WO2014188300A1

WO2014188300A1 - Introducer sheath device with expandable end

Info

Publication number: WO2014188300A1
Application number: PCT/IB2014/061374
Authority: WO
Inventors: Fabio Melchiorre
Original assignee: Fabio Melchiorre
Priority date: 2013-05-20
Filing date: 2014-05-12
Publication date: 2014-11-27
Also published as: ITMI20130816A1

Abstract

An introducer device (10) for percutaneous introduction into blood vessels and other ducts in the body comprises an outermost tube (11) having a distal end ( 12) intended to enter percutaneously and slide inside a duct, and a proximal end (15) provided with a valve element (14) with a leaktight axial passage (20). The outer tube removably houses a fascial dilator (13) inserted axially in the tube (11) through the passage of the valve element so as to project from the distal end (12) with its tapering end (16). The distal end (12) can be controllably moved between a rest condition and a radially expanded condition so as to form a funnel against the walls of the vessel. Advantageously an element with an expandable end (advantageously a "Fogarty" type balloon catheter) can slide inside the tube (11) and be used to remove material present in the duct (such as clots, foreign bodies, calculi, obstructing materials) by drawing them along the tube (11) and out of its proximal end.

Description

TITLE

" Introducer sheath device with expandable end " DESCRIPTION

The present invention relates to an introducer device, in particular for the percutaneous introduction of catheters into blood vessels and other ducts and for the removal of materials such as clots and other obstructing material.

Below, for the sake of simplicity, particular reference wil l be made below to blood vessels, for which the principles of this invention arc preferably used. It is however to be understood that these principles will also apply in the case of other duets present i n the human body.

Vascular catheters by means of which it is possible to pass through the blood vessels from an insertion point to a section of vessel on which it is desired to operate are wel ! known in the medical field. For example catheters used to remove embol isms (embolectomies) and similar obstructions in a blood vessel are known.

The access route to the vessel may be surgical ( in the overwhelming majority of cases this is the treatment of primary intent) or via mini -invasive percutaneous access without surgical incisions.

For example, at the present time, surgical embo!ectomy comprises a surgical incision in the vicinity of the area which must be treated (for example a lower l imb or upper l imb ). T he surgeon then proceeds to isolate the vessel requiring treatment by separati ng it I rom the overlying cuianeous and subcutaneous layers and then from the fascial and muscular 1 avers above and beneath the vessel. He then proceeds to make an incision in the vessel and introduces a small balloon catheter (Fogarty catheter ) into it. When the Fogarty catheter has passed beyond the embolism, the bal loon is inflated and drawn back towards the access point . In this way the fresh clot is removed owing to the mechanical action of the bal loon. Possible complications of this procedure include lesions to the inner wal l of the vessel (the "intima"). which can in turn give rise to thrombosis, dissect ion of the vessel with the obstruction ol^' arterial outflow (or in flow), pseudo-aneurism with the occurrence of pathological dilation of the vessel, rupture of the walls, distal embolism through the presence of atheromatous plaque, etc.

!n addition to this, with the surgical procedure it is very difficult to visual ise the extent of the area requiring treatment (very often this surgical procedure is performed in theatre without the help of a fluoroscopic guide and inlra-operalive angiography) and the surgeon has to use an assessment of the in- flow and out-flow of blood as a basis. There is also less selectivity as regards the section of artery which has to be treated, in that the catheter is pushed into the artery "blind", only following a centimetre scale on the Fogarty catheter; in this way there is no certain!)' that all the vessel a ffected by the pathological condition has been treated, neither is it possible to rule out that segments of vessel which have not been affected by the obstruction or col lateral vascular branches have also been treated. There is also a lesser possi bi li ty ot- making intra- and post- treatment checks and of remodelling the diseased arteries by angioplasty or stent i ng. i f necessary.

Surgery is always relatively highly invasi ve because of the dissection of the layers covering the artery, and therefore the subsequent surgical suturing and scarri ng. Also surgery becomes even more invasive if the embolism affects abdominal vessels (mesenteric arteries, coeliac artery, kidney arteries) or thoracic vessels ( pulmonary arteries, subclavian arteries) or cerebral vessels, with a significant increase in related complications. The main surgical complications affecting the access point include for example bleeding, fistula, infection, abscesses and pseudo-aneurism. In any event hospitalisation t imes are relatively long.

