Patent Description:
An embolization device is a permanent or semi-permanent implantable device that may be received within a bodily lumen so as to promote clot formation therein.

Embolization devices may be deployed in the vasculature at a particular location by a medical practitioner so as to promote blood clot formation and ultimately occlude the blood vessel. However, typical embolization devices may be prone to migration within the vasculature which may cause serious adverse effects.

To reduce migration, some known embolization devices, as disclosed for example in <CIT>, comprise a number of bristles or fibres extending radially outwardly from a central stem. The bristles are configured to contact the bodily lumen and anchor the embolization device in the lumen due to friction between the bristles and the wall of the lumen.

These embolization devices consist of a number of segments which are connected by a solid hypotube which is crimped to the distal end of a first segment and the proximal end of a second segment. This hypotube is made from a similar material to the stem wire but diameter and wall thickness render it much stiffer than the deformed wire in the stem.

When the embolization device is implanted into a bodily lumen of a patient, the embolization device may have to undergo significant bending to navigate the tortuous blood vessels of the patient's body. When a bending moment is induced in the in the stem of the embolization device, stress concentrations occur just outside the ends of the hypotube. In some cases, this may cause the stem wire to fracture at these locations. Once fracture occurs, the segments are no longer constrained and may be able to move relative to each other, increasing the risk of component migration, vessel perforation and, if the segment turns sideways, recanalization.

In view of the above, there is a need for an improved embolization device which can distribute the stress concentrations during bending more evenly and is therefore less prone to fracture. There is also a need for an improved method of assembling such an embolization device.

<CIT> discloses a bristle device for delivery into a body lumen comprises a longitudinally extending stem and a plurality of bristles extending generally outwardly from the stem for anchoring the device in a body lumen. There may be at least two bristle segments and in some cases there are flexible sections between the segments. The flexible sections articulate to enable the device to pass through a catheter placed in a tortuous anatomy or to be deployed in a curved vessel, or across a bifurcation. In some cases at least some of the bristle segments are spaced-apart to accommodate bending of the bristles.

<CIT> discloses a vascular treatment system and method including a plurality of self-expanding bulbs and a hypotube including interspersed patterns of longitudinally spaced rows of kerfs. Joints between woven structures and hypotubes include solder. Woven structures include patterns of radiopaque filaments measurable under x-ray. Structures are heat treated to include at least shapes at different temperatures. A catheter includes a hypotube including interspersed patterns of longitudinally spaced rows of kerfs. Heat treating systems include a detachable flange. Laser cutting systems include a fluid flow system.

To enable better understanding of the present disclosure, and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:.

In one aspect of the present invention, there is disclosed an embolization device for promoting clot formation in a bodily lumen and having a contracted delivery configuration and an expanded deployed configuration. The embolization device has a stem and a plurality of flexible bristles extending radially outwardly from the stem. The stem comprises a first wire element, a second wire element, and a tubular interconnect having a lumen and connecting the first wire element to the second wire element. The first wire element and the second wire element are disposed within the lumen of the tubular interconnect. The stem further comprises a reinforcing sleeve being fixedly disposed over at least part of the tubular interconnect and fixedly disposed over at least part of one or both of the first wire element and the second wire element. The reinforcing sleeve has a lower stiffness than the tubular interconnect.

In some embodiments this may result in an embolization device where the stress concentrations during bending are more evenly distributed and the embolization device may therefore be less prone to fracture.

Throughout this disclosure the term 'embolization device' may refer to a device which may be permanently or semi-permanently implanted in a bodily lumen. Accordingly, the 'embolisation device' may be configured to be disposed within the bodily lumen for a period of time, such as a number of days, or disposed in the lumen indefinitely. To this end, the 'embolisation device' may be configured to be selectively detached from a delivery element so that it may be implanted in the bodily lumen in isolation.

Throughout this disclosure the term 'bodily lumen' may refer to the inside space within a tubular structure of the human or animal body. The 'bodily lumen' may be, for example, an artery or vein.

