HK40073264A - Electrosurgical instrument - Google Patents

Description

Electrosurgical instrument

Technical Field

The present invention relates to an electrosurgical instrument for delivering radiofrequency and microwave energy to biological tissue for cutting and coagulating tissue. The electrosurgical instrument may be particularly suitable for flexible endoscopy, e.g., sized to pass through an instrument channel of an endoscope. However, the present invention may be applicable to other types of procedures, such as rigid laparoscopy or open surgery.

Background

Surgical resection is a method of removing unwanted tissue portions associated with organs in the human or animal body, such as the liver or spleen or intestine. When cutting (dissecting or transecting) tissue, small blood vessels, known as arterioles, can be damaged or ruptured. Initial bleeding is followed by a coagulation cascade, during which blood becomes a clot in an attempt to block the bleeding site. During surgery, it is desirable to have the patient lose as little blood as possible, and therefore various devices have been developed in an attempt to provide a bloodless cut.

For example,the thermal scalpel system combines a sharp blade with a hemostatic system. The blades being coated with plastics material and connected to precisely control blade temperatureThe heating unit of (1). The purpose is for the heated blade to cauterize tissue as it cuts.

Other known devices that cut and stop bleeding at the same time do not use a blade. Some devices use Radio Frequency (RF) energy to cut and/or coagulate tissue. Other devices, known as harmonic scalpels, use a rapidly vibrating tip to cut tissue.

The method of cutting using RF energy operates using the following principles: when an electrical current is passed through the tissue matrix (aided by the ionic content of the cells), the impedance to the flow of electrons through the tissue generates heat. When a pure sine wave is applied to the tissue matrix, sufficient heat is generated within the cells to evaporate the water of the tissue. Therefore, the intracellular pressure is greatly increased without being controlled by the cell membrane, resulting in cell rupture. When this occurs over a large area, it is foreseeable that the tissue has been severed.

RF coagulation operates by: a less efficient waveform is applied to the tissue whereby the cell contents are heated to about 65 c rather than being vaporized. This dries out the tissue by drying and denatures the proteins in the vessel wall and the collagen that makes up the cell wall. Denaturing the protein stimulates the coagulation cascade, thereby enhancing coagulation. At the same time, collagen in the cell wall is denatured from rod-like molecules to coil molecules, which causes the blood vessels to contract and decrease in size, giving the clot an anchoring point and a smaller occluded area.

Applying thermal energy to biological tissue is also an effective method of killing cells. For example, the application of microwaves can heat and thus ablate (destroy) biological tissue. The method may be particularly useful for treating cancer, as cancerous tissue may be ablated in this manner.

Disclosure of Invention

In general, the present invention provides an electrosurgical instrument that is capable of simultaneously ablating a tissue region with microwave energy and ablating with RF energy. The instrument has a distal bipolar energy delivery tip with a pencil-like profile for emitting a focused RF field to facilitate precise cutting of biological tissue.

According to the present invention, there may be provided an electrosurgical instrument comprising: a coaxial transmission line for transmitting Radio Frequency (RF) energy and microwave energy; an energy delivery tip coupled to a distal end of the coaxial transmission line, wherein the energy delivery tip comprises: a first electrode electrically coupled to the inner conductor of the coaxial transmission line and protruding (projecting) beyond the distal end of the outer conductor of the coaxial transmission line; a second electrode electrically coupled to the outer conductor of the coaxial transmission line and extending coaxially along a portion of the first electrode; and a dielectric disposed between the first electrode and the second electrode, wherein: the first electrode comprises a projecting nib (projecting nib) projecting beyond a distal end of the dielectric; the second electrode and dielectric include a portion exposed at a distal end of the energy delivery tip; and the first and second electrodes are configured as (i) a bipolar structure for delivering RF energy transmitted by the coaxial transmission line, and (ii) an antenna for radiating microwave energy transmitted by the coaxial transmission line.

With the above structure, the instrument of the present invention provides focused delivery of RF energy at the protruding tip (protruding nib), which helps to achieve precise cutting by "drawing" the cutting line using the device as a pen. Advantageously, the energy delivery unit is further configured to deliver microwave energy to all fast coagulations in case of bleeding. The RF and microwave energy may be applied separately or simultaneously.

