of electrodes, connecting a plurality of electrical wires to the plurality of electrodes, the plurality of electrical wires extending through the variable diameter loop and the shaft, the plurality of electrical wires configured to energize the plurality of electrodes, and implementing at least one of a multi-lumen arrangement and a tubing arrangement to physically isolate a first subset of the plurality of electrical wires from a second subset of the plurality of electrical wires.
The foregoing and other aspects, features, details, utilities and advantages of the present disclosure will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.
Systems and methods for electroporation catheters are provided herein. An electroporation catheter includes a shaft, and a variable diameter loop coupled to a distal end of the shaft, the variable diameter loop including a plurality of electrodes. The catheter further includes a plurality of electrical wires connected to the plurality of electrodes and extending through the variable diameter loop and the shaft, the plurality of electrical wires configured to energize the plurality of electrodes, and a multi-lumen arrangement extending through at least a portion of at least one of the shaft and the variable diameter loop. The multi-lumen arrangement includes a first lumen housing a first subset of the plurality of electrical wires, and a second lumen housing a second subset of the plurality of electrical wires.
Although an exemplary embodiment of the present disclosure is described with respect to pulmonary vein isolation (PVI), it is contemplated that the described features and methods of the present disclosure as described herein may be incorporated into any number of systems and any number of applications as would be appreciated by one of ordinary skill in the art based on the disclosure herein.
System 10 may be used for irreversible electroporation (IRE) to destroy tissue. In particular, system 10 may be used for electroporation-induced primary apoptosis therapy, which refers to the effects of delivering electrical current in such a manner as to directly cause an irreversible loss of plasma membrane (cell wall) integrity leading to its breakdown and cell apoptosis. This mechanism of cell death may be viewed as an “outside-in” process, meaning that the disruption of the outside wall of the cell causes detrimental effects to the inside of the cell. Typically, for classical plasma membrane electroporation, electric current is delivered as a pulsed electric field in the form of short-duration pulses (e.g., having a 0.1 to 20 millisecond (ms) duration) between closely spaced electrodes capable of delivering an electric field strength of about 0.1 to 1.0 kilovolts/centimeter (kV/cm). System 10 may be used, for example, with a high output loop catheter (See
In one embodiment, all electrodes of the loop catheter deliver an electric current simultaneously. Alternatively, in other embodiments, stimulation is delivered between pairs of electrodes on the loop catheter. Delivering electric current simultaneously using a plurality of electrodes arranged in a circular fashion facilitates creating a sufficiently deep lesion for electroporation. To facilitate activating electrodes simultaneously, the electrodes may be switchable between being connected to a 3D mapping system and being connected to EP amplifiers. For a loop catheter, when the loop diameter is minimized, multiple electrodes may overlap with one another.
Irreversible electroporation through a multi-electrode loop catheter may enable pulmonary vein isolation in as few as one shock per vein, which may produce much shorter procedure times compared to sequentially positioning a radiofrequency (RF) ablation tip around a vein.
It should be understood that while the energization strategies are described as involving DC pulses, embodiments may use variations and remain within the spirit and scope of the disclosure. For example, exponentially-decaying pulses, exponentially-increasing pulses, and combinations may be used. Further, in some embodiments, AC pulses may be used.
Further, it should be understood that the mechanism of cell destruction in electroporation is not primarily due to heating effects, but rather to cell membrane disruption through application of a high-voltage electric field. Thus, electroporation may avoid some possible thermal effects that may occur when using radio frequency (RF) energy. This “cold therapy” thus has desirable characteristics.
With this background, and now referring again to
Electroporation generator 26 is configured to energize the electrode element(s) in accordance with an electroporation energization strategy, which may be predetermined or may be user-selectable. For electroporation-induced primary apoptosis therapy, generator 26 may be configured to produce an electric current that is delivered via electrode assembly 12 as a pulsed electric field in the form of short-duration DC pulses (e.g., a nanosecond to several milliseconds duration, a 0.1 to 20 ms duration, or any duration suitable for electroporation) between closely spaced electrodes capable of delivering an electric field strength (i.e., at the tissue site) of about 0.1 to 1.0 kV/cm. The amplitude and pulse duration needed for irreversible electroporation are inversely related. As pulse durations are decreased, the amplitude must be increased to achieve electroporation.
