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.
1. An adjustable shunt system, comprising:
an implantable flow control device, comprising:
a valve seat;
a valve member interfacing with the 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 movable 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; and
a tool, comprising:
an adjustment circuit operably couplable with the adjustment circuit assembly so as to generate an oscillating electromagnetic field so as to induce a current in the resistive element; and
a reading circuit operatively couplable with the reading circuit assembly and configured to induce a current in the antenna coil to generate a signal indicative of the pressure setting.
2. The system of claim h wherein the adjustment circuit assembly further includes a setting coil electrically connected to the resistive element.
3. The system of claim 2 , wherein the adjustment circuit assembly further includes a capacitor electrically connected to the setting coil and resistive element.
4. The system of claim 1 , wherein the reading circuit assembly further includes a capacitor electrically connected to the antenna coil and the sensing coil.
5. The system of claim 1 , wherein the adjustment circuit is configured to generate signals at a first frequency and the reading circuit is configured to generate signals at a second frequency different than the first frequency.
6. The system of claim 1 , wherein the reading circuit is configured to scan a signal across a range of frequencies in order to generate a signal in the antenna coil indicative of the pressure setting.
7. The system of claim 1 , wherein the adjustment circuit generates a signal having a frequency of approximately 100 kilohertz.
8. The system of claim 1 , wherein the reading circuit generates a signal having a frequency of approximately 1 megahertz.