|Typ av kungörelse||Ansökan|
|Publiceringsdatum||24 dec 2008|
|Registreringsdatum||18 jun 2007|
|Prioritetsdatum||18 jun 2007|
|Publikationsnummer||PCT/2007/50293, PCT/NL/2007/050293, PCT/NL/2007/50293, PCT/NL/7/050293, PCT/NL/7/50293, PCT/NL2007/050293, PCT/NL2007/50293, PCT/NL2007050293, PCT/NL200750293, PCT/NL7/050293, PCT/NL7/50293, PCT/NL7050293, PCT/NL750293, WO 2008/156353 A1, WO 2008156353 A1, WO 2008156353A1, WO-A1-2008156353, WO2008/156353A1, WO2008156353 A1, WO2008156353A1|
|Uppfinnare||Cornelis Hendrikus Anna Wittens|
|Sökande||Wittens Cornelis Hendrikus Ann|
|Exportera citat||BiBTeX, EndNote, RefMan|
|Citat från patent (3), Hänvisningar finns i följande patent (2), Klassificeringar (6), Juridiska händelser (4)|
|Externa länkar: Patentscope, Espacenet|
CRYO PROBE , METHOD FOR SHAPING A CRYO PROBE
The invention relates to a cryo probe, configured to be entered in a body for minimal invasive cryosurgery, having at least one internal channel for connection to a cryogenic fluid supply such that cryogenic fluid can be supplied to an end portion of the probe, wherein the end portion of the probe has an elongated cooling tip, comprising thermally conductive material for freezing tissue.
The invention also relates to a method for shaping a cryo probe that is configured to be entered in a body, which probe has an elongated tip for freezing tissue to the tip, wherein the tip has a diameter of approximately 3 mm or smaller, preferably approximately 1.6 mm or smaller.
Furthermore, the invention relates to a method for performing cryosurgery.
Venous ulcers account for a large morbidity and high treatment costs, mainly because of the slow healing and high recurrence rate. Several methods are used to treat chronic venous insufficiencies in patients. At present, treatment of the superficial venous system in combination with dissection of Incompetent Perforating Veins (ICPV) is perceived to be a relatively successful method for treating for patients with chronic venous leg ulceration. For treatment of venous ulcers in areas above the ankle, which can be caused by venous hypertension, it is preferred to apply dissection of ICPV in combination with dissection of the superficial venous system. The objective of ICPV is to decrease venous reflux and reduce ambulatory venous hypertension. Dissection of ICPV can for example be treated by Subfascial Endoscopic Perforating vein Surgery (SEPS), open perforantectomy (Linton procedure) and ultrasound-guided sclerotherapy.
For many surgeons SEPS is currently the surgical technique of choice in treating ICPV. This technique is mainly suitable for the treatment of ICPV on the medial aspect of the lower leg. In this technique, a deflated balloon is inserted through a cut in the calf. Thereafter the balloon is inflated such that a space is created and the surgeon can access the perforating veins that are causing the problem. The perforating vein is then sealed or clipped so that blood cannot go through the vein at all, stopping the reflux. Due to compartmental tapering at the ankle, the narrow confines have proven challenging for SEPS.
Recently, a new way of dissecting ICPV, Cryo Perforator Surgery (CPS), has been developed. Some of the promising advantages of CPS are that it is less invasive than SEPS and provides access to substantially all of the ICPV regardless of their location, resulting in a more extensive therapeutic range. Also, CPS doesn't necessarily require intraluminal insertion of the cryoprobe in the ICPV, e.g. contrary to sclerotherapy. Moreover, the CPS procedure can be performed under local anaesthesia and is less invasive, as opposed to SEPS for example.
