Hypotube with improved bending stiffness and tensile strength

Abstract

To provide a tubular support structure for an intravascular medical device with better flexibility and kink resistance. A tubular support structure (150a) for use in an elongated intravascular medical device includes an elongated tubular body (152), a patterned framework (156a) formed within the elongated tubular body (152), a lumen (158) disposed axially within the elongated tubular body (152), and a first set of floating tabs (160) spaced axially along the patterned framework (156a). Each of the first set of floating tabs (160) has a cantilevered end secured to the patterned framework (156a) and a free end configured to translate relative to and then engage the patterned framework (156a) when the tubular support structure (150a) is laterally deflected in a first bending direction.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to medical devices, and more particularly to support structures for intravascular medical devices. [Background technology]

[0002] The use of intravascular medical devices for accessing and treating various types of conditions, such as vascular disorders, is well known. For example, an appropriate intravascular catheter may be inserted into a patient's vascular system. In a commonly used vascular application to access a target site in a patient, a guidewire is inserted through an incision in the femoral artery near the groin and advanced until the target site is reached. An intravascular catheter is then advanced over the guidewire through the lumen of the intravascular catheter until the distal end of the intravascular catheter is positioned at the target site. Alternatively, the intravascular catheter may be introduced into the patient after the guidewire is withdrawn, leaving behind a guide sheath, allowing the intravascular catheter to navigate within the patient's vasculature within the guide sheath. When treating a vascular disorder, an intravascular implant may be advanced through the lumen of the catheter over a delivery wire, either simultaneously with or after the distal end of the intravascular catheter is positioned at the target site.

[0003] In certain applications, such as neurovascular treatments, intravascular medical devices such as guidewires, catheters, guide sheaths, and intravascular implant delivery wires are required to navigate tortuous and complex vasculature, including the relatively fragile vessels of the brain, often changing direction and even folding back on themselves. Therefore, such intravascular medical devices must possess adequate trackability, flexibility, pushability (axial stiffness), torqueability (rotational resistance), kink resistance, and pullability (tensile strength) to successfully navigate a patient's vasculature, including cerebral, coronary, and peripheral vessels. Trackability is a measure of an intravascular medical device's ability to pass through a patient's vasculature. Flexibility is a measure of the lateral bending stiffness along the length of the intravascular medical device and contributes significantly to the trackability of elongated intravascular medical devices. Pushability is a measure of the transfer of axial force applied proximally to the distal end of the intravascular medical device. Torqueability is a measure of the degree to which a proximally applied rotational force is transmitted to the distal end of an intravascular medical device, aiding in navigation through tortuous paths within a patient's vasculature. Kink resistance is a measure of the ability of an intravascular medical device to maintain its cross-sectional shape, particularly the lumen (if present), when bent about a radius. Pullability is a measure of the ability of an intravascular medical device to transmit axial tensile forces without plastically deforming or fracturing an elongated intravascular medical device.

[0004] The appropriate flexibility and kink resistance of these intravascular medical devices allow them to traverse moderate bends in the vasculature with relatively little tracking force (due to low lateral forces) and relatively tight bends without fracture, permanent deformation, or prolapse (due to adequate support and resistance). Furthermore, not only is it desirable to push these intravascular medical devices through the vasculature, but it may also be desirable to pull them through the vasculature if, for example, they become stuck (e.g., if they have escaped within a patient's vasculature, become trapped due to vasospasm, or interfere with another intravascular medical device) or if they are positioned in the wrong or undesired vessel within the vasculature. Therefore, it is important for such intravascular medical devices to have the necessary axial tensile strength to avoid fracture or plastic deformation. Any intravascular medical device must meet a minimum tensile strength for safe use. In many cases, meeting this tensile strength requires adding secondary elements to the elongated intravascular medical device or making existing elements more robust (larger or made of stronger material) than would otherwise be required, typically resulting in a stiffer device. Furthermore, the space occupied by these secondary strengthening elements or the stiffening of existing elements is unavailable for other elements that could improve device performance. Furthermore, these added tensile elements or more robust elements can increase the device's lateral bending stiffness, potentially adversely affecting other performance characteristics, such as trackability. Therefore, performance benefits can be achieved by improving tensile strength through performance-specific design of existing elements within the elongated intravascular medical device. Thus, by using appropriately sized intravascular medical devices with the required performance characteristics, such as pushability, torqueability, pullability, and distal tip flexibility, virtually any target site within the vasculature, including the tortuous cerebral and peripheral vasculature, can be accessed. However, balancing these performance characteristics can be challenging.

[0005] Many microcatheters and guidewires with hypotubes currently being designed attempt to achieve this balance. Hypotubes are typically elongated, thin-walled tubes made of metals or metal alloys, such as stainless steel or nickel-titanium alloys (e.g., nitinol). Hypotubes are often micromachined along their length. The distal end of the hypotube may have a slotted pattern that enhances flexibility while providing sufficient axial stiffness to maintain the hypotube's pushability through the patient's vasculature. In some cases, a polymer jacket is applied to the outer diameter of the hypotube slots to provide a tight seal and minimize the roughness of the hypotube's outer surface while allowing flexibility. This outer jacket may also fill the hypotube's openings and slots and coat the hypotube's inner surface. In applications such as neurovascular interventions, where the catheter carries various other devices, drugs, and fluids to the patient's body cavities or cavities, the properties of the catheter's inner lumen can significantly affect its performance. In particular, the lubricity of the inner surface can affect the ability of other devices, drugs, and / or fluids to pass through the catheter's lumen. To enhance lubricity, a low-friction inner polymer liner (e.g., polytetrafluoroethylene (PTFE)) may surround the catheter lumen, providing a lubricious inner surface to facilitate the passage of guidewires, pacing leads, and other devices through the catheter lumen.

[0006] While such slotted hypotube designs generally achieve a good balance between pushability, pullability, torqueability, kink resistance, and distal tip flexibility, there is still room for improvement. For example, slotted hypotube designs generally have a relatively low, isotropic bending stiffness (i.e., bending stiffness that is the same in all radial directions), allowing elongated medical devices to be easily advanced through small to moderate curvatures in the vasculature with low compliance forces. However, even such intravascular medical devices are prone to deviation when introduced into tightly curved vasculature. Furthermore, the slot pattern in the hypotube typically creates ribs or struts that are lateral or perpendicular to the longitudinal axis of the hypotube. Therefore, when such slotted hypotubes are subjected to tensile forces (e.g., when the elongated medical device is pulled), lateral bending forces are exerted on the ribs or struts of the support structure. These lateral forces typically generate high bending moments, resulting in high localized stresses in the tubular structure. Therefore, when a tensile force is applied to a slotted hypotube, the ribs and struts are prone to deformation, resulting in plastic deformation and fracture of the elongated medical device at relatively low tensile forces. Furthermore, if an intravascular medical device is prone to stretching under tension, whether elastic or plastic, it will be less precise in its navigation within the vasculature and perform poorly. Therefore, slotted hypotubes may need to be constructed from relatively high-strength but relatively stiff materials (e.g., metals such as stainless steel) rather than flexible but low-strength materials (e.g., metal alloys such as nickel-titanium (nitinol)). Therefore, the tensile strength and stiffness of such slotted hypotubes have generally had to be sacrificed to provide the slotted hypotube with sufficient bending flexibility.

[0007] Thus, there is a need for a slotted hypotube design that overcomes the above-mentioned challenges. Summary of the Invention

[0008] The present invention includes a tubular support structure for use in an elongated intravascular medical device. The tubular support structure includes an elongated tubular body (e.g., a hypotube), a patterned framework formed within the elongated tubular body, and a lumen disposed axially within the elongated tubular body. In one embodiment, the patterned framework has a plurality of substantially transverse slots disposed at least partially within the elongated tubular body, the substantially transverse slots being axially spaced along the tubular support structure, thereby forming a plurality of substantially transverse members and a plurality of connecting members rigidly connecting the substantially transverse members to one another. The connecting members extend axially along the patterned framework, and the substantially transverse slots may be disposed entirely through the elongated tubular body. One embodiment of an elongated intravascular medical device may include an elongated polymer tube and the tubular support structure disposed coaxially within the polymer tube. In this embodiment, the tubular support structure may be disposed at the distal end of the polymer tube or may be disposed proximal to the distal end of the polymer tube. Another embodiment of an elongate intravascular medical device may include a core wire and the tubular support structure disposed on the distal end of the core wire. Yet another embodiment of an elongate intravascular medical device may include the tubular support structure and an inner polymer liner disposed within the lumen of the tubular body of the tubular support structure.

[0009] According to a first aspect of the present invention, the tubular support structure includes a first set of floating tabs spaced axially along the patterned framework, each of the first set of floating tabs having a cantilevered end secured to the patterned framework (e.g., a substantially transverse member of the patterned framework) and a free end configured to translate relative to and then engage the patterned framework as the tubular support structure deflects laterally in a first bending direction. The first set of floating tabs may, for example, be circumferentially aligned on the patterned framework or circumferentially offset on the patterned framework.

[0010] In one embodiment, each of the first set of floating tabs is configured to translate relative to the patterned frame structure when the tubular support structure is in a primary lateral deflection range and to engage the patterned frame structure when the tubular support structure is in a secondary lateral deflection range that is greater than the primary lateral deflection range. In this embodiment, the tubular support structure has a primary bending stiffness (e.g., 0.00001 in) when the tubular support structure is in the primary lateral deflection range. 2 -lb) and one or more secondary bending stiffnesses greater than the primary bending stiffness when the tubular support structure is in a secondary lateral deflection range. The maximum value of the secondary bending stiffnesses may be no more than five times, and preferably no more than two times, the primary bending stiffness. In this embodiment, the primary bending stiffnesses are radially isotropic, while the secondary bending stiffnesses are each radially anisotropic, and each secondary bending stiffness may have at least one relatively low circumferential region and at least one relatively high circumferential region. The magnitude of each of the relatively low circumferential regions may be equal to or greater than the magnitude of the primary bending stiffness.

[0011] In another embodiment, as the tubular support structure is axially stretched, the free end of each of the first set of floating tabs is configured to translate relative to and then engage with the patterned framework structure. In this embodiment, each of the first set of floating tabs may be configured to translate relative to the patterned framework structure when the tubular support structure is in a first range of axial extension and to engage with the patterned framework structure when the tubular support structure is in a second range of axial extension greater than the first range of axial extension. The tubular support structure may have a first tensile stiffness when the tubular support structure is in the first range of axial extension and one or more second tensile stiffnesses greater than the first tensile stiffness when the tubular support structure is in the second range of axial extension.

[0012] In yet another embodiment, the first set of floating tabs are configured to incrementally engage the patterned frame structure as the tubular support structure deflects laterally in a first bending direction. For example, at least two of the floating tabs may be of different lengths. In yet another embodiment, the tubular support structure further includes a second set of floating tabs axially spaced along the patterned frame structure and circumferentially offset from the first set of floating tabs. Each of the second set of floating tabs may have a cantilevered end fixed to the patterned frame structure (e.g., a substantially transverse member of the patterned frame structure) and a free end configured to translate relative to and then engage the patterned frame structure as the tubular support structure laterally deflects in a second bending direction different from the first bending direction. In this embodiment, the second set of floating tabs may be circumferentially offset 180 degrees from the first set of floating tabs, and the second bending direction may be opposite to the first bending direction. In this embodiment, the first set of floating tabs may be configured to translate relative to the patterned frame structure in a first axial direction when the tubular support structure is laterally deflected in a first direction, and the second set of floating tabs may be configured to translate relative to the frame in a second axial direction opposite the first axial direction. For example, the first set of floating tabs may be configured to continue to translate relative to the patterned frame structure in a first axial direction after all of the second set of floating tabs have engaged the patterned frame structure, and the second set of floating tabs may be configured to continue to translate relative to the patterned frame structure in a second axial direction after all of the first set of floating tabs have engaged the patterned frame structure.

[0013] In yet another embodiment, each of the first set of floating tabs includes a stem element and an enlarged element that respectively form the cantilevered end and the free end of the respective tab. For example, each of the first set of floating tabs may be T-shaped. In this embodiment, the patterned framework may include a plurality of retainer openings at least partially disposed within the elongated tubular body, and the enlarged portion of each of the first set of floating tabs may be configured to advance into one of the retainer openings and then engage an abutting edge of the respective retainer opening as the tubular support structure is laterally deflected in a first bending direction. Each retainer opening may be coaxial with a respective one of the substantially transverse slots, in which case each stem element of the first set of floating tabs may extend from a respective transverse member, across one of the substantially transverse slots, and into a respective retainer opening. Each of a pair of adjacent substantially transverse members may include a pair of extensions forming a channel between one of the retainer openings and one of the substantially transverse slots, where the stem element of each of the first set of floating tabs fits within one of the channels and each pair of extensions may define an abutment edge of a respective retainer opening. Each pair of extensions may be configured to flex laterally when the enlarged element of the respective floating tab engages the abutment edge of the respective retainer opening.

[0014] According to a second aspect of the present invention, the tubular support structure includes a first set of mechanical property modulating elements axially spaced along the patterned frame structure, the first set of mechanical property modulating elements modulating a finite bending stiffness (e.g., 0.00001 in) of the tubular support structure in response to lateral deflection of the tubular support structure in a first bending direction. 2 -lb). The infinite bending stiffness of the tubular support structure may be increased, for example, by less than 500%, preferably less than 200%. The first set of mechanical property modulating elements may be, for example, circumferentially aligned on the patterned framework or may be circumferentially offset on the patterned framework.

[0015] In one embodiment, each of the first set of mechanical property modulating elements comprises a floating tab having a cantilevered end fixed to the patterned framework and a free end configured to translate relative to the patterned framework and then engage the patterned framework as the tubular support structure deflects laterally in a first bending direction, thereby increasing the finite bending stiffness of the tubular support structure.

[0016] In another embodiment, the first set of mechanical property modulation elements is further configured to increase a finite tensile stiffness of the tubular support structure in response to axial stretching of the tubular support structure. In yet another embodiment, the first set of mechanical property modulation elements is configured to increase a finite bending stiffness of the tubular support structure multiple times in response to laterally deflecting the tubular support structure in a first bending direction.

[0017] In yet another embodiment, the finite bending stiffness of the patterned tubular support structure increases from an initial radially isotropic primary bending stiffness to a radially anisotropic secondary bending stiffness, the secondary bending stiffness having at least one relatively low circumferential region and at least one relatively high circumferential region, in which the magnitude of each of the relatively low circumferential regions may be equal to or greater than the magnitude of the primary bending stiffness.

[0018] In yet another embodiment, the tubular support structure further includes a second set of mechanical property modulation elements axially spaced along the patterned frame structure and circumferentially offset from the first set of mechanical property modulation elements. The second set of mechanical property modulation elements is configured to progressively increase a second bending stiffness of the tubular support structure in response to laterally deflecting the tubular support structure in a second bending direction different from the first bending direction. In this embodiment, the second set of mechanical property modulation elements is circumferentially offset 180 degrees from the first set of mechanical property modulation elements, and the second bending direction is opposite to the first bending direction. In this case, the second mechanical property modulation elements may not contribute to an increase in the primary bending stiffness of the tubular support structure when the tubular support structure is laterally deflected in the first bending direction, and the first mechanical property modulation elements may not contribute to an increase in the secondary bending stiffness of the tubular support structure when the tubular support structure is laterally deflected in the second bending direction.

[0019] According to a third aspect of the present invention, the tubular support structure includes a first set of mechanical property modulation elements spaced circumferentially around the patterned framework. The first set of mechanical property modulation elements is configured to incrementally increase the finite tensile stiffness of the tubular support structure (e.g., greater than 0.05 pounds) in response to axial stretching of the tubular support structure. The finite tensile stiffness of the tubular support structure can be increased, for example, by 50% or more, preferably 100% or more. The first set of mechanical property modulation elements can be, for example, circumferentially aligned on the patterned framework.

[0020] In one embodiment, each of the first set of mechanical property modulating elements includes a floating tab having a cantilevered end fixed to the patterned frame structure and a free end configured to translate relative to the patterned frame structure as the tubular support structure stretches axially and then engage the patterned frame structure, thereby increasing the finite tensile stiffness of the tubular support structure.

[0021] In another embodiment, the tubular support structure further includes a second set of mechanical property modulation elements circumferentially spaced about the patterned framework and axially spaced from the first set of mechanical property modulation elements, the second mechanical property modulation elements configured to further increase the finite tensile stiffness of the tubular support structure in response to axial stretching of the tubular support structure.

[0022] In yet another embodiment, the first and second sets of mechanical property modulating elements are configured to incrementally increase the finite tensile stiffness of the tubular support structure multiple times in response to axial stretching of the tubular support structure. In yet another embodiment, the tubular support structure has a finite bending stiffness that gradually increases with increasing finite tensile stiffness, for example, the first set of mechanical property modulation elements can be configured to have a finite bending stiffness that gradually increases with increasing finite tensile stiffness.

[0023] According to a fourth aspect of the present invention, the tubular support structure comprises a plurality of mechanical property modulating elements disposed on the patterned framework (e.g., secured to substantially transverse members of the patterned framework) configured to modulate a radially isotropic bending stiffness of the tubular support structure in response to laterally deflecting the patterned framework in one or more bending directions, such that the tubular support structure has a radially anisotropic bending stiffness.

[0024] In one embodiment, each of the plurality of mechanical property modulating elements comprises a floating tab having a cantilevered end fixed to the patterned framework and a free end configured to translate relative to the patterned framework and then engage the patterned framework as the tubular support structure deflects laterally in a first bending direction, thereby modulating the radially isotropic bending stiffness of the tubular support structure.

[0025] In another embodiment, the plurality of mechanical property modulating elements includes one or more sets of mechanical property modulating elements, each set of mechanical property modulating elements spaced axially along the framework, each set of mechanical property modulating elements configured to adjust the radial isotropic bending stiffness of the tubular support structure in response to laterally deflecting the tubular support structure in one or more bending directions, respectively.

[0026] In yet another embodiment, the set of mechanical property modulation elements comprises multiple sets of mechanical property modulation elements circumferentially offset from one another around the patterned frame structure, and the bending direction comprises multiple different bending directions. In this embodiment, two of the multiple sets of mechanical property modulation elements may be circumferentially offset by 180 degrees from one another. In this case, each of the radially anisotropic secondary bending stiffnesses may have at least one relatively low circumferential region and at least one relatively high circumferential region. The magnitude of each of the relatively low circumferential regions may be equal to or greater than the magnitude of the primary bending stiffness. Each of the relatively low circumferential regions may be located at a circumferential position of the patterned frame structure where the set of mechanical property modulation elements is not present, and each of the relatively high circumferential regions may be centered on a circumferential position of the patterned frame structure where the set of mechanical property modulation elements is present. Each of the relatively low intensity circumferential regions may be centered on a circumferential position of the patterned frame structure where a first set of the plurality of mechanical property modulating elements is present, and each of the relatively high intensity circumferential regions may be centered on a circumferential position of the patterned frame structure where a second set of the plurality of mechanical property modulating elements is present, where the first and second sets of mechanical property modulating elements may modulate the patterned frame structure in different manners.

