Abstract:
A shunt for draining cerebral spinal fluid from the brain is provided. In an embodiment, the shunt includes a master control unit that is located in the abdomen, which interconnects a ventricular catheter and a second catheter, typically located in the peritoneal cavity. In a specific embodiment, the master control unit includes a variety of ‘smart’ features including at least one access port to allow the injection of solutions for the prevention or removal of blockages in the catheter, and/or antibiotics. The access port can have other uses, such as allowing a point of access for physical navigation of a catheter or the like within the shunt, thereby providing another option for breaking-up blockages, and/or allowing an access point for repairing the shunt&#39;s components. Additionally, the master control unit includes a diagnostic unit that transmits, either wirelessly or through a wired connection via the access port, diagnostic information about the status of the patient and/or the shunt.

Description:
PRIORITY CLAIM 
   This is a continuation of Application Ser. No. 09/942,223, filed Aug. 29, 2001, now U.S. Pat. No. 6,585,677, issued Jul. 1, 2003, the contents of which are incorporated herein by reference. 
   The present application claims priority from U.S. Provisional Patent Application No. 60/228,937 filed Aug. 30, 2000, the contents of which are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates generally to apparatuses for the treatment of hydrocephalus or the like, and more particularly relates to cerebrospinal fluid (“CSF”) shunts. 
   BACKGROUND OF THE INVENTION 
   CSF shunts are well known and used broadly to treat patients with chronic hydrocephalus. In simple terms, such shunts typically have an inlet located in the patient&#39;s brain, and an outlet into some portion of the body which can accept and expel the excess fluid. A detailed discussion of prior art CSF shunts can be found in Drake et al,  The Shunt Book, ©  1995 Blackwell Science, Inc. Massachusetts, (“Drake”) the contents of which are incorporated herein by reference. 
   More particularly, ventriculoperitoneal (“VP”) shunts are designed to drain CSF from the brain into the peritoneal cavity. VP shunts are used in a variety of medical conditions and are implanted in both young and old patients. Certain configurations of prior art VP shunts can include a ventricular catheter, a flow-valve that can be changed by an external magnet, and a tunneled abdominal catheter. Further discussion on this type of shunt can be found in Reinprecht A., et al., “The Medos Hakim programmable valve in the treatment of pediatric hydrocephalus.”,  Childs Nerv Syst,  1997 November-December; 13(11-12):588-93. The ventricular cather and flow-valve are inserted through a scalp incision. The major complications from these and other prior art shunts include infection, obstruction, disconnection, under draining, and over draining, all of which can lead to serious injury and even death. The symptoms of shunt failure and malfunction are nonspecific and include fever, nausea, vomiting, irritability and malaise. A patient presenting to a medical facility with such symptoms warrants a thorough radiological, laboratory, and occasionally a surgical evaluation. As known to those of skill in the art, insertion of CSF shunts requires a highly skilled surgeon or radiologist working under CT X-Ray guidance, but once inserted, such shunts are frequently prone to failure. 
   More recent shunts that attempt to overcome some disadvantages of older shunts include the use of telemetry, as discussed in Miyake H. et al., “A new ventriculpertoneal shunt with a telemetric intracranial pressure sensor: clinical experience in 94 patients with hydrocephalus”,  Neurosurgery,  1997 May; 40(5): 931-5 and Munshi H., “Intraventricular pressure dynamics in patients with ventriculopleural shunts: a telemetric study”,  Pedatr Neursurg,  1998 February; 28(2): 67-9 Despite the fact that Miyake and Munshi teach the use of telemetrics with shunts, the shunts taught therein are still prone to failure due to infection, blockages and other difficulties, such that failures of such shunts can still require complete replacement of the shunt. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a CSF shunt that obviates or mitigates at least one of the disadvantages of the prior art. 
   In an aspect of the invention, there is provided a shunt for draining cerebral spinal fluid comprising a first catheter for insertion into an area of the patient that has excess CSF, and for receiving CSF therefrom. The shunt also includes a second catheter for insertion into a drainage cavity for draining the CSF, and a master control unit for insertion into the patient in a biocompatible location. The master control unit interconnects the catheters via a catheter line, and has a regulator for selectively draining an excess of the CSF. The shunt also includes at least one access port intermediate the first catheter and the second catheter, and which is placed subcutaneously such that when the access port is inserted into the patient, the access port provides a point of access to the shunt for allowing a treatment a condition associated with the shunt without requiring the shunt&#39;s removal. 
