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Abstract

An apparatus and method of providing radiopaque marking for a coil spring. The coil spring will typically be used for medical applications within the cardiovascular system or other region wherein the assistance of a spring guide wire is necessary or desirable. Likely applications may include guide wires, angioplasty catheters, or infusion catheters. The basic spring guide wire is formed of a multifilar (e.g. quadrifilar) structure. At least one of the wires within the quadrifilar structure is drawn from a highly radiopaque material, such as platinum or a platinum alloy. The remaining wires are of a convenient base material such as stainless steel. The resulting quadrifilar structure will provide a degree of radiopacity over its length with one of four strands being highly visible under fluoroscopic energy. Various points along the spring guide wire may be further distinctively marked by changing the number of strands within the multifilar structure. One platinum wire within a trifilar structure is more visible fluoroscopically than in a quadrifilar structure. Similarly, the single platinum wire becomes correspondingly even more visible in bifilar and unifilar structures. These transitions are easily implemented in the coil winding process through the simple termination of one or more of the wires of the base material with a corresponding change in winding pitch of the remaining wire(s). The result is a marking of various points along the spring guide wire without the addition of any stiffness or change in handling characteristics.

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First Claim