AU2001267808B2 - Foreign body retrieval device - Google Patents

Description

FOREIGN BODY RETRIEVAL DEVICE

Field of the invention

The present invention relates to a surgical apparatus for immobilization and evacuation foreign objects preferably from a human body. In particular the present invention refers to surgical extractors suitable for use in urological treatments like extracting calculi appearing in the biliary or urinary system.

It should be understood however that the present invention is not limited to the urological treatment of a human body. It can be successfully employed for surgical treatments of animals as well. Furthermore the present invention is not limited strictly to extracting calculi during the urological treatment. It is suitable for other surgical treatments, which might require retrieval of foreign objects from the body systems, e.g. from blood vessels etc.

Background of the invention Despite the fact that by virtue of available modern video-assisted endoscopic instrumentation significant progress has been achieved in urological less invasive treatment in general and in the extracting of foreign objects in particular, nevertheless the evacuation of such objects like calculi from the body remains a challenge for a surgeon. As an example of complicated and time-consuming surgical treatment one can mention removal of calculi of different size and characteristics from various sites along the urinary tract and from various locations within the body, e.g. removal of gallstones and kidney stones. This challenge results in development of a variety of surgical tools for stone retrieval without the need for major surgery. The calculi retrieval tools, or so-called surgical extractors usually comprise a flexible tubular catheter formed as a tubular sheath adapted to penetrate along the body passages to reach the location where the object to be evacuated resides. Within the catheter a wire or cable is located, which can be manipulated from the outside at the catheter's proximal end. The cable is connected with a basket-like element deployed within the sheet at the catheter's distal end. The basket like element consists of flexible wires made either of stainless steel or a memory shape material or any other material capable to provide the basket with elasticity. Depending on the manipulation the basket may either to retract inside the sheet to allow penetration of the catheter via passage or to protract from the catheter. In protracted position the wires open due to the elasticity of their material and form a cage thus to allow entering the object inside the basket through the open spaces left between its adjacent wires. Further retraction of the basket inside the sheath results in collapsing the cage and imprisonment the object in the basket. Removal of the catheter will enable the whole to be removed from the body organ together with the object immobilized within the basket. An example of the above-described surgical extractor is disclosed in FR 1197808. It can be easily appreciated that the particular design of the basket-like element is crucial for the easy immobilization and reliable retaining the object during evacuation.

Therefore various attempts to devise such basket-like element are known in the art, for example in http://www.bsci.com. According to recent classification suggested by Boston Scientific Corporation the currently employed basket-like elements for stone retrieval can be broadly categorized into following groups:

1. Flatwire baskets

2. Helical baskets

3. Multi-wire baskets The reason for the above situation lies in the fact that there is still felt a strong need in a simple, inexpensive and convenient surgical tool suitable for reliable and efficient evacuation of foreign objects from the body irrespective of the size of the object and its location within the body.

An example of a flatwire basket is disclosed in US6183482. This basket comprises one or more legs to retrieve the calculi. At least one of the legs has an inner and outer surface, which is curved to render the basket atraumatic. The inner surface can be flat such that the leg has a D-shaped cross-sectional configuration. It is reported in the literature that flatwire baskets minimize lateral basket wires movement and this facilitates and improves stone capture. Furthermore flatwire baskets open reliably even in an undilated ureter. Flatwire baskets are available in a wide range of sizes and wire configurations. A method of manufacturing of such baskets is described in US 5792145.

Unfortunately the intrinsic disadvantage of flatwire baskets is their unsuitability for capturing and immobilization of relatively small calculi, since the amount of wires in such baskets is limited to very few and the size of open space between the adjacent wires remains too large.

In an attempt to solve this problem and to allow capturing and retaining of small calculi so-called helical baskets were devised. Examples surgical extractors equipped with helical baskets can be found in US3496330, US 6190394, US 4347846. It is stated in the literature, that helical baskets incorporate strong, flexible wire construction in a spiraled shape design. The streamlined, spiraled shape is well suited for efficient, effective stone capture. As the basket is drawn back over the entrapped calculi, the configuration of the wires "sweeps" the stone into the basket.

