Feedback sensing for a mechanical restrictive device

An apparatus comprises an implantable mechanically adjustable band configured to form a restriction in a patient. The band defines an inner diameter. The mechanical adjustability of the band is configured to permit the inner diameter defined by the band to be selectively varied. The apparatus further comprises an adjustment mechanism in communication with the band. The adjustment mechanism is operable to provide the mechanical adjustability of the band. The apparatus further comprises a sensor in communication with one or both of the mechanically adjustable band or the adjustment mechanism. The sensor is configured to sense a physical parameter associated with operation of the band. The physical parameter sensed by the sensor varies with the inner diameter defined by the band. The band may be used as a gastric band, among other potential uses.

BACKGROUND

Many devices and methods for treating obesity have been made and used, including but not limited to adjustable gastric bands. An example of such an adjustable gastric band is disclosed in U.S. Pat. No. 6,067,991, entitled “Mechanical Food Intake Restriction Device,” which issued on May 30, 2000, and which is incorporated herein by reference. Gastric bands may be provided as fluid-based devices or as mechanical devices, among other types, including combinations thereof. Exemplary fluid-based gastric band devices are disclosed in U.S. Pat. No. 4,592,339, entitled “Gastric Banding Device,” which issued on Jun. 3, 1986, and which is incorporated herein by reference. Exemplary mechanical gastric band devices are disclosed in U.S. Pub. No. 2005/0143766, entitled “Telemetrically Controlled Band for Regulating Functioning of a Body Organ or Duct, and Methods of Making, Implantation and Use,” which published on Jun. 30, 2005, and which is incorporated herein by reference. Exemplary mechanical gastric band devices are also disclosed in U.S. Provisional Application Ser. No. 60/530,497, filed Dec. 17, 2003, which is incorporated herein by reference.

Those of ordinary skill in the art will appreciate that it may be advantageous in certain circumstances to sense pressure, strain, or other parameters associated with operation of a gastric band device. For instance, various devices and techniques for pressure data acquisition and processing for fluid-based gastric band systems are disclosed in U.S. Non-Provisional application Ser. No. 11/065,410, filed Feb. 24, 2005, entitled “Device for Non-Invasive Measurement of Fluid Pressure in an Adjustable Restriction Device,” and published as U.S. Pub. No. 2006/0189888; U.S. Non-Provisional application Ser. No. 11/369,531, filed Mar. 7, 2006, entitled “Non-Invasive Pressure Measurement in a Fluid Adjustable Restrictive Device,” and published as U.S. Pub. No. 2006/0211913; and U.S. Non-Provisional application Ser. No. 11/398,940, filed Apr. 6, 2006, entitled “Monitoring of a Food Intake Restriction Device,” and published as U.S. Pub. No. 2006/0199997. The disclosure of each of those applications and publications is incorporated by reference herein. Such parameter data may be obtained before, during, and/or after adjustment of a gastric band, and may be useful for adjustment, diagnostic, monitoring, or other purposes, and may be obtained with respect to a mechanical gastric band. The foregoing examples are merely illustrative and not exhaustive. While a variety of techniques and devices have been used treat obesity, it is believed that no one prior to the inventors has previously made or used an invention as described in the appended claims.

Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings.

DETAILED DESCRIPTION

Referring toFIG. 1, an exemplary adjustable gastric band10forms an adjustable stoma between upper portion12and lower portion14of a patient's stomach16. Of course, band10may be positioned at a variety of alternative locations, including but not limited to at or near the gastro-esophageal junction of the patient. In the present example, band10is kept in place by attaching its two ends together and extending portion18of stomach16over the adjustable gastric band10by suturing portion18to stomach16. The stoma may be adjusted by varying the effective inner perimeter (which may also referred to as inner diameter, although the shape is not necessarily a circle) of band10. An actuator is associated with band10to vary the inner perimeter. The actuating device may be integral with the band10itself or be external thereto.

FIGS. 2-5illustrate an exemplary adjustable band148that includes actuators150and152. Since actuators150and152are identical to each other in this particular example, only actuator150will be discussed. Of course, actuators150and152need not be identical, and may have any suitable number or types of differences. In the present example, actuator150is actuated by an increase of pressure within its internal cavity. But instead of relying on an external source of fluid pressure, actuator150is filled with a two phase medium, such as a propellant. For example, Vertrel CF may be used. Thus, an injection port and a bidirectional infuser are unnecessary. Alternatively, an injection port, infuser, or other device may be incorporated if desired.

In order to effect the phase change and expansion of the propellant, thermal element154(156for actuator152) is disposed adjacent actuator150. In the embodiment depicted, thermal element154is a thin film Kapton heater which is attached to a surface of actuator150. Wires (not shown) extend from element154, to a controller (not shown) for selectively applying an electrical signal to element154. In the embodiment depicted, when energized, element154produces sufficient heat to warm the two phase medium within the internal cavity of actuator150, causing the medium to begin changing phase from liquid to gas, thereby increasing the pressure within actuator150. Actuator150is configured to change shape in response to this increase in internal pressure, with the change in shape adapted to vary the size of the stoma.

In the embodiment depicted, actuator150lengthens in response to an increase in pressure. A control may measure the change in capacitance of actuator150to determine its length. The self capacitance of actuator150may vary as it lengthens. Capacitance change may be detected by incorporating actuator150into an LC circuit, and the frequency variations of an AC signal in the circuit may be compared to a reference frequency to detect the amount of expansion. Other processing may be used in addition or in the alternative. Additionally, a self contained actuator, such as actuator150, may be used in conjunction with any suitable band configuration, such as any other band described herein. In addition, any other type of actuator may be used in lieu of actuator150, including but not limited to the various other types of actuators explicitly described herein relative to other gastric band embodiments. Accordingly, the term “actuator” should in no way be read as limited to actuator150as described herein with reference toFIGS. 2-5or as shown inFIGS. 2-5.

