Patent Description:
Catheters are flexible, tubular devices that are widely used by physicians performing medical procedures to gain access into interior regions of the body. Certain types of catheters are commonly referred to as irrigated catheters that deliver fluid to a target site in an interior region of the body. Such irrigated catheters may deliver various types of fluid to the patient, including, for example, medications, therapeutic fluids, and even cooling fluids for certain procedures wherein heat is generated within targeted areas of the body.

For example, ablation catheters are sometimes used to perform ablation procedures to treat certain conditions of a patient. A patient experiencing arrhythmia, for example, may benefit from ablation to prevent irregular heart beats caused by arrhythmogenic electrical signals generated in cardiac tissues. By ablating or altering cardiac tissues that generate such unintended electrical signals the irregular heart beats may be stopped. Ablation catheters are known, and may include one or more ablation electrodes supplying RF (radiofrequency) energy to targeted tissue. With the aid of sensing and mapping tools that are also known, an electrophysiologist can determine a region of tissue in the body, such as cardiac tissue, that may benefit from ablation.

Once tissue is targeted for ablation, a catheter tip having one or more ablation electrodes may be positioned over the targeted tissue. The ablation electrodes may deliver RF energy, for example, supplied from a generator, to create sufficient heat to damage the targeted tissue. By damaging and scarring the targeted tissue, aberrant electrical signal generation or transmission may be interrupted. In some instances irrigation features may be provided in ablation catheters to supply cooling fluid in the vicinity of the ablation electrodes to prevent overheating of tissue and/or the ablation electrodes. There are typically two classes of irrigated catheter devices, open and closed ablation catheters. Closed ablation catheters typically circulate a cooling fluid within the inner cavity of the ablation catheter tip. Open ablation catheters, on the other hand, use the inner cavity of the ablation catheter tip as a manifold to distribute saline solution, or other irrigation fluids known to those skilled in the art, to one or more passageways leading to an orifice. This lowers the temperature of the ablation catheter tip by bringing the outer surface of the ablation electrode in contact with the cool irrigation fluid and dilute the blood around the electrode to prevent blood coagulation.

<CIT> relates to a recording and ablation catheter system to create continuous linear lesions wherein a catheter does not include both elusion holes and ducts.

<CIT> relates to ablation electrode catheters with irrigation capabilities for electrically mapping a body part or deliver therapy to a body part.

<CIT> relates to intravascular catheters having ring electrodes position at a distal end of the catheter to perform an ablation procedure.

<CIT> relates to an ablation catheter including a shaft supporting one or more partly or completely exposed braided electrodes that may be positioned against a target tissue to ablate the tissue.

<CIT> relates to a catheter including a sensor array that measures temperatures of adjacent tissue along the length of the virtual electrode section of a catheter designed with a virtual electrode structure for creating a linear lesion.

In accordance with an aspect of the present disclosure an irrigated catheter ablation apparatus comprises an elongated body having a distal end, a proximal end, and at least one fluid lumen extending longitudinally therein; and a plurality of segmented ablation electrodes on a distal portion of the elongated body. The plurality of segmented ablation electrodes are spaced from the proximal end and from the distal end of the elongated body by electrically nonconductive segments. The plurality of segmented ablation electrodes are spaced from each other longitudinally by electrically nonconductive segments. For each segmented ablation electrode that is longitudinally disposed next to one of the electrically nonconductive segments, an edge is formed between an electrode end of the segmented ablation electrode and a nonconductive segment end of the electrically nonconductive segment. A plurality of elution holes are disposed adjacent to the edges which are between the electrode ends of the segmented ablation electrodes and the nonconductive segment ends of the electrically nonconductive segments. A plurality of ducts establish fluid communication between the elution holes and the at least one fluid lumen.