   In a particular implementation of the first aspect, the CSF space is a ventricle. 
   In a particular implementation of the first aspect, the drainage space is one of the patient&#39;s peritoneum, pleural space or vascular space. 
   In a particular implementation of the first aspect, the biocompatible location is one of the patient&#39;s skull, chest cavity or abdomen. 
   In a particular implementation of the first aspect, the regulator is a mechanical flow-valve regulator. 
   In a particular implementation of the first aspect, the regulator is a microprocessor based valve-gauge assembly for determining when the CSF requires draining and allowing the CSF to drain from the ventricle to the drainage cavity. 
   In a particular implementation of the first aspect, the microprocessor based valve-gauge assembly has a normally-open position to allow a preset amount of drainage of CSF in the event of a power-failure to valve-gauge assembly. 
   In a particular implementation of the first aspect, the shunt further comprises a diagnostic unit for detecting abnormal metabolic activity within the patient, and a transmitter for delivering the activity to a receiver external to the patient. 
   In a particular implementation of the first aspect, the transmitter is operable to perform the delivery wirelessly to the receiver. 
   In a particular implementation of the first aspect, the transmitter includes a memory buffer for accumulating data from the diagnostic unit prior to the delivery, 
   In a particular implementation of the first aspect, the condition is a blockage and the at least one access port allows an introduction point of introduction of a blockage-ablation device within the catheter line for physically breaking-up the blockage. 
   In a particular implementation of the first aspect, the blockage-ablation device is a micro-catheter with a tip suitable for piercing the blockage. 
   In a particular implementation of the first aspect, blockage-ablation device is a radio-frequency ablation device. 
   In a particular implementation of the first aspect, the at least one access ports is mounted on an exterior of the master control, the control unit further having a fluid bladder accessible via the access port for injection of at least one solution for treatment of a condition. 
   In a particular implementation of the first aspect, condition a blockage and a solution for treatment thereof and injection via the access port is an anticoagulant or a thrombolytic. 
   In a particular implementation of the first aspect, the condition is an infection and a solution for treatment thereof and injection via the access port is an antibiotic. 
   In a particular implementation of the first aspect, the at least one access port includes a self-healing plastic membrane. 
   In a particular implementation of the first aspect, there at least two access ports and wherein one of the access ports is located on the catheter line intermediate the master control unit and the second catheter and wherein a second one of the access ports is located on the catheter line intermediate the first catheter and the master control unit. 
   In a particular implementation of the first aspect, the shunt further comprises a transmitter connected to the valve-gauge assembly for gathering pressure information therefrom, the transmitter for reporting the pressure information to a receiver external to the patient. 
   In a particular implementation of the first aspect, at least a portion of the shunt has an antibiotic coating. 
   A shunt for draining cerebral spinal fluid from the brain is provided. In an embodiment, the shunt includes a master control unit that is located in the abdomen, chest wall, in the skull, on the skull or other suitable location, which interconnects a first catheter and a second catheter that is typically located in the peritoneal cavity. In a specific embodiment, the master control unit is located in the abdomen, and includes a variety of intelligent features including at least one access port to allow the injection of solutions for the prevention or removal of blockages in the catheter, and/or antibiotics. Additionally, such ports can allow a radiologist (or the like) to navigate within the shunt to physically remove blockages or perform other remedial and/or diagnostic activities throughout the shunt system. Additionally, the master control unit includes a diagnostic unit that transmits, either wirelessly or through a wired connection via the access port, diagnostic information about the status of the patient and/or the shunt. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention will now be discussed, by way of example only, with reference to the attached Figures, in which: 
       FIG. 1  is a schematic representation of a CSF shunt in accordance with an embodiment of the invention; and, 
       FIG. 2  is a schematic representation of a CSF shunt in accordance with another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIG. 1 , a schematic representation of a CSF shunt is indicated generally at  20 . Shunt  20  comprises a master control unit  24  (which can also be referred to as the active component) that interconnects a first catheter  28 , and a second catheter  32  via a catheter line  34 . Master control unit  24  is preferably minitiarized and made of a biocompatible material such that it can be safely inserted in the patient&#39;s abdomen, either intra-peritoneal or extra-peritoneal, using a standard abdominal incision, and remain therein as needed to drain CSF. 
