WO2006038247A1

WO2006038247A1 - Pneumobasket for capturing and removing choledocus stones

Info

Publication number: WO2006038247A1
Application number: PCT/IT2005/000585
Authority: WO
Inventors: Mario Immacolato Paternuosto
Original assignee: Mario Immacolato Paternuosto
Priority date: 2004-10-08
Filing date: 2005-10-07
Publication date: 2006-04-13
Also published as: ITCE20040004A1

Abstract

The present invention relates to a particularly difficult endoscopic technique by which stones are extracted from the choledochus by means of a metal basket. The extraction of the stones from the choledochus by using the metal basket is not always successful because the basket fails in capturing the stone that cannot then be extracted. The present finding seeks to cause the basket filaments (5) running along the thickness of the walls of an air bladder (4) to be spaced apart from one another by blowing air into said inflatable air bladder which is located in the proximal basket’s length. The filaments of the distal basket’s length will be provided with a rotating potential energy after the air bladder is inflated, thus helping the capture of the stone by the basket.

Description

Pneumobasket for capturing and removing choledocus stones

The present invention relates to the operational endoscopy of the bile ducts and namely a device for capturing choledochus stones.

The presence of stones in the choledochus duct is a pathology that is solved by endoscopy in most cases. This is perhaps the most extraordinary operation of an endoscopic therapy. After having cut the papilla, the operator of the endoscope uses more frequently, even if not only, aids such as a balloon for the removal of stones and a Dormia's basket. None of both devices guarantees safe capture and removal of the choledochus stones.

The balloon can break easily as well as move the stone sideways during the removal and go beyond it, thus failing in its duty to move it to the wide ostium of the sphincterectomy.

In fact the balloon pushes the stones effectively only if the thrust is applied perpendicular to the tail of the stones. As the balloon is pulled, the feeding canaliculus will tend to take up a rectilinear shape, which will push the stone sideways and the thrust on the balloon will gradually lose its effectiveness. In other words, the inflated balloon will push the stone more and more sideways until going beyond it.

This situation is emphasized by that the surfaces of stone and balloon opposite to each other are both convex. The above-mentioned argumentations are based upon the assumption that the maximum diameter of the choledochus is not greater than the maximum diameter of the inflated balloon. If the choledochus is more or less widened, it is very difficult to apply a thrust to the tail of the stone if the latter has not a suitable size.

It may also occur that the stone of the choledochus can slip to the opening of the sphincterectomy because of the thrust of the inflated balLoon and hits a partially closed ostium due to a not sufficient sphincterectomy.

Under these undesired circumstances, the only solution is to deflate the balloon, to remove i_t, to push again the stone to the high portion of the choledochus and to try again by means of a Dormia' s basket. Dormia' s basket is the second solution followed by the endoscope operator to remove a stone away from the choledochus after having captured it and operated the necessary sphincterectomy. It is a device that is generally used after the balloon has failed. To capture a stone by the Dormia' s basket has the advantage that the stone can be broken and reduced to a size able to pass through the ostium of the sphincterectomy in case the stone i.s initially too large or the sphincterectomy is too naxrow. Dormia' s basket generally consists of four metal filaments coming out of the peripherry of the output hole of a metal canaliculus in opposite positions. Basket and canaliculus integral to each other are contained in a second channel and pushed to the outside of which, thus causing the basket filaments to open and to capture the stone which penetrates the space among the filaments. This is the aim, however, which is not achieved in most cases, i.e. the stone fails in entering the Dormia' s basket because of the following conditions:

- the stone is large and the basket filaments are compressed, deformed and displaced by the mass o±. the stone and do not succeed in wrapping the latter even if the basket is opened;

- sometimes the basket is not able to open and then ■ slips between the stone and the wall of the choledochus, and keeps its own filaments bundled together as if it is still in the canaliculus.

As a basket filament is compressed by the mass of the stone, the deformation gives the filament an elastic potential energy which should induce it to move to the opposite direction as a response to the release of such energy so that the filament turns around and capture the stone.