In some embodiments, the plurality of elution holes may be disposed in the plurality of electrically nonconductive segments. The plurality of elution holes may be disposed in the plurality of segmented ablation electrodes. The plurality of segmented ablation electrodes may include at least one of a coil ring electrode having gaps in a coil to permit fluid flow therethrough or a ring electrode having gaps cut into the ring electrode to permit fluid flow therethrough. For each of the edges, at least one of the elution holes is disposed adjacent the edge. For each of the edges, more than one of the elution holes are spaced around a circumference adjacent the edge.

In specific embodiments, a tip electrode is disposed at the distal end of the elongated body. The tip electrode has a proximal end which meets a nonconductive segment end of one of the electrically nonconductive segments at a tip electrode edge. At least one tip electrode edge elution hole is disposed adjacent to the tip electrode edge and being in fluid communication with the at least one fluid lumen. The tip electrode may be an ablation tip electrode. The at least one tip electrode edge elution hole is disposed in the tip electrode. At least some of the ducts are substantially perpendicular to the at least one fluid lumen. The distal portion of the elongated body includes a material which is preformed into a substantially closed loop having the plurality of longitudinally spaced segmented ablation electrodes and the electrically nonconductive segments.

In some embodiments, one or more conducting wires coupled with and supplying RF energy to the plurality of segmented ablation electrodes, the RF energy being one of unipolar RF energy or bipolar RF energy. One or more conducting wires are coupled with the plurality of segmented ablation electrodes. An energy source supplies energy via the one or more conducting wires to the plurality of segmented ablation electrodes. A controller is configured to control the energy source to supply energy to the plurality of segmented ablation electrodes in one of an independent manner, a sequential manner, or a simultaneous manner.

In specific embodiments, a plurality of temperature sensors are disposed on and in contact with the plurality of segmented ablation electrodes at the electrode ends. The temperature sensors each substantially abut the edge between one of the electrode ends of the segmented ablation electrodes and one of the nonconductive segment ends of the electrically nonconductive segments. In another embodiment, each of a plurality of temperature sensors is disposed on and in contact with a respective segmented ablation electrode at a location situated between the electrode ends. A controller is configured to control the energy source to supply energy to the plurality of segmented ablation electrodes based on signals received from the plurality of temperature sensors so as to control temperatures of the plurality of segmented ablation electrodes.

In accordance with another aspect of the disclosure, a method of ablating tissue with an irrigated catheter comprises directing fluid through a plurality of elution holes disposed adjacent to the edges which are between the electrode ends of the segmented ablation electrodes and the nonconductive segment ends of the electrically nonconductive segments; and supplying energy to the plurality of segmented ablation electrodes to ablate tissue.

In some embodiments, the distal portion of the elongated body includes a material which is preformed into a substantially closed loop having the plurality of longitudinally spaced segmented ablation electrodes and the electrically nonconductive segments. The substantially closed loop is placed around at least one vessel ostium in a chamber of a patient to ablate the tissue on a chamber wall of the chamber around the at least one vessel ostium. The at least one vessel ostium comprises at least one pulmonary vein. The substantially closed loop may be placed within a vessel of a patient to denervate nerves within and around a vessel wall of the vessel. Denervation is defined herein as partially or totally blocking nerve conduction. Denervation may be achieved by stimulating, or overstimulating, or ablating the nerves. The vessel comprises a renal artery or a renal vein.

These and other features and advantages of the present invention will become apparent to those of ordinary skill in the art in view of the following detailed description of the specific embodiments.

In the following detailed description of the invention, reference is made to the accompanying drawings which form a part of the disclosure, and in which are shown by way of illustration, and not of limitation, exemplary embodiments by which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. Reference in the specification to "one embodiment", "this embodiment", or "these embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and the appearances of these phrases in various places in the specification are not necessarily all referring to the same embodiment. Additionally, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details may not all be needed to practice the present invention. In other circumstances, well-known structures, materials, circuits, processes and interfaces have not been described in detail, and/or may be illustrated in block diagram form, so as to not unnecessarily obscure the present invention.

