Patent Description:
Currently, there are a large number of different vascular catheters and microcatheters, each designed to enable access to different anatomical locations in the vasculature. A key issue that catheter design faces is controlling pushability and flexibility across the length of the catheter. Controlling pushability and flexibility is important in order to enable the physician to negotiate access through various complex and often tortuous, anatomical vasculature which is often found in the cardiovascular or neurovascular systems. One approach to modulating flexibility is to form the catheter body from different types of materials, e.g., stainless steel and or polymers, each of which has different functional properties. These materials may be combined into a tubular construction via a coiled or braid wire pattern set within a layered polymer composition. Another approach is to vary the cylindrical diameter and wall thickness of the catheter. Alternatively, a variety of different spiral-cuts can be introduced into the wall of the catheter, thereby increasing flexibility; these spiral cuts can either be continuous or discontinuous in nature. However, there are no current catheters which combine both different types of materials as well as different cut patterns in easy-to-assemble modules. Assembling a catheter from multiple modules, each of which is made from a different material, can be difficult because the physical properties of these materials make functional combination problematic, i.e., a stainless steel tube cannot be fused directly to a nitinol tube. However, assembling a catheter from different modules, each of which had different properties, would allow one to tailor the catheter to meet the particular requirements of different types of vascular anatomy. A known catheter is disclosed in <CIT>.

The present invention provides a way for assembling catheter modules each having different physical properties. The catheter properties can be tailored directly to meet a particular anatomical need. Thus, it is possible to specifically control flexibility, resistance to plastic deformation, axial torque transmission, and column strength of the catheter in an anatomically specific manner. The modular catheters of the present invention are particularly useful for supporting a guidewire and/or delivering an agent through a vessel stenosis or tortuous anatomy as is often encountered in the cardiovascular or neurovascular systems.

Embodiments of the present invention provide a catheter that comprises at least one proximal tubular module and a distal tubular module, each of the tubular modules having at least one section with spiral cuts, each pair of adjacent tubular modules are coupled by a joint, the joint comprising: (a) at least one snap-fit connector on a first tubular module and a snap-fit acceptor positioned on the adjacent tubular module, the snap-fit connector being elastically deformable when engaged, and at least one stabilizing element, including a tongue element positioned on the first tubular module or the adjacent tubular module, and a groove element positioned on the opposite, first tubular module or the opposite, adjacent tubular module, or (b) an interlocking shape having a plurality of protruding sections and receiving sections that mate with the protruding sections, each of the adjacent tubular modules in the pair having one or more of the plurality of protruding sections and the plurality of receiving sections,wherein the distal end of the distal tubular module has a crown comprising a plurality of curvilinear elements, especially curvilinear elements that are sinusoidal in shape, preferably <NUM>-<NUM> of said curvilinear elements.

In some implementations, the spiral-cuts comprise a plurality of interrupted spiral cuts.

The snap-fit connector may form a cantilever joint. In further implementations, the snap-fit connectors comprise a stem structure and a locking structure, wherein the width of the locking structure at the widest point as measured between opposite sides of the locking structure is greater than the width of the stem structure, and the snap-fit acceptor comprise a stem void and a locking void and wherein the width of the locking void at the widest point measured between opposite sides of the locking void is greater than width of the stem void. In certain embodiments, the locking structure can be formed in an oval shape and the snap-fit acceptor comprises a locking void formed in a circular shape. The snap-fit connector can bend at the cantilever joint at an angle ranging from about <NUM> to about <NUM>° with respect to a line parallel to a longitudinal axis running parallel with one of the at least one proximal tubular modules or the distal tubular module.

In some embodiments, the snap-fit connector forms a barb structure which when inserted into the snap-fit acceptor, then, after insertion deploys laterally and remains parallel during and after insertion with respect to a line parallel to the longitudinal axis of one of the at least one proximal tubular modules or the distal tubular module. In some implementations, the barb structure comprises an arrow shaped structure formed from two shafts.

In some embodiments, the distal tubular module is formed from Nitinol. Alternatively, the distal module can be formed from stainless steel of SAE grade selected from <NUM>, <NUM>, <NUM>, and <NUM>, <NUM>-<NUM> precipitation hardened stainless steel (PH), or Nickel Cobalt Alloy (MP35N).

To protect the joint between adjacent tubular modules, at least a portion of the joint can be enclosed with a tubular cover.

The catheter can comprise at least two cut openings, a first and a second cut opening that are positioned on the at least one proximal tubular modules or the distal tubular module. In some implementations, both cut openings are positioned on the distal tubular module. In other implementations, one cut opening is positioned on the distal tubular module and the second cut opening is positioned on one of the at least one proximal tubular modules. In some implementations, a filament is threaded in a spiral configuration around the outside of a tubular module. One end of the filament is positioned in the first cut opening and the other end of the filament is positioned in the second cut opening.

The filament can be fixed in position at the first and second openings. The filament can also be threaded in either clockwise or counterclockwise configuration around the one or more tubular modules on which is included. The filament can be fixed on one or more of the proximal tubular modules or the distal tubular module by at least one ring. In addition, the cross-sectional area of the filament can be circular, square, triangular, rectangular, half-circle or trapezoidal in shape.

In some embodiments, the catheter comprises between <NUM> and <NUM> tubular modules.

In some implementations, a polymer forming a jacket may be used to cover at least a portion of one or more of the at least one proximal tubular modules or the distal tubular module. In some implementations, the polymer jacket may be formed from nylon, polyether block amide, PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy alkane), PET (polyethylene terephthalate) or PEEK (polyether ether ketone).

In some embodiment of the catheter according to the present invention, the at least one proximal tubular module and the distal tubular module include an inner lumen and wherein at least a portion of the inner lumen of the proximal or distal tubular modules is coated with an inner lining. In some implementations, the inner lining may be formed from nylon, polyether block amide, PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy alkane), PET (polyethylene terephthalate) or PEEK (polyether ether ketone).

There are a number of ways in way the snap-fit connector and snap-fit acceptor can be secured to ensure a robust connection between adjacent tubular modules. For instance, the snap-fit connector and snap-fit acceptor can be glued together, welded together, and soldered to each other.

The at least one proximal tubular module and the distal tubular module can be formed from the same material or alternatively, from different materials. In certain embodiments, one or more of the at least one proximal tubular module is formed from stainless steel and the distal tubular module is formed from Nitinol. In some embodiments. one or more of the at least one tubular module and the distal tubular module is formed from a polymer. In some implementations, one or more of the at least one proximal tubular module and the distal tubular module is formed from a braided composite of metal and polymer.

In some embodiments, the outer diameter of a proximal tubular module adjacent to the distal tubular is the same as the outer diameter of the distal tubular module. In alternative embodiments, the outer diameter of the adjacent proximal tubular module is greater than the outer diameter of the distal tubular module.

In some implementations, the inner diameter of the distal tubular module is smaller than the inner diameter of the adjacent proximal tubular module. Alternatively, the inner diameter of the adjacent proximal tubular module can be equal to the inner diameter of the distal tubular module.

One or more of the at least one proximal tubular modules can have the same flexibility as the distal tubular module. Alternatively, the distal tubular module can have a greater flexibility than the flexibility of one or more of the at least one proximal tubular modules.

In embodiments of the catheter of the present invention, the catheter further comprises a tip that is attached to the crown of the distal tubular module. In some embodiments, the tip is tapered and further comprises radiopaque material impregnated within the tip material. The tip may be from a metal, such as, but not limited to, gold. The tip can be implemented as a hollow tubular body that is conically tapered. A filament may be spirally wound around a distal portion of the distal tubular module and the tip, and both the filament and tip can be covered with a jacket.

In some embodiments, the catheter is coated a hydrophilic lubricating polymer.

Embodiments of the catheter of the present invention also provide a catheter that comprises at least one proximal tubular module and a distal tubular module, each of the tubular modules having at least one section with spiral cuts, each pair of adjacent tubular modules being coupled by a joint, the joint comprising an interlocking shape having a plurality of protruding sections and receiving sections that mate with the protruding sections, each of the adjacent tubular modules in the pair having one or more of the plurality of protruding sections and the plurality of receiving sections.

In some implementations, the interlocking shape of the joint comprises a pattern of zig-zags. Alternatively, the interlocking shape of the joint comprises a wave form. The catheter joint may be covered with a jacket.

In some embodiments of the catheter of the present invention, the distal tubular module comprises at least one least one section having a spiral-cut, distal tubular module is formed from a shape-memory metal, wherein a segment or section of the distal tubular module is set in a curvilinear shape along a central luminal axis of the tubular module such that a constant cross-sectional lumen is maintained around the central luminal axis when the curvilinear shape is assumed by the distal tubular module. In some embodiments, At least a portion of the distal tubular module may be formed from Nitinol. In other embodiments, the distal tubular module is formed from a stainless steel material selected from the group of consisting of a stainless steel of SAE grade selected from <NUM>, <NUM>, <NUM>, and <NUM>, <NUM>-<NUM> precipitation hardened stainless steel (PH), Nickel Cobalt Alloy (MP35N) and mixtures thereof. Alternatively, the distal tubular module can be formed from a polymer. In some implementations, the section of the distal tubular module set in a curvilinear shape along maintains an angle ranging from about <NUM>° to about <NUM>° with respect with a segment of the distal tubular module not set in a curvilinear shape. In other embodiments the section of the distal tubular module set in a curvilinear shape along maintains an angle ranging from about <NUM>° to about <NUM>° with respect with a segment of the distal tubular module not set in a curvilinear shape. The curvilinear section be straightened using a guidewire. In some embodiments, the guidewire employed is tapered. In some implementations, section of the distal tubular module preset in a curvilinear shape converts to an angle of about <NUM>° with respect with a segment of the distal tubular module not set in a curvilinear shape when the guidewire is withdrawn from the tubular module. In other implementations, the section of the distal tubular module preset in a curvilinear shape converts to an angle of about <NUM>° with respect with a segment of the distal tubular module not set in a curvilinear shape when the guidewire is withdrawn from the tubular module.