In US 5496330 is disclosed helical basket formed as a plurality of strands encased in a sheath and wrapped in a helical form. Displacement of a portion of the threads from the sheath causes their wide angularly disposition to form a basket for retrieving the object. The threads comprise a plurality of individual filaments that are closely spaced through the length of the basket. By virtue of strands, formed as multiple, closely situated adjacent wires the number of contact points with entrapped calculi is increased without requiring a concomitant increase in the size of the overlying sheath or in the difficulty placing the basket over the calculi.

Nevertheless, one can assume that the above-mentioned advantage associated with the increased number of contact points may limit this basket to treatment of small calculi and render this basket less suitable for immobilization of relatively large calculi. The reason for this is close angular disposition of the filaments that prevents easy entering of large calculi in the limited open space between the adjacent filaments.

In US 6190394 is disclosed medical retrieval basket formed as plurality of flexible elements that are outwardly disposed to form a cage for entrapping objects therein. This basket was devised to enable efficient entrapment of the objects and their reliable holding within the cage. To achieve this goal the basket is manipulated by rotation and employs flexible elements having different sizes, different cross- sectional configuration and/or different spacing. In one embodiment the cage consists of non-twisted flexible elements as in flatwire basket design. In the other embodiment the flexible elements are helically twisted. In both embodiments the cage is symmetrical with respect to a plane drawn perpendicularly to the middle of the cage length. It can be assumed however that the above-mentioned intrinsic disadvantages associated with flatwire and helical baskets would be characteristic also to the basket disclosed in this patent. The further disadvantage of the helical design is associated with the fact that parallel-directed helically shaped filaments are prone to entanglement.

In US 4347846 is described surgical extractor employing a cage or basket formed by steel wires and disposed in a helical path. Some of the wires follow a helix in clockwise direction, while other wires, in equal number follow a helix in anticlockwise direction. By virtue of this extractor the reliability of retention of the body during evacuation is improved, since the body may enter within the extractor sheath when the cage is being retracted. This prevents accidental escape of the body from the cage. Furthermore, by virtue of opposite direction of helically shaped filaments any danger of their twisting and entanglement of the cage is avoided. It should be emphasized that the general shape of the cage employed in this extractor is very similar to the shape of helical basket disclosed in US 6190394. This shape is also symmetrical to a plane, drawn perpendicularly to the middle of the basket's length. Therefore the same above-mentioned intrinsic disadvantages are characteristic to this helical basket as well. Furthermore, since the filaments are not secured together and only have points of passive contact in which they overlap one can assume that the cage will neither have sufficient radial rigidity to prevent escape of the calculi between adjacent filaments, nor sufficient dilatation ability to provide enough room between the entrapped calculi and the tissue of the passage. Thus either loss of calculi during evacuation or damage of the adjacent tissue might occur during the treatment.

In an attempt to overcome the disadvantages associated with entrapment and retention calculi of various sizes a multi-wire parachute basket design was devised. Two sections define this basket. In the first section the amount of filaments is small and they are in spaced relationship to enable easy passage of the calculi through the spaces between the filaments. The second section is formed as plurality of filaments, extending from the filaments of the first section and defining a multi-wire cage. Since in this cage the filaments are in close relationship it is possible to ensure more complete engagement of the captured calculi when the basket in protracted position and its more reliable holding when the basket is being retracted within the sheath. One early attempt to devise a basket in accordance with the parachute concept is described in US 3472230. In this patent is disclosed a retrieval basket made of four spring wires connected to a slide. An umbrella made of suitable flexible web material is connected to the distal ends of the wires so that upon deployment of the basket the edges of the umbrella form a scraper. Retracting the basket is associated with scraping the debris from a body passage and its retaining within the umbrella.

The other example of retrieval parachute basket, provided with web umbrella is presented in US 4790812.

The disadvantage of parachute baskets provided with web umbrella is associated with difficulty in manufacturing and with relatively large size, which the web umbrella requires in the compacted condition.

The further progress in parachute baskets was achieved by devising multi-wire parachute baskets. The early attempt to design such baskets is described for example in SU 1036325. The more recent examples are disclosed in SU 202528 and US 6168603.