In a study on the feasibility of CPS, prior to the treatment, the incompetent perforating veins were identified using duplex ultrasound (ATL 5000) and ink-marked on the skin. Using local anaesthesia, the perforating veins were approached percutaneously, placing a 14 GA Venflon canule at the fascia defect under ultrasound guidance. The Venflon canule could be placed intra or extraluminal near the ICPV. A cryoprobe of a type commercialised by Erbe®, 1.6 mm in diameter and with a smooth tip, was entered through the canule and frozen for 15 seconds at -89° Celsius. The perforating vein was freeze-attached to the cryoprobe and dissection was obtained by withdrawing the probe vigorously.
The treatment was considered successful when the incompetent perforator showed no signs of flow despite augmentation on the duplex scan. Follow-up duplex scans were performed two and four weeks after treatment, respectively. The total follow up for all patients was four weeks. The follow-up duplex scans showed successful treatment for 39% of the treated ICPV. For the present invention, a goal is to improve the rate of successful treatments for CPS (Cryo Perforator Surgery), at least on ICPV (Incompetent Perforating Veins), while maintaining most of the current advantages of CPS. This goal and/or other goals can be achieved by a minimal invasive cryosurgery instrument, comprising a cryo probe that is configured to be entered in a body, the probe having at least one internal channel for connection to a cryogenic fluid supply such that cryogenic fluid can be supplied to the probe, wherein an end portion of the probe has an elongated cooling tip, comprising thermally conductive material, for freezing tissue to the tip, which tip has a roughened surface for attachment of frozen tissue to the tip.
Tests have shown that by roughening the tip of a cryo probe the grip of the tip on the surrounding ice is substantially improved as compared to a conventional probe tip. With a cryo probe having a better grip the ICPV can be dissected in a more controlled and secure manner. Although conventionally a cryo tip is constructed with a smooth tip, it appeared that also a roughened tip can be entered percutaneously into tissue without disadvantageous friction or damage to tissue . For example, in one application the roughened tip is entered through a perforating vein, of which at least a part is ICPV, until it reaches the intended ICPV part. After introduction, and when the probe tip is brought to a cryogenic temperature, the ICPV is frozen and attached to the tip and when the probe is pulled back the concerning ICPV is dissected. During entry the vein may be somewhat damaged by the roughened tip, however since the vein is dissected when pulling back the probe, damage that might have occurred will not affect the patient. In another exemplary application, the tip is entered through tissue that is less sensitive to the roughened surface of the tip. For example, the tip may be entered through subcutaneous fat, to which no harmful damage will be caused by the roughened tip.
In another application, the tip or at least a part of it, is initially covered by a cover and the tip is at least partially uncovered and brought into contact with the ICPV before said tip is brought to said temperature. An example of a suitable cover is a tubular sheath or a cap. In use, the tip is entered with the cover until it reaches the desired location, after which the cover is removed, e.g. pulled back or destructed, or the tip is pushed through the cover, and the tissue concerned is frozen to tip. Thereafter the cryo probe is pulled back and the tissue dissected.
In again another application, a catheter is used to guide the cryo probe through the body. In use, the catheter is entered in the body of a patient and the cryo probe is guided through the catheter. When the catheter has reached a location close to the tissue that needs to be dissected, the tip is uncovered by moving the tip and catheter relative to each other, e.g. for a couple of mm's or em's, such that the cryo tip is exposed and tissue can be frozen to the tip. Then the tissue is frozen and pulled back together with the cryo probe and/or the catheter. As will be clear for the skilled person, the use of a cover or catheter, e.g. as an aid for the roughened cryo tip and/or protection for the tissue, may be advantageous or redundant, depending on the application.
With the roughened tip according to the invention, the contact surface between frozen ICPV tissue and the roughened tip is increased such that the frozen tissue remains better attached when the probe is pulled back. An improved grip of the tip on the surrounding frozen substance is obtained, such that the rate of successful treatment can be improved.
In a preferred embodiment, the roughened surface comprises diamond particles, i.e. a diamond dust, that are attached to the tip. While conventionally such a diamond particle coating is used in the art for its cutting or abrasive qualities on human tissue, here it principally leaves surrounding tissue unharmed, i.e. when being guided through the body, while exhibiting advantageous attachment qualities when it is under a cryogenic temperature. Moreover, the application of diamond particles attached to the tip is advantageous because they may remain relatively unaffected when the probe is applied at cryogenic temperatures for multiple times.
