The invention is directed to an ablation catheter for treatment of a patient's tissue. In particular, the present invention relates to an ablation catheter that may be used for safely performing cardiac ablation procedures, such as, but not limited to, pulmonary vein isolation (PVI), persistent atrial fibrillation ablation, ventricular tachycardiac ablation. Further, the invention is directed to a method for operating such ablation catheter.

It is known to use ablation catheters in the therapy of atrial fibrillation (AF) patients. AF which may show as tachycardia or cardiac irregularity and may, especially if unnoticed, cause stroke, is often treated by electrically isolating the pulmonary vein (PV) from the left atrium by creating contiguous circumferential ablation lesions around the pulmonary vein ostium (PVO) or around their antrum. Thus, circular type ablation (also called circumferential type ablation) of the patient's tissue may be used to avoid irregular atrial contractions by hindering undesired perturbing electrical signals generated within the PV from propagating into the left atrium. Even though, ablation catheters may often be used to treat tissue of the left atrium or the PV, the ablation therapy is not limited to these regions and may also be provided to ventricles, right atrium, other organs such as lungs, liver, kidneys, etc.

To provide successful therapy, sometimes ablation of small local areas or points of tissue is necessary in addition to circular type ablation. For example, such type of ablation may be necessary if undesired perturbing electrical signals are generated in a small (focal) area, which spread out from this area in a circular pattern. For the ablation of such areas, separate ablation catheters providing focal ablation are used.

To perform ablation, several types of ablation catheters are available including single point tip electrode catheters, circular multi-electrode loop catheters, and balloon-based ablation catheters using different energy sources. However, to provide the two different types of ablation, i.e. focal and circular ablation, presently different ablation catheters must be used during the treatment of a patient. However, using two different ablation catheters to perform focal and circular ablation requires changing catheters during treatment, which is associated with a higher risk of complications for the patient and high costs. An exemplary ablation catheter known for circular ablation is disclosed in document US 10,172,673 B2 showing embodiments of ablation catheters comprising splines and respective electrodes configured to perform circular type ablation.

Consequently, it is desirable to further improve ablation treatment by providing an ablation catheter which allows both focal and circular ablation. Further, an objective is to indicate an easy, safe and cost-efficient operation method using such ablation catheter.

The above problem is solved by an ablation catheter with the features of claim 1 and a method for operating the ablation catheter with the features of claim 14.

In particular, an embodiment of an ablation catheter for treatment of a patient's tissue comprises:

• a guide tube having an inner lumen,

• a catheter shaft arranged within said inner lumen of said guide tube and moveable with respect to said guide tube,

• at least two splines fixed to the distal end of said catheter shaft, wherein each spline comprises a distally arranged first portion, a proximally arranged second portion, at least one first electrode fixed to or integrated within the first portion of the spline and at least one second electrode fixed to or integrated within the second portion of the spline,

• at least one steering wire, wherein one steering wire is connected to the first portion of at least one spline and moveable with respect to said guide tube and said catheter shaft, wherein the at least two splines are configured to take at least three configurations realized by a relative movement of said catheter shaft, said guide tube and said steering wire, wherein • in a first configuration said splines and said electrodes are fully arranged within said inner lumen of said guide tube,

• in a second configuration the first portion with the at least one first electrode of each of the at least two splines is fully arranged outside said guide tube and the second portion of the at least two splines is partly arranged outside said guide tube, wherein at least a part of the at least one second electrode is arranged within said inner lumen of said guide tube and

• in a third configuration the first portion with the at least one first electrode of each of the at least two splines is arranged fully outside said guide tube and the second portion with the at least one second electrode of each of the at least two splines is arranged outside said guide tube.

The ablation catheter is configured to deliver ablation treatment to the patient's tissue via the electrodes or a subset of the electrodes. In particular, the ablation catheter may be used to provide cardiac catheter ablation to treat a variety of cardiac arrhythmias including AF. The inventive catheter may also be used for different type of tissue, for example veins, lungs, liver, kidneys, and different therapy, for example to treat tumors. It may be used for pulmonary vein isolation (PVI), persistent atrial fibrillation ablation, ventricular tachycardiac ablation and other ablation procedures. In particular, the ablation catheter is suitable for isolating the ostium of vessels and thereby treating atrial fibrillation via the PVI approach. The guide tube and/or the catheter shaft may comprise a handle at its proximal end. Each electrode at the ablation portion is electrically connected via one electrode lead to a power supply and a pulse generator provided at the proximal end of the catheter.

In said first configuration of the splines, i.e. of the ablation catheter, the ablation catheter may be advanced to a target location, i.e. a location where an ablation may be performed, or retracted from said location in a minimally invasive fashion through the vasculature of the patient. In said first configuration the splines are arranged inside the inner lumen of the guide tube. Therefore, in the first configuration, the maximum outer diameter of the ablation catheter may be smaller than during any other configuration such as the second and the third configuration. The outer diameter may correspond to the outer diameter of the guide tube. The second and third configurations are described below in detail. In the second and third configurations are characterized by different forms of the splines projecting from the distal end of the guide tube and a different number of exposed electrodes. The second configuration and the third configuration are used to provide focal ablation and circular ablation, respectively.

