Biopsy device with variable speed cutter advance
View Patent ↗A biopsy device having a translating and rotating cutter is disclosed. The translational speed of the cutter is varied using a variable pitch member. The variable pitch member can include a shaft having a relatively coarse threaded portion for rapid cutter advance and a relatively finer threaded portion for cutter advance during tissue severing.
1. A biopsy device comprising:
(a) a probe assembly comprising:
(i) a cannula having a closed distal end and a lateral tissue receiving opening spaced proximally from the closed distal end, and
(ii) a hollow cutter operable to sever tissue received in the tissue receiving opening;
(b) a holster configured to releasably receive the probe assembly, the holster comprising:
(i) a first motor operable to impart rotational motion to the cutter, and
(ii) a second motor operable to impart translational motion to the cutter;
(c) a reprogrammable non-transitory memory operatively associated with the first and second motors, the reprogrammable non-transitory memory including a current profile for each of the first and second motors; and
(d) a rotating member operatively associated with at least one motor of the first and second motors, wherein the rotating member has a threaded portion with varying thread pitch.
2. The biopsy device of claim 1 , wherein the reprogrammable memory comprises a current profile for advancing and retracting the cutter.
3. The biopsy device of claim 1 , wherein the reprogrammable memory comprises a current profile for advancing the cutter and a current profile for retracting the cutter, wherein the current profile for advancing the cutter is different from the current profile for retracting the cutter.
4. The biopsy device of claim 1 , wherein the first and second motors are DC motors.
5. The biopsy device of claim 1 , further comprising a planetary gear operatively associated with at least one motor of the first and second motors.
6. The biopsy device of claim 1 , wherein the diameter of the threaded portion varies along the length of the threaded portion.
7. A method of operating a biopsy device having an outer cannula with a side tissue receiving port, a cutter for severing tissue received in the side tissue port, and at least one motor for providing motion of the cutter, the method comprising the steps of:
(a) advancing and rotating the cutter to sever tissue;
(b) determining if a predetermined period of time has elapsed once the cutter reaches a predetermined longitudinal position; and
(c) stopping the at least one motor if the predetermined period of time has elapsed.
8. The method of claim 7 , further comprising the step of determining the current of the at least one motor if the predetermined period of time has not elapsed.
9. The method of claim 7 , further comprising:
(a) measuring the current of the at least one motor; and
(b) comparing the measured current to a predetermined current profile.
10. The method of claim 9 , further comprising adjusting current to the motor if the difference between the measured current and the current profile is greater than a predetermined amount.
11. The method of claim 10 , wherein the act of adjusting is operative to change a rate at which the cutter translates relative to the outer cannula.
12. The method of claim 9 , wherein the current profile provides a maximum current for translating the cutter.
13. A method of operating a biopsy device having an outer cannula with a side tissue receiving port, a cutter for severing tissue received in the side tissue port, a translation motor for providing translation of the cutter, and a rotation motor for providing rotation of the cutter, the method comprising the steps of:
(a) advancing and rotating the cutter to sever tissue;
(b) stopping the translation motor; and
(c) continuing to operate the rotation motor if a predetermined period of time has not elapsed upon the cutter reaching a predetermined longitudinal position.