WO2024012822A1 - Electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment - Google Patents

Electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment Download PDF

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Publication number
WO2024012822A1
WO2024012822A1 PCT/EP2023/066742 EP2023066742W WO2024012822A1 WO 2024012822 A1 WO2024012822 A1 WO 2024012822A1 EP 2023066742 W EP2023066742 W EP 2023066742W WO 2024012822 A1 WO2024012822 A1 WO 2024012822A1
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WO
WIPO (PCT)
Prior art keywords
instrument
end portion
diameter
electrosurgical instrument
instrument tip
Prior art date
Application number
PCT/EP2023/066742
Other languages
French (fr)
Inventor
Malcolm White
Christopher Hancock
Patrick BURN
Original Assignee
Creo Medical Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Creo Medical Limited filed Critical Creo Medical Limited
Publication of WO2024012822A1 publication Critical patent/WO2024012822A1/en

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Classifications

    • 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
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
    • 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
    • A61B2018/00541—Lung or bronchi
    • 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
    • A61B2018/00589—Coagulation
    • 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
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
    • A61B2018/183—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves characterised by the type of antenna
    • A61B2018/1853—Monopole antennas
    • 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
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
    • A61B2018/1861—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves with an instrument inserted into a body lumen or cavity, e.g. a catheter

Definitions

  • Electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment
  • the invention relates to an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , wherein the electrosurgical instrument comprises a coaxial feed cable and an instrument tip .
  • the coaxial feed cable includes an inner conductor having a first maximal outer diameter, an outer conductor coaxial with the inner conductor , and a dielectric material separating the outer conductor and the inner conductor .
  • the coaxial feed cable is configured to convey the microwave electromagnetic energy and having a second maximal outer diameter .
  • the instrument tip is configured to emit the microwave electromagnetic energy .
  • the invention further relates to an electrosurgical apparatus comprising a generator and the electrosurgical instrument .
  • a diameter of bronchial tubes decreases the more the bronchial tube is away from the trachea . This means that a diameter of the endoscope needs to be small in order to reach end sections of bronchial tubes .
  • a small diameter of the endoscope provides technical limitations for conveying electromagnetic energy for tissue treatment as well as for a radiating structure for emitting electromagnetic energy . For example , generally, the attenuation of a coaxial cable increases with the reduction of its diameter . Further, the attenuation of a coaxial cable increases with an increase in the frequency of the electromagnetic energy conveyed by the coaxial cable .
  • the obj ective of the invention is to provide an electrosurgical instrument for conveying and emitting microwave electromagnetic energy having a small diameter so that the electrosurgical instrument is configured for endoscopic lung treatment .
  • the present invention provides an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , wherein the electrosurgical instrument includes a coaxial feed cable and an instrument tip for emitting electromagnetic energy conveyed by the coaxial feed cable , and wherein the instrument tip is configured to emit electromagnetic energy in a microwave frequency range while both the coaxial feed cable and the instrument tip have a small diameter .
  • an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , comprising a coaxial feed cable and an instrument tip .
  • the coaxial feed cable includes an inner conductor having a first maximal outer diameter, an outer conductor coaxial with the inner conductor , and a dielectric material separating the outer conductor and the inner conductor, the coaxial feed cable being for conveying the microwave electromagnetic energy and having a second maximal outer diameter .
  • the instrument tip is made from an electrically conductive material and is configured to emit the microwave electromagnetic energy, e . g . , into the biological tissue .
  • the instrument tip is electrically connected to the inner conductor and is electrically insulated from the outer conductor .
  • the instrument tip includes a distal end portion and a proximal end portion that is closer to the coaxial feed cable than the distal end portion .
  • the proximal end portion has a third minimal outer diameter and a fourth maximal outer diameter , wherein the third diameter is larger than the first diameter .
  • an electrosurgical apparatus for tissue treatment comprising the electrosurgical instrument and a generator optionally configured to generate microwave electromagnetic energy having a frequency between 433 MHz and 5 . 8 GHz .
  • the electrosurgical instrument can be used for coagulating and/or ablating biological tissue , such as lung tissue , by the emission of microwave electromagnetic energy into the biological tissue .
  • the electrosurgical instrument in particular a proximal end of the coaxial feed cable , may be connected to the generator that generates the microwave electromagnetic energy .
  • the electrosurgical instrument may be any instrument , or tool , which is used during surgery and which utilises microwave frequency energy .
  • microwave radiation may mean electromagnetic radiation having a stable fixed frequency in the range between 300 MHz to 100 GHz .
  • Optional spot frequencies for the microwave energy include 433 MHz , 915 MHz , 2 . 45 GHz , and 5 . 8 GHz .
  • the generator may be configured to generate one or more of these spot frequencies .
  • the electrosurgical instrument may be an endoscopic instrument , i . e . an instrument that can be inserted into a cavity of a body for treating tissue close to or in the cavity of the body .
  • the electrosurgical instrument is configured to treat tissue at , within, or close to the cavity of the body such as a bronchial tube .
  • the electrosurgical instrument may be suitable for use with an endoscope or another type of scoping device ( e . g . a bronchoscope ) .
  • the electrosurgical instrument may be inserted into a catheter .
  • a first or proximal end of the coaxial feed cable is for connecting the cable to the generator for supplying the microwave frequency energy to the cable .
  • the first end of the coaxial feed cable may have a terminal or connector for connecting the first or proximal end of the cable to the generator .
  • the coaxial feed cable may be for conveying microwave frequency energy from a generator connected to the first (proximal ) end of the cable assembly to the instrument tip which is permanently connected ( e . g . directly or indirectly) to a second ( distal ) end of the coaxial feed cable .
  • the inner conductor and the outer conductor are coaxially arranged in order to form a coaxial cable capable of transmitting microwave energy .
  • the outer conductor may completely or partially surround the inner conductor .
  • an angular degree of extension of the inner conductor along a circumferential direction corresponds to an angular degree of extension of the outer conductor along the circumferential direction . That is , the inner conductor may be radially aligned with, or may radially overlap with, the outer conductor .
  • the inner conductor and the outer conductor may not form a complete circle in a cross- sectional view of the coaxial cable .
  • the inner conductor and/or the outer conductor extend only to 3/ 4 , 4 /5 , or other ratios of the complete circumference of the coaxial layer .
  • the inner conductor, the dielectric material , and/or the outer conductor have a ring shape in a cross- sectional view of the coaxial feed cable .
  • the inner conductor, the dielectric material , and/or the outer conductor have a circular shape in the cross-sectional view of the coaxial feed cable .
  • the inner conductor can be a solid body that extends along an axial direction of the coaxial feed cable .
  • the inner conductor and/or the outer conductor are made from an electrically conductive material , such as metal .
  • the inner conductor and/or the outer conductor can be made from copper , aluminium, and/or tin .
  • the dielectric material is provided for electrically insulating the inner conductor from the outer conductor .
  • the dielectric material may be made from an electrically insulating material .
  • the dielectric material and/or the outer conductor may have a ring shape in a cross-sectional view of the coaxial feed cable , in particular a circular shape .
  • the inner conductor, the outer conductor , and/or dielectric material can be coaxially arranged to each other .
  • the coaxial feed cable in particular the outer conductor, may be covered or wrapped in a cover layer which is provided for mechanical strength, proofing ( e . g . protecting ) against entry of chemicals , such as water, and/or shielding the coaxial cable from mechanical damage .
  • the cover layer may be made from a plastic material and can be electrically insulating .
  • the inner conductor, the dielectric material , the outer conductor, and/or the cover layer can continuously extend from the distal end to the proximal end of the coaxial feed cable .
  • the instrument tip may be permanently attached ( e . g . directly or indirectly) to the inner conductor at the distal end of the coaxial feed cable .
  • the instrument tip is provided for emitting the electromagnetic energy that is conveyed by the coaxial feed cable from the generator .
  • the instrument tip can be considered a monopole antenna .
