WO2013160851A1

WO2013160851A1 - A high-frequency electromagnetic energy active ablation device

Info

Publication number: WO2013160851A1
Application number: PCT/IB2013/053243
Authority: WO
Inventors: Valentina Lara GARBAGNATI
Original assignee: Garbagnati Valentina Lara
Priority date: 2012-04-24
Filing date: 2013-04-24
Publication date: 2013-10-31
Also published as: ITMI20120677A1; EP2877112A1

Abstract

A high-frequency ablation device comprising: a hollow member, with an insulating outer coating and at least one opening arranged in the portion of a free distal part; at least one high-frequency active electrode housed within the hollow member, configured to shift from an inactive position within the hollow member to an active position outside; a thrust member connected to a proximal end of said at least one electrode, configured to shift the electrode from the inactive position to the active position outside the hollow member, and to allow the escape of an operative substance from said at least one opening; said at least one active electrode being configured so that, when the distal end of the at least one electrode is in the active position, it intersects a plane orthogonal to the longitudinal axis of the hollow member passing through said at least one opening.

Description

"A high-frequency electromagnetic energy active ablation device"

DESCRIPTION

The present invention relates to mini-invasive techniques of tissue thermo-ablation in the medical surgical field that use high-frequency electromagnetic energy, in particular to a high-frequency electromagnetic energy-induced thermal ablation device, for example, a radiofrequency or a microwaves ablation device.

Thermal ablation devices by high-frequency electromagnetic energy-induced hyperthermia, for example, radiofrequency, are known and are commonly used for treating parenchymal (liver, lung, kidney, and so on) tumors, or in the cardiovascular field (ablation of abnormal bundles of cardiac nervous fibers, trans-arterial renal denervation, and so on).

A thermo-ablation device of a known type is composed of a needle- active electrode that is jointed to a radiofrequency generator, in turn jointed to a dispersive electrode (conductive metal plate). The dispersive electrode is located on the patient's skin to close the electric circuit. The needle-active electrode is composed of a metal member (stem, or hollow member) coated with an insulating plastic material throughout its length, except on the tip, for a length ranging from 1.0 mm to 3.0 cm (exposed active part). Such devices are capable of producing tissue thermal lesions (thermo-lesions) having a predefined volume around their active tip when they are inserted into parenchymatous organs and electromagnetic energy is supplied.

In the case of the above-mentioned first radiofrequency monopolar devices, the volume of the produced thermo-lesions is reduced, and it can be only slightly increased by increasing the gauge and length of the exposed tip of the active electrode, or by changing the exposure time and the supplied power (maximum diameter of the thermo-lesions with a needle- electrode having a gauge of 1.1 and 1.8 mm: 14 mm and 18 mm, respectively). This occurs because, when the temperature in the tissue adhering to the active tip of the needle-electrode reaches 100° C (at atmospheric pressure), it causes the fluids to boil and also a tissue dehydration, which causes a rapid increase of the device impedance and the discontinuation of the energy supply. Therefore, when using such devices, the treatment of tumors with a diameter even less than 3.0 cm requires multiple insertions of the active tip of the needle-electrode in the tumor.

In order to obtain thermo-lesions with a larger volume so as to treat larger tumors, two new types of needles-electrode have been created: those so-called "cooled" and the so-called "expansible" ones.

The needles-electrode "cooled" get a volume increase of the thermo-lesion by keeping the temperature in the tissue adherent to the active tip of the electrode of below the boiling point of the tissue fluids during the procedure. Such temperature control is ensured by the passage of cooled water within the same electrode (the passage of water subtracts heat from the active tip). The delay in reaching the boiling and evaporation point of the fluids in the tissue adhered to the active part of the electrode (corresponding to the rapid increase of impedance and the discontinuation of the energy supply), allows the storage in the tissue of higher amount of energy and thus the creation of thermo-lesions of having a larger volume (maximum diameter with needles-electrode with a gauge of 1.4 mm: 24 mm).

The "expansible" needles-electrode get a volume increase of the thermo-lesion by increasing the contact surface between the active part of the electrode and the tissue. This has been obtained by making active threadlike electrodes contained inside the same device to go out from the device active tip (needle-active electrode). Most of the tissue adhering to the active part of the electrode, while keeping the supplied power constant, requires a longer time to be dehydrated, therefore it allows the storage in the tissue of higher amount of energy and the creation of thermo-lesions having a larger volume (maximum diameter with needles-electrode with a gauge of 1.4 mm: 30-32 mm).

