WO2021009648A1 - Cathéter d'ablation par champ pulsé - Google Patents

Cathéter d'ablation par champ pulsé Download PDF

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Publication number
WO2021009648A1
WO2021009648A1 PCT/IB2020/056538 IB2020056538W WO2021009648A1 WO 2021009648 A1 WO2021009648 A1 WO 2021009648A1 IB 2020056538 W IB2020056538 W IB 2020056538W WO 2021009648 A1 WO2021009648 A1 WO 2021009648A1
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Prior art keywords
electrode
catheter
ablation
electrodes
ablation catheter
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PCT/IB2020/056538
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English (en)
Inventor
Daniel Meckes
Benjamin King
Milanjot ASSI
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Cathrx Ltd
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Publication of WO2021009648A1 publication Critical patent/WO2021009648A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B18/1492—Probes or electrodes therefor having a flexible, catheter-like structure, e.g. for heart ablation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/1206—Generators therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00315—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for treatment of particular body parts
    • A61B2018/00345—Vascular system
    • A61B2018/00351—Heart
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00315—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for treatment of particular body parts
    • A61B2018/00345—Vascular system
    • A61B2018/00351—Heart
    • A61B2018/00357—Endocardium
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
    • A61B2018/00577—Ablation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
    • A61B2018/00613—Irreversible electroporation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/1206—Generators therefor
    • A61B2018/1246—Generators therefor characterised by the output polarity
    • A61B2018/126—Generators therefor characterised by the output polarity bipolar
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B2018/1467—Probes or electrodes therefor using more than two electrodes on a single probe
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M25/00—Catheters; Hollow probes
    • A61M25/0043—Catheters; Hollow probes characterised by structural features
    • A61M25/005—Catheters; Hollow probes characterised by structural features with embedded materials for reinforcement, e.g. wires, coils, braids

Definitions

  • the present invention relates to a catheter and, more particularly, to an ablation catheter.
  • an ablation catheter In the conduction of cardiac ablation procedures, an ablation catheter is used to ablate heart tissue to attempt to clear heart arrhythmias. Generally, a dot or spot ablation is made and this is repeated by re-positioning a tip also known as the ablation electrode of the ablation catheter. This is an extremely time-consuming process. In addition, dot or spot ablation may leave gaps in the lesions which may require additional re-positioning and repeating the procedure. If a clinician could form longer lesions, fewer manipulations would be required. This would reduce the time to conduct the procedure which would be beneficial for all concerned. Longer electrodes have been considered for radiofrequency ablation but coagulum tends to form on the electrodes. In addition, the larger electrodes may pick up far-field signals which makes ECG mapping very difficult. Furthermore, the temperature of the ablation electrodes as well as the tissue being treated needs to be carefully maintained to ensure that it does not result in excessive ablation or
  • Radiofrequency (RF) is a widely accepted energy source for myocardial ablation but may result in nontargeted tissue injury and stroke. Further, applying RF energy to atrial wall tissue can damage the oesophagus or nerves which are located in the region close to the heart. Due to a single-shot point ablation tip, RF ablation procedures may potentially require an extended period of treatment time to correct the arrythmia.
  • PFA pulsed field ablation
  • sub-second electric fields create microscopic pores in cell membranes - a process called electroporation 1 . Irreversible electroporation can be used as a nonthermal energy source to ablate tissue.
  • Cardiac catheter ablation by irreversible electroporation may be a safe and effective alternative for thennal ablation techniques such as radiofrequency or cryoablation.
  • Total applied current, not delivered power (watts), energy (joules), or voltage is the parameter that most directly relates to the local voltage gradient that causes electroporation.
  • Electroporation can be achieved with various modalities: direct current, alternating current, pulsed direct current, or any combination of these.
  • Experimental cardiac and noncardiac studies have demonstrated tissue specificity with survival of arteries and nerves in large lesions 2 .
  • porcine data suggest that application inside a pulmonary vein does not lead to pulmonary vein stenosis and that the oesophagus is remarkably insensitive to electroporation 3 .
