Patent ID: 12201792

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings,FIG.1is an elevational view of one exemplary embodiment of a guidewire10according to the present invention. The guidewire10is comprised of a machined composite drawn-filled tube12supporting a helical or coil spring14. The drawn-filled tube12has an inner core wire16surrounded or jacketed by an outer sheath18. The core wire16is preferably made of nitinol being a superelastic nickel-titanium alloy wire comprising, for example, a composition in the range of from about 54 atomic % nickel:about 46 atomic % titanium to about 57 atomic % nickel:about 43 atomic % titanium. The outer sheath18is preferably made of stainless steel, for example 304 stainless steel. The coil spring14is also made of stainless steel, preferably 304 stainless steel. The guidewire10has a length ranging from about 50 cm to about 350 cm.

The core wire16extends along a longitudinal axis A-A from a core wire proximal portion16A having a proximal end16B to a core wire distal portion16C having a distal end16D. In this exemplary embodiment, the inner core wire16has a substantially constant diameter20ranging from about 0.004″ to about 0.030″ extending from the core wire proximal end163to the distal end16D. An atraumatic distal tip22is provided at the core wire distal end16D. The atraumatic tip22is made of stainless steel, preferably 304 stainless steel.

The outer sheath18is comprised of an outer sheath proximal portion18A having a proximal end18B. The outer sheath has a substantially constant thickness of from about 0.002″ to about 0.008″ so that the outer diameter24of the outer sheath jacketing the inner core wire ranges from about 0.008″ to about 0.038″ extending along the length of the proximal portion18A. At the cross-section indicated at26, the outer sheath18transitions to a tapered portion18C that gradually reduced in cross-sectional diameter as it extends distally and downwardly toward the longitudinal axis A-A and the outer surface16E of the inner core wire16. The outer sheath18terminates or tapers out at the outer surface16E of the core wire16at a location that is proximal the atraumatic tip22.

The atraumatic tip can be a separate member that is secured to the core wire16at its distal end16D or, preferably, the tip22is a portion of the outer sheath18supported on the core wire16. The atraumatic tip has a beveled surface22A that widens in cross-section from the core wire16to an intermediate cylindrical portion22B. A sloped portion22C extends distally and downwardly from the intermediate cylindrical portion22B toward the core wire distal end16D. If desired, the sloped portion22C can be curved to further enhance the atraumatic shape of the tip22. The intermediate cylindrical portion22B of the tip22comprising the outer sheath18jacketing the inner core wire16has an outer diameter that is substantially the same as the outer diameter24of the outer sheath proximal portion18A ranging from about 0.008″ to about 0.038″.

The proximal end14A of the coil spring14is connected to the tapered portion18C of the outer sheath18. This connection is distal the outer sheath proximal portion18A having the substantially constant outer diameter24. The opposite distal end14B of the coil spring14is connected to the atraumatic tip22, preferably to its beveled surface22A. The connections of the coil spring proximal end14A to the tapered portion18C of the outer sheath18and of the coil spring distal end14B to the beveled portion22A of the atraumatic tip22are made as a laser welder, a braze, or using a solder, and the like.

FIG.2illustrates a drawn-filled tube50that is useful for manufacturing the guidewire10shown inFIG.1. The drawn-filled tube50is a composite of the core wire16jacketed by the outer sheath18. The core wire16has the substantially constant diameter20ranging from about 0.004″ to about 0.030″ extending from the core wire proximal end16B to the core wire distal end16D. The outer sheath18has the substantially constant thickness ranging from about 0.002″ to about 0.008″. That way, the outer diameter24of the outer sheath18jacketing the inner core wire ranges from about 0.008″ to about 0.038″ extending from the outer sheath proximal end18B to an outer sheath distal end18D. The drawn-filled tube50is then subjected to a manufacturing process, for example a cam grinding process to remove the major portion52of the outer sheath18indicated by dashed lines54and the minor portion56indicated by the dashed lines58. The resulting machined drawn-filled tube12comprising the outer sheath18jacketing the core wire16has the structure shown inFIG.1. It is noted that the material of the outer sheath18bounded by dashed lines54and58forms the atraumatic tip22.