   After master control unit  24  is inserted into the patient&#39;s abdomen, first catheter  28  can then be tunneled from the abdomen rostrally (or caudaly) into a CSF space in the scalp to serve as an inlet for excess CSF, which in a present embodiment is a ventricle. (As used herein, the term CSF space includes any space in the body that can generate an excess of CSF requiring drainage.) A small incision in the scalp can then be used to assist in the final positioning of first catheter  28  within the patient&#39;s head. By tunneling into the scalp, it is contemplated that this can obviate the need to separately connect catheter  28  to control unit  24 . 
   Similarly, second catheter  32  can be tunneled from below, up into the peritoneal cavity to serve as an outlet for the CSF. The tip of second catheter  32  is chosen to increase the flow of CSF drainage, and to reduce the likelihood of obstruction thereat. In one embodiment, the tip of catheter  32  is static, having a conical shape with drainage ports along the surface and underside thereof. In another embodiment, the tip of catheter  32  is resiliently expandable, for breaking up debris, adhesions or other occlusions that can develop over time. A suitable expandable tip is an appropriately modified angioplasty balloon, which can be inflated to break up adhesions. 
   Master control unit  24  is powered by a battery  36  (or other self-contained power source), such as a high-capacity battery such as already widely used in pacemakers, stimulators, defibrillators and the like. It is presently preferred that battery  36  be located external to master control unit  24  and inserted in subcutaneous tissue to provide easy access for replacement in the event of failure. It is also contemplated, however, that battery  36  could be integrally housed within master control unit  24 . 
   Master control unit  24  is also characterized by a first access port  40  and a second access port  42 , which provide access to certain other components within shunt  20 , the details of which will be discussed in greater detail below. Thus, as master control unit  24  is inserted in the abdomen, is it also oriented within the patient subcutaneously, such that access ports  40  and  42  are readily accessible. Further, the placement of master control  24  is preferably particularly chosen to reduce the likelihood of rotation or other movement of master control unit  24 , to reduce the likelihood that ports  40  and  42  become inaccessible due to rotation or shifting in the patient over time. 
   Access ports  40  and  42  include a self-healing plastic membrane, which can be punctured with a sharp instrument (i.e. a needle, catheter, or the like) and then reseal itself upon withdrawal the instrument. Such self-healing plastic membranes can be adapted from currently available membranes used in vascular access devices and other applications requiring puncturing and resealing. 
   Master control unit  24  houses a first fluid bladder  44  proximal to first access port  40 , and a second fluid bladder  46  proximal to second access port  42 . Thus, when access port  40  or  42  is opened, the bladder  44  or  46  respective thereto, is accessible for filling via injection or for providing other access to shunt  20 . Bladders  44  and  46  are typically made of silicon or other biocompatible material. Such injections could include heparin (or some other anti-thrombotic or anti-collagen agent) and/or an antibiotic solution, such as for prophylaxis treatment or treatment of infection. Bladders  44 ,  46  are connected to catheter line  34  within control unit  24 , via a one-way valve  48 ,  50  respectively. Thus, for example, an injection into bladder  44  can eventually work its way into catheter line  34  (particularly the portion between control unit  24  and the second catheter  32 ) and thereby dissolve any blockages therein, without the need for more invasive surgery required to replace the entire shunt  24 . Alternatively, an injection may be desired to be eventually introduced into the patient, and using bladder  44  such an injection can be eventually introduced into the patient&#39;s peritoneal cavity. It will be understood by those of skill in the art that the size of bladder  44 , and the mechanical flow characteristics of valves  48  are chosen to allow an appropriate quantity and rate of delivery of the injection into line  34 . By the same token, access port  42 , bladder  46  and valve  50  can also provide access to shunt  20 , and in particular to the portion of shunt  20  between master control unit  24  and first catheter  28 , and in turn, the patient&#39;s skull. In other embodiments, it is contemplated that additional access ports, bladders and valves could be provided in order to provide additional means to introduce injections into shunt  20  and/or the patient in a manner with reduced intrusion to the patient. Where a patient is indicated for other injection therapies, such as chemotherapy, the present invention thus has the added benefit of providing means for introducing such injections without the need for vascular access devices. 
   Also housed within master control unit  24  is a microprocessor-based valve-gauge assembly  52 . Valve-gauge assembly  52  includes known components, including a pressure gauge for monitoring the pressure of CSF present in line  34 , and a valve for selectively allowing CSF to flow through line  34  and towards second catheter  32 . Valve-gauge assembly  52  also includes a ventricular-gauge  54  that is located proximal to ventricular-catheter  28  and connected to the portion of assembly  52  housed within master control unit  24  via a control line  56 , which is preferably inserted into the patient in conjunction with first catheter  28 . Accordingly, in certain configurations control line  56  can be physically connected in parallel to the portion of catheter line  34  that runs between first catheter  28  and master control unit  24 , thereby allowing control line  56  and that portion of catheter line  34  to be inserted simultaneously. 