To achieve optimal focusing of the RF energy, the energy delivery tip may have a distally facing end surface comprising an exposed portion of the dielectric and an exposed portion of the second electrode arranged concentrically around the protruding tip. Thus, the instrument may resemble a bull's-eye, viewed from the front, with the protruding nib at its center. The instrument may thus have rotational symmetry about a central longitudinal axis (e.g. the axis of a coaxial transmission line) such that the current effect is uniform regardless of the orientation of the instrument.

The distal-facing end surface may be shaped (profiled) to focus the delivered RF energy at the protruding tip. Shaping the distal end face may also aid visibility, i.e., by ensuring that the operator can see the protruding prongs.

In one example, the distally facing end surface may be tapered, i.e. tapered in a linear manner towards the protruding tip. The angle of the tapered surface may be selected to facilitate visibility and field focusing. In one example, the distal-facing end surface may be at a 45 ° angle to the longitudinal axis of the protruding tip.

In another example, the distal-facing end surface may be rounded, such as dome-shaped or hemispherical. With a protruding tip, this configuration can give the energy delivery tip a bottle-nose (bottolene) appearance. The exposed portion of the dielectric body preferably protrudes to the more distal side than the distal end of the exposed portion of the second electrode.

The first electrode may be formed by a distally extending portion of the inner conductor. In other words, the inner conductor may extend uninterrupted from the coaxial transmission line through the energy delivery tip to form a protruding tip.

However, in other examples, the first electrode may be a separate component from the inner conductor. It may be coupled to the inner conductor by a connecting rod. The connecting rod may be another component or may be integrally formed with the first electrode. An advantage of this configuration is that the dimensions of the connecting bar and/or the first electrode can be selected independently. This may help adjust the impedance of the energy delivery tip for microwave energy, as discussed below.

The connecting rod may include a proximal sheath secured over an outer surface of the distal end of the inner conductor. The first electrode may thus be connected as an extension of the inner conductor. The connecting rod may be connected to the inner conductor by any suitable technique, but a mechanical connection (e.g., crimping) may be preferred.

The second electrode may include a conductive sleeve having a proximal portion coated on the distal portion of the outer conductor. The conductive sleeve may be electrically connected and physically secured to the outer conductor in the proximal portion. For example, the conductive sleeve may be secured to the outer conductor by crimping.

The instrument may further comprise an outer insulating jacket (jack) arranged to cover a distal portion of the coaxial transmission line and a proximal portion of the energy delivery tip. The jacket can protect the coaxial transmission line and the energy delivery tip and prevent energy from leaking from structures other than the distal tip.

The antenna may be configured as an impedance transformer for coupling microwave energy into biological tissue. In other words, the energy delivery tip may be configured to transform the impedance of the coaxial transmission line to a typical tissue impedance for microwave energy. For example, the lengths of the first electrode, the dielectric, and the second electrode may be selected such that the energy delivery tip operates as a quarter wave transformer of microwave energy.

The instrument may be sized to fit through an instrument channel of a surgical scoping device. For example, the instrument may have a maximum outer diameter equal to or less than 2.0 mm. In some examples, the instrument may be further miniaturized to have a maximum outer diameter equal to or less than 1.0 mm. The protruding nibs may have a diameter equal to or less than 0.2 mm. The protruding nib may have a length equal to or less than 1.0 mm.

The term "surgical scoping device" may be used herein to mean any surgical device provided with an insertion tube, which is a rigid or flexible (e.g., steerable) catheter that is introduced into a patient during an invasive procedure. The insertion tube may include an instrument channel and an optical channel (e.g., for transmitting light to illuminate and/or capture images of a treatment site located at a distal end of the insertion tube). The instrument channel may have a diameter suitable for receiving an invasive surgical tool. The instrument channel may have a diameter of 5mm or less. In an embodiment of the invention, the surgical scoping device can be an ultrasonic endoscope.

In this context, the term "inner" means radially closer to the center (e.g., axis) of the instrument channel and/or coaxial cable. The term "outer" means radially further from the center (axis) of the instrument channel and/or coaxial cable.

