Patent Description:
Generally, a fluid flow control device includes a one-way control valve for controlling the flow of cerebrospinal (CSF) fluid out of a brain ventricle and preventing backflow of fluid into the brain ventricle. One example of a fluid flow control device is disclosed, for example, in <CIT> entitled, "Implantable Adjustable Fluid Flow Control Valve". Hydrocephalus, a neurological condition which may affect infants, children and adults, results from an undesirable accumulation of fluids, such as CSF, within the ventricles, or cavities, of the brain and which accumulation may exert extreme pressure in the brain and, in infants, skull deforming forces. Treatment of hydrocephalus often involves draining CSF away from the brain ventricles utilizing a drainage or shunt system including one or more catheters and a shunt valve which may generally be described as a fluid flow control device. The shunt valve, or fluid flow control device, may have a variety of configurations and may be adjustable in that the valve mechanism of the device may be set to a threshold pressure level at which fluid may be allowed to begin to flow through the valve and drain away from the brain. Fluid flow control devices may be subcutaneously implantable and percutaneously adjustable. Flow control devices may have a number of pressure settings and may be adjustable to the various pressure settings via external magnetic adjustment tools. Some fluid flow control devices are magnetic in that the devices include a magnetic rotor or rotor assembly which interacts with a valve mechanism and an adjustment mechanism to selectively adjust a valve opening pressure. The magnetic rotor or rotor assembly may magnetically couple with an external magnetic adjustment tool or tools. Magnetized rotors often include a single magnet or dual magnets arranged or configured to have aligned horizontal polarity. The magnetic adjustment tools are designed to externally (i.e., external to a patient) couple to a rotor magnet of a fluid flow control device implanted in a patient such that upon coupling, the rotor may be deliberately rotated to thereby adjust the pressure setting of the device non-invasively. Adjustment tools can include magnets which may be placed in line with the rotor magnet or magnets in order to couple to and drive the rotor externally, or through the tissue, after the valve is implanted. Typically, an adjustment tool is placed externally, for example, on the patient's head and in proximity to the implanted device. In this manner, it is possible to set the valve rotor into a desired position in a non-invasive manner.

A rotor or rotor assembly having a single magnet or dual magnets with aligned horizontal polarity may cause the magnetic rotor to be susceptible to movement or inadvertent setting adjustment by a strong nearby magnetic field since the internal magnetic elements arranged in this manner may tend to align with the external field. A magnetic rotor might thus be unintentionally adjusted when in the presence of a strong external magnetic field such as encountered in a magnetic resonance imaging (MRI) procedure, for example an MRI field of up to <NUM> Tesla. Unintentional adjustment can result in the rotor moving to a position whereby the pressure setting of the fluid flow control device is other than optimal for the particular patient. Depending upon how a valve or device (and thereby the magnetic rotor) enters the MRI, the magnetic field of the MRI equipment may work to turn (i.e., rotate) the rotor to a new setting, or, if the valve enters the MRI equipment at a <NUM> degree angle to the MRI magnetic field, the MRI field may work to flip (tilt) the rotor. Potential unintended adjustment may therefore require checking and/or re-adjustment via the external accessories and/or adjustment tools each time a patient is or has been in the presence of a strong external magnetic field. Therefore, the need exists for a fluid flow control device, rotor, and/or magnet which provides increased resistance to inadvertent setting changes.

Intentional adjustment, verification and indication of fluid flow control device or valve pressure settings may be accomplished via external tools and/or accessories including, for example, locator, indicator and/or adjustment tools. As described above, an adjustment tool may include a magnet or magnets for coupling to and rotating an implanted rotor assembly thereby setting a device or valve pressure threshold. However, since during use the adjustment tool is located at a distance from the implanted valve and is external to the patient, device components and/or tissue between the adjustment tool magnets and valve magnet or magnets may interfere with the magnetic coupling of the two. This interference can result in a decreased magnetic field strength making intentional adjustment of pressure settings more challenging. Therefore it may be desirable to improve or increase the magnetic coupling or magnetic field strength between an implanted fluid flow control device and related external magnetically coupleable accessories.

<CIT>describes a subcutaneous valve and device for externally setting it. Negre describes two micromagnets mounted in a rotor and locking means for locking the rotor in predetermined positions. The locking means described require internal device parts to move linearly to engage mechanical stops for locking the rotor in place. It may be desirable to avoid this type of mechanism since moving mechanical parts tend to decrease life of a product and increase mechanical wear. In addition, it is often desirable to design components which utilize or take up as little space as possible in implantable medical devices such as fluid flow control devices. The locking mechanism described by Negre may undesirably or unnecessarily utilize space for several reasons not the least of which may include by virtue of requiring the particular moving parts disclosed. Another disadvantage of this design is that biological debris is more likely to undesirably interfere with or jam the movable parts.

describes an implantable adjustable valve. describe a rotor for a valve unit where rotor magnets may have axes of magnetization arranged to lie at an angle relative to an axis of rotation of the rotor purportedly to achieve improved interaction with an indicator or adjustment tool. describes the angled axes of magnetization are achieved by physically tilting the magnets within the valve assembly such that the magnets themselves lie in a plane angled with respect to a flat or horizontal planar surface of the valve. Physically tilting or angling the magnets in the manner described by Wilson et. may also undesirably utilize space within a device. Adjustable valve assemblies are also.

The present invention provides a cartridge assembly as defined by claim Further aspects are defined in dependent claims <NUM>-<NUM>.

<FIG> depicts a fluid flow control device <NUM> which may be useful with devices and assemblies according to the present disclosure. Fluid flow control device <NUM> may be subcutaneously implanted in a patient (not shown) and may be percutaneously adjustable. Fluid flow control device <NUM> comprises an inlet connector <NUM> and an outlet connector <NUM>, each for receiving one end of a piece of surgical tubing (not shown). Inlet <NUM> is configured to fluidly connect to a catheter (not shown) which may be inserted through a patient's skull into a brain ventricle containing cerebrospinal (CSF) under pressure. The outlet connector <NUM> is configured to fluidly connect to a distal catheter which serves to direct CSF to another location in the patient's body. <FIG> depicts a cross-sectional view of the fluid flow control device of <FIG> taken along section <NUM>-<NUM>. Fluid flow control device <NUM> includes a fluid reservoir <NUM>, a valve mechanism <NUM> and a rotor assembly <NUM> described in further detail with reference to <FIG>. Also shown in <FIG> is an external tool <NUM> described further herein below.