Surgical extractor described in SU 1036325 is provided with multi-wire parachute basket formed with a first section, which is proximal to the sheath and with a second section, which is distal thereto. The proximal section comprises two separate branches extending from the sheath in a V-shaped fashion. The branches comprise strings that are woven from the individual wire filaments. From distal ends of the branches emerge individual wire filaments, which are bent as elongated elliptical loops. The loops emerging from the branches meet in a common point at the distal end of the extractor. Longitudinally extending within the loops additional wire filaments are provided. These filaments divide the loops into supplemental branches, which together define the second section of the basket. The disadvantage of this basket is associated with the fact it still does not always ensures reliable retention of the calculi, since amount of branches along the basket is invariant and their filaments are parallel and separate. Thus small calculi might escape through the room between the branches of the second section. On the other hand, the elongated elliptically configured separate branches do not prevent possible damage to the nearby tissue caused by the large calculi that might protrude outside.

Substantially similar construction of multi-wire parachute basket is disclosed in US6168603. In this US patent is described surgical extractor at which distal end is arranged a plurality of wires defining a retrieval basket. Each wire comprises a first portion having an individual strand and a second portion comprising a plurality of filaments. When a retaining sheath of the extractor is retracted the wires formed of a shape memory material expand. Each strand assumes a spaced relationship to define a first section of the basket. Plurality of filaments defines a second section of the basket. Widely spaced wires of the first section promote capturing the object and closely spaced wires of the second section enable retention of the captured object. It is worth to mention that in one of the embodiments the second section is formed from filaments, which are helically wound and angularly spaced.

In SU 202258 is disclosed surgical extractor provided with a basket formed from at least two branches made of metallic strings. The main branches define the first section of the basket, which is intended for entering the calculus within the basket.

Each branch forms at its distal end sub branches, which are made of two main sub branch and one auxiliary sub branch. The sub branches define the second section of the basket. The sub branches and the auxiliary branches have different thickness and different elasticity. By virtue of this basket the reliability of entrapment and immobilization of the entrapped calculus is improved, since its construction allows variation of the amount and arrangement of the sub branches.

Unfortunately the above mentioned multi-wire parachute baskets only partially solve the problem of reliable capturing, immobilization and holding of a calculi irrespective of their size. The reason for this is the size of the open space along the branches, which is equal to the length of filaments of the second section. Calculi, which size is shorter than this length can easily escape from the basket. Furthermore, in the above baskets the filaments of neighboring branches are either fully separate (as in SU 1036325) or only passively overlap (as in US 6168603, SU 2022528) and they are not entwined. By virtue of this provision the radial rigidity of the cage is very limited and might be not sufficient to prevent possibility that the adjacent filaments will be spread apart by the calculus during its entrapment and thus the calculus can escape. Insufficient radial rigidity is associated also with the possibility for damaging adjacent body tissues by the entrapped calculus protruding through open space formed by the spread filaments.

The insufficient radial rigidity deteriorates dilatation ability of the whole basket and therefore contributes to the possibility for damage to the nearby body tissues.

In conclusion it should be emphasized that despite the fact that numerous surgical extractors employing retrieval baskets for evacuation of calculi or other objects from the body have been devised there is still a need for a new and improved device that will ensure efficient, reliable, easy and safe surgical treatment of foreign objects. Object of the invention

The main object of the present invention is to provide a new and improved surgical tool enabling sufficiently reduce or overcome the above-mentioned drawbacks of the known in the art tools.

In particular the first object of the invention is to provide a new and improved surgical tool, ensuring reliable immobilization and removal of an object from the body lumen irrespective of the object's size and configuration.

Still further object of the invention is to provide a new and improved surgical tool, which is provided with retrieval basket defined by increased structural rigidity and dilatation ability and thus reducing probability for traumatizing of adjacent body tissues.

Another object of the invention is to provide improved surgical tool, defined by easy and fast protracting and retracting from the sheath and thus enabling more reliable functioning during the surgical treatment.