  • the instrument tip is electrically insulated from the outer conductor, for example by the dielectric material.
  • the instrument tip is made from electrically conductive material such as stainless steel which may be gold plated.
  • the instrument tip is entirely made from electrically conductive material.
  • the instrument tip solely consists of electrically conductive material.
  • the instrument tip is configured to emit electromagnetic energy as microwave radiation, optionally over a frequency range such as between 433 MHz and 5.8 GHz.
  • the instrument tip may be configured to emit microwave radiation at spot frequencies such as 433 MHz, 915 MHz, 2.45 GHz, and 5.8 GHz.
  • the configuration of the instrument tip to emit radiation at certain frequency means that the transmission efficiency is sufficiently high for tissue treatment, i.e. the emitted electromagnetic radiation in the frequency range or at the spot frequencies has an intensity sufficient for tissue treatment (e.g. ablation and/or coagulation) .
  • the back reflection at the instrument tip in the frequency range or at the spot frequencies is sufficiently low.
  • the instrument tip may consist of the proximal end portion and the distal end portion, i.e. the proximal end portion and a distal end portion make up the complete instrument tip.
  • the proximal end portion and the distal end portion may differ in their outer shape. In this case, the distal end portion and the proximal end portion can be visibly distinguished. However, the proximal end portion and the distal end portion may have the same outer shape. In this case, the distal end portion and the proximal end portion cannot be visibly distinguished.
  • the proximal end portion and a distal end portion may be a unitary component.
  • the first outer diameter refers to a maximum distance - in a cross-sectional view - between two opposing points on an outer surface of the inner conductor.
  • the first outer diameter refers to the distance between that pair of opposing points on the outer surface of the inner conductor in a cross-sectional view which is the largest among the plurality of distances corresponding to any pairs of opposing points on the outer surface of the inner conductor .
  • the first outer diameter corresponds to the mathematical definition of a diameter if the inner conductor has a circular outer surface in a cross-sectional view .
  • the second outer diameter refers to a maximum distance - in a cross-sectional view - between two opposing points on an outer surface of the coaxial feed cable .
  • the second outer diameter refers to the distance between that pair of opposing points on the outer surface of the coaxial feed cable in a cross-sectional view which is the largest among the plurality of distances corresponding to any pairs of opposing points on the outer surface of the outer conductor .
  • the second outer diameter corresponds to the mathematical definition of a diameter if the coaxial feed cable has a circular outer surface in a cross-sectional view .
  • fourth outer diameter refers to a maximum distance - in a cross-sectional view - between two opposing points on an outer surface of the proximal end portion .
  • the fourth outer diameter refers to the distance between that pair of opposing points on the outer surface of the proximal end portion in a cross-sectional view which is the largest among the plurality of distances corresponding to any pairs of opposing points on the outer surface of the proximal end portion .
  • the fourth outer diameter corresponds to the mathematical definition of a diameter if the proximal end portion has a circular outer surface in a cross-sectional view .
  • the third outer diameter refers to the minimal distance - in a cross-sectional view - between two opposing points on an outer surface of the proximal end portion .
  • the third outer diameter corresponds to the mathematical definition of a diameter if the proximal end portion has a circular outer surface in a cross-sectional view .
  • the proximal end portion may have a shape having a varying diameter along its direction of extension .
  • the proximal end portion has a minimal third outer diameter and a maximal fourth outer diameter .
  • the minimal third outer diameter is larger than the first maximal outer diameter of the inner conductor .
  • a volume defined by the proximal end portion is greater than a volume of a section of the inner conductor having the same length as the proximal end portion .
  • the outer surface area of the proximal end portion or the instrument tip can be increased with regard to the outer surface area of the inner conductor having the same length as the proximal end portion .
  • the inventors have surprisingly discovered that the characteristics of the instrument tip improve with the volume defined by the instrument tip .
  • the ratio of emitted electromagnetic radiation in relation to the electromagnetic energy conveyed by the coaxial feed cable increases with the volume defined the instrument tip .
  • the size of the frequency range of the electromagnetic radiation that can be emitted by the instrument tip increases with the volume defined by the instrument tip . This means that the instrument tip has better emission characteristics compared to a radiating structure that is constituted by only the inner conductor .
  • the fourth diameter is smaller than or equal to the second diameter .
  • the second diameter may be constituted by the outer conductor or the cover layer arranged on the outer conductor .
  • the second diameter defines a diameter of an opening into which the electrosurgical instrument can be inserted .
  • the fourth diameter is smaller than or equal to the second diameter so that the proximal end does not radially protrude beyond the coaxial feed cable . This means that the proximal end portion and the coaxial feed cable can be inserted into the same opening .
  • the distal end portion may also have a maximum outer diameter which is smaller or equal to the second diameter .
  • the instrument tip and the coaxial feed cable can be inserted into the same opening .
  • the inner conductor may have a fifth outer diameter that is perpendicular to the first maximal outer diameter .
  • the coaxial feed cable has a sixth outer diameter that is perpendicular to the second maximal outer diameter .
  • the proximal end portion has a seventh outer diameter that is perpendicular to third minimal outer diameter and an eighth outer diameter that is perpendicular to the fourth maximal outer diameter .
  • the seventh diameter optionally is larger than the fifth diameter and the eighth diameter optionally is smaller than or equal to the sixth diameter .
  • the proximal end portion is also thicker than the inner conductor when measured along a direction perpendicular to the third diameter of the proximal end portion . Further , the proximal end portion is equal to or smaller than the coaxial feed cable in a direction perpendicular to the fourth diameter .
  • any distance in a cross-sectional view on opposing points on an outer surface of the proximal end portion is larger than the corresponding distance on the inner conductor . Further optionally, any distance in a cross-sectional view on opposing points on an outer surface of the proximal end portion is equal to or smaller than the corresponding distance on the coaxial feed cable .
  • the proximal end portion optionally the whole instrument tip, is solid, for example free from cavities .
  • the solid configuration of the instrument tip or the proximal end portion is a simple implementation for providing a maximal volume , in particular a maximal outer surface area .
  • the proximal end portion is hollow .
  • the proximal end portion, the distal end portion, and/or the instrument tip include one or more cavities .
  • the hollow proximal end can define the same outer surface area or volume , e . g . by having the same outer diameter as a solid proximal end portion .
  • the hollowness of the proximal end portion or of the whole instrument tip does not significantly affect the emission characteristics of the instrument tip since the currents flowing in the instrument tip occur only close to the outer surface . This is due to the Skin effect .
  • the proximal end portion or the instrument tip may have wall thickness that is greater than the Skin depth in the frequency range of the emitted radiation . For example , the wall thickness is greater than 5pm - the Skin depth for 433 MHz is approximately 4 pm depending on the material of the instrument tip .
  • the wall thickness can be the difference between the outer diameter of the proximal end portion/instrument tip and the outer diameter of a cavity in the proximal end portion/instrument tip .
  • the proximal end portion may have the shape of a hollow cylinder .
  • the wall thickness corresponds to the thickness of the wall of the hollow cylinder and a single cavity is provided .
  • the proximal end portion may include a single cavity that extends from the distal end of the coaxial cable to the distal end portion.
  • the single cavity can be closed by the distal end portion and/or the coaxial cable.
  • the distal end portion may provide a cap to the cavity in the proximal end portion.
  • the proximal end portion or the instrument tip include a framework of wires or a mesh.
  • the framework of wires or the mesh of wires may define a single cavity so that the proximal end portion is hollow.
  • the wires or the mesh are made from an electrically conductive material.
  • the framework of wires or the mesh provide an outer surface area of conductive material.
  • framework of wires or the mesh have a thickness (a wall thickness) that is larger than the Skin depth.
  • the proximal end portion of the instrument tip has a (outer) shape of a cylinder.
  • the third minimal outer diameter and the fourth maximal outer diameter are equal to each other and correspond to the diameter of the cylinder.
  • the diameter of the cylinder may be between the first diameter and the second diameter and is optionally equal to the second diameter.
