Steerable catheter using flat pull wires and having torque transfer layer made of braided flat wires

Abstract

A catheter assembly includes an inner liner made of flexible material and an outer layer having a steering mechanism. The steering mechanism includes at least one flat wire and a corresponding lumen through which the flat wire may travel. The steering mechanism may also include at least one pull ring to which the flat wires are attached. A layer of heat shrink material may encompass the outer layer. A braided wire assembly may also be provided in the outer layer, and may be formed by braiding a plurality of flat wires into a wire mesh. The overall cross-section of the catheter assembly is preferably substantially circular. A catheter shaft may include a plurality of segments of differing hardness characteristics. The outer layer typically comprises a melt processing polymer such that the catheter assembly may be laminated using heat.

1 . A catheter assembly, comprising: 
 an inner liner made of flexible material; and    an outer layer having a steering mechanism, the steering mechanism comprising: 
 at least one flat wire; and  
 a corresponding lumen for each of the at least one flat wire through which the flat wire may travel;  
   wherein the outer layer comprises a braided wire assembly that includes at least two flat wires braided into a wire mesh.    
     
     
         2 . The catheter assembly of  claim 1 , further comprising a layer of heat shrink material encompassing the outer layer, wherein the inner liner includes a central lumen, and wherein the catheter assembly has a cross section with an outer shape that is substantially circular.  
     
     
         3 . The catheter assembly of  claim 2 , further comprising at least one pull ring to which the at least one flat wire is secured, whereby the catheter assembly may be steered by controlling the at least one flat wire.  
     
     
         4 . The catheter assembly of  claim 3 , wherein the outer layer comprises a melt processing polymer, wherein the steering mechanism comprises a pull ring to which the at least one flat wire is secured, and wherein the pull ring comprises at least two flow holes, said outer layer being bonded to the pull ring such that the melt processing polymer occupies the at least two flow holes.  
     
     
         5 . The catheter assembly of  claim 3 , wherein the steering mechanism comprises at least two flat wires and at least two corresponding preformed tubes through which the at least two flat wires may travel, wherein the at least two flat wires are secured to the at least one pull ring, and wherein the at least two preformed tubes have cross-sections that are different in shape from a cross-section of the corresponding flat pull wires.  
     
     
         6 . The catheter assembly of  claim 5 , wherein the steering mechanism comprises a single pull ring to which the at least two flat wires are secured.  
     
     
         7 . The catheter assembly of  claim 6 , wherein the single pull ring comprises a right circular cylinder having a slot for each of the at least two flat wires.  
     
     
         8 . The catheter assembly of  claim 7 , wherein the outer layer comprises a melt processing polymer, wherein the steering mechanism comprises a pull ring to which the at least two flat wires are secured, and wherein the pull ring comprises at least two flow holes, said outer layer being bonded to the pull ring such that the melt processing polymer occupies the at least two flow holes.  
     
     
         9 . The catheter assembly of  claim 2 , wherein the steering mechanism comprises at least two flat wires and at least two corresponding lumens through which the at least two flat wires may travel.  
     
     
         10 . The catheter assembly of  claim 9 , wherein each of the at least two flat wires has a cross-section that is rectangular, and wherein each of the at least two lumens has a cross-section selected from the group consisting of oval, round, and elliptical.  
     
     
         11 . The catheter assembly of  claim 9 , wherein each of the at least two flat wires has a cross-section that is measured X in one direction and at least 3X in a second direction, said second direction being substantially orthogonal to the first direction.  
     
     
         12 . The catheter assembly of  claim 9 , wherein each of the at least two flat wires is manufactured with a smooth surface to reduce friction between the flat wire and the corresponding lumen.  
     
     
         13 . The catheter assembly of  claim 1 , wherein the inner liner is polymeric and has a lumen diameter of at least about 6 French, and wherein the flat wires in the braided wire assembly are substantially rectangular in cross-section and have a width of at least about 0.007 inches and a depth of at least about 0.004 inches.  
     
     
         14 . The catheter assembly of  claim 13 , wherein the outer layer comprises a melt processing polymer, and wherein the melt-processing polymer occupies a plurality of voids of the wire mesh in the braided wire assembly.  
     
     
         15 . The catheter assembly of  claim 13 , wherein the inner liner has a lumen diameter of between about 7 French and about 32 French.  
     
     
         16 . The catheter assembly of  claim 13 , wherein the at least two flat wires have a ratio of width to thickness of at least about 2:1.  
     
     
         17 . The catheter assembly of  claim 13 , wherein the braided wire assembly has a braid density between about 5 PPI and about 100 PPI.  
     
     
         18 . The catheter assembly of  claim 1 , wherein the braided wire assembly is braided in a one-over, one-under pattern.  
     
     
         19 . The catheter assembly of  claim 1 , wherein the braided wire assembly comprises at least four flat wires braided in a two-over, two-under pattern.  
     
     
         20 . A method of manufacturing a catheter, comprising the steps of: 
 providing a mandrel;    placing a lining material over the mandrel to form an inner liner;    providing at least one flat shaped wire;    placing a flexible liner over each of the at least one flat shaped wires to create at least one flat lumen;    placing a braided wire assembly over the inner liner and the at least one flat lumen, the braided wire assembly including at least two flat wires braided into a wire mesh;    covering the braided wire assembly with a melt processing polymer;    applying sufficient heat to the melt processing polymer to raise the temperature of the polymer above its melting point;    cooling the assembly; and    removing the mandrel, thereby forming a catheter.    
     
     
         21 . The method of  claim 20 , further comprising: 
 covering the melt processing polymer with shrink wrap tubing; and    removing the shrink wrap tubing after the melting process.    
     
     
         22 . The method of  claim 20 , further comprising: 
 covering the braided wire assembly with one or more flexible layers; and    covering the melt processing polymer with shrink wrap tubing.    
     
     
         23 . The method of  claim 20 , wherein the step of providing at least one flat shaped wire comprises providing at least one flat wire having a cross-section that is rectangular, and wherein the step of placing a flexible liner over each of the at least one flat shaped wires comprises placing a preformed flexible tube over each of the at least one flat shaped wires, wherein the preformed flexible tube has a cross-section selected from the group consisting of oval, round, and elliptical.  
     
     
         24 . The method of  claim 20 , wherein the inner liner is polymeric and has a lumen diameter of at least about 6 French, and wherein the flat wires in the braided wire assembly are substantially rectangular in cross-section and have a width of at least about 0.007 inches and a depth of at least about 0.004 inches.  
     
     
         25 . The method of  claim 20 , wherein the flat wires of the braided wire assembly are braided at a braid density of about 5 PPI to about 100 PPI.