It is self-evident that this elastic potential energy induced by the deformation decreases as the distance from the connection points between basket filaments and the periphery of the output hole of the metal canaliculus increases. When the basket opens and tries to capture the stone, the length portion of the basket filaments subjected to the maximum deformation is the middle portion, i.e. the most expanded portion of the basket. The object of the present invention is to provide the basket with the maximum effectiveness for capturing the stone. The improvement of the performance of the basket is achieved according to a peculiar feature of the invention by blowing air under the control of the operator into a pyramidal air bladder which contains the metal filaments within the thickness of its own walls, the filaments rejoining to one another at the distal end of the basket opposite to the filament exit from the base of the pyramidal air bladder. FUNCTIONAL FEATURES OF THE INVENTION

As pyramidal air bladder is inflated, it causes the basket filaments to take up positions opposite to one another. This movement helps the stone to enter the basket. The entrance of the stone inside the basket is the restrictive measure for the good operation of the basket.

As the pyramidal air bladder is inflated, the basket filaments integral with the air bladder are spaced apart from one another even if one or more of them are compressed in the choledochus by the stone. Each metal basket filament is forced by the air blown into the pyramidal air bladder to move as a response to the deformation caused by the compression of the stone. This elastic potential energy is a force vector which is too weak in a conventional basket to induce the filament to jump over the stone under any condition. The peculiarity of the present finding is that it advantageously allows a strong rotating force vector to be applied to the metal basket filaments as they are forced to space apart from one another at the desired time of capturing the stone. The device of the present invention causes the function of the basket to change completely as its opening does not occur automatically and beyond control but can be controlled in a decisive, effective manner.

The pyramidal air bladder does not change the function of the basket in case it is not operated. It can be used whenever the normal function of the basket is not effective or can always be used from the first under a precise planning. Particular embodiments of the pyramidal air bladder allow it to be also used as balloon for the removal of stones.

Further features and advantages of the invention will result from the following detailed description with reference to the accompanying drawings in which:

Fig. 1 shows schematically a basket provided with an air bladder with pyramidal shape having the vertex centred on a hole of communication- with a feeding canaliculus which is coaxial to the cannula inserted into the endoscope before blowing air;

Fig. 2 shows the same basket of fig. .1 as the inflated air bladder has taken the shape of a overturned pyramid;

Fig. 3 shows a second embodiment in which the pyramidal air bladder has the base taking a concave or depressed shape at the end of the blowing;

Fig. 4 shows an air bladder with a pyramidal shape where rounded projections are present on the four walls;

Fig. 5 is a sectioned view of the variation of fig. 4.

With reference to the figures, according to a first embodiment shown in figs. 1 and 2, the device for capturing stones in the choledochus according to the present finding comprises an inflatable air bladder 4 consisting of PVC or another material having similar mechanical features and being able to take a pyramidal shape when it is inflated, and a canaliculus 2 preferably of plastic material through which air is blown into such air bladder. The vertex of the pyramidal air bladder 4 is joined to the canaliculus 2 at its output hole 3 from which metal filaments 5 come out one opposite the other.

Such filaments 5 extending from the base of the bladder rejoin to one another at a preferred spacing to form a basket. As can be seen in fig. 1, the basket with the pyramidal air bladder 4 and canaliculus 3 are contained within a cannula 1 which is inserted into the endoscope. As the endoscope operator pushes them outside cannula 1 into the choledochus, canaliculus 2 and air bladder 4 assume the positions shown in fig. 2. Filaments 5 are either blocked inside the thickness of the walls of pyramidal air bladder 4 as shown in fig. 5 or secured to inside and outside faces of the air bladder itself by known techniques. The base of the pyramidal air bladder is generally a square and the filaments come out of the base at its corners.

The base of the pyramidal air bladder is a generally even surface; however, in a preferred embodiment, the pyramidal air bladder can be made such that its base takes a concave or depressed shape at the end of the blowing of air, as seen in fig. 3. This is possible by causing in any way the centre of the base of the pyramidal air bladder to be connected with the vertex thereof. The depression of the base of the pyramidal air bladder allows it to fit easily the convexity of the captured stone.

A different arrangement of the pyramidal air bladder provides vaulted or rounded projections in the four walls that can .also be inflated as shown in fig. 4. The section of the pyramidal air bladder of such embodiment has the shape of a four-leaved clover (see fig. 5) . If suitably manufactured, these vaulted or rounded projections will mate to one another sideways when inflated such that they assume the structural shape and the function of a balloon.

In other words, by providing the pyramidal air bladder with such vaulted or rounded projections, the Dormia' s basket can also show the function of a balloon. It is self-evident from the foregoing that the present invention changes completely the operation of the Dormia' s basket of the prior art and establishes ideal conditions for capturing the stones because:

1) the filaments do not rest on only one fixed point any longer which is the anchoring point to the periphery of the ostium of the metal canaliculus in the conventional Dormia' s basket but advantageously their anchorage extends all over the length of the side walls of the pyramidal air bladder to which such metal filaments are connected.