Referring to <FIG>, a catheter <NUM> is formed from at least two tubular modules <NUM>, <NUM>, generally referred to as a proximal <NUM> and distal <NUM> tubular modules. Each tubular module has at least one section which can have at least one spiral-cut section. The spiral-cut section may extend along the full length of the tubular module or may be positioned only along one or more portions of the tubular module. The spiral-cut may be continuous or form an interrupted spiral pattern. In certain embodiments, there may be more than two tubular modules, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. or up to n, tubular modules linked together. If there are multiple tubular modules, e.g., > <NUM> tubular modules, the additional tubular modules serve or act as extensions of the proximal, tubular module. The tubular modules may be formed from hypotubes, which in certain embodiments may contain patterned cuts positioned on one end of the tubular module. The tubular modules may be formed from the same or different materials and may have the same or different outer or inner diameters. For example, the tubular modules can be made from similar metals (metals having similar physical properties, e.g., ultimate tensile strength (UTS), % elongation, or modulus of elasticity), two different metals, polymers, or formed from a combination of polymers and metals.

In one embodiment, the tubular modules may be joined together by a plurality of snap-fit connectors and snap-fit acceptors which are positioned on one end of either the same or different adjacent tubular modules.

The structure of the snap-fit connectors may vary. For example, in one embodiment, the snap-fit connector comprises a stem structure and a locking structure. The width of the locking structure at the widest point, as measured between opposite sides of the locking structure, is greater than width of the stem structure at its widest point, as measured between opposite sides of the stem. The shape of locking structure can vary. In one embodiment, the locking structure is an oval, while in a second embodiment, the shape is circular or semicircular. Other shapes for the locking structure are encompassed by the invention, including, square, rectangular, trapezoidal, diamond or triangular.

The snap-fit acceptor comprises a stem void and a locking void and, is positioned opposite the snap-fit connector on the opposing or adjacent tubular module. The structure of the snap-fit acceptor is the cut-out image corresponding to the geometric structure of the snap-fit connector.

<FIG> show an overview of the structure of the catheter <NUM>. In the embodiment shown, there are two tubular modules, a proximal tubular module <NUM> and a distal tubular module <NUM>. As used herein, the terms "proximal" and "distal" refer to the proximity of the tubular module to the hub <NUM> or the proximity to the cardiovascular system. In other words, the proximal tubular module is positioned closer to the hub <NUM> and more distant, as measured along the length of the catheter, from the heart, while the distal module is positioned closer to the heart and, thus, the coronary arteries. However, these terms only denote relative position and are not limiting with respect to the structure, length, shape or number of the tubular modules.

The proximal and distal tubular modules can be made from similar metals, different metals, polymers, or a combination of polymers and metals. Examples of materials that may be used include stainless steel (SST), nickel titanium (Nitinol), or polymers. Examples of other metals which may be used include, super elastic nickel titanium, shape memory nickel titanium, Ti-Ni, nickel titanium, approximately, <NUM>-<NUM> wt. % Ni, Ni-Ti-Hf, Ni-Ti-Pd, Ni-Mn-Ga, Stainless Steel (SST) of SAE grade in the <NUM> to <NUM> series e.g., <NUM>, <NUM>, <NUM>, <NUM>, MP35N, and <NUM>-<NUM> precipitation hardened (PH) stainless steel, other spring steel or other high tensile strength material or other biocompatible metal material. In one preferred embodiment, the material is superelastic of shape memory, nickel titanium, while in another preferred embodiment, the material is stainless steel.

The proximal and distal modules of present invention can include, in entirety, or in only in selected sections, a superelastic alloy generally referred to as "a shape-memory alloy. " Elements made of such shape memory alloys have the ability to resume their original shape after being deformed to such a degree that if they were made from an ordinary metal, they would undergo permanent deformation. Superelastic alloys useful in the invention include: Elgiloy® and Phynox® spring alloys (Elgiloy® alloy is available from Carpenter Technology Corporation of Reading Pa. ; Phynox® alloy is available from Metal Imphy of Imphy, France), SAE grade <NUM> stainless steel and MP35N (Nickel Cobalt) alloys which are available from Carpenter Technology corporation and Latrobe Steel Company of Latrobe, Pa. , and superelastic Nitinol which is available from Shape Memory Applications of Santa Clara, Calif. Further information regarding one or more of these alloys is disclosed in <CIT>.

The term "superelastic" refers to alloys having superelastic properties that include at least two phases: a martensitic phase, which has a relatively low tensile strength and which is stable at relatively low temperatures; and an austenitic phase, which has a relatively high tensile strength and which is stable at temperatures higher than the martensitic phase. Superelastic characteristics generally allow the metal to be deformed by collapsing and deforming the metal and creating stress which causes the Nitinol to change to the martensitic phase. More precisely, when stress is applied to a specimen of a metal such as Nitinol exhibiting superelastic characteristics at a temperature at or above that which the transformation of the martensitic phase to the austenitic phase is complete, the specimen deforms elastically until it reaches a particular stress level where the alloy then undergoes a stress-induced phase transformation from the austenitic phase to the martensitic phase. As the phase transformation progresses, the alloy undergoes significant increases in strain with little or no corresponding increases in stress. The strain increases while the stress remains essentially constant until the transformation of the austenitic phase to the martensitic phase is complete. Thereafter, further increase in stress is necessary to cause further deformation. The martensitic metal first yields elastically upon the application of additional stress and then plastically with permanent residual deformation. If the load on the specimen is removed before any permanent deformation has occurred, the martensitic specimen elastically recovers and transforms back to the austenitic phase. The reduction in stress first causes a decrease in strain. As stress reduction reaches the level at which the martensitic phase transforms back into the austenitic phase, the stress level in the specimen remains essentially constant (but less than the constant stress level at which the austenitic crystalline structure transforms to the martensitic crystalline structure until the transformation back to the austenitic phase is complete); i.e., there is significant recovery in strain with only negligible corresponding stress reduction. After the transformation back to austenite is complete, further stress reduction results in elastic strain reduction. This ability to incur significant strain at relatively constant stress upon the application of a load and to recover from the deformation upon the removal of the load is commonly referred to as superelasticity.

As discussed above, suitable superelastic alloys include nickel titanium (Nitinol) consisting essentially of <NUM> to <NUM> atom percent of Ni, Cu--Zn alloy consisting essentially of <NUM> to <NUM> wt % of Zn, Cu--Zn--X alloy containing <NUM> to <NUM> wt % of X (X=Be, Si, Sn, Al, or Ga), and Ni--Al alloy consisting essentially of <NUM> to <NUM> atom percent of Al. Nitinol is especially preferable. The mechanical properties of Nitinol can be changed as desired by replacing part of Ti--Ni alloy with <NUM> to <NUM> atom percent of another element X (X=Cu, Pd, or Zr) or selecting the reduction ratio of cold working and/or the conditions of the final heat treatment The buckling strength yielding stress when a load is increased) of the super elastic alloy used is <NUM> to <NUM>/mm<NUM> (<NUM>° C), preferably <NUM> to <NUM>/mm<NUM>, and the recovery stress (yielding stress when a load is decreased) is <NUM> to <NUM>/mm<NUM> (<NUM>° C), preferably <NUM> to <NUM>/mm<NUM>. Alternatively, the tubular modules may be formed from polymers. Examples of polymers include polyimide, PEEK, nylon, polyurethane, polyethylene terephthalate (PET), latex, HDHMWPE (high density, high molecular weight polyethylene) and thermoplastic elastomers.

The tubular modules may be made, for example, by forming a pipe of a super elastic metal and then removing the parts of the pipe where the notches or holes are to be formed. The notches, holes or cuts can be formed in the pipe by laser (YAG laser, for example), electrical discharge, chemical etching, mechanical cutting, or a combined use of any of these techniques. See <CIT>et al.

After deformation by heating and deformation into a preset shape, e.g., a curvilinear shape, the tubular module can be cooled. The tubular module is then restrained in the deformed condition within a delivery system to facilitate the insertion into an artery. Once the physical restraint on the tubular module is removed, the superelastic tubular module can return to its original undeformed shape, i.e., curvilinear.

In one embodiment, the proximal tubular module <NUM> may be made of <NUM> SST and the distal tubular module <NUM> is made of <NUM>-<NUM> SST. In another embodiment, the proximal tubular module <NUM> is made of <NUM>-<NUM> SST, while the distal tubular module <NUM> is made of Nitinol. Either the proximal tubular module <NUM> or the distal tubular module <NUM> may be made from a braided composition of materials as well. In other embodiments, either the proximal tubular module <NUM> or the distal tubular module <NUM> may be made from a cable or a braided wire.

Each tubular module <NUM>, <NUM> may have several different types of spiral-cut patterns, including both continuous as well as discontinuous spiral-cut patterns. The different spiral-cut patterns may be distributed on the same or different tubular modules.

The spiral-cut sections provide for a graduated transition in bending flexibility, as measured by pushability, kink resistance, axial torque transmission for rotational response, and/or torque to failure. For example, the spiral-cut pattern may have a pitch that changes to increase flexibility in one or more areas of the tubular module. The pitch of the spiral-cuts can be measured by the distance between points at the same radial position in two adjacent threads. In one embodiment, the pitch may increase as the spiral-cut progresses from a proximal position to the distal end of the catheter. In another embodiment, the pitch may decrease as the spiral-cut progresses from a proximal position on the catheter to the distal end of the catheter. In this case, the distal end of the catheter may be more flexible. By adjusting the pitch and the cut as well as the uncut path of the spiral-cuts, the pushability, kink resistance, torque, flexibility and compression resistance of the catheter, i.e., the tubular modules, may be adjusted. Thus, tubular modules having different rigidity or flexibility can be combined. For example, a comparatively rigid tubular module could be combined with relatively flexible tubular module. This combination could be further combined with a comparatively rigid of comparatively flexible tubular module.