<FIG> depicts an exploded view of the fluid flow control device <NUM> of <FIG>. Fluid flow control device <NUM> comprises a cartridge assembly <NUM> including a cartridge housing <NUM>, for housing a rotor assembly <NUM> (<FIG>). <FIG> depicts a three-dimensional partial view of the cross section of <FIG>. Valve mechanism <NUM> provides means for controlling fluid flow "F from the inlet connector <NUM> to the outlet connector <NUM>. More particularly, the valve mechanism <NUM> controls fluid flow "F" from a flushing reservoir <NUM> to a cartridge outlet fluid passageway <NUM>. The valve mechanism <NUM> includes a ball <NUM> which seats against a valve seat <NUM> to control the flow of fluid through a fluid passageway <NUM>. A pressure spring <NUM> is disposed below and in contact with the ball <NUM> to bias the ball <NUM> against the valve seat <NUM> to keep passageway <NUM> closed until a fluid pressure differential between the inlet <NUM> and outlet <NUM> exceeds a selected or desired valve opening pressure. Pressure spring <NUM> is supported at an end opposite the ball <NUM> by a first upper surface <NUM> of rotor assembly <NUM>. Rotor assembly <NUM> includes a magnet <NUM> or may include any of the magnets described herein below. Magnet <NUM> is provided within a base <NUM> which defines upper and lower surfaces <NUM> and <NUM>. The magnet or magnets <NUM> may be embedded or encapsulated in base <NUM>. <FIG> shows a top plan view of rotor assembly <NUM> including a base <NUM> with a single rotor magnet <NUM> embedded therein.

Returning to <FIG>, the lower surface <NUM> of rotor assembly <NUM> may include a single or multiple projections protruding from the lower surface <NUM>. For example, the lower surface <NUM> may include a single or multiple legs, tabs or feet. <FIG> depicts inner and outer legs <NUM> and <NUM> depicted in <FIG>, other configurations of a projection or projections are described below. Regardless, the projection or projections are configured to bear against either a single stair step array <NUM> (<FIG>) or a selected one of a plurality of inner and outer steps <NUM> and <NUM> of a fixed dual concentric stair-step array <NUM>. Rotor assembly <NUM> is configured to rotate in response to an applied magnetic field as described below.

The single <NUM> (<FIG>) or dual concentric stair-step array <NUM> allows adjustment of the amount of bias applied to the ball <NUM> in order to vary the selected valve mechanism <NUM> opening pressure. Lower surface <NUM> of the rotor assembly <NUM> is supported by the stair-step array <NUM>, <NUM> which interacts with the projection or projections (i.e., legs <NUM>, <NUM> in <FIG>) projecting from surface <NUM> to vary the relative height of the rotor assembly <NUM> with respect to the valve mechanism <NUM>. The dual concentric stair-step array <NUM> shown, for example in <FIG>, <FIG>, comprises a plurality of inner steps <NUM> surrounding the rotor pivot <NUM> and a corresponding plurality of outer steps <NUM> extending peripherally about the inner steps <NUM>. The inner and outer steps <NUM> and <NUM> are constructed so that those steps opposite to one another with respect to a central rotor axis A, subtend the same arch and are located at the same level.

The rotor assembly <NUM> includes a rotor magnet <NUM> which may include a single magnet (as shown) or dual magnets with horizontally aligned polarity or may comprise any of the magnets described herein below. An external magnetic tool or accessory <NUM> (<FIG>) may be used to adjust, locate or verify position of the rotor assembly <NUM>. Inner and outer legs <NUM>, <NUM> are illustrated in <FIG> and <FIG> as comprising nubs however, legs <NUM> and <NUM> may comprise other configurations such as projections having various shapes or may include other projections as described above.

It is to be understood that any of the fluid flow control device elements disclosed or described herein and/or depicted in the various embodiments herein including rotor assemblies, cartridges, cartridge housings, bases, magnets, and/or other housings or assemblies useful therewith, may be useful with fluid flow control device <NUM> or with any of the elements described herein. As but one example, rotor assembly <NUM> and cartridge housing <NUM> (<FIG>, <FIG>) may be used in lieu of or in place of rotor assembly <NUM> and cartridge housing <NUM> of fluid flow control device <NUM>. As another example, magnets <NUM> and <NUM> (<FIG>) could be used in lieu of or in place of magnet <NUM> or in place of magnets <NUM> and <NUM> (e.g., <FIG>) and so on. Likewise, any of the fluid flow control device elements disclosed herein may be useful in a variety of other fluid flow control devices (not depicted).

<FIG> depicts a cross-sectional top plan view of a rotor assembly <NUM> according to an embodiment. Rotor assembly <NUM> includes a housing or base <NUM> and two magnets, a first magnet <NUM> and a second magnet <NUM>, embedded in the base <NUM>. An outer ring <NUM> defines a lip around the circumference of the base <NUM>. Outer ring <NUM> is more clearly depicted in <FIG> which is a cross-sectional side view of the rotor assembly <NUM> of <FIG>. Ring <NUM> may include a lock-step tab <NUM> which may interact with a portion of a fluid flow control device to function as a stop to limit rotation of the rotor assembly <NUM> relative to the stair-step array e.g., <NUM> (<FIG>) to less than <NUM>°. However, ring <NUM> may be provided without a lock-step tab <NUM> in some embodiments. Inner legs <NUM> and outer legs <NUM> illustrated in the form of nubs, depend from a lower surface <NUM> of the base <NUM> and are configured to interact with a portion of a fluid flow control device <NUM> such as with a dual concentric stair step array e.g., <NUM> (<FIG>).