Yet another object of the invention is to provide new and inexpensive surgical tool, ensuring adaptation to elastic properties of the surrounding body tissues. The above and other objects and advantages of the present invention can be achieved in accordance with the following combination of its essential features, referring to different embodiments thereof as a surgical apparatus and as a retrieval basket.

According to the embodiment of the invention, which refers to an apparatus it comprises a retrieval basket and a basket control means. The basket is suitable for immobilization the object and retaining thereof during evacuation and is defined by a first section, suitable for capturing the object and by a second section, suitable for retention the captured object. The first section comprises at least two branches, wherein distal ends of at least some of said branches are provided with loops emerging from the distal ends, said loops are configured from individual wire filaments to collectively define the second section of the basket. The basket control means is suitable for bringing the basket to the object and is adapted for manipulating the basket. The basket control means comprises a tubular sheath member to be inserted within the body. The basket control means is suitable either for retracting the basket within the sheath to enable bringing the sheath within the body or for protracting the basket from the sheath to enable opening of the basket.

In accordance with the embodiment of the invention, referring to a basket it is defined by a first section, suitable for capturing the object and by a second section, suitable for retention the captured object. The first section comprises at least two branches, wherein distal ends of at least some of said branches are provided with loops emerging from the distal ends, said loops are configured from individual wire filaments to collectively define the second section of the basket, wherein distal ends of at least some of the loops of the second section are in overlapping relationship to form dense meshed structure imparting structural rigidity and dilatation ability to the second section of the basket when it is opened.

The present invention in its various embodiments has only been summarized briefly. For better understanding of the present invention as well of its advantages, reference will now be made to the following description of its embodiments with reference to the accompanying drawings. Brief description of the drawings

Fig.l shows general view of the apparatus of the invention

Figs.2a-2d depict various views of the basket provided with two branches

Figs. 3a-3d depict various views of the basket provided with three branches Figs.4a-4d are various views of the basket provided with three branches, each of which is configured with two loops

Figs.5a-5d are various views of the basket provided with four branches, each of which is equipped with one loop

Figs.6a-6d are various views of the basket shown in Figs. 5a-5d in which the loops are configured in an 8 -like fashion

Figs. 7a-7f show schematically how distal ends of the loops are intertwined

Detailed description of specific embodiments

Referring now to Fig.l it is shown general view of a surgical apparatus 100, which is devised for retrieval of various calculi or other objects from human's or animal's body during urological treatment of biliary or urinary systems. This treatment may include evacuation of stones from urethra, evacuation of gall stones, kidney stones etc. The apparatus of the invention can be used also in other surgical treatments in combination with other surgical instruments and equipment, e.g. for destruction of calculi, etc. The apparatus of the invention comprises a retrieval basket portion 1 12 and a control means portion 114. The retrieval basket portion is suitable both for immobilization the object to be evacuated and for retaining thereof during the evacuation. The control means portion is suitable for manipulating the retrieval portion. For the sake of brevity the retrieval basket portion will be referred to further as retrieval basket and the control means portion as control means. Construction of the surgical apparatus of the present invention is similar to already mentioned surgical extractors. It includes flexible tubular catheter and a retrieval basket. The catheter is configured as a sheath 116 adapted to penetrate along the body passages near the location of the object. The basket is connected to a pushing rod 1 18 or cable or wire, which is arranged within the catheter and is connected to a manipulator 120. A surgeon by virtue of manipulator can manipulate the pushing rod and thus the basket either can be retracted within the catheter or protracted therefrom. The surgeon by holding the manipulator can also to maneuver the catheter within the body organ, e.g. to displace it by turning, pushing or pulling. In practice the surgeon brings catheter behind the object to be evacuated and then protracts the basket from the catheter. Once the basket is protracted it opens due to resiliency and is ready for receiving the object to be entrapped thereinto. The surgeon pulls catheter together with the basket until the basket is put on the object and thus evacuating the entrapped object from the body organ can be initiated. The retrieval basket comprises a first section 122, which is proximal the control means and a second section 124, which is distal thereto. The first section is made of strands 126 arranged in branches, which meet in a meeting point 128, where the retrieval basket is connected to the pushing rod of the control means. The strands consist of wire filaments, which are entwined and spatially arranged in such manners that upon protracting from the sheath they readily spread out. The filaments may have diameter 0.1-0.4 mm. The branches define the first section of the basket. In the open condition the first section of the basket has large open spaces, 130,132 left between the adjacent branches. It can be easily appreciated that by virtue of open spaces the immobilization of the object and receiving thereof inside the fist section becomes easy and convenient during the first stage of the treatment when the surgeon starts pulling catheter with the basket put on the object. As seen in Fig.1 the strands are arranged in three branches and define the first section of the basket. In practice it might be sufficient if only two branches define the first section.