Furthermore, abovementioned goal and/or other goals can be achieved by a method for shaping a cryo probe that is configured to be entered in a body, which probe has an elongated tip for freezing tissue to the tip, wherein the tip has a diameter of approximately 3 mm or smaller, preferably approximately 1.6 mm or smaller, wherein the tip is roughened by creating recesses and/or projections in the tip.
Abovementioned goals can also be achieved by a method for performing cryosurgery, wherein a cryo probe is used, having an elongated cooling tip with a roughened surface for attachment of frozen tissue to the tip, wherein the probe is entered in a body and the tip is brought in proximity to a target tissue, wherein the tip is brought to a temperature under approximately -75°C such that said target tissue is frozen and attached to said tip and wherein the probe is withdrawn to dissect said target tissue.
In clarification of the invention, these and further embodiments of the invention, and advantages thereof will be further elucidated with reference to the drawing. In the drawing: figure 1 shows a schematic illustration of a minimal invasive cryosurgery instrument; figure 2 shows a cryo probe; and figure 3 shows a cryo probe accompanied by an enlarged view of the tip of the probe.
In this description, identical or corresponding parts have identical or corresponding reference numerals. The exemplary embodiments shown should not be construed to be limitative in any manner and serve merely as illustration.
In this description, it should be understood that the words "cryo", "cryogenic", or the like refer to low temperatures, for example approximately - 75° C or below, approximately -85°C or even approximately — 180°C or lower temperatures. "Cryo", "cryogenic", or the like should be understood as referring to temperatures that are used for freezing and attaching surrounding tissue, and should not be used in a limitative manner, as the skilled person will understand. While in other fields certain low temperatures may be referred to, e.g. below -150°C, these or any other convention known in that field concerning the use of the words "cryo", "cryogenic", or the like should not be construed as being limiting to the invention.
A schematic illustration of an example of a minimal invasive cryosurgery instrument 1 is shown in figure 1. The instrument 1 has a cryo probe 2 comprising the end of the instrument 1 that is to be brought into the body of a patient. The cryo probe 2 has a tip 3 that is made of thermally conductive material to be able to locally freeze the environment. A shaft 4 is constructed to conduct cryogenic fluid, for example liquid nitrogen, from a cryogenic fluid vessel 5 to the tip 3, wherein the cryogenic fluid circulates from the vessel 5 to the tip 3 and back, e.g. via channels 8, 9 of a cooling circuit. For example, the cooling circuit at least comprises a fluid inlet 8 and a fluid outlet
9, wherein the inlet 8 conducts a liquid nitrogen to the tip 3, where it evaporates and is conducted back to the vessel 5 through the outlet 9. Around the channels 8, 9 the shaft 4 comprises thermally insulating material up to the tip 3.
Another cryo probe 2 is illustrated in figure 2. In this example, the shaft 4 and the tip 3 have a diameter d of approximately 1.6 mm. Other diameters of suitable cryo probes 2, suited for use in the field of minimal invasive surgery, are for example 2 mm, 2,4 mm, or 3 mm. For example, the tip 3 may be made of a metal, for example titanium and/or surgical steel. In this example, the tip 3 has an elongate, cylindrical shape with a rounded end
10. The rounded end 10 may allow convenient passage through and/or along body tissue without unnecessarily damaging tissue. The shaft 4 is preferably flexible to be able to extend through a bended canal within a patient's body and has a length such that the probe 2 may reach almost any desired location within the body.
Further illustrative examples of cryosurgery instruments 1 and techniques that may be used according to the invention are for example disclosed in GB 1 482 424 and WO 2006/034295.
In general, when performing cryosurgery, the probe 2 is entered in a body and the tip 3 is brought in proximity to a target tissue, wherein the tip is brought to a temperature under approximately -75°C, e.g. -89°C, such that said target tissue is frozen and attached to said tip and wherein the probe is withdrawn to dissect said target tissue.
