WO2005070309A1

WO2005070309A1 - Pliable loop made of nitinol for perendoscopy treatment of pedunculate polyps

Info

Publication number: WO2005070309A1
Application number: PCT/IT2005/000037
Authority: WO
Inventors: Mario Immacolato Paternuosto
Original assignee: Mario Immacolato Paternuosto
Priority date: 2004-01-26
Filing date: 2005-01-25
Publication date: 2005-08-04
Also published as: EP1708628A1; ITRM20040033A1

Abstract

A shape-memory device for the treatment of pedunculate polyps by endoscopy, wherein the periphery of the strangulating portion having a varied geometrical shape is partly elastic and extensible and partly rigid and inextensible. In particular, according to the invention, such inextensible, rigid portion is a filament of Nitinol covered by an insulating sheath, and the elastic portion consists of a filament of latex or other elastic material connecting two suitable points of the Nitinol filament to each other. The filament of Nitinol brought to the programmed temperature will bend so as to take a shape similar to the Greek letter alpha in its small letter form, i.e. an open circle and two arms put on each other at a cross point. Upon rotation of the Nitinol filament on itself the loop is tightened around the polyp’s peduncle. The strangulation will then be uniform all over the circumference of the peduncle. The loop may be made of any size.

Description

Pliable loop made of Nitinol for perendoscopy treatment of pedunculate polyps

The present invention relates to peptic endoscopy and, more specifically, an aid for strangulating pedunculate polyps to be used in particular endoscopic techniques such as polipectomy of peduculate polyps by a metal loop to prevent its bleeding. As known, such technique consists in that the open metal loop is passed around the polyp's head. In this position the metal loop is tightened round the peduncle and is supplied with an electric current. The final result is the resection of the polyp's peduncle.

STATE OF ART

The polyp's peduncle has arterial, venous, lymphatic vessels and nerve endings. The greater the polyp's peduncle, the larger the vessels and nerves mentioned above. Upon cutting the peduncle by an electric current with the prevailing effect of tissue coagulation or a current with the mixed effect of cutting and coagulation, the vessels are subjected to occlusion due to the necrosis induced by the current and the spasm of the vessels' walls. To do that, the current should be kept at a suitable intensity for enough time. If the current is not able to occlude the arterial vessels, a real danger is haemorrhage. Haemorrhage is prevailingly of arterial type and, if remarkable, could make an endoscopic operation unfeasible in a very short time. The unsuitable sight of the endoscopic field prevents the operator even from seeing the bleeding stump of the peduncle. Under such circumstances, only a surgeon can face up to this problem if an emergency endoscopy is useless or unfeasible.

It should be appreciated, however, that an operation can risk the patient's life if the latter is old. In fact the risks of an operation are remarkable especially in eldest patients who have unfortunately the largest polyps with the greatest peduncles. The operations of an emergency endoscopy are the same as those for the prevention of a haemorrhage caused by polypectomy, i.e. injection of adrenaline, endoloop and endoclips. The emergency endoscopy could be dramatic and has to be absolutely prevented. Blood and clots are a big problem and make such techniques extremely difficult, if not impossible, as the amount of blood accumulated in the lumen of the intestine increases with time under haemorrhagic conditions, and the function of the endoscope's pipe is compromised by the clots that clog it upon suction.

Another technique used upon bleeding caused by polypectomy is to catch the bleeding stump again by the same loop as used for the polypectomy and to grip it for five minutes. This technique needs, however, great dexterity and decision-making by the operator who must carry it out as soon as possible before he cannot see the stump any longer because of blood. In case of a considerable haemorrhage, the aids are not easy to be used and request a great operating ability.