By combining tubular modules with varying rigidity (conversely, flexibility), the catheter can traverse within a wide variety of different vasculature, especially, when the vascular anatomy is torturous or the lumen of the vasculature is compromised or obstructed, partially or completely, such as a Chronic Total Occlusion (CTO). The modular structure also provides for the ability to effectively transmit torque across the length of the catheter without kinking or narrowing or collapse of the lumen of the tubular modules. This combination of tubular modules with varying rigidity or flexibility allows the flexibility of the catheter to be adjusted across its length. In addition, the varying rigidity enables the flexibility of modular sections to go from more rigid to more flexible and then back to rigid again. This modulation of flexibility/rigidity across the length of the catheter allows it to be advanced into and function in various anatomical lumens and across lumen obstructions.

The modulation of flexibility/rigidity across the length of the catheter can be accomplished in a number of ways. For example, by varying the spiral-cut pattern variables (pitch, interruptions) and transitioning between spiral-cut patterns the flexibility/rigidity of a tubular module may be controlled. In addition, the spiral-cut pattern allows the cross-sectional diameter of the lumen to be maintained when the tubular module is bent or curved. Spiral-cut sections having different cut patterns may be distributed along the length of the tubular module. The spiral-cut patterns may be continuous or discontinuous along the length of the module. For example, there may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>,. n spiral-cut sections along the length of the module. The spiral-cut sections may be continuous or interrupted. Within each section a constant cut pattern may be present, but across different sections within a tubular module, the cut patterns may vary, e.g., in terms of pitch. Each section may also contain a variable pitch pattern within the particular section. Each spiral-cut section may have a constant pitch, e.g., in the range of from about <NUM> to about <NUM>, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. The pitch may also vary within each section. The pitches for different spiral-cut sections may be same or different. Alternatively, the catheter may be formed from tubular modules have a continuously changing spiral-cut pattern along the length of the catheter. The orientation or handedness of spiral-cut sections in the modules may also vary within the spiral-cut sections.

The width of the spiral cuts can vary, e.g., from about <NUM> micron to about <NUM> microns.

For an interrupted spiral-cut section, the interrupted spiral pattern can be designed such that each turn or rotation of the spiral includes a specific number of cuts, Nc (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc.). Nc can also be whole numbers, such as <NUM>, <NUM>, <NUM>, <NUM>,. n, as well as other real numbers, such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. At a given Nc, the uncut extent a and the cut extent β can be chosen as α= (<NUM>-(β*Nc))/Nc such that each rotation has Nc number of repeat patterns each comprising a cut portion of extent β adjacent an uncut portion of extent α. For example, at Nc = <NUM>, <NUM>, and <NUM>, the following table shows example choices of various embodiments for α and β:.

<FIG> shows one embodiment of the catheter in which two tubular modules, a proximal tubular module <NUM> and distal tubular module <NUM>, are joined together. In the embodiment, shown, a tip, <NUM>, is attached to a crown <NUM> at a distal end of the distal tubular module <NUM>. The two tubular modules are connected together at a joint <NUM>. The joint <NUM> is formed by snap-fit connector <NUM> and snap-fit acceptor <NUM> as illustrated in <FIG>, where the snap-fit connector <NUM> is locked-in or snapped into the snap-fit acceptor <NUM>; tubular modules are hollow and have an inner lumen as well as an outer wall. A hub <NUM> can be positioned at one end of the catheter <NUM>, and an intermediate tubular section <NUM> connects the hub <NUM> and proximal tubular module <NUM>. Any type of hub can be used with the catheter.

<FIG> show embodiments of spiral-cut sections of a tubular module that may be used on different portions of the proximal and distal tubular modules shown in <FIG>. The distal tubular module, <NUM> comprises an interrupted spiral-cut sections <NUM> (shown enlarged in <FIG>), <NUM> (shown enlarged in <FIG>), and <NUM> (shown enlarged in <FIG>) The proximal tubular module <NUM> comprises interrupted spiral-cut sections <NUM> (shown enlarged in <FIG>), <NUM> (shown enlarged in <FIG>), <NUM> (shown enlarged in <FIG>) and <NUM> (shown enlarged in <FIG>). The joint <NUM> between the proximal and distal tubular modules is shown in <FIG>. Note, in the embodiment shown, the snap-fit connector and span-fit acceptor are flush with the outer surface of the tubular modules, i.e., the outer portions of the snap-fit connector and acceptor do not protrude beyond the outer diameter of the tubular modules.

In the embodiments shown in <FIG>, the interrupted spiral-cuts are represented as being discontinuous. A detailed view of one embodiment of these spiral-cuts is shown in <FIG>, which depicts a portion of an unrolled (or flattened) tubular module having an interrupted spiral-cut pattern. The spiral-cut tube section of the tubular module shows a single, spiral ribbon portion having adjacent turns <NUM>, <NUM> which are substantially defined and separated by an interrupted spiral cut path width <NUM>. The spiral cut path width <NUM> includes alternating open or cut portions <NUM> and uncut portions <NUM>. The spiral pathway width <NUM> is composed of alternating cut and uncut sections <NUM> and <NUM> is angled with respect to a circumference of the tubular portion (in other words, the pitch angle φ shown in <FIG> of less than <NUM>°).

As illustrated in <FIG>, each helically-oriented uncut portion <NUM> has an arcuate extent "α" and each helically-oriented cut portion has an arcuate extent "β. " Angles α and β can be expressed in degrees (where each complete helical turn is <NUM>°). The uncut portions can be distributed such that adjacent uncut portions <NUM> are not in axial alignment (or "staggered") with each other along a direction parallel to the longitudinal axis L. As shown in <FIG>, the uncut portions <NUM> on every other turn of the interrupted spiral cut width <NUM> can be axially aligned.

The spiral-cut patterns of each tubular module can be formed from continuous spiral-cut sections, interrupted spiral-cut sections, or a hybrid of both types of spiral-cut patterns, where the various patterns are arranged in any order. The interrupted cut spiral modules have the ability to maintain a concentric lumen area while in a bent configuration, even in sharp bends of small radii. The ability to maintain a concentric lumen enables smooth wire movement, in either direction within the tubular lumen, without resulting in a deformation of the lumen. Additionally, using superelastic materials such as Nitinol for the spiral cut segments, allows segment to bend in tight curves through various vascular passageways without permanent lumen deformation.

The length of each of the tubular modules can vary. For example, the length of the proximal tubular module <NUM> can range from about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM> or about <NUM> to <NUM>. The length of the distal tubular module <NUM> can range from about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM> or about <NUM>-<NUM>.

In certain embodiments, the distal tubular module may be formed into a microcatheter. The microcatheter is capable of navigating over a guidewire into remote vasculature. The microcatheter may be capable of crossing a lesion and delivering the guidewire and/or contrast media across the lesion followed by, e.g., deployment of an interventional treatment element across the lesion, immediately restoring blood flow. The interventional treatment element may be a stent, a coil, a flow diverter, a flow restoration element, a thrombectomy element, a retrieval element, an aspirator or a snare.

<FIG> and <FIG> illustrate two different, preferred embodiments of snap-fit connectors and snap-fit acceptors that can be used to couple tubular modules according to the present invention. The embodiments are shown in a two-dimensional representation where the tubular module is flattened in a plane. In <FIG>, the proximal tubular module <NUM> which in this embodiment is formed from SST, is connected at the joint <NUM> to the adjacent distal tubular module, which is formed, in this embodiment, from Nitinol, by a snap-fit connector <NUM> and snap-fit acceptor <NUM>. In addition to the snap-fit connector <NUM> and snap-fit acceptor <NUM>, two stabilizing elements, <NUM>, <NUM> may be positioned on either lateral side of the snap-fit connector/snap-fit acceptor <NUM>, <NUM>. In the embodiment shown, the stabilizing elements are rectangular in shape, however, the shape of the stabilizing elements are not limited to a rectangular shape (e.g., trapezoidal, square or triangular).

There may be a plurality of snap-fit connectors and snap-fit acceptors connecting two adjacent tubular modules ranging from <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The snap-fit connector and/or the snap-fit acceptor can be positioned on either the proximal and/or the distal tubular modules. For example, the snap-fit connector can be on the distal tubular module and the snap-fit acceptor can be on the proximal tubular module or, alternatively, the snap-fit connector can be on the proximal tubular module and the snap-fit acceptor can be on the distal tubular module. The snap-fit connector and snap-fit acceptor form a pair on adjacent tubular modules.

The stabilizing elements can prevent the tubular modules from rotating independently, maintain concentric alignment and allow for transmission of torque across the proximal and distal modules along the length of the catheter. The management of torsion and shear stress in the modular catheter is thereby improved. The ratio between the shear stress and strain of a material is an elastic constant of the module (G). When an applied torque is balanced by the internal stress of the material, the torque on the cross-section resulting from sheer stress is: <MAT> where Θ is the angle of rotation, L is the length of the section and J is known as the "polar second moment of area".

With respect to hollow shafts, such as catheters, the expression for J is: <MAT> where D and d are the outside and inside diameters of the catheter (i.e., tubular modules). These equations yield an indication of the amount of torque that can be safely transferred along a catheter to prevent undue torsion.

The stabilizing elements can be implemented as tongue elements <NUM>, <NUM> that fit into corresponding grooves <NUM>, <NUM> on the opposite tubular module. Also in this embodiment, the snap-fit connector <NUM> forms a cantilevered joint formed on the distal tubular module <NUM>. In the embodiment shown, the snap-fit connector <NUM> includes a circular locking section <NUM> connected to the body of the proximal tubular module by a stem section <NUM>. The proximal tubular module <NUM> includes a corresponding snap-fit acceptor <NUM>, a space or receptacle, including a circular portion <NUM> to receive circular section <NUM> and a rectangular <NUM> portion to receive the stem section <NUM>. <FIG> shows the two tubular modules <NUM>, <NUM>, and joint <NUM> in <FIG> in an exploded view. The tubular modules are joined together by inserting the snap-fit connector <NUM> into the snap-fit acceptor <NUM>.