[0027] The present invention also includes a method of distally advancing an elongated intravascular medical device (e.g., a guidewire, catheter, guide sheath, or intravascular implant delivery wire) within a patient's vasculature. The method includes introducing the elongated intravascular medical device into the patient's vasculature and distally advancing a longitudinal portion of the elongated intravascular medical device into a first curve within the patient's vasculature. The longitudinal portion may be, for example, the distal end of the elongated intravascular medical device or may be proximal to the distal end of the elongated intravascular medical device. The method further includes distally advancing the longitudinal portion of the elongated intravascular medical device into a second curve within the patient's vasculature. The second curve has a curvature greater than the curvature of the first curve. The method further includes distally advancing the elongated intravascular medical device within the patient's vasculature until the distal end of the elongated intravascular medical device is located at a target site within the patient's vasculature. A method may further include performing an additional medical procedure at a target site using the elongated intravascular medical device.

[0028] According to a fifth aspect of the present invention, the length of the elongate intravascular medical device has a primary bending stiffness when advanced distally through a first curve in the patient's vasculature. The method further includes transitioning the primary bending stiffness of the length of the elongate intravascular medical device to a secondary bending stiffness greater than the primary bending stiffness in response to the length of the elongate intravascular medical device advancing distally through a second curve. For example, the peak secondary bending stiffness may be less than 500%, preferably less than 200%, of the primary bending stiffness.

[0029] In one method, the length of the elongate intravascular medical device has a patterned framework that provides the elongate intravascular medical device with the primary bending stiffness and the secondary bending stiffness, and the elongate intravascular medical device has mechanical property-modulating elements axially spaced along the patterned framework, wherein the mechanical property-modulating elements are configured to transition from the primary bending stiffness to the secondary bending stiffness in response to distal advancement of the length of the elongate intravascular medical device within a second curve.

[0030] Another method further includes advancing the length of the elongate intravascular medical device distally into a third curve in the patient's vasculature, the third curve having a curvature less than the curvature of the second curve, wherein the method further includes transitioning a secondary bending stiffness of the elongate intravascular medical device length to the primary bending stiffness in response to distal advancement of the elongate intravascular medical device length within the third curve. The method may further include advancing the length of the elongate intravascular medical device distally into a fourth curve in the patient's vasculature, the fourth curve having a curvature greater than the curvature of the first curve and different from the curvature of the second curve, wherein the method further includes transitioning a primary bending stiffness of the elongate intravascular medical device length to another bending stiffness different from the secondary bending stiffness in response to distal advancement of the elongate intravascular medical device length through the fourth curve.

[0031] Yet another method further includes the steps of pulling the elongate intravascular medical device and, in response to pulling the elongate intravascular medical device, transitioning a primary tensile stiffness of a lengthwise portion of the elongate intravascular medical device to a secondary tensile stiffness greater than the primary tensile stiffness.

[0032] In yet another method, the secondary bending stiffness of the length of the elongate intravascular medical device is radially anisotropic, having circumferential regions of relatively low and relatively high secondary bending stiffness. The method further includes rotating the elongate intravascular medical device about its longitudinal axis such that the primary bending stiffness of the length of the elongate intravascular medical device transitions to the circumferential region of relatively high secondary bending stiffness as the rotated length of the intravascular medical device advances distally through a second curve. In this method, the magnitude of the circumferential region of relatively low secondary bending stiffness is equal to or greater than the magnitude of the primary bending stiffness. The method may further include, prior to the step of rotating the elongated intravascular medical device about its longitudinal axis, advancing a length portion of the elongated intravascular medical device distally into a second curved portion while the length portion of the elongated intravascular medical device has a circumferential region with a relatively low degree of secondary bending stiffness such that the length portion of the elongated intravascular medical device cannot be successfully advanced distally through the second curved portion, and retracting the length portion of the elongated intravascular medical device proximally.

[0033] According to a sixth aspect of the present invention, the length of the elongate intravascular medical device has a radially isotropic bending stiffness when advanced distally within a first curve in the patient's vasculature, the method further comprising transitioning the radially isotropic bending stiffness of the length of the elongate intravascular medical device to a radially anisotropic bending stiffness in response to the length of the elongate intravascular medical device advancing distally within the second curve.

[0034] In one method, the length of the elongate intravascular medical device has a patterned framework that imparts a radially isotropic bending stiffness to the elongate intravascular medical device, and the elongate intravascular medical device has mechanical property-modulating elements axially spaced along the patterned framework, the mechanical property-modulating elements configured to transition from the radially isotropic bending stiffness to a radially anisotropic bending stiffness in response to distal advancement of the length of the elongate intravascular medical device within a second curve.

[0035] Another method further includes the steps of distally advancing a length of the elongate intravascular medical device into a third curve within the patient's vasculature, the third curve having a curvature less than the curvature of the second curve, and transitioning the radially anisotropic bending stiffness of the elongate intravascular medical device length into a radially isotropic bending stiffness in response to distal advancement of the elongate intravascular medical device length within the third curve. In this method, the radially anisotropic bending stiffness can have circumferential regions of relatively low and relatively high bending stiffness, in which case the method further includes rotating the elongate intravascular medical device about its longitudinal axis, such that the radially isotropic bending stiffness of the elongate intravascular medical device length transitions to a circumferential region of relatively high bending stiffness as the rotated intravascular medical device length is advanced distally within the second curve. In this method, the magnitude of the circumferential region of relatively low secondary bending stiffness is equal to or greater than the magnitude of the primary bending stiffness. The method may further include, prior to rotating the elongated intravascular medical device about its longitudinal axis, advancing the length of the elongated intravascular medical device distally to a second curve with the circumferential region having a relatively low secondary bending stiffness such that the length of the elongated intravascular medical device cannot be successfully advanced distally through the second curve, and retracting the length of the elongated intravascular medical device proximally.

[0036] Other and further aspects and features of the embodiments will become apparent from the following detailed description considered in conjunction with the accompanying figures. [Brief explanation of the drawings]

[0037] The drawings illustrate the design and utility of preferred embodiments of the disclosed invention, with like elements being referred to by common reference numerals. Note that the figures are not drawn to scale, and that elements of similar structure or function are represented by like reference numerals throughout the drawings. Also, note that the drawings are intended to facilitate explanation of the embodiments. They are not intended to be an exhaustive description of the invention or to limit the scope of the invention, which is defined solely by the appended claims and their equivalents. Moreover, illustrated embodiments of the disclosed invention need not possess all illustrated aspects or advantages. Furthermore, aspects or advantages discussed in connection with a particular embodiment of the disclosed invention are not necessarily limited to that embodiment, and may be practiced in other embodiments, even if not illustrated.

[0038] In order to better understand how the above and other advantages and objects of the disclosed invention are obtained, the foregoing brief description of the disclosed invention will be more particularly described by reference to specific embodiments illustrated in the accompanying drawings, in which: The invention will be described with further specificity and detail through the use of the accompanying drawings, it being understood that these drawings illustrate only typical embodiments of the invention and are therefore not intended to limit its scope.

[0039] [Figure 1] FIG. 1 is a plan view of one embodiment of a guidewire constructed in accordance with the present invention, particularly showing the distal portion of the guidewire in a straight configuration. [Figure 2] FIG. 2 is a plan view of the guidewire of FIG. 1, particularly showing the distal portion of the guidewire in a curved configuration. [Figure 3] 3 is a longitudinal cross-sectional view of the distal portion of the guidewire of FIG. 1. FIG. [Figure 4] FIG. 4 is a plan view of one embodiment of a catheter constructed in accordance with the present invention, particularly showing the distal portion of the catheter in a straight configuration. [Figure 5] FIG. 5 is a plan view of the catheter of FIG. 4, particularly showing the distal portion of the catheter in a curved configuration. [Figure 6] FIG. 6 is a longitudinal cross-sectional view of the distal portion of the catheter of FIG. [Figure 7] FIG. 7 is a side view of one embodiment of a tubular support structure for use in the guidewire of FIGS. 1-3 or the catheter of FIGS. 4-6, specifically having four circumferentially aligned rows of mechanical property-modulating elements. [Figure 8] FIG. 8 is a side view of the tubular support structure of FIG. 7, particularly illustrating lateral deflection of the tubular support structure. [Figure 9] FIG. 9 is a side view of the tubular support structure of FIG. 7, particularly showing the tubular support structure in an axially extended configuration. [Figure 10] FIG. 10 is an axial view of the tubular support structure of FIG. [Figure 11] FIG. 11 is a plan view illustrating the radially isotropic first order bending stiffness and the radially isotropic second order bending stiffness of the tubular support structure of FIG. [Figure 12] FIG. 12 is a side view of another embodiment of a tubular support structure for use in the guidewire of FIGS. 1-3 or the catheter of FIGS. 4-6, specifically having four circumferentially offset sets of mechanical property-modulating elements. [Figure 13] FIG. 13 is a side view of yet another embodiment of a tubular support structure for use in the guidewire of FIGS. 1-3 or the catheter of FIGS. 4-6, specifically having two circumferentially aligned sets (rows) of mechanical property-modulating elements. [Figure 14] FIG. 14 is an axial view of the tubular support structure of FIG. [Figure 15] FIG. 15 is a plan view illustrating the radially isotropic first order bending stiffness and the radially anisotropic second order bending stiffness of the tubular support structure of FIG. [Figure 16]FIG. 16 is a side view of yet another embodiment of a tubular support structure for use in the guidewire of FIGS. 1-3 or the catheter of FIGS. 4-6, specifically having a single circumferentially aligned set (row) of mechanical property-modulating elements. [Figure 17] FIG. 17 is an axial view of the tubular support structure of FIG. [Figure 18] FIG. 18 is a plan view illustrating the radially isotropic first order bending stiffness and the radially anisotropic second order bending stiffness of the tubular support structure of FIG. [Figure 19] FIG. 19 is a plan view illustrating the radially isotropic first order bending stiffness and the radially anisotropic second order bending stiffness of the tubular support structure of FIG. [Figure 20] FIG. 20 illustrates uniform (first order) and incremental (second order) bending stiffness plotted against lateral deflection for the tubular support structure of FIG. [Figure 21] FIG. 21 shows the uniform (first order) and incremental (second order) tensile stiffness plotted against axial stretch for the tubular support structure of FIG. [Figure 22] Figure 22A is an enlarged view of the mechanical property modulation element and patterned framework of the tubular support structure of Figure 7, particularly illustrating the relative positions of the mechanical property modulation element and patterned framework when the tubular support structure is relaxed. Figure 22B is an enlarged view of the mechanical property modulation element and patterned framework of Figure 22A, particularly illustrating the relative positions of the mechanical property modulation element and patterned framework when the tubular support structure is laterally deflected or axially stretched. [Figure 23] FIG. 23 is a perspective view of one particular embodiment of the tubular support structure of FIG. [Figure 24] 24 is another perspective view of the tubular support structure of FIG. 23. FIG. [Figure 25] FIG. 25 is a side view of the tubular support structure of FIG. [Figure 26] FIG. 26 is a side view of the tubular support structure of FIG. 25, particularly illustrating lateral deflection of the tubular support structure. [Figure 27]27 is a partial cutaway perspective view of the tubular support structure of FIG. 23. FIG. [Figure 28] Figure 28A is a close-up view of one embodiment of a mechanical property modulation element of the tubular support structure of Figure 23, particularly illustrating the positional relationship between the mechanical property modulation element and the patterned frame structure when the tubular support structure is relaxed. Figure 28B is a close-up view of the mechanical property modulation element of Figure 28A, particularly illustrating the positional relationship between the mechanical property modulation element and the patterned frame structure when the tubular support structure is laterally deflected or axially stretched. [Figure 29] FIG. 29 is a side view of another specific embodiment of the tubular support structure of FIG. [Figure 30] FIG. 30 is a perspective view of yet another specific embodiment of the tubular support structure of FIG. [Figure 31] 31 is a partial cutaway perspective view of the tubular support structure of FIG. 30. FIG. [Figure 32] FIG. 32 is a perspective view of yet another specific embodiment of the tubular support structure of FIG. [Figure 33] FIG. 33 is a perspective view of yet another specific embodiment of the tubular support structure of FIG. [Figure 34] FIG. 34 is a side view of the tubular support structure of FIG. [Figure 35] FIG. 35 is a perspective view of yet another specific embodiment of the tubular support structure of FIG. [Figure 36] FIG. 36 is a side view of the tubular support structure of FIG. [Figure 37]Figure 37A is an enlarged view of another embodiment of a mechanical property modulation element of the tubular support structure of Figure 23, particularly illustrating the positional relationship between the mechanical property modulation element and the patterned framework structure when the tubular support structure is relaxed. Figure 37B is an enlarged view of the mechanical property modulation element of Figure 37A, particularly illustrating the positional relationship between the mechanical property modulation element and the patterned framework structure when the tubular support structure is laterally deflected or axially stretched in one direction. Figure 37C is an enlarged view of the mechanical property modulation element of Figure 37A, particularly illustrating the positional relationship between the mechanical property modulation element and the patterned framework structure when the tubular support structure is laterally deflected or axially stretched in the opposite direction. [Figure 38] FIG. 38 is a flow diagram illustrating one method of using an elongated intravascular medical device incorporating the tubular support structure of FIG. 7 within a patient's vasculature. [Figure 39] 39A-39J are plan views illustrating use of an elongated intravascular medical device within a patient's vasculature in accordance with the method of FIG. [Figure 40] FIG. 40 is a flow diagram illustrating another method of using an elongated intravascular medical device incorporating the tubular support structure of FIG. 7 within a patient's vasculature. [Figure 41] 41A-41H are plan views illustrating the use of an elongated intravascular medical device within a patient's vasculature in accordance with the method of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0040] The present disclosure describes a tubular support structure in the form of a slotted hypotube that can be incorporated into an elongated intravascular medical device (e.g., at the distal end, proximal end, and / or any region therebetween) to navigate through a patient's tortuous and complex vasculature. The tubular support structure can be incorporated into any size intravascular medical device, from guidewires to working or diagnostic catheters to guide sheaths. The tubular support structure can also be incorporated into any moving part of the intravascular medical device, such as an intravascular implant delivery wire. As described in more detail below, the mechanical properties of the tubular support structure are dynamically adjusted in response to lateral deflection and / or axial stretch of the tubular support structure. In this manner, an intravascular medical device incorporating the tubular support structure will exhibit the dynamically adjusted mechanical properties of the tubular support structure.

[0041] For example, through the inherent characteristics of the tubular support structure, the bending stiffness of the tubular support structure increases in response to lateral deflection of the tubular support structure, and the tensile stiffness of the tubular support structure increases in response to axial stretching of the tubular support structure. Thus, an intravascular medical device incorporating this tubular support structure can have a relatively low primary bending stiffness to easily advance with low tracking forces through small to moderate bends in a patient's vasculature, and a relatively high secondary bending stiffness to prevent dislodgement when navigating tight bends in a patient's vasculature.

[0042] Furthermore, the tensile stiffness, and therefore the tensile strength, of such a tubular support structure increases as the elongated intravascular medical device is stretched axially, thereby resisting deformation of the elongated intravascular medical device even when large tensile forces are applied to the elongated intravascular medical device. The tubular support structure can self-limit the amount of bending moment that can be applied to the strut transverse ribs, thereby increasing the tensile strength for a given initial bending stiffness. Thus, the tubular support structure can be constructed of a more flexible material without sacrificing the tensile strength of the tubular support structure, and intravascular medical devices incorporating the tubular support structure can have both relatively high bending flexibility and relatively high tensile strength, contrary to the notion that two opposing mechanical properties must be compromised to achieve a balance.

[0043] The bending stiffness of the tubular support structure can also be adjusted to have a radially isotropic primary bending stiffness and a radially anisotropic secondary bending stiffness. Accordingly, the bending stiffness of an elongated intravascular medical device incorporating the tubular support structure can be selected when traversing a curve in a patient's vasculature by rotating the elongated intravascular medical device about its axis. For example, a low bending stiffness of the elongated intravascular medical device can be selected when attempting to traverse a tight curve in a patient's vasculature, and if such an attempt fails (e.g., if a diversion event occurs), the elongated intravascular medical device can be rotated to increase its bending stiffness and the attempt to traverse the tight curve in the patient's vasculature can be repeated.

[0044] 1-2, an embodiment of an intravascular guidewire 10 incorporating the above-described tubular support structure will be described. These may be used in combination with another medical device, e.g., in the form of a catheter, for intravascular procedures to treat and / or diagnose a medical condition within a patient. Of course, as an alternative, the guidewire 10 may be used in any of a variety of ways within a patient's vasculature. For example, the guidewire 10 may be configured to deliver an implant (not shown), in which case the guidewire 10 may function as a delivery wire or pushwire slidably disposed within the lumen of a delivery catheter. As another alternative, the guidewire 10 may be used to cross an occlusion or stenosis within a patient's vasculature. The guidewire 10 may be suitable for use in neurointerventions, coronary interventions, peripheral interventions, and the like.

[0045] The guidewire 10 generally comprises an elongated guidewire body 12 having a proximal section 14 and a distal section 16. The free end of the proximal section 14 of the guidewire body 12 remains external to the patient and is accessible to an operator (e.g., a clinician or physician), while the remainder of the guidewire body 12, including the distal section 16, is sized and dimensioned to reach remote locations in the patient's vasculature. A torquer 18 may be attached to the free end of the proximal section 14 of the guidewire body 12 to apply torque to the guidewire 10 during a medical procedure. The torquer 18 is shaped to be ergonomically grasped between the operator's thumb and index finger and manipulated to push, pull, or rotate the guidewire body 12. The torquer 18 may be repositioned as needed as the guidewire 10 advances through the patient's vasculature.

[0046] The guidewire body 12 has a length suitable for accessing a target tissue site within a patient from a vascular access point. The target tissue site will vary depending on the medical procedure for which the guidewire 10 is being used. As such, the size of the guidewire 10 can be appropriately sized for any given intervention. For example, the guidewire 10 can have an appropriate length (e.g., 100-450 cm) and an appropriate diameter (e.g., 1F-3F). In one embodiment, the outer diameter of the guidewire body 12 can be uniform along its length. In another embodiment, the outer diameter of the guidewire body 12 can taper gradually or stepwise from a first outer diameter at the proximal portion 14 to a second outer diameter at the distal portion 16 to facilitate navigation through tortuous vasculature. While the guidewire body 12 is depicted as having a generally circular cross-sectional shape, it should be understood that the guidewire body 12 can include other cross-sectional shapes or combinations of shapes, such as, for example, an oval, a rectangle, a triangle, a polygon, etc.

[0047] Guidewire body 12 has a straight configuration that is relatively straight at room and / or body temperature but flexes when subjected to an external force, allowing guidewire body 12 to be advanced through a patient's vasculature. Guidewire body 12 has a transitional stiffness section that gradually decreases in stiffness from high stiffness in proximal portion 14 to low stiffness along distal portion 16, allowing for sufficient pushability for advancement through a patient's vasculature and torqueability for transmitting rotational forces to distal portion 16, allowing for easy transition between the straight configuration ( FIG. 1 ) and the curved configuration ( FIG. 2 ).

