FR2591900A1 - Device for the retention of clots, and ancillary introduction and release device - Google Patents

Abstract

The invention relates to a device for the retention of clots, intended to be introduced into the circulatory system of a human being, of the type comprising a central core and a set of metal spokes, fitted at their end with fastening means. The device according to the present invention is noteworthy in that the central core consists of a mass, of symmetrical shape, and in that the metal spokes are fitted at their ends with spikes. Application: human medicine.

Description

 Clot retention device, and ancillary device for introduction and release.

 The present invention relates to a clot retention device, intended to be introduced into the circulatory system of a human being, of the type of those comprising a central core and a set of metal spokes, provided at their end with fixing means. .

 The invention relates to human medicine, and more specifically the treatment of circulatory conditions, in particular pulmonary embolism.

 Pulmonary embolism results from the migration into the pulmonary arteries of a blood clot, most often originating in the veins of the lower limbs or the pelvis. The clots (in Greek, "thrombos") then migrate to the pulmonary arteries passing through the inferior vena cava, then through the heart.

Depending on the importance of the embolism, there are clinical pictures of varying severity, ranging from simple chest pain to certain death. But even minimal, a pulmonary embolism is a serious illness.

 The retention of the clot (s) between the place of its formation and the heart and the lungs has been known and practiced for a very long time, but with different means depending on the times and the state of advancement of medicine.

 The oldest technique is to link the inferior vena cava. Then, the Man of the Art imagined to pose a clip often in teflon, under general anesthesia, on the responsible blood circulation path, typically on this same lower vena cava. This technique was developed in the 1960s, and reported for example by ADAMS and DE WEESE. Its major drawback is the need for general anesthesia that is difficult to practice in the elderly, debilitated people, whose cardio-respiratory function is compromised.

 In the years 1965, appeared in the United States of America a more advanced technique called the filter-umbrella of MOBIN-UDDIN and which is described in particular in the patent US 3,540,431. This umbrella filter (11) as described with reference to Figure 1 consists of six spokes (or ribs) (12), made of a cobalt-chrome alloy, connected at their central end by a metal cap (13) and terminated at their second end by a point (14), and between which is disposed a thin layer of an elastomer (15), in the manner of an umbrella, except that said layer is pierced with several holes (16), with a dimension close to 3 mm, so as to let the blood flow through.

The metal cap is embedded in a silicone hemisphere (17) in which is provided a threaded hole for fixing to the ancillary introduction device.

The introduction of this parasol filter into the patient's circulatory system is widely described in scientific articles, and the article entitled "Transvenous Caval" will be cited for reference.
Interruption with Umbrella Filters "by MOBIN-UDDIN, et alii, published in N. Eng. Journ. Med. 286: 55-58, 1972. In a simplified manner, after compression in an appropriate conical receptacle, and fixing by screwing inside the umbrella, the filter is placed in a metallic cylindrical introduction capsule; the device is introduced into the venous system through the internal jugular vein of the exposed neck under local anesthesia. From this place, the device passes through successively the upper vena cava and the right atrium, to reach the lower vena cava. The device is then released; it opens naturally and its tips are inserted in the wall of the vein up to the level of the elastomer layer; in the inferior vena cava, the flow of blood is in such a direction (represented by the black arrow in fig. 1) that it can only open the umbrella filter even more and facilitate its attachment.

 However, if the umbrella name is perfectly justified, the MOBIN-UDDIN device only really fulfills its role as a filter for a relatively short period, generally from 1 month to 6 months depending on the case, because it closes quite quickly. It nevertheless makes it possible to promote the development of the collaterals in a very gradual manner, and because of its very effective attachment (in particular for the 28 mm model) does not have the drawback of migrating into the hearts of the patients.

 In the years 1968, appeared then a new technique known as the filter of KIMRAY-GREENFIELD, and which is widely described in an article entitled "Prevention of the pulmonary embolism thanks to the filter of KIMRAY-GREENFIELD" published in La Presse Médicale, 29 January 19B3, 12, n04, by F. LEMOIGNE et alii.

 This filter (21) described with reference to FIG. 2, is made up of metallic rays (22), linear, wavy or in broken lines, of rather great length, of the order of 50 mm, connected in their central part by a metal cap (23) and terminated at their second end by a harpoon (24). The ripples of the spokes are contained in a transverse plane, so that in the folded position, each spoke is articulated with the next.

