Patent Description:
A shunt may be inserted into a system for various purposes. Generally, a shunt allows transfer of a fluid, such as a liquid fluid, from a first location to a second location. A shunt may be used to bypass a pre-existing pathway or to create a new pathway in case of damage to a pre-existing pathway or non-existence of a pathway.

In various procedures, a shunt may be inserted into the anatomy of a subject, such as a human subject, to allow drainage of fluid, such as cerebral spinal fluid. Without drainage of cerebral spinal fluid, pressure may build in an enclosed area, such as within the cerebral ventricles, and cause damage to the brain of a subject. A shunt, therefore, may be provided to ensure an appropriate pressure be maintained within the cerebral ventricles of a subject.

A pressure monitoring system according to the state of the art is for instance described in <CIT>.

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of all of its features.

In some occasions, various processes may partially or fully occlude shunts placed in a subject. Such a malfunctioning or failed shunt will allow pressure to build and cause damage, such as to a brain of a subject. This damage may occur before signs or symptoms clinically present again in a subject. This damage may be temporary, long term, or permanent. To minimize this damage, real time pressure monitoring of cerebral spinal fluid in cerebral ventricles may be useful.

According to the invention there is provided a system as defined by claim <NUM>.

A pressure sensor may be provided with the shunt or catheter to assist in measuring the pressure at or near the location to be drained. The pressure sensor may be provided as a substantially small sensor that can be integrated onto a surface of a catheter, such as a plurality of traces formed on the surface or near a surface of a catheter, or as an independent sensor that can be integrated into the shunt or catheter. For example, the pressure sensor may be formed on a thin film and applied to the shunt or catheter. Further, the sensor may connect to circuitry to allow wired or wireless to transfer information transfer to selected systems, such as a surgical navigation system including a StealthStation® surgical navigation system and/or a monitoring system such as a CareLink® monitoring system both sold by Medtronic, Inc. , having a place of business in Minnesota, USA. Alternative systems, such as any wireless receiver system, including a portable computer system, may be used to receive incremental or bulk transfers of data including a pressure signal that includes values of pressure measurements. Further, the wireless systems may be either battery powered (i.e. including an on-board power system) or may be passive (e.g. including a radiative or inductive power system). Inductive or radiative power systems can include those disclosed in <CIT>.

With reference to <FIG>, a catheter <NUM> is illustrated. It is understood that a shunt may have a similar structure and may include various sensors, as discussed herein. Also, a catheter or a shunt may be generally referred to as an elongated instrument that may be hollow or includes a lumen <NUM>. It is understood, unless explicitly stated otherwise, that reference to a catheter, shunt, elongated hollow instrument is not meant to disregard similar structures unless specifically so stated.

The catheter <NUM> can extend from a distal terminal end <NUM> along a length to a proximal terminal end <NUM> that can be positioned in an appropriate system or portion of anatomy. Exemplary shunt systems include those sold by Medtronic, Inc. including the LP Shunt sold by Medtronic Neurosurgery, having a place of business in Goleta, California, and may further include various valves and flow controlled system, including Strata® valves, Delta® valves and other valve and flow controlled systems also sold by Medtronic, Inc. and/or Medtronic Neurosurgery. Further, the catheter <NUM> may be included as or provided as a catheter, including the Ares™ antibiotic catheter also sold by Medtronic Neurosurgery.

The catheter <NUM> may be inserted or positioned within the patient using various techniques such as with a stylet or elongated member <NUM> inserted into the catheter <NUM> via the proximal terminal end <NUM>. It is understood that reference to any specific tracked instrument is not intended to limit the discussion to a single or specific trackable instrument, but may relate to any disclosed herein, unless specifically stated otherwise. The proximal terminal end <NUM> may include an opening and may be an access to the lumen <NUM> extending partially or completely the length of the catheter <NUM> towards the distal end <NUM>. The catheter <NUM>, however, may be closed and sealed at the distal terminal end <NUM>. The stylet <NUM>, as discussed further herein, may also be used to assist in navigating using various surgical navigation techniques, as also discussed further herein. The stylet <NUM>, however, may provide selected rigidity to the catheter <NUM> during insertion of catheter <NUM> into the selected patient, or appropriate subject, including a non-living or non-human subject. As discussed above, the catheter <NUM> may be a catheter such as that generally known in the art, including the Ares™ catheter sold by Medtronic Neurological. Accordingly, various fixation mechanisms and clips may be provided that are movable or fixed relative to the catheter <NUM>, but are generally known in the art.

The catheter <NUM> includes an exterior wall <NUM> that has a maximum cross-sectional dimension 15a through which a wall portal or hole <NUM> may be formed. The holes <NUM> allow for ingress or egress of a fluid into the lumen <NUM> of the catheter <NUM>. The hole <NUM> may include a plurality of holes <NUM> that extend along a selected length, such as a length <NUM> of the catheter <NUM>. The length <NUM> may extend to the distal terminal end <NUM> or may be positioned proximal to the distal terminal end <NUM>.

Regardless, the holes <NUM> allow for a material to enter into the catheter <NUM> or exit the catheter <NUM>. According to various embodiments, including use of the catheter <NUM> with a cerebral spinal fluid shunt system, cerebral spinal fluid (CSF) may enter into a catheter <NUM> to be passed through the lumen <NUM> to a selected collection position. As is generally understood in the art, the collection point or exit from the lumen <NUM> may be into a flow control valve and then into a collection system, including an external bag or container, or positioned internally into a patient such as near the abdominal cavity within the peritoneum membrane.

Generally, it is selected to maintain a predetermined or selected pressure or pressure range within a ventricle within a brain inside of a skull cavity of a patient, as illustrated further herein. The determination of the pressure within the ventricle may be measured with a pressure sensor <NUM> positioned or formed on the catheter <NUM> that is positioned within the ventricle. The portals <NUM> and the catheter <NUM> allow for the CSF to move into the catheter <NUM> from the ventricle. Accordingly, the pressure sensor <NUM> positioned amongst the portals <NUM> or within the region or length <NUM> of the catheter <NUM> allow for the measurement of pressure in the same region from which the CSF is to be removed, including the ventricle.