The procedure via the percutaneous route instead requires only local anaesthesia, w ithout any superficial or deep surgical incisions, drastically reducing the risk of local vascular, infection and scarring complications.

The procedure normally comprises access to the vascular system via a first needle which i s used to puncture the skin and the subcutaneous layers down to the selected blood vessel (for example an artery). A guide wire, which is used to sl idably guide a device known as an introducer comprising a hollow cannula and a fascial di lator projecting from the distal end of the cannula with a tapering tip, is introduced into the vessel through the needle, which is then removed. The fascia! dilator slides on the guide wire and is used to widen the passage through the tissues, following the guide wire so as to move the introducer inside the vessel together with the distal end which is positioned axially w ithin the vessel. The introducer may be of variable length and is moved within the vessel by the operator to a predetermined point. After the di lator has been removed, via the lumen of the introducer (provided with a suitable valve at the proximal end ) a eatheter is inserted inside the vessel and slid to the vessel section which must be operated on. In accordance with the usual techniques of surgical radiology, with percutaneous access to the vascular system (fluoroscopic guide using X-rays and injection of contrast medium for angiographic investigation), it is possible to monitor the route of the catheter and reach the obstructed section and pass beyond the thrombo- embolytic formation accurately and safely.

The mini-invasive percutaneous approach offers undoubted advantages, but also includes some limitations when accessing the blood vessel, which often leads surgeons to prefer the surgical approach, even though it is more complex and in some respects more risky.

The main obstacle is that because of the percutaneous access there are limitations on the maximum diameter of the instruments which can be inserted.

Depending on the nature of the surgery the catheter will be selected from various possible types.

For example there are various catheters specifical ly designed for the removal of embolisms via the percutaneous route. In the overwhelming majority of cases the technique provides for thrombo-aspiration of the clot through the catheter. In some devices this ihrombo-aspirating force is obtained by mechanical ly creating vacuum and suction, while in other cases the material is brought out by means of an endless screw which rotates within the catheter at thousands of rotations per second. Other devices may be used to remove thromboembolisms through mechanical thrombectomy, The most complex and bulky devices however need to be introduced into the blood vessel via a surgical operation, thus ruling out percutaneous access.

For example, US 4,729,763 describes a catheter comprising two concentric tubes, with the inner tube rotating axiallv to drive a mi ll at the distal end of the catheter. Thi s catheter is relatively large and a surgical operation is required in order to introduce it into the blood vessel that is to be treated.

Although in the meanwhile attempts have been made to reduce the diameter of the catheters used sti ll further, problems of miniaturisation and problems w ith the effectiveness of the device are often encountered. Furthermore when the catheter is small in size it becomes necessary to break up the clot before extraction or extract it together with the entire catheter after it has been trapped on the tip of the latter.

US 4.61 0.662 describes a treatment catheter which is inserted into a guide catheter coaxial ly. The treatment catheter comprises two inflatable bal loons located at the distal end of the catheter to trap and isolate the obstructing material in the section between the balloons. Ducts present in the catheter allow liquid to be circulated in the isolated section between the balloons with a view to attempting to dissolve and remove the obstructing material in small steps. The lumen of the catheter may thus be smal l, but the guide catheter must necessarily have a relatively large diameter because of the structure required to isolate the stenosis, and for circulation of the liquid.

US 2009/0.054.91 8 describes a removal catheter constructed to have a smal l diameter with a form-memory wire which slides axiallv within the catheter so as to exit with its tip from the distal end of the catheter and contract in the form of one or two coils when suitable energy is applied, in this way the end of the wire can move the clot by dragging it towards the outlet when the entire catheter is withdrawn, in one of the embodiments described tiie catheter has a distal end which can enlarge under control so as to trap the clot within it together with the expanded end of the wire, livery time anything is removed the whole catheter must be taken out to remove the clot trapped in the tip before it is possible to perform a second pass i f necessary.