Within said guide tube and, particularly, within the inner lumen of said guide tube, the catheter shaft is arranged. The catheter shaft has the shape of a cylinder or a hollow cylinder. The catheter shaft may be moveable, in particular slidably moveable, with respect to the guide tube. Stop means at the catheter shaft and/or the guide tube may be provided to prevent unintentional back and forth sliding of the catheter shaft with respect to the guide tube. The stop means may, for example, prevent or stop a transfer from the first to a second configuration or from a second to a third configuration and vice versa, so that for example an increased force must be applied at the beginning of the movement for the transfer from one configuration to another. The catheter shaft is moved by means of the handle provided at the proximal end of the guide tube or catheter shaft.

According to the invention, there are at least two splines fixed to a distal end of the catheter shaft. Each spline is a wire-like element which is connected with its first, proximal end to the catheter shaft and with its second, opposite end, e.g. the distal end, to the steering wire. In one embodiment in at least one configuration one section of the spline is located more distally than the second end. For example, at least six splines or eight to twelve splines may be fixed to said catheter shaft. The proximal end of each spline may be permanently fixed to the catheter shaft by any suitable means, in particular chemically (e.g. glued) or mechanically (e.g. arrested by a sleeve, welded at inner shaft braiding, welded or crimped at inner supporting tube, welded at catheter element such as x-Ray marker). In order to take the desired form in each configuration, the splines may be at least partly flexible, e.g. at least partly bendable. Further, each spline comprises at least two portions along its length, at least a distally arranged first portion and a proximally arranged second portion.

'Distal' is used herein to specify a direction along the longitudinal extension of the catheter, end or surfaces which are arranged or are to be arranged to face or point towards an end of the ablation catheter used for ablation. In contrast, 'proximal' is used to indicate a direction along the longitudinal extension of the catheter, end or surfaces which are arranged or are to be arranged away from or point away from the end of the ablation catheter used for ablation, i.e. the direction opposite the distal direction. Thus, during ablation, the ablation location may be in contact with a more distal end of the ablation catheter, wherein a more proximal end may be closer to an operating health care practitioner (HCP).

The ablation catheter additionally comprises at least one steering wire, wherein one steering wire is connected to the first portion of at least one spline and moveable with respect to said guide tube and said catheter shaft. The steering wire extends along the longitudinal direction of the catheter (i.e. extension of guide tube, catheter shaft). There may be only one single steering wire connected to the first portions of all splines or multiple steering wires, wherein, for example, the first portion of each spline is connected to a separate steering wire. In one embodiment, the steering wire is fixed to the distal end of the respective spline and, i.e. to the distal end of the first portion of the respective spline. Once the at least one steering wire is pulled into the proximal direction, it may apply a tensile force to the first portion of the spline to which the steering wire is connected. Alternatively, if the steering wire is pushed in the distal direction, a pushing force may be applied to said first portion of the splines. In one embodiment, at least one steering wire may be connected to a distal tip of a respective spline. In order for the at least one steering wire to be operated individually or together and thereby moved independent with respect to the guide tube and the catheter shaft, for example by an HCP, the at least one steering wire may be guided through passage opening(s) of the catheter shaft individually or together.

Each spline of the at least two splines comprises at least one first electrode fixed to or integrated within the first portion of the spline and at least one second electrode fixed to or integrated within the second portion of the spline. If all splines are connected to a single steering wire, a single first electrode per spline may be provided near this connection point. The first portion may comprise, for example, two or three first electrodes, wherein the second portion may comprise, for example, two to five second electrodes. Each of the first and second electrodes is connected via an electric lead to a power source, e.g. a RF or PFA generator, connected to the proximal end of the catheter. The electric lead may be located within the spline and the catheter shaft. Each first and second electrode comprises an electrically conducting face which is configured to contact the patient's tissue at the target area for ablation.

By a respective relative movement of the catheter shaft, the guide tube and the at least one steering wire, the at least two splines are configured to realize at least three configurations. More than three configurations are possible, as well. One of said three configurations is the aforementioned first configuration, wherein the splines and the electrodes are fully arranged within the inner lumen of the guide tube. The first configuration is used, for example, to advance the ablation catheter to the ablation location or to retract the ablation catheter when the ablation catheter is removed from the patient's body. In one embodiment, the ablation catheter may also take on a first configuration during repositioning after an ablation was provided in a second configuration and/or a third configuration.

In the second configuration, in which the first portion of the respective splines with the at least one first electrode of each of the at least two splines are fully arranged outside said guide tube, at least a part of the at least one second electrode and a part of the second portion are still be arranged inside the guide tube. If the second portion comprises more than one electrode and the ablation catheter is in the second configuration, it is equally possible for only the foremost, i.e. the most distal, electrode to be located fully outside the guide tube, wherein more proximal second electrode(s), if present, is/are located within the guide tube. In one embodiment, all second electrodes of each spline are located within the guide tube in the second configuration. The partial arrangement of an electrode outside the guide tube according to the above definition of the second configuration describes a condition in which one single electrode is arranged either within or without said guide tube but part of a number of electrodes is arranged inside said guide tube and the rest of the number of guide tubes is arranged outside said guide tube, i.e. outside the inner lumen of the guide tube.

