WO2025146252A1

WO2025146252A1 - A catheter for venous ablation

Info

Publication number: WO2025146252A1
Application number: PCT/EP2024/050200
Authority: WO
Inventors: Seán WALL
Original assignee: ClearStream Technologies Ltd
Current assignee: ClearStream Technologies Ltd
Priority date: 2024-01-05
Filing date: 2024-01-05
Publication date: 2025-07-10
Anticipated expiration: 2026-07-05

Abstract

A catheter for venous ablation which comprises a catheter body having a longitudinal axis. The catheter further comprises a first electrode disposed at least partially within the catheter body and having a distal portion, an intermediate portion and a proximal portion. The first electrode is reversibly transitionable from a radially contracted configuration to a radially expanded configuration. In the radially expanded configuration, the intermediate portion is configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel.

Description

A Catheter for Venous Ablation

Technical Field

The present disclosure relates to a catheter for venous ablation and a venous ablation system.

Background

Superficial venous reflux and chronic venous insufficiency occur when veins fail to return blood to the heart properly. Both superficial venous reflux and chronic venous insufficiency may present as varicose veins, particularly in the lower limbs. Varicose veins can cause pain and fatigue in the affected area and in severe cases may cause poor blood circulation in an affected limb.

These conditions may be treated by ablation of the affected vessels. Ablation of a vessel (e.g., a vein) , also referred to as "venous ablation" herein, refers to the shutting down or closing off of varicose veins such that blood no longer flows through the vessel. Such treatment requires destruction or damage, i.e., ablating, of the affected vessel that is sufficient to provoke an inflammatory response that results in the vessel shutting down.

Conventionally, this is achieved by thermal ablation of the affected vessel. Such procedures typically require insertion of a catheter into the affected vessel, which is used to apply heat energy, e.g., radiofrequency (RF) or laser energy to the vessel. The heat energy causes the vessel to collapse as the catheter is removed.

However, such conventional thermal ablation procedures tend to cause significant patient pain due to the high temperatures required. As such, thermal ablation procedures also generally require tumescent anaesthesia, in which relatively large volumes of dilute local anaesthetic solution are delivered to the target tissue, rendering the target tissue firm and turgid. Furthermore, conventional thermal ablation has lengthy procedure times and is costly.

There are currently non-thermal ablation options available. These generally involve the use of implanted materials like sclerosants (STS, Asclera®, Varithena® etc.) or cyanoacrylate adhesives (e.g., VenaSeal®) , alone or in combination with mechanical ablation-based treatments, to shut down affected vessels. Such combined approaches are known as mechanicochemical ablation (MOCA) devices.

However, such existing non-thermal ablation options require material to be implanted in the patient, which may not be preferable .

In view of the above, there is a need for an improved way provoking an inflammatory response of a vessel in order to shut down or close off the vessel that reduces patient pain and that does not require use of an implanted material. Preferably such an improved way of performing venous ablation is non-tumescent (i.e., not requiring the use of tumescent anaesthetic) .

There is further a need in the art for an improved way of performing venous ablation which reduces the treatment time and number of steps.

Summary

In a first aspect of the present disclosure, there is provided a catheter for venous ablation. The catheter comprises a catheter body having a longitudinal axis. The catheter further comprises a first electrode disposed at least partially within the catheter body and having a distal portion, an intermediate portion and a proximal portion . The first electrode is reversibly transitionable from a radially contracted configuration to a radially expanded configuration . In the radially expanded configuration, the intermediate portion is configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel .

Throughout this disclosure , the terms "proximal" and "distal" refer to the proximal and distal directions in relation to the catheter, unless otherwise speci fied . In that case , "proximal" refers to a point on the catheter which is intended to be closer to a physician when the catheter is in use , while "distal" refers to a point on the catheter which is intended to be further away from a physician when the catheter is in use .

Throughout this disclosure , the " longitudinal axis" of the catheter refers to the axis of the catheter that extends in the proximal and distal directions in relation to the catheter . The catheter may not have a fixed longitudinal extent relative to the longitudinal axis , but rather a flexible configuration that allows the catheter to navigate the vessel .

Throughout this description, the "radially expanded configuration" of an element refers to a configuration where the element extends radially further from the catheter body than in the "radially contracted configuration" .

Throughout this description, the "radially contracted configuration" of an element refers to a configuration where the element extends radially less from the catheter body than in the "radially expanded configuration" . Optionally, in some embodiments , an element may be contained within the radial extent of the catheter body in its radially contracted configuration.

Throughout this disclosure, the term "ablate" or "ablating" refers to at least partially destroying or damaging a target tissue, e.g., so as to provoke or contribute to provoking an inflammatory response. Throughout this disclosure, the term "venous ablation" refers more generally to the overall process of destroying or damaging (i.e., ablating) a target tissue in a vessel so as to provoke or contribute to provoking an inflammatory response that in turn causes the vessel to shut down.

In embodiments, at least an endothelial layer of the vessel is ablated. In some embodiments, a medial layer of the wall of the vessel may also be at least partially ablated, i.e., at least partially destroyed or damaged, by the operation of the catheter.

Throughout this disclosure, the term "contact a wall of a vessel" refers to at least a part of the intermediate portion of the first electrode (e.g., a surface of the intermediate portion or an element attached thereto) making direct physical contact with, i.e., touching, the wall of the vessel.

Throughout this disclosure, the vessel may be, for example, a vein.

In some embodiments, the catheter according to the first aspect may result in an improved means of venous ablation.

In particular, as the intermediate portion of the first electrode may be brought into contact with the vessel wall when the first electrode is in its radially expanded configuration, energy may be applied directly to the wall of the vessel where it contacts the intermediate portion. The application of energy directly to the wall of the vessel in this manner may at least partially destroy or damage at least the endothelial layer of the vessel wall , thereby causing suf ficient irritation to provoke an inflammatory response . Such an inf lammatory response may in turn prompt the vessel to shut down as the catheter is removed, thereby achieving venous ablation .

This direct contact may result in less energy being required in order to ablate at least the endothelial layer of the vessel wall suf ficiently to provoke an inflammatory response . In particular, less energy may be required relative to conventional thermal ablation systems which rely on heat energy and, as such, relatively high temperatures , to shrink and close the vessel .