<FIG> illustrate another embodiment of a snap-fit joint. In this embodiment, the snap-fit connector, <NUM>, has two arms, <NUM>, <NUM>, each having a respective triangular or trapezoidal shaped head (also referred to as arrow or barb shaped), <NUM>, <NUM>, positioned at one end. The arms <NUM>, <NUM> have a springiness property and have leeway to pivot laterally with respect to the longitudinal axis, <NUM>, of the tubular module. In <FIG>, the snap-fit connector <NUM> is shown in the open position in which arms <NUM>, <NUM>, are displaced laterally relative to the longitudinal axis <NUM> of the tubular module. When inserted into the snap-fit acceptor, <NUM>, the arms <NUM>, <NUM> pivot inwardly and the angle between the arms and longitudinal axis of the tubular module decreases. After insertion, triangular shaped heads <NUM>, <NUM> move or flex outwardly again as shown in <FIG> fixing the snap-fit connector <NUM> in the snap-fit acceptor <NUM>. In other embodiments, other designs for snap-fit joints can be used including torsion and annular snap joints.

<FIG> illustrate various perspective views of the embodiment shown in <FIG>, where the proximal tubular module <NUM> and the distal tubular module <NUM> are linked together using the snap-fit connector <NUM> and snap-fit acceptor <NUM>, together with stabilizing tongue and groove elements <NUM>, <NUM>. In the embodiment shown in <FIG>, the stabilizing elements <NUM> and the snap-fit connector <NUM> are positioned at one end of a single tubular module <NUM>. In other embodiments, the snap-fit connector <NUM> and the stabilizing elements <NUM>, are positioned and employed on multiple tubular modules. Alternatively, each tubular module can contain a variety of different snap-fit connectors. For example, the snap connector, <NUM>, shown in <FIG>, could be combined with snap connector <NUM>, shown in <FIG>. Additionally, the embodiment shown in <FIG> shows a tubular cover <NUM> for the entire joint <NUM> or only a portion thereof, which can be made of a polymer or other material, e.g., metal.

As noted above, the snap-fit connector <NUM>, which can be positioned on either the distal or proximal tubular modules <NUM>, <NUM> may be formed from a stem structure <NUM> (<FIG>) which can be attached at a cantilever joint <NUM> to one end of either the proximal or distal tubular module. The attachment forms a cantilever joint <NUM>, which is elastically deformable, around which the stem structure <NUM> and locking structure <NUM> can bend at an angle Θ ranging from of about <NUM>° to about <NUM>° with respect to a line parallel to the longitudinal axis <NUM> of the first or second tubular module, as further illustrated in <FIG>. <FIG> show flattened views (where the tubular module has been cut, unrolled and laid flat) of the snap-fit connector <NUM> of cantilever joint <NUM> in a raised position. <FIG> is a side or sagittal view of the raised cantilever joint. <FIG> shows the joint from the perspective of the external surface of the tubular module. <FIG> shows the join from a top external view, while <FIG> shows the joint from the perspective of the internal surface of the tubular module. <FIG> show perspective views of the cantilever joint <NUM> with the snap-fit connector <NUM> in a raised position.

In addition to the snap-fit connectors, <NUM>, at least one stabilizing element comprises a tongue element e.g., <NUM> in one of the tubular modules and a groove element e.g., <NUM> in the connecting module. The stabilizing element <NUM> may be positioned laterally to the snap connector around the circumference of an end of the proximal or distal tubular module, <NUM>, <NUM> (a second stabilizing including tongue element <NUM> and groove element <NUM> are also shown in some of the figures (e.g., <FIG>). The stabilizing elements may assume a variety of different shapes, including, but not limited to, rectangular, trapezoidal, square, circular or triangular. Functionally, the role of the stabilizing elements <NUM> is illustrated in <FIG>. When the snap-fit connectors and acceptor <NUM>, <NUM> are joined together, the stabilizing elements shapes function to prevent the proximal and distal tubular modules <NUM>, <NUM> from rotating circumferentially at the joint <NUM> where the tubular modules have been connected. There may be one stabilizing elements (<FIG>), or alternatively there may be two or more stabilizing elements (<FIG>), e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. up to n stabilizing elements. The stabilizing elements allow for the transmission of force (torque) along the longitudinal length of the catheter.

The shape of the snap-fit connectors which are used to secure the two tubular modules together may vary. For example, in one embodiment, the snap-fit connector <NUM> of the proximal tubular module <NUM> has an acceptor in the form of an oval <NUM> with a stem structure <NUM>, while the snap-fit connector <NUM> has complementary shape in the form of an oval <NUM> and stem structure <NUM> which fits directly into the snap-fit acceptor <NUM>. This joining is illustrated in <FIG> where the tubular modules <NUM>, <NUM> are connected together, and in <NUM>(a)-<NUM>(b) where the two tubular modules are shown in an exploded view or separated from each other. <FIG> illustrate the snap-fit joint from several different views. In <FIG>, stabilizing elements <NUM> and the snap connector <NUM> are positioned laterally with respect to each other around the distal tubular member.

Other shapes for the snap-fit connectors are encompassed herein, including semicircular, oblong, triangular, trapezoidal or irregular, either individually or in combination with other shapes. In these designs, the maximum width of the locking structure <NUM>, measured between opposite sides, is greater than the width of the stem structure <NUM>. This configuration secures the snap-fit connector <NUM> within the snap-fit acceptor, preventing them from pulling apart from each other without first releasing the snap-fit connector.

The edges of the snap-fit connector <NUM> of the distal tubular module <NUM> and the edges of the snap-fit acceptor <NUM> of the proximal tubular module <NUM> may be beveled to ensure that the snap-fit connector and snap-fit acceptor are securely connected and will not separate or dislodge after insertion into the patient as illustrated in <FIG>. The angle θ of the bevel may range from about <NUM>° to about <NUM>° with respect to a line formed along the longitudinal axis of the proximal and distal tubular modules. The angle θ can range from about <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, or <NUM>° to about <NUM>°. The snap-fit connector and snap-fit acceptor can also be joined by gluing, soldering, laser welding, welding or enclosing within a ring or securing a jacket (tubular) over the joint. These modifications prevent the snap-fit from lifting out-of-plane.

As illustrated in <FIG>, which depict photomicrographs of the joint between snap-fit connectors and snap-fit acceptors according to embodiments of the present invention, the joint between the snap-fit connector <NUM> and snap-fit acceptor <NUM> may be flush, i.e., the surface of the snap-fit connector does not protrude above the outer surface (outer diameter) of the snap-fit acceptor and is level with the outer surface of the tubular modules.

<FIG> illustrate other embodiments of the types of joints between the proximal tubular module <NUM> and the distal tubular module <NUM>. In these embodiments, the proximal and distal tubular modules <NUM>, <NUM> have interlocking shapes including protruding sections <NUM>, <NUM> and receiving sections <NUM>, <NUM> at the joint <NUM> which interlock with each other. In the embodiment shown in <FIG>, the protruding section <NUM>, <NUM> and receiving sections <NUM>, <NUM> take the form of a wave, sinusoid, meandering or curvilinear elements. In another embodiment, <FIG>, interlocking shape <NUM> comprises protruding sections <NUM>, <NUM> and receiving sections <NUM>, <NUM> in the form of a triangular or zig-zag pattern. The interlocking shapes of the protruding and receiving sections used can all be the same, or there may be more than one type of protruding and receiving section on either the proximal and/or distal tubular modules.

In general, embodiments can include one or more, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. n, protruding sections and receiving sections. For example, in the embodiments illustrated in <FIG>, there are three protruding sections and corresponding receiving sections. Functionally, the protruding sections e.g., <NUM>, <NUM> and receiving sections e.g., <NUM>, <NUM>, prevent the proximal and distal tubular modules, <NUM>, <NUM> from rotating circumferentially at the joints where the tubular modules have been connected. The interlocking shape joints can be covered with a tubular jacket to help secure the joint.

As illustrated in cross-sectional views in <FIG>, the proximal and distal tubular modules <NUM>, <NUM> may have the same or different inner or outer diameters. The outer diameter of the proximal tubular module <NUM> or the distal tubular module <NUM> can range from about <NUM> to about <NUM>. The inner diameter of the proximal tubular module <NUM> or the distal tubular module <NUM> can range from about <NUM> to about <NUM>.

As shown in <FIG>, the inner diameter <NUM> of proximal tubular module <NUM> and the inner diameter <NUM> of distal tubular module <NUM> may be the same or approximately the same. In addition, the outer diameter <NUM> of the proximal tubular module <NUM> and the outer diameter <NUM> of the distal tubular module <NUM> may be the same or approximately the same.

Alternatively, as shown in <FIG>, the proximal tubular module <NUM> and the distal tubular module <NUM> may have the same inner diameter <NUM>, <NUM>, but have different respective outer diameters <NUM>, <NUM> (<FIG>). In this particular embodiment, the proximal tubular module <NUM> has a larger outer diameter <NUM> than the outer diameter <NUM> of the distal tubular module <NUM>. This is further illustrated in the embodiments shown in <FIG>. In this embodiment, at the joint between the proximal tubular member <NUM> and the distal tubular member <NUM>, the proximal tubular member <NUM> and the distal tubular member <NUM> form a <NUM>° angle with respect to each other due to the differences in their outer diameters <NUM>, <NUM>. <FIG> illustrates the difference in outer diameter <NUM> of the proximal tubular module <NUM> as compared to outer diameter <NUM> of the distal tubular module <NUM>. <FIG> shows a cross-sectional view of <FIG>. In the embodiment shown here, the inner diameter of both the proximal tubule <NUM> and distal tubular module <NUM> are the same.

In yet another embodiment, the proximal tubular module <NUM> can have both a larger inner diameter <NUM> and outer diameter <NUM> than the inner and outer diameters <NUM>, <NUM>, respectively, of the distal tubular module <NUM> (<FIG>). This distinction is further illustrated in <FIG>, which show partial and extended cross-sectional views of the embodiment shown in <FIG>. In this embodiment, at the joint <NUM> between the proximal tubular member <NUM> and the distal tubular member <NUM>, the inner diameter <NUM> and the outer diameter <NUM> of the distal tubular module <NUM> at the joint <NUM> are initially the same as the inner diameter <NUM> and outer diameter <NUM> of the proximal tubular module <NUM>. At the joint, the inner diameter <NUM> and outer diameter <NUM> of the distal tubular module <NUM> decreases in size until the inner diameter <NUM> and the outer diameter <NUM> of the distal tubular module <NUM> are smaller than the inner diameter <NUM> and outer diameter <NUM> of the proximal tubular module <NUM>. The decreases in size of the inner diameter <NUM> and outer diameter <NUM> may be linear or non-linear.