  • the shape of the cylinder provides the maximum volume defined by the proximal end portion in case of a tubular coaxial feed cable.
  • the diameter of the cylinder is equal to the second diameter for providing a maximal volume of the proximal end portion.
  • the second diameter and/or the fourth diameter are/is less than 1.5 mm, optionally less than 1.2 mm, further optionally 1.191 mm.
  • the coaxial cable may have a standard diameter of 0.47 inch or 1.191 mm.
  • the fourth diameter of the instrument is equal to or less than the diameter of the coaxial cable, i.e. equal to or less than 0.47 inch.
  • the distal end portion is rounded, pointed, or flattened.
  • a maximal outer diameter of the distal end portion and/or minimal outer diameter of the distal end portion may be smaller than the maximum outer diameter of the proximal end portion and/or the minimal outer diameter of the proximal end portion, respectively . This may be achieved by rounding or flattening the shape of the distal end portion compared to the proximal end portion . This may be done for facilitating the advancement of the instrument tip in the cavity of a person or human to be treated .
  • the distal end portion may be formed as a tip or spire .
  • the instrument tip may generally have the shape of a hollow or solid cylinder wherein the section of the distal end portion corresponding to a distal edge of the instrument tip is rounded or flattened .
  • the distal end portion is only a short section of the entire length of the instrument tip .
  • the distal end portion may be flattened so that the distal end may be considered having the shape of a blade .
  • the distal end portion is sharp for cutting tissue .
  • the proximal end portion has a length that is more than 50% , optionally more than 75% , further optionally more than 90% or 95 % , of a length of the instrument tip .
  • the distal end portion can be considered a tip of the instrument tip while the proximal end portion can be considered essentially defining nearly an entirety of the instrument tip .
  • the electrosurgical instrument is configured to provide microwave electromagnetic energy having a frequency between 433 MHz and 5 . 8 GHz , wherein optionally the instrument tip has a length which is smaller than a quarter of the wavelength of the microwave electromagnetic energy configured to be conveyed in the coaxial feed cable .
  • the configuration of the instrument tip to emit the microwave radiation has been described already .
  • the configuration of the coaxial cable to convey the microwave energy having a frequency between 433 MHz and 5 . 8 GHz can be understood in that the coaxial feed cable has an attenuation in this frequency range which results in a temperature increase of the coaxial feed cable which is acceptable when inserting the electrosurgical instrument into the cavity of a human or animal .
  • the heating of the coaxial cable due to the attenuation of the coaxial cable does not result in unwanted changes in the tissue in the proximity of the coaxial feed cable due to the heat of the coaxial feed cable .
  • the configuration of the coaxial feed cable to convey the microwave energy having a frequency between 433 MHz and 5 . 8 GHz can also be understood in that the energy level of the electromagnetic radiation that can be conveyed to the instrument tip is sufficiently high to treat the biological tissue .
  • the coaxial feed cable may have a characteristic impedance of 50 Q .
  • the length of the instrument (the sum of the lengths of the distal end portion and the proximal end portion) can be chosen to be shorter than a quarter of the wavelength conveyed by the electrosurgical instrument or the coaxial feed cable . If the electrosurgical instrument is configured to convey and emit microwave energy over a range of frequencies , the wavelength corresponding to the smallest lower limit of the frequency range ( e . g . 433 MHz ) may be chosen as the relevant frequency for determining the maximum length of the instrument tip .
  • the length of the instrument tip , of the proximal end portion, and/or of the distal end portion is measured perpendicular to the third and fourth outer diameter .
  • the length of the instrument tip is less than 7 mm, optionally 6 . 6 mm .
  • the instrument tip is exposed for contacting the biological tissue . This means that the instrument is not covered by a layer such as the cover layer or a sheath .
  • the material of the instrument is configured to be positioned to be in direct contact with the biological tissue for tissue treatment .
  • the outer conductor is spaced away from the instrument tip for preventing coupling between the outer conductor and the instrument tip .
  • the distance between the outer conductor and the instrument tip ( e . g . along the direction of extension of the electrosurgical instrument ) is large enough such that a capacitance between the instrument tip and the outer conductor is sufficiently small , i . e . the capacitive coupling between the outer conductor and the instrument tip does not significantly affect the functioning of the electrosurgical instrument .
  • the inner conductor and/or the dielectric material extend beyond the outer conductor .
  • the section between the instrument tip and the outer conductor may be considered an intermediate section .
  • the intermediate section includes the inner conductor, the dielectric material , and/or the cover layer . However , the intermediate section does not include the outer conductor .
  • the intermediate section may be considered not to be a coaxial cable due to the lack of the outer conductor . Thus , the intermediate section may be considered a bridge between the instrument tip and the coaxial cable .
  • the inner conductor and the dielectric material may extend beyond the outer conductor in a direction towards the distal end of the electrosurgical instrument or towards the instrument tip ( e . g . , a proximal end of the tip ) .
  • the intermediate section may be manufactured by removing the outer conductor in the area of the intermediate section . In this way, the instrument tip is electrically insulated from the outer conductor (e.g. , by the dielectric material extension) .
  • the inner conductor and the dielectric material contact the instrument tip (e.g. , a proximal end of the tip) .
  • the cover layer may also extend until the instrument tip.
  • a distance between the outer conductor and the instrument tip along the direction of extension of the electrosurgical instrument is more than 1 mm, optionally 1.3 mm, further optionally 1.5 mm. This distance may be considered corresponding to the length of the intermediate section.
  • proximal and distal refer to the ends of a structure (e.g. electrosurgical instrument, coaxial feed cable, etc. ) further from and closer to the treatment zone respectively.
  • proximal end of the structure is accessible by a user, whereas the distal end is closer to the treatment site, i.e. the patient.
  • conductive is used herein to mean electrically conductive unless the context dictates otherwise.
  • Fig. 1 is a schematic diagram of an electrosurgical apparatus
  • Fig. 2 is an enlarged perspective view of a distal section of an electrosurgical instrument of the electrosurgical apparatus of Fig. 1;
  • Fig. 3 is a cross-sectional view of a distal section of the electrosurgical instrument according to a further embodiment ;
  • Fig. 4 is a cross-sectional view of an instrument tip of the electrosurgical instrument according to a further embodiment ;
  • Fig . 5 is a cross-sectional view of an instrument tip of the electrosurgical instrument according to a further embodiment ;
  • Fig . 6 is a cross-sectional view of an instrument tip of the electrosurgical instrument according to a further embodiment ;
  • Fig . 7 is a side view of an instrument tip of the electrosurgical instrument according to yet a further embodiment .
  • Fig . 1 is a schematic diagram of an electrosurgical apparatus 10 .
  • the apparatus 10 is arranged to treat biological tissue (e . g . a tumour, lesion, or fibroid) using microwave electromagnetic (EM) energy delivered from an instrument tip 12 .
  • EM microwave electromagnetic
  • the electromagnetic energy emitted by the instrument tip 12 into a treatment zone can be used to coagulate and/or ablate tissue in the treatment zone .
  • the electrosurgical apparatus 10 further comprises a generator device 14 and an electrosurgical instrument 16 .
  • the generator device 14 comprises a generator unit for controllably generating microwave electromagnetic energy in a frequency range between 433 MHz and 5 . 8 GHz .
  • the generator 14 may include one or more generators each generating electromagnetic energy of a particular frequency so that the generator 14 generates electromagnetic energy at particular spot frequencies .
  • a suitable generator for this purpose is described in WO 2012 /076844 , which is incorporated herein by reference .
  • the generator 14 may be arranged to monitor reflected signals received back from the instrument tip 12 in order to determine an appropriate power level for delivery .
  • the generator 14 may be arranged to calculate an impedance seen at the instrument tip 12 in order to determine an optimal delivery power level.
  • the electrosurgical apparatus 10 further comprises a surgical scoping device 18, such as a bronchoscope, endoscope, gastroscope, laparoscope or the like.
