"DEVICE FOR TREATING ARTERIAL OCCLUSIONS OF THE LOWER LIMBS"

The present invention refers to a device for treating the lower limbs, in particular for treating chronic arterial occlusions.

Chronic arterial occlusions of the lower limbs are a common cause of ischemia and often lead to amputations. Peripheral angioplasty procedures have the purpose of reopening the vessel, reaching the true lumen of the vessel downstream of the occlusion and re-establishing a normal blood flow.

According to a prior art (called endoluminal technique) , to treat the vessel a vascular catheter is used, inside which a suitably flexible metallic guide is moved forward until it reaches the arterial occlusion. With the nib of the guide it is then attempted to pass through the occlusion, to then make a balloon advance on the guide and re-open the occluded vessel; thereafter, a stent is possibly applied. However, in the case in which the occlusion is hard, of a calcified nature, it is not possible to perforate it with the nib of the guide, due to its flexible nature.

In such a case, it is known to use other devices which enable the occlusion to be passed in the subintimal space of the vessel, or rather, inside the vessel wall. These devices comprise a needle with a flexible nib and a tubular body provided at the distal end with suitable deflection means of the needle nib. The tubular body is moved forward through the vessel until it reaches the subintimal space of the vessel at the height of the chronic

occlusion, exploiting, for example, a metallic guide inserted into the vessel. The deflection means of the needle are positioned immediately downstream of the occlusion in the subintimal space of the vessel. The needle with flexible nib is therefore moved forward inside the tubular body until it reaches the deflection means, which bend the nib of the needle, pointing it towards the true lumen of the vessel downstream of the occlusion. Once the true lumen has been reached, balloons, stents or other items intended to re-establish the normal blood flow, can be used.

The structure of this device, needing a tubular body provided with needle deflection means, is particularly complex and costly. Moreover, the device cannot be used efficiently with an endoluminal approach, due to the flexibility of the needle end, as well as to the presence of the deflection means.

The general purpose of the present invention is to avoid the aforementioned drawbacks by providing a device which allows chronic lower limb artery occlusions to be treated effectively with both an endoluminal approach as well as with a subintimal approach.

A further purpose of the invention is to provide a device with a simple structure and which is cost-effective. In view of such a purpose it has been thought to make, according to the invention, a device for treating lower limb artery occlusions comprising a tubular element intended to be inserted into the artery to be treated, the tubular element being provided with a proximal end able to be maneuvered by a user, an intermediate portion and a distal end opposite the

proximal portion, characterized in that the intermediate portion and the distal end of the tubular element have an outer diameter of between 0.4 mm and 1.2 mm, said distal end being made stiff so as to not deform during the treatment and being provided with a nib suitable for perforating the vessel tissue, with there being an opening near to the nib which places the inside of the tubular body in communication with the outside. In order to clarify the explanation of the innovative principles of the present invention and its advantages with respect to the prior art, hereafter, with the help of the attached drawings, we shall describe a possible embodiment given as an example applying such principles. In the drawings : - figure 1 represents a view of a patient with chronic lower limb artery occlusions;

- figures 2 and 3 represent views of the patient treated with a device according to the invention;

- figure 4 represents a view of a catheter to be used for treating the chronic occlusion;

- figure 5 represents a view of one embodiment of the tubular element of the device according to the invention;

- figure 6 represents a view of the tubular element inserted into the respective catheter, with part of the catheter removed; - figure 7 represents a view of the tubular element inserted into the catheter with the distal end projecting out in front of the catheter;

- figure 8 represents a detailed view of the distal end of

the tubular element of the previous figures,-

- figure 9 represents a perspective view of the nib of the tubular element;

- figures 10 and 11 represent two side views of the nib of the tubular element;

- figures 12-17 represent the steps of a classic endoluminal approach for treating a vascular occlusion;

- figures 18-23 represent the steps of a subintimal approach for treating a vascular occlusion; - figures 24-28 represent a further use of the device for injecting drugs and substances into the subintimal and perivascular spaces;

- figure 29 represents a perspective view of the tubular element inserted into the catheter; - figure 30 represents an alternative embodiment of a device according to the invention;

- figure 31 shows a side view of an alternative embodiment of the nib of the device;

- figure 32 shows a side view in section of the nib of the device of the previous figure;

- figure 33 shows a side view of a further alternative embodiment of the nib of the device .

