Abstract:
An anti-siphon drainage device having a housing forming an internal chamber, an inlet and outlet ports part of the internal chamber and fluidly connected by a primary flow path. A valve seat is associated with the primary flow path, a sloped section extends from the valve seat, and a valve element disposed in the sloped section and can seat in the valve seat to restrict a fluid flow into the primary flow path from the inlet port. A secondary flow path can have an opening near the inlet port and an orifice near the outlet port. A regulator has an aperture to selectively open and close the opening of the secondary flow path. When the valve element is seated in the valve seat and restricting the fluid flow into the primary flow path, the fluid flows into the secondary flow path.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. application Ser. No. 13/803,905, filed Mar. 14, 2013 (issuing as U.S. Pat. No. 9,050,436 on Jun. 9, 2015). This application is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a valve system for treating hydrocephalus. 
     BACKGROUND 
     Shunt systems for directing body fluid from one region to another are known in the medical field. One application for such a fluid shunt system is in the treatment of hydrocephalus in order to direct cerebrospinal fluid (“CSF”) away from the brain and into the venous system or to another region of the body. In this application, a shunt is implanted on the patient&#39;s skull, under the scalp, and is coupled to a brain ventricle catheter which is adapted for insertion into the brain and to a distal catheter which is adapted for insertion into the drainage region, such as the peritoneal cavity, the atrium or other drainage site. 
     The shunt systems typically include a pressure-regulated valve to control the flow rate of the CSF. The distal catheter is typically implanted caudal to the ventricular inlet which causes the shunt system to act as a siphon when the patent is in the upright position. The siphoning effect can cause overdrainage that can lead to low pressure headaches, slit ventricles, and subarachnoid hemorrhages. 
     Anti-siphoning has previously been addressed with several mechanisms, including weighted ball and seat valves, flow control valves, and diaphragm valves. In turn, the weighted ball and seat valves contain one or more balls or other mechanism, that when acted on by gravity, i.e. when the patient is upright, the ball seats in the valve passage and closes the fluid pathway. Closing a primary fluid pathway can lead to underdrainage if the alternate pathway does not provide sufficient drainage as well. Another ball and seat design closes in response to excessive flow, but offers a secondary pathway that always remains open, allowing for constant drainage, but the resistance of the secondary pathway remains fixed. Diaphragm valves are typically in the closed flow position and only opening in response to positive pressure and closing again when under negative distal pressure. A diaphragm valve has its disadvantages, in that it can become encapsulated by tissue and fails to open under positive pressure, this leads to underdrainage. 
     Examples of previous solutions include U.S. Pat. No. 4,605,395 to Rose et al. disclosing a single flow path ball and seat valve and U.S. Pat. No. 4,681,559 to Hooven, having two flow paths, but both have pressure valves. U.S. Pat. No. 6,126,628 Nissels is a pressure valve with a tortuous secondary flow path. However, the secondary flow path has fixed flow characteristics. Additionally, U.S. Pat. No. 8,177,737 to Negre et al. is a pressure valve with numerous secondary ports, but the flow to certain ports is controlled by the location of the ball in the primary flow path. Thus, the need exists for an anti-siphon valve of simple design, yet having multiple flow and pressure characteristics. 
     SUMMARY 
     Accordingly, the present invention provides tools and methods for simply controlling the siphoning effect caused by the implantation of certain shunt-systems. The examples of the present invention provide gravitationally assisted anti-siphoning valves wherein control over the siphoning rate is directly related to the number of open fluid passageways. Each secondary pathway can provide equal fluid flow resistance, such that each setting of the device is a multiple of the resistance of the single pathway. Alternately, each pathway can have its own unique resistance profile and flow is controlled by selecting the appropriate pathway. In one example, the user can select one or more pathway configurations to control the flow, without complex mechanisms that can potentially be obscured by tissue. 
