Patent Description:
An aneurysm is a dilation of a blood vessel that poses a risk to health from the potential for rupture, clotting, or dissecting. Rupture of an aneurysm in the brain causes stroke, and rupture of an aneurysm in the abdomen causes shock. Cerebral aneurysms are usually detected in patients as the result of a seizure or hemorrhage and can result in significant morbidity or mortality.

There are a variety of materials and devices which have been used for treatment of aneurysms, including platinum and stainless steel microcoils, polyvinyl alcohol sponges (Ivalone), and other mechanical devices. For example, vaso-occlusion devices are surgical implements or implants that are placed within the vasculature of the human body, typically via a catheter, either to block the flow of blood through a vessel making up that portion of the vasculature through the formation of an embolus, or to form such an embolus within an aneurysm stemming from the vessel.

Sometimes, when a vaso-occlusion device is being carried within the catheter, the vaso-occlusion device is elastically bent to conform with a profile of the catheter. This elastic bending of the vaso-occlusion device creates various pressure points against the inner surface of the catheter, which may be undesirable because it makes advancement of the vaso-occlusion device relative to the catheter harder. In some cases, increased axial force may need to be exerted in order to push the vaso-occlusion device distally. This increased axial force may sometimes cause premature buckling of the vaso-occlusion device inside the catheter.

Also, a vaso-occlusion device may assume a certain three-dimensional shape after it is deployed outside the catheter. If the deployed vaso-occlusion device is too stiff, it may not conform with a shape of the body cavity intended to be occluded by the vaso-occlusion device. On the other hand, if the deployed vaso-occlusion device is too flexible, then the vaso-occlusion device may not retain its shape, and may be unintentionally bent into an undesirable shape, rendering it incapable of occluding the body cavity.

<CIT> discloses an adjustable embolic aneurysm coil. The device can be adjusted within the body of a patient in a minimally invasive or non-invasive manner such as by applying energy percutaneously or external to the patient's body. The energy may include, for example, acoustic energy, radio frequency energy, light energy and magnetic energy. Thus, the size and/or shape of the embolic coil can be adjusted to provide optimal filling of the aneurysm. In certain embodiments, the devices include a shape memory material that is responsive to changes in temperature and/or exposure to a magnetic field. A material having enhanced absorption characteristics with regard to a desired heating energy may be used in order to facilitate heating and adjustment of the embolic coil.

The invention is based on the task of providing an improved medical device of the type described above. The invention is set out in claims.

In accordance with the invention is an embolic device provided in claim <NUM>.

As an example, that may, if applicable, provide details to further specify embodiments claimed or described in this application an embolic device for placement in a body lumen is provided that includes: an elongated member having a linear configuration when in room temperature, the elongated member being configured to form a first three-dimensional structure in response to body temperature; wherein the elongated member comprises a first segment, a second segment, and a third segment, the second segment being located between the first segment and the third segment; wherein the first segment and the third segment are configured to change their respective shapes in response to the body temperature; and wherein the second segment that is located between the first segment and the third segment has a shape that is independent of the body temperature.

Optionally, the first segment is configured to form a first portion of a loop, and the third segment is configured to form a second portion of the loop in response to the body temperature.

Optionally, the first segment is configured to form a first loop, and the third segment is configured to form a second loop, in response to the body temperature.

Optionally, the first segment has a first length, the second segment has a second length, and the third segment has a third length; and wherein the second length of the second segment is shorter than the first length of the first segment, and is also shorter than the third length of the third segment.

Optionally, the second length of the second segment that is between the first segment and the third segment is less than <NUM>% of the first length of the first segment, and is also less than <NUM>% of the third length of the third segment.

Optionally, the elongated member has a distal end and a proximal end opposite from the distal end, and wherein the embolic device further comprises a fourth segment that includes the proximal end; and wherein the fourth segment is martensitic when the fourth segment is in the room temperature, and is also martensitic when the fourth segment is in the body temperature.

Optionally, the first segment is martensitic when the first segment is in the room temperature, and is austenitic when the first segment is in the body temperature.

Optionally, the second segment is martensitic when the second segment is the room temperature, and is martensitic when the second segment is in the body temperature.

Optionally, the three-dimensional structure comprises a plurality of loops, and wherein the first segment, the second segment, and the third segment comprise respective portions of one of the loops.

Optionally, the elongated member further comprises a fourth segment, a fifth segment, and a sixth segment that comprise respective portions of another one of the loops; wherein the fifth segment is between the fourth segment and the sixth segment; wherein the fourth segment and the sixth segment are configured to change their respective shapes in response to the body temperature; and wherein the fifth segment that is located between the fourth segment and the sixth segment has a shape that is independent of the body temperature.

As a further example, that may, if applicable, provide details to further specify embodiments claimed or described in this application an embolic device for placement in a body lumen is provided that includes: an elongated member having a linear configuration when in room temperature, the elongated member being configured to form a first three-dimensional structure in response to body temperature; wherein the elongated member comprises a first segment, a second segment, and a third segment, the second segment being located between the first segment and the third segment; wherein the first segment is martensitic when the first segment is in the room temperature, and is austenitic when the first segment is in the body temperature; and wherein the second segment is martensitic when the second segment is in the room temperature, and is also martensitic when the second segment is in the body temperature.

Optionally, the first segment is configured to form a first portion of a loop, and the third segment is configured to form a second portion of the loop, in response to the body temperature.

Optionally, the elongated member has a distal end and a proximal end opposite from the distal end, and wherein the embolic device further comprises a fourth segment that includes the proximal end; and wherein the fourth segment is martensitic when in the room temperature, and is also martensitic when the fourth segment is the body temperature.