In the following description, relative orientation and placement terminology, such as the terms horizontal, vertical, left, right, top and bottom, is used. It will be appreciated that these terms refer to relative directions and placement in a two dimensional layout with respect to a given orientation of the layout. For a different orientation of the layout, different relative orientation and placement terms may be used to describe the same objects or operations.

Exemplary embodiments of the invention, as will be described in greater detail below, provide apparatuses for ablation or denervation using an irrigated catheter device with multiple segmented ablation segments. Methods for ablating tissue using the irrigated catheter of the present invention are not explicitly recited by the wording of the claims, but are considered as useful for understanding the invention.

<FIG> is an elevational view of a distal portion of an irrigated ablation catheter <NUM> according to an embodiment of the present invention. The catheter <NUM> has an elongated body with a proximal end <NUM> (see <FIG>), a distal end <NUM>, and at least one fluid lumen <NUM> extending longitudinally therein. A tip electrode <NUM> is disposed at the distal end <NUM>. The tip electode <NUM> may be an ablation tip electrode. The tip electrode <NUM> has irrigation holes <NUM> which are in fluid communication with the fluid lumen <NUM>. In the distal portion, a plurality of segmented ablation electrodes <NUM> are spaced from the proximal end and the distal end <NUM> by electrically nonconductive segments <NUM>, and they are spaced from each other longitudinally by electrically nonconductive segments <NUM>. The electrically nonconductive segments <NUM> may be made of a thermoplastic material. The segmented ablation electrodes <NUM> may be solid rings of a conductive material such as platinum, which are pressure fitted about the elongated body. For each segmented ablation electrode <NUM> that is longitudinally disposed next to one of the electrically nonconductive segments <NUM>, an edge <NUM> is formed between an electrode end of the segmented ablation electrode <NUM> and a nonconductive segment end of the electrically nonconductive segment <NUM>. A plurality of elution holes <NUM> are disposed adjacent to the edges <NUM>. As used herein, "adjacent" to the edge <NUM> means very near or substantially abutting the edge <NUM>, such that the distance between a specific elution hole <NUM> and the edge <NUM> to which it is "adjacent" is at least an order of magnitude smaller than the distance between that elution hole <NUM> and the next edge <NUM> or the distal end <NUM> or the proximal end of the elongated body. A plurality of ducts <NUM> establish fluid communication between the elution holes <NUM> and the fluid lumen <NUM>. The tip electrode <NUM> has a proximal end which meets a nonconductive segment end of one of the electrically nonconductive segments <NUM> at a tip electrode edge <NUM>. It is advantageous to be able to ablate with multiple irrigated electrodes <NUM> and tip electrode <NUM> to reduce the time needed to produce the ablation line on the tissue as compared to moving or dragging an ablation tip along the tissue.

In <FIG>, the elution holes <NUM> are disposed in the electrically nonconductive segments <NUM>. For each of the edges <NUM>, at least one of the elution holes <NUM> is disposed adjacent the edge <NUM>. In <FIG>, multiple (e.g., four) elution holes <NUM> are spaced around a circumference adjacent the edge <NUM>. The ducts <NUM> may be substantially perpendicular to the fluid lumen <NUM>, as seen in <FIG>. In alternative embodiments, the plurality of elution holes are disposed in the segmented ablation electrodes <NUM> or in both the segmented ablation electrodes <NUM> and the electrically nonconductive segments <NUM>.

<FIG> shows a distal portion of another irrigated ablation catheter <NUM> which is similar to the catheter <NUM> of <FIG>. In <FIG>, the tip electrode <NUM> has a proximal end which meets a nonconductive segment end of one of the electrically nonconductive segments <NUM> at a tip electrode edge <NUM>. At least one tip electrode edge elution hole <NUM> is disposed adjacent to the tip electrode edge <NUM> and is in fluid communication with the fluid lumen <NUM> (see <FIG>). In <FIG>, the tip electrode edge elution holes <NUM> are spaced around a circumference adjacent the tip electrode edge <NUM>, and are disposed in the tip electrode <NUM>. In alternative embodiments, the tip electrode edge elution holes <NUM> may be disposed in the electrically nonconductive segment <NUM>.