Throughout this disclosure the term 'contracted delivery configuration' of an element may refer to a configuration of the element which has a smaller radial extent than an `expanded deployed configuration of the element.

Throughout this disclosure the term 'stiffness' of an element may refer to the extent to which the element resists deformation in response to an applied force. The stiffness may be an extensive property of the element and dependent upon the material and its shape and boundary conditions. The stiffness k of an element may be defined as k = F/d, where F is the force on the element and d is the displacement produced by the force along the same degree of freedom.

The reinforcing sleeve may be disposed over the entire length of the tubular interconnect.

The reinforcing sleeve may be fixed to the tubular interconnect and at least part of one or both of the first wire element and the second wire element by an interference fit.

In some embodiments this may result in a more even distribution of bending stresses resulting in an embolization device less prone to fracture.

The tubular interconnect may be made from a cobalt-chromium alloy.

In some embodiments this may result in a tubular interconnect with a high specific strength.

The reinforcing sleeve may be a polymer shrink tube, which has been shrunk in a radial direction to contact the tubular interconnect and the one or both of the first wire element and the second wire element.

In some embodiments this may result in easier assembly of the embolization device. In some embodiments, this may further result in a reinforcing sleeve with a tight interference fit.

The reinforcing sleeve may be radiopaque. The reinforcing sleeve may also be doped with a radiopaque material.

Throughout this disclosure, the term 'radiopaque' may refer to the property of a substance being opaque to X-Rays or similar radiation. Any radiopaque material/object referred to herein is radiopaque to such an extent that a practitioner may easily identify the material/object during fluoroscopy. In certain embodiment, any of the radiopaque materials/objects referred to herein have a radiodensity of at least <NUM> Hounsfield Units (HU), optionally at least <NUM> Hounsfield Units (HU), further optionally at least <NUM><NUM> Hounsfield Units (HU), even further optionally at least <NUM><NUM> Hounsfield Units (HU).

In some embodiments this may allow a physician to see the reinforcing sleeve under fluoroscopy, to aid the physician in placement of the embolization device inside a bodily lumen. In some embodiments this may alleviate the need for a separate radiopaque marker.

The tubular interconnect may comprise a radiopaque marker.

In some embodiments this may allow a physician to see the tubular interconnect under fluoroscopy, to aid the physician in placement of the embolization device inside a bodily lumen.

The tubular interconnect may be made from a radiopaque material.

The embolization device may further comprise a radiopaque marker element disposed proximate to the tubular interconnect.

The radiopaque marker element may be abutting the tubular interconnect.

The radiopaque marker element may be disposed about the first wire element and/or the second wire element.

The plurality of flexible bristles may be grouped into a first segment of flexible bristles and a second segment of flexible bristles.

In some embodiments this may result in easier handling of the embolization device. In some embodiments, this may further allow a modular design of the embolization device.

The first segment of bristles may extend radially outwardly from the first wire element. The second segment of bristles may extend radially outwardly from the second wire element.

The radiopaque marker element may be disposed about the second wire element abutting the tubular interconnect on one end and the second segment of flexible bristles on the other end.

In some embodiments this may allow a physician to identify the position of the tubular interconnect and the second segment of flexible bristles under fluoroscopy to aid in placement of the embolization device inside a bodily lumen.

The tubular interconnect may be crimped to the first wire element and/or the second wire element.

In some embodiments this may allow the first wire element to be securely connected to the second wire element.

The tubular interconnect may be attached to the first and/or the second wire element by an adhesive.

The reinforcing sleeve may be disposed over at least part of the tubular interconnect and at least part of the first wire element. The embolization device may further comprise another reinforcing sleeve disposed over at least part of the tubular interconnect and disposed over at least part of the second wire element.

In some embodiments this may result in easier assembly of the embolization device. In some embodiments, this may further result in an embolization device where the bending stress distribution at both ends of the tubular interconnect is more evenly distributed.

The another reinforcing sleeve may be identical to the reinforcing sleeve.