Optionally, the elongated member further comprises a fourth segment, a fifth segment, and a sixth segment that comprise respective portions of another one of the loops; wherein the fifth segment is between the fourth segment and the sixth segment; wherein the fourth segment and the sixth segment are martensitic when the fourth segment and the sixth segment are in the room temperature, and are austenitic when the fourth segment and the sixth segment are in the body temperature; and wherein the fifth segment is martensitic when the fifth segment is in the room temperature, and is also martensitic when the fifth segment is in the body temperature.

As a mere example how an embolic device according to the invention may be utilized, a method is provided of occluding a body lumen performed by an embolic device having an elongated member, the elongated member comprising a first segment, a second segment, and a third segment, wherein the second segment is between the first segment and the third segment, includes: undergoing a first shape change by the first segment of the elongated member in response to body temperature; undergoing a second shape change by the second segment of the elongated member in response to force; and undergoing a third shape change by the third segment of the elongated member in response to the body temperature.

Optionally, the first segment is martensitic when the first segment is in the room temperature, and is austenitic when the first segment is in the body temperature; and wherein the second segment is martensitic when the second segment is in the room temperature, and is also martensitic when the second segment is in the body temperature.

Optionally, the first segment forms a first portion of a loop, and the third segment forms a second portion of the loop, in response to the body temperature.

Optionally, the first segment forms a first loop, and the third segment forms a second loop, in response to the body temperature.

Other and further aspects and features will be evident from reading the following detailed description.

The drawings illustrate the design and utility of embodiments, in which similar elements are referred to by common reference numerals. These drawings are not necessarily drawn to scale. In order to better appreciate how the above-recited and other advantages and objects are obtained, a more particular description of the embodiments will be rendered, which are illustrated in the accompanying drawings. These drawings depict only exemplary embodiments and are not therefore to be considered limiting in the scope of the claims.

It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are represented by the same reference numerals throughout the figures.

<FIG> illustrates a medical device <NUM> having a catheter <NUM> for delivering an embolic device <NUM> in a body lumen. The catheter <NUM> has a distal end <NUM>, a proximal end <NUM>, and a catheter body <NUM> extending between the distal end <NUM> and the proximal end <NUM>. The embolic device <NUM> is contained within a lumen <NUM> of the catheter <NUM>. The medical device <NUM> further includes a shaft <NUM> located in the lumen <NUM> for pushing the embolic device <NUM> out of the lumen <NUM> of the catheter <NUM>.

As shown in <FIG>, the embolic device <NUM> is made from an elongated member <NUM> having a distal end <NUM>, a proximal end <NUM>, and a body <NUM> extending between the distal end <NUM> and the proximal end <NUM>. The elongated member <NUM> of the embolic device <NUM> has a linear configuration (e.g., a straight profile) when being in room temperature inside the catheter <NUM>. The elongated member <NUM> is configured to form a three-dimensional structure <NUM> in response to body temperature when the elongated member <NUM> is delivered outside the catheter <NUM> into a patient's body (<FIG>).

<FIG> illustrates an example of the embolic device <NUM>. As shown in the figure, the elongated member <NUM> of the embolic device <NUM> has a linear configuration that is relatively straight when in room temperature. The elongated member <NUM> is configured to form the three-dimensional structure in response to body temperature. The straight profile of the elongated member <NUM> in the catheter <NUM> is thus mainly due to the elongated member <NUM> being in room temperature, and it is not mainly due to any mechanical straightening caused by the catheter <NUM>. This feature is advantageous because it reduces friction between the elongated member <NUM> and the inner wall of the catheter <NUM> so that the embolic device <NUM> can be easier advanced distally. This feature also allows a longer embolic device <NUM> to be delivered if needed.

In the illustrated embodiments, the elongated member <NUM> has a first segment <NUM>, a second segment <NUM>, and a third segment <NUM>. The second segment <NUM> is located between the first segment <NUM> and the third segment <NUM>. The first segment <NUM> and the third segment <NUM> are configured to change their respective shapes in response to the body temperature. The second segment <NUM> that is located between the first segment <NUM> and the third segment <NUM> has a shape that is independent of the body temperature.

It should be noted that the term "body temperature", as used in this specification, may refer to a range of temperature, such as a temperature range of 95F to 107F, or more preferably a temperature range of 96F to 100F, or more preferably a temperature range of 97F to 99F. Also, as used in this specification, the term "room temperature" may refer to any temperature that is different from the body temperature. For example, room temperature may be any temperature that is lower than body temperature. In some embodiments, the room temperature may be any temperature that is at least 10F below the body temperature, or that is at least 20F below the body temperature.

In the illustrated embodiments, the first segment <NUM> is martensitic when the first segment <NUM> is in the room temperature, and is austenitic when the first segment <NUM> is in the body temperature. The second segment <NUM> is martensitic when the second segment <NUM> is the room temperature, and is martensitic when the second segment <NUM> is in the body temperature. The third segment <NUM> is martensitic when the third segment <NUM> is in the room temperature, and is austenitic when the third segment <NUM> is in the body temperature. Accordingly, the first and third segments <NUM>, <NUM> are reversible Martensite segments that allow the first and third segments <NUM>, <NUM> to have a relatively straight profile when in room temperature, and that allow the first and third segments <NUM>, <NUM> to change to Austenite segments in response to body temperature. On the other hand, the second segment <NUM> is an irreversible Martensite segment that allows the second segment <NUM> to have a relatively straight profile when in both room temperature and body temperature.