The embodiment of band148depicted inFIGS. 2-5includes a clutch mechanism configured to hold band148at a particular size unless acted upon by either actuator150or152. Although any suitable clutch mechanism may be used,FIGS. 9-12depict pawl160which engages ratchet member162. Pawl160is rotatably supported about transverse pivot164, which separates pawl into upper portion166and lower portion168. Lower portion168terminates in an angle170which is shaped complementarily to engage notches172of ratchet member162. First ends150aand152aof actuators150and152are attached to respective sides of upper portion166in any suitable manner. Alternatively, actuators150and152could be configured as a single member with two separate internal cavities, with pawl160being molded to the portion between the two internal cavities.

First ends of resilient members, depicted in the figures as springs174and176, are attached to pawl160adjacent distal end160a. Second ends of springs174and176are secured to shroud178, which comprises first portion148aof band148, and which covers and contains actuators150and152. Springs174and176maintain pawl160generally perpendicular to ratchet162, which is carried by second portion148b. Relative longitudinal movement between first portion148aand second portion148beffects the change in the size of opening180, as can been seen inFIGS. 2 and 4. Springs174and176provide a counterbalanced load at distal end160aof pawl160which, in the absence of a force exerted by extension of either actuator150or152due to actuation, is sufficient to maintain angle170engaged in one of notches172to prevent relative movement between first portion148aand second portion148b, maintaining the selected size of area180.

To adjust the size of area180, and thusly the stoma size, either actuator150or152is actuated. In the embodiment depicted, to reduce the size of area180, actuator150is actuated, as seen inFIG. 4. As seen inFIGS. 4 and 5, when actuator150is actuated, shroud178restrains outward movement of actuator150, resulting in end150aurging against upper portion166, rotating pawl160counter clockwise and disengaging angle170from notches172. Stops182prevent excessive rotation of pawl160in either direction, while allowing sufficient rotation for pawl160to disengage ratchet162. As actuator150extends in length, and pawl160disengages ratchet162, first and second portions148aand148bmay move relative to each other.

Second end150bof actuator150is connected to distal end148b′ of second portion148b. Upon disengagement of pawl162, actuator150urges distal end148b′ clockwise inFIG. 5and first portion148a, via the force exerted on pawl160through pivot164to shroud178, counterclockwise, increasing the amount of overlap between first portion148aand second portion148b, reducing the size of area180. When the desired size of area180is reached, element154is deactivated, and when the pressure of the medium within actuator150drops sufficiently, pawl160reengages ratchet162, thereby maintaining the desired size of area180.

In positions where one actuator is compressed and the other actuator is extended, such as seen inFIG. 4, springs174and176are sufficient to overcome any moment on pawl160created by unactuated actuators150and152, and maintain pawl160in engagement with ratchet162.

Self contained actuators150and152are not limited to use with the configuration of band148, nor is band148limited to use with self contained actuators. Suitable variations will be apparent to those of ordinary skill in the art.

Adjustable band148of the present example further comprises a pressure sensing strip300. Pressure sensing strip300comprises a flexible substrate302having a plurality of pressure sensing elements304disposed therein or thereon. Pressure sensing strip300is secured to first portion148a, such as by an adhesive or by any other suitable means. Each of the pressure sensing elements304is operable to sense pressure, such as by converting a physical deflection into an electrical signal, and thereby provide pressure data. Pressure sensing elements304may comprise any suitable type(s) of pressure sensors, including but not limited to piezoresistive, capacitive, strain gauges, or any other suitable sensor type, including combinations thereof. Each of the pressure sensing elements304is in communication with a wire or other type of communication conduit, which is operable to transmit data indicative of pressure sensed by pressure sensing elements304. While ten pressure sensing elements304are shown inFIGS. 2 and 4, it will be appreciated that any suitable number of pressure sensing elements304may be used in any suitable arrangement. For instance, pressure sensing elements304may be arranged in a generally straight line or arrayed in some other pattern.

In the present example, pressure sensing strip300is configured to fit between a gastric band148and a patient's stomach16. Pressure sensing strip300may thus be used to sense pressure at the tissue interface of the stomach16and gastric band148. Pressure sensing strip300may be used to determine an average pressure at such interface and/or may be used to obtain a plurality of discrete pressure measurements at multiple points around such interface. Pressure sensing strip300may be oriented such that pressure sensing elements304face stomach16or gastric band148. Alternatively, pressure sensing elements304may be provided on both sides of pressure sensing strip300. In yet another embodiment, a plurality of pressure sensing elements304are integrated directly into first portion148a. For instance, pressure sensing elements304may comprise a MEMS pressure or stress sensor array from Lawrence Livermore National Laboratory. Other suitable types of pressure sensing elements304and locations for pressure sensing elements304will be apparent to those of ordinary skill in the art.

In view of the foregoing, it will be appreciated that pressure sensing elements304may be used to obtain discrete pressure measurements around tissue adjacent to such pressure sensing elements304. Pressure sensing elements304may be configured such that each pressure measurement may be associated with a particular pressure sensing element304, which may permit association of pressure measurements with particular tissue locations. For instance, being able to associate pressure measurements with particular tissue locations may permit a user to determine whether there is too much or too little pressure against a particular tissue location. Similarly, discrete pressure measurements may be used to identify points of tissue erosion, to detect migration of gastric band38, or for other purposes.