     An anti-siphon drainage device can have a housing forming an internal chamber, inlet and outlet ports can be part of the internal chamber and fluidly connected by a primary flow path. A valve seat is associated with the primary flow path, a sloped section extends from the valve seat, and a valve element is disposed in the sloped section and can seat in the valve seat to restrict a fluid flow into the primary flow path from the inlet port. A secondary flow path can have an opening near the inlet port and an orifice near the outlet port. A regulator has an aperture to selectively open and close the opening of the secondary flow path. When the valve element is seated in the valve seat and restricting the fluid flow into the primary flow path, the fluid flows into the secondary flow path. 
     The anti-siphon drainage device can have the inlet port disposed approximately above the outlet port in a vertical direction, causing the valve element to enter the valve seat and restrict the fluid flow to the primary flow path. Contrary, when the inlet port is disposed approximately parallel the outlet port in a horizontal direction, the valve seat allows the fluid flow into the primary flow path. One of the valve element or the valve seat can allow a restricted fluid flow into the primary flow path when seated (i.e. a “leaky valve”). The disposition of the valve element in the valve seat can be controlled by gravity. 
     The primary flow path can be hydraulically larger than the secondary flow path. Some examples have the secondary flow path spiraled around the primary flow path. In others, they can be any shape or straight. 
     Another example of the anti-siphon drainage device can have a second secondary flow path separate from the secondary flow path having a second opening. The secondary flow path and the second secondary flow path can spiral around the primary flow path as a double threaded screw. The regulator can include a plurality of second apertures, which along with the aperture, are configured to selectively open and close the opening and the second opening. 
     A yet further example can also have a third secondary flow path separate from both the secondary flow path and the second secondary flow path, and having a third opening. The regulator now has a plurality of second apertures, which along with the aperture, are configured to selectively open and close the opening, the second opening, and the third opening. The regulator can have different settings to selectively open and close the opening, the second opening, and the third opening. The settings can have at least one of the following configurations: all open, all closed, each of the openings individually opened, and pairs of openings opened. 
     Furthermore, an example can have the primary flow path having a primary hydraulic capacity (P 1 ), the secondary flow path having a secondary hydraulic capacity (F 1 ), the second secondary flow path having a third hydraulic capacity (F 2 ), and the third secondary flow path having a fourth hydraulic capacity (F 3 ). The hydraulic relationship between them can be: F 1 &lt;F 2 &lt;F 3 &lt;P 1 . Alternately, the hydraulic relationship can be: F 1 &lt;F 2 &lt;F 1 +F 2 &lt;F 3 &lt;F 1 +F 3 &lt;F 2 +F 3 &lt;F 1 +F 2 +F 3 &lt;P 1 . 
     A method of forming an anti-siphon drainage device like that described above can include the steps of forming the primary flow path with the valve seat; disposing the valve element in the sloped section; forming the secondary flow path; and disposing the regulator over the secondary flow path to selectively occlude the secondary flow path. Forming the secondary flow path can include spiraling the secondary flow path around the primary flow path. The primary flow path can be formed with a first hydraulic characteristic, and the secondary flow path can be formed with a second hydraulic characteristic. In an example, the first hydraulic characteristic is greater than the second hydraulic characteristic. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention is described with particularity in the appended claims. The above and further aspects of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
       The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1  illustrates an example of the placement of an anti-siphon device of the invention relative to a fluid shunt system disposed in a patient; 
         FIG. 2  is an isometric view of an example of anti-siphon device in accordance with the invention; 
         FIG. 3  is a front view of the anti-siphon device without the housing in the secondary flow position; 
         FIG. 4  is a front view of the anti-siphon device without the housing in the primary flow position; 
         FIGS. 5A and 5B  are a top section view of the anti-siphon device illustrating an example of a regulator; 
         FIG. 6  is a cross-sectional isometric view of another example of an anti-siphon device; 
         FIGS. 7A and 7B  are a top section view of the anti-siphon device illustrating another example of a regulator; and 
         FIG. 8  is a table illustrating the apertures, secondary flow paths, and the flow resistance level. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. 
     Referring to the drawings, and particularly to  FIGS. 1 and 2 , a CSF anti-siphon pressure relief valve system  100  for maintaining a desired predetermined intracranial pressure in a patient P is illustrated. The system  100  includes an adjustable resistance, gravitationally activated, anti-siphon device  102  constructed in accordance with the present invention for maintaining a desired intracranial pressure. 