Reducing the amount of energy to be applied for venous ablation may allow for lower treatment temperatures and/or reduced treatment times . This may, in turn, result in les s pain for the patient undergoing treatment and/or a more energy ef ficient procedure .

Reducing the amount of energy to be applied for venous ablation may also allow for smaller wire si zes ( e . g . , from 0 . 004" / 0 . 1016mm to 0 . 012" / 0 . 3048mm flat cross section or round diameter ) or other such components to be used for the first electrode as the first electrode may only need to withstand relatively low current values .

In some embodiments , this may in turn allow the profile of the catheter to be reduced for easier movement through a vessel .

Furthermore , the catheter according to the first aspect described herein may allow venous ablation to be achieved without requiring materials such as sclerosants or cyanoacrylate adhesives to be implanted in the patient . In addition, the first electrode has a radially contracted configuration . The first electrode may be in its radially contracted configuration when it is not being used to ablate the wall of the vessel , e . g . , when the catheter is being delivered to or otherwise moved through the vessel .

In some embodiments , this may allow the profile of the catheter to be reduced for easier movement through a vessel . This may, in turn, result in a catheter which can more easily navigate tortuous vessel anatomy .

The first electrode may be a leaf spring .

In some embodiments , this may allow the first electrode to be bent and flexed without breaking .

Throughout this disclosure , the term " leaf spring" will be used to refer to a flexible curved strip of material or a flexible curved wire which can be deformed but will regain its original shape when released .

The first electrode may have a convex portion .

In some embodiments , this may allow the first electrode to be easily bent or flexed to increase the height of the first electrode . Throughout this disclosure , the height o f the electrode refers to the extent or amount by which the electrode extends beyond the catheter body in a radial direction, unless explicitly indicated otherwise .

This may in turn allow the intermediate portion to be readily brought in contact with the wall of the vessel , resulting in good ablation of the vessel .

The first electrode may be a ribbon wire . In some embodiments , this may provide a larger surface to contact the vessel wall compared to , e . g . , a single wire , thereby resulting in improved application of energy to the vessel wall and, as such, good ablation of the vessel .

The first electrode may comprise at least one ablating structure for ablating at least the endothelial layer o f the vessel .

Throughout this disclosure , the term "ablating structure" may refer to any structure , unit or device configured to mechanically ( i . e . , physically) damage or destroy a target tissue at least partially, such as by scratching, scoring, abrading, denuding, etc .

The at least one ablating structure may comprise one or more wire hooks and/or teeth .

Throughout this disclosure , the at least one ablating structure may also be referred to as barbs or protrusions .

The wire hooks may be formed of a ribbon wire or a round wire .

The at least one ablating structure may comprise at least one serrated or barbed edge .

The serrated or barbed edge may be disposed on a radially outer surface of the first electrode or on a radially outer surface of the one or more wire hooks and/or teeth .

Throughout this disclosure , the term "radially outer surface" is used to denote a radial outer side of a component of the catheter that faces the vessel wall when the catheter is inserted in the vessel . The at least one ablating structure may comprise an abrasive surface , e . g . , on a radially outer surface of the first electrode .

Throughout this disclosure , the term "abrasive surface" i s used to denote a roughened surface that can scrape away tissue through friction .

In some embodiments , the inclusion of at least one ablating structure may allow venous ablation to be achieved by a combination of application of energy via the first electrode and mechanical irritation of the vessel wall . This may in turn allow the amount of energy required in order to ablate at least the endothelial layer of the vessel wall suf ficiently to provoke an inflammatory response for shutting down the vessel to be further reduced .

The at least one ablating structure is provided on the intermediate portion .

In some embodiments , this may allow the at least one ablating structure to be brought in close contact with the wall of the vessel when the first electrode is in its radially expanded configuration and thus result in better venous ablation .

In some embodiments , this may allow the at least one ablating structure to be brought closer to an outer surface of the catheter body, e . g . , at least partially disposed in the catheter body, when the first electrode is in its radially contracted form . Thi s may in turn allow maintaining a reduced profile of the catheter, even where at least one ablating structure is included .

The catheter may further comprise a cover configured to cover the first electrode when the first electrode is in the radially contracted configuration . For example , the cover may be a sheath .

The first electrode may be transitionable from the radially contracted configuration to the radially expanded configuration by removal of the cover .

By way of example , the first electrode may be configured such that , in the absence of external biasing forces , the first electrode is in its radially expanded configuration . The cover may serve to press or otherwise force the first electrode into its radially contracted configuration . As such, the removal of the cover causes the first electrode to transition to its radially expanded configuration .

This transition may be reversible by replacement of the cover, e . g . , by operation of a suitable configured handle or push wire , such as for extraction of the catheter from the vessel .

In some embodiments , this may reduce the number of catheter components and simpli fy the mechanism of controlling the transition of the first electrode from the radially contracted configuration to the radially expanded configuration .

The catheter may be part of an assembly comprising a handle .

The first electrode may be reversibly transitionable from the radially contracted configuration to the radially expanded configuration by operation of the handle .

In some embodiments , this may provide a simpler way to control transition of the first electrode between the radially contracted and radially expanded configurations . In embodiments in which the catheter comprises a cover configured to cover the first electrode when the first electrode is in the radially contracted configuration, the handle may comprise a sheath sliding control .

The sheath sliding control may comprise a slider for moving the sheath in a proximal or distal direction to unsheathe or sheathe the first electrode , respectively, and to thereby change the configuration of the first electrode from the radially contracted conf iguration to the radially expanded configuration and vice versa .

Alternatively, sheath sliding control may comprise a linear actuator such as a rack and pinion or any other suitable mechanism which can move the sheath longitudinally .

The handle may comprise a push wire that is connected to a proximal end of the first electrode .

The handle may comprise a switch configured to control provision of power to the first electrode .

In some embodiments , this may provide a simpler way to control the operation of the catheter to perform venous ablation .

The first electrode may have a first radially expanded configuration and a second radially expanded configuration .