The proximal tubular module <NUM> or the distal tubular module <NUM> can have a varying diameter across its length, e.g., a tapered configuration. The tapering can be in any direction or may only be present along a portion of the tubular module.

The wall thickness of the proximal tubular module <NUM> and the distal tubular module <NUM> may vary, for example to increase flexibility toward the distal tip. In the embodiment shown in <FIG>, the wall thickness <NUM> of the proximal tubular module <NUM> may be the same as the wall thickness <NUM> of the distal tubular module <NUM>. In the embodiment shown in <FIG> and <FIG>, the wall thickness <NUM> of the proximal tubular module <NUM> is greater than the wall thickness <NUM> of the distal tubular module <NUM>. However, in this embodiment the inner diameters <NUM>, <NUM> of the proximal and distal tubular modules <NUM>, <NUM> remain the same while the outer diameters <NUM>, <NUM> of the proximal and distal tubular modules <NUM>, <NUM>, are different. In <FIG>, <FIG> the wall thickness of the proximal tubular module <NUM> tapers at the joint with the distal tubular module. Similarly, the wall thickness <NUM> of the distal module tapers at the joint with the proximal tubular module. The thickness of the wall can taper. For example, the wall thicknesses <NUM>, <NUM> are larger away from the joint <NUM> and can be the same or different with respect to each other. Any changes in inner diameter or outer diameter from one tubular module will incorporate a transition from one tubular module to the next which can be tapered.

Depending on the material as well as the structural requirements in terms of flexibility, the wall thickness of a tubular module at any point can vary, e.g., from about <NUM> to <NUM>, e.g., <NUM> to about <NUM>, about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. The inner diameter of a tubular module can vary, e.g., from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>, e.g., about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM> thickness. The outer diameter a tubular module can also vary, e.g., from about <NUM> to about <NUM>, e.g., including about <NUM>, about <NUM>, about <NUM> nim, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM> thickness. The wall thickness of the tubular module wall, the inner diameter and the outer diameter can each be constant throughout the length of the tubular module, or vary along the length of the tubular module.

The joint between tubular modules may be coated or covered with a jacket or a sleeve such as a polymer. <FIG> depict an embodiment in which the coating comprises two separate sections, a coating <NUM> that covers the distal end of the proximal tubular module <NUM> as well as the joint <NUM>, and a second coating <NUM> that covers or coats a distal portion of the distal tubular module <NUM>; the coatings <NUM>, <NUM>, may be the same or different. In other embodiments a single coating (i.e., either a jacket or spray coating) can be used. This jacket or sleeve further bonds the elements of the joint together, preventing the proximal tubular module <NUM> and distal tubular module <NUM> from disconnecting from each other. The entire catheter <NUM> or only a portion of the catheter <NUM>, e.g. the proximal or distal tubular modules, can be coated. The coating or jacket can provide a conduit for fluid along the length of the catheter. The coating may also be limited to cover only the joint <NUM> where two tubular modules are connected together. Alternatively, the joint can be covered with a ring to secure the joint <NUM>. As depicted schematically in <FIG> the joint may also be covered with a crimped metal that firmly covers and bonds the connected tubular modules. <FIG> shows a joint <NUM> covered with crimped metal <NUM> and <FIG> shows a joint <NUM> covered with crimped metal <NUM>.

In addition, the inner walls, i.e., lumen, of the proximal and distal tubular modules can be coated with an inner lining that both protects the tubular modules and facilitates transport of additional tools devices such as guidewires and balloons through the tubes of the catheter to distal locations. The inner lining can extend along a portion of the proximal or distal tubular modules or can extend throughout the entire length of the tubular modules.

The jacket as well as the inner lining can be made from a polymer, e.g., by enclosing the tube wall with a co-extruded polymeric tubular structure of single of multiple layers and heat shrinking the tubular structure, or coating the tube wall via a dip coating process. The polymer jacket material can be nylon, polyether block amide, PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy alkane), PET (polyethylene terephthalate) or PEEK (polyether ether ketone). Further, the distal tube portion <NUM> (or the entire length of catheter <NUM>) may be coated with a hydrophilic polymer coating to enhance lubricity and trackability. Hydrophilic polymer coatings can include, but are not limited to, polyelectrolyte and/or a non-ionic hydrophilic polymer, where the polyelectrolyte polymer can include poly(acrylamide-co-acrylic acid) salts, a poly(methacrylamide-co-acrylic acid) salts, a poly(acrylamide-co-methacrylic acid) salts, etc., and the non-ionic hydrophilic polymer may be poly(lactams), for example polyvinylpyrollidone (PVP), polyurethanes, homo- and copolymers of acrylic and methacrylic acid, polyvinyl alcohol, polyvinylethers, snapic anhydride based copolymers, polyesters, hydroxypropylcellulose, heparin, dextran, polypeptides, etc. See e.g., <CIT> and <CIT>. The coating can be applied by a dip coating process or by spraying the coating onto the tube outer and inner surfaces.

In the process of spray coating, a coating formulation is applied to the surface of the device using a nozzle apparatus. This apparatus has a chamber for containing the coating formulation and an opening in fluid connection with the chamber through which the coating formulation can be dispensed and deposited on the surface. To apply the coating formulation to the surface of the tubular modules of the catheter, the formulation is placed into the chamber of the nozzle apparatus and charged using a high voltage using a conductor. Once the coating formulation in the chamber is charged, it carries the same charge as the conductor. As a result, the formulation and conductor repel each other. This repulsive force discharges the coating formulation through the opening of the nozzle to create streams of droplets. An additional gas source can be used for atomizing the coating formulation.

One or both of the tubular modules <NUM>, <NUM> can further include a filament <NUM>. <FIG>, depict a filament <NUM> wrapped around the distal tubular module <NUM>. In <FIG>, the filament <NUM> is wrapped around the distal tubular module <NUM> in a spiral manner. <FIG> show the catheter, i.e., the tubular modules, in a straight configuration while <FIG> shows the catheter, the tubular modules, in a curved configuration. In general, the filament <NUM> is disposed on the outer surface of the distal tubular module <NUM> and encircles all or part of the distal tubular module <NUM>. The filament <NUM> proceeds in a spiral fashion around the distal tubular module <NUM> and forms a spiral structure on the outer surface of the tubular module. In certain embodiments, the spiral filament can be wrapped around the proximal tubular module. The filament may be wrapped in a clockwise or counter-clockwise manner around the tubular modules.

The filament <NUM> can be adhered to or attached to the tubular modules in variety of different ways. In one embodiment, the filament <NUM> is securely coupled to the tubular module fitting one or more bands or cover around it and the tubular module. Other implementations can include wedging, hooking, affixing, bonding or gluing the filament into or onto the tubular module. <FIG> shows bands <NUM>, <NUM> that securely fasten the filament <NUM> to the distal tubular module <NUM>. Additionally, in some embodiments, the jacket that covers one or more of the tubular modules also covers the filament <NUM> as well. This cover firmly secures the filament in place with respect to the tubular module.

A lubricious coating or film may be added over the jacket to facilitate movement of the catheter through blood vessels. The lubricious coating can be composed of, for example, silicone or hydrogel polymers or the like, such as polymer networks of a vinyl polymer, polyalkylene glycols, alkoxypolyethylene glycols or an uncrosslinked hydrogel, e.g., Polyethylene oxide (PEO).

In other embodiments such as in <FIG>, the filament <NUM> is threaded over the coating <NUM> on one or more of the tubular modules. <FIG> show a cross section view of the filament attached to the outer surface of the distal tubular module <NUM>. The cross-section view of the filament <NUM> may be circular, as illustrated in <FIG>. Alternatively, the cross-section of the filament <NUM> may have different shapes, for example, square, rectangular, triangular, hexagon, semicircular, or oblong. The filament <NUM> may be used for screwing (or unscrewing) through small tapering diameter vessels or occlusive segments within the arterial wall, for example, such as de novo plaque area and restenotic segment of the target vessel. As the filament <NUM> comes into contact with the vessel and/or occlusive segments, and torque is applied to the catheter, the filament facilitates forward motion of the catheter through intermediate vessels and plaque in order to reach the target vessel. For example, when the catheter system <NUM> is rotated, the filament <NUM> can be used to facilitate drilling or boring through a calcified atheromatous plaque. The filament <NUM> converts rotational motion into linear motion and torque into a linear force, thereby making it easier for the catheter to proceed through the blood vessels, especially in regions of comparative calcification. The filament <NUM> can also be used as a securing mechanism, such as to secure the catheter to a specified location within the blood vessels, by creating a clamping force against the walls of the blood vessels. To remove the catheter, the catheter would have to be backed-out using the same screw-like motion but in the opposite direction in order to prevent stripping the walls of the blood vessel. Because of its rounded surface, a circular cross-section minimizes damage to the arterial walls. The pitch angle of the spiral thread may remain constant. Having the spiral thread segment adherent to the outside of the module allows the pitch angle to remain constant over the length of the spiral segment.

The filament can be the same material or a different material from the tubular modules <NUM>, <NUM>. Alternatively, in some embodiments, the filament <NUM> can be made of a polymer.

The proximal tubular module <NUM> and the distal tubular module <NUM> can include at least one additional cut opening through the wall, as illustrated in <FIG> and <FIG>. The cut openings may be on the same or different tubular modules.

A first cut opening <NUM>, illustrated in <FIG>, can be positioned within the interrupted spiral. The first cut opening <NUM> may be oriented orthogonally to the longitudinal axis <NUM> of the tubular module or may be positioned at an angle relative to the longitudinal axis <NUM>. As illustrated in <FIG>, the filament <NUM> can be attached to the tubular module at the first cut opening <NUM>.