In the illustrated embodiments, the second segment <NUM> is softer than the first segment <NUM> and the third segment <NUM>. This allows the second segment <NUM> to more easily bend in response to force compared to the first and third segments <NUM>, <NUM>.

It should be noted that as used in this specification, the term "straight" may be used to describe a delivery shape of the embolic device <NUM> that is rectilinear or curvilinear, as long as the delivery shape has a curvature that is smaller than a curvature of the embolic device <NUM> in its deployed shape.

As shown in <FIG>, the elongated member <NUM> is configured to form the three-dimensional structure <NUM> that comprises a plurality of loops <NUM> in response to body temperature after the elongated member <NUM> is deployed. As shown in the figure, the first segment <NUM>, the second segment <NUM>, and the third segment <NUM> are parts of one of the loops <NUM>. Thus, the first segment <NUM> is configured to form a first part of a loop <NUM>, and the third segment <NUM> is configured to form a second part of the same loop <NUM> in response to the body temperature.

As shown in the figure, the elongated member <NUM> further comprises a fourth segment <NUM>, a fifth segment <NUM>, and a sixth segment <NUM> that are parts of another one of the loops <NUM>. The fifth segment <NUM> is between the fourth segment <NUM> and the sixth segment <NUM>. The fourth segment <NUM> and the sixth segment <NUM> are configured to change their respective shapes in response to the body temperature. The fifth segment <NUM> that is located between the fourth segment <NUM> and the sixth segment <NUM> has a shape that is independent of the body temperature. In some embodiments, the fourth segment <NUM> and the sixth segment <NUM> are martensitic when the fourth segment <NUM> and the sixth segment <NUM> are in the room temperature, and are austenitic when the fourth segment <NUM> and the sixth segment <NUM> are in the body temperature; and wherein the fifth segment <NUM> is martensitic when the fifth segment <NUM> is in the room temperature, and is also martensitic when the fifth segment <NUM> is in the body temperature.

In some embodiments, the elongated member <NUM> may include multiple sets of three segments, with each set of the three segments being configured to form a loop (or other desired curvilinear shape) for the three-dimensional structure <NUM>. In each set of the three segments, the first and the last segments are configured to change shape in response to body temperature, and the second segment that is between the first and the third segments has a shape that is independent of the body temperature. Thus, when the elongated member <NUM> is delivered from outside the patient to inside the patient, the elongated member <NUM> is subjected to a change in temperature from room temperature to body temperature. As a result, the first and third segments in each of the sets of the elongated member <NUM> will change their shapes in response to the body temperature, and the second segments in the sets of the elongated member <NUM> will not respond to the body temperature and will not changing their shapes due to the body temperature.

In some embodiments, the first segment <NUM> has a first length, the second segment <NUM> has a second length, and the third segment <NUM> has a third length. The second length of the second segment <NUM> is shorter than the first length of the first segment <NUM>, and is also shorter than the third length of the third segment <NUM>. For example, the second length of the second segment <NUM> that is between the first segment <NUM> and the third segment <NUM> may be less than <NUM>% of the first length of the first segment, and is also less than <NUM>% of the third length of the third segment.

In the above embodiments, the second segment <NUM> is described as being between the first segment <NUM> and the third segment <NUM>, wherein all three segments <NUM>, <NUM>, <NUM> are parts of a loop. In other embodiments, the second segment <NUM> may be located at other positions. For example, in other embodiments, the second segment <NUM> may be located closer to one end of a loop. In such cases, the respective lengths of the first and third segments <NUM>, <NUM> may be different from each other. As another example, in other embodiments, the second segment <NUM> may be located between two loops. In such cases, the first segment <NUM> is configured to form a first loop, and the third segment <NUM> is configured to form a second loop, in response to the body temperature. The second segment <NUM> located between the two loops (formed by the first and third segments <NUM>, <NUM>) does not change shape in response to the body temperature. Instead, the second segment <NUM> may be configured to change shape in response to force. In some cases, the second segment <NUM> may be located at an inflection point between two loops.

Also, in other embodiments, instead of having only one irreversible Martensite segment (e.g., segment <NUM>) for each loop <NUM>, the embolic device <NUM> may have multiple irreversible Martensite segments for each loop <NUM>.

In one or more embodiments described herein, the embolic device <NUM> may optionally further include a segment at its proximal end. <FIG> illustrates another example of the embolic device <NUM>. The embolic device <NUM> is similar to the embolic device <NUM> described with reference to <FIG>, except that the embolic device <NUM> further includes a segment <NUM> at its proximal end. As shown in <FIG>, the embolic device <NUM> includes the first, second, and third segments <NUM>, <NUM>, <NUM> as similarly described. However, the embolic device <NUM> further includes a fourth segment <NUM> at the proximal end of the elongated member <NUM>. The fourth segment <NUM> does not change shape in response to body temperature. As shown in <FIG>, after the embolic device <NUM> is subjected to body temperature, a majority of the length of the elongated member <NUM> changes shape to form the three-dimensional structure <NUM>. However, the fourth segment <NUM> remains straight and does not change its shape. Instead, the fourth segment <NUM> is configured to change shape in response to force. For example, when the embolic device <NUM> with the fourth segment <NUM> is delivered into an aneurysm, the interior wall of the aneurysm, or other parts of the embolic device <NUM> that have already been delivered inside the aneurysm, may exert a force on the fourth segment <NUM> when the fourth segment <NUM> is pushed out of the catheter <NUM>. This will cause the fourth segment <NUM> to bend. In some embodiments, the fourth segment <NUM> is martensitic when the fourth segment is in the room temperature, and is also martensitic when the fourth segment <NUM> is in the body temperature. Also, in some embodiments, the fourth segment <NUM> is softer than a segment with shape-memory characteristic (e.g., first segment <NUM>, third segment <NUM>, etc.). Accordingly, the fourth segment <NUM> can bend easier when an external force is applied. This allows the fourth segment <NUM> to be formed into any shape, depending on a direction and magnitude of the external force. In some cases, the fourth segment <NUM> may be configured for filling purpose to fill a space inside a body cavity, such as an aneurysm. In some embodiments, the fourth segment <NUM> may have a length that is greater than a length of a preceding loop <NUM>. For example, the fourth segment <NUM> may have a length that is equal to 1X, 2X, 3X or 4X the length of the segment forming a preceding loop <NUM>.