The pressure sensor <NUM> may be interconnected with a monitoring system via a wire or connector <NUM> that may run along a length of the catheter <NUM>, such as to the proximal terminal end <NUM>. A length of wire or other connector may then interconnect with a selected monitoring or transmission system, as discussed further herein. Also, more than one of the pressure sensors <NUM> may be provided such as pressure sensors 30a and 30b in addition to the pressure sensor <NUM>. It is understood that each of the pressure sensors <NUM>-30b may be connected with a selected wire or conductor <NUM>, 32a, and 32b to a select data monitoring or transmission system. The connectors <NUM>-32b may be applied directly to the catheter <NUM>, including a surface thereof, or be provided on a printed circuit board integrated to the catheter <NUM>. The connectors <NUM>-32b may, however, be similar to those disclosed in <CIT>. Further, the pressure sensors <NUM>-30b may be identical or nearly identical except for location, including size, sensitivity, etc. It is further understood, that only one sensor <NUM> may be provided and/or that a signal is selected to be received or transmitted from only the one sensor <NUM>.

As illustrated in <FIG>, a most distal pressure sensor, including the pressure sensor 30a, is positioned a distance <NUM> from the distal terminal end <NUM>. Further, the other pressure sensors <NUM> and 30b are positioned more proximal of the distal most pressure sensor 30a. It is understood, however, that the pressure sensors <NUM>-30b may be positioned at any appropriate location along with the catheter <NUM>, including being positioned only within the length <NUM> or at other appropriate locations, as discussed further herein. The pressure sensors <NUM> may be located to maximize information relevant for navigation or long term monitoring, or both. Pressure sensors <NUM>-30b may be relevant to long term monitoring and may be placed as illustrated in <FIG>. Pressure sensors <NUM>'-30b' may be relevant to navigation and may include those at the shunt distal tip and at the proximal end of the holes as illustrated in <FIG>. It is understood, however, that all of the pressure sensors may be placed on a single device. As illustrated in <FIG>, the pressure sensor <NUM> may be formed on a surface <NUM> of the catheter <NUM>. The surface <NUM> may be an external surface, such as on the external wall <NUM>, and the pressure sensor <NUM> may be formed as a thin film <NUM> that may be placed on the surface according to various techniques. Further, the thin film <NUM> may include widths and lengths of about <NUM> millimeters (mm) to about <NUM> and a thickness of about <NUM> to about <NUM>. The thin films <NUM> may be connected to conductive traces, such as including widths of about <NUM> to about <NUM> that are laminated onto the surface <NUM> or may include vapor deposition techniques, or other appropriate forming techniques. Also, it is understood that the surface <NUM> may not be an external most surface, but may be overlaid with a selected material, such as polymer sheath or cover.

The pressure sensor <NUM>-30b, therefore, is to be provided such that a maximum cross-sectional dimension of the catheter 15a, especially within the length <NUM>, is increased by less than about <NUM>% when the pressure sensor is included. Generally, it is selected to include the increase in dimension to be less than about <NUM> to about <NUM>, including about <NUM>. Thus, the inclusion of the pressure sensor <NUM>-30b does not effectively increase the dimension of the catheter <NUM>. Thus, the catheter <NUM> that includes the pressure sensor <NUM>-30b may include substantially the same efficacy as previously used catheters, such as the Ares™ catheter.

Nevertheless, the pressure sensor <NUM> may be appropriately exposed to the environment external to or at the outer surface of the catheter <NUM> to be able to appropriately monitor pressure in an area, including the ventricle of a brain. Accordingly, the pressure sensor <NUM>, or the plurality of pressure sensors <NUM>, 30a and 30b may sense pressure at the location on the catheter <NUM> where they are placed and transmit the sensed pressure along the connectors <NUM>-32b for appropriate monitoring of the pressure within the ventricle or other selected position of the catheter <NUM> including the pressure sensors <NUM>-30b. As discussed herein, a wireless communication system may also be provided to transmit a signal from the pressure sensor <NUM>-30b.

Generally, the pressure sensor <NUM>-30b may measure a pressure at or near the holes <NUM> of the catheter <NUM>. The measured pressure may be pressure value that is transmitted as a pressure signal, wirelessly or wired. Pressure values may be determined in Torr, pounds per square inch, or other appropriate unit.

According to various embodiments, and with additional reference to <FIG>, a catheter <NUM>' is illustrated that may be substantially similar or identical to the catheter <NUM>. The catheter <NUM>' may also include a distal terminal end <NUM>' and a proximal terminal end <NUM>' and one or more ports <NUM> through an external wall <NUM>' of the catheter <NUM> to an internal lumen <NUM>' of the catheter <NUM>'. A maximum external cross-sectional dimension may also be defined generally within a length <NUM>'. The catheter <NUM>' may also include one or more pressure sensors <NUM>'-<NUM>'b, as illustrated in <FIG>. The position of the various pressure sensors <NUM>'-<NUM>'b, however, may be at different locations along the length <NUM>' including the ports <NUM>'.

As illustrated in <FIG>, the first pressure sensor <NUM>' may be positioned at a proximal extent of the ports <NUM>' and the third pressure sensor <NUM>'b may be positioned substantially across from or adjacent to the first pressure sensor <NUM>'. The second pressure sensor <NUM>'a may be positioned at or substantially adjacent to distal terminal end <NUM>'. The plurality of pressure sensors <NUM>'-<NUM>'b allow for measuring of pressure at both the distal end of the catheter <NUM>' and at a point substantially adjacent or immediately at the proximal extent of the ports <NUM>' generally defined by the distance <NUM>'. Accordingly, the catheter <NUM>', which may have a structure substantially similar or identical to the catheter <NUM>, may be able to provide measurements of pressure at different locations relative to the length <NUM> that includes the ports <NUM>' then the catheter <NUM> that includes the length <NUM> and the ports <NUM>. Nevertheless, it is also understood that the pressure sensors may be provided in any appropriate number and appropriate location relative to the catheter <NUM> for measuring the pressure relative to a selected portion of the catheter <NUM>, such as within the ventricle as discussed further herein.

The pressure sensors 30a-30b and/or <NUM>'-<NUM>'b may be formed on the surface of the catheter <NUM>, <NUM>' according to various known techniques. For example, a thin wire may be placed on the selected surface of the catheter <NUM>, <NUM>' to form the sensor. Also, the sensor <NUM> may be formed as a thin film and applied to the surface, as noted above. Exemplary sensors may include those disclosed in <NPL>). The surface on which the sensor is formed, however, may be an exterior sensor or an internal surface upon which the sensor may be formed. For example, the sensor <NUM>-30b or <NUM>'-<NUM>'b may be formed on an internal surface that forms the lumen <NUM>, <NUM>'.