<FIG> is a three-dimensional view of rotor assembly <NUM> in which lock-step tab <NUM> can be seen projecting from outer ring <NUM>. Inner and outer legs <NUM>, <NUM> are depicted partially in phantom. Magnets <NUM>, <NUM> are also shown in phantom in base <NUM>. Magnets <NUM>, <NUM> may be mounted in or embedded in base <NUM> such that magnets <NUM>, <NUM> are positioned at various distances relative to one another within base <NUM>. Magnets <NUM>, <NUM> may be positioned in very close proximity such that magnets <NUM>, <NUM> are nearly in contact or are in contact with one another. Likewise, magnets <NUM>, <NUM> may be positioned with space (as shown) between magnets <NUM>, <NUM>.

First and second magnets <NUM>, <NUM> are each shown as comprising a five-sided polygonal shape (in a top plane or top cross-sectional view) with approximately straight edges or sides. However, magnets <NUM>, <NUM> may comprise any shape or combination of shapes including circular, semi-circular, spherical, hemispherical, elliptical, or polygonal, as but several examples. First magnet <NUM> and second magnet <NUM> may comprise substantially similarly shaped configurations and sizes or may each comprise a different one of the several shapes described above. Regardless, both magnets <NUM> and <NUM> are polarized in a vertical or substantially vertical direction i.e., substantially parallel to a central vertical rotor axis A' of rotor assembly <NUM> and polarity P1, P2 of magnets <NUM> and <NUM>, respectively, is oppositely aligned. Thus, as depicted by arrows P1 and P2, magnets <NUM> and <NUM> each comprise vertical polarity and comprise opposite or reverse polarity with respect to one another.

<FIG> shows a three-dimensional view of one magnet <NUM> apart from rotor assembly <NUM> depicting vertical polarity as described above. Magnet <NUM> is polarized in a vertical or substantially vertical direction indicated by arrow P1. Polarity P1 is vertical or substantially vertical with respect to a horizontal upper planar surface <NUM> of magnet <NUM>.

A rotor assembly (e.g., <NUM>) comprising magnets <NUM>, <NUM> which comprise vertical polarity P1, P2 in the manner disclosed may tend to resist aligning with a strong or nearby external magnetic field, such as during a magnetic resonance imaging (MRI) procedure since opposite alignment of the polarity P1, P2 of the magnets <NUM> and <NUM> effectively cancels the net tendency of the magnets <NUM>, <NUM> (and therefore the rotor or rotor assembly) to align with the external field. Thus, inadvertent pressure setting changes may be minimized or avoided while deliberate adjustment may still be carried out. Intentional or deliberate adjustment of the rotor assembly <NUM> to vary a valve opening pressure may be accomplished using an external adjustment tool (e.g., <NUM>, <FIG>) that simultaneously presents a tool magnet (not shown) comprising polarity configured in a complementary arrangement to the rotor assembly magnets <NUM>, <NUM>.

With reference between <FIG> and <FIG>, alternative embodiments of a rotor assembly and cartridge assembly will be described. <FIG> depicts a cartridge assembly <NUM> for receiving a rotor assembly <NUM>. As shown in <FIG>, cartridge housing <NUM> includes a cavity <NUM> configured to receive at least a portion of rotor assembly <NUM> whereby the cartridge housing <NUM> and rotor assembly <NUM> form a cartridge assembly <NUM> as depicted in <FIG>. Cartridge housing <NUM> includes a bottom surface <NUM> comprising a fixed dual concentric stair-step array <NUM> similar to stair-step array <NUM> described above. A central rotor pivot or axle <NUM> is configured to engage a central aperture <NUM> of rotor assembly <NUM> such that rotor assembly <NUM> may rotate about central rotor pivot <NUM> when rotor assembly <NUM> is positioned at various axial locations along central rotor pivot <NUM>. Inclusion of a central rotor pivot <NUM> may help to locate the rotor assembly <NUM> within cavity <NUM> and thus rotor pivot <NUM> aids in controlling the position of rotor assembly <NUM>. In addition, central rotor pivot <NUM> includes a central vertical pivot axis A" and may comprise at least one spline <NUM>. Central rotor pivot <NUM> may comprise any number of splines <NUM> i.e., may comprise a plurality of splines, for example two or more splines <NUM> with two splines shown in <FIG>. Splines <NUM> comprise a spline height "hs", a spline width, "ws" and a spline depth, "ds". Spline height "hs" may be less than a height "hp" of central rotor pivot <NUM> and spline width "ws" and depth "ds" may be any width or depth and may advantageously be small relative to a diameter "d" of central pivot <NUM>. Notwithstanding the above, in some embodiments, spline width "ws" and/or spline depth "ds" may be equal to or larger than rotor pivot diameter "d".

Where central rotor pivot <NUM> comprises more than one spline <NUM>, the spline height "hs" of each of the plurality of splines <NUM> may be the same or different. In other words, the height "hs" of splines <NUM> may be varied. The spline or splines <NUM> are configured to engage an at least one groove <NUM> on rotor assembly <NUM> (<FIG>) when the central aperture <NUM> of rotor assembly <NUM> is slid over the central rotor pivot <NUM> such that rotor assembly <NUM> is positioned at least partially in cavity <NUM> of cartridge housing <NUM>. As indicated above, coupling of the rotor assembly <NUM> with cartridge housing <NUM> creates a cartridge assembly <NUM>. Cartridge assembly <NUM> is configured for use with a fluid flow control device such as fluid flow control device <NUM>. The cartridge assembly <NUM> may be positioned within a fluid flow control device such that the rotor assembly <NUM> interacts with a valve mechanism <NUM> (<FIG>) to control the flow of cerebrospinal fluid in a patient's brain. A cartridge fluid outlet <NUM> is therefore configured to allow passage of CSF beyond the valve mechanism <NUM> and out of the device.