From the distal ends of the branches emerge loops 134, which are configured from individual wire filaments. The loops are configured from the same wire filaments from which the branches are entwined. It is possible however that the loops are made of separate wire filaments and connected to the respective branches, e.g. by soldering. The most distal ends of the loops are secured together by a tip 136. Behind the tip the wire filaments are intertwined to form a straight short section 138 of the basket. This section functions as a guide to facilitate displacement of the basket within the sheath and to facilitate penetration and movement of whole device within the body organs. .

In accordance with the invention the adjacent to the tip parts of loops are spatially arranged in such a manner that at least some of them overlap. The overlapping wire filaments intersect each other and define collectively the second section of the basket. Furthermore, in accordance with the invention distal ends of at least some of the loops also intertwine one with another. By virtue of this arrangement the second section of the basket is configured as a spatial net, having cell structure, consisting of relatively small cells 140, suitable to retain therein reliably entrapped objects. Naturally, the size of the cells 140 is decreased towards the distal end.

It has been empirically revealed that this cell structure has improved radial rigidity dilatation ability thus rendering the whole basket less traumatic. The retention ability of the basket depends on the size and shape of the cells, which in turn could be controlled by the size of loops, their amount and spatial arrangement of their distal ends. These features of the invention will be described below with reference to further drawings. Furthermore, although it is not shown specifically in the drawings it should be understood that in accordance with the invention the amount of loops emerging from the branches could be similar or dissimilar and so their size. The branches and loops are configured from wire filaments made of metallic or non- metallic material having sufficient elasticity to enable opening the basket when it is protracted from the sheath. This material should be also biologically inert. In practice the wire filaments could be made of metallic material, e.g. stainless steel or organic material, e.g. Capron. It is also recommendable to coat metallic wire filaments by an inert coating, e.g. Teflon.

Now with reference to Figs.2a-c it will be described in more details the configuration of retrieval basket in accordance with an embodiment of the invention. In this embodiment, which in general is similar to the embodiment shown in Fig.l only two branches 202,204 define the first section of the basket 200 and thus relatively large open space is available between the branches enabling easy immobilization of large calculi. Branch 202 is provided with a couple of loops 206,208 and branch 204 is provided with respective couple of loops 210,212 having dissimilar size. It is seen that loop 206 is less than loop 208 and loop 210 is less than loop 212. Distal ends of the loops overlap and intersect in several points. For the sake of simplicity only two points, namely 214 and 216 are designated in Fig.2b to show intersection of the wires, from which loops 210 and 206 are configured. It can be seen that by virtue of this spatial arrangement net-like structure is formed, consisting of small cells, two of which, are designated in Fig.2b by numerals 218,220. It should be appreciated that by virtue of loops having dissimilar size it is possible to form additional cells without introducing new branches.

It is not shown specifically by should be understood that wire filaments, from which the loops are made can also intertwine one with another thus submitting additional structural rigidity to the net-like structure. It can be appreciated that by virtue of this configuration very reliable retention of the entrapped calculi or object is ensured when it is evacuated from the body organ.