The "expansible" needles-electrode are composed of a hollow member coated with an insulating plastic material throughout its length, except on the tip (exposed active part: from 1.0 mm to 3.0 cm length) containing one or more threadlike electrodes. Each threadlike electrode is active and shifts along a main longitudinal development direction of the insulated hollow member between an inactive position in which the end of the threadlike electrode is within the hollow member, and an active position in which the end of the threadlike electrode is outside the hollow member. Such threadlike electrodes, in their distal end that shifts from the inactive position to the active one, have a preformed morphology with shape memory which can be linear, curvilinear, helicoidal, or spiral-shaped.

Each above-described ablation device is not free from defects.

The stem device produces thermo-lesions that are too small to ablate tumors with a diameter even less than 3.0 cm, and it is to be considered as outdated.

The creation of "cooled" and "expansible" devices required an increase in the gauge (traversal diameter) of the same device compared to the stem devices. Such gauge increase is necessary to insert into the device the cooling circuit in the first case, and the shape-memory threadlike electrodes in the second case.

Unfortunately, the needle-electrode gauge has a relevant importance in clinical practice, since, as it is known, the gauge increase of the needles-electrode is associated to an increase of the complication rate related to the imaging-guided insertion thereof into the tumor. Furthermore, the thermo-ablation procedure with large gauge needles is more invasive, poorly tolerated by the patient, and it needs a deep sedation or general anesthesia of the patient in order to be carried out. Furthermore, a large gauge needle-electrode is poorly maneuverable, and this limits the number of possible insertions in the positioning step of its active tip into the tumor.

Last but not least, a large gauge needle-electrode has a negative psychological effect to the operator. All this is in sharp contrast with the need to use minimally invasive percutaneous procedures.

Furthermore, the ablation devices of the prior art, described before, offer non-optimal performance as regards ablative efficiency and repeatability of the thermo-lesions, i.e., they are not able to ensure thermo- lesions with high volumes, independently from the resistivity of the tissue type to be ablated (very vascularized tissue, not very vascularized tissue, high fat content tissue, low fat content tissue, and so on).

The object of the present invention is to provide a high-frequency electromagnetic energy active ablation device (for example, a radiofrequency ablation device) capable of obviating the drawbacks set forth herein above with reference to the prior art, in particular, which allows obtaining a high ablative efficiency and repeatability, independently from the resistivity of the tissue to be ablated.

Further object of the present invention is to provide a high- frequency electromagnetic energy active ablation device that is capable of ensuring thermo-lesions having a volume larger than that obtained with known needles-electrodes having the same gauge or, alternatively, thermo- having a volume identical to that obtained with known needles-electrodes having a larger gauge.

Such object is achieved by an ablation device in accordance with claim 1.

Preferred embodiments of such ablation device are defined in the appended dependent claims.

Further characteristics and advantages of the ablation device according to the invention will be apparent from the description set forth herein below of preferred implementation examples, given by way of indicative, non-limiting example, with reference to the appended Figures, in which:

Figs. 1a and 1b schematically illustrate, according to an example of the invention, an overall perspective view of an ablation device with a high- frequency active electrode in an inactive position (Fig. 1a) and with a high- frequency active electrode in an active position (Fig. b);

Figs. 2a, 2b, 2c and 2d illustrate views in a section transversal to the main longitudinal development direction of the ablation device of examples of ablation devices according to the invention;

Figs. 3a and 3b illustrate, in a sectional view along the main longitudinal development direction of the ablation device, a portion of device with two high-frequency active electrodes according to a further example of the invention, in an inactive position (Fig. 3a) and in an active position (Fig. 3b), respectively;

Figs. 4a and 4b illustrate, in a sectional view along the main longitudinal development direction of the ablation device, a portion of device with two high-frequency active electrodes according to a further example of the invention, in an inactive position (Fig. 4a) and in an active position (Fig. 4b), respectively, and

Figs. 5a and 5b illustrate, in a sectional view along the main longitudinal development direction of the ablation device, a portion of device with two high-frequency active electrodes according to a further example of the invention, in an inactive position (Fig. 5a) and in an active position (Fig. 5b), respectively.

With reference to the above-mentioned Figures, a high-frequency electromagnetic energy active ablation device has been indicated with the reference DDA, for example, radiofrequency or microwaves, herein below also referred to simply as an ablation device or device, according to the invention on the whole.

The ablation device DDA can be used in the medical surgical field for the treatment by radiofrequency or microwaves-induced interstitial hyperthermia of tumor masses located in parenchymatous organs, or in the cardiovascular field for endovascular treatments of diseases related to hypertension treatments.

The ablation device DDA comprises a bearer hollow member 1 , preferably tubular, extending along a respective main longitudinal development direction X, provided with an insulating outer coating 2 throughout its length, with a proximal end operatively connected to a handle 3, for example in a plastic material, and a free distal part 4.

