Surgery – Instruments – Heat application
Reexamination Certificate
1999-04-07
2001-10-23
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Heat application
C606S009000, C606S010000, C606S013000, C607S088000, C607S096000, C607S100000
Reexamination Certificate
active
06306130
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods and apparatus for inducing blood vessel necrosis of unwanted or diseased, e.g., dilated, blood vessels.
BACKGROUND OF THE INVENTION
A blood vessel can be any vascular structure, e.g., an artery, a vein, or a capillary. A dilated blood vessel is usually associated with any one or more of a variety of disease conditions, e.g., telangiectasias and varicose veins.
Telangiectasias are skin manifestations of primary cutaneous disorders and systemic diseases. For example, linear telangiectasias are seen on the faces of patients with actinically damaged skin and acne rosacea and are found on the legs of patients with venous hypertension and essential telangiectasia. Mat telangiectasias are lesions of broad macules and are commonly found on the face, oral mucosa, and hands of patients.
Cutaneous disorders associated with telangiectasias include acne rosacea, actinically damaged skin, venous hypertension, essential telangiectasia, ionizing radiation, and Poikiloderma vasculare atrophicans. Telangiectasias are also associated with systemic diseases such as carcinoid, ataxia-telangiectasia, mastocytosis, dermatomyositis, xeroderma pigmentosa, scleroderma, lupus erythematosus, hereditary hemorrhagic telangiectasia, and cirrhosis.
Varicose veins are dilated, tortuous superficial veins that result from defective structure and function of the valves of the veins, from intrinsic weakness of the vein wall, or rarely from arteriovenous fistulas. Varicose veins can be categorized as primary or secondary. Primary varicose veins originate in the superficial system while secondary varicose veins result from deep venous insufficiency and incompetent perforating veins, or from deep venous occlusions causing enlargement of superficial veins that serve as collateral veins.
Patients with varicose veins are often concerned about the cosmetic appearance of their legs, but varicose veins are also often associated with various physical symptoms as well. For example, symptoms can include a dull ache or pressure sensation in the legs after prolonged standing. In addition, extensive venous varicosities may cause skin ulcerations near the ankles. Superficial venous thrombosis may be a recurring problem and rarely a varicosity ruptures and bleeds, leading to more severe symptoms.
Treatments for dilated blood vessels, especially varicose veins, include sclerotherapy and surgical therapy. In sclerotherapy, a sclerosing solution such as hypertonic saline or surfactants is injected into the involved blood vessels, which results in deformation of the vascular structure. Surgical therapy involves extensive ligation and stripping of the greater and lesser saphenous veins. However, administration of these therapies usually requires high technical skill. Furthermore, the common patients, fear of needles and surgical procedures prevents many from seeking these treatments.
Laser and other light sources have also been used in photothermolysis therapy to treat dilated blood vessels, such as varicose veins. Selectively-absorbed light, e.g., in the form of pulses, is used to damage the vessels while sparing the surrounding tissues. However, reperfusion of treated blood vessels reduces the effectiveness of the treatment. Multiple treatments are often required because of reperfusion of a treated vessel. In addition, reperfusion of a treated vessel is undesirable because of clotting factors and thrombolytic factors associated with the process. Photothermolysis therapy is in common use for lack of a better alternative despite the relatively high cost, number of treatments, and risk of post-treatment pigmentation.
SUMMARY OF THE INVENTION
The invention is based on the discovery that by non-invasively heating the walls of a blood vessel to a temperature of at least about 60° C., and then forcibly pressing together or collapsing the walls for a time sufficient to allow them to cool, the vessel walls become adhered or “welded” together, resulting in closure of the vessel lumen, irreversible necrosis and degradation, and thus removal of the blood vessel during the subsequent healing. The new non-invasive methods greatly reduce reperfusion of a treated vessel, and substantially improve the efficacy of conventional photothermolysis therapy.
In general, the invention features a non-invasive method of inducing necrosis and degradation of a blood vessel, e.g., a dilated vein, in a tissue, such as skin, by non-invasively heating walls of the blood vessel to a temperature of at least about 60 (and up to about 100) degrees centigrade, and collapsing the blood vessel by applying pressure (e.g., 1 to 10 atmospheres) to the tissue surrounding the blood vessel for a period of time and with a force sufficient to collapse the blood vessel and to permanently weld the apposed walls of the blood vessel together, whereby the blood vessel undergoes necrosis.
The energy source can be an optical source, such as a pulsed or scanned optical source, e.g., a laser, or it can be a flash lamp, e.g., a xenon flash lamp. Ultrasound and radio frequency energy sources can also be used. For example, the optical source can be a visible or near-infrared optical source that emits in a wavelength range of 500 to 1100 nanometers and delivers optical energy with exposure durations of, e.g., 1 to 100 or 5 to 50 milliseconds.
The pressure has to be applied at the right time, e.g., after heating is completed, for example, when blood within the vessel is vaporized. For example, pressure can be applied within one thermal relaxation time of the blood vessel after the vessel walls are heated to at least 60 degrees centigrade. The pressure must also be maintained for an adequate time, e.g., at least one thermal relaxation time of the blood vessel. Pressure can be applied by mechanical compression, hydraulic compression, or pneumatic compression.
The new method can be used to remove unwanted blood vessels in a variety of disorders including varicose veins, acne rosacea, actinically damaged skin, venous hypertension, telangiectasia, Poikiloderma vasculare atrophicans, vascular malformations, hemangioma, ataxia-telangiectasia, lupus erythematosus, hereditary hemorrhagic telangiectasia, and cirrhosis.
In another aspect, the invention features an apparatus for inducing necrosis and degradation of a blood vessel in a tissue. The apparatus includes an external energy source that delivers energy, e.g., non-invasively, to the blood vessel that is preferentially absorbed by the blood vessel (for a time sufficient) to heat the blood vessel walls to a temperature of at least about 60 degrees centigrade, and a pressure source connected to the energy source to apply pressure, e.g., non-invasively, to the blood vessel once the blood vessel walls have been heated to at least about 60 degrees centigrade for a period of time and with a force sufficient to collapse the blood vessel and to permanently weld the apposed walls of the blood vessel together, whereby the blood vessel undergoes necrosis.
The energy source can be an optical source, e.g., a laser, such as an alexandrite, semiconductor diode, Nd:YAG, dye, copper vapor, argon ion, or krypton ion laser, or a flash lamp. The energy source can also be a radio frequency generator or an ultrasound generator. For example, the optical source can be a visible or near-infrared optical source that emits in a wavelength range of 500 to 1100 nanometers and delivers optical energy with exposure durations, e.g., pulses, of, for example, 1 to 100 or 5 to 50 milliseconds.
In different embodiments, the pressure source can be a hollow chamber filled with pressurized air that compresses skin when the chamber is placed in contact with the skin, or a solid or flexible surface or plate that presses against the tissue, thereby indirectly compressing the blood vessel. The pressure can be 1 to 10 atmospheres.
The apparatus can further include a cooling source, such as a sapphire block, which is in contact with a skin area exposed to the energy source during the heating of the blood vessel. For example, the coolin
Anderson Richard Rox
Dierickx Christine C.
Dvorak Linda C. M.
Fish & Richardson P.C.
Kearney R.
The General Hospital Corporation
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