The term "conductive" is used herein to mean electrically conductive, unless the context indicates otherwise.

As used herein, the terms "proximal" and "distal" refer to the ends of an elongate probe. In use, the proximal end is closer to the generator for providing RF and/or microwave energy, while the distal end is further from the generator.

In the present specification, "microwave" may be widely used to indicate a frequency range of 400MHz to 100GHz, but is preferably a range of 1GHz to 60 GHz. Preferred nominal frequencies of microwave EM energy include: 915MHz, 2.45GHz, 3.3GHz, 5.8GHz, 10GHz, 14.5GHz and 24 GHz. 5.8GHz may be preferred. The device may deliver energy at more than one of these microwave frequencies.

The term "radio frequency" or "RF" may be used to indicate frequencies between 300kHz and 400 MHz.

Drawings

Embodiments of the invention are discussed below with reference to the accompanying drawings, in which:

fig. 1 is a schematic view showing an electrosurgical apparatus as an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of an instrument cord passing through an endoscope that may be used with the present invention;

FIG. 3 is a cross-sectional view of the distal end of an electrosurgical instrument as an embodiment of the present invention;

FIG. 4 is a cross-sectional view of the distal end of an electrosurgical instrument as another embodiment of the present invention;

FIG. 5 is a perspective view of the electrosurgical instrument of FIG. 4; and is

Fig. 6 is a cross-sectional view of the distal end of an electrosurgical instrument as another embodiment of the present invention.

Detailed Description

Fig. 1 is a schematic view of an electrosurgical apparatus 100 configured to supply radiofrequency energy and microwave energy to a distal end of an invasive electrosurgical instrument. In this example, the device may also be configured to deliver a fluid, such as a cooling fluid, but this is not required. The system 100 includes a generator 102 for controllably supplying Radio Frequency (RF) and microwave energy. Generators suitable for this purpose are described in WO 2012/076844, which is incorporated herein by reference. The generator may be arranged to monitor reflected signals received back from the instrument in order to determine a power level suitable for delivery. For example, the generator may be arranged to calculate the impedance observed at the distal end of the instrument in order to determine the optimal delivered power level.

The generator 102 is connected to an interface joint 106 via an interface cable 104. The interface joint 106 is also connected to a fluid delivery device 108, such as a syringe, via a fluid flow line 107. In some examples, the apparatus may additionally or alternatively be arranged to aspirate fluid from the treatment site. In such a case, the fluid flow line 107 may convey fluid from the interface joint 106 to a suitable collector (not shown). A suction mechanism may be connected at the proximal end of the fluid flow line 107.

If desired, the interface joint 106 may house an instrument control mechanism that may be operated by a sliding trigger, for example, to control longitudinal (back and forth) movement of one or more control wires or push rods (not shown). If there are multiple control wires, there may be multiple sliding triggers on the interface to provide full control. The interface joint 106 functions to combine inputs from the generator 102, the fluid delivery device 108, and the instrument control mechanism into a single flexible shaft 112, the flexible shaft 112 extending from a distal end of the interface joint 106.

The flexible shaft 112 may be inserted through the entire length of an instrument channel (also referred to as a working channel) of a surgical scoping device 114, which surgical scoping device 114 may include an endoscope in embodiments of the invention.

The surgical scoping device 114 includes a body 116, the body 116 having a plurality of input ports, and an output port from which an instrument cord 120 extends. The instrument cord 120 includes an outer jacket surrounding a plurality of lumens. The plurality of lumens convey various objects (ings) from the body 116 to the distal end of the instrument cord 120. One of the plurality of lumens is the instrument channel discussed above. Other lumens may include channels for transmitting optical radiation, for example to provide illumination at or acquire images from the distal end. The body 116 may include an eye piece (eye piece)122 for viewing the distal end.

The flexible shaft 112 has a distal assembly 118 (not drawn to scale in fig. 1), the distal assembly 118 being shaped to pass through the instrument channel of the surgical scoping device 114 and project at the distal end of the instrument cord (e.g., project into the patient).