In a similar way, this applies to the ablation catheter in a third configuration, in which the first portion with the at least one first electrode of each of the at least two splines are arranged fully outside said guide tube and the second portion with the at least one second electrode of each of the at least two splines are arranged outside said guide tube, wherein a part of the second portion may still be arranged within the guide tube. This means that in the third configuration a greater part of the second electrodes are arranged outside said guide tube than in the second configuration. For example, in the second configuration all first electrodes of the first portion are arrange outside the guide tube whereas all second electrodes of the second portion are arranged within the inner lumen of the guide tube. In this example, in the third configuration all second electrodes are arranged outside the guide tube, too.

As explained below, transferring the ablation catheter and therefore the splines between the at least three configurations, does not only determine the different position of the splines and the corresponding electrodes with respect to the guide tube, but also determines the shape of the splines projecting from the distal end of the guide tube, which changes in one configuration compared to the other. It is noted that the cross section of the individual spline is not changed when the catheter transfers from one configuration to another configuration. For example, when the splines are moved out of the guide tube or the guide tube is retracted while the delivery catheter is transferred from the first configuration into the second or third configuration, the first and/or the second portion of the spline may bend and/or rotated.

Additionally, the steering wire may be pulled leading to further form change of the respective spline. Thus, even though the ablation catheter or the splines may have an essentially rectilinear shape or a shape corresponding to that of the guide tube in the first configuration, the splines may take on a different shape in a second configuration and/or a third configuration. For example, the enclosed shape of all splines may be a basket-like form, a mushroom form or bulbous/bellied form in the second or third configuration whereas the spline shape in the first configuration is similar to the inner lumen of the guide tube. Additionally, in the second and third configuration the first portion may extend generally straight and radially from the joint steering wire with regard to the longitudinal extension of the catheter (e.g. the steering wire or the catheter shaft) wherein the second portion has a generally bulbous/bellied form. The form may be chosen such that in the second configuration at least the first electrodes of the splines get in contact with the focal ablation target area of the patient's tissue for focal ablation, wherein in the third configuration at least the second electrodes of the splines get in contact with the circular ablation target area of the patient's tissue for circular ablation. In one embodiment, the ablation catheter is configured to perform focal ablation in the second configuration and configured to perform circular ablation in the third configuration. Accordingly, the form of the splines may be chosen as indicated above. 'Focal ablation' thereby describes the ablation of a coherent (focal) area or point of a pre-defined two-dimensional extension, wherein within this area/point all tissue or at least the predominant part of the tissue is ablated. In contrast, 'circular ablation' isolates an inside area of tissue from an outside area of tissue by an ablated circular or similar area, wherein the ablated circular area encircles the inside area. The circular ablation may be applied, for example, by circular ablation around a vein or its ostium such as PVI. The form of the ablation line of the circular ablation may be circular, elliptical, triangular, quadrangular, pentagonal etc. The ablation line may encircle the inside area fully or at least for the most part. Accordingly, the different ablation types (i.e. focal vs. circular ablation) may be realized using the same catheter only by moving the guide tube relative to the catheter shaft and, if applicable, additionally the at least one steering wire along the longitudinal extension of the catheter.

The size, i.e. the length, of the first portion of the splines, the location of the first (ablation) electrodes may define the size of the focal ablation area. Similarly, an outer radius of a circular ablation line produced in the third configuration depends on the length of the second portion of the splines, the location of the second (ablation) electrodes and the part which is arranged at least partially outside the guide tube in the third configuration. The splines may further be configured to realize more than three configurations, wherein for example for repositioning and/or configurations to perform focal ablation in areas of different size and/or to perform circular ablation with different outer radius of the ablation line. Thereby the ablation line could be adapted to different anatomies, e.g. different PV diameters.

In one embodiment, the first portion of each spline comprises an outer diameter and/or a material different from the outer diameter and/or the material of the second portion. The splines may be formed - regarding their cross section - as a solid circle or a hollow circle cross-section or any other round or angular cross section. By using different outer diameters, the stiffness of the first portion and stiffness of the second portion of each spline may differ from one another. Providing different stiffnesses for the first portion and for the second portion may also be achieved alternatively or additionally by using different materials for the first portion and the second portion of each spline, wherein, in one embodiment, the different materials have different elastic modulus. In general, all materials used, especially those which may contact the tissue may be biocompatible materials. For example, the first portion and the second portion may comprise at least one material of the group comprising shape memory alloys as Nitinol, spring steel like X10CrNil8-8; 38Si7 and C67E / C67S. Hence, comprising 'a different material' may be understood as comprising a different average material composition throughout the portion, wherein 'a different outer diameter' may be understood as comprising a different maximum outer diameter or average outer diameter throughout the portion. The outer diameter of the first portion is, for example, 0.81mm and the outer diameter of the second portion is, for example, 0.61 mm.

In one embodiment the material of each spline comprises a shape memory alloy. The shape memory material may be a super-elastic material (such as a super-elastic alloy), for example, Nitinol. In one embodiment, the at least two splines may comprise an inner support wire, having a shape memory or super-elastic property, e.g. Nitinol. The support wire may have various stiffness and cross-sectional shapes in different sections. The inner support wire maintains the form integrity of the splines and extends along at least one section of the first portion and/or the second portion of the splines. The inner support structure may be realized, for example, with a round, rectangular, square cross section, for example with variable cross section or tapered). In addition, the at least one spline may comprise insulating material, for example Parylene, Polyimide, Teflon at its outer surface.

