The present disclosure relates to medical methods and apparatus for treating various types of biological cells and tissue by inducing localized hyperthermia or thermal ablation.
Humans and/or animals can suffer from various types of tissue-related illnesses, such as varicose veins, breast cancer, and tumors. One of the approaches in treating these diseases is with thermotherapy. Thermotherapy subjects tissue(s) to temperatures that result in structural modification, damage or destruction of cells that comprise the tissue. One method of thermotherapy, hyperthermia, employs miniscule particles that are capable of converting electromagnetic energy into thermal energy. These particles are delivered to the target tissue and destroy the malignant cells with thermal energy when the particles are immersed in an alternating magnetic field. Thermotherapy may be used in thermal ablation by raising cell or tissue temperature to a point where physical cell destruction occurs. Hereinafter, the term tissue collectively refers to a portion of a body to be treated.
Existing methods of inducing hyperthermia and thermal ablation employ radio frequency (RF) currents, microwave energy, photonic energy, ultrasonic energy and the cauterization to the targeted tissue/cells. In all of these modalities, energy delivery and thermo-regulation are critical parameters since excessive energy absorption may result in unintended and/or collateral damage to adjacent tissue or structures and undesired char formation. Typical shortcomings in some of these technologies include large and non-conforming electrodes or applicators (electrodes and applicators are the devices that delivery energy from a source to the tissue) and complex temperature sensing and controlling schemes.
The bilateral tubal sterilization (TS) is another well known thermotherapy technique. In developed countries, permanent tubal occlusion is most commonly performed using laparoscopy techniques (utilizing a transabdominal approach) where the fallopian tubes are physically occluded using a ring, a clip or electrocauterization. An estimated 700,000 bilateral TS are performed annually in the US and 11 million US women 15-44 years of age rely on TS for contraception. Tubal sterilization has also been shown to be associated with decreased risk of ovarian cancer.
Despite its worldwide use and high efficacy, TS using the transabdominal approach is associated with substantial trauma and discomfort which, in a majority of cases, involves the inconvenience and expense of a hospital stay and carries the risk of complications such as bleeding, infection, bowel perforation and reaction to general anesthesia. A few transcervical tubal occlusion devices have been developed and are steadily gaining acceptance as a viable alternative to transabdominal sterilization techniques.
Available tubal blocking systems depend upon mechanical occlusive techniques, chemically or thermally induced tissue damage and combinations of these techniques. Chemical agents induce tissue damage, which leads to formation of scar tissue to seal the opening of the fallopian tubes. The major drawback to this method is the need for repeated applications. Thermal blocking systems use either heat or cryogenic methods to damage tissue and also induce the formation of scar tissue to seal the opening of the fallopian tubes.
In one embodiment, a material to be injected into target tissue of a body includes: a carrier substrate; a plurality of first particles operative to generate thermal energy in response to an alternating electromagnetic field applied external to the body; and a plurality of second particles, each of the second particles having a core and a coating surrounding the core. The coating is dissolved at a preset temperature by the thermal energy so that the visibility of the core in an external imaging system is affected as the coating is dissolved to expose the core. The variation of the visibility can be used as an indicator to determine if the material has reached the preset temperature.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention because the scope of the invention is best defined by the appended claims.
The carrier substrate 100 may be biocompatible, bio-absorbable, and can be formulated as a liquid, gel, solid, or some permutation thereof, depending on the type of application. The carrier substrate 100 provides additional properties, such as anti-clumping, anesthetic, promotion of flow and coverage, and promotes visualization and other therapeutic agents. The carrier substrate 100, for instance, can be formulated with a polymer such as polyglycolic acid to produce a solid, bio-absorbable implantable. The particles 102, suspending in the carrier substrate 106, may be composed of ferrimagnetic, ferromagnetic, or super-paramagnetic materials. The particles 102 have an average size from 1 nm to 100 μm so as to induce a high specific absorption rate (SAR) in the tissue. The particle coating 104 may be anionic or cationic and include organic or inorganic compounds at a thickness of 1 nm-100 μm, and provide biocompatibility and prevent particle agglomeration. The particle coating 104 may have an additional coating of surfactant.