2) according to the present invention, when the air bladder is swelling, the connection points of the basket filaments will not only expand but also approach the point of maximum expansion of the basket due to the mass of the stone, i.e. the central longitudinal length of the basket.

Another important feature of the present invention is that the blowing of air into the pyramidal air bladder will allow the metal basket filaments to be subjected to a thrust vector which is far greater than the elastic potential energy induced by the deformation of the filaments caused by the mass of the stone. The thrust vector induced by blowing air into the pyramidal air bladder has a circular direction as the stretching of the pyramidal air bladder causes the filament which is flattened by the mass of the stone to position in front or on one side of it. A basket having a pyramidal air bladder with rectangular base has particular functional prerogatives such as a much wider space between two filaments after the inflation of the bladder, thus allowing a deeper penetration of the stone.

WAY OF USE OF THE INVENTION

The reasons why conventional Dormia' s basket fails are as follows:

1) the basket expelled from the cannula contained in the choledochus does not open but slides along the gap between stone and wall of the choledochus, with the filaments being gathered together. 2) the basket opens but does not succeed in capturing the stone.

In the first condition, if the position of the stone in the choledochus is suitable, it is possible to resort to the device according to the invention by providing a pyramidal air bladder provided with vaulted or rounded projections so that it can be used like a balloon for the removal of stones. If ^'also this way fails in removing the stones or a device provided with the particular air bladder mentioned above is missing, the basket is either pushed or pulled such that the pyramidal air bladder is positioned under the stone and only at this moment air is blown inside the bladder. In case the basket opens but the stones cannot enter it, the pyramidal air bladder is inflated under the stone and a metal basket filament is caused to go beyond the stone by a forward and reverse motion.

Claims

1. A device for capturing and removing choledochus stones characterized in that it consists of a pyramidal air bladder (4) that can be inflated, with its vertex being centred on a hole (3) connecting it to a canaliculus (2) through which air is blown, and that metal filaments (5) coming out of said hole (3) run along the corners of the pyramidal air bladder (4) all over their length and extend beyond the base of the bladder and rejoin to one another at a suitable distance to form a basket.

2. The device for capturing and removing choledochus stones according to the preceding claim, characterized in that the base of said pyramidal air bladder (4) is rectangular or preferably square.

3. The device for capturing and removing choledochus stones according to claim 1, characterized in that metal filaments (5) are embodied in the wall of said pyramidal air bladder (4) .

4. The device for capturing and removing choledochus stones according to claim 1, characterized in that the angle spacing of the points on the periphery of said hole (3) from which metal filaments (5) forming the basket come out is constant.

5. The device for capturing and removing choledochus stones according to claim 1, characterized in that the base of pyramidal air bladder (4) can have any shape provided that metal filaments (5) come out of said base at points opposite to one another after having run along the corners of the pyramidal air bladder.

6. The device for capturing and removing choledochus stones according to claim 1, characterized in that canaliculus (2) for feeding air to the pyramidal air bladder (4) is coaxial to a cannula (1) with larger diameter containing the whole basket.

7. The device for capturing and removing choledochus stones according to claims 1, 2, 3, characterized in that filaments (5) forming the basket show a curved or a more or less arcuated shape in their length outside - the walls of pyramidal air^' bladder (4) according to the most preferred embodiments.

8. The device for capturing and removing choledochus stones according' to the preceding claims, characterized in that pyramidal air bladder (4) consists of PVC or a similar material with the same mechanical characteristics.

9. The device for capturing and removing choledochus stones according to any preceding claim, characterized in that pyramidal air bladder (4) has rounded projections (β) on its walls.

10. The device for capturing and removing choledochus stones according to claim 8, characterized in that the side walls of the rounded projections (6) come in touch to one another as pyramidal air bladder (4) is inflated such as to show a generally spherical shape.

11. The device for capturing and removing choledochus stones according to claim 4, characterized in that the base of pyramidal air bladder (4) is provided with a central depression to receive the apex of the stone.

12. The device for capturing and removing choledochus stones according to claim 2, characterized in that pyramidal air bladder (4) with square base is replaced by a conical geometrical figure which is inflated like said pyramidal air bladder (4) with square base.

13. The device for capturing and removing choledochus stones according to the preceding claim, characterized in that basket filaments (5) are made integral with the inside or outside face of the walls of pyramidal air bladder (4) by any technique.