US 5.01 1 .488 describes a catheter comprising three concentric flexible tubes. The intermediate tube has a distal end which opens against a spring when it leaves the distal end of the outer tube. The innermost tube instead has an inflatable bal loon at its distal end. The catheter can be introduced by means of a percutaneous introducer and pushed as far as the region of the clot which must be removed. The intermediate tube is then moved forward so that it projects and opens its end in the manner of a funnel, and the innermost tube is pushed beyond the clot and then inflated. By withdrawing the innermost tube the clot is drawn in towards the open end of the intermediate lube by the balloon and is trapped. The entire catheter is then withdrawn and taken out through the introducer so as to draw out the clot which remains trapped at the tip of the catheter. US 5, 1 02,41 5 describes a device comprising three concentric catheters - the outermost acts as an introducer and into this there is inserted an intermediate catheter provided with a distal end which can be controllabiv expanded into a funnel shape. The innermost catheter instead has a distal end on which a balloon can be inflated to draw the embolism which is to be removed into the expanded funnel-shaped end of the intermediate catheter. The external catheter protects the expandable lip as far as the region where the clot to be removed is located. The external catheter which acts as an introducer does however l imit the diameter of the intermediate catheter and the lumen of the passage w⁷ilhin it.

In an attempt to solve the problem of a small l umen for passage through a catheter. catheters or introducers which can expand radial ly over their entire length once ⁽hey have been inserted into position in a blood vessel have also been proposed in US2009/0240202 and WO201 0/ 1 1 91 1 0. This reduces the difficulty of moving the catheter along the blood vessel . On the other hand the blood vessel is negatively stressed along its entire length. These catheters are also complex to make, di fficult to use and may function unreliably. In addition to this, the need to provide a radial di lation mechanism in the catheter walls greatly restricts the possibility of enlarging the lumen for passage within the catheter through expansion, because the catheter walls are of greater thickness than normal.

However even if with these catheters it is possible to avoid excessive friction between the vessel wail and the calheier, in the case of introduction via the perculaneous route there is a limit on radial expansion due to the need to keep the diameter of the introducer sufficiently small. In fact not only is the maximum diameter of catheters l imited by the dimensions of the inner lumen of the introducer, but in turn the introducer itself must have a diameter which is commensurate with the diameter of the vessel and be sufficiently thin so as not to leave an excessively wide passage behind it when i t is extracted, so that there is no need to intervene surgically to suture the passage itsel f, something which would negate the advantages of the mini-invasive technique.

Essentially, known systems for application of the mini-invasive percutaneous technique are unsatisfactory.

The general object of this invention is to provide a more satisfactory system for percutaneous introduction into a duct of the body and a system for removing material from a duct (for example clots in a blood vessel ) which is simpler, faster and more efficient.

With this object in view the idea which has occurred is to provide an introducer device according to the invention for percutaneous introduction into ducts of the body comprising an outer tube having a distal end intended to enter percutaneously and slide within a duct in the body and a proximal end provided with a valve element with a leaktight axial passage in which there is removably housed a fascial di lator axial ly inserted into the tube through the passage of the valve element so as to project from the distal end with a tapering tip, characterized in that the distal end can be conlrollably moved between a rest condition and a radially expanded condition.

In order to provide a clearer explanation of the innovative principles of this invention and its advantages in comparison with the prior art. embodiments applying these principles will be described below with the aid of the appended drawings. In the drawings:

- Figure 1 shows a diagrammatic view- in partial cross-section of an introducer device according to the invention;

- Figure 2 shows a diagrammatic view of a distal end of the introducer in Figure 1 close to the area of entry into a duct, for example a blood vessel;

- Figures 3 and 4 show diagrammatic views of the distal end of the introducer according to the invention close to the material to be removed (for example a clot) and during removal of the material respectively;

- Figure 5 shows a diagrammatic view in transverse cross-section (along the l ine V-V in Figure 4) o f a possible embodiment of the distal end of an introducer according to the invention;

- Figures 6 and 7 provide diagrammatic perspective views of tw o possible alternative embodiments of the distal end of an introducer according to the invention;

- Figures 8 and 9 show diagrammatic perspective view s of a further possible embodiment of the distal end of an introducer according to the invention in the closed and open condition respectively.