With reference to the figures, in figure 1 a patient 11 is shown supine on the angiographic table, where the vessels 12 of the lower limb 13 are schematically represented, with a chronic occlusion 14 located at the superficial femoral artery, and chronic occlusions 15 at the fibular and posterior tibial artery. Through anterograde femoral puncture, the device 16

for the treatment of lower limb arteries is alternatively- positioned level with the chronic occlusions 14 or 15 (figures 2 and 3) .

The device 16 comprises a tubular element 18 suitable for being moved forward in a catheter 17 inside the vessel to be treated. The catheter 17 itself can be made according to known techniques (figure 4), and it can comprise a flexible tube 17a the end of which is fixed to a conical element 17b provided with an opening 17c suitably widened to facilitate the insertion of guides and/or needles inside of it.

As clearly shown in figures from 5 to 7, the tubular element 18 comprises a proximal end 21 able to be maneuvered by the user, an intermediate portion 20 and a distal end 19. The intermediate portion 20 is made with sufficient flexibility so as to follow the typical curves of the artery vessels of the lower limbs of the patient. The distal end 19 is stiff so as to not undergo substantial deformation during the treatment . At the proximal end 21 a "luer lock" type connector element 22 is advantageously foreseen, which allows a syringe to be rapidly connected to inject a drug or radiological contrast medium, or to draw out blood.

The connector element 22 comprises a fin 22a which indicates the orientation of the distal end 19 of the tubular element 18, and has a conical cavity 35 which allows the nib of a guide to be easily inserted into the tubular element. The intermediate portion 20 of the tubular element 18 and the distal end 19 can advantageously be made from steel, with the

same constant cross-section along their entire longitudinal extension. The outer diameter of the portions 19 and 20 is between 0.4 and 1.2 mm, preferably equal to around 0.7 mm. The inner diameter of the portions 19, 20 can be between 0.2 mm and 1.0 mm, preferably between 0.40 mm and 0.50 mm, to allow conventional guides having a diameter of 0.36 mm or 0.46 mm to be inserted.

The total length of the tubular element 18 is between 20 cm and 120 cm, preferably equal to 105 cm, and in any case greater than the length of the catheter 17 so as to allow the end 19 to come out from the catheter.

According to a preferred embodiment of the invention, the distal end 19 comprises an angled segment 19a, clearly represented in figure 8. The angled segment has a length L of between 2 and 38 mm, preferably equal to about 12 mm. The inclination a. of the angled segment 19a with respect to the axis of the tubular element is less than 45°, advantageously equal to about 15°. The distal end 19 ends with a nib 23 that is provided with an opening 30, which places the inside of the tubular body 18 in communication with the outside (fig. 9) . The nib 23 has an acutely pointed shape, to allow the wall of the vessel in need of treatment to be perforated (in the case in which a subintimal approach is adopted, as shall be followed up hereafter) or to make it easier to get passed the chronic occlusion (endoluminal approach) . According to an embodiment of the invention (figs. 9-11), the opening 30 is formed on the nib 23 which is cut according

to the main section plane 32 inclined by an angle y with respect to the axis of the angled segment 19a of between 15° and 60°, preferably equal to 25°. The most advanced edge 31 of the nib 23, if seen from the side, is cut according to a surface 33 inclined by an angle β with respect to the axial direction of the angled portion 19a of between 10° and 45°, preferably equal to about 25°.

The angle α and the angle γ are selected with opposite signs so that the most advanced edge 31 of the nib 23 is not as aggressive on the inner wall of the catheter 17 (see figure 8) , and the sliding of the tubular element 18 in the respective catheter is thus made easier.

The two angles γ and β are selected, on the one hand, to allow the possibility of perforating the wall of the vessel or the chronic occlusion and, on the other hand, to prevent the wall of the catheter from being perforated in the forward movement step.