As depicted in <FIG>, rotor assembly <NUM> includes magnets <NUM> and <NUM> where magnets <NUM> and <NUM> may comprise rounded or curved sides (not shown). In this embodiment, magnets <NUM> and <NUM> are positioned in spaced relation about central aperture <NUM> of rotor assembly <NUM> and thus are spaced about central rotor pivot <NUM> when rotor assembly <NUM> is positioned within cartridge housing <NUM> as shown. Magnets <NUM> and <NUM> may be similar to magnets <NUM> and <NUM> described above such that magnets <NUM> and <NUM> comprise substantially opposed vertical polarity. However, magnets <NUM> and <NUM> may comprise horizontal polarity (e.g., described with reference to <FIG>, <FIG>) or may comprise a single magnet or magnets comprising angled polarization as described more fully herein below with respect to <FIG>. Additionally, rotor assembly <NUM> may comprise a single magnet (not shown) with a magnet aperture (not shown) for coupling to the rotor pivot <NUM>.

Rotor assembly <NUM> comprises at least one groove <NUM> in or along central aperture <NUM> and may comprise any number of grooves <NUM> i.e., may comprise a plurality of grooves, for example five grooves <NUM> as shown in <FIG> and <FIG>. Each groove <NUM> may have a size and shape which varies from one groove <NUM> to another, however, each groove <NUM> is configured to engage (e.g., via sliding over) each spline <NUM> of central rotor pivot <NUM>. The number of splines <NUM> and number of grooves <NUM> may differ, however, it may be desirable to include at least as many grooves <NUM> as splines <NUM>, i.e., there may or may not be more grooves <NUM> than splines <NUM>.

The rotor assembly <NUM> is configured to be placed at least partially within cartridge housing <NUM> whereby the groove or grooves <NUM> are configured to engage the spline or splines <NUM> such that inner and outer leg or legs <NUM> and <NUM> depending from lower surface <NUM> (<FIG>) of rotor assembly <NUM> are adjacent to, in close proximity, or in contact with the bottom surface <NUM> of cartridge housing <NUM>. As a point of reference, when legs <NUM>, <NUM> are in contact with the bottom surface <NUM>, legs <NUM>, <NUM> are in contact with the dual concentric stair step array <NUM>. Regardless of the proximity of surfaces <NUM> and <NUM>, as long as a groove <NUM> at least partially slides over or engages a spline <NUM>, rotor assembly <NUM> will be inhibited from rotating about central rotor pivot <NUM>. Thus, the at least one groove <NUM>, or plurality of grooves, is configured to engage the at least one spline <NUM>, or plurality of splines, such that rotation of the rotor assembly <NUM> about the central rotor pivot <NUM> is inhibited upon engagement. In this regard, the spline <NUM> and groove <NUM> configuration acts as a mechanical stop prohibiting inadvertent or undesired rotation of rotor assembly <NUM> about central rotor pivot <NUM>. This type of mechanical stop may be desired for example when, as described above, a fluid flow control device <NUM> (or rotor, rotor assembly or magnet of a device) is in the presence of an external magnetic field strong enough to cause alignment of the rotor assembly <NUM> with the external field but for the mechanical stop.

If rotation of the rotor or rotor assembly is desired, i.e., deliberate adjustment is desired or required, the rotor assembly <NUM> is configured to lift vertically or upwardly along the rotor pivot <NUM>. When the rotor assembly <NUM> is lifted vertically (upward) such that a lower end <NUM> of the at least one groove <NUM> is in spaced relation and is above an upper end <NUM> of the at least one spline <NUM>, the at least one groove <NUM> disengages the at least one spline <NUM> whereby disengagement allows the rotor assembly <NUM> to freely rotate about the rotor pivot <NUM>. The freedom to rotate about the rotor pivot <NUM>, as described above, allows adjustment of the valve setting.

<FIG> depicts an exploded view of another embodiment of a cartridge assembly, namely cartridge assembly <NUM>. Cartridge assembly <NUM> includes a cartridge housing <NUM> comprising a cartridge fluid outlet <NUM> similar to fluid outlet <NUM> described above. Likewise, housing <NUM> comprises a fixed, dual concentric stair-step array <NUM> similar to stair-step arrays <NUM> and <NUM> described above. Rotor assembly <NUM> may comprise any of the magnets described herein above and may for example comprise a single magnet or two magnets where the magnet or magnets may comprise vertical, substantially vertical or horizontal polarity and may comprise oppositely aligned vertical or angled polarity described with reference to <FIG>. Two outer legs <NUM> are shown in phantom and are similar to legs <NUM> and <NUM> described above. Cartridge housing <NUM> as depicted does not include a central rotor pivot as described above with reference to cartridge housing <NUM>, however, cartridge housing <NUM> may comprise a rotor pivot (not shown) similar to central rotor pivot <NUM> (<FIG>). Likewise, a central rotor pivot (not shown) may comprise at least one or a plurality of splines and/or grooves as described above with reference to <FIG>.

Housing <NUM> comprises at least one tab <NUM> on or adjacent an inner wall <NUM> of housing <NUM>. Housing <NUM> may comprise any number of tabs <NUM>, i.e., cartridge housing <NUM> may comprise a plurality of tabs <NUM>, for example two or more tabs <NUM>, with two tabs being shown in <FIG>. Tabs <NUM> may comprise a variety of shapes, sizes and configurations, the rectangular tab shown in <FIG> as but one exemplary embodiment. Tabs <NUM> comprise a tab height "ht", a tab width "wt" and a tab depth "dt" where "ht" may be less than a height "hw" of inner wall <NUM> and "wt" and/or "dt" may be relatively small compared to a width "wc" of cartridge housing wall <NUM>. Maintaining a relatively small width and/or depth "wt", "dt" of tabs <NUM> may advantageously require or consume the least or minimal amount of space in the cartridge assembly <NUM> which may be desirable for reasons described herein above. Accordingly, tabs may be considered low profile. Notwithstanding the above, alternatively, tab width "wt" and or depth "dt", may be equal to or greater than cartridge wall width "wc".