  • Pulsed field ablation is a form of IRE (Irreversible Electroporation Ablation) that uses a train of bipolar and biphasic pulses of high voltage and short duration to create tissue injury without significant heating 4 .
  • IRE irreversible Electroporation Ablation
  • This research investigated using PFA delivery to a 9-electrode circular array catheter to achieve atrial myocardial injury comparable to that achieved by duty cycled RFA (Radiofrequency Ablation), with reduced injury to nontargeted tissues.
  • US2017/0035499A1 to Medtronic Inc. discloses a method for ablating tissue by applying at least one pulse train of pulsed-field energy.
  • the method includes delivering a pulse train of energy having a predetermined frequency to cardiac tissue.
  • the pulse train of energy includes a plurality of Voltage amplitudes, at least 60 pulses, an inter-phase delay between Ous and 5us, an inter-pulse delay of at least 400 us, a pulse width of 1-15 us, and a voltage between 300V and 4000V.
  • the plurality of Voltage amplitudes includes a second amplitude being higher than a first amplitude, wherein the biphasic pulses delivered at the first amplitude are delivered at a higher frequency than the biphasic pulses delivered at the second amplitude.
  • the pulses may be short (e.g. nanosecond, microsecond, or millisecond pulse width) order to allow application of high voltage, high current (example, 5 or more amps) without long duration of electrical current flow that results in significant tissue heating and muscle stimulation.
  • high voltage, high current example, 5 or more amps
  • such methods require specialised catheter designs at a high manufacturing cost and not flexible in application during a surgical procedure.
  • a first aspect of the present invention may relate to an ablation catheter comprising: a control handle having an electrical connector arranged at a proximal end of the control handle, the electrical connector being connectable to an electrical energy source; a catheter sheath having a proximal end and a distal end, the catheter sheath defining an outer sheath and an inner lumen wherein the lumen comprises a catheter shaft the catheter sheath being connectable to the control handle; a first electrode pair and a second electrode pair, wherein each electrode pair comprises a first electrode and a second electrode to create an electric field, wherein spacing between the first and second electrode, and spacing between the first electrode pair and the second electrode pair along the catheter shaft is calculated based on the electric field required to produce a
  • the electrical field is defined as: where is the electrical field; k is the proportionality constant (3.53 10 5 Nm 2 C 2 ); a is 1 ⁇ 2 the distance between electrodes; and y is the electric field penetration depth, which corresponds to a therapeutic lesion depth.
  • the first electrode and second electrode may deliver bipolar biphasic pulses such that linear and spot ablation lesions can be performed using a single catheter.
  • the fust electrode is located at the catheter tip.
  • the first electrode and second electrode may be connected through a single channel electrical system, such that the bipolar biphasic pulses can only travel between the electrode tip and second electrode.
  • the second electrode and a third electrode are connected through a single channel system, such that the bipolar biphasic pulses can only travel between the second electrode and third electrode.
  • the second electrode may change between channels acting as either an electrode pair with the first electrode tip or an electrode pair with the third electrode.
  • the electrode pair may include the First electrode at the catheter tip is for single point spot ablation and the electrode pair with the third electrode is for a linear lesion ablation.
  • a plurality of electrodes is arranged in pairs, commencing with the second and third electrode, such that each pair are electrically isolated one from another to produce a uniform lesion across different tissue resistivities.
  • the plurality of electr odes also functions in a single channel format and shares electrical signals throughout the plurality electrodes.
  • the first electrode at the catheter tip and the second electrode such that the system is a single channel system used only for single shot spot ablation.
  • the spacing between the spacing between the electrode pairs along the longitudinal axis of the catheter is preferably from about 2mm to about 4mm.
  • the spacing between the first electrode and a second electrode in an electrode pair ⁇ may be about 0.1mm to 1mm.
  • the electrodes may be formed from an inert metal such as platinum, iridium or gold.
  • the electrodes of the invention may be about 2mm in length, and about 0.1 to 0.3mm thickness.
  • the catheter can produce electric fields causing reversible and irreversible electroporation of cells.
  • the preferred threshold of irreversible electric field strength is between about 200 V/cm and 500 V/cm.