In one embodiment of the present disclosure, the outer diameter of the first portion is greater than the outer diameter of the second portion. As a result, the portion with a greater outer diameter, in this case the first portion, has a higher stiffness than the second portion. The procedure of a respective movement of the guide tube, the catheter shaft and the at least one steering wire, wherein the ablation catheter takes on different configurations, as described before, may be supported by a second portion being less stiff compared to the first portion. By providing portions with different stiffness, the above described forms of the respective spline in the different configuration may be realized in an easy and cost-effective way. In one embodiment, each spline comprises a third portion arranged in between the first portion and the second portion, wherein the third portion forms a transition portion with regard to the directly adjacent first portion and the directly adjacent second portion. The transition portion may comprise a different material and/or outer diameter compared to the first portion and/or the second portion. In one embodiment the third portion may further comprise electrodes as described before with respect to the first portion and the second portion of a spline. The transition portion may represent a gradual transition between adjacent portions in terms of diameter and/or material composition. For this purpose, the third transition portion may, for example, have a conical shape.

In one embodiment, the second configuration and/or the third configuration is pre-formed during manufacturing of the catheter so that once the splines are transferred into said second configuration and/or said third configuration each spline returns to said pre-formed state. Pre-forming of said splines may be realized by kinking said splines in a predetermined manner, for example by biasing said splines in the first configuration, or by using a shape memory alloy. The first and second portions of the at least two splines take their pre-formed state in the second and/or third configuration. For example, the first portion and the second portion of one spline may form a pre-defined angle as a result of the pre-forming process, for example, an angle between 60 degrees and 120 degrees.

In one embodiment, each spline has a maximum outer diameter between 0.3 mm and 1 mm, for example between 0.3 mm and 0.7 mm, and/or the guide tube has a maximum outer diameter of 3.5 mm, for example the maximum outer diameter of the guide tube is 3 mm. The outer diameter of each spline may depend on the number of electrodes being arranged on this spline and/or on the way this electrode are electrically connected by electrode leads.

In one embodiment, at least one spline comprises at least one additional electrode configured to detect electromagnetic signals from the tissue prior and/or during ablation. In one embodiment, each of the at least two splines may comprise such additional electrode. The additional electrode which is solely used for detecting electromagnetic signals may be a so-called sensing electrode. The signals received from the at least one additional electrode may be used for electro-anatomical mapping of the respective electromagnetic signal. The at least one sensing electrode of a spline, i.e. the additional electrode, is configured for receiving electromagnetic signals, e.g. electrical potentials and/or electrical currents, from (surrounding) vascular or atrial tissue. Additional electrodes may have a similar structure compared with the ablation electrodes but the exposed face may have a dimension slightly smaller than the ablation electrodes in order to provide a higher electrical signal resolution. In one embodiment, additional electrodes (for example having a length of 1 mm) may be positioned between two ablation electrodes. The detected electromagnetic signals may be transmitted from the additional electrode via a respective electrode lead to the electronic control unit. Using the at least one additional electrode, it is possible to observe the ablation result and its progress during ablation. At least a part or each of the first, second and/or additional electrodes may comprise, as a suitable material, for example, at least one of gold and a plati- num/iridium alloy, at least at its exposed surface.

In a further embodiment, the at least one first electrode and the at least one second electrode are configured to provide monopolar ablation. In another embodiment, the first portion comprises at least two first electrodes configured to provide bipolar ablation and/or the second portion of the at least two splines comprises at least two second electrodes configured to provide bipolar ablation. During monopolar ablation the energy is always delivered from an active electrode placed inside the patient's body to a reference electrode, which may be outside the patient's body. For bipolar ablation, the ablation energy is delivered locally between two adjacent electrodes.

In one embodiment, the at least one first electrode and/or the at least one second electrode and/or the at least one additional electrode is formed by an electrically conducting surface section of the spline accommodated along its respective first portion and/or its respective second portion, wherein electrodes located adjacently along one spline are electrically insulated from each other, the connected steering wire and the catheter shaft. By forming electrodes as electrically conducting surface sections of the spline, the spline has a smaller outer diameter which may help to provide more splines within a limited maximum outer diameter of a guide tube. When electrodes are formed by electrically conducting surface sections, the electrode leads run typically inside the spline. In one aspect of the present disclosure, the ablation catheter is configured to provide radio frequency ablation (RFA) and/or pulsed field ablation (PF A). The RFA energy as well as the PFA energy may be delivered in a monopolar arrangement or in a bipolar arrangement or in a combination of a monopolar arrangement and a bipolar arrangement. In order to provide PFA, the ablation catheter is configured for delivering PFA energy to atrial or ventricular tissue via the ablation electrodes. In PFA, for example for the treatment of AF, a sequence of high-amplitude electrical pulses with a duration of microseconds are emitted, wherein myocardium is ablated by electroporation without significant tissue heating. In RFA, heat is generated by a medium frequency alternating current, wherein said heat is used to ablate respective tissue.

In one embodiment, the connection of the first portion of each spline to the respective steering wire is flexible. When the ablation catheter is transferred from its first configuration into a subsequent second or third configuration, the longitudinal axis of the first portion of each spline and the longitudinal axis of the steering wire may form an angle of about 60 degrees to 120 degrees. However, during the first configuration, i.e. when the spline is arranged inside the inner lumen of the guide tube, the first portion is parallel or generally parallel to the steering wire. Thus, when the ablation catheter is in the second configuration or the third configuration, the flexible connection of the first portion to the steering wire may cause the formation of the above mentioned angle between the first portion and the steering wire.