[0048] 3, the guidewire body 12 comprises a core wire 20 having a proximal portion 22 and a distal portion 24, a tubular support structure 26 secured over the distal portion 24 of the core wire 20, a radiopaque coil 28 secured within the tubular support structure 26 to the distal portion 24 of the core wire 20, and an atraumatic distal tip member 30 secured to the distal tip 30 of the core wire 20 and / or the tubular support structure 26 via a solder joint 32. The radiopaque coil 28 may be constructed of a suitable radiopaque material, such as gold, platinum, palladium, tantalum, tungsten alloy, a polymeric material filled with a radiopaque filler, or the like. The distal tip member 30 may be, for example, a solder ball or in the form of a polymeric tip disposed on the end of the core wire 20.

[0049] Tubular support structure 26 has a slot pattern designed to enhance the flexibility of guidewire body 12 while ensuring adequate torque transmission characteristics. In the illustrated embodiment, the slot pattern extends substantially the entire length and circumference of tubular support structure 26; however, the slot pattern may alternatively extend along any length or circumference of tubular support structure 26. While tubular support structure 26 is illustrated as being disposed at distal portion 16 of guidewire body 12, it should be understood that tubular support structure 26 may be disposed anywhere in guidewire body 12, including at proximal portion 14 of guidewire body 12, if dynamic adjustment of the mechanical properties (particularly bending stiffness and tensile strength) of guidewire body 12 is desired. Further details of the structure and function of tubular support structures that can be used as tubular support structure 26 for guidewire body 12 are described in more detail below.

[0050] In the illustrated embodiment, core wire 20 is a unitary member. Distal portion 24 of core wire 20 includes a tapered portion that gradually decreases in length so as to gradually increase the flexibility of distal portion 16 of guidewire body 12. The tapered portion of distal portion 24 of core wire 20 can be formed by a number of different techniques, such as centerless grinding, stamping, etc. Core wire 20 can be constructed of metals, metal alloys, polymers, metal-polymer composites, etc. In alternative embodiments, proximal portion 22 and distal portion 24 of core wire 20 can be constructed of different materials (e.g., materials having different moduli of elasticity, resulting in different flexibilities), in which case a connector (not shown) can join proximal portion 22 and distal portion 24 of core wire 20 via welding, brazing, adhesive, etc. The proximal portion 22 of the core wire 20 can be constructed of a relatively stiff material (e.g., straight 304v stainless steel) for pushability and torqueability, while the distal portion 24 of the core wire 20 can be constructed of a relatively soft material (e.g., straight superelastic or linear elastic alloy, e.g., nickel titanium alloy) for good lateral compliance and steerability.

[0051] In the illustrated embodiment, the guidewire body 12 has an isotropic primary bending stiffness (i.e., has substantially equal bending flexibility in all radial directions). For example, the distal section 24 of the core wire 20 may have a circular cross-section and the tubular support structure 26 may have a circumferentially uniform slot pattern. In alternative embodiments, the guidewire body 12 includes one or more structural features that result in an anisotropic primary bending stiffness. For example, at least a portion of the distal section 24 of the core wire 20 may be flat and / or the tubular support structure 26 may have a circumferentially non-uniform slot pattern. In this manner, the guidewire body 12 may have one or more preferred bending directions, or may bend more easily in some directions than others. In some embodiments, the preferred bending direction is oriented in only a single radial direction along one side of the guidewire body 12. For example, if the preferred bending direction is only to the left side of guidewire body 12 (as shown), guidewire body 12 may be more flexible when bending to the left than in other directions (e.g., including perpendicular or orthogonal to the preferred bending direction). In other embodiments, the preferred bending direction may be oriented in opposite radial directions along opposite faces of guidewire body 12. For example, if the preferred bending direction is to both the left and right sides of guidewire body 12 (as shown), guidewire body 12 may be more flexible when bending to the left or right than in other directions (e.g., including perpendicular or orthogonal to the preferred bending direction).

[0052] In one embodiment, guidewire body 12 further includes an outer polymer jacket (not shown) disposed over a portion of core wire 20 and / or tubular support structure 26, such that guidewire 10 and / or tubular support structure 26 define a generally smooth outer surface. However, in other embodiments, such an outer polymer jacket may be omitted from all or a portion of guidewire body 12, with core wire 20 and / or tubular support structure 26 forming the outer surface of guidewire body 12. In some embodiments, the outer surface of core wire 20 and / or tubular support structure 26 may be sandblasted, bead blasted, sodium bicarbonate blasted, electropolished, or the like. In some embodiments, at least a portion of the outer surface of the guidewire body 12 (e.g., the outer surface of the outer polymer jacket, if one is provided, or other surfaces of the core wire 20 and / or tubular support structure 26, if no outer polymer jacket is provided) has one or more coatings, such as, for example, an anti-thrombogenic coating that inhibits thrombus formation in vitro, an anti-bacterial coating, or a lubricious coating (e.g., a hydrophilic coating) that reduces static or dynamic friction between the guidewire body 12 and the patient's tissues as the guidewire body 12 advances through the vasculature or another catheter.

[0053] Although the tubular support structure 26 has been described as being incorporated into an elongated intravascular medical instrument in the form of a guidewire 10 for the purpose of dynamically adjusting the mechanical properties of the guidewire body 12, it should be understood that the tubular support structure 26 may be incorporated into any suitable elongated intravascular device for the purpose of dynamically adjusting the mechanical properties of the device.

[0054] For example, with reference to Figures 4-5, one embodiment of an intravascular catheter 50 is described. In the illustrated embodiment, the intravascular catheter 50 functions as a delivery catheter for delivering an intravascular implant 52 (e.g., a stent, stent graft, flow diverter, vascular occlusion device, vena cava filter, etc.) (shown in Figure 6) to a target site within a patient's vasculature; however, alternative embodiments of the intravascular catheter 50 may deliver other medical devices, such as, for example, another catheter, a guide member, a thrombus removal device, etc. Furthermore, other alternative embodiments of the intravascular catheter 50 may function as a diagnostic catheter or another type of therapeutic catheter (e.g., an access catheter, a balloon catheter, an atherectomy catheter, a drug delivery catheter, etc.).

[0055] The intravascular catheter 50 generally comprises an elongate sheath body 54 topographically divided between a proximal section 56 and a distal section 58, an inner sheath lumen 60 extending within the sheath body 54, a pusher member 62 slidably disposed within the sheath lumen 60, and a proximal adapter 64 attached to the free end of the proximal section 56 of the sheath body 54.

[0056] The diameter of the inner sheath lumen 60 can vary based on the medical procedure for which the intravascular catheter 50 is used and, in the illustrated embodiment, is sized to accommodate the intravascular implant 52. The diameter of the inner sheath lumen 60 can be substantially constant from the proximal portion 56 to the distal portion 58 of the sheath body 54, or it can taper from a first diameter at the proximal portion 56 of the sheath body 54 to a second, different diameter at the distal portion 58 of the sheath body 54. The inner sheath lumen 60 terminates in a distal port 66 at the end of the distal portion 58 of the sheath body 54.

[0057] The pusher member 62 carries the intravascular implant 52 and can be advanced distally within the inner sheath lumen 60 to deploy the intravascular implant 52 from the intravascular catheter 50 to a target site in the patient's vasculature. The proximal adapter 64 is secured to the proximal portion 56 of the intravascular catheter 50 by suitable means, such as adhesive, welding, or the like. The proximal adapter 64 includes a central bore 68 (shown in phantom) that communicates with the inner sheath lumen 60. The central bore 68 terminates in a proximal port 70 that allows the pusher member 62 and the intravascular implant 12 to be loaded into the intravascular catheter 50. The proximal adapter 64 further includes a side port 72 in fluid communication with the central bore 68 for introducing a fluid into the inner sheath lumen 60 to hydrate the pusher member 62 and the intravascular implant 12. In some embodiments, another structure (not shown) can be attached to the proximal portion 56 of the intravascular catheter 50 in addition to or instead of the proximal catheter hub 64. The intravascular catheter 50 further includes one or more radiopaque marker bands 74 (only one shown) disposed on the distal portion 58 of the sheath body 54 proximate the distal port 66 to enable medical imaging techniques (e.g., fluoroscopy) to identify the location of the distal tip of the intravascular catheter 50 within the patient's vasculature or relative to a partially or fully deployed intravascular implant 12. The radiopaque bands 74 may be constructed of a suitable radiopaque material, such as gold, platinum, palladium, tantalum, tungsten alloys, polymeric materials filled with radiopaque fillers, or the like.

[0058] The free end of the proximal section 56 of the sheath body 54 remains outside the patient and is accessible to an operator (e.g., a clinician or physician), while the remainder of the sheath body 54, including the distal section 58, is sized and dimensioned to reach remote locations in the patient's vasculature. The sheath body 54 has a length suitable for accessing a target tissue site within the patient from a vascular access point. The target tissue site varies depending on the medical procedure for which the intravascular catheter 50 is being used. For example, if the intravascular catheter 50 is used to access the vasculature in the patient's brain from a femoral artery access point in the patient's groin, the overall length of the sheath body 54 may be 125 cm to 200 cm. The outer diameter of the sheath body 54 may range from 3F to 10F. In one embodiment, the outer diameter of the sheath body 54 may be uniform along the length of the catheter body 18. In another embodiment, the outer diameter of the sheath body 54 may taper gradually or in steps from a first outer diameter at the proximal section 56 to a second outer diameter at the distal section 58 to facilitate navigation through tortuous vasculature. Although depicted as having a generally circular cross-sectional shape, it should be understood that the sheath body 54 may include other cross-sectional shapes or combinations of shapes, such as, for example, oval, rectangular, triangular, polygonal, etc.

[0059] The sheath body 54 has a linear configuration and is relatively straight at room and / or body temperature, but is flexible and bendable when subjected to an external force, allowing the sheath body 54 to be advanced through a patient's vasculature. The sheath body 54 has a transitional stiffness section, gradually decreasing from high stiffness in the proximal portion 56 to low stiffness along the distal portion 58, such that the sheath body 54 has sufficient pushability to advance through a patient's vasculature and torqueability to transmit rotational forces to the distal portion 58, allowing for easy transition between the linear configuration ( FIG. 4 ) and the curved configuration ( FIG. 5 ). The sheath body 54 may optionally include an intermediate portion (not shown) that gradually transitions from the relatively high bending stiffness of the proximal portion 56 to the relatively low bending stiffness of the distal portion 58.

[0060] 6, the sheath body 54 generally comprises a tubular support structure 76, an inner polymer liner 78 disposed within the tubular support structure 76, and an atraumatic distal tip member 80 attached to the distal tip of the tubular support structure 76. The sheath body 54 may further include a tie layer (not shown) that attaches the inner polymer liner 78 to the tubular support structure 76.

[0061] The tubular support structure 76 has a slot pattern designed to enhance the flexibility of the sheath body 54 while allowing for suitable torque transmission characteristics. In the illustrated embodiment, the slot pattern extends substantially the entire length and circumference of the tubular support structure 76; however, the slot pattern may alternatively extend along any length or circumference of the tubular support structure 76. While the tubular support structure 76 is illustrated as being disposed along both the proximal and distal portions 56, 58 of the sheath body 54, it should be understood that the tubular support structure 76 may be disposed anywhere on the sheath body 54, for example, only on the distal portion 58 of the sheath body 54, if dynamic adjustment of the mechanical properties (particularly bending stiffness and tensile strength) of the sheath body 54 is desired. Further details of the structure and function of tubular support structures that can be used as the tubular support structure 76 for the sheath body 54 are described in more detail below.

[0062] The inner polymer liner 78 is composed of a low-friction material (e.g., polytetrafluoroethylene (PTFE), expanded PTFE (ePTFE, e.g., unidirectional ePTFE or bidirectional ePTFE), fluoropolymer, perfluoroalkoxyalkane (PFA), fluorinated ethylene polyethylene (FEP), polyethylene (PE), or any combination thereof) that surrounds the inner sheath lumen 60. Thus, the inner polymer liner 78 can provide a lubricious inner surface to facilitate passage of the endovascular implant 52 through the inner sheath lumen 60.

[0063] In the illustrated embodiment, the sheath body 54 has an isotropic primary bending stiffness (i.e., substantially equal bending flexibility in all radial directions). For example, the tubular support structure 76 may have a uniform slot pattern in the circumferential direction. In alternative embodiments, the sheath body 54 includes one or more structural features that achieve an anisotropic primary bending stiffness. As such, the sheath body 54 may have more than one preferred bending direction, or may bend more easily in some directions than in others. In some embodiments, the preferred bending direction is oriented in only a single radial direction along one side of the sheath body 54. For example, if the preferred bending direction is oriented only toward the left side of the sheath body 54 (as shown), the sheath body 54 may be more flexible when bending to the left than in other directions (e.g., including directions perpendicular or orthogonal to the preferred bending direction). In other embodiments, the preferred bending direction may be oriented in the opposite radial direction along the opposite face of the sheath body 54. For example, if preferred bending directions are to the left and right of the sheath body 54 (as shown), the sheath body 54 may be more flexible in bending to the left and right than in other directions (including, for example, directions perpendicular or orthogonal to the preferred bending directions).

[0064] In one embodiment, the sheath body 54 further includes an outer polymer jacket (not shown) disposed over all or a portion of the tubular support structure 76, thereby defining a generally smooth outer surface of the tubular support structure 76. However, in other embodiments, such an outer polymer jacket may be omitted from some or all of the sheath body 54, with the tubular support structure 76 forming the outer surface of the sheath body 54. If an outer polymer jacket is provided on the proximal portion 56 of the sheath body 54, the sheath body 54 may further include a reinforcing layer, such as a braided or coiled layer, to enhance the pushability of the sheath body 54. In some embodiments, the outer surface of the tubular support structure 76 may be sandblasted, bead blasted, sodium bicarbonate blasted, electropolished, or the like. In some embodiments, at least a portion of the outer surface of the sheath body 54 (e.g., the outer surface of the outer polymer jacket, if present, or other surfaces of the tubular support structure 76, if no outer polymer jacket is present) has one or more coatings, such as, for example, an anti-thrombogenic coating to inhibit thrombus formation in vitro, an anti-bacterial coating, or a lubricious coating (e.g., a hydrophilic coating) to reduce static or dynamic friction between the sheath body 54 and the patient's tissue as the sheath body 54 is advanced over a guidewire through the vasculature or guide sheath. The distal tip member 80 may be in the form of a polymer tip disposed at the distal end of the core wire 20.

[0065] Next, with reference to Figures 7 to 10, we will describe one embodiment of a tubular support structure 100 that can be used for the tubular support structure 26 of the intravascular guidewire 10 shown in Figures 1 to 3 or the tubular support structure 76 of the intravascular catheter 50 shown in Figures 4 to 6.

[0066] The tubular support structure 100 generally comprises an elongated tubular body 102 having a longitudinal axis 104, a patterned framework 106 formed in the tubular body 102, an inner lumen 108 disposed axially along the longitudinal axis 104 of the tubular body 102, and a plurality of mechanical property modulating elements 110 spaced axially along the patterned framework 106 and spaced circumferentially around the patterned framework 106.

[0067] The tubular body 102 can be constructed from any of a variety of suitable materials, including materials that are rigid but have some flexibility when used to form extremely thin structures such as the walls of the tubular body 102. In the illustrated embodiment, the tubular body 102 takes the form of a hypotube constructed from a metal or metal alloy (e.g., 304 stainless steel, 316 stainless steel, 316L stainless steel, nickel-chromium (NiCr) steel, nickel-titanium alloys (e.g., Nitinol), cobalt / chromium), or the like. Alternatively, the tubular support structure 100 may be constructed from a rigid polymer (e.g., polyetheretherketone (PEEK)). The dimensions of the tubular body 102 can be suited to one or more desired uses of an elongated medical device, such as the guidewire 10 of FIGS. 1-3 or the intravascular catheter 50 of FIGS. 4-6. By way of example, the outer diameter of the tubular body 44 can range from 0.005 to 0.150 inches. The inner diameter of the tubular body 44 (ie, the diameter of the lumen 108) can be, for example, in the range of 0.002 to 0.145 inches.

[0068] The patterned framework 106 enhances the flexibility of the tubular support structure 100, allowing it to deflect laterally in a bending direction 112 in response to a bending force from a relaxed (in this case, straight) configuration ( FIG. 7 ) to a curved configuration ( FIG. 8 ) within a lateral deflection range 114 (α). While the relaxed configuration of the tubular support structure 100 is illustrated as a straight configuration, in an alternative embodiment, the tubular support structure 100 may be pre-formed so that its relaxed configuration is a curved configuration. In this alternative, the tubular support structure 100 may deflect in a bending direction within a lateral deflection range from the relaxed, curved configuration to an increased curved configuration (i.e., having a radius of curvature smaller than that of the relaxed, curved configuration) in response to a bending force. In any event, with the increased flexibility of the tubular support structure 100, the patterned framework 106 may also deflect laterally in response to a tensile force 116 within an axial extension range 118 (α). Δ 7) to an increased length l1 (FIG. 9).

[0069] The patterned framework 106 may include any combination of openings 122 and members 124 that provide a desired primary (or initial) bending stiffness for the tubular support structure 100. For example, as shown in FIG. 20 , the tubular support structure 100 has an exemplary primary bending stiffness 200 (shown by the dashed line), which defines a bending force (vertical axis) that varies linearly with the amount of lateral deflection (horizontal axis) of the patterned framework 106 (or is inversely related to the amount of radius of curvature). Thus, as can be seen from FIG. 20 , the primary bending stiffness 200 is generally uniform in the absence of modulation. The primary bending stiffness 200 is preferably finite (i.e., the primary bending stiffness 200 is preferably substantially greater than zero). For example, the primary bending stiffness 200 may be greater than 0.00001 in 2 As described in more detail below, the modulation element 110 modulates the patterned framework 106 such that the tubular support structure 100 has one or more secondary bending stiffnesses 202, and thus, incremental bending stiffnesses.

[0070] In the illustrated embodiment, the tubular support structure 100 has a radially isotropic primary bending stiffness 200. For purposes of this specification, a tubular support structure 100 has a radially isotropic primary bending stiffness 200 if the primary bending stiffness 200 is the same in at least four equally spaced radial directions. The tubular support structure 100 can achieve an isotropic primary bending stiffness 200 by circumferentially repeating the pattern of openings 122 and members 124 around the entire patterned frame structure 106. In an alternative embodiment, the tubular support structure 100 has an anisotropic primary bending stiffness 200. For example, the primary bending stiffness 200 of the tubular support structure 100 can be lower in a first two diametrically opposed radial directions (e.g., radial directions 120a, 120c) than in a second two diametrically opposed radial directions (e.g., radial directions 120b, 120d) that are rotated 90 degrees from the first two diametrically opposed radial directions (e.g., radial directions 120a-120b).

[0071] Importantly, the modulation element 110 is configured to modulate, and particularly gradually increase, the bending stiffness of the tubular support structure 100 in response to laterally deflecting the tubular support structure 100 in at least one bending direction, such that the primary bending stiffness 200 of the tubular support structure 100 transitions to one or more higher secondary bending stiffnesses 202, as illustrated in FIG. 20 . In particular, the modulation of the bending stiffness of the tubular support structure 100 in response to laterally deflecting the tubular support structure 100 in a particular bending direction generates one or more inflection points 204 that define a transition between the primary bending stiffness 200 in a primary lateral deflection range and one or more secondary bending stiffnesses 202, in this case two secondary bending stiffnesses 202 a, 202 b, in a secondary lateral deflection range that is greater than the primary lateral deflection range. At each inflection point 204, the bending stiffness of the tubular support structure 100 for a particular bending direction increases. Thus, the primary bending stiffness 200 of the tubular support structure 100 does not continue unmodulated (as shown by the dashed line), but rather transitions to a secondary bending stiffness 202, in this case to bending stiffness 202a and then to bending stiffness 202b. It should be understood that the primary bending stiffness 200 of the tubular support structure 100 may transition to any number of secondary bending stiffnesses 202, including only one secondary bending stiffness 202, or two or more secondary bending stiffnesses 202.