According to various embodiments, as illustrated in <FIG>, however, a sensor assembly <NUM> may be provided which may be attached on an exterior surface or internally to a catheter <NUM>. The catheter <NUM> may be substantially similar to the catheters <NUM>, <NUM>' and may include portals <NUM>" along a length <NUM>" extending from a distal terminal end <NUM>" towards a proximal terminal end <NUM>". Further, the catheter <NUM> may include a lumen <NUM>" to which the holes <NUM>" allow fluid to flow. As discussed above, an external wall <NUM>" of the catheter <NUM> may also have a maximum external cross-dimensional measurement <NUM>" at least in the length <NUM>. A stylet <NUM>" may be placed in the lumen <NUM>", such as to stiffen the catheter <NUM> for insertion in a subject and/or navigation, as discussed further herein. Nevertheless, the catheter <NUM> may be provided for insertion into a selected subject including the sensor assembly <NUM>.

The sensor assembly <NUM> may be an appropriate sensor such as a micro or small pressure sensor sold by Phase IV Engineering, Inc. having a place of business located in Boulder, CO. The sensor assembly <NUM> may include a circuit board <NUM> onto which various components are assembled including a capacitor <NUM>, a processor system <NUM> (which may be encapsulated in an insulating material) and a sensor portion <NUM>. The sensor portion <NUM> may be interconnected with the processor system <NUM> to assist in analyzing a pressure signal created by the pressure sensor <NUM>.

The processor <NUM> may be any appropriate processor such as a general purpose processor executing instructions stored in a memory system and/or an application specific integrated circuit (ASIC) formed for the selected purpose of analyzing a signal from the pressure sensor <NUM>. Accordingly, the pressure sensor assembly <NUM> may be provided in a substantially small package generally including dimensions of about <NUM> by about <NUM>, and further including dimensions of about <NUM> by about <NUM>. The circuit board <NUM> may provide a framework for communication between the various components, including the capacitor <NUM>, the processor <NUM>, and the pressure sensor <NUM>. Further, interconnection may be provided to an antenna assembly <NUM>.

The antenna assembly <NUM> can allow for transmission of a signal from the pressure sensor assembly <NUM> to a selected receiver or controller, discussed further herein. The pressure sensor assembly <NUM> may, therefore, include a power source such as a battery to provide power for the processor <NUM>, other components, and the antenna <NUM>. Alternatively, or in addition thereto, the pressure sensor assembly <NUM> may include a passive power system that may receive a signal from an exterior source to provide power to the pressure sensor assembly <NUM>. According to various embodiments, the antenna assembly <NUM> may be at least a portion of an inductor circuit to allow for transmission of power to the pressure sensor assembly <NUM> from an external source via the antenna <NUM>. Therefore, the antenna <NUM> may both transmit a pressure signal including information regarding a value of a measured pressure sensed by the pressure sensor <NUM> and receive a signal to provide power to the pressure sensor assembly <NUM>.

Alternatively, or in addition thereto, a communication line or conductor <NUM> may also be provided to interconnect the pressure sensor assembly <NUM> with a selected transceiver or communicator. The conductor <NUM> may be similar to one or more of the conductors <NUM> discussed above to transmit the signal from the pressure sensor assembly <NUM> to a selected controller or receiver. The conductor <NUM>, therefore, can transmit a signal regarding the pressure sensed by the pressure sensor <NUM> of the pressure sensor assembly <NUM> for analysis and further processing.

The pressure sensor assembly <NUM> may be interconnected with the catheter <NUM> in appropriate techniques. For example, a sleeve or coating member <NUM> may be placed over the pressure sensor assembly <NUM> to adhere or fix the pressure sensor assembly <NUM> to the catheter <NUM>. The sleeve <NUM> may be formed of appropriate materials, such as Kevlar® polymer material, or other appropriate polymers. The sleeve <NUM> is generally provided to not interfere with the operability of the pressure sensor assembly <NUM> in determining a pressure near the catheter <NUM>. Further, the line <NUM> may be provided to capture or hold the sleeve <NUM> in place.

As illustrated in <FIG>, the pressure sensor assembly <NUM> may be positioned substantially near or at the distal terminal end <NUM>". It is understood, however, as discussed above in relation to <FIG> and <FIG> that the pressure sensor assembly <NUM> may be provided at any appropriate location along the length of the catheter <NUM>. Further, more than one of the pressure sensor assemblies <NUM> may be provided along the length of the catheter <NUM> such as generally within the length <NUM>" of the catheter <NUM>. Therefore, the pressure sensor assembly <NUM>, or any selected number of the pressure sensor assemblies <NUM>, may be provided to determine a pressure at selected positions along the length <NUM>" generally including the holes <NUM>".

According to various embodiments, as discussed above, determination of a pressure at a selected location or at a plurality of locations along the catheter <NUM>, <NUM>' or <NUM> can be determined. The determination of the pressures relative to the selected catheters <NUM>, <NUM>' or <NUM>, can be used to determine a pressure within a selected ventricle, such as a lateral ventricle within a patient. It is also understood that various other pressures may be measured such as a pressure in a spinal column, pressure near a heart, or other appropriate location. As discussed further herein, however, determining a pressure within a ventricle, such as a ventricle within a cranial cavity within a brain, can be used to determine efficacy of a shunt implanted into a subject for drainage or removal of CSF from the ventricle within the cranial cavity. Accordingly, the pressure sensors, including those discussed above according to various embodiments, can be used to determine efficacy and achieving a selected result of a shunt system to alleviate hydrocephalous.

In addition to the various embodiments discussed above, it is understood that various systems can be provided that may be integrated with the catheters, including the catheter <NUM>, <NUM>', <NUM>. Various sensors can include those disclosed by<NPL>). Additionally, pressure sensors can include those sold by MC10 Inc. , having a place of business in Cambridge, Massachusetts. The sensors sold by MC10 may be integrated directly into or onto thin elastic membranes of conventional instruments, such as balloon catheters or flexible shafts. Additionally, sensors, such as the sensor assembly <NUM>, may include micro, miniature, or ultra-miniature passive wireless sensors sold by Phase IV Engineering, Inc. , having a place of business in Boulder, Colorado. Other sensors may be adapted from Positive ID Corporation including the Glucochip™ assembly that includes an integrated antenna.

