Adjustment for hydrocephalus shunt valve
An implantable medical device is disclosed that includes a valve seat and a valve member movable with respect to the valve seat. An adjustment circuit assembly includes a resistive element that is coupled to the valve member and operable to position the valve member relative to the valve seat so as to alter the pressure setting in response to a current applied to the resistive element. A reading circuit assembly includes an antenna coil, a sensing coil and a member moveable with respect to the sensing coil, the member configured to alter a resonant frequency of the reading circuit assembly as a function of a position of the member with respect to the sensing coil.
1. A device for controlling flow in a hydrocephalus shunt, comprising:
a valve seat;
a valve member interfacing with the valve seat to establish a pressure setting indicative of a pressure where fluid will flow through the valve seat;
an adjustment circuit assembly including a resistive element coupled to the valve member and operable to adjust force on the valve member relative to the valve seat so as to alter the pressure setting in response to a current applied to the resistive element; and
a reading circuit assembly including an antenna coil, a sensing coil and a member moveable with respect to the sensing coil, the member configured to alter a resonant frequency of the reading circuit assembly as a function of a position of the member with respect to the sensing coil.
2. The device of claim 1 wherein the adjustment circuit assembly further includes a setting coil electrically connected to the resistive element.
3. The device of claim 2 wherein the adjustment circuit assembly further includes a capacitor electrically connected to the setting coil and resistive element.
4. The device of claim 2 wherein the element is a shape memory alloy.
5. The device of claim 1 and further comprising a connector assembly coupling the adjustment circuit assembly with the valve member.
6. The device of claim 5 , wherein the connector assembly includes a spring, a cam follower, a cam, and a ratchet operably coupled to the adjustment circuit assembly.
7. The device of claim 6 wherein the cam has a variable radius about a rotational axis of the cam.
8. The device of claim 1 , wherein the reading circuit assembly further includes a capacitor electrically connected to the antenna coil and the sensing coil.
9. An implantable flow control device, comprising:
a valve having a plurality of pressure settings;
a connector assembly coupled to the valve and movable with respect to the valve to adjust a pressure setting for the valve;
an adjustment circuit assembly comprising:
a setting coil, and
a resistive element electrically connected to the setting coil, the resistive element coupled to the connector assembly;
a reading circuit assembly comprising:
an antenna coil,
a sensing coil electrically connected to the antenna coil,
a movable member coupled to the connector assembly and moveable with respect to the sensing coil; and
wherein inducement of current in the setting coil causes the resistive element to move the connector assembly relative to the valve and inducement of current in the antenna coil generates a signal indicative of the pressure setting.
10. The device of claim 9 , wherein the element is a shape memory alloy.
11. The device of claim 9 , wherein the connector assembly includes a spring, a cam follower, a cam, and a ratchet arm operably coupled to the adjustment circuit assembly.
12. The device of claim 11 , wherein the cam has a variable radius about a rotational axis of the cam.
13. The device of claim 9 , wherein the movable member is configured to alter a resonant frequency of the reading circuit assembly as a function of a position of the movable member with respect to the sensing coil.
14. The device of claim 9 , wherein the adjustment circuit assembly further includes an adjustment capacitor electrically connected to the setting coil and the resistive element.
15. The device of claim 9 , wherein the reading circuit assembly further includes a reading capacitor electrically connected to the antenna coil and the sensing coil.
16. A method of controlling flow of fluid in an implantable device, comprising:
providing a valve in the device adjustable to a plurality of pressure settings;
receiving an oscillating electromagnetic field resonant with an adjustment circuit assembly coupled with the valve;
inducing current in a resistive element of the adjustment circuit assembly;
adjusting a pressure setting of the device based on the current in the resistive element; and
providing a reading circuit assembly that includes an antenna coil, a sensing coil and a member moveable with respect to the sensing coil, the member configured to alter a resonant frequency of the reading circuit assembly as a function of a position of the member with respect to the sensing coil.
17. The method of claim 16 , wherein the element is a shape memory alloy.
18. The method of claim 16 , further comprising:
coupling a connector assembly including a spring, a cam follower, a cam, and a ratchet arm operably coupled to the adjustment circuit assembly.
19. The method of claim 18 , wherein the cam has a variable radius about a rotational axis of the cam.
20. The method of claim 18 , wherein inducing current in the resistive element causes the resistive element to heat and transition to a contracted state.
21. The method of claim 20 , further comprising:
removing current from the resistive element such that the resistive element cools and transitions to an expanded state.