Where cartridge housing <NUM> comprises more than one tab <NUM>, the tab height "ht" of each of the plurality of tabs <NUM> may be the same or different. In other words, the height "ht" of tabs <NUM> may be varied. The tab or tabs <NUM> are configured to engage an at least one notch <NUM> on the perimeter of rotor assembly <NUM> when the rotor assembly <NUM> is positioned at least partially within cavity <NUM>' of housing <NUM>. The at least one notch <NUM> may comprise any number of notches <NUM>, i.e., may comprise a plurality of notches, for example nine notches <NUM> as shown (some in phantom) in <FIG>. Each notch <NUM> may comprise a variety of size and shapes which may vary from one notch <NUM> to another, however, each notch <NUM> is configured to engage (e.g., via sliding over) each tab <NUM> of cartridge housing <NUM>. The number of tabs <NUM> and notches <NUM> may differ, however, it may be desirable to include at least as many notches <NUM> as tabs <NUM>, i.e., there may be more notches <NUM> than tabs <NUM>. Rotor assembly <NUM> is configured to be placed at least partially within cartridge housing <NUM> whereby the at least one notch <NUM> is configured to engage the at least one tab <NUM> such that a lower surface <NUM> (or inner and outer leg or legs <NUM>, <NUM> depending from lower surface <NUM>) of rotor assembly <NUM> is adjacent to, in close proximity to, or in contact with the bottom surface <NUM> of cartridge housing <NUM>. Regardless of the proximity of surfaces <NUM> (or legs, <NUM>, <NUM>) and <NUM>', as long as a notch <NUM> at least partially slides over or engages a tab <NUM>, rotor assembly <NUM> will be inhibited from rotating within cartridge housing <NUM>. Thus, the at least one notch <NUM> is configured to engage the at least one tab <NUM> such that rotation of the rotor assembly <NUM> is inhibited upon engagement. In this regard, the tab <NUM> and notch <NUM> configuration acts as a mechanical stop prohibiting inadvertent or undesired rotation of rotor assembly <NUM> within cartridge housing <NUM>. This type of mechanical stop may be desired for example when, as described above, a fluid flow control device <NUM> comprising rotor assembly <NUM> is in the presence of an external magnetic field strong enough to cause alignment of the rotor assembly <NUM> with the external field but for the mechanical stop. If rotation of the rotor or rotor assembly is desired, i.e., deliberate adjustment is desired or required, the rotor assembly <NUM> is configured to lift vertically or upwardly with respect to surface <NUM>'. When the rotor assembly <NUM> is lifted vertically (upward) such that a lower end <NUM> of the at least one notch <NUM> is in spaced relation and is above an upper end <NUM> of the at least one tab <NUM>, the at least one notch <NUM> disengages the at least one tab <NUM> whereby the disengagement allows the rotor assembly <NUM> to freely rotate within cartridge housing <NUM>.

As with cartridge assembly <NUM>, coupling of the rotor assembly <NUM> with cartridge housing <NUM> creates cartridge assembly <NUM>. Cartridge assembly <NUM>, like cartridge assembly <NUM>, is configured for use with a fluid flow control device such as fluid flow control device <NUM>. Cartridge assembly <NUM> may be positioned within a fluid flow control device such that the rotor assembly <NUM> interacts with a valve mechanism <NUM> (<FIG>) to control the flow of cerebrospinal fluid in a patient's brain. A cartridge fluid outlet <NUM> is therefore configured to allow passage of CSF beyond the valve mechanism <NUM> and out of the device <NUM>.

With the above configurations of cartridge assemblies <NUM> and <NUM> in mind, rotation of a rotor assembly <NUM>, <NUM>, and thus adjustment of pressure settings of a fluid flow control device (e.g., <NUM>) in which the cartridge assemblies <NUM>, <NUM> may be placed, may be carried out deliberately via an external tool such as an adjustment tool <NUM>, described above. Adjustment tool <NUM> is configured to magnetically couple to a rotor magnet or magnets (e.g., <NUM>, <NUM>, <NUM>,<NUM>, <NUM>, <NUM>, <NUM> etc.) embedded in rotor assembly <NUM>, <NUM> to lift the rotor assembly <NUM>, <NUM> in the manner described above i.e., whereby an at least one groove <NUM> or notch <NUM> is raised above and disengaged from an at least one spline <NUM> or tab <NUM> permitting rotation of the rotor assembly <NUM>, <NUM> and therefore device pressure setting adjustment via adjustment of rotor assembly <NUM>, <NUM>. Once the desired rotation and thus pressure setting is achieved, rotor assembly <NUM>, <NUM> may be magnetically decoupled from the external tool <NUM> such that the at least one groove <NUM> or notch <NUM> is allowed to again or initially engage the at least one spline <NUM> or tab <NUM> and further rotation of rotor assembly <NUM>, <NUM> about central rotor pivot <NUM> or rotor assembly <NUM>, <NUM> within cartridge housing <NUM>, <NUM> is prohibited until disengagement of the spline or splines <NUM> from the groove or grooves <NUM> (in the case of rotor assembly <NUM>) or disengagement of the tab or tabs <NUM> from the notch or notches <NUM> (in the case of rotor assembly <NUM>) is again achieved.

<FIG> depict a rotor assembly according to another embodiment. Rotor assembly <NUM> includes a housing or base <NUM> having a central aperture <NUM> for engaging a central rotor pivot or axle <NUM> of cartridge housing <NUM> (<FIG>). Rotor assembly <NUM> includes a magnet <NUM> embedded in the base <NUM>. Magnet <NUM> comprises a single magnet having a groove <NUM> at one end and an arrow-shaped or pointed end <NUM> opposite the grooved end. This configuration of magnet <NUM> may aid in indicating a direction of fluid flow of a valve using imaging techniques such as x-ray or fluoroscopy. The polarization of magnet <NUM> is indicated by the arrow P5 which
shows a horizontal polarization with respect to the lower surface <NUM> of rotor assembly <NUM>. Alternatively, magnet <NUM> may include other magnet configurations as described herein and for example may include one or more magnets polarized in a vertical, substantially vertical or angled direction. In this embodiment, magnet <NUM> includes a magnet central aperture <NUM> aligned with the rotor central aperture <NUM>.