  • a particularly preferred thr eshold of electric field strength for the pulse field ablation catheter of the invention is between about 260 and 420 V/cm.
  • a voltage of greater than 500V may be delivered to one of the electrodes within the electrode pair.
  • the remaining electrode in each pair then acts as a ground source.
  • the voltage may then pass from the first electrode and into the second electrode, such that an electric field is created between the paired electrodes.
  • the plur ality of electrodes preferably spans a length of about 20 to 50mm to interface with the targeted tissue areas in need of therapy and wherein the plur ality of electrodes preferably includes approximately 3 to 8 paired electrodes, or approximately 4 to 10 paired electrodes.
  • each electrode pair includes a single channel pulse delivery system.
  • the system may comprise 1 to 6 single channels such that such that each electrode pair each have an individual channel and the secondary electrode shares either a channel with the first electrode at the catheter tip or the third electrode.
  • the second electrode can jump from the first channel driver to the second channel driver during tire same application.
  • the electrode pairs may be energized separately in their own respective channels, wherein the applied voltage is about 900-4000V, and each separate channel ensures equal voltage delivery despite unequal tissue resistivity and applied current. The separate channel ensures one electrode pair is not starved due to voltage and current sharing.
  • the catheter of the invention comprises a stainless- steel fibre for improved torque transmission from the handle to catheter tip, wherein the proximal catheter shaft comprises stainless steel fibre or a metal braid and the distal electrode carrying portion of the catheter has no electrically conductive components inside the catheter sheath.
  • This feature reduces the potential for the high voltage electrodes to energize the metal braid causing undue electrical injury to end users without compromising catheter mechanical performance.
  • the flexural rigidity of the materials comprising the catheter shaft may be such that the catheter can be formed into a linear and a loop catheter, creating linear and circular lesions in a single application, and improved tissue contact for linear and spot ablation procedures
  • the catheter may be used on a modular platform from which catheter handles and steering mechanisms can be reprocessed and reused to reduce procedural costs.
  • the catheter may also be used on a modular platform such that difference curve sizes and loop configurations can be applied during a single application, wherein the steering and shape imparting mechanisms are electrically insulated from the high voltage carrying wires.
  • the distal portion of the catheter sheath comprises a braided tube formed from elastomeric polymer and polymer drawn fibre comprising a braid angle in the range 20° and 70° to maintain flexural rigidity and buckling loads requirements in both the linear and loop configurations.
  • the inner lumen in the distal portion of the catheter sheath comprises a steering and shape imparting mechanism that is electrically insulated from high voltage carrying wires and wherein the inner lumen physically separates the steering and shape imparting mechanism from high voltage wires.
  • the ablation catheter may be used from a modular platform from a steerable nitinol stylet or a fixed mandrel.
  • the flexural rigidity of materials comprising the catheter shaft are tuned for improved lateral stiffness and torque-ability for improved catheter tissue contact for linear and spot ablation procedures.
  • the catheter of the present invention may be for use in intracardiac pulsed-field ablation.
  • the present invention provides a catheter for treating atrial fibrillation that is modular in design and delivers minimally non-thermal pulsed field ablation energy to the heart that creates cardiac lesions of non-conduction (the primary end-point of AF
  • This catheter design comprises of an array of therapeutic electrodes that can support any catheter curve size.
  • the catheter can be formed from a linear configuration and into a deflectable variable loop configuration to reduce manufacturing and subsequent medical procedure costs.
  • the preferred catheter design is such that the linear catheter has an electrode spacing such that linear and spot ablation lesions can be performed using a single catheter. This is made possible through a bipolar biphasic dual electrode tip. With these modular designs, physicians can reduce the number of sheaths needed for both linear and circular lesions during the same procedure reducing the overall cost of the consumables used.
  • the composite tube of the catheter sheath is designed to minimize access site injury and maximize electric field distribution. Flexural rigidity of the composite tube is tuned to maintain peak compressive force requirements to reduce the risk of cardiac perforation.
  • the invention is to be interpreted with reference to the at least one of the technical problems described or affiliated with the background art.