<FIG> shows a distal portion of another irrigated ablation catheter <NUM> which is similar to the catheter <NUM> of <FIG> but does not have a tip electrode at the distal end <NUM>.

<FIG> shows a distal portion of another irrigated ablation catheter <NUM> which is similar to the catheter <NUM> of <FIG>. A tip electrode <NUM> is disposed at the distal end <NUM> and has irrigation holes <NUM>. The segmented ablation electrodes in <FIG> are coil ring electrodes <NUM> which are spaced from the proximal end and the distal end <NUM> by electrically nonconductive segments <NUM>, and the electrodes <NUM> are spaced from each other longitudinally by electrically nonconductive segments <NUM>. An edge <NUM> is formed between an electrode end of the segmented ablation electrode <NUM> and a nonconductive segment end of the electrically nonconductive segment <NUM>. The plurality of elution holes are disposed in the coil ring electrodes <NUM>, which have gaps in the coil to allow fluid to flow out. For example, elution holes in fluid communication with the fluid lumen <NUM> via the ducts <NUM> (see <FIG>) are provided in a portion of the elongated body underneath the coil ring electrodes <NUM>, and the fluid flows through the elution holes and the gaps in the coil.

<FIG> shows a distal portion of another irrigated ablation catheter <NUM> which is similar to the catheter <NUM> of <FIG> but has a tip electrode <NUM> at the distal end <NUM>. Instead of the coil ring electrodes <NUM>, the catheter <NUM> includes flexible ring electrodes <NUM> having gaps cut into a cylindrical sheet to allow fluid to flow out. One of the flexible ring electrodes <NUM> also forms the tip electrode <NUM>. For example, elution holes in fluid communication with the fluid lumen <NUM> via the ducts <NUM> (see <FIG>) are provided in a portion of the elongated body underneath the flexible ring electrodes <NUM>, and the fluid flows through the elution holes and the gaps in the electrodes <NUM>. The gaps may be laser cut into the cylindrical sheets of the electrodes <NUM>. The flexible ring electrodes <NUM> are spaced from the proximal end of the elongated body by an electrically nonconductive segment <NUM>, and the electrodes <NUM> are spaced from each other longitudinally by electrically nonconductive segments <NUM>. An edge <NUM> is formed between an electrode end of the segmented ablation electrode <NUM> and a nonconductive segment end of the electrically nonconductive segment <NUM>.

In <FIG>, the gaps are elongated gaps in a corrugated pattern. As used herein, an elongated gap preferably has a length that is at least about <NUM> times the width of the gap, more preferably at least about <NUM> times, and most preferably at least about <NUM> times. A variety of gap patterns are possible. The gaps may be linear or curvilinear instead of corrugated. The gaps may be spiral gaps that extend in a helical pattern in the longitudinal direction or transverse gaps that are spaced from each other in the longitudinal direction. A transverse gap may extend less than <NUM> degrees or may extend the full <NUM> degrees. For a transverse gap that extends the full <NUM> degrees, some type of additional supporting structure is required to connect the severed-pieces together. For example, a biasing element such as an inner coil may be provided within the elongated body. Examples of flexible ring electrodes with elongated gaps can be found, for example, in <CIT> and <CIT>, the entire disclosures of which are incorporated herein by reference.