[0072] The bending stiffness of the tubular support structure 100 may be increased by less than 500%, preferably less than 200%, from an initial bending stiffness (in this case, the primary bending stiffness 200) to a maximum bending stiffness (in this case, the maximum secondary bending stiffness 202) so as to maintain compliance of the tubular support structure 100 through a patient's vasculature. Furthermore, abruptly changing the bending stiffness to a very high value, rather than adjusting (i.e., gradually increasing), can significantly impair the maneuverability of the elongated intravascular medical device, making it too stiff to safely advance through a patient's vasculature. It should be understood that the bending stiffness of the tubular support structure 100 is reversible, and as the tubular support structure 100 returns to its straight configuration, the secondary bending stiffness 202b returns to the secondary bending stiffness 202a, and then back to the primary bending stiffness 200.

[0073] In the illustrated embodiment, modulation elements 110 are arranged in sets 110a-110d (best shown in FIG. 10), in this case four circumferentially aligned sets (i.e., rows), with each modulation element 110 in rows 110a-110d spaced axially from one another along patterned frame structure 106, and modulation element rows 110a-110d spaced circumferentially from one another by 90°. In this manner, the bending stiffness of tubular support structure 100 can be adjusted in four different radial directions, spaced 90° apart.

[0074] In the illustrated embodiment, only a single modulation element row (i.e., the modulation element row at the outer edge of the curvature (in this case, modulation element row 110a shown in FIG. 8)) is responsible for modulating the bending stiffness of the tubular support structure 100 when deflected laterally in the direction of the respective modulation element row (i.e., the single modulation element row is active and the other three modulation element rows are inactive).

[0075] In an alternative embodiment, the single row of modulation elements responsible for modulating the bending stiffness of the tubular support structure 100 is opposite the direction in which the tubular support structure 100 is laterally deflected (i.e., the row of modulation elements at the inner edge of the curve (in this case, row of modulation elements 110c shown in FIG. 8)). In another alternative embodiment, two diametrically opposed rows of modulation elements (i.e., the rows of modulation elements at the outer and inner edges of the curve (in this case, rows of modulation elements 110a and 110c shown in FIG. 8)) together are responsible for modulating the bending stiffness of the tubular support structure 100 when the tubular support structure 100 is laterally deflected in the direction of one of the two respective rows of modulation elements. It should be understood that when the tubular support structure 100 is laterally deflected in a direction between an adjacent pair of rows of modulation elements (e.g., row of modulation elements 110a and row of modulation elements 110b), each pair of rows of modulation elements can contribute to modulating the primary bending stiffness of the tubular support structure 100.

[0076] Because modulation element arrays 110a-110d are circumferentially spaced 90° from one another around patterned frame structure 106, it should be understood that, assuming modulation element arrays 110a-110d are identical, modulation elements 110 may be configured to increase the bending stiffness of tubular support structure 100 from an initial radially isotropic primary bending stiffness 200 to one or more radially isotropic secondary bending stiffnesses 202. Thus, modulation element arrays 110a-110d substantially uniformly modulate the bending stiffness of tubular support structure 100 circumferentially such that tubular support structure 100 has a radially isotropic secondary bending stiffness 202. For purposes herein, tubular support structure 100 has a radially isotropic secondary bending stiffness 202 if the secondary bending stiffness 202 is the same in at least four equally spaced radial directions (e.g., four equally spaced radial directions 120a-120d spaced 90° apart as illustrated in FIG. 10 ). As a result, the secondary bending stiffness 202 may have four 90° circumferential regions 208 centered on the four modulation element rows 110a to 110d, respectively, as shown in FIG.

[0077] While Figures 7-10 illustrate the modulation elements 110 as being arranged in circumferentially aligned sets on the patterned framework structure 106, in an alternative embodiment of the tubular support structure 100', as shown in Figure 12, the modulation elements 110 may be arranged in four circumferentially offset sets on the patterned framework structure 106 (only sets 110a'-110c' are shown). By axially offsetting the modulation elements 110 on the patterned framework structure 106, the secondary bending stiffness 202 of the tubular support structure 100' may be more radially isotropic. That is, by circumferentially spacing the modulation elements within each set 110' of modulation elements on the patterned framework structure 106, the preferential bending direction of the tubular support structure 100' within the secondary lateral deflection range is smoothed out, which would otherwise result from the circumferentially aligned rows of modulation elements or tolerances in the manufacturing process of the tubular support structure 100'.

[0078] In an alternative embodiment, the modulation element 110 may be configured to increase the bending stiffness of the tubular support structure 100 from an initial radially isotropic first order bending stiffness to a radially anisotropic second order bending stiffness. For example, as shown in FIGS. 13-14, an alternative embodiment of a tubular support structure 100'' may have only two diametrically opposed rows of modulation elements 110a, 110c disposed on a patterned frame structure 106. In this manner, the tubular support structure 100'' has a secondary bending stiffness 202 when deflected laterally in a bending direction toward either of the opposing rows of modulation elements 110a, 110c, and a reduced or zero secondary bending stiffness 202 when deflected laterally 90° from the opposing rows of modulation elements 110a, 110c. 15, the secondary bending stiffness 202 has two diametrically opposed, relatively smaller 90° circumferential regions 208a centered at circumferential locations in the patterned frame structure 106 where no modulation element arrays are present (i.e., modulation element arrays 110b, 110d are omitted), and two diametrically opposed, relatively smaller 90° circumferential regions 208b centered at circumferential locations in the patterned frame structure 106 where modulation element arrays are present (i.e., modulation element arrays 110a, 110c are present). The minimum magnitude of the relatively lower circumferential regions 208a of the secondary bending stiffness 202 is equal to the magnitude of the primary bending stiffness 200.

[0079] As another example, as shown in FIGS. 16-17, another alternative embodiment of the tubular support structure 100''' may include a single array of modulation elements 110b disposed on the patterned frame structure 106, such that the tubular support structure 100''' has a secondary bending stiffness 202 of at least one when deflected laterally in a bending direction toward (or away from) the array of modulation elements 110b, and a reduced or zero secondary bending stiffness 202 when deflected laterally away from (or towards) the array of modulation elements 110b. 18, the secondary bending stiffness 202 may have one 270° circumferential region 208a of relatively low magnitude centered around a circumferential location in the patterned frame structure 106 where no modulation element array is present (i.e., modulation element array 110b is omitted), and one 90° circumferential region 208b of relatively low magnitude centered around a circumferential location in the patterned frame structure 106 where a modulation element array is present (i.e., modulation element array 110b is present). The minimum magnitude of the relatively low circumferential region 208a of the secondary bending stiffness 202 is equal to the magnitude of the primary bending stiffness 200.

[0080] While the radially isotropic primary bending stiffness 200 of the patterned frame structure 106 of the tubular support structures 100'' and 100'''' shown in Figures 13-14 and 16-17 is configured to increase to a radially anisotropic secondary bending stiffness 202 by omitting one or more rows of modulation elements 110, the tubular support structure 100 shown in Figures 7-10 can be designed to increase the radially isotropic primary bending stiffness 200 to a radially anisotropic bending stiffness 202 with all of the rows of modulation elements 110 evenly spaced circumferentially around the patterned frame structure. For example, secondary bending stiffness 202 may have two diametrically opposed 90° circumferential regions 208a of relatively low stiffness centered on modulation element rows 110b, 110d and two diametrically opposed 90° circumferential regions 208b of relatively low stiffness centered on modulation element rows 110a, 110c, as shown in Figure 19. The minimum magnitude of relatively low circumferential regions 208a of secondary bending stiffness 202 is greater than the magnitude of primary bending stiffness 200.

[0081] To impart radial anisotropy to the secondary bending stiffness 202 of the tubular support structure 100, at least two of the rows of modulation elements 110 are designed to modulate the secondary bending stiffness 202 in different manners, thereby resulting in each of the secondary bending stiffnesses 202 being radially anisotropic. For example, all of the modulation elements 110 in one of the rows 110a-110d may modulate the bending stiffness of the tubular support structure 100 for a particular lateral deflection in one radial direction, while none or only some of the modulation elements 110 in a different one of the rows 110a-110d may modulate the bending stiffness of the tubular support structure 100 for the same lateral deflection in a different radial direction (e.g., the lengths of the mechanical adjustment elements 110 in different rows 110a-110d may be different from each other). 19 may be dynamic in nature, in that its profile changes as a function of the magnitude of lateral deflection of the tubular support structure 100. Alternatively, all of the modulation element arrays 110a-110d may modulate the bending stiffness of the tubular support structure 100 for the same particular lateral deflection in all radial directions. However, at least two of the modulation element arrays 110a-110d may modulate the bending stiffness of the tubular support structure 100 to different degrees (e.g., pairs of extensions 172 associated with different ones of the modulation element arrays 110a-110d may have different lengths).

[0082] Similar to bending stiffness, the combination of openings 122 and members 124 provides a desired primary (or initial) tensile stiffness for tubular support structure 100. For example, as shown in FIG. 21 , tubular support structure 100 has an exemplary primary tensile stiffness 250 that defines a tensile stiffness (vertical axis) that varies linearly in direct proportion to the amount of axial stretch (horizontal axis) of tubular support structure 100. Thus, as can be seen from FIG. 21 , primary tensile stiffness 250 is generally uniform without modulation. Primary tensile stiffness 250 is preferably finite (i.e., primary tensile stiffness 250 is preferably substantially greater than zero). For example, primary tensile stiffness 250 may be greater than 0.05 pounds.

[0083] Importantly, the modulation element 110 is also configured to modulate, and in particular gradually increase, the tensile stiffness 250 of the tubular support structure 100 in response to axial stretching of the tubular support structure 100, such that the primary tensile stiffness 250 of the tubular support structure 100 transitions to one or more higher secondary tensile stiffnesses 252, as shown in FIG. 21. In particular, just as modulation of the bending stiffness of the tubular support structure 100 in response to laterally deflecting the tubular support structure 100 in a particular bending direction creates one or more inflection points 204 that define a transition between the primary bending stiffness 200 and the secondary bending stiffness 202, as shown in Figure 20, modulation of the tensile stiffness of the tubular support structure 100 in response to axial stretching of the tubular support structure 100 creates one or more inflection points 254 that define a transition between the primary tensile stiffness 250 in the primary axial stretch range and one or more secondary tensile stiffnesses 252, in this case two secondary tensile stiffnesses 252a, 252b, in a secondary axial stretch range that is greater than the primary axial stretch range. At each inflection point 254, the tensile stiffness of the tubular support structure 100 increases. Thus, rather than remaining unmodulated (as shown by the dashed line), the primary tensile stiffness 250 of the tubular support structure 100 transitions to a secondary tensile stiffness 252, in this case tensile stiffness 252a, and then to tensile stiffness 252b. Thus, after an initial axial extension (during which the tubular support structure 100 has the primary tensile stiffness 250), the modulation element 110 is tensile loaded in pure tension (during which the tubular support structure 100 has the secondary tensile stiffness 252). It should be understood that the primary tensile stiffness 250 of the tubular support structure 100 may transition to any number of secondary tensile stiffnesses 252, including only one secondary tensile stiffness 252, or two or more secondary tensile stiffnesses 252. Importantly, by increasing the tensile stiffness of the tubular support structure 100, the adjustment element 110 effectively increases the tensile strength of the tubular support structure 100 beyond the tensile strength of a typical slotted tubular support structure having the same lateral bending stiffness as the primary bending stiffness 200 of the tubular support structure 100.

[0084] The tensile stiffness of the tubular support structure 100 can be increased by 50% or more, preferably 100% or more, from an initial tensile stiffness (in this case, the primary tensile stiffness 250) to a maximum tensile stiffness (in this case, the maximum secondary tensile stiffness 252) so that the tubular support structure 100 will not plastically deform even under large tensile forces. It should be understood that the tensile stiffness of the tubular support structure 100 is reversible, such that as the tubular support structure 100 relaxes axially, the secondary tensile stiffness 252b returns to the secondary tensile stiffness 252a and then back to the primary tensile stiffness 250.

[0085] 22A and 22B, each modulation element 110 takes the form of a floating tab having a cantilevered end 126 fixed to the patterned frame structure 106 (particularly, one or more of the members 124) and a free end 128 configured to move relative to the patterned frame structure 106 (e.g., in direction 129) when the patterned frame structure 106 is laterally deflected or axially stretched. In particular, as shown in FIG. 22A, the cantilevered end 126 of the floating tab 110 may be fixed to member 124a of the patterned frame structure 106, while the free end 128 of the floating tab 110 floats relative to members 124b-124f. As shown in FIG. 22B, when the tubular support structure 100 is laterally deflected or axially stretched, the spacing between the members 124 increases. Cantilevered end 126 of floating tab 110 remains fixed to member 124a and therefore moves with member 124a, while members 124b-124f move relative to free end 128 of floating tab 110. As patterned framework structure 106 is further laterally deflected or axially stretched, free end 128 of floating tab 110 engages one or more of members 124 (e.g., members 124b-124d), at which point free end 128 of floating tab 110 moves with the member 124 with which it is engaged, thereby modulating patterned framework structure 106 and, in particular, increasing the bending and tensile stiffness of tubular support structure 100. A particular floating tab 110 may be considered active or actuated when its free end 116 is engaged with the patterned frame structure 106, and may be considered inactive or non-actuated when its free end 116 is moving relative to or otherwise not engaged with the patterned frame structure 106. Further details regarding one embodiment of the patterned frame structure 106 and floating tab 110 are provided below.

[0086] 20. Actuation of the floating tabs 110 corresponds to inflection points 204 shown in FIG. 20. When the tubular support structure 100 initially deflects laterally within the primary lateral deflection range, all of the floating tabs 110 are inactive and the bending stiffness of the tubular support structure 100 is not modulated, and therefore, within this primary lateral deflection range, it has a primary bending stiffness 200. However, as the tubular support structure 100 subsequently deflects laterally within the secondary lateral deflection range, one or more of the floating tabs 110 are actuated, and the bending stiffness of the tubular support structure 100 is modulated (i.e., increased), and therefore, it has one or more secondary bending stiffnesses 202 within the secondary lateral deflection range that are greater than the primary bending stiffness 200.

[0087] If the tubular support structure 100 has only one secondary bending stiffness 202 for each bending direction, all of the floating tabs 110 (e.g., one of the rows of modulation elements 110a-110d) responsible for modulating the bending stiffness of the tubular support structure 100 for each bending direction will be active as the tubular support structure 100 deflects laterally from the primary lateral deflection range to the secondary lateral deflection range. However, if the tubular support structure 100 has multiple secondary bending stiffnesses 202 for each bending direction, different sets of floating tabs 110 (e.g., two sets of floating tabs 110 in one of the rows of modulation elements 110a-110d) responsible for modulating the bending stiffness of the tubular support structure 100 will be progressively active as the bending stiffness of the tubular support structure 100 deflects laterally through the secondary lateral deflection range. That is, a first set of floating tabs 110 becomes active when the bending stiffness of the tubular support structure 100 deflects laterally a first degree within the secondary lateral deflection range, and then a second set of floating tabs 110 becomes active (while the first set of floating tabs 110 remain active) when the bending stiffness of the tubular support structure 100 deflects laterally further to a second, higher degree within the secondary lateral deflection range.

[0088] It should be appreciated that when the tubular support structure 100 is laterally deflected from the secondary lateral deflection range back to the primary lateral deflection range, all of the floating tabs 110 become inactive and the bending stiffness of the tubular support structure 100 is not modulated, and therefore it again has the primary bending stiffness 200 within this primary lateral deflection range.

[0089] 21. Actuation of the floating tabs 110 also corresponds to inflection point 254 shown in FIG. 21. When the tubular support structure 100 is initially axially stretched within the primary lateral deflection range, all of the floating tabs 110 are inactive and the tensile stiffness of the tubular support structure 100 is not modulated, and therefore, within this primary lateral deflection range, it has a primary tensile stiffness 250. However, when the tubular support structure 100 is subsequently axially stretched within a secondary axial extension range, one or more of the floating tabs 110 become active and the tensile stiffness of the tubular support structure 100 is modulated (i.e., increased), resulting in one or more secondary tensile stiffnesses 252 within the secondary axial extension range that are greater than the primary tensile stiffness 250.

[0090] If the tubular support structure 100 has only one secondary tensile stiffness 252, all of the floating tabs 110 will be active as the tubular support structure 100 is axially stretched from the primary axial stretch range to the secondary axial stretch range. However, if the tubular support structure 100 has multiple secondary tensile stiffnesses 252, different sets of the floating tabs 110 (e.g., one or more floating tabs 110 in each modulation element row 110a-110d comprising a set of circumferentially arranged floating tabs 110) will be progressively active as the tubular support structure 100 is axially stretched through the secondary axial stretch ranges. That is, when the tubular support structure 100 is axially stretched a first degree within the secondary axial stretch range, a first set of floating tabs 110 (e.g., a first set of circumferentially arranged floating tabs 110) becomes active, and then when the tubular support structure 100 is further axially stretched a second, higher degree within the secondary axial stretch range, a second set of floating tabs 110 becomes active (while the first set of floating tabs 110 remain active).

[0091] It should be appreciated that as the tubular support structure 100 axially relaxes from the secondary axial extension range to the primary axial extension range, all of the floating tabs 110 become inactive and the tensile stiffness of the tubular support structure 100 is not modulated, and therefore, within this primary axial extension range, it again has the primary tensile stiffness 250. Notably, in the illustrated embodiment, the sequence of actuation of the floating tabs 110 to modulate the tensile stiffness of the tubular support structure 100 is the same as the sequence of actuation of the floating tabs 110 to modulate the bending stiffness of the tubular support structure 100. In this manner, the number of inflection points 254 and secondary tensile stiffnesses 252 tracks the number of inflection points 204 and secondary tensile stiffnesses 202 of the patterned frame structure 106.

[0092] 23-27, a specific embodiment of the tubular support structure 150a will be described. While the tubular support structure 150a is shown as being of a relatively short length for purposes of illustration, it should be understood that the tubular support structure 150a may have any suitable length, including extending the entire length of a catheter or guidewire.

[0093] The tubular support structure 150a generally comprises an elongated tubular body 152 having a longitudinal axis 154, a patterned framework 156a formed on the tubular body 152, an inner lumen 158 disposed axially along the longitudinal axis 154 of the tubular body 152, and a plurality of mechanical property modulating elements 160 (in this case, floating tabs 160) spaced axially along the patterned framework 156 and spaced circumferentially around the patterned framework 156.