  • the scoping device 18 may include a handpiece 20 and a flexible shaft 22.
  • the handpiece 20 may include means for guiding the flexible shaft 22 through a cavity of a body.
  • the handpiece 20 can include means for moving a distal end of the flexible shaft 22 to change direction of the distal end of the flexible shaft 22. This helps manoeuvring the flexible shaft 22 through the cavity of the body, such as the bronchial tubes of a lung.
  • the flexible shaft 22 may include a working channel through which elongated structures (e.g. the electrosurgical instrument 16) can be moved and, thus, positioned at the treatment zone within the cavity of the body.
  • the generator 14 can be configured to generate electromagnetic radiation at fixed or spot frequencies such as 433 MHz, 915 MHz, 2.45 GHz, and 5.8 GHz. However, the generator 14 is not limited thereto; the generator 14 can be configured to generate microwave electromagnetic energy in a continuous range between a minimum frequency (e.g. 433 MHz) and a maximum frequency (e.g. 5.8 GHz) . The frequency of the electromagnetic energy to be generated by the generator 14 may be selected using an interface (not shown in the figures) .
  • the generator 14 includes an output port to which a proximal end of the electrosurgical instrument 16 can be connected. A distal end of the electrosurgical instrument 16 is shown in Fig. 2.
  • the electrosurgical instrument 16 includes a coaxial feed cable 24 and the instrument tip 12.
  • the coaxial feed cable 24 includes an inner conductor 26, an outer conductor 28, and a dielectric material 30 separating the inner conductor 26 from the outer conductor 28. Further, the dielectric material 30 electrically insulates the inner conductor 26 from the outer conductor 28 .
  • the coaxial feed cable 24 may be covered by a cover layer which is not shown in the figures .
  • the instrument tip 12 is electrically connected to the inner conductor 26 .
  • the instrument tip 12 is solid, i . e . free from cavities , and is made from an electrically conductive material , such as stainless steel .
  • the instrument tip 12 is exposed so that it is configured to directly contact the biological tissue to be treated .
  • the electrosurgical instrument 16 includes an intermediate section 32 between the coaxial feed cable 24 and the instrument tip 12 .
  • the intermediate section 32 includes the inner conductor 26 and the dielectric material 30 , but does not include the outer conductor 28 . In other words , the inner conductor 26 and a dielectric material 30 protrude beyond the outer conductor 28 in a direction towards the instrument tip 12 .
  • the intermediate section 32 may have a length of 1 . 5 mm .
  • the instrument tip 12 in the embodiment shown in Fig . 2 has a shape of a cylinder having a diameter of 1 . 0 mm and a length of 6 . 6 mm .
  • the embodiment of Fig . 2 shows an instrument tip 12 having a constant diameter along its entire length .
  • the diameter of the instrument tip 12 is equal to the outer diameter of the coaxial feed cable 24 or to the outer diameter of the outer conductor 28 .
  • Fig . 3 shows a further embodiment of the electrosurgical instrument 16 which includes the same features and characteristics of the electrosurgical instrument 16 of Fig . 2 except for the following differences .
  • the instrument tip of Fig . 3 includes a proximal end portion 34 and a distal end portion 36 which have a different outer shape .
  • the proximal end portion 34 and the distal end portion 36 have the same outer shape .
  • the inner conductor 26 is connected to the proximal end portion 34 .
  • the distal end portion 36 is pointed having a sharp tip .
  • the inner conductor 26 has a first maximal outer diameter 38 and the coaxial feed cable 24 has a second maximal outer diameter 40 .
  • the proximal end portion 34 includes a minimal third outer diameter 42 and a maximal fourth outer diameter 44 .
  • the third diameter 42 is larger than the first diameter 38 and the fourth diameter 44 is equal to the second diameter 40 .
  • the proximal end portion 34 is thicker than the inner conductor 26 .
  • the maximal outer diameter of the proximal end portion 34 ( the fourth diameter ) is equal to or smaller than the outer diameter of the coaxial feed cable ( the second diameter ) . In other words , the proximal end portion 34 does not radially protrude beyond the coaxial feed cable 24 .
  • the distal end portion 36 also has a maximal outer diameter that is equal to or smaller than the second diameter . However, a minimal diameter of the distal end portion 36 can be smaller than the first diameter 38 . In the embodiment of Fig . 3 , the distal end portion 36 has a sharp tip and, therefore , a minimal diameter of zero .
  • Fig . 4 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 3 except for the following differences .
  • the proximal end portion 34 has the shape of a cylinder such that the third diameter 42 is equal to the fourth diameter 44 .
  • Fig . 5 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 4 except for the following differences .
  • the proximal end portion 36 is not pointed but rounded .
  • the instrument tip 12 of Fig . 5 generally has a cylindrical shape except for the rounded edge at the distal end portion 36 .
  • Fig . 6 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 4 except for the following differences .
  • the instrument tip 12 e . g . the proximal end portion 34 and the distal end portion 36 , is hollow .
  • a single cavity 46 extends from the proximal end of the proximal end portion 34 to the distal end of the distal end portion 36 .
  • the proximal end portion 34 has the shape of a hollow cylinder and the distal end portion 36 has the shape of a cone .
  • the hollow cylinder and the cone have a wall thickness 48 which corresponds to the difference between the third diameter 42 and/or fourth diameter 44 and the maximal outer diameter of the cavity 46 .
  • the wall thickness 48 is greater than the Skin depth at 433 MHz or, more generally, the Skin depth of the lowest frequency that the generator 14 can generate .
  • Fig . 7 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 6 except for the following differences .
  • the instrument tip 12 in particular the proximal end portion 34 and the distal end portion 36 , are made from a mesh of conductive material .
  • the instrument 12 has the same cavity 46 as shown in Fig . 6 , although this is not visible in Fig . 7 . This means that the mesh is shaped to provide the cavity 46 of Fig . 7 .

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Abstract

Various embodiments provide an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment. The instrument includes a coaxial feed cable including an inner conductor having a first maximal outer diameter, an outer conductor coaxial with the inner conductor, and a dielectric material separating the outer conductor and the inner conductor. The coaxial feed cable is for conveying the microwave electromagnetic energy and has a second maximal outer diameter. The instrument also includes an instrument tip made from an electrically conductive material. The instrument tip is for emitting the microwave electromagnetic energy. The instrument tip is electrically connected to the inner conductor and is electrically insulated from the outer conductor. The instrument tip includes a distal end portion and a proximal end portion that is closer to the coaxial feed cable than the distal end portion. The proximal end portion has a third minimal outer diameter and a fourth maximal outer diameter. The third diameter is larger than the first diameter. Some other embodiments relate to an electrosurgical apparatus comprising the electrosurgical instrument and a generator.

Description

Electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment
FIELD OF THE INVENTION
The invention relates to an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , wherein the electrosurgical instrument comprises a coaxial feed cable and an instrument tip . The coaxial feed cable includes an inner conductor having a first maximal outer diameter, an outer conductor coaxial with the inner conductor , and a dielectric material separating the outer conductor and the inner conductor . The coaxial feed cable is configured to convey the microwave electromagnetic energy and having a second maximal outer diameter . The instrument tip is configured to emit the microwave electromagnetic energy . The invention further relates to an electrosurgical apparatus comprising a generator and the electrosurgical instrument .
BACKGROUND TO THE INVENTION
Lung surgery can be performed using endoscopes . A diameter of bronchial tubes decreases the more the bronchial tube is away from the trachea . This means that a diameter of the endoscope needs to be small in order to reach end sections of bronchial tubes . A small diameter of the endoscope provides technical limitations for conveying electromagnetic energy for tissue treatment as well as for a radiating structure for emitting electromagnetic energy . For example , generally, the attenuation of a coaxial cable increases with the reduction of its diameter . Further, the attenuation of a coaxial cable increases with an increase in the frequency of the electromagnetic energy conveyed by the coaxial cable . Consequently, at a given frequency, the power carrying capability of a coaxial cable generally reduces as its diameter decreases , and the losses in the cable increase , and this becomes more severe at higher frequencies . Nevertheless , conveying microwave energy via a coaxial cable is probably the best method for treating lung tissue with microwave radiation .