     Cerebrospinal fluid (CSF)  14  is drained from a ventricle  15  of the brain  16  by means of a ventricular catheter  17 . Preferably, the catheter is radio-opaque in order to facilitate its accurate placement within the brain. The distal end  18  of the catheter allows the passage of CSF therethrough and is positioned in a suitable brain ventricle. The other end of the catheter is coupled to an inlet port  104  of the anti-siphon device  102  to establish fluid communication between the system  100  and the ventricle. The outlet port  106  of the valve system is attached to one end of a drain catheter  23 , the opposite end of which discharges into an appropriate location in the patient&#39;s body. Although the drain catheter is shown threaded through an appropriate vein  24  to terminate within the right atrium of the heart  25 , a different drainage location, such as, for example, the peritoneal cavity, could be selected instead. When open, the system  100  allows passage of CSF from the brain ventricle to the selected discharge location to relieve excessive intracranial pressure caused by excessive accumulation of CSF. 
     While an increased differential pressure may result from the excessive accumulation of CSF in the brain ventricle, such an increase might also be a perfectly normal response to ordinary physical activity of the patient. For example, when a patient stands after lying for some time in a recumbent position, as illustrated in phantom in  FIG. 1 , the differential pressure will suddenly increase by reason of the sudden increase in vertical height H in the fluid column existing between the distal end of the ventricular catheter  17  and the drainage location. If a relief valve of the system were to open and permit unrestrained fluid flow in response to this pressure increase, overdrainage of the ventricle and a brain hematoma, are possible results. Further, the dimensions of the various parts described are selected so as to be compatible with subcutaneous implantation of the valve over the cranium  33 . 
     Referring to  FIGS. 2, 3 and 4 , an example of the adjustable resistance, gravitationally activated, anti-siphon device  102  according to the invention is shown. The device  102  includes an inlet  104  in the form of an aperture  108  disposed in a housing  110  and an outlet  106  in the form of a connector  112  suitable for coupling to a drainage catheter  23 . The housing  110  defines the inlet  104  at the proximal end of the device. The outlet  106  is at the distal end of the device  102  through which the fluid is directed from the device  102 . The components of the device  102 , including the housing  110 , are fabricated with any suitable biocompatible material. Examples of such preferred materials include polyethersulfone (PES), polysulfone (PS), polyurethane, polyethylene and polypropylene. 
       FIGS. 3 and 4  illustrate a partial section through the housing  110 . Through a midline  114  of the housing  110  is a primary flow path  116 . The primary flow path  116  connects the inlet port  104  to the outlet port  106  and is the main fluid path for the CSF. At a point in the primary flow path  116  a valve seat  118  is disposed in and stems from one end of the primary flow path  116  approximate to the inlet port  104 . Leading to the valve seat  118  is a sloped section  120 . The sloped section  120  can angle from the inlet port  104  to the valve seat  118 , where the narrowest section is at the valve seat  118 . Disposed within the sloped section is valve element  122 , which in one example can be a ball. Suitable materials for fabricating the ball  122  and seat  118  include synthetic ruby (aluminum oxide). 
     The valve element  118 , in one example, is not pressure sensitive. For example, the valve element  118  is not biased using a resilient element (e.g. a spring) to be unseated only when the pressure at the outlet  106  reaches a predefined threshold. In this example, the valve element  118  is displaced by gravity dictated by the orientation of the valve  102 . 
     When the housing  110  is in the upright position (i.e. the inlet port  104  is vertically higher than the outlet port  106 ) the ball  122  can be disposed in the seat  118  and the primary flow path  116  is sealed off by the ball  122  (see  FIG. 3 ). In one example, the primary flow path  116  is completely sealed to fluid flow. In other examples, the seal maybe “leaky” and deliberately allow a small amount of fluid to pass into the primary flow path  116  even though the ball  122  is seated properly. 