The distal end assembly 118 may be any electrosurgical instrument discussed below. The distal end assembly 118 may be specifically designed for use with conventional endoscopes. For example, the maximum outer diameter of the distal end assembly 118 may be equal to or less than 2.0mm, e.g., less than 1.9mm (and more preferably less than 1.5mm), and the length of the flexible shaft may be equal to or greater than 1.2 m. In other examples, the structure may be configured for even smaller spaces. For example, the maximum outer diameter of the distal end assembly 118 may be equal to or less than 1.0 mm.

The main body 116 includes a power input port 128 for connection to the flexible shaft 112. As explained below, the proximal portion of the flexible shaft may include a conventional coaxial cable capable of transmitting radiofrequency and microwave energy from the generator 102 to the distal assembly 118. The coaxial cables available that can physically fit down the instrument channel of the endoscope have the following outer diameters: 1.19mm (0.047 inch), 1.35mm (0.053 inch), 1.40mm (0.055 inch), 1.60mm (0.063 inch), 1.78mm (0.070 inch). Custom sized coaxial cables having even smaller diameters (e.g., 0.8mm or less) may also be used.

As discussed above, it is desirable to be able to control the position of at least the distal end of the instrument cord 120. The body 116 may include a control actuator that is mechanically coupled to the distal end of the instrument cord 120 by one or more control wires (not shown) extending through the instrument cord 120. The control wires may run within the instrument channel or within their own dedicated channel. The control actuator may be a rod or a rotatable knob or any other known catheter manipulation device. The steering instrument cord 120 may be software-assisted, for example, using a virtual three-dimensional map assembled from Computed Tomography (CT) images.

Fig. 2 is a view along the axis of the instrument cord 120. In this embodiment, there are four lumens within the instrument cord 120. The largest lumen is the instrument channel 132. Other lumens may include a pair of illumination channels 136, 138 and a camera channel 134. However, the present invention is not limited to this configuration. For example, there may be other lumens, for example, for control wires or fluid delivery or aspiration.

Fig. 3 is a cross-sectional view of the distal end of an electrosurgical instrument 200 as an embodiment of the present invention. The instrument 200 is a generally cylindrical elongate member that includes a flexible coaxial transmission line 202 and a distal energy delivery tip 212. The flexible coaxial transmission line 202 may be a coaxial cable that extends back (e.g., through an instrument channel of a surgical scoping device) to the generator. The coaxial transmission line 202 may be configured to transmit Radio Frequency (RF) energy and microwave energy separately or simultaneously. As explained in more detail below, the distal energy delivery tip 212 may be configured to provide a bipolar element for focused delivery of RF energy for tissue cutting and coagulation. The distal energy delivery tip 212 may be further configured as an antenna for radiating microwave energy into tissue for coagulation or ablation.

The coaxial transmission line 202 includes an inner (center) conductor 204 separated from a concentrically arranged outer conductor 208 by a dielectric (electrically insulating) layer 206. The outer surface of the outer conductor 208 is covered by a jacket 210 that provides protection and electrically insulates the outer conductor 208.

The distal end of the coaxial transmission line 202 is connected to a distal energy delivery tip 212. The distal energy delivery tip 212 includes a dielectric 216 extending in a longitudinal direction toward the distal end of the instrument. The longitudinal direction is aligned with the coaxial cable axis at the distal end of the coaxial cable. The dielectric 216 may be generally cylindrical and may have an outer diameter less than the outer diameter of the coaxial transmission line 202. The dielectric 216 may be made of the same or different material as the dielectric layer 206 in the coaxial transmission line 202.

The dielectric body 216 has a hollow longitudinally extending passage therethrough. The channel may be machined to the appropriate dimensions. At the proximal end, a channel in the dielectric 216 accommodates the portion of the inner conductor 204 that extends beyond the distal end of the dielectric layer 206. The inner conductor 204 is electrically coupled to the first electrode 220. The first electrode 220 comprises a rod element including a distal portion disposed in the channel of the dielectric 216 and a distal-most proximal portion protruding (exposed) from the energy delivery tip 212. In this example, the first electrode 220 is electrically (and physically) coupled to the inner conductor 204 through the tie bar 218. The tie bar 218 may be made of an electrically conductive material, such as the same material as the inner conductor 204 and/or the first electrode 220. The connecting rod 218 may have a proximal sleeve portion fixed (e.g., by a crimp 224) on the distal portion of the inner conductor 204. The first electrode 220 may be integrally formed with the tie bar 218 or may be a separate component secured to the tie bar.