Furthermore, to the extent that discrete pressure measurements may be obtained using a plurality of pressure sensing elements304, a pressure profile may be generated. For instance, a pressure profile may correlate a given pressure measurement with a particular sensor, and therefore with a particular location on a gastric band148and/or stomach16. Similarly, a pressure profile may be used to establish how pressure is allocated along the length or circumference of the interface of a gastric band148and stomach16. It will also be appreciated that discrete pressure measurements and/or a pressure profile may be geometrically reconstructed to show the relative shape and/or size of food being swallowed by a patient, or for other purposes. Other ways in which a pressure profile may be established and/or used will be apparent to those of ordinary skill in the art.

Suitable structures or techniques for correlating a pressure measurement with a particular pressure sensing element304will be apparent to those of ordinary skill in the art. In one embodiment, each pressure sensing element304has an associated identification code, which may be transmitted with pressure data obtained with the corresponding pressure sensing element304. Alternatively, each pressure sensing element304may be associated with a dedicated data interface port (not shown), and each such port may transmit or otherwise be associated with a unique identification code. In another variation, as discussed in greater detail below, each pressure sensing element304may be configured to provide a unique reflected signal or signature that distinguishes each sensing element304from other sensing elements304.

As another variation, pressure measurements may be averaged, compared, or otherwise combined by a local component (e.g., an ASIC, etc.) on a pressure sensing strip300, such that a pressure value communicated externally is not associated with a particular pressure sensing element304. Of course, some other component (e.g., an external component, etc.) may also average, compare, or otherwise combine pressure measurements. Other ways in which discrete or averaged pressure measurements may be obtained, communicated, handled, and used will be apparent to those of ordinary skill in the art.

In one embodiment, pressure data is communicated from pressure sensing elements304via a wire (not shown) to a transmitter (not shown). The transmitter is operable to further communicate the pressure data wirelessly to a receiver external to the patient. For instance, the transmitter may comprise one or more RF coils operable to provide telemetry with receiver coils located external to the patient. Similarly, to the extent that pressure sensing elements304require power from an external source for operation, the RF coils used to provide telemetry may also be used to provide transcutaneous energy transfer (TET). Alternatively, a dedicated set of TET coils may be provided. In another embodiment, a battery or other internal power source is provided in the transmitter, pressure sensing strip300, or elsewhere. In any event, a transmitter, TET coils, a battery, and/or any other component in communication with a wire may be positioned in any suitable location.

In yet another embodiment, a coil (not shown) is provided within pressure sensing strip300. Each pressure sensing element304is in communication with the coil. As with the telemetry and TET coils discussed above, the coil may be operable to provide both telemetry and TET with an external device. Alternatively, separate coils within pressure sensing strip300may be used—one for telemetry and one for TET. In yet another embodiment, one or more coils are provided within pressure sensing strip300while one or more other coils are provided elsewhere. In yet another embodiment, each pressure sensing element304has a respective discrete coil (not shown) that is operable to provide telemetry and/or TET.

It will be appreciated that pressure sensing elements304may be un-powered or passive. For instance, a pressure sensing element304may be configured to reflect a signal transmitted from an external transmitter such as a telemetry coil. The reflected signal may then be read and demodulated or decoded by the transmitter device or by some other receiver. The reflected signal may indicate a parameter (e.g., pressure, etc.) sensed by a sensor. By way of example only, each pressure sensing element304may comprise a sensor such as any of the sensors described in U.S. Pat. No. 6,855,115, issued Feb. 15, 2005, and entitled “Implantable Wireless Sensor for Pressure Measurement within the Heart;” U.S. Pub. No. 2003/0136417, published Jul. 24, 2003, and entitled “Implantable Wireless Sensor;” and/or WO 03/061504, published Jul. 31, 2003, and entitled “Implantable Wireless Sensor.” The disclosure of each of U.S. Pat. No. 6,855,115; U.S. Pub. No. 2003/0136417; and WO 03/061504 is incorporated by reference herein. Of course, any of the transmitters or receivers described in those references may also be used. Furthermore, any sensor or sensing element described herein may be provided as an un-powered or passive element. It will also be appreciated that each sensor may be configured to provide a unique reflected signal or signature that distinguishes each sensor from other sensors. Such unique signals or signatures may permit a pressure profile to be generated. Other ways of providing a wireless, passive, and/or reflective sensor will be apparent to those of ordinary skill in the art.

In still another embodiment, one or more of pressure sensing elements304are in communication with an implanted controller (not shown), which also selectively applies electrical signals to element154and element156as described above. In this embodiment, signals indicative of pressure from pressure sensing elements304are processed by the controller to influence the electrical signals applied to element154and element156by the controller. For instance, the controller may be preprogrammed with a maximum or ideal pressure level, and the controller may apply electrical signals to element154and element156while receiving feedback pressure signals from pressure sensing elements304until the maximum or ideal pressure level is reached. The controller may then cease applying electrical signals to element154and element156. Of course, signals from pressure sensing elements304may be used as feedback or otherwise in any other suitable way.