Electroporation generator 26, sometimes also referred to herein as a DC energy source, is a monophasic electroporation generator 26 configured to generate a series of DC energy pulses that all produce current in the same direction. In other embodiments, electroporation generator is biphasic or polyphasic electroporation generator configured to produce DC energy pulses that do not all produce current in the same direction. In some embodiments, for example, the electroporation generator 26 is configured to deliver a biphasic, symmetric pulse signal in which a first (e.g., positive) phase of the signal has the same or similar voltage amplitude and pulse duration as the second (i.e., negative) phase of the signal. In other embodiments, the electroporation generator 26 is configured to deliver a biphasic, asymmetric pulse signal in which a first (e.g., positive) phase of the signal has a different voltage amplitude and/or duration as the second (i.e., negative) phase of the signal. Several exemplary electroporation energization schemes are described in U.S. application Ser. No. 17/247,198, filed on Dec. 3, 2020, the contents of which are incorporated herein by reference in its entirety.
In some embodiments, electroporation generator 26 is configured to output energy in DC pulses at selectable energy levels, such as fifty joules, one hundred joules, two hundred joules, and the like. Other embodiments may have more or fewer energy settings and the values of the available setting may be the same or different. For successful electroporation, some embodiments utilize the two hundred joule output level. For example, electroporation generator 26 may output a DC pulse having a peak magnitude from about 300 Volts (V) to about 3,200 V at the two hundred joule output level. In some embodiments, the peak magnitude may be even larger (e.g., on the order of 10,000 V). Other embodiments may output any other suitable positive or negative voltage. For example, in some embodiments, the systems and methods described herein may include pulses with amplitudes from about 500 V to about 4,000 V, with pulse widths from about 200 nanoseconds to about 20 microseconds.
In some embodiments, a variable impedance 27 allows the impedance of system 10 to be varied to limit arcing. Moreover, variable impedance 27 may be used to change one or more characteristics, such as amplitude, duration, pulse shape, and the like, of an output of electroporation generator 26. Although illustrated as a separate component, variable impedance 27 may be incorporated in catheter 14 or generator 26.
With continued reference to
In the illustrative embodiment, catheter 14 includes a cable connector or interface 40, a handle 42, and a shaft 44 having a proximal end 46 and a distal 48 end. Catheter 14 may also include other conventional components not illustrated herein such as a temperature sensor, additional electrodes, and corresponding conductors or leads. Connector 40 provides mechanical and electrical connection(s) for cable 56 extending from generator 26. Connector 40 may include conventional components known in the art and as shown is disposed at the proximal end of catheter 14.
Handle 42 provides a location for the clinician to hold catheter 14 and may further provide means for steering or the guiding shaft 44 within body 17. For example, handle 42 may include means to change the length of a guidewire extending through catheter 14 to distal end 48 of shaft 44 or means to steer shaft 44. Moreover, in some embodiments, handle 42 may be configured to vary the shape, size, and/or orientation of a portion of the catheter, and it will be understood that the construction of handle 42 may vary. In an alternate embodiment, catheter 14 may be robotically driven or controlled. Accordingly, rather than a clinician manipulating a handle to advance/retract and/or steer or guide catheter 14 (and shaft 44 thereof in particular), a robot is used to manipulate catheter 14. Shaft 44 is an elongated, tubular, flexible member configured for movement within body 17. Shaft 44 is configured to support electrode assembly 12 as well as contain associated conductors, and possibly additional electronics used for signal processing or conditioning. Shaft 44 may also permit transport, delivery and/or removal of fluids (including irrigation fluids and bodily fluids), medicines, and/or surgical tools or instruments. Shaft 44 may be made from conventional materials such as polyurethane and defines one or more lumens configured to house and/or transport electrical conductors, fluids or surgical tools, as described herein. Shaft 44 may be introduced into a blood vessel or other structure within body 17 through a conventional introducer. Shaft 44 may then be advanced/retracted and/or steered or guided through body 17 to a desired location such as the site of tissue 16, including through the use of guidewires or other means known in the art.