<FIG> is a transverse sectional view of a distal portion of an irrigated ablation catheter, which may be any of the catheters shown in <FIG>. <FIG> shows four ducts <NUM> connected to the fluid lumen <NUM>. Additional lumens are provided for conducting wires <NUM> for supplying energy to the electrodes, one or more preshaping wires <NUM> made of a material such as Nitinol to provide a preformed shape for the distal portion of the catheter, one or more activation wires <NUM> for manipulating the distal portion (e.g., bidirectional bending and/or loop size adjusting), and a plurality of temperature sensor lines <NUM>. The multiple lumens can be formed within a single extruded tubing to separate the fluid lumen <NUM> from the other lumens that house the various components described above.

<FIG> is a longitudinal sectional view of a distal portion of an irrigated ablation catheter showing the fluid lumen <NUM>, conducting wires <NUM>, preshaping wires <NUM>, activation wires <NUM>, and temperature sensor lines <NUM>.

<FIG> is a longitudinal sectional view of a distal portion of an irrigated ablation catheter showing temperature sensors <NUM> located at edges <NUM>, <NUM> of an electrode <NUM>. For clarity, elution holes and corresponding ducts are omitted in <FIG>. The edges <NUM>, <NUM> are where the electrode <NUM> abuts the underlying, electrically nonconductive support body <NUM>. The temperature sensors <NUM> are disposed on and in contact with the segmented ablation electrode <NUM> at the electrode ends substantially abutting the edges <NUM>, <NUM>. For RF ablation, RF current densities are high at the edges <NUM>, <NUM>, because the electrically conductivity is discontinuous at the edges <NUM>, <NUM>. The resulting rise in current density at the electrode edges <NUM>, <NUM> generates localized regions of increased power density and hence regions of higher temperatures. Therefore, temperature sensing and irrigation fluid cooling at the edges <NUM>, <NUM> are desirable. In another embodiment, where a single temperature sensor <NUM> is used for an ablation electrode <NUM>, the single temperature sensor <NUM> is disposed on and in contact with the ablation electrode <NUM> at a location situated between the edges <NUM> and <NUM>. A temperature sensor may also be provided at the tip electrode (<NUM>, <NUM>, <NUM>, <NUM>) adjacent the tip electrode edge (<NUM>, <NUM>, <NUM>) in the catheter (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) of <FIG>, <FIG>, <FIG>, <FIG>, or <FIG>.

<FIG> is a perspective view of a distal portion of an irrigated ablation catheter having a preformed loop shape. For example, the one or more preshaping wires <NUM> includes a material such as Nitinol so that the distal portion is preformed into a substantially closed loop with the distal tip <NUM> having a plurality of longitudinally spaced segmented ablation electrodes <NUM> and electrically nonconductive segments <NUM>.

<FIG> and <FIG> are elevational views of an irrigated ablation catheter <NUM> showing a handle <NUM> connected to a proximal end <NUM> of the elongated body <NUM> for manipulating the shape of a distal portion of the catheter <NUM> near the distal end <NUM>. In <FIG>, the distal portion of the catheter <NUM> includes a loop <NUM> having segmented ablation electrodes (see <FIG>). The handle <NUM> includes a first roller <NUM> for changing the size of the loop <NUM>, and a second set of rollers or sliders <NUM> for bidirectional bending of the elongated body <NUM>.

<FIG> is a system installation diagram of an RF ablation system with an irrigated ablation catheter. The system includes a catheter <NUM> with multiple electrodes, a connecting cable <NUM>, an RF generator <NUM>, an EKG connecting cable <NUM>, and a DIP (Dispersive Indifferent Patch) electrode device <NUM> that is connected to the RF generator <NUM> through an isolated patient connector <NUM>. The DIP electrode device <NUM> is placed under a patient, during an ablation procedure, to provide a closed-loop circuit of the RF energy delivery system. The catheter <NUM> has a plurality of electrodes <NUM> and a plurality of temperature sensing elements. Each temperature sensing element is located at the proximity of each of the electrodes <NUM>. The catheter <NUM> is connected to the RF generator <NUM> through the connecting cable <NUM>. Each of the insulated temperature wires and the conducting wires of the catheter <NUM> are secured to a connector <NUM> contact pin of the catheter <NUM>. Therefore, the measured temperature data from each of the multiple electrodes is relayed to a control mechanism located in the CPU board <NUM> (<FIG>) of the RF generator <NUM>. In the meantime, the RF energy output is delivered through each of the conducting wires to a respective individual electrode on the catheter <NUM>. The control mechanism of the CPU board <NUM> also controls the operation of an irrigation pump <NUM> which is used to pump irrigation fluid to the irrigated catheter <NUM>.