The bearer hollow member 1 comprises a distal opening 8, for example, transversal to the main longitudinal development direction X of the bearer hollow member 1.

In the example of Figs. 1a and 1b, the bearer hollow member 1 is provided with the insulating outer coating 2 throughout its length, except for the free distal part 4 (exposed active surface) thereof. However, in another embodiment, not shown in the Figure, the insulating outer coating 2 may coat the entire bearer hollow member 1.

In an embodiment, the bearer hollow member 1 is a hollow cylinder, made of a rigid material, for example, medical steel, and the insulating outer coating 2 in a medical plastic material.

In another embodiment, alternative to the previous one, not shown in the Figures, the bearer hollow member 1 is a catheter, made of a rigid or soft medical plastic material, and containing both the active electrode and a passage channel for a guide wire.

Generally, as illustrated in the Figures, the ablation device DDA comprises at least one high-frequency active electrode 5, herein below also referred to simply as "at least one electrode" or "an electrode", which is housed within the bearer hollow member 1. The at least one electrode 5 is configured to shift along the main longitudinal development direction X of the bearer hollow member 1 to bring the free distal end 6 of the electrode 5 from an inactive position, within the bearer hollow member 1 (Fig. 1a), to an active position, outside the bearer hollow member 1 (Fig. 1b), for example, through the distal opening 8 of the bearer hollow member 1.

The at least one electrode 5 is operatively jointed to an electric connector allowing the connection to a high-frequency electromagnetic energy generator (for example, radiofrequency or microwaves), neither of which being illustrated in the Figures.

The at least one electrode 5, as illustrated in the examples of Figs. 2a, 2b, 2c and 2d, in a section transversal to the main longitudinal development direction X of the bearer hollow member 1 , advantageously has a geometric shape comprising at least one substantially angle-shaped portion 9.

According to an example of the present invention (Fig. 2a), the substantially angle-shaped portion 9 of the at least one electrode 5 comprises a substantially curvilinear line 10 and a further substantially curvilinear line 10' jointed to one another to form such substantially angle- shaped portion 9. The ends of the substantially curvilinear line 10 and of the further substantially curvilinear line 10', opposite to the ends forming such substantially angle-shaped portion 9, are jointed to one another to form a further substantially angle-shaped portion 9'.

According to another example of the present invention (Fig. 2b), the substantially angle-shaped portion 9 of the at least one electrode 5 comprises a substantially rectilinear line 11 and a substantially curvilinear line 10 jointed to one another to form such substantially angle-shaped portion 9. The ends of the substantially rectilinear line 11 and of the substantially curvilinear line 10 opposite to the ends forming such substantially angle-shaped portion 9, are jointed to one another to form a further angle-shaped portion 9'.

According to other implementation examples of the present invention (Fig. 2c and Fig. 2d), the substantially angle-shaped portion 9 of the at least one electrode 5 comprises a substantially rectilinear line 11 and a further substantially rectilinear line 1 Γ jointed to one another to form such substantially angle-shaped portion 9, the ends of the substantially rectilinear line 11 and of the further substantially rectilinear line 11 ', opposite to the ends forming such substantially angle-shaped portion 9, are jointed by a substantially curvilinear line 10. It shall be noticed that also each of joint point of a substantially rectilinear line 11 with a substantially curvilinear line 10 represents a substantially angle-shaped portion 9'.

In accordance with a further embodiment (not shown in the Figures), the at least one electrode 5, in a section transversal to the main longitudinal development direction X of the bearer hollow member 1 , has a substantially circular section.

In accordance with a further embodiment (not shown in the Figures), the at least one electrode 5, in a first section transversal to the main longitudinal development direction X of the bearer hollow member 1 , advantageously has a geometric shape comprising at least one substantially angle-shaped portion 9. Furthermore, the at least one electrode 5, in a second section transversal to the main longitudinal development direction X of the bearer hollow member 1 , different from the first section, has a substantially circular section.

It shall be noticed that Fig. 2a shows an ablation device DDA with 5 an electrode 5; Fig. 2b shows an ablation device DDA with a first electrode 5 and a second electrode 5'; Fig. 2c shows an ablation device DDA with a first electrode 5, a second electrode 5', and a third electrode 5"; Fig. 2d shows an ablation device DDA with a first electrode 5, a second electrode 5', a third electrode 5", and a fourth electrode 5"'. The ablation device DDA

10 may generally comprise a plurality of radiofrequency active electrodes according to the present invention.