The another reinforcing sleeve may be disposed over at least part of the second wire element through an intermediate radiopaque marker element.

In another aspect of the present invention, there is provided a method of assembling an embolization device for promoting clot formation in a bodily lumen and having a contracted delivery configuration and an expanded deployed configuration. The embolization device has a stem and a plurality of flexible bristles extending radially outwardly from the stem. The stem comprises a first wire element and a second wire element. The method comprises connecting the first wire element and the second wire element using a tubular interconnect having a lumen, by disposing the first wire element and the second wire element inside the lumen of the tubular interconnect. The method further comprises fixedly disposing a reinforcing sleeve over at least part of the tubular interconnect and at least part of one or both of the first wire element and the second wire element. The reinforcing sleeve has a lower stiffness than the tubular interconnect.

In some embodiments this may allow for a method of assembling an embolization device where the bending stresses are distributed more evenly which may result in an embolization device less prone to fracture.

In some embodiments this may result in a modular design for the embolization device. In some embodiments this may further result in easier handling and disposal of the embolization device.

The first segment of bristles may extend radially outwardly from the first wire element and the second segment of bristles may extend radially outwardly from the second wire element.

The method may further comprise, prior to connecting the first wire element to the second wire element, disposing a radiopaque marker element about the first wire element and/or the second wire element.

In some embodiments this may result in the embolization device being visible under fluoroscopy. In some embodiments this may aid a physician in placing the embolization device in a bodily lumen.

After connecting the first and second wire element, the radiopaque marker element may be proximate to the tubular interconnect. The radiopaque marker element may be abutting the tubular interconnect.

In some embodiments this may result in a physician being able to identify the position of the tubular interconnect and the segments of flexible bristles under fluoroscopy.

The step of connecting a first wire element and a second wire element may further comprise crimping the tubular interconnect to the first wire element and/or the second wire element.

In some embodiments this may result in a secure connection between the first and second wire elements.

The step of connecting a first wire element and a second wire element may further comprise attaching the tubular interconnect to the first wire element and/or the second wire element using an adhesive.

The tubular sleeve may be radiopaque. The reinforcing sleeve has been doped with a radiopaque material.

In some embodiments this may allow the reinforcing sleeve to be seen under fluoroscopy, aiding in placement of the embolization device in a bodily lumen. In some embodiments this may alleviate the need for a separate radiopaque marker.

The method may further comprise axially compressing the reinforcing sleeve prior to connecting the first wire element and the second wire element.

In some embodiments this may allow the tubular interconnect to be crimped to the first wire element and the second wire element.

The method may further comprise straightening the reinforcing sleeve after connecting a first wire element and a second wire element.

In some embodiments this may allow the reinforcing sleeve to be disposed over the tubular interconnect.

After straightening the reinforcing sleeve, the reinforcing sleeve may be disposed over the entire length of the tubular interconnect.

The reinforcing sleeve may be a polymer shrink tube. Fixedly disposing the reinforcing sleeve may further comprise heating the reinforcing sleeve to shrink the reinforcing sleeve in a radial direction.

In some embodiments this may result in easier assembly of the embolization device. In some embodiments this may further result in a tight interference fit for the reinforcing sleeve.

After heating the reinforcing sleeve, the diameter of the reinforcing sleeve may be smaller than before heating.

After fixedly disposing the reinforcing sleeve, the reinforcing sleeve may contact the tubular interconnect and at least part of one or both of the first wire element and the second wire element, such that an interference fit is formed.

In some embodiments this may result in better and more even distribution of bending stresses along the stem of the embolization device.

The reinforcing sleeve may be fixedly disposed over at least part of the tubular interconnect and at least part of the first wire element and the method may further comprise fixedly disposing another reinforcing sleeve over at least part of the tubular interconnect and at least part of the second wire element.

In some embodiments this may result in easier assembly of the embolization device. In some embodiments, this may further result in an embolization device where the bending stress distributions at both ends of the tubular interconnect are more evenly distributed.