With reference to the figures. Figure 1. il lustrates an introducer device according to the invention generically indicated by 1 0, comprising an outermost cannula or tube 1 1 with a distal end 1 2 that is intended to be introduced into a duct in the body ( for example in particular a blood vessel ) through percutaneous access, as will be clear below. The device may vary in length according to need (for example it may have a length of between 1 0 and 90 cm). Advantageously the introducer will be of cyl indrical shape so that it can be introduced into ducts such as an artery, like a conventional vascular introducer.

Preferably the introducer will have the generic structure of a tubular body which is substantially known to match the path within the ducts without crushing. For example it may have a core of variable/resilient shape made of a suitable known material (e.g. nitinol) and covered with a known resilient biocompatible and noivthrombogenic material (e.g. PVA. PIPE, etc.).

At the proximal end 1 5 the introducer comprises a body 1 9 which is useful for gripping and manoeuvring and which is provided with an axial passage 20 towards the tube 1 1 . The passage 20 is lilted with a known lcaktight passage valve element 1 4 ( for example with a pierced resi lient membrane) to avoid the loss of fluid to the exterior once the introducer has been inserted in the duct of the body, but which allows the introduction of catheters and instruments through the passage 36 and into the lumen of the introducer.

The introducer also comprises a fascial di lator 1 3 which is axially inserted into the cannula 1 1 through the passage of the valve element 1 4 present at the proximal end 1 5 of the device. The fascial dilator is constructed so as to slide (preferably with minimum play) within the tube 1 1 and project from the distal end 1 2 with its tapering end 1 6. The fascial dilator 1 3 advantageously has an axial passage so that it can slide on a guide wire 1 7.

The distal end 1 2 o f the introducer can be controllably di lated so as to pass from its closed rest condition to a radially expanded condition, advantageously of conical shape with a distal base.

In the closed condition the tip preferably has a diameter which is substantially the same as the diameter of the cannula so that it substantial ly adopts the shape of a cyl i nder, such that the introducer can be introduced, retracted and removed without trauma.

The (manual) control device for the movement is arranged so that it can be operated from the exterior once the introducer has been placed in position. Advantageously this control device comprises operating means 1 8 located at the proximal end 1 5 ( preferably on the body 1 9 or connected to the body 1 9), as will be clearly apparent below.

The distal end 1 5 may also comprise a connector 35 which is connected to the lumen of the cannula 1 1 and to which a flexible tube 36 for the introduction, where necessary, of l iquids into a blood vessel/duct is connected.

Particular reference will be made below to the use of the device according to the invention which is suitable for percutaneous introduction into a blood vessel . As will be clear from what fol lows, it is however to be understood that the principles of the invention can be adapted to other ducts in the body (such as for example the bi le ducts, those in the urinary system, the ducts in the digestive system, etc .).

Figure 2 shows a diagrammatic illustration of percutaneous entry of the introducer into a blood vessel 21 . The insertion manoeuvres may be the same as those performed with an introducer of the known art and will not therefore be described and il l ustrated in detail here, as they can be easily imagined by those skil led in the art. The tube 1 1 of the introducer is the outermost element of the device, in direct contact with the walls of the passage in the patient's body and the interior of the blood vessel.

For the purposes of introduction essentially a needle (not show n) may be fi rst introduced until it is inserted into the vessel 21 and the guide wire 1 7 can be inserted into the blood vessel/duct through this needle.

Once the needle has been removed, the introducer complete with the fascial di lator may^¬ be slid along guide wire 1 7. With the aid of the dilator the introducer penetrates the subcutaneous, fascial and muscular tissues perculaneously and then enters the blood vessel/duct. As il lustrated diagrammatically in Figure 2. the introducer complete with di lator is made of a sufficiently ilexible material for it to be able to follow the wire and position itself with the end of the tip parallel to the axis of the vessel .