As illustrated in <FIG>, a second cut opening <NUM> may be shaped generally in the form of an "L" which is positioned at the distal end of the tubular module <NUM> near or adjacent to the crown <NUM> at which a tip section <NUM> is secured to the tubular module <NUM>. In one embodiment, the first cut opening <NUM> and the second cut opening <NUM> are located on the same tubular module. As illustrated in <FIG>, the filament <NUM> can be attached at the second cut opening <NUM>.

The walls of the cut openings, <NUM>, <NUM>, may be beveled or chamfered. The angle θ of the bevel may range from about <NUM>° to about <NUM>°, or about <NUM>° to about <NUM>° with respect to the long axis <NUM> of the tubular module. The shape of the cut openings, <NUM>, <NUM>, may vary and may be oval, square, L-shaped (See, <NUM>, <FIG>), V-shaped, curvilinear or circular.

<FIG>, <FIG> and <FIG> illustrate the invention where the distal end of the distal tubular module <NUM> has a crown <NUM>. The crown <NUM> is made from a plurality of closed, curvilinear elements which can be sinusoidal or generally waveform (meandering) in shape. In one embodiment, there may be a plurality of curvilinear elements, e.g., ranging from <NUM>-<NUM>. <FIG> show an embodiment where the tip <NUM> is attached to the distal tubular module <NUM>. The filament <NUM> is attached to the cut opening <NUM> of the distal end <NUM> of the distal tubular module <NUM>. The distal tubular module <NUM> and tip <NUM> may be covered with a jacket <NUM>. The jacket can act to secure the tip <NUM> to the distal end <NUM> of the distal tubular module <NUM>.

In one embodiment, shown in <FIG>, the distal end <NUM> of the distal tubular module <NUM> can attach to a tip <NUM>. The tip may comprise a hollow tubular body and may be conically tapered as shown in <FIG>. In addition, the hollow tubular body of the tip can be threaded. The tip <NUM> may be coated with a jacket <NUM>. <FIG> shows an illustration of a comparatively elongated tip <NUM>, while <FIG> shows an illustration of a comparatively shorter tip <NUM>. The tip may be configured with differences in tapering, durometer, rigidity, shape, length, radiopacity, profile, and composition as compared with either the catheter or the proximal or distal tubular modules. The tip can be made of a super-elastic alloy with shape memory. The shape of the tip can be set by heat treatment. For example, the tip may be made from or incorporate radiopaque materials such as gold.

As illustrated in <FIG>, due to the curvilinear structure (e.g., prongs) of the crown <NUM>, the surface area of the crown (SA1) can be greater than the surface area of the distal end of the distal tubular module (SA2). The greater surface area of the crown allows for greater surface area contact, and, therefore, binding, between the crown <NUM> and the tip <NUM>.

As depicted in <FIG>, a filament <NUM> can be wound spirally around both the proximal or distal tubular modules <NUM>, <NUM>, and also can continue to spiral around the tip <NUM>. In embodiments in which the tip is a hollow tube including threads, the filament can be fitted into the threads of the tip as shown in <FIG>. The filament <NUM> may proceed around all or only a portion of the tip <NUM>. The filament may be wound around the modules in a clockwise or counter-clockwise spiral manner. In other embodiments, the tip may be fabricated with a threaded structure of its own. The filament of the tip may also be covered with a jacket.

In another embodiment, shown in <FIG>, a re-entry tip can be coupled to the distal end of the distal tubular module with or without directly engaging the prongs of the crown <NUM>. further description of catheter re-entry is found in commonly owned and assigned <CIT>, entitled "Vascular Re-entry Catheter. When used with a re-entry tip, the modular catheter can be used in procedures involving re-entry into the true lumen after the creation of a dissection plane.

Examples of re-entry tips are shown in <FIG> is a re-entry tip <NUM> having a smooth surface and two wings disposed on either side of the re-entry tip. <FIG> is a re-entry tip <NUM> having divots in its surface around the entire diameter of the tip. <FIG> is a re-entry tip <NUM> having divots in its surface around the entire diameter of the tip and two wings disposed on either side of the re-entry tip. <FIG> <NUM> is a re-entry tip having a smooth surface and no wings.

As shown in <FIG>, the modular catheter system <NUM> can further comprise at least one side port <NUM>. Some embodiments, as shown in <FIG> and <FIG>, have two side portsl900a, 1900b. More than two side ports can be used. In the embodiments having more than one side port, the side ports can all be aligned linearly down the length of the catheter system <NUM>. In other embodiments, the side ports can be aligned around the diameter of the catheter system <NUM>. The side ports can be evenly spaced down the length of the catheter system <NUM>, or they can be spaced at specific locations. In another embodiment, the side ports are disposed only on the distal tubular module <NUM>.

Referring to <FIG>, side ports 1900a and 1900b can be positioned radially offset, between about <NUM>° apart from each other, e.g., about <NUM>° (± <NUM>°). A re-entry tip <NUM> includes wings <NUM>, <NUM> also spaced apart by approximately <NUM>°. In general, the radial displacement of the side ports relative to the wings may range from about <NUM>° to <NUM>°, e.g., <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>° and <NUM>°. In one embodiment, the positions of the side ports may be radially offset from the wings at about <NUM>°. In this way, when the two wings <NUM> and <NUM> are positioned in a stable configuration in the subintimal space of an artery, port 1900a can be facing either toward or opposing the true lumen of the artery, and the port 1900b can face the opposite side.

The side ports may be symmetrical in shape and can be circular, semi-circular, ovoid, semi-ovoid, rectangular or semi-rectangular. The side ports may have the same shape and size (i.e., surface area) or can be different from each other and are configured to allow for passage of a re-entry wire or another medical device through the ports. The dimensions of the port may be adjusted to accommodate different types of medical devices or wires, e.g., with diameters ranging from about <NUM> to about <NUM>. The distal tube portion <NUM> can contain more than two exit ports, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. n ports along its length direction and radially distributed as desired.

The side port may be beveled. The beveled configuration of the side port can facilitate a re-entry wire with a bent tip to smoothly exit and regress from the side port. The angle θ of the bevel may range from about <NUM>° to about <NUM>°, including, <NUM>° to about <NUM>°, about <NUM>° to about <NUM>°, or <NUM>° to about <NUM>°.

In one embodiment, at least two radiopaque markers and positioned along distal tubular portion <NUM> for aiding radiographic visualization of the positioning of the catheter <NUM> in the vascular lumen. The markers can include a radiopaque material, such as metallic platinum, platinum-iridium, Ta, gold, etc., in the form of wire coil or band, vapor deposition deposits, as well as radiopaque powders or fillers, e.g., barium sulfate, bismuth trioxide, bismuth sub carbonate, etc., embedded or encapsulated in a polymer matrix. Alternatively, the markers can be made from radiopaque polymers, such as radiopaque polyurethane. The markers can be in the form of bands to encircle the outer sheath of the distal tubular portion.

The radiopaque markers configured as bands can be used to facilitate determination of the positions of the side ports while the distal tube portion <NUM> is maneuvered in a subject's anatomy. The markers can also be configured as a partial band or patch which forms specific alignment with a corresponding side port. For example, one marker can be axially aligned with side port 1900a, whereas a second marker can be axially aligned with side port 1900b. Thus, like the radially opposite configuration of the side ports 1900a and 1900b, the markers are also radially opposite to each other. In this manner, visualization of the markers can be used to determine the orientation of the respective side ports. The markers can be configured in different shapes, e.g., partial circumferential bands, or any other desired shapes, to facilitate determination of orientation of the ports.

The markers can also be configured as surface patches that enclose the circumferences of the respective side ports 1900a and 1900b. In such an embodiment, the marker positions that can be visualized directly correspond to the side port positions.

The markers should have sufficient size and suitable configuration/construction (e.g., the type of radiopaque material, load amount of radiopaque material, etc.) such that they can be visualized with the proper radiographic aid.

The variable flexibility of the sections of the tubular modules also facilitates surgical procedures in which side-branch access is required or where tortuous vasculature is encountered such as in the central nervous system. Given the ability to use a wide variety of combinations from the base tube's material mechanical properties, the tubing dimensions (OD/ID), wall thickness, cut tubing's mechanical properties resulting from the cut pattern along the tube's (material composition , UTS, % Elongation modulus of Elasticity, and other combinations of material and mechanical properties (UTS, formulas defining cut pitch angle, cut width, helical cut arc length and uncut helical space between next helical arc cut), all enable the designer to tailor a variety of mechanical properties defined throughout the running length of the cut tube. Such resulting properties such as stiffness, flexibility and using the shape memory properties define a preset curvilinear shape are programmable and changeable.

Additionally, such an induced shape memory form would require a greater force to straighten or diminish and maintain via a resistive load force along the cut and shape treated portion of the distal tubular segment, to orient the shape set portion of the tube to revert back into a straight linear concentric coaxial configuration, which would enable the catheter to be advanced to the vascular target.

Such variables assembled together, to create a wide variety of structural shape combinations of tubular modules. These structural shapes can easily be temporarily diminished inline by advancing the tubular modules over a wire track, e.g., a guidewire, which exhibits mechanical properties of deformation that exceed the curvilinear shape's spring constant. This temporary deformation enables advancement of the catheter, the tubular modules, over the guidewire through the vascular anatomy. Simply put, the spring constant of the shaped curve portion is less than that of the wire segment it is tracking over. Once the retaining guidewire segment's spring constant is less than that of the set curvilinear shape, the cut shaped tube segment will revert back to its preset shape, unless acted upon by an additional other external forces or vascular confinement.

The distal modules of the present invention can include portions that bend or hook or are set in-place in a curvilinear shape through the application of shape memory. As noted above, super-elastic alloys including Nitinol have this property, which can be modified by heating. <FIG> depict a side view and an end view, respectively of a distal end of a catheter according to the present invention that includes this feature. As shown in the side view, a portion of a distal tubular module <NUM> includes at its distal end a curvilinear section <NUM> that bends. The bend can be at least one of: a curve, a sinusoidal curve, a non-linear section, an angulation, a peak, a valley, a squiggle, curvilinear, and helical. The bend can have a variable stiffness. The bend can have a stiffness coefficient greater than the remaining portion of the elongated member.