  • the present aims to solve or ameliorate at least one of the technical problems and this may result in one or more advantageous effects as defined by this specification and described in detail with reference to the preferred embodiments of the present invention.
  • Figure 1 depicts perspective views of two irreversible electroporation (IRE) catheters according to the present invention whose array of therapeutic electrodes can support any curve size as well as a variable loop configuration.
  • IRE irreversible electroporation
  • Figure 2 depicts a perspective view of the catheter sheath of the present invention illustrating the proximal outer jacket and electrically insulative braid.
  • Figure 3 depicts a side and end view of a preferred embodiment of the catheter sheath including the electrically insulative lumen running parallel to high voltage carrying wires.
  • Figure 4 depicts a side view of a preferred embodiment of the electrodes on the catheter of the present invention.
  • Figure 5 depicts a simplified geometric model of application of the catheter of the present invention to heart tissue.
  • Figure 6 depicts a graphical representation of analytical, computational, and porcine experimental results (n 8) of lesion depth. Electrodes are spaced 4 mm apart Load restraints are: an electric charge of 7.35 ⁇ 10-7 C for the analytical model; a fixed voltage of 500 and OV for the computational model; and the in-vivo voltage loads match computational restraints, and both have an assumed irreversible electroporation threshold of 268 V/cm.
  • Figure 7 depicts an electrostatic FEA electric field plot of two electrodes, spaced in ser ies, at a 4 mm interval. Centre: two electrodes in series attached to a non-conductive tube. Top: electric field penetration into blood. Bottom: electric field penetration or lesion depth into heart muscle.
  • Figure 8 depicts tip and side views of electrodes of the catheter of the present invention.
  • Figure 9 depicts a perspective view of a handle of the catheter of the present invention.
  • Figure 10 depicts a top view of the catheter of the present invention.
  • Figure 11 depicts a top and side view of an electrode tip of a first electrode in a catheter of the present invention.
  • the electrophysiology catheter 1 of the present invention is developed around a proprietary modular platform 2 from a steerable nitinol stylet or fixed mandrel.
  • This modular platform 2 of the present invention allows end users to reprocess the handle 3 and steering mechanism 4 for reuse, which significantly reduces procedural costs, and allows doctors to perform advanced IRE lesions of differing geometries.
  • the overall design leverages mechanical characteristics for optimal control and anatomical positioning for superior electrode-tissue contact and improved PFA dose delivery.
  • the catheter shaft 6 is therefore stripped of all potential conductors.
  • the distal shaft 6 is preferably comprised of an elastomeric polymer braided tube 7, including Kevlar polymer drawn fibre 8.
  • a polymer composite tube 7 contains the modular platform 2 while an additional internal lumen 11 insulates the nitinol steering mechanism 4 from the charged wires 9. This combination gives a flexural rigidity needed for the desired mechanical characteristics and additional functionality.
  • the LCP drawn fibre has dimensions of around 0.1 ⁇ 0.025 x 0.05 ⁇ 0.025 and a cross-sectional area of 5.2e-3 mm 2 to maintain flexural rigidity and buckling loads requirements in both the linear and loop configurations.
  • the braid angle is preferably in the range of 20° to 60°, preferably in the range of 30° to 50°, more preferably between about 35° and 45°, most preferably 41°.
  • the Kevlar wires are preferably configured in a 16- wire herringbone (1 wire over 2, under 2) braid pattern, which is shown in Figure 2.
  • Each of the 16 Kevlar wires is preferably of about 0.1mm x 0.05mm (thickness) rectangular cross-section, which equates to about a cross-sectional area of 5.2x10 -3 mm 2 per wire.
  • This cross-section combined with a braid angle tuned to between 20° to 60°, most preferably ⁇ 41°delivers desirable torque transmission and flexural stiffness tuned for both linear and loop configurations.
  • the approximate 0.05mm individual wire thickness yields an overall braid thickness of about 0.102mm, allowing the braiding to fit geometrically within the catheter shaft wall.
  • the distal sheath 7 is comprised of a polymer or Kevlar fibres which is thermally joined to the proximal sheath 6 containing stainless steel metal fibres for improved torque transmission.