The obj ective of the invention is to provide an electrosurgical instrument for conveying and emitting microwave electromagnetic energy having a small diameter so that the electrosurgical instrument is configured for endoscopic lung treatment .
SUMMARY OF THE INVENTION
It is an aim of the subj ect matter of the independent claims to solve this obj ective . Optional embodiments of the invention are defined in the dependent claims .
At its most general , the present invention provides an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , wherein the electrosurgical instrument includes a coaxial feed cable and an instrument tip for emitting electromagnetic energy conveyed by the coaxial feed cable , and wherein the instrument tip is configured to emit electromagnetic energy in a microwave frequency range while both the coaxial feed cable and the instrument tip have a small diameter .
According to a first aspect of the invention, there is provided an electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , comprising a coaxial feed cable and an instrument tip . The coaxial feed cable includes an inner conductor having a first maximal outer diameter, an outer conductor coaxial with the inner conductor , and a dielectric material separating the outer conductor and the inner conductor, the coaxial feed cable being for conveying the microwave electromagnetic energy and having a second maximal outer diameter . The instrument tip is made from an electrically conductive material and is configured to emit the microwave electromagnetic energy, e . g . , into the biological tissue . The instrument tip is electrically connected to the inner conductor and is electrically insulated from the outer conductor . The instrument tip includes a distal end portion and a proximal end portion that is closer to the coaxial feed cable than the distal end portion . The proximal end portion has a third minimal outer diameter and a fourth maximal outer diameter , wherein the third diameter is larger than the first diameter .
According to a second aspect of the invention, there is provided an electrosurgical apparatus for tissue treatment , comprising the electrosurgical instrument and a generator optionally configured to generate microwave electromagnetic energy having a frequency between 433 MHz and 5 . 8 GHz . The electrosurgical instrument can be used for coagulating and/or ablating biological tissue , such as lung tissue , by the emission of microwave electromagnetic energy into the biological tissue . The electrosurgical instrument , in particular a proximal end of the coaxial feed cable , may be connected to the generator that generates the microwave electromagnetic energy .
The electrosurgical instrument may be any instrument , or tool , which is used during surgery and which utilises microwave frequency energy . Herein, microwave radiation may mean electromagnetic radiation having a stable fixed frequency in the range between 300 MHz to 100 GHz . Optional spot frequencies for the microwave energy include 433 MHz , 915 MHz , 2 . 45 GHz , and 5 . 8 GHz . The generator may be configured to generate one or more of these spot frequencies .
The electrosurgical instrument may be an endoscopic instrument , i . e . an instrument that can be inserted into a cavity of a body for treating tissue close to or in the cavity of the body . For example , the electrosurgical instrument is configured to treat tissue at , within, or close to the cavity of the body such as a bronchial tube . The electrosurgical instrument may be suitable for use with an endoscope or another type of scoping device ( e . g . a bronchoscope ) . The electrosurgical instrument may be inserted into a catheter .
A first or proximal end of the coaxial feed cable is for connecting the cable to the generator for supplying the microwave frequency energy to the cable . The first end of the coaxial feed cable may have a terminal or connector for connecting the first or proximal end of the cable to the generator . Thus , the coaxial feed cable may be for conveying microwave frequency energy from a generator connected to the first (proximal ) end of the cable assembly to the instrument tip which is permanently connected ( e . g . directly or indirectly) to a second ( distal ) end of the coaxial feed cable .
The inner conductor and the outer conductor are coaxially arranged in order to form a coaxial cable capable of transmitting microwave energy . To this end, the outer conductor may completely or partially surround the inner conductor . In particular , an angular degree of extension of the inner conductor along a circumferential direction corresponds to an angular degree of extension of the outer conductor along the circumferential direction . That is , the inner conductor may be radially aligned with, or may radially overlap with, the outer conductor . The inner conductor and the outer conductor may not form a complete circle in a cross- sectional view of the coaxial cable . For example , the inner conductor and/or the outer conductor extend only to 3/ 4 , 4 /5 , or other ratios of the complete circumference of the coaxial layer .
Optionally, the inner conductor, the dielectric material , and/or the outer conductor have a ring shape in a cross- sectional view of the coaxial feed cable . In particular, the inner conductor, the dielectric material , and/or the outer conductor have a circular shape in the cross-sectional view of the coaxial feed cable . The inner conductor can be a solid body that extends along an axial direction of the coaxial feed cable .
The inner conductor and/or the outer conductor are made from an electrically conductive material , such as metal . The inner conductor and/or the outer conductor can be made from copper , aluminium, and/or tin .
The dielectric material is provided for electrically insulating the inner conductor from the outer conductor . The dielectric material may be made from an electrically insulating material . The dielectric material and/or the outer conductor may have a ring shape in a cross-sectional view of the coaxial feed cable , in particular a circular shape . The inner conductor, the outer conductor , and/or dielectric material can be coaxially arranged to each other .
The coaxial feed cable , in particular the outer conductor, may be covered or wrapped in a cover layer which is provided for mechanical strength, proofing ( e . g . protecting ) against entry of chemicals , such as water, and/or shielding the coaxial cable from mechanical damage . The cover layer may be made from a plastic material and can be electrically insulating .
The inner conductor, the dielectric material , the outer conductor, and/or the cover layer can continuously extend from the distal end to the proximal end of the coaxial feed cable .
The instrument tip may be permanently attached ( e . g . directly or indirectly) to the inner conductor at the distal end of the coaxial feed cable . The instrument tip is provided for emitting the electromagnetic energy that is conveyed by the coaxial feed cable from the generator . The instrument tip can be considered a monopole antenna . The instrument tip is electrically insulated from the outer conductor, for example by the dielectric material.
The instrument tip is made from electrically conductive material such as stainless steel which may be gold plated. Optionally, the instrument tip is entirely made from electrically conductive material. In other words, the instrument tip solely consists of electrically conductive material. The instrument tip is configured to emit electromagnetic energy as microwave radiation, optionally over a frequency range such as between 433 MHz and 5.8 GHz. Further, the instrument tip may be configured to emit microwave radiation at spot frequencies such as 433 MHz, 915 MHz, 2.45 GHz, and 5.8 GHz. The configuration of the instrument tip to emit radiation at certain frequency means that the transmission efficiency is sufficiently high for tissue treatment, i.e. the emitted electromagnetic radiation in the frequency range or at the spot frequencies has an intensity sufficient for tissue treatment (e.g. ablation and/or coagulation) . In particular, the back reflection at the instrument tip in the frequency range or at the spot frequencies is sufficiently low.
The instrument tip may consist of the proximal end portion and the distal end portion, i.e. the proximal end portion and a distal end portion make up the complete instrument tip. The proximal end portion and the distal end portion may differ in their outer shape. In this case, the distal end portion and the proximal end portion can be visibly distinguished. However, the proximal end portion and the distal end portion may have the same outer shape. In this case, the distal end portion and the proximal end portion cannot be visibly distinguished. The proximal end portion and a distal end portion may be a unitary component.
The first outer diameter refers to a maximum distance - in a cross-sectional view - between two opposing points on an outer surface of the inner conductor. In other words, the first outer diameter refers to the distance between that pair of opposing points on the outer surface of the inner conductor in a cross-sectional view which is the largest among the plurality of distances corresponding to any pairs of opposing points on the outer surface of the inner conductor . The first outer diameter corresponds to the mathematical definition of a diameter if the inner conductor has a circular outer surface in a cross-sectional view .