In some embodiments, the fourth segment <NUM> may be made from the same material as that for segment <NUM>, and may have the same mechanical property as that of segment <NUM>. In other embodiments, the fourth segment <NUM> may be softer than the segment <NUM>.

In the illustrated embodiments, the loops <NUM> of the three-dimensional structure <NUM> are connected by respective inflection points, which allow adjacent loops <NUM> to form reverse curvatures. In other embodiments, adjacent loops <NUM> of the three-dimensional structure <NUM> may not form reverse curvatures. Furthermore, in other embodiments, instead of loops, the first three-dimensional structure <NUM> may have other structural elements with shapes that are not loops.

In some embodiments, the curvatures of the loops <NUM> of the three-dimensional structure <NUM> may be the same. In other embodiments, one or more of the loops <NUM> may be different from another one of the loops <NUM> in the three-dimensional structure <NUM>. For example, in some embodiments, the three-dimensional structure <NUM> may have a first loop <NUM> with a first curvature, and a second loop <NUM> proximal to the first loop <NUM>, wherein the second loop <NUM> may have a second curvature that is higher than the first curvature of the first loop <NUM>. In other embodiments, the three-dimensional structure <NUM> may have a first loop <NUM> with a first curvature, and a second loop <NUM> proximal to the first loop <NUM>, wherein the second loop <NUM> may have a second curvature that is lower than the first curvature of the first loop <NUM>. As used in this specification, "curvature" may be defined as <NUM>/R, where R may be the smallest radius of curvature associated with the curve.

In some embodiments, the three-dimensional structure <NUM> has at least two loops <NUM> (e.g., at least two adjacent loops <NUM>) with respective loop dimensions that do not vary by more than <NUM>%, and preferably that do not vary by more than <NUM>%. For example, in one implementation, the three-dimensional structure <NUM> may have loops <NUM> with the same loop dimension (e.g., loop width or diameter). In other embodiments, the three-dimensional structure <NUM> may have loops <NUM> with respective loop dimensions that vary by more than <NUM>%.

In addition, in some embodiments, the loops <NUM> in the three-dimensional structure <NUM> have respective loop dimensions that reduce along the length of the elongated member <NUM> from the distal-to-proximal direction. This feature is advantageous because it assists the elongated member <NUM> in forming different filling structures that are smaller than the previous ones, thereby allowing the subsequent filling structures to fit within the previous ones.

In some embodiments, a first portion of the embolic device <NUM> may have a first width, and a second portion of the embolic device <NUM> that is proximal to the first portion may have a second width that is less than the first width. Alternatively or additionally, the first portion of the embolic device <NUM> may have a first thickness, and the second portion of the embolic device <NUM> may have a second thickness that is less than the first thickness. In one implementation, the elongated member <NUM> may be a braided structure, and the narrower width and/or thickness of the second portion of the embolic device <NUM> may be accomplished by using fewer strands of fiber to form the braid for the second portion compared to the number of strands of fiber used to form the braid for the first portion. Alternatively, the narrower width (or thickness) of the second portion of the embolic device <NUM> may be accomplished by cutting or grinding away (e.g., using laser cutter, grinder, etc.) some of the member that is used to form the second portion. As another alternative, the first and second portions of the embolic device <NUM> may be formed from separate members with different respective cross-sectional dimensions. In such cases, the members may be secured to each other, e.g., using adhesive, weld, fusion, mechanical coupler, etc. It should be noted that the terms "width" and "thickness" may refer to the longer and shorter dimensions of a cross section in some cases, such as cross section having a rectangular shape or an elliptical shape. However, use of either of these terms should not imply that the cross section has an elongated shape. For example, width or thickness of a cross section may refer to a cross sectional dimension of a circular cross section, a square cross section, a hexagon cross section, a pentagon cross section, etc..

Also, in some embodiments, the angles (between adjacent loops <NUM>) of the three-dimensional structure <NUM> may progressively reduce in the distal-to-proximal direction along the length of the elongated member <NUM>. This feature is advantageous because it may allow a distal portion of the elongated member <NUM> to form a first part of a three-dimensional structure <NUM> that is along a perimeter of a body cavity, and also may allow a proximal portion of the elongated member <NUM> to form a second part of the three-dimensional structure <NUM> that can fit within the first part of the three-dimensional structure <NUM>. In one implementation, a first portion of the elongated member <NUM> may be configured to form a first plurality of loops <NUM> with a first plurality of angles between adjacent ones of the first plurality of loops <NUM>, and a second portion of the elongated member <NUM> may be configured to form a second plurality of loops <NUM> with a second plurality of angles between adjacent ones of the second plurality of loops <NUM>. The first plurality of angles may be the same as each other, and the second plurality of angles may be the same as each other. However, the first plurality of angles may be larger than the second plurality of angles.