The material 100 is inherently thermally self-regulating to prevent the temperature of the material from exceeding the designed-in upper temperature limit. For instance, the particles 102 may be formed of a metal alloy with a preset Curie temperature so that the temperature of the material does not go beyond the Curie temperature during operation. The Curie temperature is lower than the threshold temperature to damage healthy cells and higher than the threshold temperature to destroy malignant cells.
The contrast agents 128 serve as a contrast agent and/or to improve visualization under ultrasound, fluoroscopy, MRI and other suitable imaging techniques. For instance, the contrast agents block the passage of X-rays to result in bright areas in a conventional x-ray image, promote the reflection of ultrasonic energy waves back to the source to result in an increase of ultrasonic signal intensity of the area containing the substrate, or alter the relaxation times of the excited spins in the MRI technique thereby to increase or decrease the signal intensity of the area containing the substrate. By use of the visualization/imaging technique with the contrast agent 128, a medical practitioner can easily determine the location of particles within the human body. The contrast agents 128 may be formed of Gadolinium based material, Methylxanthines, or N-acetylcysteine, for instance.
The contrast agents 128 may be coated with contrast agent coating 130 such that at a specific temperature, the coating 130 will release the contrast agent 128 to indicate the target temperature has been achieved as an aid to the operator. Alternatively, the coating 130 may release a secondary substance to inhibit the contrast agent functionality. The sizes of the particles 124 and the particle coating 126 may be in the same ranges as those of the contrast agents 128 and the contrast agent coating 130, respectively.
The therapeutic agents 148 contain chemical compounds that can aid in patient recovery and comfort (i.e. wound healing, pain management). The therapeutic agents 148 and the therapeutic agent coating 150 operate as a drug delivery agent. The therapeutic agent coating 150 will release or activate the therapeutic agents 148 to optimize the therapeutic effect. The therapeutic agents themselves may be heat activated or enhanced by temperatures above 37° C., for instance. The sizes of the particles 148 and the particle coating 146 may be in the same ranges as those of the therapeutic agents 148 and the therapeutic coating 150, respectively.
It should be apparent to those of ordinary skill that the thermal treatment materials depicted in
The material for the carrier substrate, such as 106, 112, 122, and 142, can be selected so that the optical properties of the carrier substrate may vary with temperature. This feature can be used as a temperature indicator when using ultrasound, fluoroscopy, MRI and other imaging techniques. Also, the material for the carrier substrate may be selected so that the viscosity of the carrier substrate can be increased to the point of becoming a viscoelastic solid when a static external magnetic field is applied thereto. For instance, the static magnetic field may be applied to a target location so that the particles, such as 102, formed of metal and contained in the carrier substrate, can be disposed within the location.
The carrier substrates 106, 112, 122, and 142 may be in the form of a fluid with a viscosity of 0.3×10−3-50 PaS. The material for the carrier substrate may be selected such that the interaction between the carrier substrate and the particles suspended in the carrier substrate can hold the carrier substrate within the target location, too, i.e., the thermal treatment materials, such as 100, 110, 120, and 140, can have a property of a viscoelastic solid. By applying the magnetic field, the thermal treatment materials can be maintained at the target location for treatment.
The carrier substrates 106, 112, 122, and 142 may incorporate additional agent(s) to improve penetration into a fine cavity, where the additional agent can be an organic compound (e.g., surfactant) which will reduce the surface tension on the tissue. Alternatively, the carrier substrates may include additional agent(s) to improve adhesion to the tissue.
A venous system consists of a network of lumens and numerous venous valves that serve to prevent retrograde blood flow to the heart. These valves permit the flow of blood in one direction only (away from the heart). Varicose veins are the result of bicuspid valve(s) failure and/or dilatation of superficial veins in the venous system. Unlike existing treatment modalities, such as ligation of the damaged lumen (surgical, chemically, or with RF energy), surgical valve repair, grafting vein sections from other areas, and elevation of the legs and using elastic support hose, the thermal treatment materials 100, 110, 120, and 140 are use to treat various types of tissue, such as vein wall and venous valves, in a minimally invasive manner.
