Externally programmable valve assembly
An externally programmable shunt valve assembly that includes a magnetic rotor that is operable in response to an externally applied magnetic field and configured to increase or decrease the working pressure of the shunt valve assembly in finite increments.
1. A system comprising:
a magnetically programmable shunt valve assembly configured to control a fluid pressure and a flow rate of fluid between an inlet and an outlet, the valve assembly including
a housing, an exterior of the housing being formed of a physiologically compatible material,
an inlet port,
a valve seat,
a valve element seated in the valve seat, the valve element and the valve seat together forming an aperture through which the fluid flows, the fluid pressure and the flow rate of the fluid being controlled by a size of the aperture,
a cantilever spring configured to bias the valve element against the valve seat and thereby control the size of the aperture, the cantilever spring including a first spring arm and a second spring arm extending from a fixed point of attachment of the cantilever spring, the first spring arm having a free end that rests against the valve element,
a rotor casing,
a magnetically actuatable rotor disposed within the rotor casing, wherein rotation of the magnetically actuatable rotor relative to the rotor casing produces a selected pressure setting of the shunt valve assembly, and
a cam coupled to the magnetically actuatable rotor and positioned to engage the second spring arm such that the rotation of the magnetically actuatable rotor changes a tension of the first spring arm against the valve element, thereby controlling the size of the aperture and determining the selected pressure setting of the shunt valve assembly, wherein the first and second spring arms and the fixed point of attachment of the cantilever spring are together configured to provide a lever effect such that a first pressure applied by the cam to the second spring arm is translated by the cantilever spring into a second pressure applied against the valve element by the first spring arm, the second pressure being less than the first pressure;
an outlet port positioned between the rotor casing and the exterior of the housing, the shunt valve assembly configured such that the aperture opens when a pressure of the fluid in the inlet port exceeds the selected pressure setting of the shunt valve assembly so as to vent fluid through the aperture into the outlet port; and
a magnetic valve programmer configured to magnetically induce the rotation of the magnetically actuatable rotor relative to the rotor casing to set a pressure setting of the magnetically programmable shunt valve assembly to the selected pressure setting, wherein the aperture opens when a pressure of the fluid at the inlet exceeds the selected pressure setting of the shunt valve assembly so as to vent the fluid through the aperture to the outlet.
2. The system of claim 1 , wherein the programmer is configured to produce the pulses of the external magnetic field to induce the rotation of the magnetic rotor relative to the rotor casing so as to set the pressure setting of the shunt valve assembly to the selected pressure setting, and
wherein the programmer includes a rotor position detector in communication with a first Hall sensor and configured to determine a pressure setting of the shunt valve assembly based on the position of the magnetic rotor.
3. The system of claim 2 , wherein the valve assembly further includes a reference marker disposed in a fixed position on or in the housing, the reference marker configured to provide a magnetic reference of a known orientation.
4. The system of claim 3 , wherein the programmer further includes a second Hall sensor configured to measure a position of the reference marker.
5. The system of claim 4 , wherein the programmer further includes a reference detector in communication with the second Hall sensor and configured to determine the position of the magnetic rotor relative to the position of the reference marker.
6. The system of claim 1 , wherein the programmer is automated to adjust a number of the pulses of the magnetic field according to the selected pressure setting.
7. The system of claim 1 , further comprising an implantable gravity-activated valve coupled in series with the externally programmable implantable shunt valve assembly.
8. The system of claim 1 , wherein the programmer includes a plurality of magnetic coils arranged spaced apart from one another inside the programmer.
9. The system of claim 8 , wherein the programmer is coupled to each of the plurality of magnetic coils and configured to selectively activate one or more of the plurality of magnetic coils to produce the pulses of the external magnetic field.
10. The system of claim 1 , wherein the programmer includes a user interface configured to receive an input from the user that selects the selected pressure setting of the shunt valve assembly.
11. A method of treating hydrocephalus comprising:
implanting a shunt valve assembly of claim 1 having a ventricular catheter within a ventricular cavity of the patient's brain and distal catheter installed at a remote location in the patient's body where the fluid is to drain.
12. A method of determining a pressure setting of a valve assembly, the method comprising;
implanting the valve assembly of claim 1 in a patient in need thereof;
placing a Hall Sensor exterior to the patient and in proximity to the implanted shunt valve assembly,
wherein the Hall Sensor identifies an angle of rotation of the magnetic rotor and thereby determines the pressure setting of the shunt valve assembly.
13. A position control system comprising:
a magnetically programmable shunt valve assembly including
a housing,
a rotor casing disposed within the housing, the rotor casing including a plurality of casing teeth arranged around an inner surface of the rotor casing,
a magnetic rotor disposed within the housing and including a first and second rotor teeth that are configured to alternately engage the rotor casing teeth responsive to pulses of an external magnetic field, thereby causing rotation of the magnetic rotor relative to the rotor casing, each pulse of the external magnetic field producing a predetermined increment of rotation of the magnetic rotor relative to the rotor casing,
a valve element seated in a valve seat,
a cantilever spring including a cantilevered arm and a second arm extending parallel to one another from a fixed point of attachment of the cantilever spring, the cantilevered arm of the cantilever spring having a free end that rests against the valve element, and
a cam that engages the cantilever spring, the second arm of the cantilever spring resting against the cam with the cam being coupled to the magnetic rotor, such that rotation of the magnetic rotor causes rotation of the cam and adjusts a tension of the cantilever spring against the valve element;
a transmitter external to the housing of the magnetically programmable shunt valve assembly, the transmitter including at least one magnetic coil configured to produce the pulses of the external magnetic field to induce the rotation of the magnetic rotor relative to the rotor casing; and
a controller coupled to the transmitter and configured to control the transmitter to produce a selected number of the pulses of the external magnetic field so as to induce a selected amount of rotation of the magnetic rotor.
14. The position control system of claim 13 , wherein the controller further is configured to adjust a number of pulses of the magnetic field according to a selected pressure setting.
15. The position control system of claim 13 , wherein the controller further is configured to provide instructions to coil drive circuitry to drive the at least one magnetic coil.
16. The position control system of claim 15 , wherein the controller further is configured to receive inputs from at least one of a rotor position detector and a reference detector.
17. The position control system of claim 13 , wherein the controller is part of a programmer including a user interface.
18. The position control system of claim 17 , wherein the programmer further includes a communications interface configured to connect the programmer to another device.
19. The position control system of claim 13 , wherein the at least one magnetic coil includes a plurality of magnetic coils, and wherein the controller includes a plurality of ports that are respectively coupled to each of the plurality of magnetic coils, and
wherein the controller further is configured to be programmed to selectively activate one or more of the magnetic coils to actuate the magnetic rotor.
20. The position control system of claim 19 , wherein the controller further is configured to selectively activate one or more of the plurality of magnetic coils based on factors including at least one of an orientation of the magnetic rotor, a current pressure setting of the magnetically programmable shunt valve assembly.