Thus, in this embodiment the retrieval basket consists of a first section, defined by branches 202,204, and of a second section, defined by loops 206 208,210,212 and small cells. In practice it is advantageous if the length of the first section is about 2/3 of the total basket length and the length of the second section is about 1/3 of the total length. This is schematically shown in Fig.2a, the numeral L designates the total length. Still further embodiment of the invention is presented in Figs.3a-3d. Here three similar branches 310,312,314 define first section of basket 300. Each branch is provided with a dedicated loop 316,318, 320, emerging from the distal end of the corresponding branch. Distal ends of the loops spatially overlap and intersect. As best seen in Fig.3d, loops 316 and 318 intersect in points 322 and 324, loops 320 and 316 intersect in points 326,328 and loops 320,318 intersect in points 330,332. By virtue of this provision net-like structure is formed, consisting of small cells, some of which are designated in Fig.3d by numerals 334,336,338,340. The loops and cells collectively define second section of basket 300, in which the entrapped object can be reliably retained during evacuation. Similarly to the previous embodiment at least some of the individual wire filaments, from which the loops are made can also intertwine one with another and thus a net-like structure is formed, having improved structural rigidity.

Referring now to Figs. 4a-4c another embodiment of the retrieval basket will be explained. In this embodiment retrieval basket 400 consists of three branches 402,404,406. Each branch is made of four entwined wire filaments. At the distal end of each branch the filaments are arranged to form two loops, one of which has regular shape, while the second one is twisted and has an 8-shape configuration. It is seen, for example, in Figs.4a and 4b that wires 408, 410, 412, 414 emerge from branch 406. Two wire filaments 408 and 410 form regular loop, while two other wire filaments 412 and 414 are twisted and form an 8-shaped loop. Distal ends of the loops are in overlapping relationship and their wire filaments intersect. Some of the wire filaments are also intertwined. It is seen, for example in Fig.4a, that wire filament 410 of the loop referring to branch 406 intersects with wire filaments 416,418 of two loops emerging from branch 402. At the same time wire filament 416 of the loop referring to branch 402 intertwines with wire filaments 410 and 412 of the loop emerging from branch 406. It can be readily appreciated that by virtue of this arrangement the whole second section of the basket becomes a net, having dense meshed structure since twisted loops also contribute to formation of cells. The cells formed by intersection of the distal ends and the cells formed due to twisting collectively define the net-shape structure, which is especially suitable for reliable retention of small objects or calculi. At the same time sufficient space is still reserved between the branches to allow easy entrapment of relatively large objects or calculi.

Now with reference to Figs.5a-5d another embodiment of the invention will be explained. As best seen in Fig.5a basket 500 has its first section, defined by four branches 510,512,514,516. Each branch is provided at the distal end thereof with a loop, having elongated shape. One such loop emerging from branch 512 is designated in Fig.5b by numeral 517. Distal ends of the loops are in overlapping relationship and their wire filaments intersect with formation of plurality of small cells. Some of the cells are designated by numerals 518,520,522,524, 526,528. The cells together with loops define spatially the second section of the basket. It is not seen in the drawings, but should be understood that similarly to the previous embodiment at least some of the filaments, from which the loops are formed, can also intertwine, thus rendering the resulting structure additional structural rigidity.

Referring to Figs.6a-6e it is shown still further embodiment of the invention. In accordance with the embodiment four branches 610,612,614,616, which are provided at the distal ends thereof with corresponding loops 618,620,622,624, form basket 600. In contrast to the previous embodiments the loops are provided with dissimilar shape. The loops are bent in such a manner that additional small loops are formed at the distal end of each loop. In Fig.6e is shown one such loop 618, emerging from branch 610 and terminating by additional small loop 626. The additional loops are provided with circular shape and they intersect and intertwine thus defining dense net-like structure of the second section of the basket.

It can be readily appreciated that by providing the loops with various shape it is possible to vary also the size and shape of the cells, formed at intersection of the loops and thus so to control the retention ability of the basket. In practice the size of cells is 2-10 mm and they allow efficient entrapment of calculi with the size of more than 2 mm. Referring now to Figs.7a-7f it will be explained how individual wire filaments, from which the loops are made, could intersect and/or intertwine. By intersecting here is meant such arrangement of the filaments, in which one element passes through the perpendicularly directed filament and they overlap, i.e. one of the filaments is always over or under the other filament. By intertwining here is meant the situation when at least one filament twines with the perpendicularly directed filaments, i.e. it goes first above and then under them.