In some embodiments, catheter 14 is a loop catheter having catheter electrodes (not shown in
Localization and navigation system 30 may be provided for visualization, mapping and navigation of internal body structures. Localization and navigation system 30 may include conventional apparatus known generally in the art (e.g., an EnSite Precision™ System, commercially available from Abbott Laboratories. and as generally shown with reference to commonly assigned U.S. Pat. No. 7,263,397 titled “Method and Apparatus for Catheter Navigation and Location and Mapping in the Heart,” the entire disclosure of which is incorporated herein by reference). It should be understood, however, that this system is an example only, and is not limiting in nature. Other technologies for locating/navigating a catheter in space (and for visualization) are known, including for example, the CARTO navigation and location system of Biosense Webster, Inc., the Rhythmia® system of Boston Scientific Schimed, Inc., the KODEX® system of Koninklijke Philips N.V., the AURORA® system of Northern Digital Inc., commonly available fluoroscopy systems, or a magnetic location system such as the gMPS system from Mediguide Ltd. In this regard, some of the localization, navigation and/or visualization system would involve a sensor be provided for producing signals indicative of catheter location information, and may include, for example one or more electrodes in the case of an impedance-based localization system, or alternatively, one or more coils (i.e., wire windings) configured to detect one or more characteristics of a magnetic field, for example in the case of a magnetic-field based localization system. As yet another example, system 10 may utilize a combination electric field-based and magnetic field-based system as generally shown with reference to U.S. Pat. No. 7,536,218 entitled “Hybrid Magnetic-Based and Impedance Based Position Sensing,” the disclosure of which is incorporated herein by reference in its entirety.
Variable diameter loop 150 is selectively transitionable between an expanded (also referred to as “open”) diameter 160 (shown in
In the embodiment shown, variable diameter loop 150 includes fourteen catheter electrodes 144 substantially evenly spaced around the circumference of variable diameter loop 150 in the expanded configuration. In the retracted configuration, one or more of electrodes 144 may overlap.
Catheter electrodes 144 are platinum ring electrodes configured to conduct and/or discharge electrical current in the range of one thousand volts and/or ten amperes. In other embodiments, variable diameter loop 150 may include any suitable number of catheter electrodes 144 made of any suitable material. Catheter electrodes 144 may include any catheter electrode suitable to conduct high voltage and/or high current (e.g., in the range of one thousand volts and/or ten amperes). Each catheter electrode 144 is separated from each other catheter electrode by an insulated gap 152. In the example embodiment, each catheter electrode 144 has a same length 164 (shown in
Diameter 160 and catheter electrode 144 spacing may be developed to provide a targeted range of energy density to tissue, as well as to provide sufficient electroporation coverage for different human anatomic geometries. In general, a sufficient number of electrodes 144 with appropriate lengths 164 are desired to provide substantially even and continuous coverage around the circumference of variable diameter loop 150, while still allowing enough flexibility to allow variable diameter loop 150 to expand and contract to vary diameter 160 to the desired extremes.
As mentioned above, length 164 of catheter electrodes 144 may be varied. Increasing length 164 of catheter electrodes 144 may increase coverage of electrodes 144 around the circumference of variable diameter loop 150 while also decreasing current density (by increasing the surface area) on electrodes 144, which may help prevent arcing during electroporation operations. Increasing length 164 too much, however, may prevent variable diameter loop 150 from forming a smooth circular shape and may limit the closed diameter 160 of variable diameter loop 150. Additionally, too great a length 164 may increase the surface area of catheter electrodes 144 to a point that the current density applied to catheter electrodes 144 by a power source is below the minimum current density needed for successful therapy. Conversely, decreasing length 164 decreases the surface area, thereby increasing the current density (assuming no other system changes) on catheter electrodes 144. As discussed above, greater current densities may lead to increased risk of arcing during electroporation, and may result in larger additional system resistances needing to be added to prevent arcing. Moreover, in order to get a desired, even coverage about the circumference of variable diameter loop 150, more catheter electrodes 144 may be needed if length 164 is decreased. Increasing the number of catheter electrodes 144 on variable diameter loop 150 may prevent variable diameter loop 150 from being able to be contracted to a desired minimum diameter 160.