Still other variations of pressure sensing strip300will be apparent to those of ordinary skill in the art. By way of example only, pressure sensing strip300may be substituted by, supplemented with, or varied in accordance with any of the pressure sensing devices disclosed in U.S. Non-Provisional application Ser. No. 11/682,459, filed Mar. 6, 2007, entitled “Pressure Sensors for Gastric Band and Adjacent Tissue,” the disclosure of which is incorporated by reference herein. Similarly, any gastric band described herein or in any of the applications/publications that have been incorporated by reference herein may be modified with any suitable version of pressure sensing strip300or pressure sensing elements304without pressure sensing strip300.

FIG. 6illustrates another embodiment of an actuator, in conjunction with another embodiment of an adjustable band184. Band184includes first portion184aand second portion184b, with each portion having attachment mechanism186which may be used to connect ends184a′ and184b′ together after band184has been disposed about an anatomical feature. Although attachment mechanism186is depicted as having a transverse dove tail configuration, any attachment mechanism may be used. Second portion184bincludes a shroud188which encloses end184a″ throughout its travel, as described below.

Band184is comprised of any suitable biocompatible material having sufficient resilience, strength, and fatigue resistance, such as implant grade silicone. Of course, any other material(s) having any suitable properties may be used. The inner surface may be of any suitable configuration which does irritate or damage adjacent tissue, such as for example, as shown in U.S. Provisional Patent Application Ser. No. 60/530,497, filed Dec. 17, 2003, for Mechanically Adjustable Gastric Band, which is incorporated by reference. Second portion184bmay have a balloon190disposed on its inner surface, which is depicted as extending past attachment mechanism186. Balloon190may have a fixed volume. It is noted that, in the embodiment depicted, the inner surface of first portion184adoes not have a similar feature, though it may in alternative embodiments. As illustrated inFIG. 6, band184is at its largest size, encircling area192, having a diameter of approximately 1.35 inches (34.29 mm), for example only. At its smallest size, when end184a″ has traveled its full distance within shroud188, most of first portion184ais disposed within shroud188, the ends of balloon190are proximal each other and area192has a diameter of about 0.71 inches (18 mm) by way of example only. (It is noted that although area192is depicted as generally circular and is referred to as having a diameter, area192is not limited to a circle or circular shape.) Thus, in the embodiment depicted, first portion184ais small enough to move through opening194, and the inner surface of first portion184adoes not have any features, such as a balloon, which would interfere with such movement. Of course, these components may be arranged and configured in a number of alternative ways.

Actuator196is depicted as comprising generally cylindrical bellows198, which is illustrated as a corrugated member having a series of folds creating spaced apart circular ridges. Although the ridges and folds are illustrated as being parallel, and evenly shaped and spaced, they are not required to be. Bellows198may be made from any suitable biocompatible material, such as titanium which is MRI safe. Bellows198is closed at end200, defining internal cavity202. Internal cavity202may be in fluid communication with a source of fluid, which may be a remotely operated bidirectional infuser204, similar to infuser64, or any other fluid source capable of repetitively bidirectionally moving fluid. In the embodiment depicted, end206of bellows198is secured to housing208of bidirectional infuser204, placing internal cavity202in fluid communication with variable internal volume210. In the embodiment depicted, the fluid within internal cavity202and internal volume210may be saline solution or any other fluid. Movement of bellows198is constrained to be longitudinal by bellows housing212, which is secured to housing208.

Drive cable assembly214is provided between bellows housing212and band184. Cable drive assembly214includes fitting216, which is secured to bellows housing212, and fitting218, which is secured to end184b″, each being secured in any suitable manner. Sheath220extends between fittings216and218, providing a mechanical ground for cable222disposed therein. Cable end224is secured to end184a″, and cable end226is secured to bellows end200, each being secured in any suitable manner.

To actuate actuator196, fluid from internal volume210is forced through fluid port228, lengthening bellows198. As a result of the relative cross sectional areas of bellows198and internal volume210, bellows198acts as an amplifier, with a small amount of fluid producing the longitudinal expansion required to adjust the size of band184. As end200moves within bellows housing212, cable end224moves band end184a″ within shroud188relative to portion184b, thereby decreasing the size of the stoma created by band184. To increase the size of the stoma, fluid is withdrawn from bellows198, retracting cable222, moving end184a″ toward end184b″.

Cable assembly214may be made of any suitable biocompatible material. Cable end224of this example is sufficiently stiff to push end184a″ within shroud188the desired distance. Shroud188protects surrounding tissue from the movement of end184a″, and also constrains the movement of cable end224and cable222, functioning similarly to sheath220, to produce the desired movement of end184a″.

In the present example depicted inFIG. 6, a force sensor400is engaged with cable222. Force sensor400is operable to sense force exerted on or by cable222. Force sensor400may comprise any suitable type of force sensor, including but not limited to a mechanical, hydraulic, strain gauge, piezoresistive, or piezoelectric type of force sensor. By way of example only, one side of force sensor400may be coupled with bellows end200and/or a segment of cable222, with the other side of force sensor400being coupled with another segment of cable222. In other words, cable222may be provided in two segments, with a first segment being provided on one side of force sensor400and second segment being provided on the other side of force sensor400. Coupling of force sensor400with cable222or any other component may be provided by a linkage or any other suitable structure or technique. Other suitable configurations and techniques for engaging force sensor400with cable222will be apparent to those of ordinary skill in the art. Similarly, other suitable locations for force sensor400will be apparent to those of ordinary skill in the art. It will also be appreciated that force sensor400may comprise a diaphragm, a strain element, a resilient member, or any other suitable component(s) configured to sense force.