[0094] The patterned framework 156, along with the floating tabs 160, may be formed on the tubular body 152 using any suitable process, including methods such as laser cutting, etching, waterjet cutting, electrical discharge machining, grinding, milling, casting, molding, etc. Although the patterned framework 156a is shown extending along substantially the entire length and circumference of the tubular body 152, the patterned framework 156a may extend along a portion of the length of the tubular body 152 that includes only a proximal portion of the tubular body 152, or a portion of the length of the tubular body 152 that includes only a distal portion of the tubular body 152, or a portion of the circumference of the tubular body 152, e.g., only 180° or 90° (if it is desired that the patterned framework 156a have a radially anisotropic primary bending stiffness).

[0095] The patterned framework 156a has a plurality of bending flexibility-enhancing apertures 162 configured to reduce the bending stiffness of the patterned framework 156a to create a primary bending stiffness in at least one bending direction. In the illustrated embodiment, the apertures 162 are formed completely through the tubular body 152 such that the lumen 158 of the tubular support structure 150a is exposed through the apertures 162, however, in alternative embodiments, the apertures 162 are formed partially through the tubular body 152 such that the lumen 158 of the tubular support structure 150a is not exposed through the apertures 162.

[0096] In the illustrated embodiment, the apertures 162 are arranged in sets 162a-162h, and in this case are arranged in circumferentially aligned sets (i.e., rows) that are uniformly spaced apart circumferentially around the patterned frame structure 156a, with the apertures 162 in each of the rows 162a-162h being uniformly spaced apart axially along the patterned frame structure 156a. In the illustrated embodiment, the apertures 162 are arranged in eight rows 162a-162h that are circumferentially spaced 45° apart from one another, with each row of apertures 162a-162h having four apertures 162. It should be understood that the apertures 162 may be arranged in any suitable number of rows, and that each row of apertures 162a-162h may have any suitable number of apertures 162.

[0097] In the illustrated embodiment, the tubular support structure 150a has a radially isotropic primary bending stiffness, however, in alternative embodiments, the tubular support structure 150a may have a radially anisotropic primary bending stiffness. For example, in alternative embodiments, the tubular support structure 150a may have only two diametrically opposed rows of apertures (e.g., rows 162a and 162e), in which case the magnitude of the primary bending stiffness of the patterned frame structure 156a is equal when deflected laterally in a bending direction toward either row 162a or 162e, and increases when deflected laterally 90° from the opposing row 162a. As another example, the patterned framework 156a may have a single row of apertures (e.g., row 162c), in which case the degree of primary bending stiffness of the tubular support structure 150a when deflected laterally in a bending direction toward the single row of apertures 162c is less than the degree of primary bending stiffness of the tubular support structure 150a when deflected laterally in a bending direction away from the single row of apertures 162c. In other embodiments, the patterned framework 156a may have the same number of rows of apertures 162 as shown in FIG. 23, but some of the rows of apertures 162 lack floating tabs 160, stem elements 172, or extensions 172, such that the stiffness may not change due to the interaction of these elements when the tubular support structure 150a is deflected laterally.

[0098] In the illustrated embodiment, each opening 162 includes a transverse slot 164, a retainer opening 166, and an axial channel 168. The transverse slots 164 are coextensive with the retainer openings 166, and in particular, the axial channel 168 connects the transverse slots 164 and the retainer openings 166. While the slots 164 are illustrated as generally rectangular, the slots 164 may have other elongated shapes, such as oval or elliptical. Furthermore, in alternative embodiments, slits (not shown) may be formed in the tubular body 152 rather than slots 164. In the illustrated embodiment, each retainer opening 166 is rectangular, but in alternative embodiments, the retainer openings 166 may have different geometric shapes. However, the retainer openings 166 are preferably shaped to facilitate axial movement of the floating tabs 160 therethrough, as described in more detail below.

[0099] In the illustrated embodiment, each of the aperture rows 162a-162h is axially offset from its two nearest adjacent aperture rows such that the horizontal slots 164 of each aperture row are alternated with the horizontal slots 164 of the aperture rows on either side of each aperture row 162a-162h (e.g., the horizontal slots 164 of aperture row 162b shown in FIG. 23 are alternated with the horizontal slots 164 of aperture rows 162a, 162c, or the horizontal slots 164 of aperture row 162g shown in FIG. 24 are alternated with the horizontal slots 164 of aperture rows 162f, 162h). Furthermore, the horizontal slots 164 of each of the opening rows 162a-162h are circumferentially aligned with the retainer openings 166 of the two most adjacent opening rows (e.g., the horizontal slots 164 of opening row 162b shown in FIG. 23 are circumferentially aligned with the retainer openings 166 of opening rows 162a and 162c, or the horizontal slots 164 of opening row 162g shown in FIG. 24 are circumferentially aligned with the retainer openings 166 of opening rows 162f and 162h).

[0100] Substantial transverse members 170 are formed between the alternating transverse slots 164 of adjacent opening rows 162a-162h, such that circumferentially aligned sets (i.e., rows) of transverse members 170 are circumferentially spaced about patterned frame structure 156, with the transverse members 170 in each row of transverse members 170 being axially spaced from one another along patterned frame structure 156. Each of transverse members 170 extends between the retainer openings 166 and axial channels 168 of the two most adjacent opening rows, with the ends of transverse members 170 adjacent to their respective axial channels 168 forming extensions 172 that abut their respective axial channels 168. As described in further detail below, each floating tab 160 is mechanically coupled to at least one of the lateral members 170 (in this case, a pair of circumferentially aligned lateral members 170) such that flexing of the lateral members 170 in response to laterally deflecting or axially stretching the patterned frame structure 156 causes the floating tabs 160 to move axially. The extensions 172 serve as abutments for the floating tabs 160 associated with the retainer openings 166 communicating with the respective axial channels 168. In particular, the extensions 172 of each pair of two adjacent circumferentially aligned lateral members 170 define an axial channel 168 and serve as abutments for the floating tabs 160 associated with the retainer openings 166 communicating with the respective axial channels 168. The pair of extensions 172 are configured to flex laterally when the floating tabs 160 engage therewith, thereby reducing the secondary bending stiffness of the tubular support structure 150a.

[0101] Axial connecting members 174 rigidly connect the transverse members 170 in each row of transverse members 170. In particular, each connecting member 174 rigidly connects the ends of two axially adjacent transverse members 170 in alternating directions, such that the transverse members 170 and connecting members 174 in each row form a zigzag pattern extending axially along the patterned frame structure 156.

[0102] Although the transverse slots 164 and transverse members 170 are illustrated as extending perpendicular to the longitudinal axis 154 of the tubular body 152 and being completely transverse, the transverse slots 164 and transverse members 170 need not be completely transverse. For example, the slots 164 and / or members 170 may be substantially lateral, extending within an angular range of ±10° from perpendicular to the longitudinal axis 154 of the tubular body 152. Furthermore, although the channels 168 and connecting members 174 are illustrated as extending parallel to the longitudinal axis 154 of the tubular body 152 and axially along the patterned framework 156a, the channels 168 and connecting members 174 need not be completely axial. For example, the channels 168 and connecting members 174 may be substantially axial, extending within an angular range of ±10° from the longitudinal axis 154 of the tubular body 152. It should also be understood that the slots 164, transverse members 170, channels 168, and / or connecting members 174 may be disposed obliquely relative to the longitudinal axis 154 of the tubular body 152, for example, at 45 degrees relative to the longitudinal axis 154 of the tubular body 152.

[0103] In the illustrated embodiment, the apertures 162 maintain the same shape throughout the thickness of the tubular body 152, however, in alternative embodiments, the shape of the apertures 162 may vary across the thickness of the tubular body 152. It should be further understood that numerous other shapes are contemplated for the apertures 162, including circles and polygons such as triangles, squares, rectangles, parallelograms, diamonds, trapezoids, etc. The apertures 162 are positioned in the patterned framework 156 so that they do not overlap one another, however, alternatively, at least a portion of the apertures 162 may overlap one another.

[0104] While the patterned framework 156a is illustrated as being regular (i.e., having a predictably repeating pattern), the patterned framework 156a may also be irregular (i.e., having an unpredictably repeating pattern). Additionally, while the slots 164 and members 170, 174 are illustrated as being equal in size, the slots 164 and members 170, 174 may be sized differently from one another. Additionally, while the patterned framework 156a is uniform along the length of the tubular body 152, the size, shape, and / or angle of the openings 162 and members 170, 174 may vary along the length of the tubular body 152 to vary the primary bending stiffness of the patterned framework 156a along the length of the tubular body 152.

[0105] The floating tabs 160 modulate (by increasing) the bending and tensile stiffness of the patterned framework structure 156. In the illustrated embodiment, the floating tabs 160 are integrally formed with the patterned framework structure 156. Similar to the modulating element 110 shown in FIGS. 7-10, the floating tabs 160 in the embodiment illustrated in FIGS. 23-27 are arranged in sets 160a-160h, in this case as uniformly spaced sets (i.e., rows) circumferentially around the patterned framework structure 156a, with the floating tabs 160 in each row 160a-160h uniformly spaced axially along the patterned framework structure 156a. In the illustrated embodiment, the floating tabs 160 are arranged in eight rows 160a-160h circumferentially spaced 45° from one another, with each row of floating tabs 160a-160h having four floating tabs 160. Thus, the bending stiffness of tubular support structure 150a can be modulated in eight different radial directions spaced 45 degrees apart. It should be understood that floating tabs 160 can be arranged in any suitable number of rows, and that each of floating tab rows 160a-160h can have any suitable number of floating tabs 160.

[0106] In this embodiment, the rows of floating tabs 160a-160h are identical, and thus the floating tabs 160 are configured to increase the bending stiffness of the tubular support structure 150a from an initial radially isotropic, first-order bending stiffness to one or more radially isotropic, second-order bending stiffnesses. In alternative embodiments, the floating tabs 160 may be configured to increase the bending stiffness of the tubular support structure 150a from an initial radially isotropic, first-order bending stiffness to one or more radially anisotropic, second-order bending stiffnesses. For example, the rows of floating tabs 160a-160h may not be identical, or the tubular support structure 150a may have only two diametrically opposed rows of floating tabs 160 arranged on the patterned framework structure 156 (e.g., similar to the arrangement of the modulation elements 110 shown in FIGS. 12-13), or may have a single row of floating tabs 160 arranged on the patterned framework structure 156 (e.g., similar to the arrangement of the modulation elements 110 shown in FIGS. 15-16). Although the floating tabs 160 are shown in Figures 23-27 as being arranged in circumferentially aligned sets, an alternative embodiment of the tubular support structure 150b may be arranged as eight circumferentially offset, circumferentially displaced sets (only sets 160a'-160d' are shown), as shown in Figure 29, with the patterned frame structure 156b having the floating tabs 160 arranged in eight circumferentially offset, circumferentially displaced sets (only sets 162a'-162d' are shown), similar to the arrangement of the modulation element 110 shown in Figure 12.

[0107] It should be understood that the floating tabs 160 may be arranged in any suitable number of rows, and each row of floating tabs may have any suitable number of openings and floating tabs 160 .

[0108] For example, the patterned frame structure 156c of the alternative embodiment of the tubular support structure 150c shown in Figures 30-31 has floating tabs 160 arranged in four circumferentially aligned sets (rows) 160a-160d and four associated openings 162 arranged in the circumferentially aligned sets (rows). In particular, the diameter of the tubular support structure 150c is smaller than the diameter of the tubular support structure 150a shown in Figures 23-27, such that the four rows of openings 162 are sufficient to impart a radially isotropic primary bending stiffness to the tubular support structure 150c, while the four rows of floating tabs are sufficient to impart a radially isotropic secondary bending stiffness to the tubular support structure 150c.

[0109] As another example, the alternative embodiment of tubular support structure 150d shown in Figure 32 is similar to tubular support structure 150c shown in Figures 30-31, except that each row of floating tabs has only two floating tabs 160 and each associated row of apertures has only two apertures 162. As a result, the width of each of the resulting lateral members 170 of tubular support structure 150d is greater than the width of each of the lateral members 170 of tubular support structure 150c shown in Figures 30-31, and therefore the primary bending stiffness of tubular support structure 150d is greater than the primary bending stiffness of tubular support structure 150c.

[0110] 23-27 , each floating tab 160 includes a cantilevered end in the form of a stem element 176 and a free end in the form of an expansion element 178. In the illustrated embodiment, each floating tab 160 is T-shaped, with the stem element 176 forming the base of the "T" and the expansion element 178 forming the cross of the "T." In the illustrated embodiment, the opposing ends of the expansion element 178 are generally straight, although in alternative embodiments, the opposing ends of the expansion element 178 may be rounded. The stem elements 176 reside within respective axial channels 168 and extend axially from each pair of circumferentially aligned transverse members 170, across respective transverse slots 164, and into respective retainer openings 166. In this manner, the stem elements 176 remain fixed to their respective transverse members 170 and therefore move with them.

[0111] 28A-28B, stem elements 176 are mechanically coupled between each pair of circumferentially aligned transverse members 170 via bridge members 180. Enlarged elements 178 are geometrically similar to, but smaller in size than, the retainer openings 166 such that the enlarged elements 178 are free to move axially within the retainer openings 166 to alternately engage and disengage abutment edges 182 of the respective retainer openings 166 (particularly, the extensions 172 of the pairs of transverse members 170 associated with the two most adjacent rows of openings relative to the row of openings associated with each transverse member 170).

[0112] Thus, each expansion element 178 of each floating tab 160 is configured to translate in one axial direction 184a within its respective retainer opening 166, thereby engaging the abutment edge 182 of the respective retainer opening 166, when the patterned frame structure 156a is laterally deflected in a bending direction toward the floating tab 160 or stretched axially (as best shown in FIG. 28B ). At this point, each floating tab 160 can be considered active or actuated. In particular, each bridge member 180 to which the stem element 176 of each floating tab 160 is attached flexes, causing the expansion element 178 of each floating tab 160 to translate in the axial direction 184a to engage the abutment edge 182 of the respective retainer opening 166.

[0113] Conversely, the expansion element 178 of each floating tab 160 is configured to axially translate in the opposite axial direction 184b within the respective retainer opening 166, thereby disengaging from the abutting edge 182 of the respective retainer opening 166, once the patterned frame structure 156a is straightened and / or axially relaxed (as best shown in FIG. 28A ). At this point, the respective floating tab 160 can be considered inactive or deactivated. In particular, the respective bridge member 180 to which the stem element 176 of the respective floating tab 160 is attached relaxes, causing the expansion element 178 of the respective floating tab 160 to axially translate in the axial direction 184b and disengage from the abutting edge 182 of the respective retainer opening 166.

[0114] Although the retainer openings 166 and associated floating tabs 160 are all axially oriented and configured to axially translate in the same axial direction 184a so that all of the expansion elements 178 engage the abutting edges 182 of the retainer openings 166 when the patterned frame structure 156a is laterally deflected or axially stretched, and are configured to axially translate in the same axial direction 184b so that all of the expansion elements 178 disengage from the abutting edges 182 of the retainer openings 166 when the patterned frame structure 156a is straightened and / or axially relaxed, some of the retainer openings 166 and associated floating tabs 160 may be axially oriented such that all of the expansion elements 178 disengage from the abutting edges 182 of the retainer openings 166 when the patterned frame structure 156a is straightened and / or axially relaxed. It will be appreciated that such first set of enlarged elements 178 may be axially opposite to the others of the floating tabs 160 such that when the patterned frame structure 156a is laterally deflected or axially stretched, the first set of enlarged elements 176 may translate axially in the axial direction 184a and the second set of enlarged elements 178 may translate axially in the axial direction 184b to engage the abutting edge 182 of the retainer opening 166, and when the patterned frame structure 156a is straightened and / or axially relaxed, the first set of enlarged elements 176 may translate axially in the axial direction 184b and the second set of enlarged elements 178 may translate axially in the axial direction 184a to disengage from the abutting edge 182 of the retainer opening 166.

[0115] It should be appreciated that, similar to the floating tabs 110 shown in Figures 7-10, actuation of the floating tabs 160 may correspond to inflection points 204, 254 in the bending stiffness and tensile stiffness of the tubular support structure 150a shown in Figures 20-21. Thus, when the tubular support structure 150a is initially laterally deflected within a primary lateral deflection range or axially stretched within a primary axial stretch range, all of the floating tabs 160 are unactuated and the bending stiffness or tensile stiffness of the tubular support structure 150a is not modulated and therefore has a primary bending stiffness 200 within that primary lateral deflection range (shown in Figure 20) or a primary tensile stiffness 250 within that primary axial stretch range (shown in Figure 21). However, when the tubular support structure 150a is subsequently laterally deflected within a secondary lateral deflection range or axially stretched within a secondary axial stretch range, one or more of the floating tabs 160 are actuated, and the bending or tensile stiffness of the tubular support structure 150a is modulated (i.e., increased) so that it has one or more secondary bending stiffnesses 202 (shown in FIG. 20) that are greater than the primary bending stiffness 200 within the secondary lateral deflection range, or one or more secondary tensile stiffnesses 252 (shown in FIG. 21) that are greater than the primary tensile stiffness 250 within the secondary lateral deflection range.

[0116] In particular, the lengths of the floating tabs 160, and more particularly the lengths of the stem elements 176 of the floating tabs 160, can be designed to select the locations and number of bending stiffness inflection points 204 and tensile stiffness inflection points 254 of the tubular support structure 150a. In particular, the length of each stem element 176 defines the clearance between the expansion element 178 of the respective floating tab 160 and the abutment edge 182 of the respective retainer opening 166, thereby defining the locations of the bending stiffness inflection points 204 and tensile stiffness inflection points 254 of the tubular support structure 150a. That is, as the length of a particular stem element 176 increases, the clearance between the enlarged element 178 of each floating tab 160 and the abutment edge 182 of each retainer opening 166 correspondingly increases, thereby increasing the degree of lateral deflection at which a particular inflection point 204 occurs (i.e., the inflection point 204 moves to the right on the x-axis shown in FIG. 20) or increasing the degree of axial elongation at which a particular inflection point 254 occurs (i.e., the inflection point 254 moves to the right on the x-axis shown in FIG. 21). Conversely, as the length of a particular stem element 176 decreases, the clearance between the expansion element 178 of each floating tab 160 and the abutment edge 182 of each retainer opening 166 decreases, thereby decreasing the degree of lateral deflection at which a particular inflection point 204 occurs (i.e., the inflection point 204 moves to the left on the x-axis shown in FIG. 20) or decreasing the degree of axial extension at which a particular inflection point 254 occurs (i.e., the inflection point 254 moves to the left on the x-axis shown in FIG. 21).

[0117] The number of inflection points 204 in the bending stiffness of the tubular support structure, and correspondingly the number of inflection points 254 in the tensile stiffness of the tubular support structure, can be selected by appropriately varying the length between the stem elements 176 of different sets of floating tabs 160.

[0118] For example, the stem elements 176 of all of the floating tabs 160 of the tubular support structures 150a-150d shown in Figures 23-32 are uniform in length, such that all of the floating tabs 160 simultaneously engage (and therefore actuate) the abutment edges 182 of their respective patterned frame structures 156a-156d (shown in Figures 28A-28B). As a result, the bending stiffness of each of the tubular support structures 150a-150d has a single inflection point 204a that defines the boundary between the primary bending stiffness 200 and the secondary bending stiffness 202, and a single inflection point 254a that defines the boundary between the primary tensile stiffness 250 and the secondary tensile stiffness 252.