In practice, the distal energy delivery tip 212 may be manufactured by:

stripping the dielectric layer 206 and the outer conductor 208 from the distal length of the inner conductor 204;

securing the tie bar 218 to the exposed inner conductor 204;

the dielectric body 216 is formed around the connecting rod, for example, by winding, molding, or the like.

Energy delivery tip 212 further includes a second electrode 214 comprising a conductive sleeve mounted about a dielectric 216. The conductive sleeve is electrically coupled to the outer conductor 208 of the coaxial transmission line. In this example, a proximal portion of the conductive sleeve is electrically and physically coupled to a distal portion of the outer conductor 208 by a crimp 222.

A jacket 210 made of an insulating material extends beyond the coaxial transmission line 202 to cover a portion of the conductive sleeve. However, jacket 210 terminates short of the distal end of energy delivery tip 212, thereby exposing distal end portion 230 of second electrode 214.

The distal end of the energy delivery tip 212 is thus similar to a bulls-eye, which includes: a central protruding prong as part of the first electrode 220; the exposed portion 232 of the dielectric 216; and an exposed portion 230 of the second electrode 214 separated from the first electrode by the dielectric 216. The distal most side of the protruding tip 220 may be rounded, for example to prevent snagging on biological tissue when in use.

This structure provides a bipolar structure for delivering RF energy. The first electrode 220 and the second electrode 214 form a source and a return of a bipolar structure. The effect of the bulls-eye configuration is to create a preferential energy flow along the most distal surface, resulting in an increased energy density at and around the central cusp. This energy distribution facilitates cutting. The instrument can be operated like a pen because the cutting action occurs preferentially at the protruding tip. Focusing of the RF energy may occur because the conductive surface area of the protruding tines 220 is less than the surface area of the exposed portions 230. The focused energy distribution may mean that the cut starts from the protruding tip. Thus, the device is intuitive to use.

The distal end of energy delivery tip 212 may be shaped in a manner that facilitates energy delivery or operation. For example, in fig. 3, the bullseye has a pointed (e.g., conical) profile in which the exposed portion 230 of the second electrode 214 and the exposed portion 232 of the dielectric 216 are sloped toward the protruding tip 220. The angle of inclination may preferably be in the range 30 ° to 60 °, preferably 45 °.

In addition to delivering RF energy to cut biological tissue, the distal energy delivery tip 212 may also be configured as a microwave antenna for delivering microwave energy for coagulation. The relative dimensions of the connecting rod 218 and the first electrode 220, the dielectric 216, and the second electrode 214 may be selected to ensure that the energy delivery tip 212 has an impedance suitable for coupling microwave energy into biological tissue. In one example, the energy delivery tip 212 may be configured as a quarter wave transformer at the frequency of the microwave energy transmitted by the coaxial transmission line 202. This arrangement helps to couple microwave energy into the tissue.

The structure may have a size suitable for insertion through an instrument channel of a surgical scoping device, such as an endoscope or the like. For example, the coaxial transmission line 202 may be a coaxial cable having an outer diameter of 1.6 mm. The second electrode 214 may have a maximum outer diameter of 2.0 mm. The radial gap between the inner surface of the second electrode 214 and the first electrode 220 (or the tie bar 218), i.e., the minimum radial thickness of the dielectric 216 between the first and second electrodes, may be 0.4 mm. The protruding nib 220 may have a maximum diameter of 0.2 mm.

The instrument may be able to be further miniaturized. For example, the coaxial cable may have an outer diameter of 0.8mm, such that the entire device may fit through a channel having a diameter of 1.0 mm.

Fig. 4 is a cross-sectional view of the distal end of an electrosurgical instrument 240 as another embodiment of the present invention. Features in common with figure 3 are given the same reference numerals and will not be described again.