Force sensed by force sensor400may be indicative of or correlated with pressure exerted by gastric band184on a patient's stomach16. In addition, similar to pressure sensing elements304discussed above, force sensor400may communicate a signal indicative of force to an implanted controller (e.g., via wire), to a receiver located external to the patient (e.g., via RF telemetry), and/or to any other suitable location. Signals indicative of force from force sensor400may also be used in a manner similar to those described above with respect to signals indicative of pressure from pressure sensors304. It will also be appreciated that any gastric band described herein or in any of the applications/publications that have been incorporated by reference herein may be modified with any suitable version of force sensor400.

FIGS. 7-9illustrate alternate embodiments of bidirectional infusers showing alternate configurations of a bellows.FIG. 7illustrates bellows230disposed within bellows housing232having arcuate portion234. Bellows housing232may include straight section236as shown. The arcuate configuration allows the length of bellows housing232to be longer than the distance from center238while not extending very far beyond the circumference of bidirectional infuser240, increasing the available stroke of bellows230. Bellows housing232may be secured to infuser240in any suitable manner, or may be formed integrally therewith.FIG. 8illustrates bidirectional infuser242with septum244offset from the center of outer periphery of infuser242. This allows the portion of bellows housing246overlying infuser242to be longer in comparison to bidirectional infuser204which has a centrally disposed septum.FIG. 9illustrates injection port248with bellows250. To actuate bellows250, fluid is injected or withdrawn via septum252. It will be appreciated that any of these infusers/ports may be used with any type of band. In other words, any component described herein may be combined or interchanged with any other component described herein, as desired. It will also be appreciated that, in these configurations (among others), a pressure sensor may be incorporated in the fluid path (e.g., within internal volume210, etc.) to sense a change in fluid pressure when fluid is added, removed or compressed. This may provide a secondary feedback of the adjusted stroke of an actuator196, which may be translated to the diameter change in an associated gastric band184.

FIGS. 10-11depict yet another exemplary gastric band60. Versions of gastric band60, as well as other implantable restriction devices, are disclosed in European Patent Application Publication EP1547549A2, published Jun. 29, 2005, entitled “Mechanically Adjustable Gastric Band,” the disclosure of which is incorporated by reference herein. Gastric band60of the present example comprises a band62that has a first end66and a second end68and forms an enclosure58to restrict food intake through the stomach of a patient. Band62is made of a spring-like, non-magnetic (for MRI compatibility) material and is in a straight configuration when in a unconstrained mode. A cushion64is made of a soft, biocompatible material such as silicone and attaches to the inside of band62to interface with the stomach tissue. Other suitable materials and configurations for band62and cushion64will be apparent to those of ordinary skill in the art.

First end66of band62attaches to a band actuator72. Second end68of band62inserts into band actuator72after the surgeon has placed band62around the stomach. Band actuator72comprises a motor78, which drives a pinion74through a transmission76. Electrical conductors80electrically connect motor78to an implantable control port110, which is shown inFIGS. 12-13, having a control unit118. Pinion74operationally engages a plurality of slots70of band62. When motor78rotates in a first direction, enclosure58reduces in diameter; when motor78rotates in an opposite second direction, enclosure58increases in diameter. The surgeon may therefore control the amount of restriction to food intake through the stomach.

FIGS. 10-11also show a release mechanism94inside of band actuator72. Release mechanism94comprises a lever84having an axle86, a first end88, and a second end90. When in an engaging mode, first end88bears against band62, thus maintaining operational engagement of band62with pinion74. When in a releasing mode, first end88is swung away about axle86from band62, thus allowing band62to be disengaged from pinion74. Release mechanism94further comprises a piston98that attaches via a link92to second end90of lever84. A spring100normally urges piston98to move in a direction that causes lever84to be in the engaging mode. A chamber96containing piston98fluidly attaches to a tube104via a fitting102. Tube104fluidly connects to a reservoir116formed within a housing112of implantable control port110, shown inFIGS. 12-13. Implantable control port110further includes a septum114made of silicone and which is needle penetrable so that a surgeon may inject a fluid into reservoir116and actuate piston98of release mechanism94. Implantable control port110may be implanted subcutaneously in a patient to be within the transcutaneous energy transmission range, and to allow the surgeon to access septum114to inject a fluid into reservoir116. Release mechanism94allows non-surgical release of the constriction of band62on the stomach in the event of electromechanical failure.

Release mechanism94is not limited to hydraulic actuation as described above, but may instead incorporate a pneumatic, electrical, or any other type of actuation. Implantable control port110may therefore be modified to omit septum114, reservoir116, and tube104. Furthermore, control unit118may be integrated into gastric band60or otherwise provided. It will also be appreciated that release mechanism94or modified versions thereof may be used with gastric bands that are actuated with devices other than electric motors. For example, release mechanism94may be used with a gastric band that is inflatable with a fluid such as saline. In other embodiments, release mechanism94is omitted altogether. Still other variations of gastric band60and its components will be apparent to those of ordinary skill in the art.

In the present example, a plurality of proximity sensors500are provided within cushion64. Each proximity sensor500comprises a coil, and proximity sensors500are associated with a resonant RF frequency. Of course, any other type of proximity sensor500may be used. Each proximity sensor500of the present example is in communication with a coil interface circuit504via a respective wire502. Coil interface circuit504is configured to sense inductance and/or capacitance change relative to proximity sensors500. In particular, as band62is pulled by pinion74, thereby effectively shrinking the inner diameter defined by cushion64, proximity sensors500are drawn closer together. Such relative movement of proximity sensors500causes a change in the resonant frequency associated with the proximity sensors500, as the resonant frequency changes with respect to the capacitance and/or inductance change occurring when proximity sensors500are moved relative one another. The change in the inner diameter defined by cushion64may therefore be determined by the change in resonant frequency, capacitance, and/or inductance encountered upon corresponding movement of proximity sensors500. Coil interface circuit504may therefore sense the proximity of proximity sensors500relative one another. Alternatively, proximity sensors500and coil interface circuit504may operate under any other suitable principles.

