Medical guidewire

Abstract

Provided is a guidewire including a core shaft, an outer flexible tube, and an inner flexible tube that surrounds a distal end portion of the core shaft. The inner flexible tube is disposed in the outer flexible tube so that a distal end thereof is positioned between the distal end of the core shaft and a proximal end of the core shaft so as to be separated from the core shaft. A first joint is formed so as to join the distal end of the inner flexible tube to the core shaft. At least one second joint is formed so as to join the outer flexible tube to the inner flexible tube. The at least one second joint is positioned between the first joint and the proximal end of the core shaft.

What is claimed is: 
     
       1. A medical guidewire comprising:
 a core shaft including a distal end portion having a small diameter; 
 an outer flexible tube that surrounds an outer surface of the core shaft; and 
 an inner flexible tube disposed in completely within the outer flexible tube, the inner flexible tube surrounding the distal end portion of the core shaft, wherein  
 wherein a distal end of the core shaft is joined to a distal end of the outer flexible tube, 
 wherein the inner flexible tube is disposed so that a distal end thereof is positioned between the distal end of the core shaft and a proximal end of the core shaft so as to be separated from the distal end of the core shaft, and 
 wherein a first joint is formed so as to join the distal end of the inner flexible tube to the core shaft without jointing the outer flexible tube so as to be separated from the outer flexible tube, and at least one second joint is formed so as to join the outer flexible tube to the inner flexible tube without jointing the core shaft, the at least one second joint being positioned between the first joint and the proximal end of the inner flexible tube, and 
 the inner flexible tube has a tapered shape in which an outside diameter of the inner flexible tube gradually decreases toward a distal end thereof. 
 
     
     
       2. The medical guidewire according to  claim 1 , further comprising:
 a stranded wire disposed in the inner flexible tube, the stranded wire extending from the distal end of the inner flexible tube parallel to the distal end portion of the core shaft. 
 
     
     
       3. The medical guidewire according to  claim 1 ,
 wherein an entire inner flexible tube is disposed in the outer flexible tube, and the inner flexible tube has a tapered shape in which an outside diameter gradually decreases toward a distal end thereof.   
     
     
       4. The medical guidewire according to  claim 1 ,
 wherein an entire inner flexible tube is disposed in the outer flexible tube, and an outside diameter of the inner flexible tube decreases stepwise toward a distal end thereof. 
 
     
     
       5. The medical guidewire according to  claim 1 ,
 wherein the inner flexible tube is a hollow stranded-wire coil in which a plurality of metal strands are stranded. 
 
     
     
       6. The medical guidewire according to  claim 1 ,
 wherein the outer flexible tube is a single-wire coil including a large-pitch portion extending from the distal end of the outer flexible tube toward the proximal end of the outer flexible tube by a predetermined distance, the large-pitch portion having a pitch that is larger than a pitch of a proximal end portion of the outer flexible tube, and 
 wherein a proximal end of the large-pitch portion is positioned between the first joint and the at least one second joint. 
 
     
     
       7. A medical guidewire comprising:
 a core shaft including a distal end portion having a small diameter; 
 an outer flexible tube that surrounds an outer surface of the core shaft; and 
 an inner flexible tube disposed in completely within the outer flexible tube, the inner flexible tube surrounding the distal end portion of the core shaft, wherein  
 wherein a distal end of the core shaft is joined to a distal end of the outer flexible tube, 
 wherein the inner flexible tube is disposed so that a distal end thereof is positioned between the distal end of the core shaft and a proximal end of the core shaft so as to be separated from the distal end of the core shaft, and 
 wherein a first joint is formed so as to join the distal end of the inner flexible tube to the core shaft without jointing the outer flexible tube, at least one second joint is formed so as to join the outer flexible tube to the inner flexible tube without jointing the core shaft, and a third joint is formed so as to join the proximal end of the inner flexible tube to the core shaft without jointing the outer flexible tube, the at least one second joint being positioned between the first joint and the third joint, and 
 the inner flexible tube has a tapered shape in which an outside diameter of the inner flexible tube gradually decreases toward a distal end thereof. 
 
     
     
       8. The medical guidewire according to  claim 7 ,
 wherein the third joint is positioned between the at least one second joint and the proximal end of the core shaft. 
 
     
     
       9. The medical guidewire according to  claim 7 , further comprising:
 a stranded wire disposed in the inner flexible tube, the stranded wire extending from the distal end of the inner flexible tube parallel to the distal end portion of the core shaft. 
 
     
     
       10. The medical guidewire according to  claim 7 ,
 wherein an entire inner flexible tube is disposed in the outer flexible tube, and the inner flexible tube has a tapered shape in which an outside diameter gradually decreases toward a distal end thereof.   
     
     
       11. The medical guidewire according to  claim 7 ,
 wherein an entire inner flexible tube is disposed in the outer flexible tube, and an outside diameter of the inner flexible tube decreases stepwise toward a distal end thereof. 
 
     
     
       12. The medical guidewire according to  claim 7 ,
 wherein the inner flexible tube is a hollow stranded-wire coil in which a plurality of metal strands are stranded. 
 
     
     
       13. The medical guidewire according to  claim 7 ,
 wherein the outer flexible tube is a single-wire coil including a large-pitch portion extending from the distal end of the outer flexible tube toward the proximal end of the outer flexible tube by a predetermined distance, the large-pitch portion having a pitch that is larger than a pitch of a proximal end portion of the outer flexible tube, and 
 wherein a proximal end of the large-pitch portion is positioned between the first joint and the third joint. 
 
     
     
       14. The medical guidewire according to  claim 7 ,
 wherein the third joint is positioned between the at least one second joint and the proximal end of the inner flexible tube. 
 
     
     
       15. The medical guidewire according to claim 1, wherein at least a portion of the distal end of the core shaft is made of a pseudoelastic alloy, and at least a portion of the proximal end of the core shaft is made of a stainless steel alloy.