In figure 29 the device 16 is shown, with the tubular element 19-21 inserted into the catheter 17. In the figure it is also shown how by rotating the proximal end 21 of the tubular element, it is possible to orientate the distal end 19 according to one's desire, exploiting the connector 22 provided with the ribbing 22a. In figure 30, an alternative embodiment of a device 116 according to the invention is shown, in which the elements corresponding to elements of the embodiment of figures from 4 to 7 are indicated with reference numerals raised by 100. The device 116 differs from the first embodiment in that the

distal end 119 of the tubular body is rectilinear, instead of being angled.

Figures 31 and 32 show an alternative embodiment of the tubular element which only differs from those previously described for the configuration of the distal end 219. The nib 223 is closed and has a pointed ogive shape, whereas the opening 230 which places the inner lumen of the tubular element in communication with the outside is formed on the side wall of the distal end 219, always near to the nib 223. Advantageously, the opening 230 is separated from the nib 223 by a distance of between 2 and 14 mm.

Figure 32 shows how a surface, able to. help a conventional guide 40 to exit the tubular body through the opening 230, is foreseen at the nib. Figure 33 shows a further alternative embodiment of the tubular element, in which only the shape of the nib 323 is modified with respect to the embodiment of figure 31. Also in this case, the opening 330 is formed on the side flank of the distal end 319 of the tubular body. However, the nib 323 is not ogive shaped, but has a conical shape, defining an acute angle .

These configurations of the distal end of the tubular body can make the nib less aggressive towards the catheter, whilst maintaining a satisfactory ability to perforate occlusions or blood vessels.

The device described above can only be used in procedures carried out through anterograde femoral approach, and so it is not possible to use it during so called contralateral

procedures . In the anterograde femoral approach the femoral artery is pricked at the groin and an introducer is inserted into it, directed towards the periphery, i.e. towards the superficial femoral artery. Hereafter, three different possible uses of a device according to the invention are illustrated.

1 ^st TYPE OF USE: PASSING CHRONIC OCCLUSIONS OF THE LOWER LIMBS ENDOLUMINALLY . Arterial occlusions of the lower limbs are often treated with percutaneous angioplasty procedures. Figure 12 shows a vessel 12 occluded by the chronic occlusion 14.

The standard technique of angioplasty consists in moving a vascular metallic guide 40 forward inside the vascular lumen. When the nib of the guide has reached the proximal end of the occlusion 14, it is attempted, with the coaxial support of vascular catheters 17, to move the nib of the guide 40 forward through the material 14 which occludes the vessel (see figure 13) . The purpose of this maneuver is to reach the pervious lumen 41 of the vessel 12 immediately downstream of the occlusion 14. If the guide 40 manages to pass through the occluded segment, the procedure continues with the insertion of balloon catheters coaxial with the guide which are dilated at the occluded segment making it reopen. The treatment can be completed with a stent implant. If, however, the material 40 occluding the vessel 12 is hard and calcified, it may be the case that the guide 40 is unable to pass through it, thus bending and deflecting, without moving forward correctly (see figure 14) . In the case

in which the guide fails to get passed the occlusion 14 according to the conventional method, a device according to the invention is used. The tubular body 18 thus replaces the guide inside the support catheter 17, the nib 19 of which is oriented by the user through the occlusion (see figure 15) . By delicately maneuvering the proximal end 21 of the tubular body 18, the operator moves the nib 23 of the tubular element forward inside the material 14 which is occluding the vessel 12, directing it towards the distal true lumen 41. When the needle has passed the occlusion and has reached the distal pervious true lumen (fig. 16), the operator can become aware of this by drawing blood through a syringe connected to its proximal end 21 of the tubular element 18, and test it by injecting radiological contrast medium, again through the tubular body 18 with an angiographic visualization of the pervious vessel downstream.