Further, in addition to the specific sensors as exemplarily discussed above, various coils may be provided to allow for induction to power the various sensors. For example, Metrigraphics, having a place of business in Wilmington, Massachusetts, sells flexible micro-circuits including the single layer and multilayer flexible circuits that may be provided in an appropriate antenna size to allow for induction. Tech-Etch, Inc. having a place of business in Plymouth, Massachusetts, also as provides flexible circuits that may be used as antennas. Accordingly, the coils, such as the flexible circuit coils may be used to power the sensors as discussed further herein.

Generally, it is selected to have a pressure sensor that is small. Thus, the small sensor may be integrated into the catheter and the catheter may have a dimension no greater than the dimension of the generally provided catheter, including the Ares® catheter sold by Medtronic Neurological. That is, the sensor is generally selected to be provided on the catheter, such as the catheter <NUM> and/or the catheter <NUM> without increasing or substantially increasing the external dimensions of the catheter as generally sold without a sensor. Accordingly, it may be selected to have the sensor be provided on the catheter without increasing the dimensions of the catheter more than about <NUM>% or more than about <NUM>% or <NUM>% relative to a catheter not having any pressure sensors. This may include increasing the dimensions of the catheter no more than <NUM>%. The dimension that is selected to be maintained is the cross-sectional maximum dimension, such as at least within the length <NUM>, <NUM>', <NUM>". Further, it is generally selected to have the sensor have as close to zero or zero drift over time. That is, that the pressure sensor may be calibrated prior to placement or implantation and the calibration would vary or the measurement would vary less than about <NUM>% to about <NUM>%, including about <NUM>% over a selected lifespan of the pressure sensor. As a further example, it may be desirable to have less than a <NUM>% drift in a pressure measurement over five year lifespan of an implanted catheter.

The various pressure sensors provided on the catheters, including the catheters <NUM>, <NUM>', and <NUM> may be used for various purposes, such as measuring pressure within a ventricle. As discussed above, the catheter may be positioned within a ventricle of a patient as schematically illustrated in <FIG>. As exemplarily illustrated in <FIG>, the catheter <NUM> may be positioned within a lateral ventricle <NUM> of a brain <NUM> of a subject <NUM>. The subject <NUM> may be any appropriate subject, such as a human subject, including a human child or adolescent. In certain instances, the CSF may not drain from the ventricles, including the lateral ventricle <NUM> within the brain <NUM> of the subject <NUM>, causing hydrocephalous. In these instances, a shunt and/or catheter system, which may include the catheter <NUM>, may be implanted within the lateral ventricle <NUM> to provide a pathway for CSF to flow from the lateral ventricle <NUM> out of the brain <NUM>.

In various procedure examples, the catheter <NUM> may be interconnected or connected to a valve <NUM>, which may be the Strata® valve sold by Medtronic Neurosurgery. It may be selected, however, but the valve may not be included for various purposes. Further, the valve <NUM> may have an inductive antenna <NUM> associated therewith, such as placed on a surface of the valve <NUM>. Generally, the valve <NUM> may be placed near a skin surface of the subject <NUM>, thus inductive coupling may be more efficient. The conductive traces, such as the traces <NUM>-32b may then transfer the power to the sensors <NUM>-30b. Accordingly, inductive power antennas need not be placed directly with the sensors <NUM>-30b, or other appropriate pressure sensors.

The catheter <NUM> may further be interconnected with a drainage cannula <NUM> that may be positioned in an appropriate portion of the subject <NUM>, such as near the abdomen in the peritoneal cavity <NUM>, as discussed above. Also it is understood that the cannula <NUM> may be interconnected with an external collection system or package rather than draining internally into the subject <NUM>. As is generally understood in the art, hydrocephaly causes pressure on the brain <NUM> due to the buildup of fluid within the ventricles, including the lateral ventricle <NUM>, and presses the brain <NUM> against a skull <NUM> of the subject <NUM>. Accordingly, providing passage for the CSF from the lateral ventricle <NUM> out of the brain <NUM> can reduce or eliminate the effects of hydrocephaly.

If the catheter <NUM>, or portions of the drainage system become clogged or the increase of CSF is greater than originally designed parameters, pressure may increase within the lateral ventricle <NUM> above a selected, such as a predetermined, value. Such a malfunctioning or failed shunt will allow pressure to again build and possibly cause damage to the brain of the subject <NUM>. This damage may occur before signs or symptoms clinically present again in the subject <NUM>. This damage may be temporary, long term, or permanent. To minimize this damage, real time pressure monitoring of cerebral spinal fluid in cerebral ventricles may allow for early detection and treatment prior to damage. Therefore, the pressure sensors, including those discussed above, may be provided on the catheter <NUM>, or any of the appropriate catheters discussed above according to various embodiments, to monitor the pressure within the lateral ventricle <NUM> or in other appropriate positions where the catheter <NUM> is implanted. It is understood that discussion of the catheter <NUM> herein, as an example, is not intended to disregarded the other disclosed catheters unless specifically so stated. Similarly, discussion of the pressure sensor <NUM> is not intended to limit the disclosure to only that pressure sensor and not the other pressure sensors including disclosed embodiments, unless specifically stated.

Generally, as discussed above, the catheter <NUM> may include a pressure sensor positioned thereon. The pressure sensor, such as the pressure sensor <NUM>, may measure a pressure at the sensor <NUM> and the pressure may be recorded over time as a pressure value. Further, as discussed above, the communication with the pressure sensor <NUM> may be wireless. Alternatively, or in addition thereto, the communication may be wired. Regardless, a receiver and/or transmitter (transceiver) <NUM> can be provided to be positioned near the catheter <NUM> in the implanted position, such as within or under a pillow <NUM> and/or within or under a bed or patient support. The subject <NUM> may lie on the pillow <NUM> and the transceiver <NUM> may receive the pressure signals from the pressure sensor <NUM> positioned in the lateral ventricle <NUM>.