Once inserted with the tip parallel to the axis of the blood vessel, the introducer is then sl id along its entire length until it reaches the desired point in the vessel. Figure 3 shows the introducer with its distal end (after the fascial dilator has been removed) lying c lose to material 22 which has to be removed (for example a clot).

Once the introducer is in position the distal end is set to its radially dilated condition ( shown in dashed l ines in Figure 3 ) so that the edge of its free end is close to the walls of the vessel and forms a kind of funnel which will intercept the material which will be removed.

In order to effect removal, the device may advantageously comprise a sl iding element ( indicated diagrammatically by a line at 35 ) with an expandable end 23. For example this sliding element may be a suitable catheter which is in itself known. The element is introduced via the introducer until it passes beyond the material which has to be removed and when expanded can be drawn back within the lumen of the introducer, pull ing the material along the entire length of the introducer to the proximal end until i t comes out of the leaktight valve 14 (which may be designed with a known screw mechanism so that it can be unscrewed and screwed up again and thus allow the obstructing material to leave the introducer freely). It is thus possible to perform for example several cleaning operations and/or introduce sequentially other types of catheters or instruments without having to remove the introducer.

As shown in Figure 4, the expandable end 23 wil l advantageously be selected from a type which is capable of being sufficiently compressible, even when in the expanded or partly expanded condition, so as to deform as the material passes into the funnel-shaped end 1 2 and so that it can travel along the introducer to the proximal exit. In this way it can carry the clot through the introducer to the exterior, minimising the risk of loss of the material which has to be removed along (he way. Advantageously the funnel shape of the distal end of the introducer assists insertion and compression of the part 23 inside the lumen of the introducer.

It has been found particularly advantageous if the element 35 with expandable end is a "Fogarly type" balloon catheter. Normally, this type of catheter is used for surgical embolectomy. but thanks to the innovative characteristics of the introducer according to the invention it may also be advantageously used percutaneously (when for example it is decided to use the abovementioned Fogarty catheter sliding on a guide wi re ).

Using techniques which are known per se and which can easily be imagined by those skilled in the art, the balloon 23 is placed in a position beyond the material or clot 22. passing through introducer and material 22 in the unintlated state, then being inflated so that the material is confined between the balloon and the funnel of the expanded distal end 1 2. Retraction of the balloon along the introducer draws the material to the exit 1 5. again as il lustrated in Figure 4.

Once the operation through the introducer has been completed, the distal end 1 2 may be returned to its rest condition and the introducer can finally be removed from the duct. A known haemostatic procedure may then also be applied if this is necessary or appropriate.

Figure 5 shows a possible structure of end 1 2 which permits movement between its two conditions. This structure advantageously comprises a plurality of fingers or blades 24 extending longitudinally at the distal end of the introducer. The fingers may advantageously comprise a form-memory material such as nilinol.

Between lingers 24 there is preferably a flexible membrane 25. with a resilience and/or a size selected so that end 1 2 can expand between the closed cond ition and the expanded condition in an "umbrella" movement, as is clear from Figure 5. Use o f the membrane allows the tip 1 2 to safely intercept the material which is to be removed also avoiding the latter becoming lodged between the open blades. The membrane may for example be of made PTFE. a porous and strong material, or the l ike.

When the device is in its closed state the membranes advantageously fold inw ards.

The mechanism for opening/closing the tip may be constructed in various ways.

For example in Figure 6 (in which membranes 25 are not shown for c larity ) an embodiment operated by a pull-wire is il lustrated diagrammatical ly. In this embodiment, the lingers are constructed so as to open resilientiy towards the cone condilion, preferably as a result of their natural resil ience. A loop 26 of suitable wire is arranged circumferential))' on the fingers. As will be readily imagined by those skilled in the art on the basis of the description of the invention provided here, suitable passages and/or grooves (not shown) may be provided to prevent the loop from sliding along the axis of the introducer.

A pull-wire 27 extends, advantageously within a passage made withi n the thickness of the wall of the introducer, as far as the device 1 8 (for example comprising a simple handle for pulling the pull-wire).

By pulling the pull-wire 27. the loop 26 is caused to tighten, thus bringing the lingers together into the rest condition of the end 1 2.