Rotor assembly <NUM> includes a protrusion <NUM> projecting downwardly from lower surface <NUM> of assembly <NUM>. Protrusion <NUM> comprises a stem portion <NUM> and a head portion <NUM>. However, protrusion <NUM> may include a variety of configurations and shapes, where the shape or configuration of the protrusion <NUM> is such that it is configured to engage with or fit within or between tabs or stops <NUM> of cartridge housing <NUM> (<FIG>). As indicated in <FIG>, protrusion <NUM> has a lower or bottom surface <NUM>, a length "PL", a stem portion width "Pw1" and head portion width "Pw2" as well as a protrusion height, "Ph" (<FIG>). The widths, length and height may be selected to provide a protrusion <NUM> which is substantial enough to provide the requisite resistance to inadvertent setting changes (described further below), while being sized sufficiently small so as to minimize space taken up by the rotor assembly <NUM>. The head <NUM> of protrusion <NUM> may include rounded corners, as shown, or may include other geometries or shapes.

As shown in <FIG>, protrusion <NUM> is positioned radially along base <NUM> such that protrusion <NUM> is substantially perpendicular to the angle of polarization P5 of magnet <NUM>. In other words, protrusion <NUM> is positioned radially about the perimeter of magnet <NUM> such that protrusion <NUM> is at a ninety degree angle to P5. Positioning protrusion <NUM> in this manner tends to minimize forces which would pull or lift the rotor out of a locked position. For example, when rotor assembly <NUM> is placed within cavity <NUM> of cartridge housing <NUM>, external forces acting on magnet <NUM> (e.g., if rotor <NUM> enters an MRI device at a substantially <NUM> degree angle to the magnetic field of the MRI equipment, as described above) may cause rotor assembly <NUM> to slightly rock back and forth along an axis perpendicular to P5. Since this "rocking" or tilting motion is not directly pulling up or acting on protrusion <NUM> (i.e. is not causing protrusion <NUM> to lift), despite the possible rocking or tilting motion described, the protrusion <NUM> tends to stay in a locked position between stops <NUM>. Even in light of the above, protrusion <NUM> may alternatively be positioned along base <NUM> at any radial location around the perimeter of magnet <NUM>.

<FIG> depict a cartridge housing in accordance with another embodiment and as described with reference to <FIG> above, may be particularly useful with rotor assembly <NUM>. Several features of cartridge housing <NUM> may be similar to other cartridge housings described herein. For example, cartridge housing <NUM> includes a cartridge fluid outlet <NUM> a central rotor pivot or axle <NUM>, and may include a generally similar outer housing profile. In addition, cartridge housing <NUM> includes a cavity <NUM> for receiving a rotor assembly such as <NUM>. When rotor assembly <NUM> is placed within cartridge housing <NUM>, the assembly may define a cartridge assembly (not shown) such as described with reference to cartridge assemblies <NUM> and <NUM>. However, one notable difference to other cartridge housings described herein is cartridge housing <NUM> includes a single stair-step array <NUM> as opposed to a dual concentric stair-step array (e.g., <NUM>). Since rotor assembly <NUM> includes only a single projection or protrusion <NUM>, only a single stair-step array <NUM> is provided. As with other stair-step arrays, stair-step array <NUM> includes five steps (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) corresponding to five settings of a fluid flow control device (e.g., valve <NUM>). The single-protrusion rotor assembly, single, stair-step array cartridge housing combination results in a design which may be easier to manufacture, and avoids relatively small, potentially fragile features.

As mentioned above, cartridge housing includes locks or stops <NUM> projecting inwardly from inner cartridge housing wall <NUM>. Each of locks <NUM> include an upper surface <NUM> where the upper surface <NUM> of each lock <NUM> lies in the same plane (e.g., as depicted in <FIG>). Locks <NUM> are positioned radially around inner wall <NUM> and five locks <NUM> are shown which correspond to the five stair steps of array <NUM>. Each individual lock <NUM> may include flattened edges <NUM> which angle inwardly as the lock <NUM> projects toward the rotor pivot <NUM>. This flat, angled configuration allows for stem <NUM> of protrusion <NUM> to have a line to line connection with the lock <NUM>, when the protrusion <NUM> is provided or located between two locks <NUM>. Additionally, upper edges <NUM> of lock <NUM> may be chamfered to provide a smooth transition of protrusion <NUM> along and over lock <NUM> when the protrusions <NUM> are deliberately lifted from a first position between two locks <NUM> to a second position between two other locks <NUM> such that protrusion <NUM> rests on a different stair step of the array <NUM> in each of the two positions. For example, protrusion <NUM> may rest on stair step <NUM> in a first position and may rest on stair step <NUM> in a second position, and so on.

<FIG> is a side cross-sectional view of cartridge housing <NUM> taken along line A-A. A portion of stair-step array <NUM> can be seen as well as several of locks <NUM>. <FIG> is a top view of cartridge housing <NUM> showing the arrangement of locks <NUM> around wall <NUM>. The rotor assembly <NUM> is configured to be placed within a cavity (e.g., <NUM>) of a cartridge housing, (e.g. <NUM>). Central rotor pivot <NUM> is configured to engage central aperture <NUM> of rotor assembly <NUM> such that rotor assembly <NUM> may rotate about central rotor pivot <NUM> when rotor assembly <NUM> is positioned at various axial locations along central rotor pivot <NUM>. However, the protrusion <NUM> is configured to fit between stops <NUM> of the housing <NUM> when the rotor assembly <NUM> is lowered into cavity <NUM> such that the bottom surface <NUM> of rotor assembly <NUM> is positioned lower than the upper surface <NUM> of stops <NUM>. When protrusion <NUM> is positioned between two stops <NUM> in this manner, rotor assembly <NUM> may be in a first, locked position and will be inhibited from rotating about central rotor pivot <NUM>. In this regard, the protrusion <NUM> and lock <NUM> interaction acts as a mechanical stop prohibiting inadvertent or undesired rotation of rotor assembly <NUM> about central rotor pivot <NUM>. This type of mechanical stop may be desired for example when, as described above, a fluid flow control device <NUM> (or rotor, rotor assembly or magnet of a device) is in the presence of an external magnetic field strong enough to cause alignment of the rotor assembly <NUM> with the external field but for the mechanical stop.