In one embodiment, the ablation catheter comprises an electronic control unit (ECU) configured to control operation of each of the at least one first electrode, each of the at least one second electrode and, if applicable, each of the at least one additional electrode, wherein the ECU uses a computing processor. The ECU controls the electrodes such that monopolar and/or bipolar ablation as well as PFA or RFA may be provided. A switch unit, which may be separate or an integral part of the ECU and controlled by the ECU, may be used to switch the electrodes so that desired monopolar and/or bipolar ablation as well as PFA or RFA is realized. The switch unit may comprise a respective switch matrix.

In one embodiment, the operation control of the ECU comprises and/or realizes an ablation mode and a sensing mode with regard to the at least one first electrode and/or the at least one second electrode. This means that this at least one electrode may be switched between the sensing mode and/or the ablation mode, wherein in the sensing mode the respective electrode senses the surrounding electromagnetic signals of the tissue and in the ablation mode the respective electrode provides a pre-defined ablation signal. The ECU may be configured to only switch the mode of all electrodes, a single electrode or of a subgroup of all electrodes at a pre-defined, specific time. In order to ease and improve assessment the received electromagnetic signals of the sensing electrodes the ECU may be configured to visualize the signals with regard to their local distribution using standard imaging technology (so-called electro-anatomical mapping).

In a further embodiment, the impedance may be measured using the first, second and, if applicable, the additional electrodes in order to determine the relative distance between predefined spline portions of different splines when they contact patient's tissue. If the measured impedance is lower than a predefined impedance threshold, the respective electrodes may be characterized to be too close to each other which should be avoided in order to prevent, for example, spark and/or incineration. Further, monopolar impedance may be determined in order to prove uniform distribution of the electrodes and to thereby ascertain that a predefined set of electrodes is in contact with the patient's tissue along its entire outer surface in order to provide the desired ablation.

In one embodiment, in the first configuration the first portion of each spline is located distally from the distal end of the connected steering wire. Consequently, the section of the first portion which is connected to the steering wire is arranged more proximal than a further part of the first portion. As the first portion is located more distal than the distal end of the steering wire, the first portion as well as the second portion run at least partially along same portions of the inner lumen of the guide tube, while being in the first configuration. This arrangement of the first portion and the second portion facilitate advantageous forms of the at least two splines in the second and the third configuration well suitable for focal and/or circular ablation, e.g. the "mushroom" form.

Analogously, the invention refers to a method for operating the ablation catheter according to the above specification, wherein said method comprises the following steps: • inserting the ablation catheter into a patient's body and moving the ablation catheter along the patient's vasculature until a pre-defined first ablation location/tar- get is reached while the at least two splines take their first configuration,

• transferring the at least two splines of said ablation catheter from the first configuration into the second configuration or into the third configuration by a respective relative movement of the catheter shaft, the guide tube, and/or the steering wire such that the at least one first electrode or the at least one first electrode and the at least one second electrode contact(s) the tissue at the pre-defined first ablation location/target and provide an ablation treatment using the electrodes in contact with the tissue at the pre-defined first ablation location,

• transferring the at least two splines of said ablation catheter to the other one of the second configuration and the third configuration by a respective relative movement of the catheter shaft, the guide tube, and/or the steering wire such that the at least one first electrode or the at least one first electrode and the at least one second electrode contact(s) the tissue at a pre-defined second ablation location/target and provide an ablation treatment using the electrodes in contact with the tissue at the pre-defined second ablation location/target.

Standard cardiac treatment and ablation involves inserting the catheter into a vein in the groin and advancing it to a first ablation location within, for example, the heart of the patient. However, depending on the ablation location, i.e. depending on whether a cardiac treatment or a treatment of a different organ will be performed, other inserting location may be used. During advancement of the ablation catheter towards the first ablation location (target), the ablation catheter is in its first configuration, which is essentially characterized by the fact that in this configuration the outer diameter of the ablation catheter is the smallest.

Once the ablation catheter reaches the first ablation location, the ablation catheter is transferred from the first configuration in any subsequent configuration, e.g. the second configuration or the third configuration, by a respective relative movement of the catheter shaft, the guide tube, and/or the steering wire. The ablation catheter in the second configuration or the third configuration comprises in general a greater outer diameter in any of these configurations than in the first configuration. By increasing the outer diameter and/or simply by moving the splines with the respective electrodes at least partially out of the inner lumen of the guide tube and thereby by transferring the ablation catheter from the first configuration in the second configuration or in the third configuration the at least one first electrode or the at least one first electrode and the at least one second electrode contact(s) the tissue at the pre-defined first ablation location. Next, an ablation treatment using the electrodes in contact with the tissue at the pre-defined first ablation location is provided. Usually, the first ablation location is determined by the HCP prior ablation and prior inserting the ablation catheter into the patient's body. If applicable, based on measured electromagnetic signals by electrodes of the catheter as indicated above, the first ablation location may (slightly) be changed by respective movement of the splines with the catheter.

