Devices and methods for crossing a chronic total occlusion
View Patent ↗A catheter comprises an elongate tubular member having a proximal end and a distal end, and a deflectable tip at the distal end of the elongate tubular member. The deflectable tip comprises a first helical coil having a first diameter and a second helical coil having a second diameter, the first diameter being larger than the second diameter. The first and second helical coils are arranged in the manner of a double helix. When viewed in cross-section, the first helical coil and the second helical coil are aligned at a first point on a circumference of each coil and misaligned at a second point on the circumference of each coil, where the second point is approximately 180 degrees from the first point. In certain embodiments the catheter further includes a dilatation balloon. Methods of use for crossing a chronic total occlusion are also described.
1. A catheter, comprising:
an elongate tubular member having a proximal region, a distal region, and a lumen extending therebetween;
a multilayer torque cable in the proximal region of the elongate tubular member, the multilayer torque cable having a first helical coil and a second helical coil, the first helical coil nested within the second helical coil and wound in a reverse direction from the second helical coil so that rotation of the first helical coil in a first direction causes the first helical coil to expand while rotation of the second helical coil in the first direction causes the second helical coil to compress and thereby interfere with the expansion of the first helical coil;
a monolayer helical coil in the distal region of the elongate tubular member, wherein the monolayer helical coil is an extension of the first helical coil; and
an outer jacket surrounding the monolayer helical coil to restrict expansion on rotation of the monolayer helical coil.
2. The catheter of claim 1 , wherein the multilayer torque cable further comprises a third helical coil surrounding the second helical coil.
3. The catheter of claim 1 , wherein the monolayer helical coil is annealed to prevent unwinding expansion on torquing the catheter.
4. The catheter of claim 1 , wherein the first helical coil is multifilar.
5. The catheter of claim 1 , wherein the second helical coil is multifilar.
6. The catheter of claim 1 , wherein the monolayer helical coil is multifilar.
7. The catheter of claim 1 , further comprising a balloon mounted on the distal region of the elongate tubular member, the balloon defining a chamber that communicates with an inflation lumen that extends to the proximal region of the elongate tubular member.
8. The catheter of claim 7 , wherein a second outer jacket is disposed about the multilayer torque cable, and wherein a proximal end of the balloon is bonded to the second outer jacket and a distal end of the balloon is bonded to the outer jacket surrounding the monolayer helical coil.