Conversely, if rotation of the rotor assembly <NUM> is desired, i.e., deliberate adjustment is desired or required, the rotor assembly <NUM> is configured to lift vertically or upwardly until the lower surface <NUM> of protrusion <NUM> is located above the upper surface of locks <NUM>. In this first, unlocked position, the rotor assembly <NUM> is free to rotate about the rotor pivot <NUM>. The freedom to rotate about the rotor pivot <NUM>, as described above, allows adjustment of the valve setting, for example, to a second, locked position (i.e., such that surface <NUM> or protrusion <NUM> rests on a step of the stair-step array <NUM> different from the step surface <NUM> rests on in a first, locked position).

<FIG> and <FIG> depict a rotor assembly and cartridge housing according to further embodiments. Rotor assembly <NUM> is similar to rotor assembly <NUM> with the exception of an additional projection, leg <NUM>, extending from lower surface <NUM> of base <NUM>. Leg <NUM> may comprise various shapes, configurations and sizes as long as leg <NUM> is sized for interaction with an inner stair-step array <NUM>" (having steps <NUM>', <NUM>', <NUM>', <NUM>', <NUM>') of dual-concentric stair-step array <NUM> (<FIG>). Protrusion <NUM> is similar to protrusion <NUM> described above and is likewise located perpendicular to the polarization of magnet <NUM>. Leg <NUM> is located adjacent or proximate central aperture <NUM>. Leg <NUM> interacts with inner stair-step array <NUM>", such as described above with reference to feet <NUM>, <NUM>, <NUM> of <FIG>. As with the dual-concentric stair step array <NUM>, stair-step arrays <NUM>', <NUM>" are constructed so that those steps opposite to one another with respect to a central rotor axis <NUM>, subtend the same arch and are located at the same level. Thus, lower surface or edge <NUM> of leg <NUM> lies in the same plane as lower surface <NUM> of protrusion <NUM>. Leg <NUM> interacts with inner stair-step array <NUM>", such as described above with reference to inner legs <NUM>, <NUM> etc. (<FIG>). Protrusion <NUM> is configured to interact with outer stair-step array <NUM>' (having outer stair steps <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and is configured to reside between stops <NUM> (<FIG>) similar to protrusion <NUM> and stops <NUM> such that when lower surface <NUM> of protrusion <NUM> is lower than an upper surface <NUM> of stops <NUM>, rotation of rotor assembly <NUM> about central rotor pivot or axle <NUM> is essentially prohibited while raising rotor assembly <NUM> such that the lower surface <NUM> is above upper surface <NUM> allows rotor assembly <NUM> to rotate about axle <NUM> so as to adjust the setting as described above.

<FIG> and <FIG> depict a rotor assembly and cartridge housing according to further embodiments. Rotor assembly <NUM> is similar to rotor assemblies <NUM> and <NUM>. Rotor assembly is similar to rotor assembly <NUM> in that two projections <NUM> and <NUM>, if coupled together, may resemble single projection <NUM> (<FIG>). Rotor assembly is similar to rotor assembly <NUM> in that the assembly includes two protrusion or projections, a tab <NUM>, and a stem <NUM>, extending from lower surface <NUM> of base <NUM>. Tab <NUM> may comprise various shapes, configurations and sizes as long as tab <NUM> is sized for interaction with an inner stair-step array <NUM>" (having steps <NUM>', <NUM>', <NUM>', <NUM>', <NUM>') of dual-concentric stair-step array <NUM> (<FIG>). A difference to rotor assembly <NUM> is tab <NUM> is spaced radially from (rather than adjacent to) central aperture <NUM>. Tab <NUM> interacts with inner stair-step array <NUM>", such as described above with reference to feet <NUM>, <NUM>, <NUM> and leg <NUM> of <FIG>, <FIG>.

Stem <NUM> is similar to protrusions or projections <NUM> and <NUM> described above in that stem <NUM> is likewise located perpendicular to the polarization of magnet <NUM>. Stem <NUM> is configured to interact with outer stair-step array <NUM>' (having outer stair steps <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and is configured to reside between stops <NUM> (<FIG>) similar to projections <NUM>, <NUM> and stops <NUM>, <NUM>. Lower surface or edge <NUM> of tab <NUM> lies in the same plane as lower surface <NUM> of stem <NUM>. Stair step array <NUM> is similar to array <NUM> although inner array <NUM>' may be radially wider than inner array <NUM>'. Thus, when lower surface <NUM> of stem <NUM> is lower than an upper surface <NUM> of stops <NUM> of cartridge housing <NUM>, rotation of rotor assembly <NUM> about central rotor pivot or axle <NUM> is essentially prohibited, while raising rotor assembly <NUM> such that the lower surface <NUM> is above upper surface <NUM> allows rotor assembly <NUM> to rotate about axle <NUM> so as to adjust the setting as described above.

The various rotor assemblies and cartridge housings described herein may comprise a variety of suitable materials such as suitable polymers. For example, rotor assemblies may comprise polysulfone and cartridge housings may comprise polysulfone, acetal, PEEK, polyphelylene, polyphenylsulfone, polyether sulfone, as but several non-limiting examples. Any suitable material may be used and may for example, include any material having a tensile strength high enough to prevent fracture of a central rotor pivot or axle (referenced generally).