FIG.3illustrates the guidewire10shown inFIG.1, but with the distal portion16C of the core wire16having been shape-set into a desired curved configuration. Shape setting the nitinol distal portion16C or modifying the nitinol super-elastic properties locally is done in an annealing step where the nitinol is heated to a temperature of from about 300° C. to about 600° C. for a period of time ranging from about five minutes to about two hours. This annealing step is preferably performed prior to connecting the coil spring14to the machined drawn-filled tube12. Alternately, the coil spring14is attached to the machined drawn-filled tube12prior to the annealing step. The guidewire110has a length ranging from about 50 cm to about 350 cm.

FIG.4Ashows a second embodiment of an exemplary guidewire110according to the present invention. The guidewire110is comprised of a composite drawn-filled tube112supporting a helical or coil spring114. As is the case with the guidewire10illustrated inFIGS.1and2, the drawn-filled tube112is comprised of a core wire116surrounded or jacketed by an outer sheath118. The core wire116is preferably made of nitinol being a superelastic nickel-titanium alloy wire comprising, for example, a composition in the range of from about 54 atomic % nickel:about 46 atomic % titanium to about 57 atomic % nickel:about 43 atomic % titanium. The outer sheath118and coil spring114are made of stainless steel, preferably 304 stainless steel.

The core wire116extends along a longitudinal axis B-B from a core wire proximal portion116A having a proximal end116B to a core wire distal portion116C having a distal end116D. In this exemplary embodiment, the core wire116has a substantially constant first outer diameter122extending from the core wire proximal end116B to a first transition indicated at124. An exemplary first outer diameter ranges from about 0.004″ to about 0.030″.

A first tapered portion116E extends distally and downwardly towards the longitudinal axis B-B from the first transition124to a second transition indicated at126. A core wire intermediate portion116F begins at the second transition126. The intermediate portion116F has a substantially constant second outer diameter128, the second diameter128being less than the first diameter122, and extends distally from the second transition126to a third transition indicated at130. An exemplary second outer diameter122is of about 0.010±0.0005 inches. A second tapered portion116G extends distally and downwardly towards the longitudinal axis B-B from the third transition130to a fourth transition indicated at132where the core wire distal portion1160begins. The distal portion116C has a substantially constant third outer diameter134, the third diameter134being less than the second outer diameter128. An exemplary third outer diameter is about 0.0075 inches. The core wire distal portion116C extends distally to the distal end116D.

A distal atraumatic tip136is provided at the core wire distal end116D. As previously described with respect to the atraumatic tip22inFIGS.1to3, the tip136is preferably formed from the 304 stainless steel material comprising the outer sheath118.

The outer sheath118is comprised of an outer sheath proximal portion118A having a proximal end118B. The outer sheath proximal portion118B has a substantially constant thickness of from about 0.002″ to about 0.008″ and a substantially constant fourth outer diameter138extending distally to a fifth transition indicated at140so that the outer diameter138of the outer sheath118jacketing the inner core wire116ranges from about 0.008″ to about 0.038″ extending along the length of the proximal portion118A. At the cross-section indicated at140, the outer sheath118transitions to a tapered portion118C that gradually reduces in cross-sectional diameter as it extends distally and downwardly toward the longitudinal axis B-B to terminate or taper out at the outer surface of the intermediate portion116F of the core wire116, proximal the atraumatic tip136.

It will be readily apparent to those skilled in the art that while the core wire116comprising the drawn-filled tube112is shown having three constant diameter portions116A,116F and116C, and two intermediate tapered portions116E and116G, that is for the sake of example only. Depending on the functional requirements of a particular guidewire design, there can be a greater or lesser number of constant diameter portions separated from each other by an intermediate tapered portion.

Further, while the tapered outer sheath portion118C is shown terminating or tapering out at the intermediate constant diameter core wire portion116F, that is exemplary. In another embodiment, the tapered outer sheath portion118C tapers out at the distal constant diameter core wire portion116C.