The electrosurgical instrument 240 of fig. 4 differs from that of fig. 3 in that the profile of the energy delivery tip 212 has a bottle nose shape. This is defined by an exposed end surface 244 of the second electrode having a rounded (e.g., dome-shaped) distal end that is curved into a circle to meet the rounded exposed portion 242 of the dielectric 216. The exposed portion 242 of the dielectric 216 extends distally beyond a distal end of the exposed portion 244 of the second electrode 214.

Fig. 5 shows a perspective view of the electrosurgical instrument 240 of fig. 4.

Fig. 6 is a cross-sectional view of the distal end of an electrosurgical instrument 250 as another embodiment of the present invention. Features in common with figure 4 are given the same reference numerals and will not be described again.

Electrosurgical instrument 240 of fig. 6 differs from that of fig. 4 in that the distal-most tip of the protruding tine 220 has an insulating cap 252 formed thereon. The insulating cap 252 can help shape the RF field between the exposed portion 244 of the second electrode 214 and the exposed portion of the protruding tip 220. For example, it may prevent RF energy from entering paths located further than the distal-most end of the instrument. The insulative cap 252 may also provide a smooth (e.g., rounded) surface to avoid causing undesirable tissue damage as the instrument is navigated to the treatment site.

Claims (15)

1. An electrosurgical instrument, comprising:

a coaxial transmission line for conveying Radio Frequency (RF) energy and microwave energy;

an energy delivery tip coupled to a distal end of the coaxial transmission line, wherein the energy delivery tip comprises:

a first electrode electrically coupled to the inner conductor of the coaxial transmission line and protruding beyond the distal end of the outer conductor of the coaxial transmission line;

a second electrode electrically coupled to the outer conductor of the coaxial transmission line and extending coaxially along a portion of the first electrode; and

a dielectric disposed between the first electrode and the second electrode,

wherein:

the first electrode includes a protruding tip that protrudes beyond the distal end of the dielectric;

the second electrode and the dielectric include a portion exposed at a distal end of the energy delivery tip; and is

The first and second electrodes are configured as (i) a bipolar structure for delivering RF energy transmitted by the coaxial transmission line; and (ii) an antenna for radiating microwave energy transmitted by the coaxial transmission line.

2. The electrosurgical instrument of claim 1, wherein the energy delivery tip has a distally facing end surface comprising an exposed portion of the dielectric body and an exposed portion of the second electrode concentrically arranged about the protruding tip.

3. The electrosurgical instrument of claim 2, wherein the distal-facing end surface is shaped to focus delivered RF energy at the protruding tip.

4. An electrosurgical instrument according to claim 2 or 3, wherein the distal-facing end surface is tapered.

5. The electrosurgical instrument of claim 3, wherein the distal-facing end surface is at a 45 ° angle to a longitudinal axis of the protruding tip.

6. An electrosurgical instrument according to claim 2 or 3, wherein the distal-facing end surface is rounded.

7. An electrosurgical instrument according to any preceding claim, wherein the first electrode is formed by a distally extending portion of the inner conductor.

8. The electrosurgical instrument of any one of claims 1 to 6, wherein the first electrode is coupled to the inner conductor via a connecting rod.

9. The electrosurgical instrument of claim 8, wherein the connecting rod comprises a proximal sheath secured to an outer surface of the inner conductor.

10. An electrosurgical instrument according to claim 8 or 9, wherein the connecting rod is connected to the inner conductor by crimping.

11. An electrosurgical instrument according to any preceding claim, wherein the second electrode comprises a conductive sleeve having a proximal portion coated over a distal portion of the outer conductor.

12. An electrosurgical instrument according to claim 11, wherein the conductive sleeve is secured to the outer conductor by crimping.

13. An electrosurgical instrument according to any preceding claim, further comprising an outer insulating jacket arranged to cover a distal portion of the coaxial transmission line and a proximal portion of the energy delivery tip.

14. An electrosurgical instrument according to any preceding claim, wherein the antenna is configured as an impedance transformer for coupling the microwave energy into biological tissue.

15. The electrosurgical instrument of claim 14, wherein the lengths of the first, dielectric, and second electrodes are selected to cause the energy delivery tip to operate as a quarter wave transformer for the microwave energy.