After ablation was performed at a first ablation location, the ablation catheter and the respective at least two splines are transferred to the other one of the second configuration and the third configuration by a respective relative movement of the catheter shaft, the guide tube, and/or the steering wire. This causes the at least one first electrode or the at least one first electrode and the at least one second electrode to contact the tissue at a pre-defined second ablation location. Additionally, the ablation catheter and thereby the splines at its distal end may be moved with regard to the tissue to be treated. At the second pre-defined ablation location to the ablation catheter provides an ablation treatment at the second ablation location, the electrodes provide a respective ablation treatment at the pre-defined second ablation location.

In one embodiment, the method further comprises at least one of the following steps:

• detecting electromagnetic signals from the tissue at and/or around the pre-de- fined first ablation location and/or at and/or around the pre-defined second ablation location,

• repositioning of said ablation catheter at the tissue after one ablation treatment is provided with or without changing the configuration of the at least two splines and providing a second ablation treatment at a slightly changed position,

• transferring said splines of said ablation catheter into the first configuration after the ablation treatment is finished, • controlling said electrodes of said splines by the ECU to provide radio frequency ablation and/or pulsed field ablation

• controlling said electrodes of said splines by the electronic control unit to provide unipolar ablation and/or bipolar ablation.

Detecting electromagnetic signals may be used to identify a pre-defined ablation location such as the first ablation location and the second ablation location, whether the electrodes and the splines respectively are in a correct position in order to perform successful ablation or the progress of the ablation and thereby identify, for example, an appropriate time to terminate the ablation. Further, detected electromagnetic signals may be used for mapping etc.

As aforementioned, a repositioning of the ablation catheter may be used for ablating at a different location from a previously performed ablation location. For example, in the third configuration the catheter is slightly rotated in order to ablate a full circular line while circular ablation. During repositioning, a change of configuration of the splines and/or a change of ablation type (monopolar, bipolar, PF A, RFA, etc.) may be conducted, if necessary or desired.

After the ablation treatment is finished, the ablation catheter may be transferred into the first configuration in order to retract the ablation catheter and to remove the ablation catheter from the patient's body.

Further, the electrodes may be controlled by the ECU to provide RFA or PF A. In addition, or as an alternative, the ECU may be used to control the electrodes of the splines to provide monopolar ablation and/or bipolar ablation as described above.

The various features and advantages of the present invention may be more readily understood with reference to the following detailed description and the embodiments shown in the drawings. Herein schematically and exemplarily,

Fig. 1A to ID depict four different embodiments of a spline in a cross sectional view; Fig. 2A to 2D illustrate different configurations of a first embodiment of an ablation catheter comprising splines according to Fig. 1C in a side view and partly cross-sectional view;

Fig. 3 shows a second embodiment of an ablation catheter in a side view and partly cross-sectional view;

Fig. 4A to 4B show a third and a fourth embodiment of an ablation catheter in a third configuration in a side view and partly cross-sectional view;

Fig. 5 and 6 depict a fifth embodiment of an ablation catheter in a third configuration in a side view and partly cross-sectional view and in a top view;

Fig. 7 and 8 depict a sixth embodiment of an ablation catheter in a second and third configuration, each in a side view and partly cross-sectional view; and

Fig. 9 shows an embodiment of an ECU with its connection to the electrodes of an ablation catheter.

Each of a first to a sixth embodiment of an ablation catheter 1, 2, 3, 4, 5, 6 according to the invention is configured to realize at least three configurations, wherein in particular the design of at least two splines 20, 21, 22, 23 of said ablation catheter 1, 2, 3, 4, 5, 6 is decisive for the ablation properties of this catheter as indicated below.

Exemplary embodiments of splines 20, 21, 22, 23 usable for the ablation catheters 1, 2, 3, 4, 5, 6 are depicted in Fig. 1 A to ID, wherein different configurations of five different embodiments of ablation catheters 1, 2, 3, 4, 5, 6 are depicted in Figs. 2A to 8.

During the insertion of an ablation catheter 1, 2, 3, 4, 5, 6 into a patient's body and while moving said ablation catheter 1, 2, 3, 4, 5, 6 along the patient's vasculature until a pre-defined first ablation location is reached the ablation catheter is in a first configuration shown in Fig. 2A and 3. However, once the ablation catheter 1, 2, 3, 4, 5, 6 reaches a pre-defined ablation location it may be transferred from the first configuration into a second configuration depicted in Fig. 2B and 7 or a third configuration depicted in Fig. 2C, 2D, 4A, 4B, 5, 6 and 8.

The first embodiment of an ablation catheter 1 shown in Fig. 2A to 2D comprises a guide tube 10 with an inner lumen 11, a cylindrical catheter shaft 12 arranged inside said inner lumen 11 of the guide tube 10 and moveable with respect to said guide tube 10. Further, the ablation catheter 1 comprises one steering wire 13 which is also moveable relative to said guide tube 10 and said catheter shaft 12 and connected with its distal end to a distal end of a first portion 32 of four splines 22. The guide tube 10, the catheter shaft 12 and the steering wire extend along the longitudinal direction of the catheter. The steering wire 13 is configured to apply a force onto the first portion 32 of each spline 22 once pulled and/or pushed, for example by a HCP. Therefore, the steering wire 13 may run through a passage opening of the catheter shaft 12. At the proximal end of the ablation catheter 1 (arrow P denotes the proximal direction) a handle (not shown) is provided for mechanical manipulation of the catheter, for example, the guide tube 10, the catheter shaft 12 and/or the steering wire 13 to which the handle is connected.