Moreover, while the first transition124of the core wire116and the fifth transition140of the sheath118are shown as coinciding inFIG.4A, that is also by way of example. In other embodiments, the fifth transition140can occur either proximal or distal the first transition124.

As is the case with the atraumatic tip20of the guidewire10shown inFIGS.1and2, the atraumatic tip136for guidewire110can be a separate member that is secured to the core wire116at its distal end116D or, preferably, the tip136is a portion of the outer sheath118supported on the core wire116. The atraumatic tip has a beveled surface136A that widens in cross-section from the core wire116to an intermediate cylindrical portion136B having a diameter that is less than the second outer diameter122of the outer sheath proximal portion118A. A sloped portion136C extends distally and downwardly toward the core wire distal end116D. If desired, the sloped portion136C of tip can be curved to further enhance the atraumatic shape of the tip136. In an alternate embodiment, the intermediate cylindrical portion136B has an outer diameter that is the same as the fourth outer diameter138of the outer sheath portion118B.

The proximal end114A of the coil spring114is connected to the tapered portion118C of the outer sheath118. This connection is distal to the outer sheath proximal portion118A having the substantially constant second outer diameter122. The opposite distal end114B of the coil spring114is connected to the atraumatic tip136, preferably to the beveled surface136A. The connections of the coil spring proximal end114A to the tapered portion118C of the outer sheath118and to the beveled portion136A of the atraumatic tip136are made as a laser welder, a braze, or using a solder.

FIG.4Bis an enlarged view of an alternate embodiment of the indicated distal portion of the guidewire110shown inFIG.4A.FIG.5is a cress-sectional view taken along line5-5ofFIG.4Aand illustrating that the distal portion116C of the nitinol core wire116does not have the substantially constant third outer diameter134. Instead, the distal portion116C has a generally oval cress-section aligned perpendicular to the longitudinal axis B-B. In this embodiment, the distal portion116C comprises opposed substantially parallel planar surfaces150and152extending from the fourth transition indicated at132to the atraumatic tip136. The planar surfaces150,152are joined to each ether by opposed radiused or curved surfaces154and156. This shape for the distal portion116C of the nitinol core wire116can be set using a fluidized bath or air furnace, and the like, and enhances the stiffness of the nitinol core wire116adjacent to the atraumatic tip136.

FIG.5further illustrates that a polymeric coating160is provided on the proximal and tapered portions118A and118C of the outer sheath118. While not shown in the drawing, the polymer coating160also preferably covers the coil spring114. Polyurethane is a preferred material for the coating160.

FIG.6is an elevational view of the guidewire110illustrated inFIGS.4A and4B, but with the stainless steel coil spring114replaced with two coil springs115and117. Preferably, the proximal coil spring115is of a non-radiopaque material, for example, stainless steel, and the distal coil spring117is of a radiopaque material, for example titanium. At their respective distal and proximal ends, the coil springs115,117either overlap each other, are interwound or soldered together. Further, the connection between the coil springs115,117is either supported by a solder or like material that also contacts the core wire116, or the connection between the springs is unsupported. In any event, the radiopaque coil spring117helps a physician visualize the distal portion of the guidewire110as it is moved through the vasculature of a patient.

Thus, various embodiments of guidewires made from a drawn-filled tube comprising a stainless steel cuter sheath jacketing a nitinol core wire are described. The proximal end of the guidewire with the nitinol/stainless steel drawn-filled tube composite is stiffer than the nitinol distal portion due to the relative stiffness of stainless steel. The stiffness of the guidewire can be tailored by changing the ratio of the thickness of the stainless steel outer sheath to that of the nitinol core wire. This thickness ratio can be controlled by grinding or cold working when the drawn-filled tube is manufactured.

It is appreciated that various modifications to the present inventive concepts described herein may be apparent to those of ordinary skill in the art without departing from the scope of the present invention as defined by the herein appended claims.