The change in resonant frequency, capacitance, and/or inductance encountered upon movement of proximity sensors500may be communicated to any other component in any suitable fashion. For instance, a signal indicative of resonant frequency, capacitance, and/or inductance change may be communicated by coil interface circuit504to control unit118to influence the rotation of pinion74by motor78. In particular, signals from coil interface circuit504may be used as feedback to prevent overtightening of gastric band60. Alternatively, signals from coil interface circuit504may be communicated to a device (not shown) that is located external to the patient. Coil interface circuit504may also receive power from any suitable internal (e.g. a battery) or external power source (e.g., via TET). Accordingly, it will be appreciated that proximity sensors500and coil interface circuit504may be used in any manner similar to those described above with respect to pressure sensing elements304and force sensor400. Other variations will be apparent to those of ordinary skill in the art. It will also be appreciated that any gastric band described herein or in any of the applications/publications that have been incorporated by reference herein may be modified with any suitable version of proximity sensors500.

As is also shown inFIG. 10, a gastric band60may comprise a linear displacement sensor510. In the present example, linear displacement sensor510comprises a linear voltage displacement transducer, though any other type of linear displacement sensor may be used. While shown on a band60that has proximity sensors500, it will be appreciated that linear displacement sensor510may be provided on any other band, including but not limited to a band that lacks any other type of sensor. In this example, linear displacement sensor510is engaged with band62. Other suitable locations for linear displacement sensor510will be apparent to those of ordinary skill in the art.

Linear displacement sensor510of the present example is able to determine linear displacement of band62relative to the housing of band actuator72by sensing the linear displacement of linear displacement sensor510relative to a reference position. For instance, the position of linear displacement sensor510may be established or “zeroed out” prior to an adjustment of band62, and as band62is tightened, linear displacement sensor510may sense its displacement from such a reference position. In another embodiment, linear displacement sensor510comprises an arm or other component (not shown) that is secured to the housing of band actuator72. Such an arm or other component may move within the linear displacement sensor510, and the displacement of the arm or other component within linear displacement sensor510may constitute the displacement sensed by linear displacement sensor510. Alternatively, any other components or principles of operation for a linear displacement sensor510may be incorporated.

It will be appreciated that the linear displacement sensed by linear displacement sensor510of the present example may be indicative of or correlated with the effective inner diameter defined by cushion64. Linear displacement sensor510may communicate signals indicative of linear displacement in any suitable fashion. For instance, linear displacement sensor510may communicate linear displacement signals to control unit118to influence the rotation of pinion74by motor78. Alternatively, signals from linear displacement sensor510may be communicated to a device (not shown) that is located external to the patient. Accordingly, it will be appreciated that linear displacement sensor510may be used in any manner similar to those described above with respect to pressure sensing elements304, force sensor400, and/or proximity sensors500. Other variations will be apparent to those of ordinary skill in the art. It will also be appreciated that any gastric band described herein or in any of the applications/publications that have been incorporated by reference herein may be modified with any suitable version of linear displacement sensor510.

In another embodiment the current supplied by motor78is sensed via electrical conductors80and control unit118. As with other sensed parameters described herein, the sensed current may be processed by a device that is external to the patient or may be processed by a device that is within the patient (e.g., within control unit118). In any case, the amount of current supplied by motor78may be indicative of torque provided by motor78, such that sensed current may be translated into sensed torque. It will be appreciated that some assumptions may need to be made in order to correlate current with torque, such as an assumption that the voltage is fixed. It will also be appreciated that torque may be sensed using a torque sensor (not shown) or using any other suitable device or processing.

Regardless of how obtained, sensed torque may be provided in a feedback loop to regulate control of motor78, to an external device for monitoring purposes, or to any other component or device for any other purpose. Accordingly, it will be appreciated sensed torque may be used in any manner similar to sensed parameters described above with respect to pressure sensing elements304, force sensor400, proximity sensors500, and/or linear displacement sensor510. Other variations will be apparent to those of ordinary skill in the art. It will also be appreciated that any gastric band described herein or in any of the applications/publications that have been incorporated by reference herein may be modified with any suitable implementation of torque sensing.

FIG. 14shows another exemplary gastric band600. In this embodiment, gastric band600comprises a flexible yet non-tensile band602and a tensile bladder604secured to band602. A rigid strap607is secured to the outer side of bladder604. By way of example only, band602may comprise a metal, plastic, textile, or any other material(s), including combinations thereof. Bladder604may comprise silicon or any other suitable material(s), including combinations thereof. Strap607may comprise a metal, plastic, or any other suitable material(s), including combinations thereof. Band602, bladder604, and strap607may have any suitable alternative properties.

One end of band602is fixedly secured to a latch606, while the other end of band602is passed through latch606and may be adjusted relative to latch606to obtain a desired inner diameter defined by band602. Latch606is configured such that, when band602is adjusted to provide a desired inner diameter, latch606may be manipulated to secure the position of band602relative to latch606. Suitable mechanisms or features for providing such securing by latch606will be apparent to those of ordinary skill in the art. Similarly, suitable mechanisms or features for adjusting the position of the free end of band602relative to latch606will be apparent to those of ordinary skill in the art. By way of example only, the adjustment of band602relative to latch606may be provided mechanically, hydraulically, by hand, or otherwise.