A preferred use for cryo probes 2 according to the invention is cryo perforator surgery (CPS) which may concern dissection of incompetent perforating veins (ICPV). A scenario for use of a cryo probe 2 according to the invention may be the same as known from CPS, or CPS studies. When an ICPV is located, the tip 3 is guided to the ICPV, such that the tip 3 of the probe 2 touches, or nearly touches, the ICPV. When the tip 3 touches, or is at least close enough to the ICPV concerned, the tip 3 is brought to the desired temperature, e.g. -89°C, such that the incompetent perforating vein freezes. The probe 2 is then pulled back such that the vein is torn off and the vein will no longer cause undesirable venous reflux.
Although CPS has promising advantages as opposed to other methods for ICPV surgery, the rate of success of conventional CPS is still not optimal because the perforating vein is not always dissected.
It has been found that when pulling back a cryo probe of a known type, the ice that has been formed around the tip 3 is sometimes left behind. The probe is pulled out of the ice, because the pulling force that the probe of the known type exerts is not enough to pull the ice out of its surroundings. This may be explained in the fact that the probe 2 and the tip 3 thereof are relatively smooth, to slide through the human body 2 relatively conveniently, which is necessary to prevent damaging tissue along the way into or out of the body.
In an embodiment of the invention, the surface of the tip 3 is roughened, which provides for better attachment of the tissue to the tip 3. Advantageously, in use, the tip 3 will not unnecessarily damage tissue while being entered into the body. For roughening the surface, diamond particles 6, i.e. diamond dust, may be attached to the tip 3, providing for a diamond coating 7 on the tip 3. Figure 3 shows an enlargement of a tip 3 with a diamond coating 7 comprising diamond particles 6. In an embodiment, the diamond particles 6 have an average diameter of about 20 micron, but of course this may vary substantially and higher or lower average diameters may also be advantageously applied. For example different diameters varying from 5 micron to 50 micron, or even 100 micron, could be applied. The diamond particles 6 may be secured to and/or embedded in the tip 3 by any suitable method. A diamond coating 7 may be particularly suitable for use of the invention because it will not degrade when used multiple times at cryogenic temperatures. Also, it is relatively biocompatible and durable material. With these advantages, the small particle size allows the tip 3 to be entered into tissue without damaging it, while maintaining a relatively strong adhesion properties to ice, i.e. under cryogenic temperatures.
As an aid in guiding the roughened tip 3, a catheter may be used. In use, before guiding the probe 2 through the body, the catheter is entered in the body, e.g. up to a location near to the tissue that is intended to be dissected. Then, the tip 3 is guided to the tissue and the catheter is pulled back such that the tip 3 is exposed, after which said tissue can be frozen and pulled back by the probe 2.
As another aid in guiding the roughened tip 3, a cover can be used that covers the tip 3, or at least a part of it. The cover can be retracted or destructed when the tip 3 has reached the tissue that is aimed for dissection. Then, the tissue can be frozen to the tip 3 and the whole is pulled back. Preferably, after use, tissue that might be attached is removed and the roughened tip 3 is sterilised such that it can be re-used. Diamond dust, i.e. diamond particles 6, has been proven to be suitable for re-sterilisation.
Instead of or next to diamond particles 6, other particles and/or coatings can be applied to the tip 3. For example, suitable particles may include carbon and/or silicium, as these materials may also allow micron sized recesses and projections to be created on the tip 3. Other materials that are suitable may be recognised by the skilled person. Furthermore, recesses and/or projections can be shaped in the tip 3, by shaping and/or treating the surface, e.g. without adding particles. In this case, also a roughened surface with good attachment properties can be obtained. For example, scratches, cuts, or the like, may be applied to the surface of the tip 3. The projections and/or recesses that are formed may have heights and/or depths, respectively, approximately equal to one of said diameters of said diamond particles 6 mentioned above. Likewise, the relatively small size of the recesses and/or projections of the roughened surface of the tip 3 may provide for a strong grip on the ice while showing advantageously minimal friction or damage to surrounding tissue.