  • This configuration limits electrically conductive materials in the distal sheath, which may potentially meet dhe high voltage delivering electrodes 5.
  • the polymer matrix material contained in the composite or braided tube may include a mixture of materials to increase or decrease the flexural rigidity of the sheath such that a high lateral stiffness and torque transmission is achieved for superior tissue-electrode contact and improved PFA dose delivery.
  • the improved lateral and torque transmission further supports the catheter drive-ability such that linear and spot ablation lesion can be performed using a single sheath during a single procedure.
  • a thermoplastic outer jacket 10, formed from PET, on the shaft 6 may transmit direct 1:1 motion transfer without significantly adding to the profile of the device, because of the ultrathin walls.
  • the PET outer jacket is also an effective electrical insulation material.
  • a proximal shaft 6 may be comprised of a polymer matrix material and stainless steel such that the torque is comparable if not better than the PET outer jacket without compromising electrical safety as the conductive metallic braid does not come in contact with the high voltage electrodes 5.
  • the catheter sheath may define a braided outer sheath and an internal insulative lumen wherein the insulative lumen separates a shape imparting mechanism from a set of high voltage charged wires.
  • Myocardial irreversible electroporation requires high voltages (i.e. >500V).
  • the composite tube 7 on the catheter shaft 6 was stripped of all potential conductors to reduce tire risk of arcing or electromagnetic interference between conduction paths 7 .
  • a polymer drawn fibre 8 was used to improve lateral stabilization, bending motion, and torque transfer. Consequently, an ultrathin outer jacket 10 was added to the proximal shaft 12, as torsional rigidity was impaired when compared to metal drawn fibre. This additional sleeve 10 transmits approximately 1 : 1 motion transfer without significantly adding to the profile of the device—which may otherwise be an important factor contributing to access site complications.
  • proximal shaft 12 may also be comprised of a metal braid fibre to improve torque transmission greater than the PET outer jacket 10.
  • the catheter was designed such that the distal shaft 13 must buckle at a peak compressive load of approximately less than ⁇ 3.5 N at the tip-tissue interface.
  • catheter buckling can be treated as a column and a similar Euler’s equation (Equation 3) applies:
  • P cr is the critical or peak compressive load
  • El is the flexural rigidity
  • Flexural and torsional rigidities are illustrated graphically in Figure 4.
  • Data acquisition is gathered using validated in-house test rigs and solved for using equations (1) & (2). Specimens were tested at the most distal (50 mm) portion of the catheter shaft 6 containing the linear array of electrodes 5.
  • flexural rigidity a value of 3.6 ⁇ 10 -4 Nm 2 was obtained.
  • torsional rigidity a value of 1.47 ⁇ 10 4 Nm 2 was also obtained.
  • Buckling test results include a peak compressive load of 2.2 N.
  • flexural rigidity is 3.60 ⁇ 10 -4 and 2.73 ⁇ 10 -4 Nm 2 measured in the flexural and buckling tests, respectively.
  • a preferred embodiment of the electrodes 5 of the present invention are made of pure gold and are preferably about 2 mm in length with a thickness of about 0.1-0.2mm.
  • Wires are preferably copper 35AWG; with heavy polyimide insulation, having a preferred minimum dialectic strength of about 1500V. Tips are designed with similar specifications but preferably maintain a 4 mm length.
  • the distal tip is electrically active and operates in a similar fashion to the electrodes.
  • the tip also preferably has a similar shape and size, preferably 2mm in length, as the electrodes.
  • one electrode design of the present invention is a 2mm tip having similar shape and size as the ring electrode, wherein the spacing between tip and electrode pair is less than 1mm. This feature gives the impression of a 4mm when the tip is otherwise split into two 2mm electrodes that function as pair to deliver bipolar biphasic signals between the two adjacent electrodes.
  • a further embodiment wherein the 2mm ring electrode included in the 4mm tip assembly can also function as pair with the 3 rd electrode and deliver bipolar biphasic pulsed fields during linear ablation.
  • This function means the second electrode within the tip-electrode assembly functions as an alternating pair for either the distal tip or as the distal electrode for spot ablation.