As discussed, in some embodiments, the elongated member <NUM> may have progressively reducing angles between adjacent loops from distal end to proximal end of the elongated member <NUM>. This allows the elongated member <NUM> to fill a body cavity from "outside-towards-inside" so that an outer space within the body cavity is filled first before the inner space in the aneurysm. In other embodiments, the elongated member <NUM> may have progressively increasing angles between adjacent loops from distal end to proximal end of the elongated member <NUM>. This allows the elongated member <NUM> to fill the body cavity from "inside-towards-outside" so that an inner space within the body cavity is filled first before the outer space in the body cavity.

In some embodiments, the elongated member <NUM> of the embolic device <NUM> may be a braided structure. In one implementation, the elongated member <NUM> may be formed by twenty-four strands of fibers that are braided. Alternatively, other numbers of strands of fibers may be used to form the elongated member. Also, in some embodiments, a proximal portion of the elongated member <NUM> may be formed using more strands compared to a distal portion of the elongated member <NUM>. In other embodiments, the distal portion of the elongated member <NUM> may be formed using more strands compared to the proximal portion of the elongated member <NUM>, thereby making the distal portion stiffer compared to the proximal portion.

In other embodiments, the elongated member <NUM> of the embolic device <NUM> may be a coil. In such cases, the elongated member <NUM> has a primary shape that is a coil, and the coil may then be bent to form a desired secondary shape (deployed shape).

In further embodiments, the elongated member <NUM> of the embolic device <NUM> may be a solid continuous member. In such cases, the solid continuous member has a primary shape that is straight, and the solid continuous member may then be bent to form a desired secondary shape (deployed shape).

In one or more embodiments described herein, the length of the elongated member <NUM> of the embolic device <NUM> may be anywhere from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM>. In other embodiments, the length of the elongated member <NUM> of the embolic device <NUM> may be less than <NUM> or more than <NUM>.

Also, in one or more embodiments described herein, the elongated member <NUM> of the embolic device <NUM> may be made from any suitable materials. By means of non-limiting examples, the elongated member <NUM> of the embolic device <NUM> may be made from Nitinol®, AuPt, stainless steel, platinum, other metals, other alloys, or any combination of the foregoing.

In some embodiments, each previous portion of the elongated member <NUM> forms a filling structure that allows accommodation of later portion(s) of the elongated member <NUM>. This allows different layers of structures to be progressively delivered into the aneurysm in a nesting configuration to fill the aneurysm from the periphery towards the center of the aneurysm. In some embodiments, a first portion of the elongated member <NUM> may have a first set of loops, a second portion of the elongated member <NUM> proximal to the first portion may have a second set of loops, a third portion of the elongated member <NUM> proximal to the second portion may have a third set of loops, etc. The first set of loops may have loop widths that are the same in size, or that decrease in size in the distal-to-proximal direction. Similarly, the second set of loops may have loop widths that are the same in size, or that decrease in size in the distal-to-proximal direction. Also, the third set of loops may have loop widths that are the same in size, or that decrease in size in the distal-to-proximal direction. In addition, in some embodiments, the first (i.e., distal) loop in a subsequent portion of the elongated member <NUM> may have a width that is smaller than a width of the last (i.e., proximal) loop in a previous portion of the elongated member <NUM>. Alternatively, in other embodiments, the first (i.e., distal) loop in a subsequent portion of the elongated member <NUM> may have a width that is larger than a width of the last (i.e., proximal) loop in a previous portion of the elongated member <NUM>.

In one or more embodiments described herein, the embolic device <NUM> may optionally further include a distal loop at the distal end of the embolic device <NUM>, wherein the distal loop has a diameter that is <NUM>% of less of the diameter of the loop proximal to the distal loop. As used in this specification, a "diameter" of a loop does not necessarily imply that the loop has a circular shape, and the term "diameter" may refer to a width of a loop, which may or may not be circular in shape. For example, a diameter of a loop may refer to a largest width of the loop in some cases.

Also, in one or more embodiments described herein, the embolic device <NUM> may optionally further include a distal coil at the distal end of the embolic device <NUM>. In one implementation, if the elongated member <NUM> of the embolic device <NUM> is formed from a braid, the distal coil may be formed from one or more strands of the braid. In another implementation, a separate coil may be provided as the distal coil, and is then attached to the distal end of the elongated member <NUM>.

In addition, in one or more embodiments described herein, the embolic device <NUM> may optionally further include a proximal coil at the proximal end of the embolic device <NUM>. In one implementation, if the elongated member <NUM> of the embolic device <NUM> is formed from a braid, the proximal coil may be formed from one or more strands of the braid. In another implementation, a separate coil may be provided as the proximal coil, and is then attached to the proximal end of the elongated member <NUM>. The proximal coil is advantageous because it may provide stiffness transition from the embolic device <NUM> to the shaft <NUM>.

Also, in one or more embodiments described herein, a proximal portion of the embolic device <NUM> may have a stiffness (e.g., bending stiffness and/or axial stiffness) that is different from a stiffness (e.g., bending stiffness and/or axial stiffness) of a distal portion of the embolic device <NUM>. In some embodiments, the proximal portion of the embolic device <NUM> may have a column strength that is different from a column strength of the distal portion. For example, the column strength of the proximal portion of the embolic device <NUM> may be higher than a column strength of the proximal portion of the embolic device <NUM>. This is advantageous because it allows the embolic device <NUM> to be pushed distally inside the catheter <NUM> without buckling. The relative difference in column strength and/or stiffness may be achieved using metallurgical heat treat condition, by variation in the cross-sectional dimension, and/or by varying number of strands in a braided structure, along the length of the elongated member <NUM>.