 In such a filter is in particular more permeable than the previous umbrella filter of MOBIN-UDDIN, and has moreover been concluded for this purpose, but it has other drawbacks due to its method of attachment and its mode of introduction.

 In fact, by design, this filter is not occlusive and cannot be blocked. However, it is always situated in the direction of the blood flow (see arrow in FIG. 2), and must only be fixed to the venous wall 9 by the harpoons (24). It therefore has a certain tendency to largely perforate the vena cava. In addition, it may not open to the drop due to its mode of introduction. Indeed, in a manner somewhat analogous to the umbrella filter, it is placed in a metallic cylindrical capsule (25) for its introduction. But because of the large dimension of the rays, this capsule is more voluminous and the femoral approach is often prohibited, because of small caliber where certain venous endings are deformed and causes failure.

The jugular approach is therefore often preferred by the surgeon, but the positioning of the filter in its capsule is such that its opening is placed in the opposite direction to. blood flow and that without a regular intake of heparin there then forms in the capsule even a clot which prevents the opening of the filter. The length and flexibility of the whales means that they can intertwine; in addition, the metal introducer makes it impossible for the surgeon to visually check the condition of the filter inside.

 Finally, in a certain number of cases (around 12, according to the promoter of this technique), the filter is inclined, therefore poorly positioned, which causes less effective clot retention. This poor positioning is linked to a release of the filter from '' in an eccentric location and is clearly accentuated by the length of the whales and by the fact that the ancillary release device is not fixedly fixed.Moreover, the ancillary device for introducing and releasing the filter is different for each of these. two routes, which involves significant costs for each surgical intervention, especially when complications require changing lanes during the intervention, while in addition the regular supply of an anticoagulant requires a more complex device.

 The invention aims to produce a clot retention device of the type described in this preamble, but which combines the advantages of each, without having the disadvantages.

The device according to the present invention is remarkable in that the central core consists of a mass, of symmetrical shape, and in that the metal spokes are provided at their ends with spikes.

 In this way, the central core is perfectly symmetrical and the ancillary device for introduction and release is the same whatever the path chosen for its installation. In addition, the attachment by the tips and the arrangement of the filter in the direction of blood flow is very effective.

 According to a first variant of the invention, the central core consists of a silicone mass, covering the junction point of the metal spokes (or ribs).

 In this way, the material constituting the core is biologically acceptable, and prevents the formation of clots within the device itself at the node formed by the junction of the rays.

 According to a second variant of the invention, the central core can be spherical or ellipsoidal.

 According to a third variant of the invention, the spokes are wavy, in a longitudinal plane, so as to have a spring effect.

 The figures given in the appendix will make it possible to better understand how the invention continues and to better appreciate its scope.

 Figure 1 shows the MOBIN-UDDIN device and has been described previously.

 Figure 2 shows the KIMRAY-GREENFIELD device and has been described previously.

 FIG. 3 represents the new clot retention device according to the present invention, and will be described below.

 Finally, FIG. 4 represents the ancillary device for introducing and releasing the clot retention device, according to the present invention.

Referring to Figure 3, the device (31) consists of several spokes (32) which advantageously should be fixed at twelve, in order to optimize the retention capacity of the device compared to the different sizes of blood clots, which are led to migrate into the circulatory system, given the minimum size of the arteries that must be protected. Indeed, small blood clots are not very damaging to the human organism, especially for the main organs which do not retain or are not injured by clots of dimension less than 5 mm. At their junction, these spokes are embedded in a mass of symmetrical shape (33) that can preferably be chosen to be spherical or ellipsoidal - and possibly perforated at least partially according to a diameter and at its two ends. advantage that the ancillary device which allows the introduction of the filter into the human body and its release at the chosen location is identical whatever the jugular or femoral approach chosen. This ancillary device will be described later in detail. Finally, the spokes are provided at their ends with hooking means, preferably by spikes, which are connected to the spokes by a shoulder, in order to prevent them from injuring the wall of the support vein too deeply. the filter 31 being arranged in the direction of the blood flow, as indicated in FIG. 3 by the black arrow, it tends to open like the MOBIN filter
UDDIN, but, being not occlusive, the force tending to open is much less important.