As depicted in
Upon inflating the balloon 210, an external alternating electromagnetic field is applied to the thermal treatment material in the balloon 210 so that the particles (such as 102, 116, 124, and 144) contained in the thermal treatment material convert the electromagnetic field energy into thermal energy. The generated thermal energy may be used to shrink the weakened wall portion 208 in order to restore the functionality of the vein. As the venous wall 208 shrinks due to the application of heat energy, the pressure on the balloon 210 will cause the balloon to slowly deflate to maintain a constant and optimal pressure.
The balloon 210 can conform to any structures within the venous system and therefore provide optimal thermal transfer to the target tissue, such as the weakened wall portion 208 and valve leaflets 206. Also, the thermal treatment material is capable of delivering precise thermal energy, minimizing the formation of undesired heat lesions, char, or blood coagulation. More detailed information of the balloon 210 and catheter 202 can be found in the previously referenced U.S. patent application Ser. No. 11/801,453.
Upon inflating the two sets of balloons, an external alternating electromagnetic field is applied to the thermal treatment material in the first set of balloons 302a, 302b so that the particles (such as 102, 116, 124, and 144) contained in the thermal treatment material convert the electromagnetic field energy into thermal energy. The second set of balloons 308a, 308b are inflated to temporarily block the blood flow, to thereby minimize conductive and convective heat loss during the treatment.
In
As depicted, the catheter 400 includes suction holes 402 formed in the wall thereof and a heat generator 404 formed along the wall thereof. The suction holes 402 are connected to the ductal lumen 401 in the catheter 400. The catheter 400 may be connected to a vacuum system (not shown in
The heat generator 404, formed of ferrimagnetic, ferromagnetic, or super-paramagnetic materials, converts external alternating electromagnetic energy into thermal energy. The heat generator 404 can be formulated so that it is thermally self regulating and able to control the energy delivered to the target portion 408. The dimension, shape, and pattern of the heat generator 404 may be determined based on the shape and extent of the target tissue, such as the target vein wall portion 408 and the valve leaflets 206 (
Conventional imaging technologies (ultrasound, fluoroscopy, etc.) may be used to position the catheter/heat generator into position within the vein 406. Both the catheter 400 and the heat generator 404 may be formed of materials to aid in imaging and navigation through the vein 406.
The human body contains numerous body cavities, many of which can be afflicted with diseases that may be effectively treated by applying sufficient thermal energy to destroy or inactivate the malignant cells in the target area. For example, the uterine cavity in a woman's body may develop abnormal uterine bleeding (menorrhagia), which is a common problem for menstruating women. The thermal treatment materials, such as 100, 110, 120, and 140, may be use to perform thermal treatment of the endometrial lining tissue inside the uterine cavity.
As depicted, the catheter 500 includes lumens 502, 503 and a balloon 504 formed on the outer surface of the catheter. One of the lumens 503 is in fluid communcation with the balloon 504 so that the fluid to inflate the balloon can be introduced via the lumen 503. When inflated, the balloon 504 seals the cervix 506, to therby prevent any leakage of fluid/thermal treatment material outside the uterine cavity 510. The other lumen 502 is used to inject (or evacuate) various types of material into (or from) the uterine cavity 510.
Next, in a step 536, an external alternating electromagnetic field is applied to the thermal treatment material filled in the uterine cavity 510. Then, the particles contained in the thermal treatment material convert the EM energy into thermal energy, where the generated thermal energy is used to ablate the endometrium tissue inside the uterus. An exemplary EM generator disclosed in U.S. patent application Ser. No. 11/823,379, can be used to provide the external EM field. The catheter 500 may be preferably formed of polymer(s) to prevent inadvertent heating.