  • the electrode tip 20 on the first electrode 21 and the second electrode 22 may deliver bipolar biphasic pulses having voltages less than 3000V, pulse widths less than 100ms, and interpulse delays less than 100ms, in pulse trains of approximately 50 to 1000 pulses.
  • the electrode tip of the first electrode is illustrated in Figures 8 and 11 wherein the electrode tip can pair with the second electrode for single point spot ablation.
  • the second electrode 22 and third electrode 23 (also shown in Figures 8 and 11) can be paired for a linear lesion ablation.
  • the handle and steering mechanism are illustrated in Figures 9 and 10 depicting the modular platform of the present invention that allows end users to reprocess the handle 3 and steering mechanism 4 for reuse.
  • the electrode 5 geometry and spacing 14 on the catheter 1 could be used to determine the electric field and subsequently the lesion size and depth resulting from application of the catheter.
  • FEA Electrostatic Finite Element Analysis
  • a simplified analytical model can be used such as an electrical dipole between two-point charges. According to Coulomb’s law, the electrical field is therefore defined as:
  • Lesion length was measured in the simulated models; however, these could not be compared to ⁇ h-vivo results as the lesions were created using a curved catheter configuration.
  • the decreased lesion width outlined in Table 1 may be due to fundamental differences between simulation and in-vivo experimentation.
  • electrostatics FEA simulates an electric field, created in a static environment, by a single pulse.
  • the in-vivo results are based on a series of alternating pulses over 20 ms.10
  • the increased width observed in-vivo may be due to catheter displacement and multi-shot pulses in relation to the pulsating cardiac rhythm. In other words, a larger treatment area was achieved due to heart movement in conjunction with multiple pulsed ablations.
  • the ti-ue in-vivo heart muscle may be an orthotropic material in which the conductivity of heart muscle incr eases depending on the direction in which it is measured. This would mean that the heart muscle is more conductive in the plane that lies parallel to the catheter and remains less conductive along the plane that runs perpendicular to the catheter’s shaft.
  • Electrode spacing 14 appears to have a significant effect on electric fields. It was found that 3 and 4 mm spacing produced comparable lesion depths. A 4 mm spacing produces a greater lesion length due to the increased (4 mm) intervals and is therefore the preferred electrode spacing choice as a larger lesion is achieved. Surprisingly, increased electrode spacing 14 greater than 4 mm was found to result in depreciating non-uniform lesion depths. Finally, there was found to be no correlation between electrode thickness and lesion size. This is illustrated in Figure 8, which depicts electrostatic FEA electric field plot comparison of two electrodes, spaced 4 mm apart Electrodes have an overall thickness of 0.05 mm (0.002”). No significant change in lesion depth was observed in comparison to a second electrode having an electrode thickness of 0.127 mm (0.005”).
  • Electrode spacing less than 3mm also demonstrated little effect on electric field depth. Naturally, the electric field length decreased as the spacing decreased. This means that the distal tip and distal ring electrode may be spaced relatively close together ( ⁇ lmm) without any change in lesion depth, therefore acting as an effective 4mm tip with combined tip and ring electrode for bipolar biphasic delivery of pulsed electric fields.
  • the high torque transmission of the present invention may not compromise the overall profile of the catheter, which can allow the design to be compatible with standard clinical-care vascular access methods, which may benefit access site complications over larger therapeutic devices.
  • the low flexural rigidity of the catheter of the present invention may permit for both linear and loop configurations of the catheter to allow physicians to perform linear ablation and pulmonary vein isolation with one device, unlike other‘single-shot’ technologies that can do either pulmonary vein isolation or linear' ablation.
  • the flexural rigidity maintains a peak compressive force below the known cardiac perforation force that can allow the catheter to maintain a high safety profile.
  • an electric charge of 7.35 ⁇ 10 -7 C was estimated based on a known lesion depth of 2.25 ⁇ 0.85 mm as well as a permanent electric field threshold of 268 V/cm. Once the charge was established, the field depth was varied, and the resulting electric field recorded.
  • the threshold of irreversible electric field strength was selected by the present inventors to be 268 V/cm. This value is lower than that proposed by others who describe the requirement for 400 V/cm for irreversible electroporation to occur 11 .