 The ancillary introduction and release device is described with reference to FIG. 4. It comprises, in a manner almost similar to the prior devices, an introduction capsule (41), in the form of a cylinder of suitable dimensions. (for example, a length of 2 to 3 cm, and a diameter of 5 to 10 mm), in which is placed the filter device 31, which rests on a nacelle (42), and which will be ejected at the chosen location by a pusher (43). This capsule can be, according to the present invention and preferably, in a transparent material which thus allows the surgeon to visually control the positioning of the filter in the capsule, unlike the devices according to the prior art. which is moored the pusher (43) circulates freely inside a typically silicone sheath (44), under the action of a syringe type termination (45) that the surgeon or assistant can easily move in grabbing the handle (46) with his free fingers. Optionally, it can be provided at its distal end with a stylet (47) adapting to the perforated part of the filter olive and thus allowing better stability of the filter.

 According to a variant of the invention, the radii of the filter device (31) do not have the same length and can thus better adapt to the elliptical shape of the section of the inferior vena cava (the two diameters of which are approximately 26 mm and 30 mm).

In this case, the distal part of the capsule (41) is cut so that all the rays can be released simultaneously, at the ejection of the filter (elliptical quadric, with circular projection).

 According to another variant of the invention, the radii of the filter device (31) are wavy and these corrugations are contained in a longitudinal plane. The rays thus wavy offer the advantage of having a certain spring effect, and thus allow the filter device to absorb the variations in size of the vena cava linked to variations in pressure and cardiac hemodynamics. This effect does not exist in the previous devices, in particular of GREENFIEUD, and the authors frequently report perforations of the vein, which are obviously due to the movements of expansion and deflation of the vein, with impossibility for the filter to adapt.

 The spring effect is then accentuated by a different elasticity of the whales, depending on their position and their length, so as to allow a better adaptation of the filter to the walls of the vena cava, having regard to its variations in diameter.

 Finally, the handle (46) described above can also be modified so as to allow the adaptation of a syringe intended to introduce anticoagulants, such as heparin, during the introduction, to avoid the formation of 'a clot, and contrast media, to allow radiographic control of the location of the capsule during release. These contrast media can exit through one or more orifices made in the body of the pusher (43). It can also be provided with a ring (48) enabling the ancillary device to be fixedly positioned and thus to drop the filter exactly where intended. This ring does not exist in the prior art, so that small movements during ejection can cause variations in the actual position of the filter, compared to the desired position.

 The operating technique allowing the installation of the filter device (31) is relatively simple. In the case of a jugular approach, it requires prior cavography to identify the renal veins; the surgeon then makes a pre-sternocleidomastoid incision, under local anesthesia, so as to reach the internal jugular vein. The device having been placed in the capsule, the assembly is then lowered to the desired level, typically just below the renal veins; the release is then carried out under scopic control of the filter device, by action on the press-button. A radiological control with opacification is possible, so as to check that the filter device is correctly attached.

 In the case of a femoral approach, the surgeon makes an incision of the scarpa, under local anesthesia; the filter device being located in the reverse position in the capsule, it is necessary to introduce it by pushing by means of a complementary push-stylus (49), but in general, the ancillary device is identical.

Claims (8)

- CLAIMS 1.- Clot retention device, intended to be introduced into the circulatory system of a human being, and comprising a central core and a set of metal spokes, provided at their end with fixing means characterized in that the central core consists of a mass of symmetrical shape and in that the metal spokes are provided at their ends with spikes. 2.- Device according to claim 1, characterized in that the central core consists of a silicone mass, covering the junction point of the metal spokes. 3.- Device according to one of claims 1 or 2, characterized in that the central core is spherical or ellipsoidal.  4.- Device according to one of claims 1 or 2, characterized in that the metal spokes can be of different lengths. 5.- Device according to one of claims 1 to 4, characterized in that the central core is perforated, at least partially, according to a diameter. 6. Ancillary device for introducing and dropping a clot retention device according to one of claims 1 to 5, comprising an introduction capsule (41) and a pusher (45) connected by a tubular wire. disposed inside a sheath at said capsule, characterized in that the pusher is disposed at the end of a handle (46). 7.- Device according to claim 6, characterized in that the handle is provided with a ring (48). 8.- Device according to one of claims 6 or 7, characterized in that the introduction capsule is made of a transparent material.