Intravascular devices, systems, and methods to address eye disorders
A method may include accessing an artery in communication with an ophthalmic artery of a subject, and advancing a microcatheter along the accessed artery so as to align a distal end of the microcatheter with an ostium of the ophthalmic artery, wherein the microcatheter includes a lumen having a guidewire positioned therein. In addition, the method includes proximally withdrawing the guidewire relative to the microcatheter so as to enable a distal portion of the microcatheter to assume a curved relaxed configuration, and cannulating the ostium with the distal portion of the microcatheter when the distal portion is in the curved relaxed configuration.
1. A microcatheter, comprising:
a shaft having variable flexibility along a length thereof, the shaft including:
a multilayered proximal section including a proximal section outer layer;
a multilayered mid-section including a mid-section outer layer that is more flexible than the proximal section outer layer;
a multilayered distal section including a distal section outer layer that is more flexible than the mid-section outer layer, and a braid; and
a distal tip including a variable pitch coil, the variable pitch coil having a distal closed-gap pitch, a proximal open-gap pitch, and a middle open-gap pitch greater than the proximal pitch, a distal end of the variable pitch coil terminating proximally of a distalmost end of the distal tip,
wherein the braid of the distal section terminates at a distal end of the distal section and abuts a proximal end of the variable pitch coil.
2. The microcatheter of claim 1 , wherein an outer diameter of the distal tip is tapered toward the distal end of the distal tip.
3. The microcatheter of claim 1 , wherein the multilayered distal section includes a dual-layer coil of helical hollow strands, wherein the helical hollow strands have an elliptical cross-sectional shape.
4. The microcatheter of claim 1 , wherein the proximal section outer layer includes a polymer, and wherein the multilayered proximal section further includes a dual-layer coil comprising a helical hollow strand of wire, a single-layer braid, and an inner liner.
5. The microcatheter of claim 4 , wherein the mid-section outer layer includes a polymer that is more flexible than the polymer of the proximal section outer layer, and wherein the multilayered mid-section further includes the dual-layer coil comprising the helical hollow strands of wire, the single-layer braid, and the inner liner.
6. The microcatheter of claim 5 , wherein the distal section outer layer includes a polymer that is more flexible than the polymer of the mid-section outer layer, and wherein the multilayered distal section further includes the dual-layer coil comprising the helical hollow strands of wire, the single-layer braid, and the inner liner.
7. The microcatheter of claim 6 , wherein the distal tip further includes a distal tip outer layer.
8. The microcatheter of claim 7 , wherein a wall thickness of the distal tip outer layer is greater than a wall thickness of the distal section outer layer.
9. A microcatheter, comprising:
a shaft having variable flexibility along a length thereof, the shaft including:
a multilayered proximal section;
a multilayered mid-section that is more flexible than the multilayered proximal section;
a multilayered distal section that is more flexible than the multilayered mid-section, the multilayered distal section including:
a distal section outer layer;
a dual-layer coil having an inner coil layer and an outer layer coil;
a single-layer braid; and
an inner liner; and
a distal tip including:
a distal tip outer layer;
a single-layer coil having a distal closed-gap pitch, a proximal open-gap pitch, and a middle open-gap pitch greater than the proximal pitch, wherein the single-layer coil terminates proximally of a distalmost end of the distal tip; and
the inner liner,
wherein a distal-most end of the single-layer braid abuts the proximal end of the single-layer coil at an abutment,
wherein the outer layer coil of the dual-layer coil extends over the abutment between the single-layer braid and the proximal end of the single-layer coil, and the inner layer coil of the dual-layer coil terminates at the abutment between the single-layer braid and the proximal end of the single-layer coil, and
wherein, in a first configuration, a central longitudinal axis of the distal tip extends along a straight line, while, in a second configuration, the central longitudinal axis of the distal tip is curved.
10. The microcatheter of claim 9 , wherein an outer diameter of the distal tip is tapered toward the distal end of the distal tip.
11. The microcatheter of claim 9 , wherein the dual-layer coil is formed of helical hollow strands of wire, wherein the helical hollow strands of wire have an elliptical cross-sectional shape.
12. The microcatheter of claim 9 , wherein the multilayered proximal section includes an outer layer formed of a polymer, the dual-layer coil comprising the helical hollow strands of wire, the single-layer braid, and the inner liner.
13. The microcatheter of claim 12 , wherein the multilayered mid-section includes an outer layer that includes a polymer that is more flexible than the polymer of the outer layer of the proximal section, and wherein the multilayered mid-section further includes the dual-layer coil comprising the helical hollow strands of wire, the single-layer braid, and the inner liner.
14. The microcatheter of claim 13 , wherein the distal section outer layer includes a polymer that is more flexible than the polymer of the mid-section outer layer.
15. The microcatheter of claim 14 , wherein the distal tip outer layer includes a polymer having a wall thickness that is greater than a wall thickness of the polymer of the distal section outer layer.
16. A microcatheter, comprising:
a shaft having variable flexibility along a length thereof, the shaft including:
a proximal section including a solid core push wire and an outer layer;
a plurality of distal sections including:
a first multilayered distal section having a guidewire port at a proximal end;
a second multilayered distal section extending from the first multilayered distal section, the second distal multilayered section being more flexible than the first multilayered distal section;
a third multilayered distal section extending from the second multilayered distal section, the third multilayered distal section being more flexible than the second multilayered distal section; and
a fourth multilayered distal section extending from the third multilayered distal section, the fourth multilayered distal section being more flexible than the third multilayered distal section; and
a distal tip including a variable pitch coil having a distal closed-gap pitch, a proximal open-gap pitch, and a middle open-gap pitch greater than the proximal pitch.
17. The microcatheter of claim 16 , wherein the outer layer of the proximal section is formed of a polyolefin heat shrink tubing.
18. The microcatheter of claim 16 , wherein a diameter of the push wire of the proximal section tapers distally from 0.023″ to 0.010″.
19. The microcatheter of claim 16 , wherein the distal tip section includes a shape profile, wherein the shape profile includes any one of a straight line, a line with a 45° bend, a line with a 90° bend, a line with a 180° bend, a shepherd's hook, or an abbreviated shepherd's hook.
20. The microcatheter of claim 16 , wherein the distal tip section is formed into a shape of a shepherd's hook having a first curve in a first direction, and a second curve in a second direction that is different from the first direction, wherein the second curve extends from a distal end of the first curve.