Each end of bladder604is secured to latch606. Similarly, each end of strap607is secured relative to latch606. By way of example only, one end of bladder604may be permanently secured to latch606, while the other end of bladder604may comprise a feature (not shown) that is selectively engageable with latch606. For instance, such a feature may be used to secure a free end of bladder604to latch606when gastric band600is initially secured to a patient's stomach16. Bladder604defines a vessel605holding a fluid (e.g., saline, etc.) and a pressure sensor608. Pressure sensor608is operable to sense the pressure of the fluid within vessel605. Pressure sensor608may be configured to communicate pressure data in a manner similar to communication of data by any other type sensor described herein. For instance, pressure sensor608may communicate pressure data to an external device using direct telemetry, using telemetry via an implanted data relay located elsewhere within the patient, or using any other suitable technique. In addition or in the alternative, pressure sensor608may communicate data to another implanted device, which may then process the pressure data for any suitable purpose.

FIG. 14shows band602in an extended configuration, providing a relatively large inner diameter. While a substantial portion of bladder604is secured to band602, such as by an adhesive, etc., a portion of bladder604near latch606is not secured to band602, providing a disconnect610between band602and bladder604in the configuration shown inFIG. 14. As shown inFIG. 15, band602is pulled further through latch606for adjustment to provide a smaller inner diameter, such as to form a restriction in a patient's stomach16. Disconnect610permits band602to be pulled further through latch606without bladder604being pulled through or into latch606.

As is also shown inFIG. 15, the engagement of bladder604with band602will cause bladder604to stretch or otherwise provide a greater vessel605volume when band602is pulled further through latch606. It will be appreciated that, since a fixed amount of fluid is provided in vessel605, this increase in vessel605volume will cause a decrease in the pressure of fluid within vessel605. Accordingly, the pressure of fluid within vessel605will decrease as the inner diameter defined by band602decreases. Similarly, if the inner diameter defined by band602is increased (e.g., by pushing band602back through latch606), the volume of vessel605will decrease, causing an increase in the pressure of fluid within vessel605. Such changes in pressure may be detected by pressure sensor608and communicated as described above. Other variations of gastric band600, including variations of its components, uses, and principles of operation, will be apparent to those of ordinary skill in the art.

FIG. 16shows another exemplary gastric band700. In this embodiment, gastric band700comprises a flexible yet non-tensile band702and a flexible yet non-tensile bladder704secured to band702. Suitable materials for band702and bladder704will be apparent to those of ordinary skill in the art, as will suitable alternative properties of band702and bladder704. In the present example, one end of band702is fixedly secured to a latch706, while the other end of band702is passed through latch706and may be adjusted relative to latch706to obtain a desired inner diameter defined by band702. Latch706is configured such that, when band702is adjusted to provide a desired inner diameter, latch706may be manipulated to secure the position of band702relative to latch706. Suitable mechanisms or features for providing such securing by latch706will be apparent to those of ordinary skill in the art. Similarly, suitable mechanisms or features for adjusting the position of the free end of band702relative to latch706will be apparent to those of ordinary skill in the art.

Bladder704is secured to band702, such as by an adhesive or other suitable means. In addition, an end of bladder704is secured to latch. Bladder704defines a vessel705holding a fluid (e.g., saline, etc.) and a pressure sensor708. Pressure sensor708is operable to sense the pressure of the fluid within vessel705. Pressure sensor708may be configured to communicate pressure data in a manner similar to communication of data by any other type sensor described herein. For instance, pressure sensor708may communicate pressure data to an external device using direct telemetry, using telemetry via an implanted data relay, or using any other suitable technique. In addition or in the alternative, pressure sensor708may communicate data to another implanted device, which may then process the pressure data for any suitable purpose.

FIG. 16shows band702in an extended configuration, providing a relatively large inner diameter. Latch706of this example comprises a tapered feature710. As band702and bladder704are pulled further through latch706to provide a smaller inner diameter, such as to form a restriction in a patient's stomach16, taper feature710is configured to squeeze bladder704. In particular, band702, bladder704, and taper feature710are configured such that fluid in vessel705is forced out of whatever portion of vessel705passes taper feature710as band702and bladder704are pulled further through latch706. In other words, the volume of vessel705will decrease as band702and bladder704are pulled further through latch706. With a fixed amount of fluid being within vessel705, it will be appreciated that a decrease in vessel705volume will cause an increase in the pressure of the fluid within vessel705.

Accordingly, the pressure of fluid within vessel705will increase as the inner diameter defined by band702decreases. Similarly, if the inner diameter defined by band702is increased (e.g., by pushing band702back through latch706), the volume of vessel705will increase, causing a decrease in the pressure of fluid within vessel705. Such changes in pressure may be detected by pressure sensor708and communicated as described above. Other variations of band700, including variations of its components, uses, and principles of operation, will be apparent to those of ordinary skill in the art.