     The sloped section  120  can direct the ball  122  into the valve seat  118  when the housing  110  is in the vertical position. In examples, the sloped section  120  can be conical or frustoconical. In contrast,  FIG. 4  illustrates the device  102  is the horizontal position, and the ball  122 , by force of gravity, rolls down the sloped section  120  and out of the valve seat  118 . This clears the primary flow path  116  and allows fluid to flow freely. The horizontal and vertical positions of the device typically correspond to a horizontal or vertical position of the patient (i.e. laying down or sitting up). 
     The device  102  can also include one or more secondary flow paths  124 . The secondary flow paths  124  can transport fluid from the inlet  104  to the outlet  106  but are separate and distinct from the primary flow path  116  and in other examples are separate and distinct from each other. As an example,  FIGS. 3 and 4  illustrate two secondary flow paths  124   a ,  124   b  as a spiral path formed from a double threaded screw. However, the secondary flow paths  124  can take any form and any number. The opening  126  for the secondary flow paths can be within the sloped section  120  but outside the valve seat  118 . In one example, the ball  122  cannot seat in, and thus block, the secondary flow paths  124 . The secondary flow paths  124  can then discharge to the outlet port  106  through an orifice  140 . 
     Under primary flow conditions, as illustrated in  FIG. 4 , the primary flow channel  116  is open, because the ball  122  has rolled out, and the CSF preferentially flows through the primary flow path  116 . This is when the patent is typically prone.  FIG. 3  illustrates the secondary flow conditions when the patent is upright and gravity has placed the ball  122  into the seat  118 , sealing off the primary flow path  116 . In this condition, the fluid now must flow into the openings  126  of the secondary flow paths  124  to reach the outlet  106 . Sealing the primary flow channel  116  prevents siphoning, while having secondary flow paths  124  continues to allow for drainage. 
     In an example, each of the primary and secondary flow paths can have the same, similar or different hydraulic characteristics, for example, at least flow rates. The primary flow path  116  can be hydraulically larger than the secondary flow paths  124 . “Hydraulically larger” means that the primary flow path  116  can pass more fluid (i.e. a larger flow rate) than the secondary flow paths  124 , but this can be for various reasons. One reason can be that the primary flow path  116  has a larger diameter (flow rate=velocity×area) or has a smaller hydraulic resistance (also a factor of velocity and path geometry, along with other elements). A smaller hydraulic resistance allows the fluid to flow easier. Additionally, it can be a combination of these and other elements that allow a higher flow rate through the primary flow path  116 . 
     While, in certain examples, the ball  122  cannot block the secondary flow paths  124 , the secondary flow paths  124  can still be regulated.  FIGS. 5A and 5B  illustrate a secondary flow path regulator  128 . The regulator  128  can control the flow of fluid into the secondary flow paths  124  by partially or fully blocking the openings  126 . In this example, the regulator  128  has three apertures  130 . Two of the apertures  130  are illustrated in  FIG. 5A  as covering over both of the openings  126 . This is the maximum secondary flow condition. Also illustrated is a third aperture  130   a  offset from the other two apertures  130 . The regulator  128  can be rotated such that the third aperture  130   a  is over an opening  126 . It can seen in  FIG. 5B , that when the third aperture  130   a  is over one opening  126 , for flow path  124   a , the other opening  126 , and thus flow path  124   b , is occluded. One or either flow path  124   a ,  124   b  can be selected by rotation of the regulator  128 . Further, in certain examples, there can be partial occlusion. 
     Additionally, the regulator  128  can have a valve element opening  132 , allowing the valve element  122  unrestricted access to the valve seat  118 . In an example, the regulator  128  cannot affect or block flow to the primary flow path  116 . The purpose of the regulator  128 , in one example, is only to regulate the flow to the secondary flow paths  124 . 
     In certain examples, the regulator  128  is set by the surgeon prior to implanting the valve  102  into the patient. Particular rotations of the regulator  128  can result in differing secondary flow path rates and thus affect the intracranial pressure. Some valves can only be set by manual manipulation, which can require exposing the valve if the settings need to be changed once inside the patient. Other examples of the valve can have their settings changed without surgery. 