[0119] In contrast, the stem elements 176 of the floating tabs 160 of the tubular support structure 150e shown in Figures 33-34 are unequal in length. In particular, in each floating tab row (only rows 160a-160d are shown), the stem elements 176 of a first set of floating tabs 160' are longer than the stem elements 176 of a different second set of floating tabs 160", such that the two sets of floating tabs 160 engage (and therefore actuate) the abutment edges 182 of the patterned frame structure 156e at two different times. As a result, the bending stiffness of tubular support structure 150e has two inflection points 204a, 204b, one inflection point 204a defining the boundary between primary bending stiffness 250 and secondary bending stiffness 202a, and a second inflection point 204b defining the boundary between the two secondary bending stiffnesses 202a, 202b, as shown in Figure 20. And, the tensile stiffness of tubular support structure 150e has two inflection points 254a, 254b, one inflection point 254a defining the boundary between primary tensile stiffness 250 and secondary tensile stiffness 252a, and a second inflection point 254b defining the boundary between the two secondary tensile stiffnesses 252a, 252b, as shown in Figure 21.

[0120] The first and second sets 160', 160'' of floating tabs are alternated and have an equal number of rows of floating tabs in each; however, in alternative embodiments, the first and second sets 160', 160'' of floating tabs may have a different number of floating tabs in each (e.g., one floating tab may be provided in the first set of floating tabs 160' and three floating tabs may be provided in the second set of floating tabs 160''), or a different order or arrangement of the first and second sets of floating tabs 160', 160'' may be provided (e.g., two immediately adjacent floating tabs 160' may be provided at one end of the row of floating tabs and two immediately adjacent floating tabs 160'' may be provided at the other end of the row of floating tabs).

[0121] It should be appreciated that the stem elements 176 of more than two floating tabs 160 may have different lengths such that two or more sets of floating tabs 160 engage (and thus actuate) the abutment edge 182 of the retainer opening 166 at two or more different times. As a result, the bending stiffness of the tubular support structure will have more than two inflection points 202, i.e., one inflection point 204a defining the boundary between the primary bending stiffness 200 and the secondary bending stiffness 202a, and two or more inflection points 204b, etc. defining the boundary between three or more secondary bending stiffnesses 202a, 202b, etc. And, the tensile stiffness of the tubular support structure will have more than two inflection points 252, i.e., one inflection point 254a defining the boundary between the primary tensile stiffness 250 and the secondary tensile stiffness 252a, and two or more inflection points 254b, etc. defining the boundary between at least three secondary tensile stiffnesses 202a, 202b, etc.

[0122] In particular, the length of a pair of extensions 172 can be designed to select the magnitude of secondary bending stiffness 202a, 202b or secondary bending stiffness 202a (shown in FIG. 20) or secondary tensile stiffness 252a, 252b or tensile stiffness 252a (shown in FIG. 21). In particular, the length of each pair of extensions 172 defines the flexibility of the abutting edge 182 of the respective retainer opening 166. That is, as the length of a particular pair of extensions 172 increases, the flexibility of the abutting edge 182 of the respective retainer opening 166 increases, thereby decreasing the magnitude of secondary bending stiffness 202a (profiles 202a, 202b) or secondary tensile stiffness 252a (or profiles 252a, 252b). In contrast, as the length of a particular pair of extensions 172 decreases, the flexibility of the abutting edge 182 of the respective retainer opening 166 decreases, thereby increasing the degree of secondary bending stiffness 202a (or profiles 202a, 202b) or secondary tensile stiffness 252a (or profiles 252a, 252b).

[0123] For example, the lengths of the pairs of extensions 172 of the tubular support structures 150a-150e shown in Figures 23-34 are relatively short. This results in a relatively low flexibility of the abutting edges 182 of each retainer opening 166 of the patterned frame structures 156a-156e, and therefore a relatively high degree of secondary bending stiffness 202a (profiles 202a, 202b) or secondary tensile stiffness 252a (or profiles 252a, 252b) of the tubular support structures 150a-150e. In contrast, the lengths of the pairs of extensions 172 of the tubular support structure 150f shown in Figures 35-36 are relatively long. This results in a relatively high degree of flexibility at the abutting edge 182 of each retainer opening 166 in the patterned frame structure 156f, and therefore a relatively low degree of secondary bending stiffness 202a (profiles 202a, 202b) or secondary tensile stiffness 252a (or profiles 252a, 252b) of the tubular support structure 150f. Note that the lateral dimensions of the retainer openings 166 in the patterned frame structure 156f of Figures 35-36 are greater than the lateral dimensions of the retainer openings 166 in the patterned frame structures 156a-156e of Figures 23-34, allowing for the accommodation of longer pairs of extensions 172.

[0124] In the illustrated embodiment, only a single row of floating tabs is responsible for modulating the bending stiffness of any of the tubular support structures 150a-150f when the tubular support structure is laterally deflected in the bending direction toward the respective floating tab row (e.g., for tubular support structure 150a shown in FIG. 26, floating tab row 160b at the outer edge of the curve is active, while the remaining seven floating tab rows 160a, 160c-160h are inactive). To this end, each retainer opening 166 and associated floating tab 160 of each patterned frame structure 156a-156f (as shown in Figures 28A-28B) is positioned so that there is sufficient clearance between the floating tab 160 and the edge 186 of each retainer opening 166 opposite the abutment edge 182, such that when patterned frame structure 156a is deflected laterally in a bending direction within the primary and secondary lateral deflection ranges more than 90° away from a single floating tab row at the outer edge of the curve, the floating tabs 160 of each of the other floating tab rows do not engage the edge 186 of their respective retainer opening 166 when axially translated in the axial direction 184b (as best shown in Figure 28A) and therefore do not contribute to the bending stiffness of tubular support structures 150a-150f.

[0125] In an alternative embodiment, as shown in FIGS. 37A-37C, pairs of diametrically opposed floating tabs together serve to modulate the bending stiffness of one of the tubular support structures 150a-150f when deflected laterally in a bending direction toward one of the diametrically opposed floating tab rows (e.g., for the patterned frame structure 156a shown in FIG. 26, floating tab row 160b at the outer edge of the curve and floating tab row 160f at the inner edge of the curve are active, while the remaining six floating tab rows 160a, 160c-160e, and 160g-160h are inactive).

[0126] In this case, as shown in Figures 37B-37C, each retainer opening 166 is preferably provided with two pairs of extensions 172 forming abutment edges 182, 186 at opposite ends of the retainer opening 166, with each expansion element 178 adapted to engage one of the abutment edges 182, 186 upon axial translation in either direction 184a, 184b. Thus, as shown in Figure 37B, the expansion element 178 of each floating tab 160 is configured to translate in one axial direction 184a within its respective retainer opening 166, thereby engaging the abutment edge 182 of its respective retainer opening 166, upon laterally deflection in a bending direction toward the floating tab 160 or axial stretching. At this point, each floating tab 160 can be considered active or actuated. In particular, each bridge member 180 to which the stem element 176 of each floating tab 160 is attached flexes, causing the enlarged element 178 of each floating tab 160 to translate axially 184a into engagement with the abutment edge 182 of the respective retainer opening 166.

[0127] Conversely, as shown in FIG. 37A , the expansion element 178 of each floating tab 160 is configured to axially translate in the opposite axial direction 184 b within the respective retainer opening 166, thereby disengaging from the abutting edge 182 of the respective retainer opening 166, once the tubular support structure is straightened and / or axially relaxed. At this point, the respective floating tab 160 can be considered inactive or deactivated. In particular, the respective bridge member 180 to which the stem element 176 of the respective floating tab 160 is attached is relaxed, causing the expansion element 178 of the respective floating tab 160 to axially translate in the axial direction 184 b and disengage from the abutting edge 182 of the respective retainer opening 166.

[0128] 37C , the expansion element 178 of each floating tab 160 is configured to further translate axially 184 b within the respective retainer opening 166, thereby engaging the abutment edge 186 of the respective retainer opening 166, as the tubular support structure is laterally deflected in a bending direction away from the floating tab 160. At this point, the respective floating tab 160 can be considered to be activated or actuated. In particular, the respective bridge members 180 to which the stem elements 176 of the respective floating tabs 160 are attached flex, causing the expansion element 178 of the respective floating tab 160 to translate axially 184 b into engagement with the abutment edge 186 of the respective retainer opening 166.

[0129] The retainer openings 166 can be designed so that when the patterned frame structure 156a is laterally deflected in a bending direction toward one of the two opposing floating tab rows, at least some of the floating tabs 160 of the diametrically opposed floating tab rows engage their respective retainer openings 166 simultaneously (to create a secondary bending stiffness) or at different times (to create two secondary bending stiffnesses, a first bending stiffness caused by a floating tab of one of the diametrically opposed floating tab rows first engaging a corresponding retainer opening 166, and a second bending stiffness caused by a floating tab of a second bending stiffness of the other diametrically opposed floating tab row).

[0130] Notwithstanding the above, it should be understood that when any of tubular support structures 150a-150f is laterally deflected in bending between adjacent pairs of floating tab rows (e.g., floating tab rows 160a and 160b of tubular support structure 150a shown in FIG. 26), each pair of floating tab rows may contribute to modulating the bending stiffness of tubular support structure 150a-150f. In this case, the floating tabs 160 of adjacent pairs of floating tab rows axially translate in the same direction to engage their respective retainer openings 166.

[0131] Having described the function and structure of various elongated intravascular medical devices, one method 350 of using an elongated intravascular medical device 300 (e.g., the guidewire 10 shown in Figures 1-3, the catheter 50 shown in Figures 4-6, or any other elongated intravascular medical device such as a guide sheath or an intravascular implant delivery wire) will now be described with reference to Figure 38 and Figures 39A-39H.

[0132] In this embodiment, the elongate intravascular medical device 300 has a lengthwise portion 304 that includes a tubular support structure 306 (e.g., the tubular support structure 100 shown in FIGS. 7-10 or the tubular support structure 100′ shown in FIG. 11 ) that is capable of transitioning from a primary bending stiffness to one or more radially isotropic secondary bending stiffnesses (in this embodiment, one of two secondary bending stiffnesses) (e.g., from the primary bending stiffness 200 to one of the low secondary bending stiffness 202a or high secondary bending stiffness 202b shown in FIG. 20 ), and correspondingly, from a primary tensile stiffness to one or more secondary tensile stiffnesses (in this embodiment, one of two secondary tensile stiffnesses) (e.g., from the primary tensile stiffness 250 to one of the low secondary tensile stiffness 252a or high secondary tensile stiffness 252b shown in FIG. 21 ). In the illustrated embodiment, the length 304 of the elongate intravascular medical device 300 comprises the distal end of the elongate intravascular medical device 300, although in the alternative, the length 304 of the elongate intravascular medical device 300 may be located proximal to the distal end of the elongate intravascular medical device 300. In the illustrated embodiment, mechanical property modulating elements 308 spaced axially along the tubular support structure 306 are actuated to transition the primary bending stiffness to a secondary bending stiffness.

[0133] In conventional fashion, an elongated intravascular medical device 300 is first introduced into a patient's vasculature 302, for example, via the patient's femoral artery near the groin (step 352) (see Figure 39A).

[0134] Next, the length 304 of the elongate intravascular medical device 300 is advanced distally through a first curve 310 of the patient's vasculature 302 (step 354) (see FIG. 39B). While the length 304 of the elongate intravascular medical device 300 is advanced distally within the first curve 310, the tubular support structure 306, and thus the length 304 of the elongate intravascular medical device 300, has a primary bending stiffness (e.g., primary bending stiffness 200 shown in FIG. 20). That is, the first curve 310 is relatively gentle, and thus the tubular support structure 306, and thus the length 304 of the elongate intravascular medical device 300, deflects laterally within a primary lateral deflection range and thus maintains its primary bending stiffness. In this manner, the length 304 of the elongate intravascular medical device 300 can pass through the first curve 310 with relatively little compliance force (due to the low lateral force).

[0135] The length 304 of the elongate intravascular medical device 300 is then advanced distally (step 356) through a second curve 312 having a curvature greater than the curvature of the first curve 310 (see FIG. 39C). For purposes of this specification, if the minimum radius of curvature of a particular curve is less than the minimum radius of curvature of the other curves, then the particular curve has a greater curvature than the other curves in the patient's vasculature; and if the minimum radius of curvature of a particular curve is greater than the minimum radius of curvature of the other curves, then the particular curve has a lesser curvature than the other curves in the patient's vasculature.

[0136] The primary bending stiffness of the tubular support structure 306, and therefore the primary bending stiffness of the length 304 of the elongate intravascular medical device 300, transitions to one of two secondary bending stiffnesses (e.g., the low secondary bending stiffness 200a or the high secondary bending stiffness 200b shown in FIG. 20 ) in response to distal advancement of the length 304 of the elongate intravascular medical device 300 within the second curve 312 (step 358). That is, the second curve 312 is relatively tight, causing the tubular support structure 306, and therefore the length 304 of the elongate intravascular medical device 300, to deflect laterally within the secondary lateral deflection range, thereby transitioning to the secondary bending stiffness. This makes the length 304 of the elongate intravascular medical device 300 less likely to dislodge when introduced through the second curve 312 (due to the increased support provided by the tubular support structure 306). In particular, if the second curve 312 is not too tight, then when the length 304 of the elongate intravascular medical device 300 is advanced distally within the second curve 312, the tubular support structure 306, and thus the length 304 of the elongate intravascular medical device 300, will deflect laterally in the lower region of the secondary lateral deflection range, thereby transitioning to a lower bending stiffness 202a. Alternatively, if the second curve 312 is sufficiently tight, then when the length 304 of the elongate intravascular medical device 300 is advanced distally within the second curve 312, the tubular support structure 306, and thus the length 304 of the elongate intravascular medical device 300, will deflect laterally in the upper region of the secondary lateral deflection range, thereby transitioning to a higher bending stiffness 202b.

[0137] Next, the length 304 of the elongate intravascular medical device 300 is advanced distally through a third curve 314 (step 360), which has a curvature that is less than the curvature of the second curve 312 (see FIG. 39D). The secondary bending stiffness of the tubular support structure 306, and therefore the secondary bending stiffness of the length 304 of the elongate intravascular medical device 300, transitions back to a primary bending stiffness (e.g., primary bending stiffness 202 shown in FIG. 20) in response to the distal advancement of the length 304 of the elongate intravascular medical device 300 through the third curve 314 (step 362). That is, the third curve 314 has a lower curvature, and therefore the tubular support structure 306, and therefore the length 304 of the elongate intravascular medical device 300, deflects laterally within the primary lateral deflection range, and therefore returns to its primary bending stiffness. In this manner, the length 304 of the elongate intravascular medical device 300 can pass through the third curve 314 with relatively little compliance force (due to the low lateral force).

[0138] Next, the length 304 of the elongate intravascular medical device 300 is advanced distally within a fourth curve 316 (step 364), which has a curvature that is greater than the curvature of the first curve 310 but different from the curvature of the second curve 312 (see FIG. 39E). The primary bending stiffness of the tubular support structure 306, and therefore the length 304 of the elongate intravascular medical device 300, transitions to the other of the two secondary bending stiffnesses in response to the distal advancement of the length 304 of the elongate intravascular medical device 300 within the fourth curve 316 (step 366). That is, the fourth curve 316 is relatively tight, causing the tubular support structure 306, and therefore the length 304 of the elongate intravascular medical device 300, to deflect laterally within the secondary lateral deflection range, thereby transitioning to the secondary bending stiffness. This makes the length 304 of the elongate intravascular medical device 300 less likely to slip out when introduced through the fourth curve 316 (due to the added support provided by the tubular support structure 306).

[0139] If the curvature of the fourth bend 316 is greater than the curvature of the second bend 312, the secondary bending stiffness to which the primary bending stiffness of the length 304 of the elongate intravascular medical device 300 transitions in response to distal advancement of the length 304 of the elongate intravascular medical device 300 within the fourth bend 316 may be the higher secondary stiffness 202b shown in Figure 20. On the other hand, the secondary bending stiffness to which the primary bending stiffness of the length 304 of the elongate intravascular medical device 300 transitions in response to distal advancement of the length 304 of the elongate intravascular medical device 300 within the second bend 312 may be the lower secondary stiffness 202a shown in Figure 20.

[0140] In contrast, if the curvature of the fourth bend 316 is less than the curvature of the second bend 312, the secondary bending stiffness to which the primary bending stiffness of the length 304 of the elongate intravascular medical device 300 transitions in response to distal advancement of the length 304 of the elongate intravascular medical device 300 within the fourth bend 316 may be a lower secondary stiffness 202a as shown in Figure 20. Meanwhile, the secondary bending stiffness to which the primary bending stiffness of the length 304 of the elongate intravascular medical device 300 transitions in response to distal advancement of the length 304 of the elongate intravascular medical device 300 within the second bend 312 may be a higher secondary stiffness 202b as shown in Figure 20.

[0141] Of course, in alternative embodiments, the respective curvatures of the second curved portion 312 and the fourth curved portion 316 may not be so different as to result in different secondary bending stiffnesses in response to distal advancement of the longitudinal portion 304 of the elongated intravascular medical device 300 within the respective second curved portion 312 or fourth curved portion 316 within the patient's vasculature 302.

[0142] The elongated intravascular medical device 300 is advanced distally within the patient's vasculature 302 (step 368) until the distal end of the elongated intravascular medical device 300 is located at the target site 318 (see FIG. 39F), where an additional medical procedure (therapeutic and / or diagnostic) is performed at the target site 318 (step 370). For example, if the elongated intravascular medical device 300 is a guidewire, an additional catheter can be advanced distally over the guidewire to the target site 318 and operated to perform a therapeutic and / or diagnostic procedure at the target site 318. If the elongated intravascular medical device 300 is a catheter, a therapeutic and / or diagnostic procedure can be performed by the catheter at the target site 318. If the elongated intravascular medical device 300 is a guide sheath, an additional catheter can be advanced distally through the guide sheath to the target site 194 and operated to perform a therapeutic and / or diagnostic procedure at the target site 194. When the elongated intravascular medical device 300 is a vascular implant delivery wire, the elongated intravascular medical device 300 can be operated in conjunction with a vascular implant delivery catheter to deploy the vascular implant at the target site 318 .