   Valve-gauge assembly  52  further includes a microprocessor (or other processing means) that is operable to receive inputs from the pressure gauges associated with assembly  52  and to output control signals to the valve within assembly  52 . The microprocessor is programmed with various criteria that determine when the valve should be opened or closed. Any decision-making criteria that determines the appropriate and/or desired drainage of CSF from the ventricles (or other CSF space) to the peritoneal cavity (or other drainage space) can be used. For example, such decision making criteria could be based on different times of day. Additionally, valve-gauge assembly  52  could also be provided with an accelerometer or other movement sensor, and/or a mercury switch or other type of position sensor that provides additional feedback as to the movement and/or position of the patient. Such information can be included with the information provided by the pressure gauges of assembly  52 , as part of the decision making critera as to how much CSF drainage to allow. One known valve-assembly  52  that could be extended beyond its current functionality to incorporate the additional functionality described hereabove (and thereby provide a novel shunt over the prior art) is taught in Reinprecht, previously cited. 
   It is also presently preferred that the valve portion of valve-gauge assembly  52  be configured to be normally-open to provide a pre-set rate of flow of CSF in the event of a power failure of battery  36 . 
   Master control unit  24  additionally houses a diagnostic unit  60 , that includes a probe operable to sample CSF passing through line  34 , and the outer surface of line  34  to detect the presence abnormal metabolic activity within the patient. Diagnostic unit  60  can be based on any means for detecting such abnormal metabolic activity, such as a ph/Redox. Diagnostic unit  60  further includes a microprocessor for interpreting the data gathered by the probe, and, based on a predefined set of diagnostic criteria, make determinations as to whether shunt  20  is operating properly. Such diagnostic criteria would include, for example, whether the pH level of CSF flowing through unit  60  changes by a predetermined amount, thereby indicating the presence of infection. 
   The processing units of valve-gauge assembly  52  and diagnostic unit  60  are both connected to a transmitter  64 . Transmitter  64  is operable to receive information from valve-gauge assembly  52  and diagnostic unit  60  and emit that information to a computing device external to the patient. In a present embodiment, transmitter  64  operates wirelessly, emitting an RF signal detectable by a receiver located proximal to the patient. In order to reduce battery consumption, it is preferred that transmitter  64  emit at a low power level. The external computing device that receives the emitted signal can then use the information to either automatically to diagnose any malfunction or infection, and/or simply pass the data in human-readable format to the patient&#39;s doctor or other skilled professional for review and analysis. 
   Referring now to  FIG. 2 , in another embodiment of the invention there is provided a shunt  20   a . Like components in shunt  20   a  of  FIG. 2  to the components of shunt  20  of  FIG. 1  are given like reference numbers, followed by the suffix “a”. Thus, the components and operation of shunt  20   b  are substantially identical to the components of shunt  20 , except that in shunt  20   a  two additional access ports  70  and  74  are provided. Access port  70  is located along catheter line  34   a  intermediate first catheter  28  and master control unit  24 , while access port  74  is located along catheter line  34   a  at a point intermediate master control unit  24  and second catheter  32 . Access ports  70  and  74  are thus characterized by a chamber with an opening oriented towards the periphery of the patient&#39;s body, and covered with a self-healing plastic membrane, such as that previously described for access ports  40 ,  42 . 
   Thus, access ports  70  and  74  provide additional points for injection, similar to access ports  40  and  42 . Access ports  70  and  74  also provide a means for a radiologist (or the like) to use X-ray guidance in order to physically navigate items such as catheters, wires, radio-frequency blockage ablation devices, imaging devices based on fiber optics or ultra sound, within the various passageways of catheter line  34  and other components of shunt  20   a . In this manner, blockages within catheter line  34  can by physically broken up using a catheter to tunnel through such blockages within line  34 . Other uses for navigation within catheter line  34  will occur to those of skill in the art. 
   Shunt  20  can be placed in patient using traditional surgical techniques, or it can be placed using an image-guidance technique such as radiological, CT, MR, fluoroscopy, or the like. Additionally, each component of shunt  20  can be coated with, or made from a material that allows such component to be readily viewed using a complementary imaging system. For example, such components could be radio-opaque for viewing under X-ray. 