By releasing the pull-wire the resilience of the fingers returns the tip to the expanded funnel-shaped condition.

A known Socking system may advantageously be provided in the device 1 8. so that it is possible to keep the pull-wire under tension and the end 1 2 is in the rest condition shown in Figure 3 during the operations of introducing, moving and extracting the introducer.

Figure 7 shows a second possible embodiment of the mechanism for moving the end 1 2. In this second embodiment a fluid system is used to inflate the distal end into its expanded condition. In this case an inflatable chamber placed in the distal end w hich expands the distal end radially on command is advantageously provided. This inflatable chamber is advantageously shaped in the manner of an in flatable ring 28 located coaxial ly on the end 1 2.

i n particular the end preferably again comprises lingers 24 (for example agai n made of nitinol ) constructed so that they are normally resilient!y pushed into the closed-up rest condition (for example as a result of their natural resi l ience) when the ring 28 is deflated. As will be clearly seen in Figure 7. inflating the ring increases the d iameter in such a way that it moves the edge of the distal end away (and in particular the extremities of the fingers, if present) and produces the conical shape of the funnel . When ring 28 is deflated, the end 12 of the introducer returns to its cylindrical rest condition.

Also in this second embodiment the membranes for closing off the space between the open fingers, as described above, may be present between lingers 24.

The ring can be inflated and deflated by means of a condui t 29 w hich is advantageousl y made in the thickness of the wall of the introducer and extends as far as device 1 8. which is constructed as an inflation/deflation system (for example comprising a simple known small pump with a deactivalable one-way valve or a known syringe system ). The ring is inflated or deflated by the operating device 1 8. The deflating operation may also possibly comprise a suction force. Advantageously inflation may take place using a physiological solution as fluid.

Figure 8 shows a third possible embodiment of the mechanism for moving the end 12. I n this third embodiment the expandable end 1 2 comprises a foil element 30 wound along the axis of the introducer in tube form. An edge 3 1 of the foil may be pushed in a direction (advantageously substantially axially to the extension of the tip ) so as to move the overlapping lateral edges of the foil in such a way that it is arranged from the cylindrieally rolled form into a conically rolled form, as is clear from Figure 9.

Advantageously a resilient force acts on the foi l element so as to press it towards the conical condition in Figure 9. while a pull-wire 33 (similar to pull-wire 27 in Figure 6 ) can be operated to draw the tip back against the resilient force into the condition in Figure 8. The resilient force which pushes towards the condition in Figure 9 may be for example provided by means of a spring 32.

A resilient force produced by foil 30. suitably constructed so as to resil iently maintain the shape in Figure 9 when in the rest condition, may also be used direct!}' instead of the spring. For example the foi l may be formed w ith a resilient and suitably shaped thin sheet of suitable material (such as nitinol ).

The pul l-wire may also be constructed using a wire which is sufficiently axially rigid so that it can be used to both push and pull. In this case the resilient action on the foi l may no longer be necessary.

A membrane (not shown) which seals the spaces for sliding of the foil sides may also be provided so as to prevent the clot formation from entering the sliding spaces during pulling inside the device.

At this point it is clear how the stated objectives may be achieved by modi fying the structure of the introducer, and not the structure of the catheter (according to the approach of the prior art).

The introducer with the innovative capacity to widen progressively from the distal end and thus come into contact with the walls of a duct, in the body, adopting a cone/funnel shape, allows for example the use of a " Fogarty on guide" type balloon catheter, ^'i his balloon catheter may channel the material to be removed within the i nnovative introducer and therefore remove it wholly outside, even in several passes, without unnecessarily stressing the site of percutaneous insertion.

Furthermore because the introducer is used directly to produce the expanded end conveying the material to be removed, it is possible to have a relatively large through- lumen, while keeping the external diameter of the introducer itself small ( for example about 6-8- 10 French, where 1 French = 0.33 mm). This makes it possible to work safely percutaneously whi le having different lumens for both access inside the duct and removal of the material . Also the fact that the introducer is able to expand in order to come into contact with the wall of the duct, a high stability of the distal end of the introducer may be achieved, even when a long introducer is used.

