Catheter and introducer catheter having torque transfer layer and method of manufacture
View Patent ↗The instant invention relates generally to catheters and to introducer catheters used to help deliver catheters or other medical devices to locations within the human body. In particular, the instant invention relates to large diameter catheters and introducer catheters having a torque transfer layer that includes at least two flat wires braided into a wire mesh. The flat wires have a width of at least about 0.007 inches and a depth of at least about 0.003 inches. The lumen diameter of the catheter is at least about 6 French. The torque transfer layer provides increased strength, flexibility, and kink resistance.
1. A catheter for cardiac surgery, comprising:
a tubular inner liner having a lumen diameter of at least about 6 French;
a torque transfer layer surrounding at least a portion of the inner liner, the torque transfer layer comprising at least two flat wires braided into a wire mesh, the flat wires being substantially rectangular in cross-section and having a width of at least about 0.007 inches and a depth of at least about 0.003 inches;
an outer sheath formed over to the torque transfer layer,
wherein the inner liner and the outer sheath define a catheter wall; and
a steering assembly comprising at least one pull wire that is captured within the catheter wall.
2. The catheter according to claim 1 , wherein the tubular inner liner is polymeric and the outer sheath comprises a melt-processing polymer.
3. The catheter according to claim 2 , wherein the melt-processing polymer occupies a plurality of voids of the wire mesh in the torque transfer layer.
4. The catheter according to claim 1 , wherein the lumen diameter is between about 7 French and about 32 French.
5. The catheter according to claim 1 , wherein the at least two flat wires have a ratio of width to thickness of at least about 2:1.
6. The catheter according to claim 5 , wherein the ratio of width to thickness is between about 2:1 and about 5:1.
7. The catheter according to claim 1 , wherein the flat wires are about 0.004″ thick by about 0.012″ wide.
8. The catheter according to claim 1 , wherein the flat wires are about 0.004″ thick by about 0.020″ wide.
9. The catheter according to claim 1 , wherein the flat wires comprise stainless steel.
10. The catheter according to claim 1 , wherein the torque transfer layer has a braid density between about 5 PPI and about 100 PPI.
11. The catheter according to claim 10 , wherein the torque transfer layer has a braid density between about 10 PPI and about 55 PPI.
12. The catheter according to claim 11 , wherein the torque transfer layer has a braid density between about 35 PPI and about 45 PPI.
13. The catheter according to claim 1 , wherein the torque transfer layer is braided in a one over, one-under pattern.
14. The catheter according to claim 1 , wherein the torque transfer layer comprises at least four flat wires braided in a two-over, two-under pattern.
15. The catheter according to claim 1 , further comprising an atraumatic tip bonded to a distal end of the catheter.
16. The catheter according to claim 1 , wherein the outer sheath varies in hardness along its length.
17. The catheter according to claim 16 , wherein the outer sheath comprises a plurality of segments having differing hardness characteristics, wherein the plurality of segments are reflow bonded together.
18. The catheter according to claim 1 , wherein the outer sheath includes a proximal segment and a distal segment, the proximal segment having a greater durometer than the distal segment.
19. The catheter according to claim 18 , wherein the distal segment comprises a tip segment and an intermediate segment positioned between the tip segment and the proximal segment, and wherein the intermediate segment has a durometer intermediate to the tip segment and the proximal segment.
20. The catheter according to claim 1 , wherein the torque transfer layer terminates proximally of the distal end of the catheter.
21. The catheter according to claim 1 , wherein the outer sheath is reflow bonded to the torque transfer layer.
22. The catheter according to claim 1 , wherein the steering assembly comprises at least one flat pull wire.
23. The catheter according to claim 22 , wherein the at least one flat pull wire is about 0.002″ thick by about 0.016″ wide.
24. The catheter according to claim 22 , wherein the at least one flat pull wire is about 0.004″ thick by about 0.012″ wide.
25. The catheter according to claim 22 , wherein the at least one flat pull wire is about 0.004″ thick by about 0.012″ wide.
26. The catheter according to claim 1 , wherein the steering assembly comprises two pull wires captured within the catheter wall and separated by about 180 degrees.