[0143] While the elongate intravascular medical device 300 is advanced distally within the patient's vasculature 302, the tubular support structure 306, and thus the lengthwise portion 304 of the elongate intravascular medical device 300, has a primary tensile stiffness (e.g., primary tensile stiffness 250 shown in FIG. 21 ). However, in certain situations (e.g., if the distal end of the elongate intravascular medical device 300 has been advanced distally within an undesired portion of the patient's vasculature 302 (see FIG. 39G ) or if it is desired to move the elongate intravascular medical device 300 proximally to unanchor its distal end (e.g., if it has become dislodged within the patient's vasculature 302, trapped due to vasospasm or interference with another intravascular medical device), it may be desirable to reorient its distal end, reposition it relative to the target site, or otherwise move the elongate intravascular medical device 300 proximally. The elongated intravascular medical device 300 is pulled (indicated by arrow 320) (see FIG. 39H), such as to deploy an intravascular implant from the device 300. The primary tensile stiffness of the tubular support structure 306, and therefore the length portion 304 of the elongated intravascular medical device 300, transitions to one of two secondary tensile stiffnesses (e.g., the lower secondary tensile stiffness 252a or the higher secondary tensile stiffness 252b shown in FIG. 20) in response to the pulling of the elongated intravascular medical device 300 (step 374). The device 300 is axially stretched within a secondary axial stretch range, thereby transitioning the length 304 of the elongated intravascular medical device 300 to a secondary tensile stiffness. This makes the length 304 of the elongated intravascular medical device 300 less susceptible to plastic deformation and damage. Once the distal end of the elongated intravascular medical device 300 is positioned within the vasculature at an appropriate location (e.g., proximal to a bifurcation 313) to remedy the problem (see FIG. 39I), the elongated intravascular medical device 300 is then relaxed (step 39J). The secondary tensile stiffness of the tubular support structure 306, and therefore the length 304 of the elongate intravascular medical device 300, transitions back to the primary tensile stiffness (e.g., primary tensile stiffness 250 shown in FIG. 20) in response to relaxation of the elongate intravascular medical device 300 (step 378). The length 304 of the elongate intravascular medical device 300 can then be advanced distally through, for example, a second curve 312 having a curvature greater than the curvature of the first curve 310 (see FIG. 39C).

[0144] It should be understood that steps 352-378 may be performed in any order and any number of times, depending largely on the nature of the order and number of bends encountered by the elongated intravascular medical device 300 from the initial introduction of the elongated intravascular medical device 300 into the patient's vasculature 302 until the distal end of the elongated intravascular medical device 300 is located at the target site 318.

[0145] Referring now to Figures 40 and 41A-41I, another method 400 of using an elongated intravascular medical device 300' (e.g., the guidewire 10 shown in Figures 1-3, the catheter 50 shown in Figures 4-6, or any other elongated intravascular medical device such as a guide sheath or an intravascular implant delivery wire) will be described.

[0146] In this embodiment, the elongated intravascular medical device 300' has a longitudinal portion 304' that includes a tubular support structure 306' (e.g., the tubular support structure 100' shown in Figures 12-13 or the tubular support structure 100''' shown in Figures 15-16) that is transitionable from a radially isotropic bending stiffness (e.g., the primary bending stiffness 200 shown in Figure 20) to a radially anisotropic bending stiffness (e.g., either of the secondary bending stiffnesses 202a, 202b shown in Figure 20) having at least one low circumferential region 208a and at least one high circumferential region 208b (e.g., as shown in Figures 15 and 18-19). In the illustrated embodiment, length portion 304' of elongate intravascular medical device 300' constitutes the distal end of elongate intravascular medical device 300', although in the alternative, length portion 304' of elongate intravascular medical device 300' may be located proximal to the distal end of elongate intravascular medical device 300'. In the illustrated embodiment, mechanical property modulating elements 308 spaced axially along tubular support structure 306' are actuated to modulate the bending stiffness of length portion 304' of elongate intravascular medical device 300'.

[0147] Method 400 differs primarily from method 350 described above with respect to FIG. 38 in that, prior to entering the curved portion of the patient's vasculature 302, the elongated intravascular medical device 300' is rotated about its longitudinal axis such that, as the lengthwise portion 304' of the elongated intravascular medical device 300' is advanced distally within the curved portion of the patient's vasculature 302, the radially isotropic bending stiffness of the lengthwise portion 304' of the elongated intravascular medical device 300' can be selectively transitioned to either a circumferential region 208a having a relatively low degree of radially anisotropic bending stiffness or a circumferential region 208b having a relatively high degree of radially anisotropic bending stiffness.

[0148] In the same manner as described above with respect to steps 352 and 354, the elongated intravascular medical device 300' is first introduced into the patient's vasculature 302, for example, via the patient's femoral artery near the groin (step 402) (see FIG. 41A), and the longitudinal portion 304' of the elongated intravascular medical device 300' is advanced distally within the first curved portion 310 (step 404) (see FIG. 41B) while having a radially isotropic bending stiffness. Because the curvature of the first curved portion 310 is not high enough to transition the radially isotropic bending stiffness of the lengthwise portion 304' of the elongated intravascular medical device 300' to a radially anisotropic bending stiffness, the elongated intravascular medical device 300' does not need to be rotated about its longitudinal axis before entering the first curved portion 310 to select whether to transition the radially isotropic bending stiffness of the lengthwise portion 304' of the elongated intravascular medical device 300' to a circumferential region 208a with a relatively low degree of radially anisotropic bending stiffness or a circumferential region 208b with a relatively high degree of radially anisotropic bending stiffness.

[0149] Next, length 304' of elongate intravascular medical device 300' is advanced distally through second curve 312 (step 406) (see FIG. 41C). The curvature of second curve 312 is high enough to transition the radially isotropic bending stiffness of length 304' of elongate intravascular medical device 300' to a radially anisotropic bending stiffness. In particular, due to the radially anisotropic nature of the secondary bending stiffness, when the physician orients or rotates the lengthwise portion 304' of the elongated intravascular medical device 300' into the curvature of the second curved portion 312, the circumferential region 208a (shown in Figures 15, 18, and 19) of the relatively low degree of radially anisotropic bending stiffness 202 of the tubular support structure 306', and therefore the lengthwise portion 304' of the elongated intravascular medical device 300' (i.e., the most flexible bending direction of the lengthwise portion 304' of the elongated intravascular medical device 300'), aligns with the curvature of the second curved portion 312, thereby allowing the distal tip of the elongated intravascular medical device 300' to continue advancing distally along the second curved portion 312 past the bifurcation 313 and not be misdirected past the bifurcation 313 into the straight portion 315 of the vasculature 302 (see Figure 41D) (step 408). In this manner, the distal tip of the elongated intravascular medical device 300'

[0150] If the longitudinal portion 304' of the elongated intravascular medical device 300' is unable to advance distally through the second curve 312 (e.g., if the longitudinal portion 304' of the elongated intravascular medical device 300' becomes dislodged within the second curve 312 (see FIG. 41E)) (step 410), the distal tip of the elongated intravascular medical device 300' can be repositioned just beyond the bifurcation in the vasculature 302 by slightly retracting the longitudinal portion 304' of the elongated intravascular medical device 300' (indicated by arrow 320) (step 412). Next, the elongate intravascular medical device 300' is rotated about its longitudinal axis (indicated by arrow 322) so that the circumferential region 208b (shown in FIG. 15, 18, or 19) of relatively high degree of radially anisotropic bending stiffness 202 of the tubular support structure 306', and therefore the length portion 304' of the elongate intravascular medical device 300' (i.e., the least flexible bending direction of the length portion 304' of the elongate intravascular medical device 300'), is aligned with the curvature of the second curved portion 312 (step 414). For example, in the illustrated case, the elongate intravascular medical device 300' can be rotated about its longitudinal axis until the curvature of the second curved portion 312 is aligned with one of the sets of mechanical property modulating elements 308 (see FIG. 41F). Alternatively, if the tubular support structure 306' includes all four of the rows of modulation elements 110a-110d, and at least two of the rows of modulation elements 110a-110d modulate the tubular support structure 306', the elongated intravascular medical device 300' can be rotated about its longitudinal axis until the curvature of the second curve 312 aligns with one of the sets of mechanical property modulation elements 308 corresponding to the circumferential region 208b of high radially anisotropic bending stiffness 202. As a result, the radially isotropic bending stiffness of the tubular support structure 306', and thus the length portion 304' of the elongated intravascular medical device 300', transitions to a circumferential region of relatively high radially anisotropic bending stiffness (e.g., either of the secondary bending stiffnesses 202a, 202b shown in FIG. 20 ), and thus is advanced distally within the second curve 312.

[0151] Next, length 304' of elongate intravascular medical device 300' is advanced distally through second curve 312 (step 416). Length 304' of elongate intravascular medical device 300' is then advanced distally within third curve 314 (step 418) (see FIG. 41H) in the manner described above with respect to step 360 of FIG. 38, and in response to distal advancement of length 304' of elongate intravascular medical device 300' within third curve 314, the radially anisotropic bending stiffness of tubular support structure 306', and therefore length 304' of elongate intravascular medical device 300', returns to a radially isotropic bending stiffness (e.g., primary bending stiffness 202 shown in FIG. 20) (step 420). Because the curvature of the third bend 314 is not sufficiently high to transition the radially isotropic bending stiffness of the lengthwise portion 304' of the elongated intravascular medical device 300' to a radially anisotropic bending stiffness, it is not necessary to rotate the elongated intravascular medical device 300' about its longitudinal axis before entering the third bend 314 to select whether the lengthwise portion 304' of the elongated intravascular medical device 300' should transition to a circumferential region with a relatively low degree of radially anisotropic bending stiffness or a circumferential region with a relatively high degree of radially anisotropic bending stiffness.

[0152] Length portion 304' of elongate intravascular medical device 300' is then advanced distally through fourth curve 316 in the same manner as elongate intravascular medical device 300' was advanced distally through second curve 312 as described above with respect to steps 406-414. In the same manner as described above with respect to steps 368 and 370, elongate intravascular medical device 300' is then advanced distally within the patient's vasculature 302 until the distal end of elongate intravascular medical device 300' is located at target site 318 (step 422) (see FIG. 41I), after which a further medical (therapeutic and / or diagnostic) procedure is performed at target site 318 (step 424).

[0153] It should be understood that steps 402-424 may be performed in any order and any number of times, depending largely on the nature of the order and number of bends encountered by the elongated intravascular medical device 300' from the initial introduction of the elongated intravascular medical device 300' into the patient's vasculature 302 until the distal end of the elongated intravascular medical device 300' is located at the target site 318.

[0154] While particular embodiments have been shown and described herein, those skilled in the art will understand that they are not intended to limit the disclosed invention, and it will be apparent to those skilled in the art that various changes, substitutions, and modifications (e.g., various dimensions of parts, combinations of parts) may be made without departing from the scope of the disclosed invention, which is defined solely by the appended claims and their equivalents. Accordingly, the specification and drawings are to be regarded in an illustrative and not a restrictive sense. The various embodiments shown and described herein are intended to cover alternatives, modifications, and equivalents of the disclosed invention, which are encompassed within the scope of the appended claims.

Claims

1. 1. A tubular support structure for use with an elongated intravascular medical device, comprising: an elongated tubular body; a patterned framework formed within the elongated tubular body; a lumen axially disposed within the elongate tubular body; a first set of floating tabs spaced axially along the patterned frame structure, each of the first set of floating tabs having a cantilevered end attached to the patterned frame structure and a free end configured to move relative to and thereafter engage the patterned frame structure when the tubular support structure is laterally deflected in a first bending direction.

2. 2. The tubular support structure of claim 1, wherein each of the first set of floating tabs is configured to move relative to the patterned frame structure when the tubular support structure is in a primary lateral deflection range and to engage the patterned frame structure when the tubular support structure is in a secondary lateral deflection range that is greater than the primary lateral deflection range.

3. 3. The tubular support structure of claim 2, wherein the tubular support structure has a primary bending stiffness when the tubular support structure is in the primary lateral deflection range and one or more secondary bending stiffnesses greater than the primary bending stiffness when the tubular support structure is in the secondary lateral deflection range.

4. The tubular support structure of claim 3 , wherein the one or more secondary bending stiffnesses include a plurality of different secondary bending stiffnesses.

5. The tubular support structure of claim 3 , wherein the highest value of the one or more secondary bending stiffnesses is less than five times the primary bending stiffness.

6. The tubular support structure of claim 3 , wherein the highest value of the one or more secondary bending stiffnesses is less than twice the primary bending stiffness.

7. 4. The tubular support structure of claim 3, wherein the primary bending stiffness is radially isotropic and each of the one or more secondary bending stiffnesses is radially anisotropic, each secondary bending stiffness having at least one circumferential region of relatively low stiffness and at least one circumferential region of relatively high stiffness.

8. The tubular support structure of claim 7 , wherein the magnitude of each of said at least one relatively low circumferential region is equal to the magnitude of said primary bending stiffness.

9. The tubular support structure of claim 7 , wherein the magnitude of each of the at least one relatively low circumferential region is greater than the magnitude of the primary bending stiffness.

10. The primary bending stiffness is 0.0689476 Pa (0.00001 in ２ 4. The tubular support structure of claim 3, wherein the tubular support structure has a tensile strength greater than 1 / 2 inch (-1 / 2 lb).

11. 11. A tubular support structure according to any preceding claim, wherein a free end of each of the first set of floating tabs is configured to translate relative to, and in turn engage, the patterned frame structure as the tubular support structure is axially stretched.

12. 12. The tubular support structure of claim 11, wherein each of the first set of floating tabs is configured to translate relative to the patterned frame structure when the tubular support structure is in a first range of axial extension and to engage with the patterned frame structure when the tubular support structure is in a second range of axial extension greater than the first range of axial extension.

13. 13. The tubular support structure of claim 12, wherein the tubular support structure has a first tensile stiffness when the tubular support structure is in the first range of axial extension and one or more second tensile stiffnesses greater than the first tensile stiffness when the tubular support structure is in the second range of axial extension.

14. The tubular support structure of claim 13 , wherein the one or more secondary tensile stiffnesses comprise a plurality of different tensile stiffnesses.

15. The tubular support structure of claim 1 , wherein said first set of floating tabs are circumferentially aligned on said patterned frame structure.

16. The tubular support structure of claim 1 , wherein said first set of floating tabs are circumferentially offset on said patterned frame structure.

17. 11. The tubular support structure of claim 1, wherein the first set of floating tabs are configured to incrementally engage the patterned frame structure as the tubular support structure deflects laterally in the first bending direction.

18. The tubular support structure of claim 17 , wherein at least two of the floating tabs have different lengths.

19. 2. The tubular support structure of claim 1, further comprising a second set of floating tabs axially spaced along the patterned frame structure and circumferentially offset from the first set of floating tabs, each of the second set of floating tabs having a cantilevered end fixed to the patterned frame structure and a free end configured to translate relative to and subsequently engage the patterned frame structure when the tubular support structure is deflected laterally in a second bending direction different from the first bending direction.

20. 20. The tubular support structure of claim 19, wherein the second set of floating tabs are circumferentially offset 180 degrees from the first set of floating tabs, and the second bending direction is opposite the first bending direction.

21. 20. The tubular support structure of claim 19, wherein the first set of floating tabs are configured to translate relative to the patterned frame structure in a first axial direction and the second set of floating tabs are configured to translate relative to the frame in a second axial direction opposite the first axial direction when the tubular support structure is deflected laterally in the first direction.

22. 22. The tubular support structure of claim 21, wherein the first set of floating tabs are configured to continue translating in the first axial direction relative to the patterned frame structure after all of the second set of floating tabs have engaged the patterned frame structure, and the second set of floating tabs are configured to continue translating in the second axial direction relative to the patterned frame structure after all of the first set of floating tabs have engaged the patterned frame structure.

23. The tubular support structure of claim 1 , wherein each of said first set of floating tabs extends axially along said patterned framework.

24. 2. The tubular support structure of claim 1, wherein the patterned frame structure has a plurality of substantially transverse slots disposed at least partially within the elongated tubular body, the substantially transverse slots being axially spaced apart along the tubular support structure to form a plurality of substantially transverse members and a plurality of connecting members rigidly connecting the substantially transverse members, and wherein a cantilevered end of each of the floating tabs is secured to a respective one of the substantially transverse members.

25. 25. The tubular support structure of claim 24, wherein the connecting members extend axially along the patterned framework.

26. 25. The tubular support structure of claim 24, wherein the substantially transverse slot is disposed completely through the elongate tubular body.

27. 2. The tubular support structure of claim 1, wherein each of the first set of floating tabs comprises a stem element and an enlarged element forming a cantilevered end and a free end, respectively, of each tab.

28. 28. The tubular support structure of claim 27, wherein each of the first set of floating tabs is T-shaped.

29. 28. The tubular support structure of claim 27, wherein the patterned frame structure comprises a plurality of retainer openings at least partially disposed within the elongated tubular body, and wherein an enlarged element of each of the first set of floating tabs is configured to translate within a respective one of the retainer openings and then engage an abutting edge of each of the retainer openings when the tubular support structure is deflected laterally in a first bending direction.

30. 30. The tubular support structure of claim 29, wherein each of the retainer openings is coaxial with a respective one of the substantially transverse slots, and wherein a stem element of each of the first set of floating tabs extends from the respective transverse member, across a respective one of the substantially transverse slots, and into the respective retainer opening.

31. 31. The tubular support structure of claim 30, wherein each adjacent pair of substantially transverse members includes a pair of extensions that form a channel between one of the retainer openings and one of the substantially transverse slots, a stem element of each of the first set of floating tabs nested within one of the channels, and each pair of extensions defines an abutting edge of a respective retainer opening.

32. 32. The tubular support structure of claim 31, wherein each pair of extensions is configured to flex laterally when the enlarged element of the respective floating tab engages the abutting edge of the respective retainer opening.

33. A tubular support structure according to any preceding claim, wherein the tubular body is a hypotube.

34. 1. An elongated intravascular medical device comprising: an elongated polymer tube; and a tubular support structure according to claim 1 coaxially disposed within said polymer tube.

35. 35. The elongate intravascular medical device of claim 34, wherein the tubular support structure is disposed at a distal end of the polymer tube.

36. 35. The elongate intravascular medical device of claim 34, wherein the tubular support structure is disposed proximal to the distal end of the polymer tube.

37. 1. An elongated intravascular medical device comprising: A core wire; and a tubular support structure according to claim 1 disposed on the distal end of said core wire.

38. 1. An elongated intravascular medical device comprising: A tubular support structure according to claim 1; an inner polymeric liner disposed within the lumen of the tubular body of the tubular support structure.

39. 1. A tubular support structure for use with an elongated intravascular medical device, comprising: an elongated tubular body; a patterned framework formed within the elongated tubular body; a lumen axially disposed within the elongate tubular body; a first set of mechanical property modulating elements spaced axially along the patterned framework, the first set of mechanical property modulating elements configured to gradually increase a finite bending stiffness of the tubular support structure in response to laterally deflecting the tubular support structure in a first bending direction.

40. 40. The tubular support structure of claim 39, wherein each of the first set of mechanical property modulating elements comprises a floating tab having a cantilevered end fixed to the patterned frame structure and a free end configured to translate relative to and then engage the patterned frame structure as the tubular support structure deflects laterally in the first bending direction, thereby increasing the finite bending stiffness of the tubular support structure.

41. 40. The tubular support structure of claim 39, wherein the first set of mechanical property modulating elements is further configured to increase a finite tensile stiffness of the tubular support structure in response to axially stretching the tubular support structure.

42. 40. The tubular support structure of claim 39, wherein the first set of mechanical property modulation elements are configured to incrementally increase the finite bending stiffness of the tubular support structure multiple times in response to laterally deflecting the tubular support structure in a first bending direction.

43. 40. The tubular support structure of claim 39, wherein the finite bending stiffness of the tubular support structure is increased by less than 500%.

44. 40. The tubular support structure of claim 39, wherein the finite bending stiffness of the tubular support structure is increased by less than 200%.

45. 40. The tubular support structure of claim 39, wherein the finite bending stiffness of the patterned tubular support structure is increased from an initial radially isotropic first order bending stiffness to a radially anisotropic second order bending stiffness, the second order bending stiffness having at least one relatively low degree circumferential region and at least one relatively high degree circumferential region.