The method may further comprise axially compressing the reinforcing sleeve and the another reinforcing sleeve prior to connecting the first wire element and the second wire element.

The method may further comprise straightening the reinforcing sleeve and the another reinforcing sleeve after connecting a first wire element and a second wire element.

After straightening the reinforcing sleeve and the another reinforcing sleeve, the reinforcing sleeve may be disposed over part of the tubular interconnect and part of the first wire element. The another reinforcing sleeve may be disposed over part of the tubular interconnect and part of the second wire element.

The reinforcing sleeve and the another reinforcing sleeve may be polymer shrink tubes. Fixedly disposing the reinforcing sleeve and the another reinforcing sleeve may further comprise heating the reinforcing sleeve and the another reinforcing sleeve to shrink the reinforcing sleeve and the another reinforcing sleeve in a radial direction.

After heating the reinforcing sleeve and the another reinforcing sleeve, the diameter of the reinforcing sleeve and the another reinforcing sleeve may be smaller than before heating.

After fixedly disposing the reinforcing sleeve and the another reinforcing sleeve, the reinforcing sleeve may contact at least part of the tubular interconnect and at least part of the first wire element. The another reinforcing sleeve may contact at least part of the tubular interconnect and at least part of the second wire element, such that an interference fit is formed.

After fixedly disposing the reinforcing sleeve and the another reinforcing sleeve, the reinforcing sleeve may contact at least part of the tubular interconnect and at least part of the first wire element. The another reinforcing sleeve may contact at least part of the tubular interconnect, at least part of the radiopaque marker element and at least part of the second wire element, such that an interference fit is formed.

In a third aspect of the present disclosure there may be provided a kit comprising a first wire element having a first segment of a plurality of flexible bristles extending radially outwardly, a second wire element having a second segment of a plurality of bristles extending radially outwardly, a tubular interconnect and a reinforcing sleeve.

The kit may further comprise a radiopaque marker element.

<FIG> shows a side view of an embolisation device <NUM> for promoting blood clot formation in a bodily lumen according to the present disclosure. The embolization device <NUM> comprises a stem <NUM> and a plurality of flexible bristles <NUM> extending radially outwardly from the stem. The embolization device <NUM> has an expanded deployed configuration (not shown) where the flexible bristles <NUM> are biased against the inner wall of a bodily lumen to anchor the embolization device <NUM> in the bodily lumen and a contracted delivery configuration (not shown) where the radial extent of the flexible bristles <NUM> is reduced compared to the expanded deployed configuration so that the embolization device <NUM> can be disposed inside a catheter for delivery into, or retrieval from, the bodily lumen. When the embolization device <NUM> is disposed in the bodily lumen in the expanded deployed configuration, the flexible bristles <NUM> restrict the flow of blood through the bodily lumen causing an embolus of blood to form and grow to eventually occlude the bodily lumen. <FIG> shows the embolization device <NUM> in a relaxed state where the flexible bristles <NUM> are straight.

The stem <NUM> comprises a first wire element <NUM> and a second wire element <NUM>. The flexible bristles <NUM> are grouped into a first segment <NUM> which extends radially outwardly from the first wire element <NUM> and a second segment <NUM> extending radially outwardly from the second wire element <NUM>. The first wire element <NUM> and the second wire element <NUM> are twisted wires and can be made from Nitinol or cobalt-chromium, for example.

The first wire element <NUM> is connected to the second wire element <NUM> by a tubular interconnect <NUM>. The tubular interconnect <NUM> is a solid hypotube comprising a lumen which can be made from a similar material to the first and second wire elements, such as a cobalt-chromium alloy, for example. A distal end of the first wire element <NUM> and a proximal end of the second wire element <NUM> are disposed inside the lumen of the tubular interconnect <NUM> and the tubular interconnect <NUM> is crimped so as to connect the first wire element <NUM> to the second wire element <NUM>. Alternatively, a biocompatible adhesive may be used to connect the tubular interconnect <NUM> to the first and second wire elements <NUM>, <NUM>.