Similarly, the second outer diameter refers to a maximum distance - in a cross-sectional view - between two opposing points on an outer surface of the coaxial feed cable . In other words , the second outer diameter refers to the distance between that pair of opposing points on the outer surface of the coaxial feed cable in a cross-sectional view which is the largest among the plurality of distances corresponding to any pairs of opposing points on the outer surface of the outer conductor . The second outer diameter corresponds to the mathematical definition of a diameter if the coaxial feed cable has a circular outer surface in a cross-sectional view .
Similarly, fourth outer diameter refers to a maximum distance - in a cross-sectional view - between two opposing points on an outer surface of the proximal end portion . In other words , the fourth outer diameter refers to the distance between that pair of opposing points on the outer surface of the proximal end portion in a cross-sectional view which is the largest among the plurality of distances corresponding to any pairs of opposing points on the outer surface of the proximal end portion . The fourth outer diameter corresponds to the mathematical definition of a diameter if the proximal end portion has a circular outer surface in a cross-sectional view .
In an analogous manner , the third outer diameter refers to the minimal distance - in a cross-sectional view - between two opposing points on an outer surface of the proximal end portion . The third outer diameter corresponds to the mathematical definition of a diameter if the proximal end portion has a circular outer surface in a cross-sectional view .
The proximal end portion may have a shape having a varying diameter along its direction of extension . In this case , the proximal end portion has a minimal third outer diameter and a maximal fourth outer diameter . The minimal third outer diameter is larger than the first maximal outer diameter of the inner conductor . This means that the proximal end portion is thicker compared to the inner conductor over the entire length of the proximal end portion . Thus , a volume defined by the proximal end portion is greater than a volume of a section of the inner conductor having the same length as the proximal end portion . As a consequence , the outer surface area of the proximal end portion or the instrument tip can be increased with regard to the outer surface area of the inner conductor having the same length as the proximal end portion .
The inventors have surprisingly discovered that the characteristics of the instrument tip improve with the volume defined by the instrument tip . For example , the ratio of emitted electromagnetic radiation in relation to the electromagnetic energy conveyed by the coaxial feed cable increases with the volume defined the instrument tip . Further, the size of the frequency range of the electromagnetic radiation that can be emitted by the instrument tip increases with the volume defined by the instrument tip . This means that the instrument tip has better emission characteristics compared to a radiating structure that is constituted by only the inner conductor .
In an optional embodiment , the fourth diameter is smaller than or equal to the second diameter .
The second diameter may be constituted by the outer conductor or the cover layer arranged on the outer conductor . The second diameter defines a diameter of an opening into which the electrosurgical instrument can be inserted . The fourth diameter is smaller than or equal to the second diameter so that the proximal end does not radially protrude beyond the coaxial feed cable . This means that the proximal end portion and the coaxial feed cable can be inserted into the same opening .
The distal end portion may also have a maximum outer diameter which is smaller or equal to the second diameter . In this case , the instrument tip and the coaxial feed cable can be inserted into the same opening .
In view of the considerations above , it would be beneficial to have a fourth outer diameter that is larger than the second outer diameter in order to increase the volume defined the instrument tip . However, space considerations may prohibit this .
The inner conductor may have a fifth outer diameter that is perpendicular to the first maximal outer diameter . The coaxial feed cable has a sixth outer diameter that is perpendicular to the second maximal outer diameter . The proximal end portion has a seventh outer diameter that is perpendicular to third minimal outer diameter and an eighth outer diameter that is perpendicular to the fourth maximal outer diameter . The seventh diameter optionally is larger than the fifth diameter and the eighth diameter optionally is smaller than or equal to the sixth diameter .
In this embodiment , the proximal end portion is also thicker than the inner conductor when measured along a direction perpendicular to the third diameter of the proximal end portion . Further , the proximal end portion is equal to or smaller than the coaxial feed cable in a direction perpendicular to the fourth diameter . Optionally, any distance in a cross-sectional view on opposing points on an outer surface of the proximal end portion is larger than the corresponding distance on the inner conductor . Further optionally, any distance in a cross-sectional view on opposing points on an outer surface of the proximal end portion is equal to or smaller than the corresponding distance on the coaxial feed cable .
In an optional embodiment , the proximal end portion, optionally the whole instrument tip, is solid, for example free from cavities .
The solid configuration of the instrument tip or the proximal end portion is a simple implementation for providing a maximal volume , in particular a maximal outer surface area .
In an optional embodiment , the proximal end portion is hollow . For example , the proximal end portion, the distal end portion, and/or the instrument tip include one or more cavities .
In comparison to the solid embodiment of the instrument tip, the hollow proximal end can define the same outer surface area or volume , e . g . by having the same outer diameter as a solid proximal end portion . The hollowness of the proximal end portion or of the whole instrument tip does not significantly affect the emission characteristics of the instrument tip since the currents flowing in the instrument tip occur only close to the outer surface . This is due to the Skin effect . So , the proximal end portion or the instrument tip may have wall thickness that is greater than the Skin depth in the frequency range of the emitted radiation . For example , the wall thickness is greater than 5pm - the Skin depth for 433 MHz is approximately 4 pm depending on the material of the instrument tip . The wall thickness can be the difference between the outer diameter of the proximal end portion/instrument tip and the outer diameter of a cavity in the proximal end portion/instrument tip . For example , the proximal end portion may have the shape of a hollow cylinder . In this case , the wall thickness corresponds to the thickness of the wall of the hollow cylinder and a single cavity is provided .
The proximal end portion may include a single cavity that extends from the distal end of the coaxial cable to the distal end portion. The single cavity can be closed by the distal end portion and/or the coaxial cable. The distal end portion may provide a cap to the cavity in the proximal end portion.
In an optional embodiment, the proximal end portion or the instrument tip include a framework of wires or a mesh. The framework of wires or the mesh of wires may define a single cavity so that the proximal end portion is hollow. The wires or the mesh are made from an electrically conductive material. The framework of wires or the mesh provide an outer surface area of conductive material. For example, framework of wires or the mesh have a thickness (a wall thickness) that is larger than the Skin depth. Thus, currents can flow in the framework of wires or the mesh providing the emission of radiation.
In an optional embodiment, the proximal end portion of the instrument tip has a (outer) shape of a cylinder.
In this case, the third minimal outer diameter and the fourth maximal outer diameter are equal to each other and correspond to the diameter of the cylinder. The diameter of the cylinder may be between the first diameter and the second diameter and is optionally equal to the second diameter.
The shape of the cylinder provides the maximum volume defined by the proximal end portion in case of a tubular coaxial feed cable. Optionally, the diameter of the cylinder is equal to the second diameter for providing a maximal volume of the proximal end portion.
In an optional embodiment, the second diameter and/or the fourth diameter are/is less than 1.5 mm, optionally less than 1.2 mm, further optionally 1.191 mm.
The coaxial cable may have a standard diameter of 0.47 inch or 1.191 mm. As discussed above, the fourth diameter of the instrument is equal to or less than the diameter of the coaxial cable, i.e. equal to or less than 0.47 inch.
In an optional embodiment, the distal end portion is rounded, pointed, or flattened. A maximal outer diameter of the distal end portion and/or minimal outer diameter of the distal end portion may be smaller than the maximum outer diameter of the proximal end portion and/or the minimal outer diameter of the proximal end portion, respectively . This may be achieved by rounding or flattening the shape of the distal end portion compared to the proximal end portion . This may be done for facilitating the advancement of the instrument tip in the cavity of a person or human to be treated . The distal end portion may be formed as a tip or spire . For example , the instrument tip may generally have the shape of a hollow or solid cylinder wherein the section of the distal end portion corresponding to a distal edge of the instrument tip is rounded or flattened . In this case , the distal end portion is only a short section of the entire length of the instrument tip .
The distal end portion may be flattened so that the distal end may be considered having the shape of a blade . Optionally, the distal end portion is sharp for cutting tissue .
In an optional embodiment , the proximal end portion has a length that is more than 50% , optionally more than 75% , further optionally more than 90% or 95 % , of a length of the instrument tip . This means that , as outlined above , the distal end portion can be considered a tip of the instrument tip while the proximal end portion can be considered essentially defining nearly an entirety of the instrument tip .