Also, in one or more embodiments described herein, if the elongated member <NUM> is a braided structure, the braid angle of the strands along the length of the member <NUM> may be varied in order to change the stiffness along the length of the elongated member <NUM>. For example, in some embodiments, a proximal portion of the elongated member <NUM> and a distal portion of the elongated member <NUM> may have the same number of strands, but the braid angle (e.g., angle formed by the strands with respect to the longitudinal axis of the member <NUM>) of the strands in the proximal portion may be larger than the braid angle of the strands in the distal portion, thereby making the proximal portion of the elongated member <NUM> stiffer than the distal portion of the elongated member <NUM>. In other embodiments, the braid angle of the strands in the distal portion of the elongated member <NUM> may be larger than the braid angle of the strands in the proximal portion of the elongated member <NUM>, thereby making the second portion of the elongated member <NUM> softer than the first portion of the elongated member <NUM>. Also, in some embodiments, the braid angle of the strands along the length of the member <NUM> may vary gradually.

In addition, in some embodiments, the three-dimensional structure comprises a first plurality of loops <NUM>, and wherein loop widths, loop curvatures, braid widths, braid angles, or any combination of the foregoing, of the respective ones of the first plurality of loops <NUM> increase or decrease along a length of the elongated member <NUM> forming the three-dimensional structure <NUM>.

In addition, in some embodiments, the three-dimensional structure <NUM> comprises a plurality of loops <NUM>, and wherein angles between adjacent ones of the plurality of loops <NUM> increase or decrease along a length of the elongated member <NUM> forming the three-dimensional structure <NUM>.

Furthermore, it should be noted that the embolic device <NUM> is not limited to the examples described herein, and that the embolic device <NUM> may have other configurations in other embodiments. For example, in other embodiments, the embolic device <NUM> may be configured to form other three-dimensional structures that are different from the ones described herein.

In further embodiments, the embolic device <NUM> is not configured to fill a body cavity from the periphery of the body cavity towards the center, nor is it configured to fill the body cavity from the center towards the periphery of the body cavity. Instead, the embolic device may be configured to fill the body cavity from one side of the body cavity towards an opposite side. Alternatively, the embolic device may be configured to fill the body cavity in a random manner.

Various techniques may be used to form the embolic device <NUM>. In some embodiments, the elongated member <NUM> may be wrapped around one or more mandrels to form a desired shape. The mandrel(s) may include multiple posts configured to allow the elongated member <NUM> to wrap there-around. The sizes of the posts will dictate the loop sizes of the loops to be formed. Also, the relative orientation of the posts will dictate the relative angles among the loops to be formed. After the elongated member <NUM> has been wrapped around the mandrel(s), the elongated member <NUM> may be chemically treated and/or heat treated to achieve the deployed shape of the elongated member <NUM>, and/or to provide different mechanical properties for different portions of the elongated member <NUM>.

In some embodiments, controlled heating and/or local heating may be performed so that the different segments along the length of the elongated member <NUM> will have different phase transition temperatures. This can be done for example by laser heating. In particular, a first heat treatment condition may be applied to a first set of segments (e.g., segment <NUM>, <NUM>, etc.) along the length of the elongated member <NUM>, so that their transformation temperature is higher than body temperature (37C). Accordingly, these segments will retain their Martensite phase when the device is deployed into a treatment site. They are therefore considered to be irreversible Martensite segments since there is no phase transformation of Martensite into Austenite. In contrast, a second heat treatment condition may be applied to a second set of segments (e.g., segments <NUM>, <NUM>, <NUM>, <NUM>, etc.), so that their transformation temperature is lower than body temperature (37C). These segments will have a phase transformation from Martensite to Austenite when the embolic device <NUM> is deployed into the treatment site. They are considered to be reversible Martensite segments. In general, thermal induced Martensite occurs as twinned Martensite, and the twinned Martensite structures can turn into detwinned structures by deforming the material in the martensitic condition in response to the material reaching a transition temperature.

In other embodiments, deformation strain control may be applied to the different segments along the length of the elongated member <NUM>. In particular, a first strain condition may be applied to a first set of segments (e.g., segments <NUM>, <NUM>, etc.) in such a way that the strain exceeds its recoverable limit of the Martensite phase, and therefore the Martensite phase cannot transfer to Austenite phase when the embolic device is deployed into the treatment site. These segments retain Martensite phase all the time, and therefore are considered to be irreversible Martensite segments. On the other hands, a second strain condition may be applied to a second set of segments (e.g., segments <NUM>, <NUM>, <NUM>, <NUM>, etc.) in such a way that the strain level is within their recoverable limit, and therefore the Martensite phase will transfer to Austenite phase when the embolic device <NUM> is deployed into the treatment site. These segments are therefore considered to be reversible Martensite segments.

In other embodiments, parts of the elongated member <NUM> may be covered by a shielding material while other parts of the elongated member <NUM> are chemically and/or heat treated. This allows different parts of the elongated member <NUM> to be formed having different mechanical properties. For example, this technique may be used to make irreversible Martensite segments and reversible Martensite segments along the length of the elongated member <NUM>.

In further embodiments, a combination of the above techniques may be employed to create the irreversible Martensite segments and the reversible Martensite segments along the length of the elongated member <NUM>.

Other techniques for shaping an elongated member may be used in other embodiments to form the embolic device <NUM>.