If the pressure sensor <NUM> is wireless, the transceiver <NUM> may transmit a signal to power the induction antenna, as discussed above, and/or may transmit a signal to indicate that the pressure sensors transmit a signal if an internal battery is provided. Alternatively, the transceiver <NUM> may be physically connected, such as with the leads or conductors <NUM> to transmit the pressure signal to the transceiver <NUM>. The transceiver <NUM> may be an appropriate transceiver such as the transceiver CareLink® Reader sold by Medtronic, Inc. Generally, the transceiver <NUM> may receive a pressure signal from the pressure sensor <NUM> and transmit it via a communication line <NUM> to a workstation <NUM>.

The workstation <NUM> may receive the pressure signal from the transceiver <NUM> that is received from the pressure sensor <NUM>. The communication line <NUM> may be a wired data transmission line and/or a wireless transmission (e.g., Bluetooth® communication protocol). The workstation <NUM> may allow the user to select the times and frequency of monitoring by the pressure sensor <NUM>. Thus, the pressure sensor need not constantly measure the pressure. This may be a power saving routine. Also, if the pressure sensor <NUM> is passively powered, it may only measure when a user instructions the transceiver <NUM> to emit the power signal. Thus, measuring of the pressure may be continuous or at any selected frequency.

The workstation <NUM> may be an appropriate workstation, such as a portable computer (such as a portable or handheld workstation <NUM>), terminal for a networked processor, or any other appropriate workstation. Nevertheless, the workstation <NUM> may include a processor <NUM> and a memory system <NUM>. The processor <NUM> may be an application specific processor, such as an application specific integrated circuit. Alternatively, or in addition thereto, the processor <NUM> may be a general processor that is configured to execute instructions, as discussed further herein. Instructions may be stored on the memory <NUM> which may be any appropriate type of memory such as a read/write memory, random access memory, local memory, or remotely connected memory. Further, sensor information or data from the sensor <NUM> may be stored on the memory <NUM> for later retrieval and/or processing. The workstation <NUM> may further include a display <NUM> to display information, such as a graph <NUM> of the pressure measurements over time. Further, the workstation <NUM> may include a user input such as a touchscreen display, a pointer device, or other appropriate inputs.

The transceiver <NUM> used with the workstation <NUM> can provide an external measuring and/or analysis system which may be generally referred to as a pressure analysis system. Further, it is understood that the transceiver <NUM> may be integrated into the workstation <NUM> and the workstation <NUM> with the integrated transceiver <NUM> may be positioned close enough to the catheter <NUM> to receive a transmission of a pressure signal from the pressure sensor <NUM> on the catheter <NUM>. In this way, the workstation <NUM> may provide a compact and efficient system for receiving the pressure signals from the pressure sensor <NUM> to provide for analysis thereof.

In various embodiments, the workstation <NUM> may include a handheld portable device such as an iPhone® communication system, or similar device. A user, such as a nurse, doctor, or the like, may position the handheld device exemplarily illustrated as <NUM> in <FIG>, near the subject <NUM> to receive a pressure signal from the pressure sensor <NUM> on the catheter <NUM>. The pressure signal may be transmitted wirelessly, which is schematically illustrated as transmission <NUM>, such as via a Bluetooth® wireless transmission protocol. The transmitted signal may be analyzed by an onboard processor or a remote processor for viewing an instantaneous and/or graphed pressure value <NUM> on a display <NUM> of the handheld device <NUM>.

According to various embodiments, therefore, the workstation <NUM>, which may be embodied as a handheld device <NUM>, may be used to view a pressure value sensed by the pressure sensor <NUM> on a catheter <NUM>. This can allow a user to monitor pressure in the lateral ventricle <NUM>, or other appropriate location, to ensure that the appropriate pressure, such as a predetermined pressure, is being maintained within the brain <NUM> of the subject <NUM>. The predetermined pressure may be a single value, a range of values, or a single value with a threshold range (e.g. plus or minus the selected predetermined value).

As discussed above, hydrocephaly may increase pressure in the brain <NUM> within the skull <NUM>. Such increased pressure may manifest itself as headaches or other trauma to the patient. Prior to trauma occurring to the patient, however, a pressure may generally increase within the skull <NUM>, such as within the lateral ventricle <NUM> to a level that is pre-traumatic but higher than a predetermined or preselected value. Accordingly, a monitoring, such as constant or at a selected frequency or time, such as with a workstation <NUM>, can allow for a determination that the pressure is increasing to an undesirable or unselected level and intervention may occur prior to trauma occurring to the subject <NUM>. Therefore, any monitoring with the workstation <NUM>, and also the handheld workstation <NUM>, may lead to an output to a user, such as an alarm being sounded or provided to a selected individual, such as a nurse or doctor. For example, a text message, audible alarm, color alarm, or other alarm may be provided to indicate that the pressure measured by the pressure sensor <NUM> on the catheter <NUM> is above or outside of a selected range.

Turning reference to <FIG>, the catheter, including catheter or stent <NUM>, <NUM>' discussed above, may be positioned within the subject <NUM> with a navigated instrument. The navigated instrument may include a tracking device or element <NUM>' positioned directly on the catheter <NUM>, or a catheter according to any various embodiment, or may be included with the stylet <NUM>. Tracking devices may include electromagnetic tracking devices including coils of wire, conductive materials, or the like, formed on the catheter <NUM> or on the stylet <NUM>. According to various embodiments, the stylet <NUM> may include a tracking device <NUM> formed near a distal end of the stylet <NUM>. The stylet <NUM> may be placed within the lumen <NUM> of the catheter as illustrated in <FIG>, and further in <FIG>.

The tracking device <NUM> may be interconnected with a navigation system <NUM>, as illustrated in <FIG>. The navigation system, as discussed further herein, may include a tracking system <NUM> that can track the tracking device <NUM> in space including a three-dimensional X,Y,Z position and three-dimensional pitch, yaw, and roll orientation to determine a position and orientation of the tracking device <NUM> in space. The stylet <NUM> can be rotationally and axially fixed within the catheter <NUM> to allow for a determination of a portion or all of the catheter <NUM>, including the portion adjacent to the tracking device <NUM>. Alternatively, the catheter <NUM> may include the tracking device <NUM>' that allows for directly tracking the catheter <NUM> during an implantation and positioning of catheter <NUM>. Appropriate tracking devices can include tracking devices as disclosed in <CIT>. Additionally, the navigation system can include the navigation system disclosed in <CIT>.