The intermediate portion may extend radially from the catheter body by a first amount in the first radially expanded configuration . The intermediate portion may extend radially from the catheter body by a second amount in the second radially expanded configuration, the second amount being di f ferent from the first amount . In some embodiments , the first electrode may have a plurality of radially expanded configurations , e . g . two or more radially expanded configurations .

The intermediate portion may extend radially from the catheter body by a di f ferent respective amount in each radially expanded configuration .

The plurality of radially expanded configurations may correspond to discrete respective radial positions of the first electrode relative to the catheter body or a continuous range of radial positions of the first electrode relative to the catheter body .

In some embodiments , this may result in a catheter where the height of the first electrode can be adj usted in a more ef fective and flexible manner . This in turn may allow the catheter to be more conveniently used for treating varicose veins of a wider range of si zes .

In embodiments in which the catheter comprises a handle , the handle may be operable to control the extent of radial expansion of the first electrode .

In some embodiments , this may allow better control of the expansion of the first electrode .

The catheter may further comprise a plurality of electrodes including the first electrode .

In some embodiments this may result in better venous ablation because the wall of the vessel may be at multiple di f ferent locations along the vessel simultaneously or at least reducing the need for the catheter to be repositioned within the vessel during the treatment . The above description of the first electrode applies mutatis mutandis to each of the plurality of electrodes .

In particular, each of the plurality of electrodes may have a distal portion, an intermediate portion and a proximal portion . Each of the plurality of electrodes may be reversibility transitionable from a radially contracted configuration to a radially expanded configuration .

For each of the plurality of electrodes , in the radially expanded configuration, the intermediate portion of that electrode may be configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel .

The first electrode of the plurality of electrodes may extend radially from the catheter body in a di f ferent respective direction to a second electrode of the plurality of electrodes .

In some embodiments , each of the plurality of electrodes may extend radially from the catheter body in a di f ferent respective direction .

In some embodiments this may allow the wall of the vessel to be ablated in multiple di f ferent directions simultaneously or at least without requiring the catheter to be rotated or turned within the vessel during the treatment .

In some embodiments , this may in turn result in better venous ablation and a further reducing of the treatment times .

The catheter body may comprise a f irst section and a second section along the longitudinal axi s . By way of example , the catheter body may comprise a plurality of sections (e.g., two or more sections) along the longitudinal axis.

In some embodiments, this may result in a catheter which can more easily navigate tortuous vessel anatomy.

The first section may comprise one or more electrodes of the plurality of electrodes and the second section may comprise a different one or more electrodes of the plurality of electrodes.

By way of example, in some embodiments, each section of the plurality of sections may comprise two or more of the plurality of electrodes.

In some embodiments, this may allow the wall of the vessel to be ablated at multiple different locations along the vessel simultaneously or at least reducing the need for the catheter to be repositioned within the vessel during the treatment .

In some embodiments, this may in turn result in better venous ablation and a further reducing of the treatment times .

Successive sections among the plurality of sections of the catheter body may be connected via at least one flexible connection element.

In some embodiments, this may result in a more stable configuration of the catheter.

The at least one flexible connection element may comprise a catheter sleeve, a ribbon, a wire, a microspring, a ball and socket joint, or a connecting rod. Each of the plurality of electrodes may comprise at least one ablating structure for ablating at least the venous endothelium .

The respective at least one ablating structure may be provided on the intermediate portion of each of the plurality of electrodes .

The at least one ablating structure of each of the plurality of electrodes may be configured as discussed above in relation to the at least one ablating structure of the first electrode .

The catheter body may comprise a housing for housing the first electrode .

In some embodiments , this may result in a more stable configuration of the catheter .

The housing may be a ceramic housing .

In some embodiments , this may result in a housing which can better withstand the current and heat generated by the first electrode .

The housing may have a proximal section and a distal section, the first electrode being disposed at least partially within the housing .

The distal portion of the first electrode may be connected to the distal section of the hous ing, the proximal portion of the first electrode connected to the proximal section of the housing .

The proximal housing section and the distal housing section may be longitudinally moveable with respect to each other to transition the first electrode from the radially expanded configuration to the radially contracted configuration and vice versa .

The proximal housing section and the distal housing section may be connected via at least one flexible connection element .

In some embodiments , this may result in a more stable configuration of the first catheter .

The at least one flexible connection element may comprise a catheter sleeve .

In some embodiments , this may result in a more stable configuration of the housing while still maintaining flexibility of the catheter .

The catheter sleeve may be disposed around at least the proximal and distal sections of the housing .

The housing may comprise an opening . The first electrode may extend out of the opening .

The catheter sleeve may comprise an opening . The opening of the catheter sleeve may be aligned with the opening of the housing .

The at least one flexible connection element may comprise a ribbon, wire or microspring .

In some embodiments , this may result in a more stable configuration of the housing while still maintaining flexibility of the catheter . The ribbon, wire or microspring may be insulated .

In some embodiments , this may prevent arcing between the first electrode and the ribbon, wire or microspring .

The ribbon, wire or microspring may be fixed to one of the housing sections and longitudinal ly moveable with respect to the other housing section .

In some embodiments , this may make it easier for a user to move the proximal and distal housing sections with respect to each other to adj ust the height of the first electrode .

The ribbon, wire or microspring may be fixed to the proximal housing section and longitudinally moveable with respect to the distal housing section .

In some embodiments , this may allow a user to easily manipulate the height of the first electrode by pushing or pulling the proximal section of the housing .

A pull wire may be connected to the distal housing section to allow the distal housing section to be moved longitudinally with respect to the proximal housing section .

In some embodiments , this may allow a user to easily manipulate the height of the electrode .

The first electrode may be configured to not ablate tissue outside the vessel .

For example , an amount by which the first electrode extends from the catheter body in the radially expanded configuration may be configured such that the first electrode does not ablate tissue outside the vessel . Additionally or alternatively, an amount of the energy applied by the first electrode to the vessel wall may be configured such that the first electrode does not ablate tissue outside the vessel .