  • an expected lesion depth of 1.52 mm would be the outcome having a 500V load.
  • An overall decreased lesion size is typically expected due to an increased permanent electroporation threshold e.g. 268 vs 400 V/cm. Nevertheless, this smaller lesion depth does fall within the lower limit standard deviation of experimental results.
  • the FEA model presented herein is used to evaluate the effects of load restraints, electrode spacing, and electrode thickness and the resultant electric field generated between two electrodes.
  • the observations of the present inventors lead towards an unexpected optimum electrode spacing of about 4 mm due to the deep uniform electric field (i.e. lesion) produced as well as the increased lesion length in comparison to about 3 mm spacing.
  • electrode thickness does not affect lesion size, which may also open opportunities for changes (such as using a less precious metal) to further reducing the overall cost of the final device.
  • the analytical and computational results obtained indicate that the catheter of the present invention has potential to offer high performance and unique features to maintain the highest levels of procedural safety and efficacy, yet on a platform that can be manufactured at scale, economically.

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Abstract

L'invention concerne un cathéter d'ablation comprenant une poignée de commande reliée à une gaine de cathéter, délimitant une gaine extérieure et une tige de cathéter à lumière intérieure ; une première paire d'électrodes et une seconde paire d'électrodes, chaque paire d'électrodes comprenant une première électrode et une seconde électrode pour créer un champ électrique, l'espacement entre les première et seconde électrodes, et l'espacement entre la première paire d'électrodes et la seconde paire d'électrodes le long de la tige de cathéter, étant calculés sur la base du champ électrique requis pour produire une taille et une profondeur de lésion prédéterminées résultant de l'application du cathéter, le champ électrique étant défini comme suit : E = 2kqa/(a 2 + y 2 ) 3/2 I, E étant le champ électrique ; k étant la constante de proportionnalité (3,53 ×105 Nm2C2) ; a étant ½ de la distance entre les électrodes ; et y étant la profondeur de pénétration du champ électrique, laquelle correspond à une profondeur de lésion thérapeutique.
PCT/IB2020/056538 2019-07-16 2020-07-13 Cathéter d'ablation par champ pulsé WO2021009648A1 (fr)

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CN113967065A (zh) * 2021-06-23 2022-01-25 四川锦江电子科技有限公司 一种能够进入组织内部的脉冲电场消融导管
CN114469308A (zh) * 2021-12-23 2022-05-13 心航路医学科技(广州)有限公司 一种脉冲电场消融系统
WO2022251447A1 (fr) * 2021-05-28 2022-12-01 Boston Scientific Scimed Inc Cathéter d'ablation à champ pulsé ponctuel
WO2023026106A1 (fr) * 2021-08-25 2023-03-02 Cathrx Ltd Cathéter d'ablation à champ pulsé à électrodes multiples pour la création de lésions ponctuelles
WO2023142567A1 (fr) * 2022-01-27 2023-08-03 四川锦江电子医疗器械科技股份有限公司 Cathéter d'ablation

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* Cited by examiner, † Cited by third party
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WO2022251447A1 (fr) * 2021-05-28 2022-12-01 Boston Scientific Scimed Inc Cathéter d'ablation à champ pulsé ponctuel
CN113967065A (zh) * 2021-06-23 2022-01-25 四川锦江电子科技有限公司 一种能够进入组织内部的脉冲电场消融导管
CN113967065B (zh) * 2021-06-23 2023-08-11 四川锦江电子医疗器械科技股份有限公司 一种能够进入组织内部的脉冲电场消融导管
WO2023026106A1 (fr) * 2021-08-25 2023-03-02 Cathrx Ltd Cathéter d'ablation à champ pulsé à électrodes multiples pour la création de lésions ponctuelles
CN114469308A (zh) * 2021-12-23 2022-05-13 心航路医学科技(广州)有限公司 一种脉冲电场消融系统
WO2023142567A1 (fr) * 2022-01-27 2023-08-03 四川锦江电子医疗器械科技股份有限公司 Cathéter d'ablation

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