With continuing reference to <FIG>, the catheter <NUM> may be inserted into the patient <NUM> via an opening or bore <NUM> in the skull <NUM> of the subject <NUM>. The bore <NUM> may be a burr hole formed through the skull <NUM> as generally understood in the art. The catheter <NUM>, tracked either directly via the tracking device <NUM>' or via the tracking device <NUM> on the stylet <NUM>, can then be inserted into the hole <NUM>. The navigation of the catheter <NUM> relative to the subject <NUM> may proceed according to various navigation procedures and techniques, such as those generally known in the art and discussed below, to ensure or assist in positioning the catheter <NUM> in a selected, including a predetermined or preselected location, within the subject <NUM>. Further, although the following description is related generally to positioning the catheter <NUM> within a lateral ventricle of the brain <NUM>, it is understood that catheter <NUM> may be positioned to any appropriate location to assist in movement or transport of liquid from one location to another.

The navigation system <NUM>, which may include an electromagnetic navigation system, is primarily described with respect to performing a procedure on a human patient, the navigation system <NUM> may be used to perform a procedure on other animate and/or inanimate subjects, including those navigation systems as disclosed in <CIT>. Also, procedures disclosed herein can be performed relative to a volume, a mechanical device, and/or an enclosed structure. The volume may be of an animate or inanimate object. The subject can be an object that includes an enclosed mechanical device.

The navigation system <NUM> assists in performing a navigated or guided procedure. The guided procedure can be, for example, a surgical procedure, a neural procedure, a spinal procedure, and an orthopedic procedure. The navigation system <NUM> allows a user, such as a surgeon <NUM>, to view on a display <NUM> a position of an instrument, such as the catheter <NUM>, or other appropriate instrument that may be tracked in a coordinate system. The coordinate system can be related to an image, such as in an image guided procedure, or can be related to an imageless procedure.

The navigation system <NUM> can operate as an image-based system or as an imageless system. While operating as an imageless system, the navigation system <NUM> can register a subject space (generally defined within and near the subject <NUM>) to a graphical display representing an area of the subject <NUM>, rather than to both the subject space and an image space. Image data of the subject <NUM> need not be acquired at any time, although image data can be acquired to confirm various locations of instruments or anatomical portions of the subject <NUM>. Positions of the subject <NUM> can be tracked and positions of the instrument <NUM> relative to the subject <NUM> can be tracked.

While operating as an imageless system, a position of an anatomical structure can be determined relative to the instrument and the positions of the anatomical structure and the instrument can be tracked. For example, a plane of an acetabulum can be determined by touching several points with the instrument <NUM>. As another example, a position of a femur can be determined in a similar manner. The position of the instrument <NUM> and the anatomical structure can be shown on a display with icons or graphics. The display, however, may not show actual image data captured of the subject <NUM>. Other data can be provided, such as atlas data or morphed atlas data. The atlas data can be image data that is generated or generalized from the subject <NUM>. For example, a brain atlas can be generated based on detail analysis of image data of a brain of a patient. Operation of the navigation system <NUM> as an image based system is further described below.

Although the navigation system <NUM> is described as acquiring image data using an imaging device <NUM>, other data may be acquired and/or used, such as patient and non-patient specific data. The imaging device <NUM> acquires pre-, intra-, or post-operative image data and/or real-time image data of a subject <NUM>. The imaging device <NUM> can be, for example, a fluoroscopic x-ray imaging device that may be configured as a C-arm having an x-ray source <NUM> and an x-ray receiving device <NUM>. Other imaging devices may be included and mounted on the imaging device <NUM>. Calibration and tracking targets and radiation sensors may be included.

The navigation system <NUM> may further include an imaging device controller <NUM>. The imaging device controller <NUM> controls the imaging device <NUM> to (i) capture x-ray images received at the x-ray receiving section <NUM>, and (ii) store the x-ray images. The imaging device controller <NUM> may be separate from the imaging device <NUM> and/or control the rotation of the imaging device <NUM>. For example, the imaging device <NUM> can move in selected directions around the patient <NUM>. Also, the imaging device may include an O-arm ® imaging device as sold by Medtronic, Inc. , having a place of business in Minnesota.

Further, an imager tracking device <NUM> may be included to track a position of selected portions of the imaging device <NUM> to identify the position of the imaging device <NUM> relative to the subject <NUM> while acquiring the image data to assist in registration. The image data can then be forwarded from the imaging device controller <NUM> to a processing module of a navigation computer <NUM> wirelessly or via a link <NUM>. The navigation computer <NUM> can include a processing module that is configured to execute instructions to perform a procedure.

A work station <NUM> can include the navigation computer <NUM>, a navigation display <NUM>, a user interface <NUM>, and an accessible memory system <NUM>. The image data may be transmitted from the controller <NUM> to the work station <NUM> or to a tracking system <NUM>. The workstation <NUM> may be a portable computer, such as a laptop computer or a tablet computer. The navigation computer <NUM> including the computer module may include a general purpose processor that executes instructions for navigating the catheter <NUM> and/or may include an application specific circuit.

The tracking system <NUM>, as discussed further herein, may include a coil array controller (CAC) <NUM> having a navigation device interface (NDI) <NUM>.

While the imaging device <NUM> is shown in <FIG>, any other alternative 2D, 3D or 3D imaging acquired over time to include four dimensions, imaging modality may also be used. For example, any imaging device, such as isocentric fluoroscopy, bi-plane fluoroscopy, ultrasound, computed tomography (CT), multi-slice computed tomography (MSCT), T1 weighted magnetic resonance imaging (MRI), T2 weighted MRI, high frequency ultrasound (HIFU), positron emission tomography (PET), optical coherence tomography (OCT), intra-vascular ultrasound (IVUS), ultrasound, intra-operative, computed tomography (CT), single photo emission computed tomography (SPECT), and/or planar gamma scintigraphy (PGS) imaging devices may be used. Any of these imaging devices may be used to acquire pre- or post-operative and/or real-time images or image data of the subject <NUM>. The images may also be obtained and displayed, generally, in two or three dimensions. In more advanced forms, 3D surface rendering regions are achieved of the subject, which may be rendered or changed in time (fourth dimension). The 3D surface rendering regions may be achieved by incorporating subject data or other data from an atlas or anatomical model map or from pre-operative image data captured by MRI, CT, or echocardiography modalities. Image data sets from hybrid modalities, such as positron emission tomography (PET) combined with CT, or single photon emission computer tomography (SPECT) combined with CT, can also provide functional image data superimposed onto anatomical data to be used to reach target sites within the subject <NUM>.