After the elongated member <NUM> has been formed to have the deployed shape (e.g., like the examples shown in <FIG> and <FIG>), and to have both irreversible Martensite segments (e.g., segments <NUM>, <NUM>, etc.) and reversible Martensite segments (e.g., segments <NUM>, <NUM>, <NUM>, <NUM>, etc.) along the length of the elongated member <NUM>, the elongated member <NUM> may be further treated to form a delivery shape (e.g., like the examples shown in <FIG> and <FIG>). In some embodiments, such may be accomplished using thermal cycling. For example, the elongated member <NUM> (already formed to have the deployed shape) may be subject to repeated heating and cooling while the elongated member <NUM> is placed in a desired delivery shape to be formed. In one technique, the elongated member <NUM> may be tensioned into a straight profile while subjecting it to repeated heating and cooling. In some embodiments, the heating may be performed heat the elongated member <NUM> to a temperature that is higher than <NUM>, or more preferably higher than <NUM> (e.g., <NUM>), or more preferably higher than <NUM>. Also, in some embodiments, the cooling may be performed to cool the elongated member <NUM> to a temperature that is below <NUM>, or more preferably below <NUM>, or more preferably below -<NUM>. This technique can be employed to create the embolic device <NUM> so that it has a first shape (delivery shape) when it is in room temperature, and a second shape (deployed shape) when it is in body temperature, such as when the embolic device <NUM> is deployed inside the patient. <FIG> is a stress-strain graph, particularly showing an effect of thermal cycling. As can be seen from the graph, when the elongated member <NUM> is subjected to heating and cooling, thermal stress is applied to the elongated member <NUM>, thereby shifting the stress-strain curve of the elongated member <NUM>. If the heating and cooling is repeated for additional cycle(s), additional thermal stress is applied to the elongated member <NUM>, thereby shifting the stress-strain curve further.

It should be noted that the transition temperature at which the embolic device <NUM> will change from the delivery shape to the deployed shape can be selectively configured using material composition and/or manufacturing process. For example, the Austenite finishing temperature may be selected for the manufacturing process for a certain given material so that the finished product will have a desired transition temperature.

<FIG> illustrate a method of using the medical device <NUM> of <FIG> to treat an aneurysm <NUM>. When using the medical device <NUM>, the catheter <NUM> is first inserted into a blood vessel <NUM> of a patient through an incision. The catheter <NUM> is then advanced distally until the distal end <NUM> of the catheter <NUM> is at the aneurysm <NUM>.

In some embodiments, the catheter <NUM> may be steerable. For example, the catheter <NUM> may include one or more steering wires configured to steer the distal end <NUM> of the catheter <NUM> in one or more directions. In other embodiments, the catheter <NUM> may not be steerable. Instead, a guidewire may first be used to access the target site. Then the catheter <NUM> may be disposed over the guidewire, and advanced distally using the guidewire. In such cases, the catheter <NUM> may include a separate channel for accommodating the guidewire.

After the distal end <NUM> of the catheter <NUM> is desirably placed, the shaft <NUM> (shown in <FIG>) is then advanced to push the embolic device <NUM> distally until a first distal portion of the embolic device <NUM> is outside the catheter <NUM> (<FIG>). The embolic device <NUM> has a straight profile when in room temperature residing inside the catheter <NUM>. The straight profile is due to the embolic device <NUM> being in room temperature, and it is not due to any mechanical straightening imposed by the catheter <NUM>. Accordingly, the embolic device <NUM> can be easier advanced distally. This feature also allows a longer embolic device <NUM> to be delivered if needed. As shown in the figure, the first portion of the elongated member <NUM> responds to body temperature by changing from its relatively straight shape to form a first part of the three-dimensional structure <NUM> when the first portion of the elongated member <NUM> is unconfined outside the catheter <NUM>. In particular, the reversible Martensite segments (e.g., segments <NUM>, <NUM>, <NUM>, <NUM>, etc.) along the elongated member <NUM> change phase to become Austenite segments in response to body temperature. These Austenite segments have curvilinear profiles to provide the delivery shape for the portions of the elongated member <NUM> that has been deployed. The irreversible Martensite segments (e.g., segments <NUM>, <NUM>, etc.) along the elongated member <NUM> remains in the Martensite phase. These irreversible Martensite segments are softer compared to the reversible Martensite segments, and therefore they are easier to be bent in response to force. Accordingly, as the first part of the three-dimensional structure <NUM> is delivered into the aneurysm, the loops of the three-dimensional structure <NUM> are pressed towards the wall of the aneurysm, which imposes a force onto the irreversible Martensite segments. These segments bend in response to the force, thereby allowing the delivered first part of the three-dimensional structure <NUM> to better conform to the shape of the aneurysm <NUM>.

In the illustrated example, the first part of the three-dimensional structure <NUM> has a shape that corresponds with an inner wall of the aneurysm. The first part of the three-dimensional structure <NUM>, represented schematically by the dashed line in <FIG>, provides a frame defining the cavity <NUM> for accommodating subsequent portions of the embolic device <NUM> to be delivered. As shown in the figure, the first part of the three-dimensional structure <NUM> also provides a scaffolding across a neck <NUM> of an aneurysm <NUM>, which assists in containing subsequent portion(s) of the elongated member <NUM> of the embolic device <NUM> to be delivered into the cavity <NUM>.