That is , at least one of the amount by which the first electrode extends from the catheter body in the radially expanded configuration and the amount of the energy applied by the first electrode to the vessel wall may be suf ficient to allow one or more layers of the vessel , including the endothelial layer, to ablated . However, these amounts may be set to minimi ze or avoid ablating an outermost layer of the vessel wall and/or tissue surrounding the vessel . E . g . , the amount by which the first electrode extends from the catheter body in the radially expanded configuration may be configured to allow the intermediate portion to touch the vessel wall while minimi zing any outward pressure exerted by the intermediate portion on the vessel wall and/or applied energy may be supplied at a low power such that plasma is not generated by the first electrode .

In some embodiments , such a configuration may be distinguished from an electrode used to form a fistula between two vessels . A fistula denotes a passageway formed between two internal organs and, by necessity, formation of a fistula requires removal of tissue between those two internal organs .

In a second aspect of the present disclosure , there is provided a venous ablation system . The venous ablation system comprises a catheter in accordance with the first aspect of the present disclosure . The venous ablation system further comprises a radiofrequency generator for supplying radiofrequency energy to the first electrode . The radiofrequency generator may be configured to supply radiofrequency energy at a low power such that plasma is not generated by the first electrode .

In some embodiments , the radiofrequency generator may be configured to supply radiofrequency energy having a frequency of one or both of : at least 100Hz and/or less than 100GHz . Alternatively, or additionally, the radiofrequency generator may be configured to supply radiofrequency energy having a power of one or both of : at least 0 . 01W and/or less than 100W, either fully or partially dispersed about the electrodes .

The generation of plasma requires a radiofrequency energy to be supplied at a relatively high power . The plasma causes rapid dissociation of molecular bonds in the organic compounds and allows to readily cut through vessel walls . While such an approach may be use ful in forming a fistula, this may be excessive for the purpose of venous ablation .

In some embodiments , supplying radiofrequency energy at a low power such that plasma is not generated by the first electrode may allow at least the endothelial layer to be ablated, thereby enabling venous ablation, while minimi zing the risk of damage to the tissue surrounding the vessel .

This may also result in less energy being required in order to ablate at least the endothelial layer of the vessel wall suf ficiently to provoke an inflammatory response for shutting down the vessel .

This may, in turn, result in less pain for the patient undergoing treatment and/or a more energy ef ficient procedure .

According to a third aspect of the present disclosure , there is provided a method of performing venous ablation . The method comprises positioning a first electrode at a treatment site in a vessel while the first electrode is in a radially contracted configuration . The further method comprises contacting a wall of the vessel with at least an intermediate portion of the first electrode by transitioning the first electrode from the radially contracted configuration to a radially expanded configuration . The method further comprises ablating at least an endothelial layer of the vessel by supplying RF energy to the electrode and applying the RF energy to the wall of the vessel via the intermediate portion .

In some embodiments , the method according to the third aspect may result in an improved way of performing venous ablation .

In particular, as the vessel wall is contacted by the intermediate portion of the first electrode , energy may be applied directly to the wall of the vessel where it contacts the intermediate portion . The application of energy directly to the wall of the vessel in this manner may at least partially destroy or damage at least the endothelial layer of the vessel wall , thereby causing suf ficient irritation to provoke an inflammatory response . Such an inflammatory response may in turn prompt the vessel to shut down as the catheter is removed, thereby achieving venous ablation .

This direct contact may result in less energy being required in order to ablate at least the endothelial layer of the vessel wall suf ficiently to provoke an inflammatory response . In particular, less energy may be required relative to conventional thermal ablation systems which rely on heat energy and, as such, relatively high temperatures , to shrink and close the vessel . Similar to the first aspect , reducing the amount of energy to be applied for venous ablation may allow for lower treatment temperatures and/or reduced treatment times . This may, in turn, result in less pain for the patient undergoing treatment and/or a more energy ef ficient procedure .

Contacting the wall of the vessel with at least the intermediate portion of the first electrode may comprise controlling an amount by which the intermediate portion extends radially in the radially expanded configuration in accordance with a si ze of the vessel .

In some embodiments , this may allow the height of the first electrode to be adj usted in a more ef fective and flexible manner, thereby enabling treatment of varicose veins of a wider range of si zes .

Furthermore , the amount by which the first electrode radially extends in the radially expanded configuration may be set such that it is suf ficient to allow one or more layers of the vessel , including the endothelial layer, to ablated but minimi zes or avoids ablating an outermost layer of the vessel wall and/or tissue surrounding the vessel . E . g . , the amount by which the first electrode radially extends may be controlled to allow the intermediate portion to touch the vessel wall while minimi zing any outward pressure exerted by the intermediate portion on the vessel wall .

Ablating at least the endothelial layer of the vessel may further comprise controlling an amount of the RF energy applied to the wall of the ves sel such that the first electrode does not ablate tissue outside the vessel .

That is , the amount of RF energy applied by the first electrode to the vessel wall may be suf ficient to allow one or more layers of the vessel , including the endothelial layer, to ablated but minimi zes or avoids ablating an outermost layer of the vessel wall and/or tissue surrounding the vessel . E . g . , the amount of applied energy may be supplied at a low power such that plasma is not generated by the first electrode .

Positioning the first electrode at the treatment site may comprise inserting a catheter, comprising the first electrode , into the vessel through an access site .

The method performed using a catheter according to the first aspect herein .

Brief Description of the Drawings

To enable better understanding of the present disclosure , and to show how the same may be carried into ef fect , reference will now be made , by way of example only, to the accompanying drawings , in which :

FIG . 1 shows a catheter for venous ablation, according to one or more embodiments shown and described herein .

FIG . 2A shows a side view of a catheter in a radially contracted configuration, according to one or more embodiments shown and described herein .

FIG . 2B shows a side view of the catheter of FIG . 2A in a radially expanded configuration .

FIG . 3 shows a side view of an alternative embodiment of a catheter in a radially expanded configuration, according to one or more embodiments shown and described herein . FIG . 4 shows a perspective view of an alternative embodiment of a catheter in a radially expanded configuration, according to one or more embodiments shown and described herein .

FIG . 5 shows a section view and a side view of an alternative embodiment of a catheter in a radially contracted configuration, according to one or more embodiments shown and described herein .

FIG . 6A shows a catheter, according to one or more embodiments shown and described herein, disposed in a venous system .