     Preventing flow into the primary flow path  116  when the valve  102  is upright prevents the siphoning effect. However, CSF still needs to be drained to prevent underdrainage. The secondary flow path  124  allows for continued drainage without a siphon effect. When the primary flow path  116  is opened (i.e. the valve element  122  is not seated in the valve seat  118 ) all or most of the fluid enters the primary flow path  116 . While the secondary flow path  124  is still open, the hydraulic characteristics of the primary flow path  116  are such that the fluid preferentially takes the primary path, as the path of least resistance. 
       FIGS. 6-7B  illustrate another example of an adjustable resistance, gravitationally activated, anti-siphon device  200 . The anti-siphon device  200  can have three secondary flow paths  224   a - c . Similar elements to the above example will be similarly referenced herein. The anti-siphon device  200  has an inlet  204  in aperture  208  form disposed in a housing  210  and an outlet  206  within a connector  212 . Through a midline  214  of the housing  210  is a primary flow path  216 . The primary flow path  216  connects the inlet port  204  to the outlet port  206  and is the main fluid path for the CSF. The primary flow path  216  can have a valve seat  218  disposed therein. Leading to the valve seat  218  is a sloped section  220  that can angle from the inlet port  204  to the valve seat  218 , where the narrowest section is at the valve seat  218 . Within the sloped section  220  can be a valve element  222 , which in one example can be a ball. 
     When the housing  210  is upright position the ball  222  can be disposed in the seat  218  and the primary flow path  216  is sealed.  FIG. 6  also illustrates a cross-section of two of the three secondary flow paths  224   a ,  224   b ,  224   c . In this example, the secondary flow paths  224   a ,  224   b ,  224   c  are straight and have openings  226   a ,  226   b ,  226   c  near the inlet  204  and flow into the primary flow path  216  at a point below the valve seat  218  through orifices  240   a ,  240   b ,  240   c.    
       FIG. 7A  illustrates the openings  226   a ,  226   b ,  226   c  of the three secondary flow paths  224   a ,  224   b ,  224   c . In this example, each flow path has a different flow characteristic. The first secondary flow path  224   a  (“F 1 ”) has the lowest flow rate, based on any of the factors mentioned above. The second secondary flow path  224   b  (“F 2 ”) has the next lowest flow rate, but greater than F 1 . The third secondary flow path  224   c  (“F 3 ”) has the largest flow rate of the secondary flow paths  224 , but still a lower flow rate than the primary flow path  216  (“P 1 ”). In relationship form: F 1 &lt;F 2 &lt;F 3 &lt;P 1   
       FIG. 7B  illustrates a secondary flow path regulator  228  to control the flow of fluid into the secondary flow paths  224  by partially or fully blocking the openings  226 . In this example, the regulator  228  has five to seven apertures  230 . The apertures  230  are spaced to allow any combination of secondary flow paths  224  to be set. Each individual secondary flow path  224   a ,  224   b ,  224   c  can be selected as well as combinations of secondary flow paths  224   a ,  224   b ,  224   c .  FIG. 8  illustrates an example of the eight different configurations three secondary flow paths of varying flow resistance can supply. The dark sections represent the apertures  230 . In this example the hydraulic capacity can be:
 
 F 1&lt; F 2&lt; F 1+ F 2&lt; F 3&lt; F 1+ F 3&lt; F 2+ F 3&lt; F 1+ F 2+ F 3&lt; P 1
 
     In both hydraulic capacity examples F 1  can have a value that 0&lt;F 1 . 
     A user selected flow configuration can reduce the number of anti-siphon devices kept in stock. Currently, the devices are preset from the factory with a particular secondary flow rate, and thus the above example of the present invention can replace up to eight prior art devices. Here, the user can preset the secondary flow rate on the current invention and then change his mind, and change the settings again and again. 
     A further example is a method to form the anti-siphon valve discussed above. The method can include forming the primary flow path with the valve seat and disposing the valve element in the sloped section. Next, the secondary flow path can be formed and the regulator can be disposed over the secondary flow path to selectively occlude the secondary flow path. 
     While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.