The curvilinear section can bend from about <NUM>° to about <NUM>° with respect to the longitudinal axis (L, <FIG>) of the tubular module. The curvilinear shapes of the section can vary and include, flush, simple curves, complex curves, reverse curves or double curves. The length of the curvilinear section can vary and may encompass only a portion or the entire length of the tubular module. In the embodiment shown in <FIG>, the curvilinear section <NUM> assumes the <NUM>° unless a force, e.g., a guidewire, is applied to straighten or otherwise alter its configuration. Force may be applied through a variety of means, such as a guidewire which is inserted into the lumen of the tubular module and is co-axial with the lumen of the tubular module. The end view in <FIG> shows a lumen <NUM> of the distal tubular module. This cross-section of the lumen remains constant during bending of the curvilinear section <NUM>. This constant cross-sectional lumen facilitates passage of wires and other devices through the vasculature.

The catheter can include a guidewire which can be passed through the lumen of the tubular modules. The tubular modules can be passed over the guidewire into an artery. Guidewires are typically comparatively thin, having a diameter in the order of about <NUM> to <NUM>. Guidewires are capable of transmitting rotation from the proximal end of the guidewire to the distal end of the guidewire. This transmission allows the physician to controllably steer the guidewire through the branches of the patient's arteries and manipulate the catheter to the intended target site in the coronary artery. Additionally, the distal end of the guidewire should be sufficiently flexible to allow the distal portion of the guidewire to pass through sharply curved, tortuous coronary anatomy.

Among the common guidewire configurations used in angioplasty is the type of guidewire illustrated in <CIT>. Such a wire includes an elongate flexible shaft, typically formed from stainless steel, having a tapered distal portion and a helical coil mounted to and about the tapered distal portion. The generally tapering distal portion of the shaft acts as a core for the coil and results in a guidewire having a distal portion of increasing flexibility that is adapted to follow the contours of the vascular anatomy while still being capable of transmitting rotation from the proximal end of the guidewire to the distal end so that the physician can controllably steer the guidewire through the patient's blood vessels. The characteristics of the guidewire are affected significantly by the details of construction as the distal tip of the guidewire. For example, in one type of tip construction, the tapering core wire extends fully through the helical coil to the distal tip of the coil and is attached directly to a smoothly rounded tip weld at the distal tip of the coil. Such a construction typically results in a relatively stiff tip suited particularly for use when attempting to push the guidewire through a tight stenosis. In addition to a high degree of column strength, such a tip also displays excellent torsional characteristics.

In another type of tip construction, the tapered core wire terminates short of the tip weld. It is common in such a construction to attach a very thin metallic ribbon at one (proximal) end to the core wire and at its other (distal) end to the tip weld. The ribbon serves as a safety element to maintain the connection between the core wire and the distal tip weld in the event of coil breakage. It also serves to retain a bend formed in the ribbon to maintain the tip in a bent configuration as is desirable when manipulating and steering the guidewire. Additionally, by terminating the core wire short of the tip weld, the segment of the helical coil between the distal end of the core wire and the tip weld is very flexible and floppy. The floppy tip is desirable in situations where the vasculature is highly tortuous and in which the guidewire must be capable of conforming to and following the tortuous anatomy with minimal trauma to the blood vessel. In another type of tip construction, the distal-most segment of the core wire is hammered flat (flatdropped) so as to serve the same function as the shaping ribbon but as an integral unitary piece with the core wire. The tip of the flat dropped segment is attached to the tip weld. Guidewires are well known in the art and the appropriate choice of a guidewire for use the catheter of the present invention can be made by a medical professional, such as an interventional cardiologist or interventional radiologist.

<FIG> depict a side view and end view of another embodiment of a distal end of a catheter according to the present invention. In this embodiment, a distal tubular module <NUM> includes at its distal end a curvilinear section <NUM> that naturally assumes a <NUM>° bend from the point at which it is connects to the remainder of the distal tubular module (i.e., the horizontal axis) up to a tip <NUM>. The curvilinear section assumes the <NUM>° bend unless a force is applied to straighten or otherwise alter its configuration. The end view in <FIG> shows a lumen <NUM> of the distal tubular module. This lumen can maintain a constant cross-section in distal tubular module lumen is maintained within the curvilinear section <NUM>.

<FIG> shows a side view of still another embodiment of a distal end of a catheter according to the present invention. In this embodiment, the curvilinear section <NUM> of a distal tubule module <NUM> bends still further, to approximately <NUM>°, such that the tip <NUM> point toward the distal tubular module and aligns approximately parallel with the longitudinal axis, L, of the distal tubular module.

<FIG> shows three parts of a sequence in which the tubular modules, include a curvilinear section together with a guidewire. Any conventional guidewire may be used with the present invention. For example, the central core of the guidewire may be formed from Stainless steel, Durasteel™ or nitinol/Lastinite®. The guidewire may be covered with a polymer sleeve or a coil-spring tip and coated with a lubricious coating.

<FIG> is a cross-sectional view illustrating a distal tubular module having a curvilinear section <NUM> that is straightened-out by passing the distal tubular module <NUM> over a guidewire <NUM> extending through the tubular module <NUM> and tip <NUM>. As shown, the guidewire <NUM> extends through the end portion of the distal tubular module <NUM>, passing through the shape-memory, curvilinear section <NUM>, past the tip <NUM> of the tubular module. In this position, the guidewire <NUM> keeps the curvilinear section <NUM> aligned or straight with respect to the longitudinal axis (L) of the distal tubular module <NUM> and prevents the curvilinear section from bending in accordance with its shape memory. In other words, the spring constant of the curvilinear section <NUM> is less than that of the spring constant of the guidewire <NUM> segment that the distal tubular module <NUM> is tracking over. If the spring constant of the retaining guidewire <NUM> segment is less than the spring constant of the curvilinear section <NUM>, the curvilinear section <NUM> will revert back to its preset shape, unless acted upon by an additional other external forces or vascular confinement.

In <FIG>, the guidewire <NUM> has been withdrawn in the leftward direction (as shown by the arrow) from the tip <NUM> and a distance (L1) within the preset curvilinear section <NUM> of the distal tubular module <NUM>. As shown in <FIG>, as the guidewire <NUM> is withdrawn, the preset curvilinear section <NUM> begins to bend and assume its preset shape as discussed above.

In <FIG>, the guidewire <NUM> has been withdrawn still further from the position shown in <FIG>, i.e., L2>L1, within the curvilinear section <NUM>. As a result, the curvilinear section <NUM> continues to bend in accordance with its shape memory such that the angle between the direction in which the tip <NUM> faces and the longitudinal axis, L, of the distal tubular module <NUM> (Ψ) is greater than <NUM>°. The range of bending ranges from about <NUM>° to about <NUM>° with respect to the longitudinal axis, L. In this embodiment, the distal end of the distal tubular module in this position is configured in the shape of a "Shepherd's Hook" and is better adapted, in this configuration, to access side-branches in the arterial system or for access into tortuous vasculature.

<FIG> shows an example of the catheter and distal tubular module with a curvilinear section with shape memory as it can be applied for side-branch artery access. In the Figure, a main arterial branch <NUM> and a side-branch artery <NUM> which joins to and branches-off from the main artery <NUM> are shown. The distal end of a catheter, including a distal tubular module <NUM>, together with a preset, curvilinear section <NUM> and tip <NUM> are shown. In the Figure, the guidewire <NUM> has been withdrawn from the curvilinear section <NUM>, allowing the curvilinear section to bend to about <NUM>° with respect to the longitudinal axis of the tubular module (see, L, <FIG>, supra.

As the catheter, which includes the distal tubular module <NUM> is moved laterally in the artery the curvilinear section <NUM> can enter the side branch <NUM>. Note, a torqueing force may be applied to the catheter by rotating the hub which can rotate the proximal and distal tubular modules about the central axis.

<FIG> shows a cross-sectional view of an arterial system which comprises a main vessel <NUM> together with a single side branch artery (also referred to as a side branch) <NUM>. In the example shown, the diameter of the main artery <NUM> is greater than the diameter of the first side-branch <NUM>. A distal tubular module <NUM> is shown positioned in the artery <NUM> where the distal tubular module extends past the side branch artery <NUM>. The guidewire <NUM> extends past the end of the distal tubular module <NUM> and the tip <NUM>. The guidewire <NUM> includes a tapered section <NUM>. As discussed above, the guidewire <NUM> straightens-out the pre-set, curvilinear section <NUM> of the distal tubular module <NUM>.

<FIG> shows the guidewire <NUM> partially withdrawn from the distal tubular module <NUM>, allowing the curvilinear section <NUM> to bend. The tip <NUM> and the tapered end <NUM> of the guidewire <NUM> reposition in accordance with the bending of the curvilinear section <NUM> and enter into the side branch of the artery <NUM> or position the tip <NUM> allowing for entry into the side branch <NUM>.

In <FIG>, the guidewire <NUM> is withdrawn further from the distal tubular module <NUM>. The tip <NUM> and the tapered end of the guidewire <NUM> are aligned with the axis of the side branch <NUM>.

In <FIG>, the tapered end of the guidewire <NUM> is extended past the tip <NUM> into the side branch <NUM>. Then, in <FIG>, the distal tubular module <NUM> is advanced over the guidewire <NUM> down through the side branch <NUM>.

<FIG> shows another method for enabling access to arterial side branches. As depicted, a distal tubular module <NUM>, including a preset, curvilinear section <NUM> and tip <NUM> are positioned in a main artery <NUM> with a guidewire having been withdrawn. The preset, curvilinear section <NUM> and tip <NUM> are positioned past (in the forward movement direction) the junction of the main artery <NUM> with a side branch <NUM>. Because of shape memory in the preset curvilinear section <NUM>, this section and the tip are in shown in a bent or Shepherd's Hook position. In the example shown, the tip is bent <NUM>° in the reverse movement direction, parallel to the longitudinal axis. The preset bend can also be at other angles (e.g., <NUM>°, <NUM>°, <NUM>°, etc.). From this position, as the distal tubular module <NUM> is withdrawn, a torque force <NUM> can be applied to rotate the distal tubular module <NUM> clockwise or counterclockwise. The distal tubular module <NUM> can then be inserted into the side branch <NUM>.