FIG . 6B shows the venous system following venous ablation treatment using the catheter as shown in FIG . 6A.

FIG . 7 is a schematic diagram il lustrating a process for performing venous ablation using the catheter of any of FIG . s 1 to 6A, according to one or more embodiments shown and described herein .

Detailed Description

The body of the catheter 100 comprises a catheter shaft 110 and a housing 120 disposed at the distal end of the shaft 110 . The housing 120 has an opening and a first electrode 130 , which is partially disposed in the housing 120 and extends out of the opening . The housing 120 is made from a non-conductive ceramic material which can withstand the current and heat generated by the first electrode 130 .

The catheter 100 further comprises a cover 115 , e . g . , in the form of a sheath in the present example , configured to cover the first electrode 130 when the first electrode 130 is in the radially contracted configuration . The first electrode 130 may be reversibly transitionable from the radially contracted configuration to the radially expanded configuration shown in FIG . 1 by removal of the cover 115 . Removal of the cover 115 may be achieved by, e . g . , a handle , a pull wire or any other suitable means disclosed herein .

In order to perform a venous ablation, the catheter 100 is introduced into the venous system through an access site and advanced to the treatment site , namely the vessel to undergo ablation . During this process , the first electrode 130 is maintained in is radially contracted configuration .

Once the catheter 100 has been appropriately positioned in the venous system, the first electrode 130 is transitioned to its radially expanded configuration so as to bring the intermediate portion of the first electrode into contact with the wall of the vessel .

Energy, e . g . , radiofrequency (RF) energy, is then supplied to the first electrode 130 which applies the energy directly to the wall of the vessel where it contacts the intermediate portion in order to ablate at least the endothelial layer of the vessel wall suf ficiently to provoke an inflammatory response . Such an inflammatory response may in turn prompt the vessel to shut down as the catheter 100 is removed, thereby achieving venous ablation .

FIG . 2A shows a side view of a catheter 100 in a radially contracted configuration, according to one or more embodiments shown and described herein . The body of the catheter 100 of FIG . 2 comprises a catheter shaft 110 and a housing 120 disposed at the distal end of the catheter shaft 110 . The housing 120 is split into a proximal housing section 121 and a distal housing section 122 and has a lateral opening 123 . A first electrode 130 is disposed partially within the housing 120 . The first electrode 130 may be a leaf spring, which may have a proximal portion 131 which is fixed to the proximal housing section 121 and a distal portion 132 which is fixed to the distal housing section 132 .

The distal portion 132 is shown in FIG . 2A as being fixed to the distal housing section 122 with an adhesive , but may also be fixed with a clamp mechanism, for example . The proximal portion 131 is shown as being fixed to the proximal housing section 121 with a clamp mechanism, but may also be fixed with an adhesive , for example . By way of further alternative , the distal portion 132 of the electrode 130 may not be fixed to the distal housing portion 122 , but may be allowed some room for movement while still allowing the electrode 130 to transition from the radially contracted configuration to radially expanded configuration and vice versa .

An intermediate portion 133 of the first electrode 130 is positioned between the proximal and the distal portion 131 , 132 and extends out of the opening 123 for contacting the vessel wall when the first electrode 130 is in its radially expanded configuration to perform venous ablation . The intermediate portion 133 may have a convex shape which extends away from the housing 120 . The distance between the top of the intermediate portion 133 and the housing 120 is the height H of the electrode 130 .

The first electrode 130 may be in the form of a ribbon wire and may be made from a number of suitable materials , such as one or more refractory metals . For example , the first electrode 130 may comprise tungsten, molybdenum, niobium, tantalum, rhenium, or combinations and alloys thereof . The housing 120 may be made from a non-conductive ceramic material which can withstand the heat and current generated by the first electrode 130 .

A connecting element 134 may be connected to the proximal portion 131 of the first electrode and extends along the length of the catheter shaft 110 . The proximal end of the connecting element 134 may then be connected to an energy supply (not shown) , for example in the form of an electrosurgical (ESU) unit , for supplying the electrode 130 with energy .

The proximal and distal housing sections 121 , 122 are moveable relative to each other . FIG . 2 shows the first catheter 100 with the first electrode 130 in a radially contracted configuration where the height H of the first electrode 130 is smaller than in its radially expanded configuration . In the radially contracted configuration, the proximal housing section 121 and the distal housing section 122 are not in contact and are separated by a distance D . The proximal and distal housing sections 121 , 122 can be moved closer together to reduce the distance D and thereby increase the height H of the electrode .

In the radially contracted configuration of FIG . 2 , the catheter 100 has a smaller radial extent and a lower profile . This means that the catheter 100 can be more easily introduced into and advanced through a blood vessel . I f a cover ( such as sheath 115 shown in FIG . 1 ) is used to introduce the catheter 100 into a vessel , the radially contracted configuration allows the catheter 100 to more easily fit into the cover .

The catheter 100 may further comprise a catheter sleeve 150 which is disposed around the proximal and distal housing sections 121 , 122 and may extend along the length of the catheter shaft 110 . The catheter sleeve 150 is a flexible connection element for connecting the proximal and distal housing sections 121 , 122 and provides stability to the split housing 120 . The catheter sleeve comprises an opening which aligns with opening 123 of the housing to allow the first electrode 130 to extend out of the housing 120 . The catheter sleeve 150 may be flexible to allow the proximal and distal housing sections 121 , 122 to move relative to each other . Alternatively, the proximal housing section 121 or the distal housing section 122 may be slidably moveable within the catheter sleeve 150 .

FIG . 2B shows a side view of the catheter of FIG . 2A in a radially expanded configuration where the first electrode 130 has a greater height H than in the radially contracted configuration .

In order to transition the first electrode 130 from the radially contracted configuration to the radially expanded configuration, a user can push the proximal housing section 121 in a distal direction . This can be done while the first catheter 100 is inside a vessel . The position of the distal section 122 of the housing may be fixed within the structure of the catheter 100 .

When the user pushes the proximal housing section 121 distally, this causes the distance D between the proximal and distal housing sections 121 , 122 to be reduced and thereby increases the height H of the first electrode 130 . FIG . 2B shows the distance D between the two housing sections 121 , 122 in the radially expanded configuration to be smaller than in the radially contracted configuration but non- zero , such that the two housing sections 121 , 122 do not contact each other .