In an embodiment, recesses are created in the tip 3, for example by removing material from the tip 3. In this case, care should be taken that the tip 3 maintains protected against leakage of nitrogen fluid. In an advantageous embodiment, a coating is applied on the tip 3 and/or projections are shaped in or on the tip 3, such that a certain solidness and/or thickness of the material of the tip 3 is upheld, e.g. to prevent that cryogenic fluid leaks from the probe 2. Diamond particles 6, or other suitable particles and/or coatings, can for example be attached to the tip 3 with the aid of chemical vapour deposition (CVD) and/or a plasma assisted surface treatment method, e.g. plasma CVD, although the particles 6 may for example also be mechanically embedded or adhesively secured. CVD and/or plasma assisted surface treatment methods are able to apply a micron sized thin coating in a relatively controlled way, while the surface of, in this case, the tip 3 remains relatively unaffected. Furthermore, by use of such methods the diamond coating 7 is suited to remain secured to the tip 3 surface under cryogenic temperatures and for multiple uses. Other advantages of such methods are known in the art. A study was made for testing the grip a cryo probe 2 according to the invention. The tested embodiment had a roughened tip 3, in this case by means of a diamond coating 7 with diamond particles 6 having an average diameter of approximately 20 micron. It appeared that conventional cryo probes, without diamond coating 7, had insufficient grip on the ice. After the test, the results of the test with a conventional probe were compared with the results of the test of the probe 2 according to the invention.
Both probes were hung in a small chamber of distilled water. The water was frozen around the probe and after 5 seconds, a pulling force was exerted on the cryo probes, via a tension spring, by means of a linear electro motor, until the probes were pulled out of the ice. The pulling force was digitally measured in kilograms (kg), by means of a linear potentiometer ,and noted in a spreadsheet in Excel®, at the moment of pulling the probe out of the ice. The whole test was repeated 50 times for each probe and the results were processed by statistical computer software (SPSS 11.0®). Table 1 summarises some of these results.
The conventional cryo probe showed an average pulling force of 2.95 kg, a median of 2.90 kg, and had a 95% confidence interval between 2.65 and 3.25 kg. The diamond coated cryo probe 2 showed an average pulling force of 10.67 kg, a median of 10.95 kg, and had a 95% confidence interval between 9.87 and 11.48 kg.
The test showed that for the cryo probe 2 having a roughened surface the pulling force was much higher before the probe 2 would loose grip on the ice. In particular the pulling force needed to pull the cryo probe 2 with a roughened surface out of the ice was 3.6 times higher than the pulling force that was needed for a conventional cryo probe. Therefore, it is assumed that the cryo probe 2 according to the invention has a stronger grip on ice, i.e. frozen tissue, than the conventional probe. It shall be obvious that the invention is not limited in any way to the embodiments that are represented in the description and the drawings. Many variations and combinations are possible within the framework of the invention as outlined by the claims. Combinations of one or more aspects of the embodiments or combinations of different embodiments are possible within the framework of the invention. All comparable variations are understood to fall within the framework of the invention as outlined by the claims.
|WO1997041784A1 *||6 maj 1997||13 nov 1997||Lehrer, Aharon||A method and a system for performing cataract surgery|
|US6551309 *||14 sep 2000||22 apr 2003||Cryoflex, Inc.||Dual action cryoprobe and methods of using the same|
|US20040078033 *||11 aug 2003||22 apr 2004||Alexander Levin||Cryosurgical instrument and its accessory system|
|WO2016030707A1||26 aug 2014||3 mar 2016||Laboratoires Urgo||Device intended to be applied to the skin|
|DE102009018291A1 *||21 apr 2009||28 okt 2010||Erbe Elektromedizin Gmbh||Kryochirurgisches Instrument|
|Internationell klassificering||A61F9/00, A61B18/02|
|Kooperativ klassning||A61B18/02, A61B2018/0262, A61B2018/0212|
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