Patent Application
20200197083
The present invention relates generally to a system for applying energy for the treatment of tissue, and more particularly to a cooled radiofrequency probe having a curved or bendable tip and small diameter for improved steerability.
Lower back injuries and chronic joint pain are major health problems resulting not only in debilitating conditions for the patient, but also in the consumption of a large proportion of funds allocated for health care, social assistance and disability programs. In the lower back, disc abnormalities and pain may result from trauma, repetitive use in the workplace, metabolic disorders, inherited proclivity, and/or aging. The existence of adjacent nerve structures and innervation of the disc are very important issues in respect to patient treatment for back pain. In joints, osteoarthritis is the most common form of arthritis pain and occurs when the protective cartilage on the ends of bones wears down over time.
A minimally invasive technique of delivering high-frequency electrical current has been shown to relieve localized pain in many patients. Generally, the high-frequency current used for such procedures is in the radiofrequency (RF) range, i.e. between 100 kHz and 1 GHz and more specifically between 300-600 kHz. The RF electrical current is typically delivered from a generator via connected electrodes that are placed in a patient's body, in a region of tissue that contains a neural structure suspected of transmitting pain signals to the brain. The electrodes generally include an insulated shaft with an exposed conductive tip to deliver the radiofrequency electrical current. Tissue resistance to the current causes heating of tissue adjacent resulting in the coagulation of cells (at a temperature of approximately 45° C. for small unmyelinated nerve structures) and the formation of a lesion that effectively denervates the neural structure in question. Denervation refers to a procedure whereby the ability of a neural structure to transmit signals is affected in some way and usually results in the complete inability of a neural structure to transmit signals, thus removing the pain sensations. This procedure may be done in a monopolar mode where a second dispersive electrode with a large surface area is placed on the surface of a patient's body to complete the circuit, or in a bipolar mode where a second radiofrequency electrode is placed at the treatment site. In a bipolar procedure, the current is preferentially concentrated between the two electrodes.
To extend the size of a lesion, radiofrequency treatment may be applied in conjunction with a cooling mechanism, whereby a cooling means is used to reduce the temperature of the electrode-tissue interface, allowing more energy or power to be applied without causing an unwanted increase in local tissue temperature that can result in tissue desiccation, charring, or steam formation. The application of more energy or power allows regions of tissue further away from the energy delivery device to reach a temperature at which a lesion can form, thus increasing the size/volume of the lesion.
The treatment of pain using high-frequency electrical current has been applied successfully to various regions of patients' bodies suspected of contributing to chronic pain sensations. For example, with respect to back pain, which affects millions of individuals every year, high-frequency electrical treatment has been applied to several tissues, including intervertebral discs, facet joints, sacroiliac joints as well as the vertebrae themselves (in a process known as intraosseous denervation). In addition to creating lesions in neural structures, application of radiofrequency energy has also been used to treat tumors throughout the body. Further, with respect to knee pain, which also affects millions of individuals every year, high-frequency electrical treatment has been applied to several tissues, including, for example, the ligaments, muscles, tendons, and menisci.
Due to the large volume lesions generated by cooled radiofrequency probe procedures, care must be taken when treating sensitive locations, particularly around areas that cannot sustain significant collateral ablative damage. Existing cooled radiofrequency probes typically have a 17 gauge diameter, which is very large in diameter in comparison to non-cooled radiofrequency ablation probes and other nerve block needles, which may have a diameter between 18 gauge and 22 gauge, for example. As a result, the existing cooled radiofrequency probes result in puncture site and procedural pain. Additionally, the existing 17 gauge cooled radiofrequency probes have reduced steerability of the needle in tissue in comparison to non-cooled radiofrequency ablation probes and other nerve block needles having a smaller diameter. As such, existing 17 gauge cooled radiofrequency probes are more difficult to avoid obstructions, such as bones, in the patient's tissue and must be repeatedly withdrawn from the tissue and re-inserted in the direction to avoid obstructions, causing additional potential tissue damage.
Consequently, there is a need for a cooled radiofrequency ablation probe having optimized shape and size to improve the steerability of the probe needle in tissue. Moreover, a cooled radiofrequency probe that has a curved or bendable tip and/or reduced diameter in order to reduce trauma at the puncture site and pain resulting from the procedure would be useful.
The present invention provides cooled radiofrequency ablation probe extending along a longitudinal axis. The cooled radiofrequency ablation probe includes an electrocap assembly having an elongated member having a body, a proximal end configured to interface with a probe handle, and a thermally and electrically conductive distal end configured to deliver electrical or radiofrequency energy to a patient's tissue. The elongated member houses at least one cooling fluid tubing within the length of the body and a thermocouple hypotube within the length of the elongated member. The body and the proximal end of the elongated member are straight relative to the longitudinal axis. The distal end of the elongated member is curved relative to the longitudinal axis.
In one particular embodiment, the elongated member can have a 20 gauge needle diameter.
In another embodiment, the distal end can be curved at an angle in a range from about 1 degree to about 30 degrees relative to the longitudinal axis.