However, the first catheter 100 may also be configured to have the proximal and distal housing sections 121 , 122 touching in the radially expanded configuration . A handle may be connected at the proximal end of the first catheter shaft 110 and assist a user in pushing the proximal housing section 121 distally to increase the electrode height H .

The increased electrode height H allows the intermediate portion 133 of the first electrode 13 , in its radially expanded configuration, to contact the wall of the vessel so that energy may be applied to the wall of the vessel in order to ablate at least the endothelial layer of the wall of the vessel .

FIG . 3 shows a side view of an alternative embodiment of a catheter 100 in a radially expanded configuration, according to one or more embodiments shown and described herein .

The catheter 100 of FIG . 3 is similar to the catheter 100 of FIG . 1 and of FIG . s 2A and 2B, and the same reference numerals are used to denote features that are identical unless explicitly stated otherwise .

The body of the catheter 100 of FIG . 3 comprises a catheter shaft 110 and a housing 120 disposed at the distal end of the shaft 110 . The housing 120 has a plurality of openings and a corresponding plurality of electrodes , comprising a first electrode 130A and a second electrode 130B . Each of the plurality of electrodes is partially disposed in the housing 120 and extends out of a respective opening .

Each of the first electrode 130A and the second electrode 130B has a distal portion, an intermediate portion and a proximal portion . For each of the first electrode 130A and the second electrode 130B, in the radially expanded configuration, the intermediate portion of that electrode is configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel .

The catheter 100 may also comprise a ceramic spacer 160 positioned between the first electrode 130A and the second electrode 130B within the housing 120 for electrically isolating the first electrode 130A from the second electrode 130B .

Each of the first electrode 130A and the second electrode 130B comprise at least one ablating structurel 35A, 135B for ablating the venous endothelium provided . The at least one ablating structure 135A, 135B is provided on the respective intermediate portion of the respective electrode .

The at least one ablating structure 135A, 135B of the first and second electrodes 130A, 130B are each in the form of a one or more wire hooks , speci fically five wire hooks as shown in the example of FIG . 3 . The wire hooks 135A, 135B may be formed of a ribbon wire or a round wire .

The first electrode 130A and the second electrode 130B each extend radially from the catheter body in a di f ferent respective direction . This allows the wall of the vessel to be ablated in multiple di f ferent directions simultaneously or at least without requiring the catheter 100 to be rotated or turned within the vessel during the treatment .

Although not shown, the first electrode 130A and the second electrode 130B may be respectively movable from the radially contracted configuration to the radially expanded configuration by removal of a cover, as disclosed in relation to FIG . 1 .

FIG . 4 shows a perspective view of an alternative embodiment of a catheter in a radially expanded configuration, according to one or more embodiments shown and described herein .

The catheter 100 of FIG . 4 is similar to the catheter 100 of FIG . s 1 to 3 , and the same reference numerals are used to denote features that are identical unless explicitly stated otherwise .

The body of the catheter 100 of FIG . 4 comprises a catheter shaft 110 and a plurality of sections , each section comprising a respective housing 120A, 120B, 120C, disposed successively at the distal end of the shaft 110 . Each housing 120A, 120B, 120C has a respective opening and a respective electrode 130A, 130B, 130C . Each of the plurality of electrodes 130A, 130B, 130C is partially disposed in the respective housing 120 and extends out of a respective opening .

For each of the plurality of electrodes 130A, 130B, 130C, in the radially expanded configuration, the intermediate portion of that electrode is configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel . This may allow the wall of the vessel to be ablated at multiple di f ferent locations along the vessel simultaneously or at least reducing the need for the catheter 100 to be repositioned within the vessel during the treatment .

Although not shown, successive sections among the plurality of sections 120A, 120B, 120C of the catheter body may be connected via at least one flexible connection element . That is , section 120A and section 120B of the catheter body may be connected via at least one flexible connection element and section 120B and section 120C of the catheter body may be connected via at least one flexible connection element . This may, in turn, result in a more flexible catheter, which can more easily navigate tortuous vessel anatomy .

The plurality of electrodes 130A, 130B, 130VC may be respectively transitionable from the radially contracted configuration to the radially expanded configuration by removal of the cover 115 , in a similar manner as disclosed in relation to FIG . 1 .

FIG . 5 shows a section view and a side view of an alternative embodiment of a catheter 100 in a radially contracted configuration, according to one or more embodiments shown and described herein .

The catheter 100 of FIG . 5 is similar to the catheter 100 of FIG . s 1 to 4 , and the same reference numerals are used to denote features that are identical unless explicitly stated otherwise .

The body of the catheter 100 of FIG . 5 comprises a housing 120 , which may be disposed at a distal end of a catheter shaft as described in relation to FIG . s 1 to 4 . The housing 120 has a plurality of openings and a corresponding plurality of electrodes 130A- 130F . Each of the plurality of electrodes 130A- 130F is partially disposed in the housing 120 and extends out of a respective opening .

Each of the plurality of electrodes 130A- 130F has a distal portion, an intermediate portion and a proximal portion . For each of the plurality of electrodes 130A- 130F, in the radially expanded configuration, the intermediate portion of that electrode is configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel . The plurality of electrodes 130A- 130F each extend radially from the catheter body in a di f ferent respective direction . This allows the wall of the vessel to be ablated in multiple di f ferent directions simultaneously or at least without requiring the catheter 100 of FIG . 5 to be rotated or turned within the vessel during the treatment .

FIG . 6A shows a catheter, according to one or more embodiments shown and described herein, disposed in a venous system at a treatment site .

Firstly, the catheter 100 is introduced into a vessel V_1 through an access site (not shown) . The catheter 100 i s then advanced through the vessel V_1 to the treatment site where venous ablation is to be performed . The catheter 100 may comprise a rapid exchange tip 170 for following a guidewire 180 through the vessel V_1 to the treatment site . The catheter 100 may be advanced to the treatment side inside a cover, e . g . , in the form of a sheath .