Furthermore, it is pointed out that said at least one electrode 5 can be shaped to define a passage channel inside which a guide wire can be housed, parallel to the main longitudinal development direction X of the i s bearer hollow member 1. In a completely similar manner, a plurality of active electrodes in accordance with the present invention can be configured and/or distributed within the bearer hollow member 1 to define a passage channel inside which a guide wire can be housed, parallel to the main longitudinal development direction of the bearer hollow member 1.

20 Such embodiments of the ablation device (an example of which can be that illustrated in Fig. 2a) are used preferably in the case that the bearer hollow member 1 is a catheter.

Generally referring back to the at least one electrode 5, it shall be observed that it can be constructed to operate with both the monopolar

25 (with dispersive electrode) or bipolar techniques, per se known. Furthermore, the at least one electrode 5 can be provided with one or more thermistors, not shown in the Figures, arranged in any point of the at least one electrode 5, in order to detect and control the temperatures of the electrode itself.

The at least one electrode 5 is preferably manufactured in a shape memory material, i.e., able to make it to take the predetermined shape that the heat during the manufacturing process imposed thereto, for example, a thermoforming process, so as to take the predetermined shape when it passes from an inactive position to an active position, i.e., when it is moved outside the bearer hollow member 1.

In an implementation example, the active distal end of said at least one electrode 5 is arc of a circle-shaped, as shown in the example of Figs. 1b, 3a-5b. In other implementation examples, the predetermined shape of the at least one electrode can be linear, curvilinear, helicoidal, spiral- shaped, or another geometric shape.

Examples of conductive materials with shape memory commonly used to produce high-frequency active electrodes are medical steel and nitinol, also belonging to the metals family. It shall be noticed that the at least one electrode 5 can be made of any other metal or material, provided it is conductive for high-frequency electromagnetic energy.

In the embodiment shown in the Figs. 3a and 3b, as already stated before, the bearer hollow member 1 comprises the distal opening 8. Through such distal opening 8, a plane P1 substantially orthogonal to the main longitudinal development direction X of the bearer hollow member 1 virtually passes. The plane P1 is indicated in Fig. 3b with a broken line. Furthermore, the bearer hollow member 1 comprises at least one side opening 13 arranged in the portion of the free distal part 4 lacking in the insulating outer coating 2. Through such at least one side opening 13, a plane P2 substantially orthogonal to the main longitudinal development direction of the bearer hollow member 1 virtually passes. The plane P2 is indicated in Fig. 3b with a broken line. The at least one side opening 13 has been schematically illustrated also in Fig. 1b.

A thrust member 12 is connected to the proximal end 16 of said at least one electrode 5. The proximal end of the thrust member 12 ends on the mobile thrust joint 7 of the handle 3 (neither of which are shown in the Figs. 3a and 3b) of the ablation device DDA.

The thrust member 12 is configured to shift along the main longitudinal development direction X of the bearer hollow member 1 to bring the free distal end 6 of said at least one electrode 5 from the inactive position inside the bearer hollow member 1 to the active position outside the bearer hollow member 1.

Furthermore, the thrust member 12 is advantageously configured to allow the escape of an operative substance 17 from at least one opening of the bearer hollow member 1. Such at least one opening can be the distal opening 8 or said at least one side opening 13.

In a further embodiment, the thrust member 12 is advantageously configured to allow the escape of an operative substance 17 from the distal opening 8 and from said at least one side opening 13 of the bearer hollow member 1.

It shall be noticed that the operative substance 17 is present, since it is injected from the outside, in the thrust member 12.

The operative substance 17 can be, for example, a gel, a physiological solution, a radioactive substance, a group of micro particles that are inert or loaded with therapeutic agents, a contrast means, and so 5 on.

Referring back to the embodiment of Figs. 3a and 3b, it is pointed out that, generally, the at least one active electrode 5 is advantageously configured so that, when the free distal end 6 of the at least one electrode 5 is in the active position, the free distal end 6 intersects the plane P1 (or P2)

10 orthogonal to the longitudinal development direction X of the bearer hollow member 1 passing through said at least one opening (the distal opening 8 or said at least one side opening 13) of the bearer hollow member 1.

Referring again to the embodiment of Figs. 3a and 3b, in the case that said at least one opening is said at least one side opening 13, the i s thrust member 12, in more detail, comprises a hollow cylinder with at least one side opening 14 at the distal end 15 thereof to which the proximal end 16 of the at least one electrode 5 is secured.