46. 46. ​​A tubular support structure as claimed in claim 45, wherein the magnitude of each of said at least one relatively low circumferential region is equal to the magnitude of said primary bending stiffness.

47. 46. ​​A tubular support structure as claimed in claim 45, wherein the magnitude of each of said at least one relatively low circumferential region is greater than the magnitude of said primary bending stiffness.

48. The finite bending stiffness of the patterned tubular support structure is 0.0689476 Pa (0.00001 in ２ 40. The tubular support structure of claim 39, wherein the bending stiffness increases from an initial bending stiffness greater than -1 lb.

49. 40. The tubular support structure of claim 39, wherein the first set of mechanical property modulating elements are circumferentially aligned on the patterned framework.

50. 40. The tubular support structure of claim 39, wherein the first set of mechanical property modulating elements are circumferentially offset on the patterned frame structure.

51. 40. The tubular support structure of claim 39, further comprising a second set of mechanical property modulating elements axially spaced along the patterned frame structure and circumferentially offset from the first set of mechanical property modulating elements, the second set of mechanical property modulating elements configured to progressively increase a secondary bending stiffness of the tubular support structure in response to laterally deflecting the tubular support structure in a second bending direction different from the first bending direction.

52. 52. The tubular support structure of claim 51 , wherein the second set of mechanical property modulating elements are circumferentially offset 180 degrees from the first set of mechanical property modulating elements, and the second bending direction is opposite to the first bending direction.

53. 53. The tubular support structure of claim 52, wherein the second set of mechanical property modulating elements do not contribute to an increase in the primary bending stiffness of the tubular support structure when the tubular support structure is deflected laterally in the first bending direction, and the first set of mechanical property modulating elements do not contribute to an increase in the secondary bending stiffness of the tubular support structure when the tubular support structure is deflected laterally in the second bending direction.

54. 40. The tubular support structure of claim 39, wherein the patterned framework has a plurality of substantially transverse slots at least partially disposed within the elongated tubular body, the substantially transverse slots being axially spaced apart along the tubular support structure, thereby forming a plurality of substantially transverse members and a plurality of connecting members rigidly connecting the substantially transverse members to one another, and wherein each of the first set of mechanical property modulating elements is affixed to a respective one of the substantially transverse members.

55. 55. The tubular support structure of claim 54, wherein the connecting members extend axially along the patterned framework.

56. 55. The tubular support structure of claim 54, wherein the substantially transverse slot is disposed completely through the elongate tubular body.

57. 40. The tubular support structure of claim 39, wherein the tubular body is a hypotube.

58. 1. An elongated intravascular medical device comprising: an elongated polymer tube; and a tubular support structure according to claim 39 coaxially disposed within said polymer tube.

59. 59. The elongate intravascular medical device of claim 58, wherein the tubular support structure is disposed at a distal end of the polymer tube.

60. 59. The elongate intravascular medical device of claim 58, wherein the tubular support structure is disposed proximal to the distal end of the polymer tube.

61. 1. An elongated intravascular medical device comprising: A core wire; 40. An elongated intravascular medical device comprising: a tubular support structure according to claim 39 disposed on a distal end of said core wire.

62. 1. An elongated intravascular medical device comprising:

40. A tubular support structure according to claim 39; an inner polymeric liner disposed within the lumen of the tubular body of the tubular support structure.

63. 1. A tubular support structure for use with an elongated intravascular medical device, comprising: an elongated tubular body; a patterned framework formed within the elongated tubular body; a lumen axially disposed within the elongate tubular body; a first set of mechanical property modulating elements circumferentially spaced about the patterned frame structure, the first set of mechanical property modulating elements configured to gradually increase a finite tensile stiffness of the tubular support structure in response to axial stretching of the tubular support structure.

64. 64. The tubular support structure of claim 63, wherein each of the first set of mechanical property modulating elements comprises a floating tab having a cantilevered end fixed to the patterned frame structure and a free end configured to translate relative to the patterned frame structure as the tubular support structure is axially stretched and then engage the patterned frame structure, thereby increasing the finite tensile stiffness of the tubular support structure.

65. 64. The tubular support structure of claim 63, further comprising a second set of mechanical property modulating elements spaced circumferentially around the patterned framework and spaced axially from the first set of mechanical property modulating elements, the second set of mechanical property modulating elements configured to further increase the finite tensile stiffness of the tubular support structure in response to axial stretching of the tubular support structure.

66. 64. The tubular support structure of claim 63, wherein the first and second sets of mechanical property modulation elements are configured to progressively increase the finite tensile stiffness of the tubular support structure multiple times in response to axial stretching of the tubular support structure.

67. 64. The tubular support structure of claim 63, wherein the finite tensile stiffness of the tubular support structure is increased by 50% or more.

68. 64. The tubular support structure of claim 63, wherein the finite tensile stiffness of the tubular support structure is increased by 100% or more.

69. 64. The tubular support structure of claim 63, wherein the first set of mechanical property modulating elements are circumferentially aligned on the patterned framework.

70. 64. The tubular support structure of claim 63, wherein the finite tensile stiffness of the patterned tubular support structure is increased from an initial tensile stiffness of greater than 0.05 pounds.

71. 64. The tubular support structure of claim 63, wherein the patterned framework has a plurality of substantially transverse slots at least partially disposed within the elongated tubular body, the substantially transverse slots being axially spaced apart along the tubular support structure, thereby forming a plurality of substantially transverse members and a plurality of connecting members rigidly connecting the substantially transverse members to one another, and wherein each of the first set of mechanical property modulating elements is affixed to a respective one of the substantially transverse members.

72. 72. The tubular support structure of claim 71, wherein the connecting members extend axially along the patterned framework.

73. 72. The tubular support structure of claim 71, wherein the substantially transverse slot is disposed completely through the elongate tubular body.

74. 64. The tubular support structure of claim 63, wherein the tubular body is a hypotube.

75. 64. A tubular support structure as claimed in claim 63, wherein said tubular support structure has a finite bending stiffness that increases as said finite tensile stiffness increases.

76. 76. The tubular support structure of claim 75, wherein the first set of mechanical property modulating elements is configured to progressively increase the finite bending stiffness as the finite tensile stiffness progressively increases.

77. 1. An elongated intravascular medical device comprising: an elongated polymer tube; and a tubular support structure according to claim 63 coaxially disposed within said polymer tube.

78. 64. The elongate intravascular medical device of claim 63, wherein the tubular support structure is disposed at a distal end of the polymer tube.

79. 64. The elongate intravascular medical device of claim 63, wherein the tubular support structure is disposed proximal to the distal end of the polymer tube.

80. 1. An elongated intravascular medical device comprising: A core wire; 64. An elongated intravascular medical device comprising: a tubular support structure according to claim 63 disposed on a distal end of said core wire.

81. 1. An elongated intravascular medical device comprising:

64. A tubular support structure according to claim 63; an inner polymeric liner disposed within the lumen of the tubular body of the tubular support structure.

82. 1. A tubular support structure for use with an elongated intravascular medical device, comprising: a tubular support structure; an elongated tubular body comprising an elongated tubular body having a patterned framework and an internal lumen; and a plurality of mechanical property modulating elements disposed on the patterned framework structure, the plurality of mechanical property modulating elements being configured to modulate the radially isotropic bending stiffness of the tubular support structure in response to laterally deflecting the patterned framework structure in one or more bending directions, such that the tubular support structure has a radially anisotropic bending stiffness.

83. 83. The tubular support structure of claim 82, wherein each of the plurality of mechanical property modulating elements comprises a floating tab having a cantilevered end fixed to the patterned frame structure and a free end configured to translate relative to and then engage the patterned frame structure as the tubular support structure deflects laterally in the first bending direction, thereby modulating the radially isotropic bending stiffness of the tubular support structure.

84. 83. The tubular support structure of claim 82, wherein the plurality of mechanical property modulating elements comprises one or more sets of mechanical property modulating elements spaced axially along the frame structure, the one or more sets of mechanical property modulating elements configured to modulate a radially isotropic bending stiffness of the tubular support structure in response to respective lateral deflections of the tubular support structure in one or more bending directions.

85. 83. The tubular support structure of claim 82, wherein the one or more sets of mechanical property modulating elements comprise multiple sets of mechanical property modulating elements circumferentially offset from one another around the patterned frame structure, and the one or more sets of bending directions include multiple different bending directions.

86. 86. The tubular support structure of claim 85, wherein two sets of mechanical property modulating elements are circumferentially offset 180 degrees from each other.

87. 87. A tubular support structure as described in claim 86, wherein each of said one or more radially anisotropic second-order bending stiffnesses has at least one circumferential region of relatively low stiffness and at least one circumferential region of relatively high stiffness.

88. 88. A tubular support structure as set forth in claim 87, wherein a magnitude of each of said at least one relatively low degree circumferential region is equal to a magnitude of said primary bending stiffness.

89. 88. A tubular support structure as set forth in claim 87, wherein a magnitude of each of said at least one relatively low degree circumferential region is greater than a magnitude of said primary bending stiffness.

90. 88. The tubular support structure of claim 87, wherein each of the at least one relatively low degree circumferential region is centered on a circumferential position of the patterned frame structure where the set of the plurality of mechanical property modulating elements is not present, and each of the at least one relatively high degree circumferential region is centered on a circumferential position of the patterned frame structure where the set of the plurality of mechanical property modulating elements is present.

91. 88. The tubular support structure of claim 87, wherein each of the at least one relatively low magnitude circumferential region is centered about a circumferential position of the patterned framework structure where a first set of multiple mechanical property modulating elements is present, and each of the at least one relatively high magnitude circumferential region is centered about a circumferential position of the patterned framework structure where a second set of multiple mechanical property modulating elements is present, the first and second sets of mechanical property elements modulating the patterned framework structure in different manners.

92. 83. The tubular support structure of claim 82, wherein the patterned framework has a plurality of substantially transverse slots at least partially disposed within the elongated tubular body, the substantially transverse slots being axially spaced apart along the tubular support structure, thereby forming a plurality of substantially transverse members and a plurality of connecting members rigidly connecting the substantially transverse members to one another, and wherein each of the plurality of mechanical property modulating elements is affixed to a respective one of the substantially transverse members.

93. 92. The tubular support structure of claim 91, wherein the connecting members extend axially along the elongate tubular body.

94. 94. The tubular support structure of claim 93, wherein the substantially transverse slot is disposed completely through the elongate tubular body.

95. 83. The tubular support structure of claim 82, wherein the tubular body is a hypotube.

96. 1. An elongated intravascular medical device comprising: an elongated polymer tube; and a tubular support structure according to claim 82 coaxially disposed within said polymer tube.

97. 96. The elongate intravascular medical device of claim 95, wherein the tubular support structure is disposed at the distal end of the polymer tube.

98. 96. The elongate intravascular medical device of claim 95, wherein the tubular support structure is disposed proximal to the distal end of the polymer tube.

99. 83. The elongate intravascular medical device of claim 82, further comprising an inner polymeric liner disposed within the lumen of the tubular body of said tubular support structure.

100. 1. An elongated intravascular medical device comprising: an elongated polymer tube; and a tubular support structure according to claim 82 coaxially disposed within said polymer tube.

101. 101. The elongate intravascular medical device of claim 100, wherein the tubular support structure is disposed at the distal end of the polymer tube.

102. 101. The elongate intravascular medical device of claim 100, wherein the tubular support structure is disposed proximal to the distal end of the polymer tube.

103. 1. An elongated intravascular medical device comprising: A core wire; 83. An elongated intravascular medical device comprising: a tubular support structure according to claim 82 disposed on a distal end of said core wire.

104. 1. An elongated intravascular medical device comprising: a tubular support structure according to claim 82; an inner polymeric liner disposed within the lumen of the tubular body of the tubular support structure.

105. 1. A method of distally advancing an elongated intravascular medical device within a patient's vasculature, comprising: introducing the elongated intravascular medical device into the vascular system of a patient; advancing a longitudinal portion of the elongated intravascular medical device distally into a first curve in the patient's vasculature while the longitudinal portion has a primary bending stiffness; advancing the longitudinal portion of the elongated intravascular medical device distally into a second curve within the patient's vasculature, the second curve having a curvature greater than the curvature of the first curve; transitioning a primary bending stiffness of the length of the elongate intravascular medical device to a secondary bending stiffness greater than the primary bending stiffness in response to distal advancement of the length of the elongate intravascular medical device within the second curve; and advancing the elongated intravascular medical device distally within the patient's vasculature until a distal end of the elongated intravascular medical device is located at a target site within the patient's vasculature.

106. 106. The method of claim 105, wherein the longitudinal portion is a distal end of the elongated intravascular medical device.

107. 106. The method of claim 105, wherein the longitudinal portion is proximal to a distal end of the elongate intravascular medical device.

108. 106. The method of claim 105, wherein the elongated intravascular medical device is one of a guidewire, a catheter, a guide sheath, and an intravascular implant delivery wire.

109. 106. The method of claim 105, wherein a length of the elongated intravascular medical device has a patterned framework that imparts a primary bending stiffness to the elongated intravascular medical device.

110. 110. The method of claim 109, wherein the elongated intravascular medical device has mechanical property modulating elements spaced axially along the patterned framework, the mechanical property modulating elements configured to transition the primary bending stiffness to the secondary bending stiffness in response to distal advancement of a lengthwise portion of the elongated intravascular medical device within the second curve.

111. further comprising the step of distally advancing a longitudinal portion of the elongated intravascular medical device into a third curve within the patient's vasculature, the third curve having a curvature less than the curvature of the second curve; and transitioning a secondary bending stiffness of the lengthwise portion of the elongated intravascular medical device to the primary bending stiffness in response to distal advancement of the lengthwise portion of the elongated intravascular medical device within the third curve.

112. further, advancing the longitudinal portion of the elongate intravascular medical device distally into a fourth curve within the patient's vasculature, the fourth curve having a curvature greater than the curvature of the first curve and different from the curvature of the second curve; and transitioning a primary bending stiffness of the length portion of the elongate intravascular medical device to another bending stiffness different from the secondary bending stiffness in response to distal advancement of the length portion of the elongate intravascular medical device within the fourth curve.

113. further comprising the step of pulling the elongated intravascular medical device; and transitioning a primary tensile stiffness of a lengthwise portion of the elongate intravascular medical device to a secondary tensile stiffness greater than the primary tensile stiffness in response to tensioning the elongate intravascular medical device.

114. 106. The method of claim 105, wherein the secondary bending stiffness of the length of the elongate intravascular medical device is radially anisotropic, the radially anisotropic bending stiffness having circumferential regions of relatively low and relatively high bending stiffness, the method further comprising the step of rotating the elongate intravascular medical device about its longitudinal axis such that the radially isotropic bending stiffness of the length of the elongate intravascular medical device transitions to the circumferential region of relatively high bending stiffness as the rotated length of the elongate intravascular medical device is advanced distally within the second curve.

115. 115. The method of claim 114, wherein the magnitude of the circumferential region of relatively low secondary bending stiffness is equal to the magnitude of the primary bending stiffness.

116. 115. The method of claim 114, wherein the magnitude of the circumferential region of relatively low secondary bending stiffness is greater than the magnitude of the primary bending stiffness.

117. 115. The method of claim 114, further comprising, prior to the step of rotating the elongated intravascular medical device about its longitudinal axis, advancing a length portion of the elongated intravascular medical device distally into a second curve while having a circumferential region with a relatively low degree of secondary bending stiffness such that the length portion of the elongated intravascular medical device cannot be successfully advanced distally through the second curve, and retracting the length portion of the elongated intravascular medical device proximally.

118. 106. The method of claim 105, wherein the maximum secondary bending stiffness is less than 500% of the primary bending stiffness.

119. 106. The method of claim 105, wherein the maximum secondary bending stiffness is less than 200% of the primary bending stiffness.

120. 106. The method of claim 105, further comprising performing an additional medical procedure at a target site using the elongated intravascular medical device.

121. 1. A method of distally advancing an elongated intravascular medical device within a patient's vasculature, comprising: introducing the elongated intravascular medical device into the vascular system of a patient; advancing a length of the elongated intravascular medical device distally into a first curve in the patient's vasculature while the length has a radially isotropic bending stiffness; advancing the longitudinal portion of the elongated intravascular medical device distally into a second curve within the patient's vasculature, the second curve having a curvature greater than the curvature of the first curve; transitioning the radially isotropic bending stiffness of the elongate intravascular medical device length to a radially anisotropic bending stiffness in response to distal advancement of the elongate intravascular medical device length within the second curve; and advancing the elongated intravascular medical device distally within the patient's vasculature until a distal end of the elongated intravascular medical device is located at a target site within the patient's vasculature.

122. 122. The method of claim 121, wherein the longitudinal portion is a distal end of the elongated intravascular medical device.

123. 122. The method of claim 121, wherein the longitudinal portion is proximal to the distal end of the elongated intravascular medical device.

124. 122. The method of claim 121, wherein the elongated intravascular medical device is one of a guidewire, a catheter, a guide sheath, and an intravascular implant delivery wire.

125. 122. The method of claim 121, wherein a length of the elongated intravascular medical device has a patterned framework that provides the elongated intravascular medical device with a radially isotropic bending stiffness.

126. 126. The method of claim 125, wherein the elongated intravascular medical device has mechanical property modulating elements spaced axially along the patterned framework, the mechanical property modulating elements configured to transition from the radially isotropic bending stiffness to the radially anisotropic bending stiffness in response to distal advancement of a lengthwise portion of the elongated intravascular medical device within the second curve.

127. further comprising the step of distally advancing a longitudinal portion of the elongated intravascular medical device into a third curve within the patient's vasculature, the third curve having a curvature less than the curvature of the second curve; and transitioning a radially anisotropic bending stiffness of the lengthwise portion of the elongated intravascular medical device to a radially isotropic bending stiffness in response to distal advancement of the lengthwise portion of the elongated intravascular medical device within the third curve.

128. 128. The method of claim 127, wherein the radially anisotropic bending stiffness has a circumferential region of relatively low bending stiffness and a circumferential region of relatively high bending stiffness, the method further comprising the step of rotating the elongate intravascular medical device about its longitudinal axis such that the radially isotropic bending stiffness of the length portion of the elongate intravascular medical device transitions to the circumferential region of relatively high bending stiffness of radially anisotropic bending stiffness when the length portion of the rotated intravascular medical device is advanced distally within the second curve.

129. 129. The method of claim 128, wherein the magnitude of the circumferential region of relatively low secondary bending stiffness is equal to the magnitude of the primary bending stiffness.

130. 129. The method of claim 128, wherein the magnitude of the circumferential region of relatively low secondary bending stiffness is greater than the magnitude of the primary bending stiffness.

131. 129. The method of claim 128, further comprising, prior to the step of rotating the elongated intravascular medical device about its longitudinal axis, advancing a length portion of the elongated intravascular medical device distally into a second curve while having a circumferential region with a relatively low degree of secondary bending stiffness such that the length portion of the elongated intravascular medical device cannot be successfully advanced distally through the second curve, and retracting the length portion of the elongated intravascular medical device proximally.

132. 122. The method of claim 121, further comprising performing an additional medical procedure at a target site using the elongated intravascular medical device.

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