As shown in FIG . 6A, the catheter 100 may have a long flexible section to more easily navigate tortuous vessel anatomy . Additionally or alternatively, the catheter 100 may comprise a plurality of sections as described in relation to FIG . 4 to more easily navigate tortuous vessel anatomy .

Once the catheter 100 is positioned at the treatment site as shown in FIG . 6A, the first electrode 130 may be transitioned from its radially contracted configuration to its radially expanded configuration . This may be achieved by a user pushing the proximal housing section 121 in a distal direction, i f the catheter 100 is configured as described in relation to FIG . s 2A and 2B . This can be done by the user through a handle which is connected at the proximal end of the catheter shaft 110 . Alternatively, i f the catheter comprises a cover configured to cover the first electrode 130 when the first electrode 130 is in the radially contracted configuration, this may be achieved by removal of a cover .

The increased height of the first electrode 130 in its radially expanded configuration allows the first electrode 130 to contact the wall W of the vessel VI . The first electrode 130 comprises at least one ablating structure 135 for ablating the venous endothelium provided on the intermediate portion of the respective electrode . The at least one ablating structure 135 i s in the form of a one or more wire hooks , speci fically five wire hooks as shown in the example of FIG . 6A.

The first electrode 130 may have a plurality of radially expanded configurations . The intermediate portion of the first electrode 130 may extend radially from the catheter body by a di f ferent respective amount in each radially expanded configuration so as to vary the height of the first electrode 130 . The catheter 100 may comprise a handle operable to control the extent of radial expansion of the first electrode 130 . Alternatively, this may be controlled by any other suitable means know to those skilled in the art . In this way, the catheter 100 may be adapted to the si ze ( e . g . , diameter ) of the vessel V_1 .

A current may then be supplied to the electrode 130 which causes the electrode 130 to heat up . In this way, energy, e . g . , RF energy, may be applied directly to the wall W of the vessel V_1 in order to ablate at least the endothelial layer E of the wall W of the ves sel V_1 . In addition, the wire hooks 135 function to mechanically ( i . e . , physically) damage , such as by scratching, scoring, abrading, denuding, etc . , at least the endothelial layer E of the wall W of the vessel V 1 . The combination of application of energy via the first electrode 130 and the scratching by the at least one ablating structure 135 may provoke an inflammatory response is the vessel V_1 .

In particular, as shown in FIG . 6B, as the catheter 100 is removed, the provoked inflammatory response results in the vessel shutting down . As such, after the catheter 100 is removed, the vessel 100 may heal shut , thereby closing of f the vessel and achieving venous ablation .

As a result of performing venous ablation in this way, blood flow may then be directed though other (preferably healthy) vessels V_2 and V_3 , as indicated by arrow A.

FIG . 7 is a schematic diagram il lustrating a process for performing venous ablation, according to one or more embodiments shown and described herein .

In process step S70 of FIG . 7 , a first electrode is positioned at a treatment site in a vessel while the first electrode is in a radially contracted configuration .

By way of example , the process of FIG . 7 may be performed using a catheter in accordance with one or more embodiments shown and described herein . For example , the catheter may be any of any the catheters described in relation to FIG . s 1 to 6 above .

Process step S70 may comprise any actions required to appropriately position the first electrode at the intended treatment site . For example , in the embodiments in which a catheter in accordance with one or more embodiments shown and described herein is used to perform the method, process step S70 may comprise a preceding step of inserting the catheter into a vessel through an access site .

By way of more detailed example , appropriately positioning of the first electrode may be achieved by using a rapid exchange tip and a guidewire as described in relation to FIG . 6A and/or by use of ultrasound imaging to determine the position of the first electrode . Additionally or alternatively, a catheter compri sing the first electrode may be advanced to the treatment s ite inside a cover, e . g . , in the form of a sheath . More generally, a catheter comprising the first electrode may be inserted into the vessel so as to appropriately position the first electrode at the treatment site by any suitable means know to those skilled in the art .

In process step S71 of FIG . 7 , a wall of the vessel is contacted with at least an intermediate portion of the first electrode by transitioning the first electrode from the radially contracted configuration to a radially expanded configuration .

Process step S71 may optionally comprise controlling an amount by which the intermediate portion extends radially in the radially expanded configuration in accordance with a si ze of the vessel . By way of example , the amount by which the intermediate portion extends radially may be measured with respect to a centre of the vessel , relative to the amount by which the intermediate portion extends radially in the radially contracted configuration or, in a case where the first electrode is comprised in a catheter, with respect to the body of the catheter . In embodiments in which a catheter in accordance with one or more embodiments shown and described herein is used to perform the method, process step S70 may comprise transitioning the first electrode of the catheter from a radially contracted configuration to a radially expanded configuration in which an intermediate portion of the first electrode is caused to extend radially from the catheter body for contacting a wall of the vessel .

By way of example , this may be implemented by removal of a cover and/or operation of a handle , or by any other suitable means known to those skilled in the art .

In process step S72 of FIG . 7 , at least an endothelial layer of the vessel is ablated by supplying RF energy to the electrode and applying the RF energy to the wall of the vessel via the intermediate portion .

In order to supply RF energy to the electrode , the electrode provided, e . g . , on a catheter in accordance with one or more embodiments herein, may be connected to an RF energy supply (not shown) , for example in the form of an electrosurgical (ESU) unit .

By way of example , suf ficient RF energy may be supplied to the electrode to provoke an inflammatory response . Such an inflammatory response may in turn prompt the vessel to shut down as the catheter is removed, thereby achieving venous ablation .

Process step S72 may optionally comprise controlling an amount of the RF energy applied to the wall of the vessel such that the first electrode does not ablate tissue outside the vessel .

Various modi fications will be apparent to those skilled in the art . The housing of the catheters of any of FIG.s 1 to 6A is not limited to a non-conductive ceramic material and may be made from any suitable material which can withstand the heat and current generated by the electrode 130. For example, the housing may be made from a polymer such as polyimide .

The catheters of any of FIG.s 1, 2, 4 and 5 may be adapted to include at least one ablating structure as described herein. Similarly, the catheters of either of FIG.s 3 and 6 may be adapted to not include at least one ablating structure .