In yet another embodiment, the body and the proximal end of the elongated member can be electrically insulated. Further, a portion of the elongated member can be not electrically insulated to expose an active tip for delivering electrical or radiofrequency energy.
In one more embodiment, the probe can be capable of creating a lesion in the patient's tissue when electrical or radiofrequency energy is applied, wherein the lesion created by the probe is of approximately the same size as a lesion created by a larger 17 gauge diameter cooled radiofrequency probe under identical temperature and power settings.
The present invention additionally provides a cooled radiofrequency ablation probe including an electrocap assembly having an elongated member having a body, a proximal end configured to interface with a probe handle, and a thermally and electrically conductive distal end configured to deliver electrical or radiofrequency energy to a patient's tissue. The elongated member houses at least one cooling fluid tubing within the length of the body and a thermocouple hypotube within the length of the elongated member. The body and the proximal end of the elongated member are straight. The distal end of the elongated member is configured to flex or bend to improve steerability of the probe in the tissue.
In one particular embodiment, the distal end can include a cut-out section.
In another embodiment, the distal end can include a polymer section.
In yet another embodiment, the distal end can include a curved section. Further, the curved section can be curved at an angle in a range from about 1 degree to about 30 degrees relative to a longitudinal axis of the elongated member.
The present invention additionally provides a cooled radiofrequency ablation delivery kit. The kit includes an introducer having a hollow elongate member, the hollow elongate member having a distal end, a body, and a proximal end, wherein the hollow elongate member is straight from the distal end to the proximal end; a stylet having a piercing surface on a tip of a distal end, wherein the stylet is configured to be inserted through the introducer to create a puncture wound in patient tissue; and a cooled radiofrequency probe extending along a longitudinal axis comprising a distal end configured to bend or flex to improve steerability of the probe in the tissue. The probe is configured to be inserted through the introducer to deliver electrical or radiofrequency energy to the patient tissue via an active tip at a distal end of the probe.
In one particular embodiment, the introducer can be configured to conform to the distal ends of the stylet and the probe, respectively, when the stylet or the probe is inserted through the hollow elongate member.
In yet another embodiment, the distal end of the probe can be curved. Further, the angle of curvature of the curved distal end of the probe can be in a range from about 1 degree to about 30 degrees relative to the longitudinal axis. In one more embodiment, the distal end of the probe can include a cut-out section.
In still another embodiment, the distal end of the probe can include a polymer section.
In a further embodiment, the probe can be longer than the stylet.
In still another embodiment, the stylet and the probe can be formed from a rigid material.
In one more embodiment, the introducer can include a male connector, further wherein each of the stylet and the probe can include female connectors for coupling to the male connector of the introducer.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference will now be made in detail to one or more embodiments of the invention, examples of the invention, examples of which are illustrated in the drawings. Each example and embodiment is provided by way of explanation of the invention, and is not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that the invention include these and other modifications and variations as coming within the scope and spirit of the invention.
Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
For the purposes of this invention, a lesion refers to the region of tissue that has been irreversibly damaged as a result of the application of thermal energy, and the invention is not intended to be limited in this regard. Furthermore, for the purposes of this description, proximal generally indicates that portion of a device or system next to or nearer to a handle of the probe (when the device is in use), while the term distal generally indicates a portion further away from the handle of the probe (when the device is in use).
As used herein, the terms “about,” “approximately,” or “generally,” when used to modify a value, indicates that the value can be raised or lowered by 5% and remain within the disclosed embodiment.
Referring now to the drawings,
As shown in
Referring again to
The distal end 272 of the stylet 270 can extend at an angle θ2 with respect to the longitudinal x axis, as shown in
The distal end 206 of the cooled radiofrequency probe 200 can be curved at an angle θ3 with respect to the longitudinal x axis as shown in
Turning now to
In one embodiment, the curved probe 200 can have a diameter that is narrower than the prior art 17 gauge probe of
The curved probe 200 of the present invention is capable of creating lesions in patient tissue having comparable size to lesions created by a larger diameter, straight 17 gauge cooled radiofrequency probe when provided with the same power and settings from a radiofrequency generator. For example, Table 1 below shows the lesion height and lesion width of 11 sample lesions created by a 20 gauge cooled radiofrequency probe 200 of the present invention at an average power of about 4.83±0.79 watts. The sample lesions created were performed ex vivo in a raw chicken breast.
The mean lesion height of the lesions described in Table 1 was 10.75091 mm with a standard deviation of 1.021454 mm, and the mean lesion width was 10.56818 mm with a standard deviation of 1.097003 mm. The lesions created using the 20 gauge curved cooled radiofrequency probe 200 of the invention are comparable in size to lesions created by a 17 gauge cooled radiofrequency probe. Thus, the 20 gauge curved probe of the present invention significantly improves the steerability of the radiofrequency probe compared to the existing straight 17 gauge diameter probe while delivering the same lesion size for treatment of a patient's tissue.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