The navigation system <NUM> further includes the tracking system <NUM>. The tracking system <NUM> includes a localizer <NUM>, which may also be referred to as a transmit coil array (TCA), a tracking array, or a transmit coil assembly. The TCA <NUM> includes coil arrays <NUM> that can transmit or receive. The tracking system <NUM> includes the CAC <NUM>. The localizer <NUM>, the instrument tracking device <NUM> of the stylet <NUM> or the tracking device <NUM>' of the catheter <NUM>. It is understood that the tracked portion may be generally referred to as an instrument and that the tracking device may be generally referred to as an instrument tracking device. The tracking system may also track a dynamic reference frame (DRF) <NUM>. All tracked portions are connected to the CAC <NUM> via the NDI <NUM>. The CAC <NUM> and the NDI <NUM> can be provided in a CAC/NDI container <NUM>. The NDI <NUM> may have communication ports that communicate with the localizer <NUM>, the instrument tracking device <NUM> and/or the DRF <NUM> wirelessly or via wires.

The coil array localizer <NUM> can transmit signals that are received by the DRF <NUM> and at least one tracking device (e.g., the instrument tracking device <NUM>). The tracking device <NUM> can be associated with the instrument <NUM> at a location that is generally positioned within the subject <NUM> during a procedure. The DRF <NUM> can then transmit and/or provide signals, from a DRF tracking device <NUM>, based upon the received/sensed signals of the generated fields from the localizer <NUM> and/or other localizers. It is understood that the tracking system may also be operated in reverse, where the tracking devices <NUM>, <NUM> transmit a field that is sensed by the TCA <NUM>.

The DRF <NUM> can be connected to the NDI <NUM> to forward the information to the CAC <NUM> and/or the navigation computer <NUM>. The DRF <NUM> may be fixed to the subject <NUM> and adjacent to the region where navigation is occurring such that any movement of the subject <NUM> is detected as relative motion between the localizer <NUM> and the DRF <NUM>. The DRF <NUM> can be interconnected with the subject <NUM>. Any relative motion is indicated to the CAC <NUM>, which updates registration correlation and maintains accurate navigation.

In operation, the navigation system <NUM> creates a map between points in image data or an image space, such as one defined by an image <NUM> shown on the display <NUM>, and corresponding points in a subject space (e.g., points in an anatomy of a patient or in a patient space). After the map is created, the image space and subject space are registered to each other. This includes correlating position (location and orientations) in an image space with corresponding positions in a subject space (or real space). Based on the registration, the navigation system <NUM> may illustrate an icon <NUM> (which may include a three-dimensional rendering of the instrument, including the catheter <NUM> and/or the stylet <NUM>) at a navigated position of the instrument <NUM> relative to an image of the subject <NUM> in a super-imposed image. For example, the icon <NUM> can be illustrated relative to a proposed trajectory and/or a determined anatomical target. The work station <NUM> alone and/or in combination with the CAC <NUM> and/or the C-arm controller (or control module) <NUM> can identify the corresponding point on the pre-acquired image or atlas model relative to the tracked instrument <NUM>; and display the position on display <NUM> and relative to the image <NUM>. This identification is known as navigation or localization. The work station <NUM>, the CAC <NUM>, and the C-arm controller <NUM> and/or selected portions thereof can be incorporated into a single system or implemented as a single processor or control module.

To register the subject <NUM> to the image <NUM>, the user <NUM> may use point registration by selecting and storing particular points from the pre-acquired images and then touching the corresponding points on the subject <NUM> with a pointer probe or any appropriate tracked device. The navigation system <NUM> analyzes the relationship between the two sets of points that are selected and computes a match, which allows for a correlation of every point in the image data or image space with its corresponding point on the subject <NUM> or the subject space.

The points that are selected to perform registration or form a map are the fiducial markers, such as anatomical or artificial landmarks. Again, the fiducial markers are identifiable on the images and identifiable and accessible on the subject <NUM>. The fiducial markers can be artificial landmarks that are positioned on the subject <NUM> or anatomical landmarks that can be easily identified in the image data.

The navigation system <NUM> may also perform registration using anatomic surface information or path information (referred to as auto-registration). The navigation system <NUM> may also perform 2D to 3D registration by utilizing the acquired 2D images to register 3D volume images by use of contour algorithms, point algorithms or density comparison algorithms.

In order to maintain registration accuracy, the navigation system <NUM> tracks the position of the subject <NUM> during registration and navigation with the DRF <NUM>. This is because the subject <NUM>, DRF <NUM>, and localizer <NUM> may all move during the procedure. Alternatively the subject <NUM> may be held immobile once the registration has occurred, such as with a head holder. Therefore, if the navigation system <NUM> does not track the position of the subject <NUM> or an area of an anatomy of the subject <NUM>, any subject movement after registration would result in inaccurate navigation within the corresponding image. The DRF <NUM> allows the tracking system <NUM> to track the anatomy and can be used during registration. Because the DRF <NUM> is rigidly fixed to the subject <NUM>, any movement of the anatomy or the localizer <NUM> is detected as the relative motion between the localizer <NUM> and the DRF <NUM>. This relative motion is communicated to the CAC <NUM> and/or the processor <NUM>, via the NDI <NUM>, which updates the registration correlation to thereby maintain accurate navigation.

The tracking system <NUM> can position the localizer <NUM> adjacent to the patient space to generate an EM field (referred to as a navigation field). Because points in the navigation field or patient space is associated with a unique field strength and direction, the tracking system <NUM> can determine the position (which can include location and orientation) of the instrument <NUM> by measuring the field strength and direction or components of the EM field at the tracking device <NUM>. The DRF <NUM> is fixed to the subject <NUM> to identify the location of the subject <NUM> in the navigation field. The tracking system <NUM> continuously determines the relative position of the DRF <NUM> and the instrument <NUM> during localization and relates this spatial information to subject registration data. This enables image guidance of the instrument <NUM> within and/or relative to the subject <NUM>.