Such configuration, when the free distal end 6 of said at least one electrode 5 is moved from an inactive position to an active position, allows

20 the substantial alignment between the at least one side opening 14 of the thrust member and the at least one side opening 13 of the bearer hollow member 1 (as shown for example in Fig. 3b). In this manner, the escape from the at least one side opening 13 of the bearer hollow member 1 and from the at least one side opening 14 of the thrust member 12 of the 5 operative substance 17 injected into the thrust member 12 is possible. In accordance with a further embodiment, in the case that said at least one opening of the bearer hollow member 1 is the distal opening 8, the thrust member 12 comprises a hollow cylinder with at least one side opening 14 at the distal end 15 thereof to which the proximal end 16 of said at least one electrode 5 is secured. When the free distal end 6 of the at least one electrode 5 is in the active position, the at least one side opening 14 of the thrust member 12 is in a position along the main longitudinal development direction X of the bearer hollow member 1 such as to allow the escape of the operative substance 17, injected into the thrust member 12, from the distal opening 8.

A further embodiment of the ablation device DDA is shown in the Figs. 4a and 4b.

As already stated before, the bearer hollow member 1 comprises the distal opening 8. Through such distal opening 8, a plane P1 substantially orthogonal to the main longitudinal development direction X of the bearer hollow member 1 virtually passes. The plane P1 is indicated in Fig. 4b with a broken line.

Furthermore, the bearer hollow member 1 comprises at least one side opening 13 arranged in the portion of the free distal part 4 lacking in the insulating outer coating 2. Through such at least one side opening 13, a plane P2 substantially orthogonal to the main longitudinal development direction of the bearer hollow member 1 virtually passes. The plane P2 is indicated in Fig. 4b with a broken line.

A thrust member 12 is connected to the proximal end 16 of said at least one electrode 5. The proximal end of the thrust member 12 ends on the mobile thrust joint 7 of the handle 3 (neither of which are shown in the Figs. 4a and 4b) of the ablation device DDA.

Furthermore, the thrust member 12 is advantageously configured to allow the escape of an operative substance 17 (already described before) from at least one opening of the bearer hollow member 1. Such at least one opening can be the distal opening 8 or said at least one side opening 13.

Referring back to the embodiment of Figs. 4a and 4b, it is pointed out that, generally, the at least one active electrode 5 is advantageously configured so that, when the free distal end 6 of the at least one electrode 5 is in the active position, the free distal end 6 intersects the plane P1 (or P2) orthogonal to the longitudinal development direction X of the bearer hollow member 1 passing through said at least one opening (the distal opening 8 or said at least one side opening 13) of the bearer hollow member 1.

Referring again to the embodiment of Figs. 4a and 4b, the thrust member 12 is piston-shaped, comprising a cylindrical base 23 transversal to the main longitudinal development direction X of the bearer hollow member 1 jointed to a stem 24, or alternatively a hollow development cylinder, which is parallel to the main longitudinal development direction X of the bearer hollow member 1.

Such stem 24 has the proximal end connected to the thrust joint 7 of the handle 3 of the ablation device DDA, described before, but not shown in the Figs. 4a and 4b.

The cylindrical base 23 is configured so that when the free distal end 6 of said at least one electrode 5 is in the active position, is in a position along the main longitudinal development direction X of the bearer hollow member 1 such as to allow the escape from said at least one opening of the bearer hollow member 1 of the operative substance 17 (as shown for example in Fig. 4b). Examples of the operative substance 17 have been described before.

In accordance with an embodiment, the at least one opening from which the operative substance 17 escapes is the distal opening 8 of the bearer hollow member 1.

In accordance with a further embodiment, alternatively or in combination with the previous embodiment, the at least one opening from which the operative substance 17 escape is further the at least one side opening 13 of the bearer hollow member 1.

A further embodiment is shown in the Figs. 5a and 5b.

As already stated before, the bearer hollow member 1 comprises the distal opening 8. Through such distal opening 8, a plane P1 substantially orthogonal to the main longitudinal development direction X of the bearer hollow member 1 virtually passes. The plane P1 is indicated in Fig. 5b with a broken line.

Furthermore, the bearer hollow member 1 comprises at least one side opening 13 arranged in the portion of the free distal part 4 lacking in the insulating outer coating 2. Through such at least one side opening 13, a plane P2 substantially orthogonal to the main longitudinal development direction of the bearer hollow member 1 virtually passes. The plane P2 is indicated in Fig. 5b with a broken line.

A thrust member 12 is connected to the proximal end 16 of said at least one electrode 5. The proximal end of the thrust member 12 ends on the mobile thrust joint 7 of the handle 3 (neither of which are shown in the Figs. 5a and 5b) of the ablation device DDA.