Each of the splines 22 of the ablation catheter 1 further comprise a second portion 42 located proximally from the first portion 32. Each first portion 32 comprises a first electrode 50 and each second portion 42 comprises a second electrode 51.

In order to transfer the ablation catheter 1 from the first configuration into second or third configuration or from the second or third configuration into the first configuration a relative movement of the guide tube 10, the catheter shaft 12 and/or the steering wire 13 is facilitated. To transfer the ablation catheter 1 from its first configuration shown in Fig. 2A into the second configuration shown in Fig. 2B, the catheter shaft 12 may be pushed in a distal direction (see arrow D) or by retracting the guide tube 10 in proximal direction (arrow P). By pushing said catheter shaft 12 into the distal direction D or retracting the guide tube 10 into the proximal direction P, splines 22 are partially moved out of the inner lumen 11 of the guide tube 10, the first portion 32 with the first electrode 50 of each of the splines is moved outside the guide tube 22. Further, a distal end of the second portion 42 is also moved out of the inner lumen 11 of the guide tube 10 but the electrodes 51 still remain within the inner lumen 11. In order to realize the "mushroom" form of the wires forming the second configuration of the ablation catheter 1 depicted in Fig. 2A, the steering wire 13 is pulled in the proximal direction P so that the distance between the distal end 14 of the catheter shaft 12 and the distal end of the steering wire 13 is shortened.

As shown in Fig. 1C in more detail the first portion 32 of each spline 22 has a greater outer diameter DI compared with an outer diameter D2 of the second portion 42. Both portions 32, 42 are made of the same material, for example Nitinol. The greater diameter DI of the first portion 32 causes a higher stiffness of the first portion 32 compared with the second portion 42. Due to the higher stiffness, in the second configuration shown in Fig. 2B the first portions 32 of each spline 22 form straight sections projecting radially outside from the distal end of the steering wire 13 with regard to the longitudinal axis of the guide tube 10 or the catheter 1. Thereby, the first electrodes 50 are star-shaped accommodated forming a small ablation area with a diameter of 10 mm to 15 mm for focal ablation.

Fig. 1 A, IB and ID show different embodiments of a spline. In the embodiments of Fig. 1 A and IB a first material of a first portion 30, 31 of the spline 20, 21 has a greater stiffness than a second material of a second portion 40, 41.

In the embodiment of Fig. IB of a spline 21 there is a third portion 61 in which the material forms a gradual transition from the first material of the first portion 31 to the second material of the second portion 41.

The embodiment of a spline 23 depicted in Fig. ID is similar to the embodiment shown in Fig. 1C, in particular a first portion 33 is similar to the first portion 32 of the embodiment of Fig. 1C and a second portion 43 is similar to the second portion 42 of the embodiment of Fig. 1C, but has additionally a transition portion 63, which has a conical shape and thereby forms a transition from the first diameter DI of the first portion 33 to the second diameter D2 of the second portion 43. The first material of the first, second and third portions 33, 43, 63 of the spline 23 is identical, for example Nitinol.

Further, the ablation catheter 1 may be transferred to a third configuration. Exemplary third configurations of this catheter embodiment are shown in Fig. 2C and 2D. To realize the third configuration, the catheter shaft 12 is moved further distally with respect to the guide tube 10. As shown, the catheter shaft 12 may be still be covered by the guide tube 10 in the third configuration but the splines 22 are fully located outside the guide tube 10. For example, the catheter shaft 12 may be prevented from being pushed out from the guide tube 10 by mechanical means provided within the guide tube 10 and/or at the catheter shaft 12. Simultaneously with the distal movement of the catheter shaft 12 into the distal direction D or the proximal movement of the guide tube 10, the steering wire 13 is moved in the proximal direction P and the distance between the distal end 14 of the catheter shaft 12 and the distal end of the steering wire 13 and analogously the distance between the distal end 14 of the catheter shaft 12 and the first portions 32 of the splines 22 is shortened. Accordingly, the second portions 42 of the splines 22, move further outwards, i.e. further outwards in the radial direction of the ablation catheter 1, increasing the outer diameter formed by the respective configuration of the splines. In addition, the second electrodes 51 located at the second portions 42 are moved out of the guide tube 10. The basket-like shape formed by the ablation catheter 1 and the splines 22 in the third configuration is used for circular ablation provided by the second electrodes 51, wherein the diameter of the circular ablation provided by the configuration of the catheter 1 shown in Fig. 2D is greater than the diameter of the circular ablation provided by the configuration of the catheter 1 shown in Fig. 2C.

The embodiments of the splines shown in Fig. 1A, IB and ID may also be used with the catheter 1 depicted in Fig. 2A to 2D. Each first, second and third portion may comprise a suitable number of first electrodes 50, second electrodes 51 and additional electrodes 52 (see below).

The following explanation of further embodiments of ablation catheters 2, 3, 4, 5, 6 refers to Fig. 3, 4A, 4B, 5, 7, 8 in which only one single spline is depicted and to Fig. 6. However, the ablation catheters have, for example, 6 or 8 splines.