TECHNIQUES IN USE FOR PREVENTING BLEEDING DUE TO POLYPECTOMY Injection of adrenaline:

The injection of a ten thousandth adrenaline acts both as a vasospas and a mechanical compression due to the wheal formed by the injection. However, it has a number of restrictions: a) Haemorrhage is not avoided at all at the next resection of the peduncle; b) Its effect is limited in time; c) The injection into the peduncle cannot be easily made especially if the peduncle is small but large enough to cause a haemorrhage after being cut. Use of endoloops:

Endoloops give a number of problems so that endoscopy operators prefer not to use them: a) Endoloops cannot always be tied round the head of a polyp especially if the latter forms an intestinal obstruction and has a villous surface. Even if it is stated correctly that a polyp with a large head has also a large peduncle, generally this is not the case. In practice, it is much more difficult to position endoloops around polyps just where endoloops could more help to avoid the danger of a bleeding. b) Endoloops can easily be positioned to a wrong position because of their light texture, i.e. too ear the head of the polyp so that they can slip off upon cutting the peduncle. c) Endoloops can be wrongly positioned to the head of the polyp so that the next polypectomy is very difficult. d) The long tail which the peduncle is provided with is a further undesired cause that makes the resection of the peduncle difficult. e) When endoloop is tied round the peduncle, it is not ensured that it is tightening round the desired tract of the peduncle. f) The step when endoloop is tied round the peduncle has a blind time in which undesired portions of the intestinal wall could also be tightened. g) The tightening of the endoloops is a no-return step so that the endoloops can hardly be released from the polyp by the operator after it has even partially been tied round the peduncle. h) It is sometimes impossible to eject an endoloop from the tube or to release an endoloop from its support so that the operator has to cut the peduncle at risk of bleeding by an usual endoscopic resection.

Considering what _. above disclosed as well as the fact that haemorrhages occurring upon cutting the peduncles are not a lot because they generally occur subsequently after polypectomy, it has been suggested to position endoloops to the cut peduncle stump. However, this is not always possible as the stump withdraws after resection. Use of endoclips: The use of an endoclip allows the polyp's peduncle to be attacked and compressed without any loop that has to step over the polyp's head like endoloop. The endoclip is positioned directly at the polyp's peduncle before the latter is cut. After the peduncle is cut, the endoclip remains at the stump of the peduncle. However, its use is restricted as it (being metallic) is electroconductive as well as difficult to be positioned and then needs a considerable ability by the operator, and sometimes more than one endoclip are necessary to achieve the desired result which is to clamp the peduncle and its vessels as well.

The transmission of the current to the intestinal wall can lead to the perforation. The contact between loop for polypectomy and endoclip is not unusual especially if the polyp has a short peduncle and more than one endoclip are positioned obliquely so that the contact can occur at the back of the peduncle when the metal loop is tightened for the polypectomy.

Another drawback of the endoclips consists in that the polyps with large and long peduncles rest often on the intestinal wall and then the mucous membrane of the intestine can easily be caught as the endoclips seize the peduncle. Loops made of Nitinol: In order to overcome all of the drawbacks and the problems of the several above-mentioned techniques of strangulating a pedunculate polyp by endoscopy, Italian Patents No. 1,305,290 and No. 1,317,934 of the same Applicant suggested the use of a filament provided with thermal memory and having the shape of a loop like the Greek small letter "alpha" which is sheathed under rest conditions by a rigid, straight sheath that keeps it in a stretched, elongated shape. The filament takes the "alpha" shape again as it is released from the straight sheath at the predetermined temperature.

As well known, some alloys such as an alloy of nickel and titanium which is designated by the trade name Nitinol have a thermal memory, i.e. they are able to take a programmed shape as they are exposed to a predetermined temperature.

As a result, according to the Patents mentioned above, if a filament of Nitinol is programmed to take the shape of a Greek small letter alpha at the temperature of the human colon and, before use, i.e. when the filament is outside the body, it is kept at a straight shape at low temperature, it is possible to insert such straight filament into a tube with suitable diameter so that it passes easily through the channel of a colonoscope or similar endoscopic apparatus. Its use is easy. The endoscope is positioned in front of the polyp's peduncle to be cut. The tube containing one or more loops of Nitinol in its distal length is pushed outside the channel. As it is desired to position the loop around the peduncle, a suitable pusher contained in the tube pushes to the outside the set of loops of Nitinol. The pusher is a catheter which easily passes through the tube and by which cold water can be injected into the tube of the endoscope to^' avoid the increase in the temperature (which is advantageous at the very beginning) when the endoscope is in the intestine. Such increase would cause the loops of Nitinol inside the tube of the endoscope to bend, which is undesired as the friction would increase and less loops could be charged into the final length of the tube. Cold water has to be kept inside the tube and not injected into the intestine so that the temperature of the latter is not lowered. To do that, a spurt of water is splashed to a tract of the intestine non to be treated. Water will remain in the pushing catheter which is sealed by the syringe.