Pulsed field ablation (PFA) has been shown to be an effective form of ablation for treatment of cardiac arrhythmias, particularly for instantaneous pulmonary vein isolation (PVI). PFA includes delivering high voltage pulses from electrodes disposed on a catheter (e.g., including variable diameter loop 150). In PFA, for example, voltage amplitudes may range from about 300 V to at least 3,200 V (or even as large as on the order as 10,000 V), and pulse widths may from hundreds of nanoseconds to tens of milliseconds.
These electric fields may be applied between adjacent electrodes (in a bipolar approach) or between a one or more electrodes and a return patch (in a monopolar approach). There are advantages and disadvantages to each of these approaches (e.g., when using variable diameter loop 150).
For lesion size and proximity, the monopolar approach has a wider range of effect, and can potentially create deeper lesions with the same applied voltage. Further, the monopolar approach may be able to create lesions from a distance (e.g., generally proximate, but not necessarily contacting tissue). The bipolar approach may create smaller lesions, requiring closer proximity or contact with tissue to create transmural lesions. However, the monopolar approach may create larger lesions than are necessary, while the lesions generated using the bipolar approach may be more localized.
Due to a wider range of effect, the monopolar approach may cause unwanted skeletal muscle and/or nerve activation. In contrast, the bipolar approach has a constrained range of effect proportional to electrode spacing on the lead, and is less likely to depolarize cardiac myocytes or nerve fibers.
For the monopolar approach, only a single potential is applied in catheter wires and electrodes. Further, because all the electrodes are at the same polarity, the configuration is not susceptible to arcing (e.g., when using variable diameter loop 150). In contrast, for the bipolar approach, the internal architecture of the catheter must be constructed to prevent arcing, as different electrodes are at different potentials. Further, with a catheter having a variable diameter loop at the distal end (e.g., variable diameter loop 150), depending on the size of the loop and the orientation of the catheter, electrodes with opposite polarities may overlap, potentially resulting in arcing or shunted current paths, which is generally undesirable. Further, interleaved electrodes may interfere with signals used for tissue sensing.
To monitor operation of system 10, one or more impedances between catheter electrodes 144 and/or return electrodes 18, 20, and 21 may be measured. For example, for system 10, impedances may be measured as described in U.S. Patent Application Publication No. 2019/0117113, filed on Oct. 23, 2018, U.S. Patent Application Publication No. 2019/0183378, filed on Dec. 19, 2018, and U.S. Patent Application No. 63/027,660, filed on May 20, 2020, all of which are incorporated by reference herein in their entirety.
In the example embodiment, a plurality of wires (not shown in
Those of skill in the art will appreciate that handles 200 and 210 are merely examples, and that any suitable handles and/or arrangement of actuators may be used to implement the systems and methods described herein.
Within catheter 14, it is important to provide sufficient electrical isolation and dielectric strength resistance between positive and negative electrical wires (such as electrical wires 402 (shown in
For example, in embodiments where variable diameter loop 150 includes fourteen catheter electrodes 144, a total of fourteen corresponding electrical wires may be routed through variable diameter loop 150. These electrical wires carry relatively high voltage and current when energizing corresponding electrodes. Accordingly, positive and negative wires of the electrical wires should be sufficiently isolated from one another to avoid electrical breakdown or acing. Electrical arcing between two wires may, for example, cause burning or charring of material in catheter 14.
In some embodiments, to isolate various wires from one another, a multi-lumen arrangement is utilized. For example, variable diameter loop 150 is formed from a round tube shaped in a spiral shape. To facilitate operation of variable diameter loop 150, a shaping wire (e.g., a Nitinol wire), and activation wire, and electrical wires are routed thorough the tube. By pulling the activation wire, in some embodiment, variable diameter loop 150 can be straightened out into a linear shape (e.g., to facilitate inserting variable diameter loop 150 though an introducer).