To obtain a maximum accuracy it can be selected to fix the DRF <NUM> in each of at least six degrees of freedom. Thus, the DRF <NUM> or any tracking device, such as the tracking device <NUM>, can be fixed relative to axial motion X, translational motion Y, rotational motion Z, yaw, pitch, and roll relative to a portion of the subject <NUM> to which the DRF <NUM> is attached. Any appropriate coordinate system can be used to describe the various degrees of freedom. Fixing the DRF <NUM> relative to the subject <NUM> in this manner can assist in maintaining maximum accuracy of the navigation system <NUM>.

The instrument <NUM> can include the stylet, as discussed above. However, the included discussion may also include the catheter <NUM>, <NUM>', <NUM> as the instrument. Thus, reference to the instrument <NUM> is not intended to limit the instrument that may be tracked and navigated.

Accordingly, the navigation system <NUM> can be used to place the catheter <NUM> with the tracking system <NUM>. As discussed above, this can be performed by acquiring image data of the subject <NUM>, including MRI image data. The MRI image data may be analyzed to determine the location for positioning of the catheter <NUM>, such as in a selected ventricle, including lateral ventricle, first, second, or third ventricles, etc. This position can be identified as an anatomical target to assist in navigation. The navigation system <NUM> may then register the subject space of the subject <NUM> to the image space of the image <NUM> and the location of the catheter <NUM> can be identified as a superimposed icon <NUM> on the image <NUM>. The user <NUM> can then view the display <NUM> while moving the catheter <NUM> into the skull <NUM> and the brain <NUM> of the subject <NUM> to position the catheter <NUM>. The user <NUM> need not, therefore, directly view the catheter <NUM> to determine its position within the subject <NUM>. As discussed above, the catheter <NUM> may include the tracking device <NUM>' directly thereon or the position of the catheter <NUM> may be determined based upon the tracking of the tracking device <NUM> on the stylet <NUM> positioned within the catheter <NUM>. Tracking a stylet, such as the stylet <NUM>, positioned within a lumen or cannula of an instrument may occur according to various embodiments, including those disclosed in <CIT>.

Nevertheless, the user <NUM>, or any appropriate user, can determine positioning of the catheter <NUM> within the subject <NUM> for implanting a shunt system to treat the subject <NUM>, such as treating hydrocephaly. The positioning of the catheter <NUM> within the subject <NUM> can be performed with the navigation system <NUM> to assist in ensuring or confirming that a selected location of the catheter <NUM> is reached during or following implantation. Once implantation of the catheter <NUM> has occurred, the pressure within the lateral ventricle <NUM> can then be monitored using the pressure sensors, such as the pressure sensor <NUM>, discussed above. The monitoring system <NUM>, including the transceiver <NUM>, can then be used to constantly monitor, or at selected times or frequency monitor, the pressure at the catheter <NUM>, including within the lateral ventricle <NUM>. Therefore, the catheter <NUM> can be positioned at a substantially precise location within the brain <NUM> of the subject <NUM> with the navigation system <NUM> and the pressure within the lateral ventricle <NUM> can be consistently monitored with the pressure sensor, such as the pressure sensors <NUM> included with the catheter <NUM>.

Further, it is understood, that the catheter <NUM> need not be implanted with the navigation system <NUM> and can be implanted with any appropriate system according to any appropriate procedure. Further, it is understood that although the exemplary embodiments discussed above refers to catheter <NUM>, that any appropriate catheter or shunt may be implanted and include appropriate pressure sensors, such as those discussed above. Accordingly, the catheter <NUM> is generally directed towards the catheter to be implanted, but may also refer to the catheter <NUM>' and the catheter <NUM>. Moreover, any appropriate pressure sensor, including those discussed above, may be provided with the respective catheters and the catheter <NUM> including only the pressure sensor <NUM>, as discussed above, need not be provided. The pressure sensor discussed in the various exemplary embodiments may include any of the pressure sensors disclosed herein. Further, it is understood that a selected catheter may include a plurality of types of pressure sensors such as the pressure sensor <NUM> and the pressure sensor assembly <NUM>.

With continuing reference to <FIG>, the pressure sensors <NUM>-30b, <NUM>'-30b', according to various embodiments including those discussed above, may be used to provide pressure information to the navigation system <NUM>. As disclosed above, the pressure information may be transmitted to the navigation system <NUM> wirelessly, wired, or in a combination thereof. The pressure information may be used with the navigation system, such as being presented on the display <NUM>. The pressure information may assist the user <NUM> in providing relevant location information and for confirming a location. For example, a pressure measurement may be helpful in determining that the shunt is properly placed in a cerebral ventricle with a high pressure that is to be lowered. The pressure monitoring during navigation can help ensure that flow is occurring through the shunt from the selected implant location, that the shunt is placed away from the cerebrum, etc. Thus, the single from the pressure sensors may assist the user <NUM> in "feeling" the location of the instrument, including the shunt <NUM>, within the subject <NUM>.

Example embodiments are provided so that this disclosure will be thorough.

Claim 1:
A system for monitoring pressure in a subject, comprising:
an elongated instrument (<NUM>, <NUM>', <NUM>) configured to be placed within the subject, having an elongated wall (<NUM>) extending a distance from a first terminal end, being a distal end (<NUM>) to a second terminal end, being a proximal end (<NUM>) and forming a lumen (<NUM>) along at least a portion of the distance, the elongated instrument further including a passage into the lumen through the first terminal end, wherein the elongated wall includes a maximum cross-sectional dimension (15a);
a plurality of portals (<NUM>) formed though the elongated wall along a selected length (<NUM>) configured to allow a fluid to flow into the lumen from an external environment, the selected length being defined from the distal-most of the plurality of portals to the proximal-most of the plurality of portals with respect to the first terminal end;
a pressure sensor (<NUM>, <NUM>) integrated with the elongated instrument, located within the selected length, so as to be configured to measure a pressure within the external environment at the plurality of portals along the selected length and transmit a pressure signal based on the measurement of the pressure, wherein the pressure sensor does not increase the maximum cross-sectional dimension greater than about <NUM>%; and
a monitoring system (<NUM>) configured to receive the pressure signals and provide an output to a user based on the received pressure signals.