Throughout the procedure it is possible to use an angiographic guide which may remain downstream of the obstructed section, so that the operation can be repeated as many- times as necessary until satisfactory clearance is achieved. I njections of contrast medium may also be made through the introducer to al low intermediate and final angiographic investigations.

As already mentioned above, the appl ications of the device according to the invention are not l imited to the removal of clots but, owing to the innovative funnel concept, the device may be used for other purposes (such as the treatment of pre-angioplasty and pre-stenting arterial stenoses, the removal of foreign bodies, or the like) and be used in other ducts in the human body - for example in the system of the liver's bile ducts, for the removal of fonnations within the ducts such as calculi or removable stents, or in the urinary system in ducts such as the renal pelvis, the ureter and the bladder, and again in the ducts and conduits of the digestive system.

The device to which the invention relates offers another important aid and characteristic as a result of the funnel-shaped opening of the introducer. In fact, as described previously, in this funnel configuration the walls of the distal end of the introducer may be dimensioned so as to come into contact with the walls of the duct in which it is placed ( venous or arterial blood vessel, bile duct, duct in the urinary system, etc. ) . Contact with the wal l of the duct makes it possible to slow the passage of fluids in the duct, in particular, contact with the wall of a vessel, for example an arterial vessel, significantly reduces the passage of blood beyond the introducer.

This special feature offers for example the advantage of being able to carry out all the stages of removal (of a clot for example) with virtual blockage of the flow, significantly reducing the risk of the migration of micro-embol isms and embolisms carried into more distal vessels by the blood flow. In addition to this, once satisfactory stasis of the How in the vessel/duct section beyond the distal end of the introducer has been confirmed, drugs may be administered through the introducer itself in order to achieve a high concentration and selectivity o f the drug in the area of the vessel/duct undergoing treatment.

In the case of clots, a thrombolytic/fibrinolytic drug may for example be injected into the area between the distal end of the introducer with an open tip and the removing device ( in particular the Fogartv balloon inflated downstream of the clot formation ). I n this condition the thrombolytic drug may act in high concentrations within the vessel in which the clot has formed, reducing systemic dispersion of the thrombolytic drug, as well as possible systemic complications associated therewith.

In fact, after a predetermined time, most of the drug which is injected and trapped between the introducer and for example a Fogartv balloon could be partly sucked out through the introducer so that it is then possible to proceed wish the procedure for removal of the clot as described previously. In this arrangement, therefore, there is the possibil ity of pretreating the clot formation to be removed.

Other drugs and other indications could make good use of the capacity of the introducer device to induce stasis in flows downstream of its open tip and in contact with the wal l of the vessel/duct, as can now be readi ly imagined by those skilled in the art .

With the solution according to the invention it is advantageously possible to combine the major advantages of the mini-invasiveness of the percutaneous access technique with the confirmed efficacy of the Fogartv catheter for pul ling out and removing materials such as thrombo-embolic formations in a surgical context.

However, owing to the principles of the invention, other removal systems such as for example systems with nitinol cages, which may be more defbrmable. less traumatic for the walls and have less adherence to the walls of the introducer, may also be used instead of " Fogartv type" balloon catheters.

Owing to the device according to the invention, there is better selective treatment of the pathological section of the duct, fewer complications at the access site, fewer infectious complications, shorter hospitalisation times for the healing of wounds, fewer surgical complications in general, increased selectivity of treatment, increased control i n handl ing of the removal system, with the possibility of visualising and monitoring it over its entire path, and the possibility of also approaching smal l ducts and vessels { for example the distal vessels of the leg or the forearm) and more tortuous vessels (e.g. the anterior tibial, the splachnic vessels, etc.).

Obviously the above description of an embodiment applying the innovative principles of this invention is provided by way of an example of such innovative principles and should not thereby be considered to limit the scope of the right claimed here.

The system for expansion o f the tip of the introducer ma}' di ffer from those described here.