The embolization device <NUM> further comprises a second tubular interconnect <NUM> and a third tubular interconnect <NUM>. The second tubular interconnect <NUM> connects the second wire element <NUM> to an atraumatic distal end <NUM>. The atraumatic distal end <NUM> is designed so as to not perforate or cause damage to the internal wall of a bodily lumen. The third tubular interconnect <NUM> connects the proximal end of the first wire element <NUM> to a further wire element.

The embolization device <NUM> also comprises a radiopaque marker element <NUM> disposed around the second wire element <NUM> and abutting the tubular interconnect <NUM> on one end. The radiopaque marker may be made from any material which is radiopaque to the extent that it can be easily identified by a practitioner under fluoroscopy, such as a platinum iridium compound, for example.

Intravascular procedures such as the placement of embolization device <NUM> at a position within a bodily lumen of a patient are usually carried out under fluoroscopy which allows a physician to see the devices inside the bodily lumen. The radiopaque marker element <NUM> allows a physician to visually identify the position of the tubular interconnect, the first segment of bristles <NUM> and the second segment of bristles <NUM> under fluoroscopy. This will aid the physician in placing the embolization device <NUM> at the desired position in the bodily lumen of a patient.

Embolization device <NUM> further comprises a second radiopaque marker element <NUM> and a third radiopaque marker element <NUM>.

The second radiopaque marker element <NUM> allows the physician to visualise the distal end of the embolization device and the third radiopaque marker element <NUM> allows the physician to visualise of the position of the proximal end of the first wire element <NUM>.

The embolization device <NUM> further comprises a first reinforcing sleeve <NUM> and a second reinforcing sleeve <NUM>. The first reinforcing sleeve <NUM> is fixedly disposed over part of the tubular interconnect <NUM> and part of the first wire element <NUM>. The first reinforcing sleeve <NUM> is in contact with the tubular interconnect <NUM> and the first wire element <NUM> such that an interference fit is formed. Similarly, the second reinforcing sleeve <NUM> is disposed over part of the tubular interconnect <NUM>, the radiopaque marker element <NUM> and part of the second wire element <NUM>. The second reinforcing sleeve <NUM> is in contact with the tubular interconnect <NUM>, the radiopaque marker element <NUM> and the second wire element <NUM> such that an interference fit is formed.

The first reinforcing sleeve <NUM> is contacting the first segment <NUM> of flexible bristles <NUM> on one longitudinal end and the second reinforcing sleeve <NUM> on the other longitudinal end. The second reinforcing sleeve <NUM> is contacting the first reinforcing sleeve <NUM> at one longitudinal end and the second segment <NUM> of flexible bristles <NUM> on the other longitudinal end.

The first reinforcing sleeve <NUM> and the second reinforcing sleeve <NUM> are polymer shrink tubes which have been heated to reduce their diameter and produce an interference fit. The reinforcing sleeves may be made from a number of materials such as FEP, PTFE, Mylar or Polyolefin, for example. A method of how the reinforcing sleeves are disposed and the embolization device is assembled will be explained in more detail below with respect to <FIG> and <FIG>.

The first and second reinforcing sleeves <NUM>, <NUM> are disposed around the tubular interconnect <NUM> and at least part of the first wire element <NUM> and the second wire element <NUM>. This allows the bending stresses in the first and second wire elements <NUM>, <NUM> to be distributed more evenly, resulting in an embolization device which is less prone to fracture.

When placing the embolization <NUM> at the desired position inside the bodily lumen, the embolization device <NUM> disposed inside a catheter and is introduced into the body of a patient through an access site of the body. The embolization device <NUM> is then advanced into a distal direction and may need to undergo significant bending to navigate the tortuous blood vessels of the body to be placed at the desired position within the bodily lumen.

As noted above, the tubular interconnect <NUM> may be made from a similar material to the first and second wire elements <NUM>, <NUM>. However, due to the larger diameter of the tubular interconnect <NUM> and its wall thickness, the tubular interconnect <NUM> has a higher stiffness than the first and second wire elements.