Keeping the temperature low in the tube has further advantages: 1) a longer set of loops can be used; 2) the loops pushed outside the tube do not wind quickly. As the loop pushed by the operator comes out of the tube containing and forcing it to keep the straight shape and is subjected to the temperature of the intestine, it will take the alpha shape to which it was programmed. As it takes the loop shape, it will wind round the polyp's peduncle so as to strangulate it. As it comes out from the tube and begins to bend, the loop of Nitinol is guided by the operator by suitable torsions of the endoscope. The loop of Nitinol will turn round the peduncle so as to grip it like a vice, thus blocking the haematic flow in irreversible manner.

Peculiarities of the already known loops of Nitinol: In the solution disclosed in the above-mentioned Italian Patent No. 1,305,290, the strangulating function is performed by an air tube surrounding the loop of Nitinol which is inflated after the loop has surrounded the polyp's peduncle. A plug of latex allows the needle at the catheter's point to enter the air tube surrounding the loop and to inflate it at due time. The catheter with its needle also serves as pusher of the loop. However, such system proved to be too complex and not free from faults. The compression was quite occasional and not foreseeable as the air tube aimed always at slipping either upwards or downwards along the axis of the peduncle, thus making the pressure, that must instead be constant, on the polyp's peduncle useless. In addition, the air tube took too much room and could only be used for polyps with very long peduncles. There was also no limit to the bending speed of the filament of Nitinol. The suggested solution,, i.e. filling the sheath of latex surrounding the filament of Nitinol with cold water to slow down the bending speed, proved in practice to be unfeasible. In fact, the sheath filled in advance with air. Furthermore, the contact between needle and plug, in which the needle was fixed and from which the latex sheath surrounding the filament of Nitinol led off, easily loosened during such filling. Italian Patent No. 1,317,934 discloses a device in which the loop of Nitinol is used alone to perform the strangulating function, i.e. without air tube surrounding the loop of Nitinol which has to be inflated after the loop has surrounded the polyp' s peduncle. However, there is the problem that the filament of Nitinol provided with means for the electrical insulation from the intestinal walls forms a knuckle or eyelet with constant size upon winding to form an alpha-shaped loop. Therefore, there is no adaptability to the several size of the polyp's peduncles so that polyps with thin peduncles are strangulated insufficiently and those with larger peduncles are strangulated excessively. In practice, there is the need of a system for solving the problems mentioned above by providing a different solution able to allow the strangulating loop to be constantly adapted to the size of the polyp's peduncle.

The present invention seeks to provide a shape memory device for treating pedunculate polyps by endoscopy wherein the periphery of the strangulating portion having a varied geometrical shape is partly elastic and extensible and partly rigid and inextensible. In particular, according to the invention, such inextensible, rigid portion is a shape memory filament such as a filament of Nitinol covered by an insulating sheath, and the elastic portion consists of a filament of latex or other elastic material connecting two suitable points of the Nitinol filament to each other. The filament of Nitinol brought to the programmed temperature will bend so as to take a shape similar to the Greek letter alpha in its small letter form, i.e. an open circle and two arms put on each other at a cross point. Upon its bending the filament will seize the elastic loop around the polyp's peduncle to strangulate it. The description of the invention will be more readily understood with reference to the accompanying drawings that show only by way of a not limiting example some preferred embodiments thereof. In the drawings:

Fig. 1 shows a loop made of Nitinol in which the filament is fixed at two opposite points of its lower half;

Fig. 2 shows a filament made of Nitinol according to the invention at the beginning of the formation of the alpha-shaped loop;

Fig. 3 shows a second embodiment where the elastic filament forms a noose inside the loop made of Nitinol;

Fig. 4 shows the noose of Fig. 3 during the strangulating step of the pedunculate polyp;

Fig. 4a is a detail of Fig. 4;

Fig. 5 shows the loop of Fig. 1 during the strangulating step of the pedunculate polyp;

Fig. 6 shows schematically the device when it is being pushed by a pushing catheter outside the containing tube; Fig. 7 shows the case in which there are several loops inside the tube which are pushed simultaneously from the pushing catheter.