Referring back to
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through first lumen 510, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through second lumen 512. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through third lumen 514. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may also be routed through third lumen 514.
When located within variable diameter loop 150, first and second lumens 510 and 512 are located opposite inner circumference 170, and proximate outer circumference 172. This configuration prevents electrical wires routed through first and second lumens 510 and 512 from stretching and breaking with variable diameter loop 150 is straightened out.
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through second lumen 612, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through third lumen 614. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through sixth lumen 620. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may be routed through fourth lumen 616. In this embodiment, first lumen 610 and fifth lumen 618 are dummy lumens that do not carry any wires. First and fifth lumens 610 and 618 do provide a structural benefit, however, as they keep wall thicknesses around second, third, fourth, and sixth lumens 612, 614, 616, and 620 relatively consistent.
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through first lumen 710, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through second lumen 712. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through fourth lumen 716. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may be routed through third lumen 714.
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through second lumen 812, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through third lumen 814. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through fifth lumen 818. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may also be routed through fifth lumen 818. In this embodiment, first lumen 810 and fourth lumen 816 are dummy lumens that do not carry any wires. First and fourth lumens 810 and 816 do provide a structural benefit, however, as they keep wall thicknesses around second, third, and fifth lumens 812, 814, and 818 relatively consistent.
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through first lumen 910, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through second lumen 912. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through third lumen 914. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may also be routed through third lumen 914.
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through first lumen 1010, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through second lumen 1012. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through third lumen 1014. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may also be routed through third lumen 1014.
In this embodiment, electrical wires having a first polarity (e.g., positive electrical wires) are routed through first lumen 1110, and electrical wires having a second polarity (e.g., negative electrical wires) are routed through second lumen 1112. Thus, electrical wires having different polarities are located in different lumens, electrically isolating them from one another. Further, in this embodiment, the shaping wire and activation wire are routed through third lumen 1114. Thus, the shaping and activation wires are separated from the electrical wires. Additional wires (e.g., a wire for magnetic sensor 302) may also be routed through third lumen 1114.
The multi-lumen embodiments described herein enable routing wires to help prevent electrical breakdown between electrical wires carrying high current and voltage. It also results in a more accurate and consist assembly process, reducing scraps and breaks in electrical wires. By routing different types of wires through different lumens, the chances of human error and device failure are reduced, and assembly time and costs are reduced as well.
Another technique for ensuring sufficient isolation is to use robust insulation on the electrical wires. Electrical wires in at least some known medical devices may have at most, for example, insulation having a thickness of approximately 0.0007 inches (0.01778 millimeters). However, in the systems and methods described herein, the insulation on electrical wires may have a thickness of, for example, up to approximately 0.0015 inches (0.0381 millimeters). This is roughly double the insulation of electrical wires in at least some known medical devices. The added thickness results in higher dielectric strength from the added material, and a substantially increased wire durability and strength to protect from abrasions, gouges, scratches, or other damage. This results in a consistent and reliable increase in the total dielectric strength of the electrical wires.
In other embodiments, physical separation of electrical wire pairs (to achieve added dielectric strength and isolation) may be achieved using various tubing arrangements. For example, a tubing made of a non-conductive or insulative material may be extended along the length of the wires throughout at least a portion of variable diameter loop 150 and/or shaft 44, providing physical separation and a barrier between electrical wire pairs as needed. The tubing may be, for example, fabricated from a heat shrink material such as polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), or other suitable materials. Alternatively, the tubing may be fabricated from fully expanded or extruded tubing without any shrinking capabilities. The material used for tubing may be selected, for example, based on space and/or fitting concerns for the quantity of electrical wires to be routed or the size of the catheter itself.
Pairs of tubing may be used to separate positive and negative wires. For example,
In some embodiments, to prevent electrical wires from dielectric breakdown, the amount of conductive fluid that the interior of catheter (e.g., the interior of variable diameter loop 150 and/or shaft 44) is exposed to is reduced. The conductive fluid may be, for example, saline or blood. To reduce the expose to conductive fluid, a sealant or filler material may be applied inside of the variable diameter loop 150 and/or shaft 44. The material may be, for example, silicone gel, urethane gel, or other suitable compliant and/or viscous materials. In one embodiment, the filler material is injected into a catheter section from a distal end of the catheter section, and an indicator hole (not shown) located at a proximal end of the catheter section facilitates determining when a complete fill is achieved.