When a bending moment is induced in the stem <NUM>, stress concentrations occur just outside the ends of the tubular interconnect <NUM>, due to the step change in stiffness from the tubular interconnect <NUM> to the wire elements. The first and second reinforcing sleeves <NUM>, <NUM> have a lower stiffness than the tubular interconnect <NUM> and cover the tubular interconnect <NUM> and part of the first and second wire elements <NUM>, <NUM>. The ratio of stiffnesses between the tubular interconnect <NUM> and the first and second wire elements <NUM>, <NUM> is reduced and the bending stresses are distributed more evenly along the first and second wire elements <NUM>, <NUM>. This will result in the stem <NUM> being less prone to fracture due to bending. The fatigue life of the embolization device <NUM> will be improved and even if fracture does occur, the first and second reinforcing sleeves <NUM>, <NUM> will help to prevent the first and second wire elements <NUM>, <NUM> moving relative to each other.

<FIG> and <FIG> illustrate a method of assembling the embolization device <NUM> of <FIG>.

<FIG> shows the embolization device <NUM> prior to fixedly disposing the first reinforcing sleeve <NUM> and the second reinforcing sleeve <NUM>.

When assembling the embolization <NUM>, the length of the embolization device <NUM> can be chosen according to the specific requirements of the patient. The required number of wire elements can then be connected to form the required length of the embolization device <NUM>.

In order to connect two wire elements such as the first wire element <NUM> and the second wire element <NUM>, the first reinforcing sleeve <NUM> is disposed over the first wire element <NUM> and axially compressed. The second reinforcing sleeve <NUM> is then disposed over the second wire element <NUM> and also axially compressed. <FIG> shows the axially compressed reinforcing sleeves <NUM>, <NUM>. A radiopaque marker element <NUM> may be disposed about the second wire element <NUM>. The distal end of the first wire element <NUM> and the proximal end of the second wire element <NUM> are then placed into opposite ends of the lumen of the tubular interconnect <NUM>.

Because the first and second reinforcing sleeves <NUM>, <NUM> are axially compressed, the tubular interconnect <NUM> is exposed. This allows a crimping tool to access the outer surface of the tubular interconnect <NUM> to crimp the tubular interconnect <NUM> to the first wire element <NUM> and the second wire element <NUM> and securely connect the first wire element <NUM> to the second wire element <NUM>.

<FIG> shows how after the tubular interconnect <NUM> is crimped to the first and second wire elements <NUM>, <NUM>, the first and second reinforcing sleeves <NUM>, <NUM> are straightened. The first reinforcing sleeve <NUM> is now disposed over part of the first wire element <NUM> and part of the tubular interconnect <NUM>, whereas the second interconnect is now disposed over part of the second wire element <NUM>, the radiopaque marker element <NUM> and part of the tubular interconnect <NUM>. At this stage the inner diameter of the reinforcing sleeves <NUM>, <NUM> is larger than the outer diameter of the tubular interconnect <NUM> and the first and second wire elements <NUM>, <NUM>.

In order to produce a tight interference fit between the reinforcing sleeves <NUM>, <NUM> and the tubular interconnect <NUM> and the first and second wire elements <NUM>, <NUM> the reinforcing sleeves <NUM>, <NUM> are heated. As the reinforcing sleeves <NUM>, <NUM> are polymer shrink tubes, by heating the reinforcing sleeves <NUM>, <NUM> above their crystalline melting point the radial diameter of the reinforcing sleeves <NUM>, <NUM> is reduced. This may be done, for example, by placing the embolization device <NUM> in an oven at the required temperature. In order to produce an interference fit, the inner diameter of the reinforcing sleeves <NUM>, <NUM> after heating must be smaller than the outer diameter of the tubular interconnect <NUM> and the first wire element <NUM> and the second wire element <NUM>.

After the reinforcing sleeves <NUM>, <NUM> are radially shrunk in diameter and produce an interference fit with the rest of the stem <NUM>, the embolization device <NUM> shown in <FIG> is produced.