   While only specific combinations of the various features and components of the present invention have been discussed herein, it will be apparent to those of skill in the art that desired subsets of the disclosed features and components and/or alternative combinations of these features and components can be utilized, as desired. For example, the embodiments discussed herein refer to a fluid bladder, it will be understood that other means for injecting a solution can be provided. 
   Furthermore, while the embodiments discussed herein contemplate the placement of master control unit  24  in the abdomen, it is contemplated that master control unit  24  can be modified for placement in other suitable areas intermediate first catheter  28  and second catheter  32 , such as the chest wall (similar to a pacemaker) or in the skull. 
   It is also to be understood that the access ports  40 ,  42  of  FIG. 1  can also be used for physically accessing shunt  20  for repairing master control unit  24 , or for introducing a microcatheter or the like, in addition to using such ports  40 ,  42  for injections. 
   In addition, while not a requirement it is presently preferred that all or part of the components of shunt  24  are made from infection-resistant materials, such as using silicon tubing coated/impregnated with an antibiotic for catheter line  34 . 
   It is also contemplated that all or part of the various components of shunt  24  can be covered with an adhesion resistant coating. 
   While it is presently preferred to include microprocessor-based valve gauge assembly  52 , it is contemplated that in other embodiments of the invention such an assembly  52  could be replaced with another type of regulator, such as a traditional mechanical flow-valve currently found in CSF shunts, and thereby still provide an advantageous and novel shunt having access ports that can be used to treat conditions affecting the patient, such as those typically associated with the shunt&#39;s failure or infection of the patient, or the like. 
   While the embodiments herein teach the locating of first catheter  28  in the ventricles, it will now be apparent to those of skill in the art other types of receiving catheters for receiving excess CSF depending on the location from which the CSF is to be drained. 
   In addition, while the embodiments herein discuss the use of one-way valve  48  in conjunction with bladders  44  and  46 , in other embodiments it can be desired to incorporate different types of valves in order to allow aspiration, in addition to or in lieu of injection. For example, it can be desired to have one way valves  48  and  50  shown in  FIG. 1  replaced with two-way valves, and include a one-way way valve on the portion of catheter line  34  intermediate master control unit  24  and second catheter  32  in order to ensure that fluids only flow from master control unit  24  towards second catheter  32 —thereby freeing up ports  40  and  42  for use as aspiration ports. 
   It is also contemplated that transmitter  64  can be substituted for a transceiver, that would not only permit downloading of data from shunt  20  to an external computing device, but would also accept uploaded information to shunt  20  from an external computing device. Such uploaded information can include, for example, reprogramming instructions for software programming used in the operation of in valve-gauge assembly  52  and/or diagnostic unit  60 . 
   Furthermore, while the embodiments discussed herein refer to two access ports with associated bladders and other means to access catheter line  34 , in other embodiments it is contemplated that there may be only one access port, or more than two access ports, as desired. Furthermore, it is contemplated that such additional or fewer access ports could also be provided with additional bladders per access port, as desired. 
   Furthermore, while transmitter  64  of the embodiments discussed herein is wireless, it is also contemplated that transmitter  64  could function wirelessly, by attaching a data port, such as a serial port to transmitter  64 , that is accessible via port  40 . Further, it is also contemplated that transmitter  64  can include a memory buffer to allow an accumulation of data to be gathered, prior to downloading the data by transmission, and thereby providing a greater sampling of data without the need for interfering with the patient&#39;s mobility and/or relying on the patient&#39;s full-time proximity to a receiver to detect the transmission. 
   The present invention provides a novel shunt for draining CSF that has a main control unit that is located in the abdomen of the patient. The main control unit includes an access port that allows the injection of a solution into the shunt. Such a solution can include an anticoagulant or collagenase to treat an obstruction in the catheter. Other solutions can be injected, as desired. By providing one, two or more access ports, problems with the shunt can be addressed without the need for invasive surgery, such as removing and/or replacing the shunt. The access ports can also be used to allow physical navigation within the passageways of the shunt, thereby allowing repair of the shunt under radiological guidance, or to allow blockages to be broken-up under radiological guidance. Additionally, diagnostic functions are included within the shunt to provide information as to the operation of the shunt and/or information about the pressures and rates of drainage of CSF in the patient. Such diagnosis can also mitigate the need for invasive surgery, as can be required in certain prior art shunts, to ascertain the cause of a shunt failure. The shunt of the present invention can thus allow the diagnosis of shunt failure, and treatment thereof, without the need for additional surgery on the patient.