With reference to the figures, the filament of Nitinol indicated at 2 is inside an insulating sheath 5 which is a little longer than the filament so as to prevent the distal end of the latter which is opposite to the spherical swelling 1 from touching the intestinal walls.

As can be seen in Fig. 1, the elastic portion of the device formed by an elastic filament 3 is attached to the filament of Nitinol in two points 4 positioned at opposite sides with respect to vertical axis of symmetry Y of the loop formed by such filament as it is brought at the. programmed temperature preferably in the vicinity of the crossing point of the distal arms of the filament. Fig. 2 shows the filament that starts to bend from the straight form. The filament rotates then on itself by 180° and turns further round until its two arms cross. According to a feature of the invention, the elastic portion of the device can be attached to several points of the circumference or loop formed by the rotation of the filament of Nitinol 2 so that a strangulating portion is defined inside such loop with a periphery comprising at least a length of elastic, extensible material. In the preferred embodiment illustrated in Figs. 3, 4 and 4A, the strangulating portion consists of an open loop which is integral with the filament of Nitinol at the two opposite points 4 which meet at 9 where the two distal arms of the Nitinol filament cross after rotation.

It should be noted that the two arms of the Nitinol filament have different lengths so that the longer arm, that is double as long as the other, comes out first from the tube 10 containing it (Fig. 6) . The instructions for use are as follows:

The filament of Nitinol is programmed to turn at the temperature of 37°. An open circumference is thus formed from which the two distal arms of the Nitinol filament with different lengths are originated. The length of such circumference which is open at the cross point of the two arms of the loop will vary according to the size of the peduncle which has to be strangulated. As the device disclosed is pushed from the pushing catheter 12 into the intestinal lumen outside tube 10, the direction of rotation of the device after its output from the tube will be clearly determined by the direction of the distal end of the device which is not provided with the spherical swelling 1 which is instead present at the other end. It is evident that in this step it is possible for the operator to take accurate aim by a slight torsion of the endoscope. The thrust for the device to come out of tube 10 is provided either by a catheter including a polipectomy loop 7 or a pushing catheter 12 by which cold water can be injected to reduce the friction of the device which is prone to bend in the tube as it is exposed at the temperature of the intestine. In the embodiment in which the pushing catheter 12 is used, several devices, as can be seen in Fig. 7, can be positioned at the distal portion of tube 10 where cold water can be let in to reduce the friction incurred by the devices.

Just after the output of the Nitinol loop, followed soon after by the strangulation of peduncle 8, the loop of steel 7 can be pushed outside to perform the polypectomy.

The elastic loop is tightened round the peduncle 8 of polyp 6 by the rotation of the Nitinol filament on itself. The strangulation will be uniform all over the circumference of the peduncle. The loop can be made of any size within the area of the circle described by the rotation of the Nitinol filament on itself. In the embodiment shown in Figs. 1 and 5, the elastic filament 3 is not fixed to both distal ends of the Nitinol filament at point 9 where both filaments cross but at different points of the circumference formed by the rotation of the Nitinol filament. The farther the connection points 4 on the alpha-shaped circumference from the cross point 9 of the two distal ends of the Nitinol filament, the greater the polyp's peduncles that can be strangulated. In such second embodiment the strangulating modes are different as the portion for strangulating the polyp ^■ consists predominantly of a rigid component formed by the Nitinol filament and an elastic component formed by the elastic filament which is only a more or less long section of the strangulating portion.

According to the invention the strangulating method which is stronger for large peduncles will be carried out by elastic filaments that connect points of the circumference above the equatorial axis of the latter at the distal side with respect to the cross point of the Nitinol filament. As the connecting points of the elastic filament to the circumference approach the antipodes of the cross point of the distal ends of the Nitinol filament, the elastic character of the peduncle compression mechanism diminishes because the length of the elastic filament is reduced. For this reason, under the latter conditions, the strangulation mechanism will not be flexible but rigid and strong as it is carried out more or less predominantly by the anelastic Nitinol filament.