In Figs.7a-7f is shown schematically and with exaggeration different patterns corresponding to possible arrangement of individual filaments defining the cells. For the sake of simplicity the wire filaments are depicted as vertical and horizontal bands intersecting at right angle and defining orthogonal pattern, consisting of four vertical and four horizontal bands. It should be understood however that in reality thin wire filaments form the cells. The filaments are directed with respect to each other not necessarily at right angle and their amount is not limited to four by four pattern. In Fig.7a is shown a pattern in which all wire filaments intertwine one with another, i.e. each horizontal wire filament intertwines with all vertical filaments and vice versa. It is seen, for example, that vertical filament 710 goes first under horizontal filament 712, then above horizontal filament 714, then again under horizontal filament 716 and finally again above horizontal filament 718. On the other hand horizontal filament 712 goes first above vertical filament 710, then under vertical filament 720, then again above vertical filament 722 and then again under vertical filament 724. The rest of filaments are arranged similarly.

In Fig.7b is depicted another situation, in which the filaments both intertwine and overlap with intersection. It is seen that vertical filament 726 intertwines with horizontal filaments 728,730,734 and intersects with the perpendicularly directed filament 732.

In Fig.7c is shown still new pattern, consisting of intertwined and intersecting filaments. It is seen for example that two neighboring vertical filaments 736,738 go under two neighboring horizontal filaments 740,742 and then above two next horizontal filaments 744,746.

In Figs.7d-7f are shown further possible patterns, consisting of intertwining and intersecting filaments. In the last pattern, seen in Fig.7f each filament intersects with three perpendicular filaments and intertwines with only one filament.

It can be realized that the patterns depicted in Figs.7a and 7f present two extreme situations, corresponding respectively to the pattern in which all filaments intertwine and to the pattern in which only one filament intertwines, while the other filaments intersect. Having explained various cells patterns, in which the filaments of the loops might be arranged still another embodiment of the apparatus of the invention will be disclosed. In this embodiment opening of the basket is ensured not by elasticity of the wires material as in the previous embodiments, but by virtue of thermo mechanical shape memory characteristic of the material from which the wires are made. The suitable alloy may be super elastic alloy based on Ni and Ti, like Nitinol or any other suitable commercially available alloy having shape memory ability, i.e. the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. In this embodiment the basket control means comprises power supply source for passing electric current through the wires and capable to cause them to change their shape due to heating. Insulating coating, which can be made of Teflon, coats the wires. The advantage of Teflon is its thermal resistance and low coefficient of mechanical friction, which leads to additional reduction of traumatism. Furthermore, manufacturing of the basket wires from Nitinol renders the whole basket ability to undergo reversible deformation up to 10%, which is close to thedilatation ability of living tissues. It can be readily appreciated that basket made of Nitinol becomes compatible both biologically and mechanically with the adjacent tissues, since it is capable better to copy the topography of the organ in which the basket resides. By virtue of improved compatibility the basket becomes less traumatic. Still further advantage oft using Nitinol is associated with the "superelastic" properties of this material and the capability of this alloy to improve its "rigidity" when the temperature increases. Introducing of a catheter with deployed therein Nitinol basket into a body organ, having temperature higher then the ambient temperature increases elasticity of the basket and its dilatation ability, which improves the ability of the basket to reliably entrap and retain the object or calculi to be retrieved. It should be also mentioned, that due to the "superelastic" properties of Nitinol surgical extractors employing baskets made of it have longer service life, then extractors with baskets made of stainless steel. It can be appreciated that by virtue of the above-described construction of the retrieval basket, provided with overlapping loops, the whole surgical apparatus of the present invention becomes very simple, inexpensive, easy and reliable in operation. The surgical tool of the invention is capable to conveniently immobilize and reliably retain both small and large objects and at the same time it is less traumatic due to basket's improved structural rigidity and dilatation ability.

It should be understood that the present invention should not be limited to the above described example and embodiments. One ordinarily skilled in the art can make changes and modifications without deviation from the scope of the invention.