Another technique for reducing the exposure to conductive fluid (and to prevent electrical wires from dielectric breakdown) is to eliminate, patch, seal, and/or reflow exposed holes in variable diameter loop 150 and/or shaft 44. These holes may be originally included, for example, to facilitate routing the various wires through variable diameter loop 150 and/or shaft 44. However, once the wires have been routed, these holes can be closed to reduce exposure to conductive fluid. In one embodiment, a suitable epoxy (e.g., urethane epoxy) is applied to each hole pierce. In another embodiment, RF energy is applied to catheter electrodes 144 in variable diameter loop 150. The application of RF energy causes thermoplastic material proximate catheter electrodes 144 to flow into and around holes in the vicinity. Applying the RF electrode material also has an additional benefit of embedding catheter electrodes 144 and corresponding wires more thoroughly within catheter 14, and sealing the edges of catheter electrodes 144 as well.
For example,
In this embodiment, wiring arrangement 2000 facilitates providing wiring for twelve ring electrodes. For clarity, only a twelfth electrode 2002, eleventh electrode 2004, tenth electrode 2006, and ninth electrode 2008 are shown. Further, in this embodiment, wires for even electrodes (e.g., including twelfth electrode 2002 and tenth electrode 2006) are routed through first lumen 1010, and wires for odd electrodes (e.g., including eleventh electrode 2004 and ninth electrode 2008) are routed through second lumen 1012.
In wiring arrangement 2000, the electrode wires for each electrode exit the associated lumen through a corresponding hole in tube 1002, and extend at least partially circumferentially around tube 1002 to a weld on the corresponding electrode.
For example, as shown in
In the embodiment shown in
Further, in this embodiment, electrode wires coming out of first lumen 1010 extend partially circumferentially in a first direction (e.g., clockwise), while electrode wires coming out of second lumen 1012 extend partially circumferentially in a second, opposite direction (e.g., counterclockwise). Alternatively, the electrode wires may all extend in the same direction, or may each extend in any suitable direction.
In addition, it should be noted that in
Extending electrode wires partially circumferentially around tube 1002 may provide benefits. For example, the ends of electrode wires typically each include an exposed conductor (e.g., bare copper). By extending the electrode wires as shown, any exposed conductor is located outside of first and second lumens 1010 and 1012. This prevents the exposed conductor from contacting fluids that may ingress into first and second lumens 1010 and 1012.
Those of skill in the art will appreciate that the various embodiments described herein for isolating wires from one another may be implemented independently from one another or in any suitable combination.
The embodiments described herein provide systems and methods for electroporation catheters. An electroporation catheter includes a shaft, and a variable diameter loop coupled to a distal end of the shaft, the variable diameter loop including a plurality of electrodes. The catheter further includes a plurality of electrical wires connected to the plurality of electrodes and extending through the variable diameter loop and the shaft, the plurality of electrical wires configured to energize the plurality of electrodes, and a multi-lumen arrangement extending through at least a portion of at least one of the shaft and the variable diameter loop. The multi-lumen arrangement includes a first lumen housing a first subset of the plurality of electrical wires, and a second lumen housing a second subset of the plurality of electrical wires.
Although certain embodiments of this disclosure have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this disclosure. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of the disclosure. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the disclosure as defined in the appended claims.
When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
This application claims priority to U.S. Provisional Application No. 63/210,098, filed on Jun. 14, 2021, the entire contents of which are hereby incorporated herein by reference. The present disclosure relates generally to tissue ablation systems. In particular, the present disclosure relates to isolating wires from one another in an electroporation catheter.
Filing Document | Filing Date | Country | Kind |
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PCT/US2022/033352 | 6/14/2022 | WO |
Number | Date | Country | |
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63210098 | Jun 2021 | US |