In an optional embodiment , the electrosurgical instrument is configured to provide microwave electromagnetic energy having a frequency between 433 MHz and 5 . 8 GHz , wherein optionally the instrument tip has a length which is smaller than a quarter of the wavelength of the microwave electromagnetic energy configured to be conveyed in the coaxial feed cable .
The configuration of the instrument tip to emit the microwave radiation has been described already . The configuration of the coaxial cable to convey the microwave energy having a frequency between 433 MHz and 5 . 8 GHz can be understood in that the coaxial feed cable has an attenuation in this frequency range which results in a temperature increase of the coaxial feed cable which is acceptable when inserting the electrosurgical instrument into the cavity of a human or animal . In other words , the heating of the coaxial cable due to the attenuation of the coaxial cable does not result in unwanted changes in the tissue in the proximity of the coaxial feed cable due to the heat of the coaxial feed cable . Further , the configuration of the coaxial feed cable to convey the microwave energy having a frequency between 433 MHz and 5 . 8 GHz can also be understood in that the energy level of the electromagnetic radiation that can be conveyed to the instrument tip is sufficiently high to treat the biological tissue .
The coaxial feed cable may have a characteristic impedance of 50 Q . In order to match the impedance of the instrument tip to the impedance ( resistance ) of the coaxial feed cable , the length of the instrument ( the sum of the lengths of the distal end portion and the proximal end portion) can be chosen to be shorter than a quarter of the wavelength conveyed by the electrosurgical instrument or the coaxial feed cable . If the electrosurgical instrument is configured to convey and emit microwave energy over a range of frequencies , the wavelength corresponding to the smallest lower limit of the frequency range ( e . g . 433 MHz ) may be chosen as the relevant frequency for determining the maximum length of the instrument tip .
The length of the instrument tip , of the proximal end portion, and/or of the distal end portion is measured perpendicular to the third and fourth outer diameter .
In an optional embodiment , the length of the instrument tip is less than 7 mm, optionally 6 . 6 mm . In an optional embodiment , the instrument tip is exposed for contacting the biological tissue . This means that the instrument is not covered by a layer such as the cover layer or a sheath . The material of the instrument is configured to be positioned to be in direct contact with the biological tissue for tissue treatment .
In an optional embodiment , the outer conductor is spaced away from the instrument tip for preventing coupling between the outer conductor and the instrument tip .
For example , the distance between the outer conductor and the instrument tip ( e . g . along the direction of extension of the electrosurgical instrument ) is large enough such that a capacitance between the instrument tip and the outer conductor is sufficiently small , i . e . the capacitive coupling between the outer conductor and the instrument tip does not significantly affect the functioning of the electrosurgical instrument .
In an optional embodiment , the inner conductor and/or the dielectric material extend beyond the outer conductor .
The section between the instrument tip and the outer conductor may be considered an intermediate section . The intermediate section includes the inner conductor, the dielectric material , and/or the cover layer . However , the intermediate section does not include the outer conductor . The intermediate section may be considered not to be a coaxial cable due to the lack of the outer conductor . Thus , the intermediate section may be considered a bridge between the instrument tip and the coaxial cable . The inner conductor and the dielectric material may extend beyond the outer conductor in a direction towards the distal end of the electrosurgical instrument or towards the instrument tip ( e . g . , a proximal end of the tip ) . The intermediate section may be manufactured by removing the outer conductor in the area of the intermediate section . In this way, the instrument tip is electrically insulated from the outer conductor (e.g. , by the dielectric material extension) .
In an optional embodiment, the inner conductor and the dielectric material contact the instrument tip (e.g. , a proximal end of the tip) . Further, the cover layer may also extend until the instrument tip.
In an optional embodiment, a distance between the outer conductor and the instrument tip along the direction of extension of the electrosurgical instrument is more than 1 mm, optionally 1.3 mm, further optionally 1.5 mm. This distance may be considered corresponding to the length of the intermediate section.
Herein, the terms "proximal" and "distal" refer to the ends of a structure (e.g. electrosurgical instrument, coaxial feed cable, etc. ) further from and closer to the treatment zone respectively. Thus, in use the proximal end of the structure is accessible by a user, whereas the distal end is closer to the treatment site, i.e. the patient.
The term "conductive" is used herein to mean electrically conductive unless the context dictates otherwise.
BRIEF DESCRIPTION OF THE DRAWINGS
Examples of the invention are discussed below with reference to the accompanying drawings, in which:
Fig. 1 is a schematic diagram of an electrosurgical apparatus ;
Fig. 2 is an enlarged perspective view of a distal section of an electrosurgical instrument of the electrosurgical apparatus of Fig. 1;
Fig. 3 is a cross-sectional view of a distal section of the electrosurgical instrument according to a further embodiment ; Fig . 4 is a cross-sectional view of an instrument tip of the electrosurgical instrument according to a further embodiment ;
Fig . 5 is a cross-sectional view of an instrument tip of the electrosurgical instrument according to a further embodiment ;
Fig . 6 is a cross-sectional view of an instrument tip of the electrosurgical instrument according to a further embodiment ; and
Fig . 7 is a side view of an instrument tip of the electrosurgical instrument according to yet a further embodiment .
DETAILED DESCRIPTION; FURTHER OPTIONS AND PREFERENCES
Fig . 1 is a schematic diagram of an electrosurgical apparatus 10 . The apparatus 10 is arranged to treat biological tissue ( e . g . a tumour, lesion, or fibroid) using microwave electromagnetic ( EM) energy delivered from an instrument tip 12 . The electromagnetic energy emitted by the instrument tip 12 into a treatment zone can be used to coagulate and/or ablate tissue in the treatment zone .
The electrosurgical apparatus 10 further comprises a generator device 14 and an electrosurgical instrument 16 . The generator device 14 comprises a generator unit for controllably generating microwave electromagnetic energy in a frequency range between 433 MHz and 5 . 8 GHz . The generator 14 may include one or more generators each generating electromagnetic energy of a particular frequency so that the generator 14 generates electromagnetic energy at particular spot frequencies . A suitable generator for this purpose is described in WO 2012 /076844 , which is incorporated herein by reference . The generator 14 may be arranged to monitor reflected signals received back from the instrument tip 12 in order to determine an appropriate power level for delivery . For example, the generator 14 may be arranged to calculate an impedance seen at the instrument tip 12 in order to determine an optimal delivery power level.
The electrosurgical apparatus 10 further comprises a surgical scoping device 18, such as a bronchoscope, endoscope, gastroscope, laparoscope or the like. The scoping device 18 may include a handpiece 20 and a flexible shaft 22. The handpiece 20 may include means for guiding the flexible shaft 22 through a cavity of a body. For example, the handpiece 20 can include means for moving a distal end of the flexible shaft 22 to change direction of the distal end of the flexible shaft 22. This helps manoeuvring the flexible shaft 22 through the cavity of the body, such as the bronchial tubes of a lung. The flexible shaft 22 may include a working channel through which elongated structures (e.g. the electrosurgical instrument 16) can be moved and, thus, positioned at the treatment zone within the cavity of the body.
The generator 14 can be configured to generate electromagnetic radiation at fixed or spot frequencies such as 433 MHz, 915 MHz, 2.45 GHz, and 5.8 GHz. However, the generator 14 is not limited thereto; the generator 14 can be configured to generate microwave electromagnetic energy in a continuous range between a minimum frequency (e.g. 433 MHz) and a maximum frequency (e.g. 5.8 GHz) . The frequency of the electromagnetic energy to be generated by the generator 14 may be selected using an interface (not shown in the figures) .
The generator 14 includes an output port to which a proximal end of the electrosurgical instrument 16 can be connected. A distal end of the electrosurgical instrument 16 is shown in Fig. 2.