<FIG> shows two magnets <NUM>, <NUM> useful with a rotor assembly e.g., <NUM>, <NUM>, <NUM>, <NUM>. The magnets <NUM> and <NUM> depict conventional horizontal polarization indicated at arrows P3 and P4. That is, each magnet <NUM>, <NUM> is magnetized in a plane horizontal to an upper planar surface <NUM>, <NUM> of the magnet. Stated another way, magnets are magnetized in a direction substantially perpendicular to a central horizontal magnet axis A1 or A2. <FIG> depicts two magnets <NUM> and <NUM> according to an embodiment. Magnets <NUM> and <NUM> comprise horizontal upper planar surfaces <NUM> and <NUM> which may be substantially flat. Magnets <NUM> and <NUM> also comprise horizontal magnet axes H1 and H2, respectively. In contrast to the horizontal polarity P3, P4 of conventional magnets <NUM> and <NUM>, magnets <NUM> and <NUM> comprise angled magnetization indicated at arrows P1' and P2', where the angle of polarization with respect to the horizontal magnet axes H1 or H2 may be any angle greater than <NUM> and less than <NUM> degrees. For example, the angle of polarization may be approximately greater than <NUM> and less than or equal to <NUM> degrees relative to horizontal magnet axes H1 or H2.

In the embodiment of magnet <NUM> shown, an angle of magnetization of <NUM> degrees is depicted. It is to be understood, however, that magnets <NUM>, <NUM> may comprise any angle of magnetization. Magnets <NUM> and <NUM> may be used in any of the rotor assemblies (e.g., <NUM>, <NUM>, <NUM>, <NUM>) described herein above or any other rotor assembly or fluid flow control device (e.g., <NUM>). Magnets <NUM> and <NUM> may be positioned or embedded in a rotor assembly <NUM>, <NUM>, <NUM>, <NUM>, cartridge housing <NUM>, <NUM> or fluid flow control device <NUM> such that horizontal planar surfaces <NUM>, <NUM> lie in a plane substantially perpendicular to a central vertical rotor axis or central vertical pivot axis A , A' or A" (<FIG>, <FIG> and <FIG>) of a rotor assembly <NUM>, <NUM>, <NUM> or cartridge housing <NUM>, <NUM> while magnetization or polarization of magnets <NUM>, <NUM> remains at an angle 'with respect to the horizontal magnet axes A, A' or A". In other words, magnets <NUM>, <NUM> themselves are not substantially or significantly tilted with respect to a base (e.g., <NUM>, <NUM>, <NUM>) or cartridge housing (e.g., <NUM>, <NUM>, <NUM>), rather, the magnetization or polarization of magnets <NUM>, <NUM> is "tilted" or angled by virtue of processing and/or manufacturing methods used in producing the magnets <NUM>, <NUM> which will be further described below. <FIG> describes an alternative embodiment where magnets <NUM> and <NUM> are similar to magnets <NUM> and <NUM> with the exception that the magnets are joined or coupled together and may thus form a single magnet.

Tilting or angling the magnetization or polarization P1', P2' of magnets <NUM>, <NUM> may allow for or result in stronger magnetic forces between an external device tool <NUM> and a rotor magnet or magnets e.g., <NUM>, <NUM>,<NUM>, <NUM> etc. when deliberate adjustment, location or indication of a pressure setting of a fluid flow control device, or shunt valve is desired. Tissues located between the site of implant of a fluid flow control device <NUM> and the area external to the patient in proximity to the implanted device may interfere with magnetic coupling or adequate coupling between a tool <NUM> and rotor assembly <NUM>, <NUM>, <NUM>. It has been found that angling the magnetization or polarization P1', P2' may advantageously produce higher magnetic forces between an external tool <NUM> and rotor magnets e.g., <NUM>, <NUM>, may provide better resistance to demagnetization, and when used with an axle or rotor pivot such as central rotor pivot <NUM> (<FIG>), may create additional friction in an MRI environment which may aid in resisting alignment with the MRI field. The higher forces between an external tool and rotor magnets is illustrated in the graph of <FIG> is a computer simulated plot of Force (in Newtons) versus a Magnetization angle (in degrees) from a horizontal magnet axis such as described above with reference to <FIG>. As illustrated in the plot, Force may be greatest where magnets comprise a magnetization angle between approximately <NUM> and <NUM> degrees.

In order to produce or manufacture magnets with angled polarization as disclosed above, the magnets <NUM>, <NUM>, <NUM>, <NUM> may be machined at an angle. Magnets in general and some magnets useful with fluid flow control devices are typically or conventionally machined with the grain of the magnetic material parallel to the magnet dimensions, such as illustrated by magnets <NUM> and <NUM> described above. If instead, and according to the disclosure, magnetic material is machined so that the grain of the material matches the desired polarization angle e.g., P1', P2', then the magnet or magnets (e.g., <NUM>, <NUM>) may be positioned in a rotor assembly (e.g., <NUM>, <NUM>, <NUM>) in a substantially physically flat (or horizontal as described above) configuration while maintaining angled polarity P1', P2' with the advantage of increased coupling strength, as described above, and a space saving design.

Claim 1:
A cartridge assembly for an adjustable fluid flow control device comprising:
a rotor assembly (<NUM>) comprising a base with a central aperture, a magnet mounted in the base and a protrusion extending from a lower surface of the base;
a cartridge housing (<NUM>) comprising a central rotor pivot configured to engage the central aperture, a stair-step array and a plurality of stops (<NUM>) each projecting from an inner wall of the cartridge;
wherein the rotor assembly is configured for placement at least partially within the cartridge housing and the protrusion is configured to be located between pairs of adjacent ones of said plurality of stops when resting on each step of the stair-step array, the protrusion configured to rest on a first step of the stair step array between two stops of the plurality of stops such that the rotor assembly is in a first, locked position in the cartridge housing with respect to the central rotor pivot; and characterized in that:
the rotor assembly is configured to magnetically couple to an adjustment tool (<NUM>) whereby the rotor assembly is configured to lift upwardly with respect to the stair-step array and the stops upon magnetically coupling with the adjustment tool; and
wherein the rotor assembly is configured to rotate about the central rotor pivot when the rotor assembly is lifted such that the lower surface of the protrusion is positioned above an upper surface of the plurality of stops.