Extendable guidewire

#This invention pertains generally to cardiovascular procedures such as angioplsaty, angiography and valvuloplasaty, and more particularly to an extendable guidewire and the methods of manufacturing and using the same.

#Guide wires are currently used to facilitate the placement of dilatation catheters in the arterial system of a patent for cardiovascular procedures such as angioplasty, angiography and valvuloplasty. The guidewire is typically on the order of 20-50 cm longer thana the catheter to permit the guidewire and the catheter to be advanced relative to each other as they are steered into position within the patient's body. Suitable guidewires are described in U.S. Pat. No. 4,538,622 (Samson et al.) and U.S. Pat. No. 4,569,347 (Frisbie) which are hereby incorporated herein in their entirety.

#In the usual procedure to change dilatation catheters, the guidewire is removed from the patient, and an exchange wire is inserted in its place. The exchange wire is substantially longer than the guidewire, and it generally extends outside the patient's body for a distance greater than the length of the catheter. With a dilation catheter having a length on the order of 120-140 cm, for example, a guidewire might have a length on the order of 175 cm, and an exchange wire might have a length on the order of 300 cm. The use of an exchange wire has the obvious disadvantage that it adds extra steps to the angioplasty procedures. In addition, it requires the doctor to have an additional wire for this purpose.

#FIG. 1 is a fragmentary centerline sectional view of an embodiment of an extendable guidewire according to the invention.

#FIG. 2 is a cross-sectional view taken along line 2--2 in FIG. 1.

#As illustrated in the drawings, the guidewire has a main section 11 which is adapted to be inserted into the patient's vascular system and an auxiliary section 12 which can be connected and disconnected to the proximal end of the main section. Section 11 has an elongated shaft 13 with a flexible tip (not shown) at its distal end and a tapered portion 14 at its proximal end. Details of of this structure can be found in the references cited previously and incorporate herein by reference thereto. Section 12 also has an elongated shaft 1 with a connector 17 at its distal end for mating engagement with the tapered portion at the proximal end of Section 11. The guidewire is intended for use in positioning a dilatation catheter (not shown) in the cardiovascular system of a patient, and section 11 has a length corresponding to the length of a conventional guidewire for this purpose. Details of typical dilatation catheters can be found in the references cited previously and incorporated herein.

#Section 12 has a length such that when the two sections are connected together the wire has an overall length suitable for exchanging catheters without removing section 11 from the patient's body. With a dilatation catheter having a length on the order of 120-140 cm, for example, section 11 might have a length on the order of 140-175 cm, and section 12 might have a length on the order of 125-160 cm.

#Shafts 13, 16 can be fabricated from any suitable material such as stainless steel, and neach should have a diameter such that a dilatation catheter can pass freely over them. Although two shafts 13 and 16 do not have to have exactly the same diameter, it is preferably that the two shafts be of substantially the same diameter in order to provide a smooth transition between them. In one presently preferred embodiment for use in coronary angioplasaty, shaft 13 has a diameter on the order of 0.013-0.016 inch, and shaft 16 has a diameter of 0.014 inch. Either or both of the shafts can be provided with a coating of Teflon or another suitable low friction material to facilitate movement of the catheter over the wire.