The electrosurgical instrument 16 includes a coaxial feed cable 24 and the instrument tip 12. The coaxial feed cable 24 includes an inner conductor 26, an outer conductor 28, and a dielectric material 30 separating the inner conductor 26 from the outer conductor 28. Further, the dielectric material 30 electrically insulates the inner conductor 26 from the outer conductor 28 . The coaxial feed cable 24 may be covered by a cover layer which is not shown in the figures .
The instrument tip 12 is electrically connected to the inner conductor 26 . The instrument tip 12 is solid, i . e . free from cavities , and is made from an electrically conductive material , such as stainless steel . The instrument tip 12 is exposed so that it is configured to directly contact the biological tissue to be treated .
The electrosurgical instrument 16 includes an intermediate section 32 between the coaxial feed cable 24 and the instrument tip 12 . The intermediate section 32 includes the inner conductor 26 and the dielectric material 30 , but does not include the outer conductor 28 . In other words , the inner conductor 26 and a dielectric material 30 protrude beyond the outer conductor 28 in a direction towards the instrument tip 12 . The intermediate section 32 may have a length of 1 . 5 mm .
The instrument tip 12 in the embodiment shown in Fig . 2 has a shape of a cylinder having a diameter of 1 . 0 mm and a length of 6 . 6 mm . Thus , the embodiment of Fig . 2 shows an instrument tip 12 having a constant diameter along its entire length . The diameter of the instrument tip 12 is equal to the outer diameter of the coaxial feed cable 24 or to the outer diameter of the outer conductor 28 .
Fig . 3 shows a further embodiment of the electrosurgical instrument 16 which includes the same features and characteristics of the electrosurgical instrument 16 of Fig . 2 except for the following differences .
The instrument tip of Fig . 3 includes a proximal end portion 34 and a distal end portion 36 which have a different outer shape . In the embodiment of Fig . 2 , the proximal end portion 34 and the distal end portion 36 have the same outer shape . Turning to the embodiment of Fig . 3 , the inner conductor 26 is connected to the proximal end portion 34 . The distal end portion 36 is pointed having a sharp tip .
The inner conductor 26 has a first maximal outer diameter 38 and the coaxial feed cable 24 has a second maximal outer diameter 40 . The proximal end portion 34 includes a minimal third outer diameter 42 and a maximal fourth outer diameter 44 . The third diameter 42 is larger than the first diameter 38 and the fourth diameter 44 is equal to the second diameter 40 . This means that the proximal end portion 34 is thicker than the inner conductor 26 . However, the maximal outer diameter of the proximal end portion 34 ( the fourth diameter ) is equal to or smaller than the outer diameter of the coaxial feed cable ( the second diameter ) . In other words , the proximal end portion 34 does not radially protrude beyond the coaxial feed cable 24 .
The distal end portion 36 also has a maximal outer diameter that is equal to or smaller than the second diameter . However, a minimal diameter of the distal end portion 36 can be smaller than the first diameter 38 . In the embodiment of Fig . 3 , the distal end portion 36 has a sharp tip and, therefore , a minimal diameter of zero .
Fig . 4 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 3 except for the following differences .
The proximal end portion 34 has the shape of a cylinder such that the third diameter 42 is equal to the fourth diameter 44 .
Fig . 5 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 4 except for the following differences .
The proximal end portion 36 is not pointed but rounded .
So the instrument tip 12 of Fig . 5 generally has a cylindrical shape except for the rounded edge at the distal end portion 36 .
Fig . 6 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 4 except for the following differences .
The instrument tip 12 , e . g . the proximal end portion 34 and the distal end portion 36 , is hollow . A single cavity 46 extends from the proximal end of the proximal end portion 34 to the distal end of the distal end portion 36 . The proximal end portion 34 has the shape of a hollow cylinder and the distal end portion 36 has the shape of a cone . The hollow cylinder and the cone have a wall thickness 48 which corresponds to the difference between the third diameter 42 and/or fourth diameter 44 and the maximal outer diameter of the cavity 46 . The wall thickness 48 is greater than the Skin depth at 433 MHz or, more generally, the Skin depth of the lowest frequency that the generator 14 can generate .
Fig . 7 shows a further embodiment of the instrument tip 12 which includes the same features and characteristics of the instrument tip 12 of Fig . 6 except for the following differences .
The instrument tip 12 , in particular the proximal end portion 34 and the distal end portion 36 , are made from a mesh of conductive material . The instrument 12 has the same cavity 46 as shown in Fig . 6 , although this is not visible in Fig . 7 . This means that the mesh is shaped to provide the cavity 46 of Fig . 7 .

Claims

1 . An electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment , comprising : a coaxial feed cable including an inner conductor having a first maximal outer diameter , an outer conductor coaxial with the inner conductor , and a dielectric material separating the outer conductor and the inner conductor, the coaxial feed cable being for conveying the microwave electromagnetic energy and having a second maximal outer diameter ; and an instrument tip made from an electrically conductive material , the instrument tip being for emitting the microwave electromagnetic energy, the instrument tip being electrically connected to the inner conductor and being electrically insulated from the outer conductor , the instrument tip including a distal end portion and a proximal end portion that is closer to the coaxial feed cable than the distal end portion, and proximal end portion having a third minimal outer diameter and a fourth maximal outer diameter , wherein the third diameter is larger than the first diameter .
2 . The electrosurgical instrument of claim 1 , wherein the fourth diameter is smaller than or equal to the second diameter .
3 . The electrosurgical instrument of claims 1 or 2 , wherein the instrument tip is solid .
4 . The electrosurgical instrument of claims 1 or 2 , wherein the proximal end portion is hollow .
5 . The electrosurgical instrument of claim 4 , wherein the proximal end portion includes a framework of wires or a mesh .
6 . The electrosurgical instrument of any preceding claim, wherein the proximal end portion of the instrument tip has a shape of a cylinder .
7 . The electrosurgical instrument of any preceding claim, wherein the distal end portion is rounded or pointed .
8 . The electrosurgical instrument of any preceding claim, wherein the second diameter and/or the fourth diameter are/is less than 1 . 5 mm, optionally less than 1 . 2 mm, further optionally 1 . 191 mm.
9 . The electrosurgical instrument of any preceding claim, wherein the electrosurgical instrument is configured to convey microwave electromagnetic energy having a frequency between 433 MHz and 5 . 8 GHz , wherein the instrument tip has a length which is smaller than a quarter of the wavelength of the microwave electromagnetic energy configured to be conveyed in the electrosurgical instrument .
10 . The electrosurgical instrument of claim 9 , wherein the length of the instrument tip is less than 7 mm, optionally 6 . 6 mm .
11 . The electrosurgical instrument of any preceding claim, wherein the instrument tip is exposed for contacting the biological tissue .
12 . The electrosurgical instrument of any preceding claim, wherein the outer conductor is spaced away from the instrument tip for preventing coupling between the outer conductor and the instrument tip .
13 . The electrosurgical instrument of claim 12 , wherein the inner conductor and the dielectric material extend beyond the outer conductor .
14 . The electrosurgical instrument of claim 12 or 13 , wherein the inner conductor and the dielectric material contact the instrument tip .
15 . The electrosurgical instrument of any one of claims 12 to 14 , wherein a distance between the outer conductor and the instrument tip along a direction of extension of the electrosurgical instrument is more than 1 mm, optionally 1 . 3 mm, further optionally 1 . 5 mm.
16 . The electrosurgical instrument of any preceding claim, wherein the proximal end portion has a length that is more than 50% , optionally more than 75% , further optionally more than 90% , of a length of the instrument tip .
17 . An electrosurgical apparatus for tissue treatment , comprising the electrosurgical instrument of any preceding claim, and a generator configured to generate microwave electromagnetic energy having a frequency between 433 MHz and
5 . 8 GHz .
PCT/EP2023/066742 2022-07-14 2023-06-21 Electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment WO2024012822A1 (en)

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GBGB2210323.8A GB202210323D0 (en) 2022-07-14 2022-07-14 Electrosurgical instrument for conveying and emitting microwave electromagnetic energy into biological tissue for tissue treatment

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