In a step 538, it is determined whether the thermal treatment is completed. If the answer to the step 538 is NO, the process proceeds to the step 536. Otherwise, the process proceeds to a step 540. In the step 540, the physician removes the thermal treatment material from the uterine cavity 510 by aspiration via the lumen 502. Optionally, the uterine cavity 510 can be flushed with a saline solution in a step 542. Also, any particles remaining in the uterine cavity will be removed within a few days after the treatment via the vagina. Finally, the catheter 500 is removed from the uterus in a step 544.
In a step 558, it is determined whether the aspiration/injection cycle has been repeated a preset number of times. The aspiration/injection cycles correspond to “pressure swings” that ensure the full coverage of thermal treatment material inside the uterine cavity 510. The amount of thermal treatment material delivered into the uterus between successive pressure swings and the pressure inside the delivery system could be used as an indicator of the thermal treatment material coverage. If the answer to the step 558 is NO, the process proceeds to the step 554. Otherwise, the process proceeds to a step 560. In the step 560, the thermal treatment material is injected into the uterine cavity 510.
The process for treating the uterus in
The thermal treatment materials, such as 100, 110, 120, and 140, may be use to perform thermal treatment of the human breast. For instance, intraductal breast cancer (ductal carcinoma in situ—“DCIS”) for patients with atypical ductal hyperplasia (ADH) may be thermally treated by use of the thermal treatment materials. Also, the thermal treatment materials may be used to perform a prophylactic procedure for patients with a high risk of developing breast cancer.
As depicted in
Next, in a step 716, a determination is made as to whether or not there is any other milk duct to be treated. If the answer to the step 716 is YES, the process proceeds to a step 718. In the step 718, the thermal treatment material is also injected into the other duct. Then, the process proceeds to the step 716. If the answer to the step 716 is NO, the process proceeds to a step 722.
In the step 722, an external alternating electromagnetic field is applied to the thermal treatment material filled in the milk duct 704. Then, the particles contained in the thermal treatment material convert the EM energy into thermal energy, where the generated thermal energy is transmitted to the surrounding abnormal tissue and destroy it. An exemplary EM generator disclosed in the previously referenced U.S. patent application Ser. No. 11/823,379, can be used to provide the external EM field. The catheter 600 may be preferably formed of polymer(s) to prevent inadvertent heating.
In a step 724, it is determined whether or not the thermal treatment is completed. If the answer to the step 724 is NO, the process proceeds to the step 722. Otherwise, the process proceeds to a step 726. In the step 726, the physician opens the duct, i.e., the duct is injected with pressurized saline so that the duct would expand and allow the particles to be removed from the milk duct 704 by aspiration via the lumen 604. Optionally, the milk duct 704 can be flushed with a saline solution in a step 728. Finally, the catheter 600 is removed from the breast 702 in a step 730.
In a step 750, it is determined whether or not the aspiration/injection cycle has been repeated a preset number of times. The aspiration/injection cycles correspond to “pressure swings” that ensure the full coverage of thermal treatment material inside the milk duct 704. The amount of thermal treatment material delivered into the milk duct between successive pressure swings and the pressure inside the delivery system could be used as an indicator of the thermal treatment material coverage. If the answer to the step 750 is NO, the process proceeds to the step 746. Otherwise, the process proceeds to a step 752. In the step 752, the thermal treatment material is injected into the milk duct 704. Next, in a step 754, the lumen 604 is closed for the subsequent thermal treatment process.
It should be apparent to those of ordinary skill in the art that the size and number of suction holes formed in the catheter 600 may vary according to application. Alternatively, a ring shaped suction hole may be used in place of multiple suction holes. It is noted that the catheter 500 may be used in place of the catheter 600. In such a case, the balloon 504 is used to seal the gap between the catheter and the inner wall of the milk duct.
It is noted that multiple ducts can be treated simultaneously. As an example, a physician could fill two ducts using two different delivery systems, (or, equivalently two catheters), and apply the electromagnetic field around the breast simultaneously. If needed, the physician could select on the EM generator (EM generator is disclosed in the previously referenced U.S. patent application Ser. No. 11/823,379) the number of ducts to treat simultaneously. The EM generator may include information of various types of treatment cycles, each cycle including duration and EM field intensity, etc.