The EKG connecting cable <NUM> is used to transmit the intracardiac electrical signal to an external EKG monitor <NUM> (<FIG>) to display the intracardiac electrical signal sensed and returned by each of the electrodes <NUM>. At the back panel of the RF generator <NUM>, there are a power supply port <NUM>, a data output port <NUM>, and a pump port <NUM>. An optional footswitch <NUM> is also provided for the user's convenience. Either the footswitch <NUM> or a button <NUM> on the front panel of the RF generator <NUM> can be used to start and stop the RF energy delivery.

<FIG> is a block diagram of the RF ablation system of <FIG>, to provide RF energy delivery through an RF splitter to each of the multiple electrodes of the ablation catheter <NUM>. The power supply source <NUM> is connected to the RF generator <NUM> having the RF board <NUM> and the CPU board <NUM>. A software program becomes an integral portion of the CPU board <NUM>. A catheter <NUM> that has multiple electrodes has a plurality of temperature sensing elements <NUM>. Each temperature sensing element <NUM> is associated with one of the electrodes <NUM>. The measured temperature data is relayed to the software program inside the CPU board <NUM>. The data from the CPU board <NUM>, such as power, temperature, impedance, and time, is then displayed via a display board <NUM>. The command or instruction is issued from the CPU board <NUM> to the RF board <NUM> to control the RF energy output. An RF splitter <NUM> is employed to split the RF energy in order to deliver it to one or more of the conducting wires, wherefrom thereafter the RF energy output is relayed to the corresponding electrode or electrodes. A digital control signal <NUM> from the CPU board <NUM> to the RF splitter <NUM> controls the manner in which the RF energy is delivered to the one or more conducting wires. The RF energy may be delivered in an independent manner, or a sequential manner, or a simultaneous manner. The conducting wires which deliver the RF energy to the multiple electrodes of the catheter <NUM> also carry a low-frequency EKG signal which is sensed and returned by each of the multiple electrodes. A low-pass filter <NUM> is used to allow only the EKG signal to pass to the EKG monitor <NUM> for real-time display. The control mechanism of the catheter system only allows ablation or denervation when the real-time cardiac electrical signal assures that the catheter is still at a proper location. Data can be stored in the CPU <NUM> or outputted through an RS232 port <NUM> to an external computer <NUM> for data analysis. Data may also be outputted to an analog output port <NUM>. The CPU board <NUM> sends a control signal via the pump port <NUM> to the pump <NUM> to control the operation of the pump <NUM>, such as, for example, the flow rate of the fluid delivered by the pump <NUM> to the irrigated catheter <NUM>.

<FIG> is a flow diagram of the software program for the RF ablation system of <FIG>. The major steps in the software program include: "Set ablation mode" block <NUM>, "Set parameters" block <NUM>, "Turn pump on" block <NUM>, "Start ablation" block <NUM>, "Is temp within limit?" block <NUM> and "Ablate until time is up" block <NUM>. The ablation mode <NUM> includes one of the modes: a simultaneous mode, a sequential mode, a random-order mode, or a combination of the above. The "Set parameters" block <NUM> includes setting the power limit, the temperature limit, the impedance limit, and the time limit. The power limit <NUM> is initially set at a relatively low value for safety reasons. An example would be to set the initial power limit at <NUM> watts. The power limit can be raised in appropriate increments until a final power limit of the RF generator is reached. One example for the final power limit would be <NUM> watts. The temperature limit is set for a range, which is appropriate for the ablative lesion. One example would be to set the ablation temperature limit as <NUM>±<NUM>. The "time is up" is a predetermined time duration for ablating any of the electrodes. One example would be to set the time limit for electrode no. <NUM> as <NUM> seconds. More details of operating the system can be found in <CIT>, which is incorporated herein by reference in its entirety. When the pump is turned on (block <NUM>), the pump flow rate is set to low. When the ablation is started (block <NUM>), the pump flow rate is automatically changed to high. When the ablation is complete, the pump flow rate is automatically changed to low.