First and second electrodes 50, 51 of the respective first portion 32, 33 and second portion 40, 41, 42, 43, respectively, may be used for ablation and/or sensing electromagnetic signals. The splines may further comprise additional electrodes 52 for sensing only. These additional electrodes 52 may be located at a third (transition) portion 61 as shown, for example, for spline 21 in Fig. IB. Additionally or alternatively the additional electrodes 52 may be located at the first portion 30 (Fig. ID), at the second portion 50 (Fig. 1 A) or at the first portion 33 and the second portion 43 (see Fig. ID, 4B). The arrangement of the electrodes along the splines depends on whether monopolar, bipolar, PF or RF ablation is to be performed for focal ablation or circular ablation.

Fig. 4a shows an embodiment of a catheter 3 which is similar to the embodiment shown in Fig. 2A to 2D but the first portion 32 of each spline 22 is so stiff due to its greater outer diameter compared to the second portion 42 that the first portion 32 stays straight in the second and third configuration, wherein the third configuration is shown in Fig. 4A.

The embodiment of a catheter 2 shown in Fig. 3 has a greater stiffness of the first portion 30 of the spline 20 compared with the stiffness of the second portion 40. A detailed view of the spline 20 is depicted in Fig. 1A and is described above. Fig. 3 shows the catheter 2 in the first configuration, wherein the first portion 30 is located distally from the distal end of the steering wire 13. Accordingly, the first portion 30 of the splines 20 of catheter 2 is "flipped over" compared with the first configuration of the splines 22 of catheter 1 shown in Fig. 2A. Depending on the specific construction of the splines and the steering wire(s) 13 this first configuration may be more space-saving than the first configuration shown in Fig. 2A.

Fig. 4B shows an embodiment of a catheter 4 comprising splines 23 which are depicted in Fig. ID. Each spline 23 has a first portion 33 with a greater outer diameter DI compared with the outer diameter of a second portion 43. Further, a third portion 63 as a transition portion is located between the first portion 33 and the second portion 43. The third portion 63 has a conical shape. Further, each of the first portion 33 and the second portion 43 comprises two ablation electrodes 50, 51 and two sensing electrodes 52.

The ablation and/or sensing electrodes 50, 51, 52 may also be formed by an electrically conducting surface section of a spline of 22 of a catheter 5 as shown in Fig. 5 and 6. Fig. 5 depicts only one spline 22 in the third configuration, wherein the spline 22 is basically similar to the detailed view shown in Fig. 1 C - the first section 32 has a greater diameter DI compared with the diameter D2 of the second section 42. Fig. 6 shows all eight splines 22 in the third configuration in a top view. Further, each spline 22 has a separate steering wire 13 which means there are eight steering wires 13 which may be jointly operated from the proximal end of the catheter 5. The respective electrically conducting surfaces forming said electrodes 50, 51, 52 may be accommodated along the portions of a spline. However, neighboring electrodes are electrically insulated from one another by an electrical insulating surface section 70 located between the adjacent electrically conducting surfaces 50, 51, 52. In addition, the electrodes are electrically insulated from the catheter shaft 12 and the steering wire 13 by electrical insulating surface section 70. By using electrically conductive sections as electrodes, the overall outer diameter of the splines is reduced.

The sixth embodiment of a catheter 6 is shown in Fig. 7 and 8 which is basically similar to the first embodiment shown in Fig. 2A to 2D. However, the first portion 32 of spline 22 comprises three first electrodes 50 and the second portion 42 comprises two second electrodes 51. Using two electrodes for each portion 32, 42, a bipolar ablation may be provided as focal ablation using the first electrodes 50 in the second configuration depicted in Fig. 7 and a bipolar ablation may be provided as circular ablation using the second electrodes 51 in the third configuration shown in Fig. 8. One of the first electrodes 50 may be used in the sensing mode detecting the electric potential close to the ablation target, whereas the two other first electrodes 50 are operated in the ablation mode as described above.

In order to provide ablation to a tissue at an ablation location, the ablation electrodes 50, 51 are electrically connected to a power source (not shown) located at the proximal end of the catheter 1, 2, 3, 4, 5 via conducting leads which run along (e.g. within) the splines 20, 21, 22, 23, 24 and the catheter shaft 12. The operation of the electrodes 50, 51, 52 is controlled using an electronic control unit (ECU) 100 (see Fig. 9). The ECU 100 provides a switching between the different operation modes, namely the sensing mode and the ablation mode as described above using a switch unit 101. Additional, a signal generator 102 is provided producing and transmitting the electrical pulses required for ablation, to the electrodes 50, 51. The ECU 100 further analyses the electromagnetic signals (e.g. electrical potential, impedance) received from the electrodes 52 and/or the electrodes 50, 51 in the sensing mode. When the ablation is terminated and the result of the ablation, i.e. its success, was controlled by sensing electromagnetic signals, the ablation catheter takes on its first configuration again. Once the ablation catheter is fully retracted, it will be removed from the patient's body.

List of reference numerals

1, 2, 3, 4, 5, 6 Ablation catheter

10 Guide tube

11 Inner lumen

12 Catheter Shaft

13 Steering wire

14 Distal end

20, 21, 22, 23 Spline

30, 31, 32, 33 First portion

40, 41, 42, 43 Second portion

50 First electrode

51 Second Electrode

52 Additional electrode

61, 63 Third portion (transition portion)

70 Electrical insulation

100 Electronic control unit (ECU)

101 Switch unit

102 Signal generator

D Distal direction

DI Outer diameter (first portion)

D2 Outer diameter (second portion)

P Proximal direction