The pressure inside the catheter 500 (or 600) could be monitored to give a feedback to the injection system of the thermal treatment material, where the injection system is disclosed in the previously referenced U.S. patent application Ser. No. 11/823,380. For example, if a pressure outside the working pressure range is detected, the injector will set a warning signal or alarm. For another example, the injector can control the pressure by modulating a valve or pump to maintain an optimum working pressure. Also, if the pressure rises above or falls below a safe limit, the injection system may automatically abort the treatment procedure.
In a step 808, an external alternating electromagnetic field is applied to the thermal treatment material. Then, the particles contained in the thermal treatment material convert the EM energy into thermal energy, where the generated thermal energy is transmitted to the target neural tissue and destroy it. An exemplary EM generator disclosed in the previously referenced U.S. patent application Ser. No. 11/823,379, can be used to provide the external EM field. Then, in a step 810, it is determined whether the pain associated with the target neural tissue is reduced or eliminated. If the answer to the step 810 is NO, the process proceeds to the step 808. Otherwise, the process proceeds to a step 812. In the step 812, the treatment is completed.
Neural tissue can be also treated by use of a catheter/probe that includes a heat generator located at its tip. The heat generator is formed of ferrimagnetic, ferromagnetic, or super-paramagnetic material, and secured to the distal end of the catheter. When subject to an alternating EM field applied externally, the heat generator converts the EM energy into thermal energy. Detailed description of catheters having the heat generator can be found in the previously referenced U.S. patent application Ser. No. 11/801,453.
In the step 822, the target neural tissue is identified and located. Then, in a step 824, the heat generator located at the distal end of the catheter is placed into or in proximity to the target neural tissue. Subsequently, an external alternating EM field is applied to the heat generator for a specific period of time in a step 826. Next, in a step 828, it is determined whether the pain associated with the target neural tissue is reduced or eliminated. If the answer to the step 828 is NO, the process proceeds to the step 826. Otherwise, the process proceeds to a step 830. In the step 830, the catheter is removed from the treatment site. Then, the treatment is completed in a step 832.
In the thermal treatments discussed in conjunction with
The thermal treatment material, such as 100, 110, 120, and 140, can be used to treat fallopian tube occlusion. In another embodiment of the present invention, the thermal energy generated by the thermal treatment material can be used to denature the cellular structure of a portion of the patient's fallopian tubes, to thereby induce collapse and occlusion of the fallopian tubes. This technique prevents the eggs from ovaries from reaching the uterus, creating sterility in females. The technique consists of shrinking the fallopian tube using a category of materials that is capable of converting alternating magnetic field energy into thermal energy. The proteins within the fallopian tube are heated and denatured, resulting in shrinkage of the entire structure. In addition to the heat generating ferrite materials, physical barrier plug materials may be used as an adjunct to further promote the occlusion of the tube.
The aspect ratio of the plug 912 is determined such that it will always be oriented with its long axis parallel to the fallopian tube. As depicted in
It is noted that the external EM field applied to the ferrite materials and plugs in
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
This application claims the benefits of U.S. Provisional Application No. 60/992,771, entitled “Inductively heated materials with therapeutic properties” by Herbette et al., filed on Dec. 6, 2007, U.S. Provisional Application No. 60/992,764, entitled “A method of applying thermal energy into neural tissue” by Herbette et al., filed on Dec. 6, 2007, U.S. Provisional Application No. 60/992,756, entitled “Method for treating intraductal breast cancer by hyperthermia” by Herbette et al., filed on Dec. 6, 2007, U.S. Provisional Application No. 60/992,761, entitled “Method for treating human body cavity by hyperthermia” by Herbette et al., filed on Dec. 6, 2007, and U.S. Provisional Application No. 60/992,768, entitled “Method and apparatus for applying thermal energy to arterial and venous lumens and structures” by Herbette et al., filed on Dec. 6, 2007.
Number | Date | Country | |
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60992771 | Dec 2007 | US | |
60992764 | Dec 2007 | US | |
60992756 | Dec 2007 | US | |
60992761 | Dec 2007 | US | |
60992768 | Dec 2007 | US |