Referring back to the embodiment of Figs. 5a and 5b, it is pointed out that, generally, the at least one active electrode 5 is advantageously configured so that, when the free distal end 6 of the at least one electrode 5 is in the active position, the free distal end 6 intersects the plane P1 (or P2) orthogonal to the longitudinal development direction X of the bearer hollow member 1 passing through said at least one opening (the distal opening 8 or said at least one side opening 13) of the bearer hollow member 1.

The thus-configured thrust member 12, when the free distal end 6 of said at least one electrode 5 is in the active position, is in a position along the main longitudinal development direction X of the bearer hollow member 1 such as to allow the escape from said at least one opening of the bearer hollow member 1 of the operative substance 17 (as shown for example in Fig. 5b). Examples of such operative substance have already been provided before.

In accordance with a further embodiment, the at least one opening from which the operative substance 17 escapes is the at least one side opening 13 of the bearer hollow member 1.

In accordance with a further embodiment, the at least one opening from which the operative substance 17 escapes is both the distal opening 8 and the at least one side opening 13.

Furthermore, in more detail, the thrust member 12 of the embodiment of Figs. 5a and 5b is piston-shaped, with a cylindrical base 23 transversal to the main longitudinal development direction X of the bearer hollow member 1 jointed to a hollow development cylinder 25, which is parallel to the main longitudinal development direction X of the bearer hollow member 1. The hollow cylinder 25 further comprises a partition wall 18 parallel to the main longitudinal development direction X of the bearer hollow member 1 adapted to define a first insertion cavity 20 and a second evacuation cavity 21 , for example, both semi-cylindrical, of a cooling substance 22, for example in a liquid or gaseous form, of the free distal part 4 of the ablation device DDA. In more detail, the partition wall 18 is adapted to end in the proximity of the distal end 15 of the thrust member 12 to define a communication opening 19 between the first insertion cavity 20 and the second evacuation cavity 21. In such configuration, a cooling substance 22 coming from the first insertion cavity 20 may reach the distal end 15 of the thrust member 12 jointed to the proximal end 16 of the at least one electrode 5 and may leave such distal end 15 through the second evacuation cavity 21 , passing through the communication opening 19.

Furthermore, it shall be noticed that in such position the cylindrical base 23 of the thrust member 12 turns out to be at the free distal part 4 of the bearer hollow member 1. In this manner, by activating the circulation of the cooling substance 22 within the thrust member 12, the cooling of the free distal part 4 lacking in the insulating outer coating 2 of the bearer hollow member 1 of the ablation device DDA is obtained.

In a further embodiment, not shown in the Figures, the at least one electrode 5 can be internally hollow so as to allow the insertion therein of a cooling system.

In a further embodiment, not shown in the Figures, the at least one electrode 5 can be internally hollow and it can have at least both a distal opening transversal to the main longitudinal development direction X of the bearer hollow member 1 and a side opening. Such embodiment allows directly injecting into the tissue an operative substance 17 through the at least one electrode 5.

It is pointed out that in any of the embodiments described above, the at least one electrode 5, in a section transversal to the main longitudinal development direction X of the bearer hollow member 1 , preferably comprises at least one substantially angle-shaped portion 9.

Alternatively, the at least one electrode 5, in a section transversal to the main longitudinal development direction X of the bearer hollow member 1 , has a substantially circular section.

Again, in further embodiments, the at least one electrode 5, in at least one first section transversal to the main longitudinal development direction X of the bearer hollow member 1 , has a geometric shape comprising at least one substantially angle-shaped portion 9. The at least one electrode 5, at least in a second section transversal to the main longitudinal development direction X of the bearer hollow member 1 , distinct from said first section, has a substantially circular section.

With reference to the example of Figs. 5a and 5b, an example of operation of an ablation device in accordance to the present invention is now described.

The free distal end 6 of said at least one electrode 5 is in the inactive position, i.e., completely within the bearer hollow member 1 (Fig. 5a). The free distal part 4 of the bearer hollow member 1 is then inserted by a medical operator in the patient, for example, in a tumor mass.

By acting on the mobile thrust joint 7 (Figs. 1a and 1b), the medical operator moves the free distal end 6 of the at least one active electrode 5 from the inactive position to the active position, through the distal opening 8 of the bearer hollow member 1 , so that the free distal end 6 takes the shape predefined by the construction in a shape memory material (for example, an arc of a circle shape).

After the at least one electrode 5 has been placed in the active position, an operative substance 17, for example a gel, to decrease the tissue resistivity and to promote the high-frequency treatment is diffused inside the tumor mass, by the at least one side opening 13 of the bearer hollow member 1.