Also, given the special features of the device, an inner space which is greater than what is normal when in the closed condition may be occupied in its distal part (for example because of the folded membranes and/or the opening/closing mechanisms). In this case the fascial dilator may be thinner ( for example hol!owed-out) in its distal part corresponding to the distal section of the opening funnel (as shown diagrammatical !}' in dashed l ines with 37 in Figure 1 ) so as to leave space within the introducer for parts o f the end 1 2 in the rest condition (in particular for the membranes). A hol lovved-oui form of the dilator before its conicallv tapered part may also be useful for axially constraining the fascial dilator to the introducer until the moment when the conical end of the introducer is opened.

Claims

1. Introducer device (10) for percutaneous introduction into ducis in the body, comprising an outermost tube (11) having a distal end (12) intended to enter percutaneous!}' and slide within a duct, and a proximal end (15) provided with a valve element (14) with a leaktight axial passage (20), which removably houses a fascial dilator (13) inserted axial ly in the tube (11) through the passage of the valve element so as to project with its tapering end (16) from the distal end (12), characterized in that the distal end (12) can be controllabiv moved between a rest condition and a radially expanded condition.

2. Device according to Claim 1, characterized in that in its radially expanded condition the distal end (12) has a substantially conical shape with a distal base.

3. Device according to Claim 1. characterized in that operating means (18) which are connected along the tube ( 11 ) as far as the distal end ( 12) are present in or connected to the proximal end (15) in order to control the movement of the distal end (12) between the rest condition and the expanded condition.

4. Device according to Claim 3. characterized in that the connection between the operating means (18) and the distal end (12) is provided by means of a pull-wire (27.33) or by means of a conduit with control fluid (29).

5. Device according to Claim 1, characterized in that the distal end (12) comprises a plurality of lingers (24) which can move between the rest condition and the expanded condition.

6. Device according to Claim 5, characterized in that a connecting membrane (25) is located between the fingers (24).

7. Device according to Claims 3 and 5, characterized in that the fingers (24) are held in the expanded condition or in the rest condition by means of a resilient force and operating means (18) are controllabiv operated against the said resilient force so as lo move the fingers (24) from the resiliency maintained condition to the other rest or expanded condition.

8. Device according to Claims 4 and 5, characterized in that the fingers (24) arc resiliently kept in the expanded condition and the operating means control a loop (26) positioned around the plurality of fingers (24) and thai when the pull-wire (27) is pulled it tightens so as to close the fingers (24) towards the rest condition.

9. Device according to Claim 4. characterized in that an inflatable chamber (28) containing a fluid for expansion of the distal end towards its radially expanded condition is present at the distal end.

10. Device according to Claim 9. characterized in that the chamber (28) is ring-shaped and coaxial with the distal end.

11. Device according to Claims 5 and 9. characterized in that the chamber (28) is connected to the fingers (24) in such a way that, when it inflates, it moves the fingers towards the radially expanded condition.

12. Device according to Claim 1, characterized in that the distal end (12) comprises a foil element (30) rolled up axially at the distal end with an edge (31 ) which is slid so as to cause the foil to pass from a cylindrical! y rolled condition corresponding to the rest condition of the distal end to a conicallv rolled condition corresponding to the expanded condition of the distal end,

13. Device according to Claim 12, characterized in that the foil element (30) is acted on by a resilient force which pushes it towards its conicallv rolled condition and a pull-wire (33) which controllably pulls the edge against this resilient force so as to bring the element into its cylindrical!}' rolled condition.

14. Device according to Claim 13, characterized in that the resilient force is produced by a spring (32) located close to the distal end.

15. Device according to Claim 1. characterized in that it comprises a sliding element (35) with an expandable end (23) and that, once the dilator has been removed, it can be introduced via the proximal end (15). slid inside the tube (11) so as to exit from the distal end (12) with its expandable end (23). and retracted again inside the distal end (12) in a radially expanded condition so as to allow removal of material in the duct, such as in particular clot formations in a blood vessel.

16. Device according to Claim 15. characterized in that the sliding element (35) is a "Fogariy" type balloon catheter.

17. Device according to Claim 15. characterized in that the fascial dilator (13) is thinner in the region of the distal end (12) in order to house within it parts of the distal end ( 12) in a rest condition.