It should be appreciated that the features disclosed in the foregoing description, and/or in the following claims, and/or in the accompanying drawings may, both separately and in any combination thereof, be material for realizing the present invention in diverse forms thereof.

Claims (28)

Claims:

1. A surgical apparatus for evacuation of foreign objects from a body organ or passage, for example for retrieval of stones from urethra, gall stones or other calculi, said apparatus comprising: a retrieval basket suitable for immobilization the object and retaining thereof during evacuation, said basket is defined by a first section, suitable for capturing the object and by a second section, suitable for retention the captured object, the said first section comprises at least two branches, wherein distal ends of at least some of the branches are provided with loops emerging therefrom, said loops spatially define the second section of the basket; wherein distal ends of the loops are in overlapping relationship and at least some of them are intersecting with formation of cells, which define collectively a net-like structure capable to retain the captured object within the second section of the basket. a basket control means suitable for bringing the basket to the object and manipulating the basket during retrieval, said basket control means comprising a tubular sheath member insertable within the body organ, said control means is suitable either for retracting the basket within the sheath or for protracting the basket from the sheath to enable its opening.

2. The apparatus as defined in claim 1, in which at least some of the distal ends of the loops are intertwined.

3. The apparatus as defined in claim 1, in which at least some of the loops are twisted and configured in a 8-like fashion.

4. The apparatus as defined in claim 1, in which said loops are of dissimilar size.

5. The apparatus as defined in claim 1, in which said loops are made from wire filaments.

6. The apparatus as defined in claim 5, in which said wire filaments are made of metallic material.

7. The apparatus as defined in claim 6, in which said material has shape memory characteristic.

8. The apparatus as defined in claim 7, in which said material is Nitinol.

9. The apparatus as defined in claim 6, in which said metallic material is stainless steel.

10. The apparatus as defined in claim 5, in which said filaments are maid of organic material.

1 1. The apparatus as defined in claim 10, in which said material is Capron.

12. The apparatus as defined in claim 5, in which a coating coats the filaments and said coating is Teflon.

13. The apparatus as defined in claim 1, in which said basket control means comprises a handle means, which is operatively connected to a pushing means, said pushing means extends along the sheath and is bound to the meeting point of the branches with possibility to retract the basket into the sheath or protract it therefrom upon manipulating the handle means.

14. The apparatus as defined in claim 13, in which said pushing means comprises rigid rod, or wire, or stranded wire elements.

15. The apparatus as defined in claim 1, in which said basket control means comprises a controllable electrical power source connected to the basket.

16. A retrieval basket for evacuation of foreign objects from a body organ or passage, for example for retrieval of stones from urethra, gall stones or other calculi, said basket is defined by a first section, suitable for capturing the object and by a second section, suitable for retention the captured object, the said first section comprises at least two branches, wherein distal ends of at least some of the branches are provided with loops emerging therefrom, said loops spatially define the second section of the basket, wherein distal ends of the loops are in overlapping relationship and at least some of them intersect with formation of cells, which define collectively net-like structure capable to retain the captured object within the second section of the basket.

17. The basket as defined in claim 16, in which at least some of the distal ends are intertwined one with another to form dense meshed structure imparting structural rigidity and dilatation ability to the second section of the basket when it is opened.

18. The basket as defined in claim 16, in which at least some of said loops are configured in a 8-like fashion.

19. The basket as defined in claim 16, in which said loops are made from individual wire filaments.

20. The basket as defined in claim 19, in which said wire filaments are made of metallic material.

21. The basket as defined in claim 20, in which said material has shape memory and superelastic characteristic.

22. The basket as defined in claim 21, in which said material is Ni-Ti based alloy.

23. The basket as defined in claim 22, in which said material is Nitinol.

24. The basket as defined in claim 20, in which said metallic material is stainless steel.

25. The basket as defined in claim 19, in which said filaments are made of organic material.

26. The basket as defined in claim 25, in which said organic material is Capron.

27. The basket as defined in claim 19, in which a coating coats the said wire filaments.

28. The apparatus as defined in claim 27, in which said coating is Teflon