The cooling system is then actuated, with circulation of the cooling substance 22 entering the first insertion cavity 20 and going out from the second evacuation cavity 21 of the thrust member 12, passing through the communication opening 19.

Finally, the radiofrequency generator is actuated.

The procedure ends when the amount of electromagnetic energy deemed sufficient to ablate the tumor mass has been supplied.

At the end of the treatment, the medical operator discontinues the electromagnetic energy supply and turns the cooling system off, and, by acting on the mobile thrust joint 7, withdraws the free distal end 6 of the active electrode 5 and withdraws the ablation device from the patient.

As it will be apparent, the described invention has a number of advantages. The main advantage are higher efficiency and repeatability compared to the ablation devices described with reference to the prior art. Indeed, the ablation device of the invention combines in an optimal manner both the effect of the active electrode and the effect of the operative substance.

This is due to the fact that the thrust member of the electrode allows the escape of the operative substance from the bearer hollow member of the ablation device. Furthermore, the free distal end of the electrode (or the electrodes) is so shaped as to intersect a plane (P1 or P2) orthogonal to the main longitudinal development direction of the bearer hollow member, when in an active position.

In this manner, the effect of the electric field generated by the electrode (or the electrodes) is combined with the effect generated by the operative substance, considerably decreasing the resistivity of the tissue to be ablated, hence, while keeping the supplied power constant, increasing the volume of ablated tissue.

Furthermore, where applied, the geometric configuration of an electrode comprising at least one substantially angle-shaped portion allows of sensibly increasing the active surface of the electrode, when compared to that of a cylindrical electrode. In fact, as it is easily verified by a mathematical calculation, the exposed surface of a threadlike electrode active of geometric shape in transversal section comprising at least one substantially angle-shaped portion, while keeping the length constant, is greatly larger than that of a threadlike electrode active with a cylindrical transversal section with the same gauge. It follows that, while keeping the gauge of the bearer hollow member and the length of the electrodes constant, it is possible to increase the active surface, or alternatively, while keeping the active surface of the electrodes constant, it is possible to reduce the gauge of the bearer hollow 5 member.

Another advantage associated to the configuration containing at least one substantially angle-shaped portion in the transversal geometric shape of the active electrode is that it advantageously allows increasing the directionality of the electrode, which hardly will rotate upon itself in the case l o that it meets a resistance in the tumor mass.

Again, the combination of such active electrodes to system using operative substances and cooling systems allows obtaining thermal lesions that could not be obtained with the systems described above.

Finally, multiple electrodes in accordance with the present invention is can be inserted inside a bearer hollow member without necessarily requiring a section increase thereof, and allowing obtaining also a better ablation directionality. This involves the obtainment of more reliable and performing ablation devices and with a reduced invasiveness.

To the above-described embodiments of the ablation device, those 0 of ordinary skill in the art, in order to meet contingent needs, will be able to make modifications, adaptations, and replacements of elements with other functionally equivalent ones, without departing from the scope of the following claims. Each of the characteristics described as belonging to a possible embodiment can be implemented independently from the other 5 embodiments described.

Claims

1. A high-frequency electromagnetic energy active ablation device (DDA), comprising:

a bearer hollow member (1) extending along a main longitudinal development direction (X), said bearer hollow member (1) being provided with an insulating outer coating (2), the bearer hollow member (1) comprising at least one opening (8, 13) arranged in the portion of a free distal part (4) lacking in the insulating outer coating (2),

at least one high-frequency active electrode (5), which is housed within the bearer hollow member (1), said at least one electrode (5) being configured to shift along the main longitudinal development direction (X) of the bearer hollow member (1) to bring a free distal end (6) of said at least one electrode (5) from an inactive position within the bearer hollow member (1) to an active position outside the bearer hollow member (1),

a thrust member (12) connected to a proximal end (16) of said at least one electrode (5), the proximal end of the thrust member (12) ending on a mobile thrust joint (7) of a handle (3) of the ablation device (DDA), said thrust member (12) being configured to shift along the main longitudinal development direction (X) of the bearer hollow member (1) to bring the free distal end (6) of said at least one electrode (5) from the inactive position inside the bearer hollow member (1) to the active position outside the bearer hollow member (1),

the ablation device (DDA) being characterized in that:

said thrust member (12) is configured to allow the escape of an operative substance (17) from said at least one opening (8, 13) of the bearer hollow member (1),

said at least one active electrode (5) being configured so that, when the free distal end (6) of the at least one electrode (5) is in the active position, the free distal end (6) intersects a plane (P1 , P2) orthogonal to the longitudinal development direction (X) of the bearer hollow member (1) passing through said at least one opening (8, 13).

