Endoscopic tissue resection device
An endoscopic tissue resection device configured to be attached at a distal tip of an endoscope is disclosed. The device comprises a cap, a snare sheath, a snare, and a spring wire. The snare comprises a collapsible snare wire configured to be retracted from the cavity of the cap into the snare sheath, the collapsible snare wire reversibly collapsing upon retraction, and to be advanced from the snare sheath into the cavity of the cap, the collapsible snare wire reversibly expanding upon advancement. The spring wire is reversibly deflectable from a resting state to a deflected state. In the resting state the spring wire orients and stabilizes an apex of the collapsible snare wire within the cap such that two opposing wire portions of the collapsible snare wire are positioned in apposition to a distal opening of the cap.
1. An endoscopic tissue resection device configured to be attached at a distal tip of an endoscope, the device comprising a cap, a snare sheath, a snare, and a spring wire, wherein:
the cap comprises a cap body, a proximal end, a proximal opening, a distal end, and a distal opening;
the cap body defines a cavity for retraction of a tissue and has an inner perimeter;
the snare sheath comprises a proximal end, a distal end, and a snare sheath body therebetween;
the distal end of the snare sheath is affixed to the cap body along the inner perimeter of the cap body;
the snare comprises a snare actuation cable and a collapsible snare wire;
the snare actuation cable comprises a proximal end, a distal end and a snare actuation cable body therebetween, is disposed within the snare sheath, and is configured to be translated proximally and distally within the snare sheath;
the collapsible snare wire comprises a base, an apex opposite the base, and two opposing wire portions extending therebetween, is disposed within the cavity of the cap, and is reversibly collapsible from an expanded state to a collapsed state;
the base of the collapsible snare wire is attached to the snare actuation cable at or near the distal end of the snare actuation cable;
the collapsible snare wire is configured to be retracted from the cavity of the cap into the snare sheath by translating the snare actuation cable proximally within the snare sheath, the collapsible snare wire reversibly collapsing from the expanded state to the collapsed state upon retraction, and to be advanced from the snare sheath into the cavity of the cap by translating the snare actuation cable distally within the snare sheath, the collapsible snare wire reversibly expanding to the expanded state upon advancement;
the spring wire is disposed within the cavity of the cap and comprises a proximal end, a distal end, and a flexible portion therebetween;
the proximal end of the spring wire is attached to the cap body at or near the proximal end of the cap;
the distal end of the spring wire is attached to the apex of the collapsible snare wire;
the spring wire is reversibly deflectable from a resting state to a deflected state, the spring wire being in the resting state when the collapsible snare wire is disposed within the cavity of the cap and deflecting to the deflected state when the collapsible snare wire is retracted into the snare sheath;
in the resting state the spring wire orients and stabilizes the apex of the collapsible snare wire within the cap, at or near the distal opening of the cap, opposite the distal end of the snare sheath, such that the two opposing wire portions of the collapsible snare wire are positioned in apposition to the distal opening of the cap;
during deflection the spring wire bends along an arced path to the snare sheath; and
the distal end of the snare sheath is recessed into the cavity of the cap relative to the distal end of the spring wire to allow the spring wire to bend along the arced path.
2. The endoscopic tissue resection device according to claim 1 , wherein the cap has an outer diameter of 0.5 to 1.5 cm.
3. The endoscopic tissue resection device according to claim 1 , wherein the cavity of the cap has an inner depth of 0.5 cm to 1.5 cm.
4. The endoscopic tissue resection device according to claim 1 , wherein the cavity of the cap has an inner diameter, the spring wire has a length, and the inner diameter of the cavity of the cap is greater than the length of the spring wire.
5. The endoscopic tissue resection device according to claim 1 , wherein the distal end of the cap has an oblique profile.
6. The endoscopic tissue resection device according to claim 1 , wherein the distal end of the cap comprises a lip within the cavity of the cap for retaining the collapsible snare wire within the cavity of the cap.
7. The endoscopic tissue resection device according to claim 1 , wherein the two opposing wire portions of the collapsible snare wire have an approximately hexagonal, circular, or elliptical shape in the expanded state.
8. The endoscopic tissue resection device according to claim 1 , wherein the distal opening of the cap has an inner circumference having a diameter, and the collapsible snare wire in the expanded state apposes the inner circumference of the distal opening of the cap closely enough that any gaps between the two opposing wire portions of the collapsible snare wire and the inner circumference of the distal opening of the cap are not more than 10%, 8%, 6%, 4%, or 2% of the diameter of the inner circumference of the distal opening of the cap.
9. The endoscopic tissue resection device according to claim 1 , wherein the distal opening of the cap has an inner circumference, and the collapsible snare wire in the expanded state apposes the inner circumference of the distal opening of the cap closely enough that any gaps between the two opposing wire portions of the collapsible snare wire and the inner circumference of the distal opening of the cap are not more than 5 mm, 4 mm, 3 mm, 2 mm, or 1 mm.
10. The endoscopic tissue resection device according to claim 1 , wherein the distal end of the cap has a distal edge, the cavity of the cap has an inner depth, and the collapsible snare wire in the expanded state rests sufficiently flush to the distal edge of the distal end of the cap that any gaps between the two opposing wire portions of the collapsible snare wire and the distal edge of the distal end of the cap are not more than 20%, 16%, 12%, 8%, or 4% of the inner depth of the cavity of the cap.
11. The endoscopic tissue resection device according to claim 1 , wherein the distal end of the cap has a distal edge, the cap has an axis extending from the proximal end of the cap to the distal end of the cap, and the collapsible snare wire in the expanded state rests sufficiently flush to the distal edge of the distal end of the cap that any gaps between the two opposing wire portions of the collapsible snare wire and the distal edge of the distal end of the cap are not more than 5 mm, 4 mm, 3 mm, 2 mm, or 1 mm as measured along the axis.
12. The endoscopic tissue resection device according to claim 1 , wherein the snare sheath has an axis extending from its proximal end to its distal end, and the collapsible snare wire is shaped to deflect from the axis during advancement of the collapsible snare wire from the distal end of the snare sheath.
13. The endoscopic tissue resection device according to claim 1 , wherein the device further comprises a blade disposed in the cavity of the cap adjacent the distal end of the snare sheath.