The catheters of FIG.s 1 to 6A are not limited to the number of electrodes, number of radially expanded configurations and number of catheter body sections shown, but may be adapted to include any suitable number of sections, e.g. as described in relation to Figure 4, any suitable number of electrodes, and/or any suitable number or range of radial configurations.

The catheters of any of FIG.s 1 to 6A may be adapted to include any of the means to moving the first electrode between its radially contracted configuration and its radially expanded configuration, including but not limited to a pull wire, a cover, a first electrode in the form of a leaf spring, and/or the structure of the housing described in relation to FIG.s 2A and 2B.

The catheter of FIG. 1 may not comprise a catheter sleeve 150 or any of the catheters of FIG.s 2A to 6A may include such a catheter sleeve.

The shape of the electrode of the catheter or any of FIG.s 1 to 6A is not limited to a convex shape, but could be any other suitable shape, such as for example V-shaped, a trapezoidal shape, a triangular shape, or a rectangularshaped .

The electrode of the catheter or any of FIG.s 1 to 6A is not limited to a ribbon wire, but may be any other type of suitable wire, for example, a cylindrical wire or oval wire .

The catheter of any of FIG.s 1 to 5, as shown or modified as set out above, may be used as described in relation to FIG. 6 or in accordance with the process of FIG. 7.

All of the above are fully within the scope of the present disclosure and are considered to form the basis for alternative embodiments in which one or more combinations of the above described features are applied, without limitation to the specific combination disclosed above.

In light of this, there will be many alternatives which implement the teaching of the present disclosure. It is expected that one skilled in the art will be able to modify and adapt the above disclosure to suit its own circumstances and requirements within the scope of the present disclosure, while retaining some or all technical effects of the same, either disclosed or derivable from the above, in light of his common general knowledge in this art. All such equivalents, modifications or adaptations fall within the scope of the present disclosure.

Claims

1 . A catheter for venous ablation, comprising : a catheter body having a longitudinal axis ; and a first electrode disposed at least partially within the catheter body and having a distal portion, an intermediate portion and a proximal portion; wherein the first electrode is reversibly transitionable from a radially contracted configuration to a radially expanded configuration; and in the radially expanded configuration, the intermediate portion is configured to extend radially from the catheter body for contacting a wall of a vessel and to apply energy to the wall of the vessel for ablating at least an endothelial layer of the vessel .

2 . The catheter of claim 1 , wherein the first electrode comprises at least one ablating structure for ablating at least the endothelial layer of the vessel , the at least one ablating structure being provided on the intermediate portion .

3 . The catheter of claim 2 , wherein the at least one ablating structure comprises one or more wire hooks and/or teeth .

4 . The catheter of any preceding claim, wherein : the catheter further comprises a cover configured to cover the first electrode when the first electrode is in the radially contracted configuration; and the first electrode is transitionable from the radially contracted configuration to the radially expanded configuration by removal of the cover .

5 . The catheter of any of claims 1 to 3 , wherein : the catheter is part of an assembly comprising a handle ; and the first electrode is reversibly transitionable from the radially contracted configuration to the radially expanded configuration by operation of the handle

6 . The catheter of any preceding claim, wherein : the first electrode has a first radially expanded configuration and a second radially expanded configuration; the intermediate portion extends radially from the catheter body by a first amount in the first radially expanded configuration; and the intermediate portion extends radially from the catheter body by a second amount in the second radially expanded configuration, the second amount being di f ferent from the first amount .

7 . The catheter of any preceding claim, wherein the catheter further comprises a plurality of electrodes including the first electrode .

8 . The catheter of claim 7 , wherein the first electrode of the plurality of electrodes extends radially from the catheter body in a di f ferent direction to a second electrode of the plurality of electrodes .

9 . The catheter of claim 7 or claim 8 , wherein : the catheter body comprises a first section and a second section along the longitudinal axis ; and the first section comprises one or more electrodes o f the plurality of electrodes and the second section comprises a di f ferent one or more electrodes of the plurality of electrodes .

10 . The catheter of any of claim 7 to 9 , wherein each of the plurality of electrodes compri ses at least one ablating structure for ablating the venous endothelium, the at least one ablating structure being provided on the intermediate portion of the electrode .

11 . The catheter of any preceding claim, wherein the catheter body comprises a housing for housing the first electrode .

12 . The catheter of claim 11 , wherein the housing is a ceramic housing .

13 . The catheter of any preceding claim, wherein the first electrode is configured to not ablate tissue outside the vessel .

14 . The catheter of claim 13 , wherein : an amount by which the first electrode extends from the catheter body in the radially expanded configuration is configured such that the first electrode does not ablate tissue outside the vessel ; and/or an amount of the energy applied by the first electrode to the wall of the vessel is configured such that the first electrode does not ablate tissue outside the vessel .

15 . A venous ablation system comprising : a catheter in accordance with any preceding claim; and a radiofrequency generator for supplying radiofrequency energy to the first electrode .

16 . The venous ablation system of claim 15 , wherein : the radiofrequency generator is configured to supply radiofrequency energy at a low power such that plasma is not generated by the first electrode .

17 . A method of performing venous ablation, the method comprising : positioning a first electrode at a treatment site in a vessel while the first electrode is in a radially contracted configuration; contacting a wall of the vessel with at least an intermediate portion of the first electrode by transitioning the first electrode from the radially contracted configuration to a radially expanded configuration; and ablating at least an endothelial layer of the vessel by supplying RF energy to the electrode and applying the RF energy to the wall of the vessel via the intermediate portion .

18 . The method of claim 17 , wherein contacting the wall o f the vessel with at least the intermediate portion of the first electrode comprises : controlling an amount by which the intermediate portion extends radially in the radially expanded configuration in accordance with a si ze of the vessel .

19 . The method of claim 17 or 18 , wherein ablating at least the endothelial layer of the vessel further comprises : controlling an amount of the RF energy applied to the wall of the vessel such that the first electrode does not ablate tissue outside the vessel .

20 . The method of any of claims 17 to 19 , wherein positioning the first electrode at the treatment site comprises : inserting a catheter, comprising the first electrode , into the vessel through an access site .

21 . The method of any of claims 17 to 20 , wherein the method is performed using the catheter of any of claims 1