The RF energy may be unipolar RF energy or bipolar RF energy depending on the configuration. The control mechanism or controller on the CPU board <NUM> of the RF generator <NUM> is configured to control the energy source to supply energy to the plurality of segmented ablation electrodes in an independent manner (control energy to each electrode independently), a sequential manner (control energy to the electrodes in a preset sequence), or a simultaneous manner (control energy to the electrodes simultaneously). The controller may be configured to control the energy source to supply energy to the segmented ablation electrodes based on signals received from the temperature sensors so as to control temperatures of the segmented ablation electrodes. Controlling the temperatures of the electrodes by regulating the supply of energy to the electrodes is also described, for instance, in <CIT>, which is incorporated herein by reference in its entirety.

<FIG> shows schematic diagrams of ablation patterns around at least one vessel ostium <NUM>. The loop <NUM> of the catheter in <FIG> can be placed around at least one vessel ostium in a chamber of a patient to ablate the tissue on a chamber wall of the chamber around the at least one vessel ostium. <FIG> shows an ablation pattern around each vessel ostium <NUM>. <FIG> shows an ablation pattern around two vessel ostia <NUM>. <FIG> shows an ablation pattern around four vessel ostia <NUM>. Each vessel ostium may be a pulmonary vein for pulmonary vein isolation. See, e.g., <CIT>, which is incorporated herein by reference in its entirety. Another application is for ablating renal sympathetic nerves in therapeutic renal sympathetic denervation to achieve reductions of blood pressure in patients suffering from renal sympathetic hyperactivity associated with hypertension and its progression. See, e.g., <NPL> at www. The catheter will be sized differently for ablating or denervating nerves located within and around different vessels and walls. For example, the size of the catheter for ablating renal sympathetic nerves is typically smaller than that for ablating around a pulmonary vein.

In the description, numerous details are set forth for purposes of explanation in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that not all of these specific details are required in order to practice the present invention. It is also noted that the catheter of the present invention may be used in a process, which is usually depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged.

Claim 1:
An irrigated catheter ablation apparatus comprising:
an elongated body (<NUM>) comprising a proximal end (<NUM>) and a distal portion including a distal end (<NUM>), the elongated body (<NUM>) having at least one fluid lumen (<NUM>) extending longitudinally therein;
a plurality of segmented ablation electrodes (<NUM>) positioned at the distal portion;
at least one electrically nonconductive segment (<NUM>), wherein adjacent segmented ablation electrodes (<NUM>) of the plurality of segmented ablation electrodes (<NUM>) are spaced from each other longitudinally by a respective one of the at least one electrically nonconductive segment (<NUM>);
a plurality of elution holes (<NUM>) disposed in the at least one electrically nonconductive segment (<NUM>) adjacent to an edge (<NUM>), wherein for each segmented ablation electrode (<NUM>) that is longitudinally disposed next to one of the electrically nonconductive segments (<NUM>), the edge (<NUM>) is formed between an electrode end of the segmented ablation electrode (<NUM>) and a nonconductive segment end of the nonconductive segment (<NUM>); and
a plurality of ducts (<NUM>) establishing fluid communication between the plurality of elution holes (<NUM>) and the at least one fluid lumen (<NUM>).