Various modifications will be apparent to those skilled in the art. For example, the embolization device <NUM> may not comprise a radiopaque marker element <NUM>.

The tubular interconnect <NUM> may comprise a radiopaque marker element or the tubular interconnect <NUM> may itself be made of a radiopaque material.

The first and second reinforcing sleeves <NUM>, <NUM> may be doped with a radiopaque material to make the reinforcing sleeves <NUM>, <NUM> radiopaque. This could allow removal of the radiopaque marker element <NUM> and allow the tubular interconnect <NUM> to be made from a non-radiopaque material.

The radiopaque marker element <NUM> may be disposed proximate to but not abutting the tubular interconnect <NUM>.

The radiopaque marker element <NUM> may be disposed abutting the second segment <NUM> of flexible bristles <NUM>. In that case, the second reinforcing sleeve <NUM> will be disposed about tubular interconnect <NUM> and the radiopaque marker element <NUM> such that it is in contact with the tubular interconnect <NUM> and the radiopaque marker element <NUM>.

The first wire element <NUM> may also have a radiopaque marker disposed about it. This radiopaque marker may be identical to the radiopaque marker element <NUM>.

The flexible bristles <NUM> may not be grouped into segments but may be disposed uniformly along the length of the stem <NUM>.

The embolization device may be formed of any required number of wire elements connected together. Each wire element may comprise any number of segments of flexible bristles <NUM>.

The embolization device may not have an atraumatic distal end <NUM>.

The embolization device <NUM> may not have second and third radiopaque markers <NUM>, <NUM>. The embolization device <NUM> also may not have second and third tubular interconnects <NUM>, <NUM>.

The embolization device may only have one reinforcing sleeve. This reinforcing sleeve may be disposed over part of or the entire length of the tubular interconnect <NUM>. This reinforcing sleeve may be disposed over part of the first wire element <NUM> and/or the second wire element <NUM>.

The first and second reinforcing sleeves <NUM>, <NUM> may not be polymer shrink tubes. They may be elastic rubber sleeves, for example. Alternatively, they may be polymer sleeves which are deposited onto the stem <NUM> of the embolization device <NUM> as a coating.

One of the reinforcing sleeves may be shorter than the other reinforcing sleeve. The first reinforcing sleeve <NUM> and the second reinforcing sleeve <NUM> may not be in contact, leaving part of the tubular interconnect <NUM> exposed.

The first reinforcing sleeve <NUM> may not be contacting the first segment <NUM> of flexible bristles <NUM> at one longitudinal end.

The second reinforcing sleeve <NUM> may not be contacting second segment <NUM> of flexible bristles <NUM> at one longitudinal end.

The first wire element <NUM> and the second wire element <NUM> may not be made from a twisted wire stem. They may be made from a solid wire stem, for example.

All of the above are fully within the scope of the present disclosure, and are considered to form the basis for alternative embodiments in which one or more combinations of the above described features are applied, without limitation to the specific combination disclosed above.

Claim 1:
An embolization device (<NUM>) for promoting clot formation in a bodily lumen and having a contracted delivery configuration and an expanded deployed configuration, the embolization device (<NUM>) having a stem (<NUM>) and a plurality of flexible bristles (<NUM>) extending radially outwardly from the stem, the stem (<NUM>) comprising:
a first wire element (<NUM>);
a second wire element (<NUM>);
a tubular interconnect (<NUM>) having a lumen and connecting the first wire element (<NUM>) to the second wire element (<NUM>), the first wire element (<NUM>) and the second wire element (<NUM>) being disposed within the lumen of the tubular interconnect (<NUM>); and
a reinforcing sleeve (<NUM>, <NUM>) being fixedly disposed over at least part of the tubular interconnect (<NUM>) and fixedly disposed over at least part of one or both of the first wire element (<NUM>) and the second wire element (<NUM>),
characterized in that the reinforcing sleeve (<NUM>, <NUM>) has a lower stiffness than the tubular interconnect (<NUM>).