<FIG> shows the distal tubular module <NUM> and tip <NUM> having entered further into the side branch <NUM> from the position shown in <FIG>. In <FIG> the tip approaches alignment with the axis of the side branch <NUM>.

<FIG> shows the continued advancement of the distal tubular module <NUM> through a first side branch <NUM>. A guidewire <NUM> can be used to straighten the curvilinear section <NUM> to enable the catheter to proceed through the lumen of the side branch <NUM>. Because of the engineered flexibility of the distal tubular module, the distal tubular modules can bend to accommodate sharp turning angles <NUM>.

In short, in both single side branch access methods, the preset, curvilinear section of the distal tubular module is used in the manner of a hook to create a secure anchor for advancement into side branches, ultimately allowing advancement of the catheter through multiple arterial vessel and side branches.

<FIG> shows an arterial system including a main artery <NUM>, a side branch artery <NUM>, and a secondary side branch <NUM> coming off of the side branch <NUM>. A path <NUM> for advancing a catheter through the main artery <NUM> and the two side branches <NUM>, <NUM> is shown. <FIG> shows a distal tubular module <NUM> extended through a side branch <NUM> in a manner discussed above with respect to <FIG> and <FIG>. The tip <NUM> and the tapered end of the guidewire <NUM> extend at an approximately right angle to the axis of the second branch <NUM>. In <FIG>, the guidewire <NUM> has been partially withdrawn and a torqueing force, <NUM>, <NUM>, has been applied to the distal tubular module <NUM>. Because of the construction of the catheter, the torque is transmitted to the tip <NUM> and curvilinear portions <NUM> (as shown by the curved arrows <NUM>). The torqueing force angles the tip <NUM> away from the axis of the first branch <NUM>. A combination of torqueing force and lateral movement enable the tip <NUM> to access second side branch <NUM> as shown in <FIG>. In <FIG>, the guidewire <NUM> is advanced through the distal tubular module <NUM> and tip <NUM>, allowing the distal tubular module <NUM> to be transported over the path defined by the guidewire <NUM>.

Because of the modular construction of the catheter system according to the present invention, a family of microcatheters can be created by varying the distal tubular module of the catheter system for use in different procedures. A microcatheter is typically a single-lumen device that can be loaded on a guidewire in order to track it to the target lesion. The typical outer diameter (OD) ranges from about <NUM> on the proximal portion of the shaft to about <NUM> on the distal portion or tip of the shaft. The internal diameter of the lumen of the distal tubular module can vary and when used as a microcatheter can taper. The trackability and pushability of the distal tubular module can be varied as described above. The distal tubular module can be designed to address specific anatomical challenges, such as for use in antegrade procedures or retrograde procedures, for use in peripheral vascular access procedures, or for use as a re-entry catheter. The distal tubular module and the proximal tubular module can be preassembled with the proximal tubular module being attached to one of a variety of distal tubular modules. Or the distal tubular module and the proximal tubular module can be separate and assembled immediately prior to use.

The design of the distal tubular module can be varied such as by using different materials for fabrication. The in-line stacked variable wall thickness can also be varied, such as by simple inline stepped reduction in outer diameter while maintaining a constant inner diameter, by machining or grinding the tubular module material to vary the wall thickness along the length of the tubular module, or by laser cutting, ablating, machining, or grinding the tubular module material to create specific design features along the tubular module surface, such as a screw thread design carved out of the tubular module material at a specific location or along a defined length. The design of the distal tubular module <NUM> can also be varied through the use of stacked interrupted spiral-cut patterns along the length of the tubular module. These interrupted spiral-cut patterns formula variables could include the cut pitch angle, laser cut path width, or stacked variable cut patterns along the length of the tubular module, for example having a formula for interrupted spiral-cut pattern of cut and non-cut degrees along the helical cut.

Another specific example of a use for the modular catheter system would be for creating a microcatheter device. Such micro catheter could comprise a base micro catheter as one of the tubular modules. This base microcatheter could be used for an antegrade approach, having tight lesion access and backup wire support. The second tubular module can be one of a variety of microcatheters. These devices could have peripheral vascular and neuro vascular arterial access and can be used in many disease management applications and should not be limited to only the example provided herewith.

The proximal tubular module and the distal tubular module can have different flexibility, kinkability, torque to failure, torqueability, trackability, pushability, crossability, and rotational response. A variety of different tests are available for testing flexibility, kinkability, torque to failure, torqueability, trackability, pushability, crossability, and rotational response. Various standard tests for these properties known in the art are disclosed in, for example, http://www. protomedlabs. com/medical-device-testing/catheter-testing-functional-performance.

The proximal tubular module and the distal tubular module can have the same flexibility or different flexibilities. Flexibility is the quality of bending without breaking. The flexibility of the tubular module is dependent on the material used, the interrupted spiral pattern, the wall thickness, the inner diameter and the outer diameter, and other variables. Flexibility can be determined by one of the following testing methods. One method of testing flexibility uses a proximal load cell to measure the ability of the device to advance and withdraw, with no loss of function or damage to the tortuous anatomy, over a specific bend angle. Alternatively, a roller system can be used to determine the smallest radius of curvature that the device can withstand without kinking. Additionally, tests can be performed by a cantilever beam to measure force and bending angle by calculating F = [M x (%SR)] / (S x <NUM>) with angularity at <NUM>° where F = flexibility, M = total bending moment, %SR = scale reading average, and S = span length. Another method of testing flexibility is to use one- and four-point bending tests to evaluate flexibility under displacement control using a ZWICK <NUM> testing machine which detects the force F and the bending deflection f when one end of a device is grilled and the other end pressed with a plate moving at a constant speed. The highest measured data describes the flexibility as determined by the equation E x I = (F x L<NUM>) / (<NUM> x f) (Nmm<NUM>) where I = moment of inertia, E = Young modulus, L = bending length, f = bending deflection, and F = point force and E x I = flexibility.

The proximal tubular member and the distal tubular member can have the same or different torque to failure or torque to break. Torque to failure is the amount of twisting or rotational force the tubular member can withstand before a plastic deformation of the catheter components, a fracture or break occurs. One method for testing torque to failure is through the use of proximal and distal torque sensors which measure the amount of torque and the number of revolutions until device failure by rotating the device at a more proximal location and fixing the distal end while the device is routed through tortuous anatomy. Another testing method for calculating torque to failure is by testing torque strength immediately following submersion in <NUM> ± <NUM>° C water for a set period of time. With a guidewire in place, the device can be inserted into a compatible guiding catheter which is constrained in a two dimensional shape to replicate access into the coronary anatomy until the distal most <NUM> of the catheter is exposed beyond the guiding tip and is attached to a torque gauge to prevent rotation. The remainder of the catheter body is rotated in <NUM>° increments until distortion, failure, breaks, fractures, kinks, or other damage occurs along the catheter or at the catheter tip, or for a set number of rotations.

The proximal tubular member and the distal tubular member can have the same or different torqueability. Torqueability is the amount of torque, or rotation, lost from one end of the tubular module to the other end of the tubular module when a rotational force is exerted on one end. One method for testing torqueability is by using a proximal and distal torque sensor to measure the amount of torque transmitted through the device by rotating the device at a more proximal location and fixing the distal end while the device is routed through tortuous anatomy. Another method for testing torqueability is by using an artery simulating device for PTCA training, such as the PTCA trainer, T/N: T001821-<NUM>, designed by Shinsuke Nanto, M. , which simulates a clinical tortuous path. An indicator attached to the catheter tip and inserted through the hole of a dial. The catheter body is connected to a rotator, for example T/N: T001923, and rotated clockwise in <NUM>° increments to <NUM>°. The angle measured by dial attached to the indicator on the catheter tip is used to calculate the ratio of the angle of rotation of the body to the angle of rotation of the tip, which corresponds with the amount of torque lost during rotation.

The proximal tubular module and the distal tubular module can have the same trackability or different trackabilities. One method for testing trackability is to use a proximal load cell to measure the force to advance the device through a tortous anatomy with or without the aid of a guiding accessory.

The proximal tubular module and the distal tubular module can have the same or different pushability. One method for testing pushability is to use a proximal and distal load cell to measure the amount of force the distal tip of the device sees when a known force is being applied to on the proximal end.

The proximal tubular module and the distal tubular module can have the same or different crossability. One method for testing crossability is to use a proximal load cell to measure the ability of the catheter device to advance and withdraw over a specific lesion site without loss of function or damage to the tortuous anatomy. Additionally, a roller system can determine the worst lesion that the device can withstand without damage.

The proximal tubular module and the distal tubular module can have the same or different rotational response. One method for testing rotational response is by using proximal and distal rotation encoders to measure the amount of rotation transmitted through the device by rotating the device at a more proximal location and keeping the distal end free while the device is routed through tortuous anatomy.

Claim 1:
A catheter comprising, at least one proximal tubular module (<NUM>) and a distal tubular module (<NUM>),
each of the tubular modules having at least one section with spiral cuts, each pair of adjacent tubular modules are coupled by a joint (<NUM>),
the joint comprising:
(a) at least one snap-fit connector (<NUM>) on a first tubular module and a snap-fit acceptor (<NUM>) positioned on the adjacent tubular module, the snap-fit connector being elastically deformable when engaged, and at least one stabilizing element, including a tongue element (<NUM>, <NUM>) positioned on the first tubular module or the adjacent tubular module, and a groove element (<NUM>, <NUM>) positioned on the opposite, first tubular module or the opposite, adjacent tubular module, or
(b) an interlocking shape having a plurality of protruding sections (<NUM>, <NUM>) and receiving sections (<NUM>, <NUM>) that mate with the protruding sections, each of the adjacent tubular modules in the pair having one or more of the plurality of protruding sections and the plurality of receiving sections,
characterized in that
the distal end of the distal tubular module has a crown comprising a plurality of curvilinear elements (<NUM>), especially curvilinear elements that are sinusoidal in shape,
preferably <NUM>-<NUM> of said curvilinear elements.