In this second embodiment the filament has an essentially horizontal arrangement so that the points of connection to the Nitinol filament are placed at the same distance from the cross point of the distal ends .

A further embodiment provides the non-equidistance of points 4 of connection to the elastic filament from cross point 9 of the Nitinol filament rotating on itself. It is thus provided a strangulating portion in which the cross point of the distal ends is not anymore the vertex of an hypothetic triangle the base of which is the more or less long elastic filament forming more or less a loop. The new strangulating portion has a semi-lunar shape in which the elastic filament in its extreme position will connect an end of the Nitinol filament to the point where it crosses the other distal end, and the other point on the circumference is the farthest position from the first point. This further embodiment has the advantage that the thrust of the peduncle towards the elastic filament during the rotation of the Nitinol filament will be carried out by a tract of the Nitinol filament without a break.

At last, according to a further embodiment, the device has no spherical swelling 1 at the end opposite to the distal end. In this case, the length of sheath 5 exceeds the length of the Nitinol filament also at the proximal end and can be tightened between the jaws of pliers for endoscopy. By this way, the device can not be pushed outside the tube 10 by a pushing catheter or a catheter provided with a loop- for polypectomy but by a catheter provided with biopsy pliers, with the advantage of slowing down the speed of release from the tube.

Claims

1. A device for strangulating the peduncles of intestinal polyps by endoscopy comprising a memory shape wire or filament which bends and wind round a peduncle at a programmed temperature so as to take a shape of a loop similar to the Greek letter alpha in its small letter form, characterized in that the strangulating portion is included inside said alpha letter and its periphery comprises at least a tract of elastic, extensible material.

2. The device according to claim 1, characterized in that the non-extensible, rigid portion of the strangulating tract consists of said shape memory filament.

3. The device according to claim 1, characterized in that said elastic tract consists of a filament of latex or other elastic material connecting two points of said shape memory filament to each other.

4. The device according to claim 1, characterized in that the portion to strangulate the peduncle is provided by an open circumference originated at a programmed temperature by the rotation on itself of a shape memory filament having two points of its length connected to each other by an elastic filament of latex or a synthetic material with similar characteristics .

5. The device according to the preceding claim, characterized in that the two points of the shape memory loop filament connected by the elastic filament are essentially equidistant from the cross point of the two distal arms of the shape memory filament.

6. The device according to claim 3, characterized in that the ends of said elastic filament connected to the shape memory filament are disposed at the cross point reached by the distal arms of the shape memory filament upon rotating on itself, thus providing that the strangulating portion is completely formed only by the elastic filament.

7. The device according to any preceding claim, characterized in that the temperature at which the rotation of the shape memory filament and the shape of the loop like the Greek small letter alpha is programmed is the temperature inside the lumen of the intestine.

8. The apparatus according to preceding claims 1 to 6, characterized in that the shape memory filament is metallic and programmable to turn at any temperature.

9. The device according to any preceding claim, characterized in that the shape memory filament is wrapped all over its length by an insulating sheath so that no electric charge can be transmitted to said filament upon cutting the peduncle.

10. The device according to claim 6, characterized in that one of the two arms of the loop in the shape of a letter alpha is provided at its end with a swelling that helps the thrust of the loop for polypectomy or the pushing catheter placed inside the tube behind the device .

11. The device according to claims 8 to 10, characterized in that the length of the insulating sheath covering the shape memory metal filament exceeds the length of the final tract of said filament not provided with the swelling so that the point of the metal filament is harmless towards the intestinal wall.

12. The device according to claim 11, characterized in that the length of the insulating sheath exceeds the length of the shape memory filament also at the proximal end so as to allow pliers for endoscope to catch ah end thereof, thus providing that a catheter provided with biopsy pliers can be used instead of a pushing catheter or a catheter provided with a loop for polypectomy, and that the speed of release from the tube can be slowed down.

13. The device according to any preceding claim, characterized in that both elastic filament and shape. memory filament are susceptible of having different shape, section, length and thickness.

14. The device according to -any preceding claim, characterized in that the shape memory metal filament is a filament made of Nitinol.