Next, the shaft <NUM> may be advanced further to push a subsequent portion of the embolic device <NUM> out of the catheter <NUM> (<FIG>). As shown in the figure, the subsequent portion forms a second part of the three-dimensional structure <NUM> when the subsequent portion is unconfined outside the catheter <NUM>. The second part of the three-dimensional structure <NUM> has a shape that allows it to fill at least some of the space in the cavity <NUM> defined by the first part of the three-dimensional structure <NUM>. As shown in the figure, the scaffolding across the neck <NUM> of the aneurysm provided by the first part of the three-dimensional structure <NUM> prevents the second part of the three-dimensional structure <NUM> from escaping or falling out of the cavity <NUM> of the first part of the three-dimensional structure <NUM> and out of the aneurysm.

As similarly discussed with reference to the first part of the three-dimensional structure <NUM>, for the second part of the three-dimensional structure <NUM>, the reversible Martensite segments along the elongated member <NUM> change phase to become Austenite segments in response to body temperature. These Austenite segments have curvilinear profiles to provide the delivery shape for the portions of the elongated member <NUM> that has been deployed. On the other hand, the irreversible Martensite segments along the elongated member <NUM> remains in the Martensite phase. These irreversible Martensite segments are softer compared to the reversible Martensite segments, and therefore they are easier to be bent in response to force. Accordingly, as the second part of the three-dimensional structure <NUM> is delivered into the aneurysm, the loops of the three-dimensional structure <NUM> are pressed towards the wall of the aneurysm (or towards the first part of the three-dimensional structure <NUM>), which imposes a force onto the irreversible Martensite segments. These segments bend in response to the force, thereby allowing the delivered second part of the three-dimensional structure <NUM> to better conform to the shape of the cavity to be filled.

In some embodiments, the distal end of the shaft <NUM> abuts against the proximal end of the elongated member <NUM>, and is not mechanically attached to the proximal end of the elongated member <NUM>. In such cases, the elongated member <NUM> becomes decoupled from the remaining part of the medical device <NUM> as soon as the proximal end of the elongated member <NUM> is pushed out of the catheter <NUM>. In other embodiments, the distal end of the shaft <NUM> may be mechanically connected to the proximal end of the elongated member <NUM>, such as via a mechanical connector that is operable to disengage the proximal end of the elongated member <NUM> from the shaft <NUM>. In further embodiments, the distal end of the shaft <NUM> may be mechanically connected to the proximal end of the elongated member <NUM> via a disintegratable link, such as a link that can be disintegrated in response to application of a current. Mechanical connectors and disintegratable links are well known in the art, and therefore will not be described in further detail.

As illustrated in the above embodiments, the embolic device <NUM> is advantageous because the softer individual discrete irreversible Martensite segments provide some flexibility for the embolic device <NUM>, thereby allowing the embolic device <NUM> to bend easily in response to force. While certain discrete parts (the irreversible Martensite segments) of the embolic device <NUM> can be more easily bent, a majority of other parts (i.e., the reversible Martensite segments) of the embolic device <NUM> remains relatively stiffer compared to the irreversible Martensite segments, thereby allowing the shape of most of the parts of the embolic device <NUM> to be maintained within the body cavity. In addition, the embolic device <NUM> is also advantageous because it has a delivery shape within the catheter <NUM> that is relatively straight compared to its deployed shape. This allows the embolic device <NUM> to be advanced distally relative to the catheter <NUM> easily without use of significant axial pushing force, and reduces the risk of the embolic device <NUM> buckling within the catheter <NUM>.

In some embodiments, multiple embolic devices <NUM> may be provided with different respective lengths. In such cases, before one of the embolic devices <NUM> is selected for treating an aneurysm, a doctor may measure a size of the aneurysm to be treated. For example, the doctor may perform measurement using one or more images of the aneurysm to determine the size of the aneurysm. The size may be a cross-sectional dimension of the aneurysm, a cross-sectional area of the aneurysm, a volume of the aneurysm, etc. After a size of the aneurysm has been determined, one of the embolic devices <NUM> may then be selected based on the size of the aneurysm. For example, a longer embolic device <NUM> may be selected to occlude a larger aneurysm.

<FIG> illustrates a method <NUM> of occluding a body lumen. The method <NUM> is performed by an embolic device having an elongated member, the elongated member comprising a first segment, a second segment, and a third segment, wherein the second segment is between the first segment and the third segment. The method <NUM> includes: undergoing a first shape change by the first segment of the elongated member in response to body temperature (item <NUM>); undergoing a second shape change by the second segment of the elongated member in response to force (item <NUM>); and undergoing a third shape change by the third segment of the elongated member in response to the body temperature (item <NUM>).

In some embodiments, the embolic device in the method <NUM> may be the embolic device <NUM> described herein.

Claim 1:
An embolic device (<NUM>) for placement in a body lumen, the embolic device (<NUM>) comprising:
an elongated member (<NUM>) having a linear configuration when at room temperature, the elongated member (<NUM>) being configured to form a first three-dimensional structure (<NUM>) in response to body temperature,
wherein room temperature refers to a temperature that is different from the body temperature,
wherein the elongated member (<NUM>) comprises a first segment (<NUM>), a second segment (<NUM>), and a third segment (<NUM>), the second segment (<NUM>) being located between the first segment (<NUM>) and the third segment (<NUM>),
wherein the first segment (<NUM>) is martensitic when the first segment (<NUM>) is at the room temperature, and is austenitic when the first segment (<NUM>) is at the body temperature, and
wherein the second segment (<NUM>) is martensitic when the second segment (<NUM>) is at the room temperature, and is also martensitic when the second segment (<NUM>) is at the body temperature;
wherein
the third segment (<NUM>) is martensitic when the third segment (<NUM>) is at the room temperature, and is austenitic when the third segment (<NUM>) is at the body temperature.