At this point, once it has been confirmed that the occlusion has been passed and that the nib 23 of the tubular element 18 is in the right position, a vascular guide 40 having a suitable diameter is made to pass through the tubular element 18 and moved forward as usual in the vessel downstream (fig. 17) . The guide used in this step could also not be the same as the guide used initially in the steps of figures 12-13, but having a smaller diameter. Hereafter, the tubular element 18 is withdrawn in the catheter 17 and the whole thing is withdrawn, leaving the guide 40 in place . The procedure proceeds in the usual way moving forward along the balloon catheter guide etc.

2 ^nd TYPE OF USE: RETURNING FROM THE SUBINTIMAL SPACE INTO THE VASCULAR TRUE LUMEN.

When the occlusion is very long and the occluding material is hard and calcified, the classic endoluminal way of passing the occlusion can fail, even using a device according to the invention.

An alternative approach consists of passing the occluded portion 14 passing alongside of the occluding material, in the so called "subintimal" space, or rather, inside the vessel wall 12. Like for the endoluminal approach, a conventional catheter 17, guide 40 system is moved forward in the pervious lumen of the vessel to the occlusion 14, then it is attempted to penetrate from the edge of the occlusion into the vessel wall, trying to find a plane with less resistance which can be dissected downstream (see figure 19) . The guide 40 is made to penetrate into this said subintimal space and moved forwards laterally to the occluded vessel portion

(see figure 20) . When the guide has passed the occluded segment, it is in the vessel wall, immediately on the side of the distal pervious true lumen. At this point of the procedure it is necessary to enter back into the true lumen by perforating the wall which separates the subintimal space, in which the guide 40 is moved forwards, from the pervious lumen 41 of the vessel 12. The catheter 17 which supported the guide 40 is not changed, but is moved forwards until it reaches the suitable point for entering back into the true lumen 41 (fig. 21) ; then the guide 40 is taken off and is replaced with the tubular

element 18. By delicately maneuvering the proximal end of the tubular element 18, the operator directs the nib 23 so as to penetrate into the true lumen 41. When the tubular element 18 has passed the intimal wall and has reached the distal pervious true lumen 41, the operator can become aware of this by drawing blood through the tubular body 18, into the syringe connected to its proximal end 21 and test it by injecting contrast medium, again through the tubular element 18 with angiographic visualization of the pervious vessel downstream. At this point, once re-entry from the subintimal space to the true lumen has been confirmed, a vascular guide 40 with suitable diameter is made to pass through the tubular element 18 and moved forwards in the vessel downstream (fig. 23) . Then, the tubular element 18 is withdrawn into the catheter 17 and the whole thing is withdrawn leaving the guide 40 in place. The procedure proceeds in the usual way by advancing balloon catheters etc. along the guide. 3 ^rd TYPE OF USE: INJECTION OF DRUGS AND SUBSTANCES IN THE SUBINTIMAL AND PERIVASCULAR SPACES.

When drugs or substances (for example, angiogenetic stem cells) are wished to be injected into the subintimal or perivascular spaces, the injection position is reached through the conventional guide-catheter system, then the guide is replaced with the tubular element 18 inside the catheter 17, with the nib 19 projecting from the end of the catheter. By delicately maneuvering the proximal end 21, the operator directs the nib 23 of the tubular element 18

so as to perforate the wall of the vessel and enter into the subintimal or the perivascular spaces (figures 24 and 25) . At this point, using the syringe connected to the proximal end 21 of the tubular element 18 it is possible to carry out small drug injections 50 (see figure 26) . It is also possible to move the tubular element 18 forwards into the perivascular space and carry out multiple injections along the best path, according to the operator, for the drug or injected substance to take effect (fig. 28) . This procedure can be carried out both in pervious vessels and in occluded vessels (fig. 27) .

At this point it is clear how the purposes of the present invention have been reached. In particular, a device for treating arterial occlusions of the lower limbs is provided, having a simple and cost- effective structure compared to the prior art. Moreover, the device according to the invention can be used effectively both with an endoluminal approach and a subintimal approach. Of course, the description above of an embodiment applying the innovative principles of the present invention is given as an example of such innovative principles and therefore must not be taken to limit the scope of protection hereby claimed.