Patent Application
20140088584
The disclosure generally pertains to percutaneous and intravascular devices for nerve modulation and/or ablation.
BACKGROUND
Certain treatments require the temporary or permanent interruption or modification of select nerve function. One example treatment is renal nerve ablation which is sometimes used to treat conditions related to congestive heart failure. The kidneys produce a sympathetic response to congestive heart failure, which, among other effects, increases the undesired retention of water and/or sodium. Ablating some of the nerves running to the kidneys may reduce or eliminate this sympathetic function, which may provide a corresponding reduction in the associated undesired symptoms.
Many body tissues such as nerves, including renal nerves, brain tissue, cardiac tissue and the tissue of other body organs are in close proximity to blood vessels or other body cavities and thus can be accessed percutaneously or intravascularly through the walls of the blood vessels. In some instances, it may be desirable to ablate perivascular nerves using a radio frequency (RF) electrode. In other instances, the perivascular nerves may be ablated by other means including application of thermal, ultrasonic, laser, microwave, and other related energy sources to the vessel wall.
In treatments involving perivascular nerves such as renal nerves, treatment methods employing such energy sources have tended to apply the energy as a generally circumferential ring to ensure that the nerves are modulated. However, such a treatment may result in thermal injury to the vessel wall near the electrode and other undesirable side effects such as, but not limited to, blood damage, clotting, weakened vessel wall, vessel thrombus, and/or protein fouling of the electrode.
It is therefore desirable to provide for alternative systems and methods for tissue treatment such as intravascular nerve modulation which distributes ablation or modulation sites along and around the vessel or other body cavity.
Some embodiments of the disclosure are directed to a balloon catheter configured for tissue modulation such as nerve modulation and/or ablation. The balloon catheter includes an inflatable balloon at or proximate a distal end of the device. The wall of the balloon is constructed so as to include areas for transmitting therapeutic energy from the balloon into body tissue. These areas may be, for example, RF electrodes located on the surface of the balloon or ionically permeable windows for permitting the transmission of ionic energy from within the balloon lumen. Fluid may be supplied to the balloon through a plurality of fluid inlet ports and may be evacuated from the balloon through one (or more) fluid outlet ports. The plurality of fluid inlet ports direct the inflation fluid against the interior of the balloon wall. The plurality of fluid inlet ports may be configured to direct the fluid directly against the areas for transmitting therapeutic energy or may be configured to direct the fluid against areas of the interior of the balloon wall other than those areas for transmitting therapeutic energy.
The above summary of some example embodiments is not intended to describe each disclosed embodiment or every implementation of the disclosure.
The disclosure may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which:
While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.
The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The drawings, which are not necessarily to scale, are not intended to limit the scope of the claimed invention. The detailed description and drawings illustrate example embodiments of the claimed invention.
All numbers are herein assumed to be modified by the term “about.” The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).
As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include the plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described unless clearly stated to the contrary.
While the devices and methods described herein are discussed relative to renal nerve modulation through a blood vessel wall, it is contemplated that the devices and methods may be used in other applications where nerve modulation and/or ablation are desired. The term modulation refers to ablation and other techniques that may permanently alter the function of affected nerves and other tissue such as brain tissue or cardiac tissue. When multiple ablations are desirable, they may be performed sequentially by a single ablation device. In some embodiments, one ablation catheter can perform multiple treatments.
The control and power element 18 may include monitoring elements to monitor and control parameters such as power, temperature, time, voltage, pulse size, impedance and/or shape and other suitable parameters, with sensors mounted along renal nerve modulation device 12, as well as suitable controls for performing the desired procedure. In some embodiments, the power element 18 may control a radio frequency (RF) electrode. The electrode may be configured to operate at a frequency of approximately 460 kHz. It is contemplated that any desired frequency in the RF range may be used, for example, from 450-500 kHz. It is further contemplated that other ablation devices may be used as desired, for example, but not limited to resistance heating, ultrasound, microwave, and laser devices and these devices may require that power be supplied by the power element 18 in a different form.
A cross-sectional view of the central shaft 35 and outer shaft 34 at section line 3 in
A cross-sectional view of the shaft 34 of the renal nerve modulation device 12 at section line 4 in
Balloon 22 is shown in cross-section as having a first layer 25 and a second layer 23. A window 28 is formed in balloon 22 by the absence of second layer 23. First layer 25 is preferably made from an ionically permeable material. One suitable material is, for example, a hydrophilic polyurethane. The second layer 23 is preferably made from an electrically non-ionically permeable polymer such as a non-hydrophilic polyurethane, Pebax, nylon, polyester or block-copolymer.
In the embodiment illustrated in
In use, a renal ablation system such as system 10 is provided. The system may be used with a standard guide catheter such as a 6 French guide catheter. The balloon and in particular the hydrophilic or tecophilic material may be hydrated as part of the preparatory steps. Hydration may be effected by soaking the balloon in a saline solution. A one minute, five minute, or other suitable soak may be beneficial. Then the renal nerve modulation device 12 may then be introduced percutaneously as is conventional in the intravascular medical device arts by using a guide catheter and/or a guide wire. For example, a guide wire such as a 0.014″ diameter guidewire may be introduced percutaneously through a femoral artery and navigated to a renal artery using standard radiographic techniques. In some embodiments, a delivery sheath 14 may be introduced over the guide wire and the guide wire may be withdrawn, and the renal nerve modulation device 12 may be then introduced through the delivery sheath. In other embodiments, the renal nerve modulation device 12 may be introduced over the guidewire, or the system 10, including a delivery sheath 14 may be introduced over a guidewire. In embodiments involving a delivery sheath 14, the renal nerve modulation device 12 may be delivered distally from the distal end of the delivery sheath 14 into position, or the delivery sheath may be withdrawn proximally to expose the distal portion of renal nerve modulation device 12. A conductive fluid 26 is introduced into the balloon through fluid inlet ports 32 and may expand the balloon to the desired size. The balloon expansion may be monitored indirectly by monitoring the volume, or flow rate, of conductive fluid introduced into the system or may be monitored through radiographic or other conventional means. Once the balloon is expanded to the desired size, the conductive fluid 26 may be circulated within the balloon by continuing to introduce the fluid through the fluid inlet ports 32 while withdrawing fluid from the balloon through the fluid outlet 30. The rate of circulation of the fluid may be between 2 and 20 ml/min, between 3 and 15 ml/min, between 5 and 75 ml/min or other desired rate of circulation.
The balloon may be kept at or near a desired pressure such as a pressure of between 0.25 and 6 atmospheres, between 1.5 and 4 atmospheres, between 2.5 and 3.5 atmospheres, or other desired pressure. The electrode(s) is then activated by supplying energy. The energy may be supplied at 400-500 Hz and at between 0.05 and 1 amp. The energy is transmitted to the blood vessel wall to modulate or ablate the surrounding tissue. The progress of the treatment may be monitored by monitoring changes in impedance through the electrode. Other measurements such as pressure and/or temperature measurements may be conducted during the procedure as desired. The circulation of the conductive fluid 26 may mitigate the temperature rise of the tissue or the blood vessel 48 in contact with the windows 28. The electrode 24 is preferably activated for an effective length of time, such as 1 minute or 2 minutes. Once the procedure is finished at a particular location, the balloon 22 may be partially or wholly deflated and moved to a different location such as the other renal artery, and the procedure may be repeated at another location as desired using conventional delivery and repositioning techniques. Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and principles of this disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth hereinabove. All publications and patents are herein incorporated by reference to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference.
This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application Ser. No. 61/705,968, filed Sep. 26, 2012, the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61705968 | Sep 2012 | US |