2. An ablation device (DDA) according to claim 1 , wherein said at least one opening (8, 3) of the bearer hollow member (1) is at least one side opening (13), the thrust member (12) comprises a hollow cylinder with at least one side opening (14) at the distal end (15) thereof, to which the proximal end (16) of said at least one electrode (5) is secured, when the free distal end (6) of the at least one electrode (5) is in the active position, said at least one side opening (14) of the thrust member (12) and said at least one side opening (13) of the bearer hollow member (1) are mutually aligned, allowing the escape of the operative substance (17) injected into the thrust member (12).

3. An ablation device (DDA) according to claim 1 , wherein said at least one opening (8, 3) of the bearer hollow member (1) is a distal opening (8), the thrust member (12) comprises a hollow cylinder with at least one side opening (14) at the distal end (15) thereof to which the proximal end (16) of said at least one electrode (5) is secured, when the free distal end (6) of the at least one electrode (5) is in the active position, said at least one side opening (14) of the thrust member (12) is in a position along the main longitudinal development direction (X) of the bearer hollow member (1) such as to allow the escape of the operative substance (17) injected into the thrust member (12) from said distal opening (8).

4. An ablation device (DDA) according to claim 1 , wherein the thrust member (12) being piston-shaped, comprising a cylindrical base (23) transversal to the main longitudinal development direction (X) of the bearer hollow member (1) jointed to a development stem (24), which is parallel to the main longitudinal development direction (X) of the bearer hollow member (1), said cylindrical base (23) being configured so that, when the free distal end (6) of the at least one electrode (5) is in the active position, it is in a position along the main longitudinal development direction (X) of the bearer hollow member (1) such as to allow the escape from said at least one opening (8, 13) of the bearer hollow member (1) of the operative substance (17).

5. The device (1) according to claim 4, wherein said at least one opening (8, 13) of the bearer hollow member (1) is a distal opening (8).

6. The device (1) according to claim 4, wherein said at least one opening (8, 13) of the bearer hollow member (1) is at least one side opening (13).

7. The device (1) according to claim 4, wherein said at least one opening (8, 13) of the bearer hollow member (1) is both the distal opening (8) and at least one side opening (13).

8. The ablation device (DDA) according to claim 1 , wherein the thrust member (12) is piston-shaped, comprising a cylindrical base (23) transversal to the main longitudinal development direction (X) of the bearer hollow member (1) jointed to a development hollow cylinder (25), which is parallel to the main longitudinal development direction (X) of the bearer hollow member (1 ), said cylindrical base (23) being configured so that, when the free distal end (6) of the at least one electrode (5) is in the active position, it is in a position along the main longitudinal development direction (X) of the bearer hollow member (1) such as to allow the escape from said at least one opening (8, 13) of the bearer hollow member (1) of an operative substance (17), said hollow cylinder (25) comprising a partition wall (18) parallel to the main longitudinal development direction (X) of the bearer hollow member (1) adapted to define a first insertion cavity (20) and a second evacuation cavity (21) of a cooling substance (22), said partition wall (18) being adapted to end in the proximity of the distal end (15) of the thrust member (12) to define a communication opening (19) between the first insertion cavity (20) and the second evacuation cavity (21), the cooling substance (22) being suitable to pass from the first insertion cavity (21) to the second evacuation cavity (21) by passing through said communication opening ( 9).

9. The device (1) according to claim 8, wherein said at least one opening (8, 3) of the bearer hollow member (1) is a distal opening (8).

10. The device (1) according to claim 8, wherein said at least one opening (8, 13) of the bearer hollow member (1 ) is a side opening (13).

11. The device (1) according to claim 8, wherein said at least one opening (8, 13) of the bearer hollow member (1) is both the distal opening (8) and at least one side opening (13).

12. The ablation device (DDA) according to any of the preceding claims, wherein said at least one electrode (5), in a section transversal to the main longitudinal development direction (X) of the bearer hollow member (1), has a geometric shape comprising at least one substantially angle-shaped portion (9, 9').

13. The ablation device (DDA) according to any of the dependent claims 1 to 11 , wherein said at least one electrode 5, in a section transversal to the main longitudinal development direction (X) of the bearer hollow member (1), has a substantially circular section.

14. The ablation device (DDA) according to any of the dependent claims 1 to 11 , wherein said at least one electrode (5), in at least one first section transversal to the main longitudinal development direction (X) of the bearer hollow member (1), ^' has a geometric shape comprising at least one substantially angle-shaped portion (9), said at least one electrode (5), at least in a second section transversal to the main longitudinal development direction (X) of the bearer hollow member (1), distinct from said first section, has a substantially circular section.