FIGS. 17-18show yet another embodiment of a gastric band800. In this embodiment, gastric band800comprises a bladder802, a band804, and a latch mechanism806. Bladder802and band804are secured adjacent one another, such as by an adhesive. Bladder802and band804may each be formed of silicon or any other suitable material(s), including combinations thereof. One end of bladder802is fixedly secured to a latch mechanism806, while the other end of bladder802is passed through latch mechanism806and may be adjusted relative to latch mechanism806to obtain a desired inner diameter defined by band802. Similarly, one end of band804is fixedly secured to a latch mechanism806, while the other end of band804is passed through latch mechanism806and may be adjusted relative to latch mechanism806. Latch mechanism806is configured such that, when bladder802and band804are adjusted to provide a desired inner diameter, latch mechanism806is operable to secure the position of bladder802and band804relative to latch mechanism806. Suitable mechanisms or features for providing such securing by latch mechanism806will be apparent to those of ordinary skill in the art. Similarly, suitable mechanisms or features for adjusting the position of the free end of bladder802and band804relative to latch mechanism806will be apparent to those of ordinary skill in the art.

Bladder802defines a vessel803holding a fluid (e.g., saline, etc.) and a pressure sensor808. While pressure sensor808is shown as being located at an end of vessel803, it will be appreciated that pressure sensor808may positioned in any other suitable location within vessel803or elsewhere. In the present example, pressure sensor808is operable to sense the pressure of the fluid within vessel803. Pressure sensor808may be configured to communicate pressure data in a manner similar to communication of data by any other type sensor described herein. For instance, pressure sensor808may communicate pressure data to an external device using direct telemetry, using telemetry via an implanted data relay, or using any other suitable technique. In addition or in the alternative, pressure sensor808may communicate data to another implanted device, which may then process the pressure data for any suitable purpose.

FIG. 17shows bladder802and band804in an extended configuration, providing a relatively large inner diameter. Latch mechanism806of this example comprises a pair of rollers810. Bladder802and band804pass between rollers810such that rollers810squeeze bladder802. In particular, bladder802, band804, and rollers810are configured such that fluid in vessel803is forced out of whatever portion of vessel803passes rollers810as bladder802and band804are pulled further through latch mechanism806. In other words, the volume of vessel803will decrease as bladder802and band804are pulled further through latch mechanism806. With a fixed amount of fluid being within vessel803, it will be appreciated that a decrease in vessel803volume will cause an increase in the pressure of the fluid within vessel803.

Accordingly, the pressure of fluid within vessel803will increase as the inner diameter defined by bladder802decreases. Similarly, if the inner diameter defined by bladder802is increased (e.g., by pushing bladder802back through latch mechanism806), the volume of vessel803will increase, causing a decrease in the pressure of fluid within vessel803. Such changes in pressure may be detected by pressure sensor808and communicated as described above.

In one embodiment, rollers810are passive. In other words, rollers810are configured to rotate freely, and some other mechanism provides movement of bladder802and band804relative to latch mechanism806. Suitable mechanisms for providing movement of bladder802and band804relative to latch mechanism806will be apparent to those of ordinary skill in the art. In another embodiment, rollers810are active. In this embodiment, rollers810are powered (e.g., by a motor, etc.), and are operable to drive bladder802and band804through latch mechanism806. Rollers810of this embodiment may have a high coefficient of friction or other properties. Of course, rollers810in this example are merely illustrative, and any other components or features may be used to squeeze bladder802, drive bladder802and band804through latch mechanism806, and/or serve other purposes. Other variations of gastric band800, including variations of its components, uses, and principles of operation, will be apparent to those of ordinary skill in the art.

Each of the foregoing examples of a gastric band10include versions that are mechanically adjustable. As used herein, the term “mechanically adjustable” shall be read to include gastric bands10or other devices that define an inner diameter (e.g., to form a restriction in a patient) that is adjustable by movement of at least one non-inflating component (e.g., an actuator150, a cable222, a band62, a band602, a band702, rollers810, etc.). Such devices may be contrasted with those whose adjustments are provided merely by expansion or contraction of a fluid-filled member, with no movement of some other component, such as a conventional inflatable gastric band. While the above embodiments are described explicitly in the context of mechanically adjustable devices, it will be appreciated that the embodiments may be varied to include devices that are not mechanically adjustable.

As mentioned above, components of embodiments described herein may be made of non-ferromagnetic materials, allowing the patient to under go Magnetic Resonance Imaging (MRI) without damage to the device or patient. Being MRI safe may avoid limiting the medical procedures which are safely available to patients having implanted bands, etc. Alternatively, components may be made of any other suitable materials.

In addition to use during adjustments, the sensing systems of the foregoing examples may also be used to measure pressure variations, or variations of other parameters, in or a band10at various intervals during treatment. Periodic parameter readings may enable the sensing system to function as a diagnostic tool, to ensure that band10is operating effectively. In particular, a sensing system may be utilized to detect a no pressure condition associated with band10, which may indicate a break or other condition. Alternatively, the system may be used to detect excessive pressure spikes associated with band10, which may indicate a blockage within the stoma or other conditions.

It will become readily apparent to those skilled in the art that the above invention has equally applicability to other types of implantable bands. For example, bands are used for the treatment of fecal incontinence. One such band is described in U.S. Pat. No. 6,461,292 which is hereby incorporated herein by reference. Bands can also be used to treat urinary incontinence. One such band is described in U.S. Patent Application 2003/0105385 which is hereby incorporated herein by reference. Bands can also be used to treat heartburn and/or acid reflux. One such band is described in U.S. Pat. No. 6,470,892 which is hereby incorporated herein by reference. Bands can also be used to treat impotence. One such band is described in U.S. Patent Application 2003/0114729 which is hereby incorporated herein by reference.

The present invention has application in conventional endoscopic and open surgical instrumentation as well as application in robotic-assisted surgery.

While the present invention has been illustrated by description of several embodiments, it is not the intention of the applicant to restrict or limit the spirit and scope of the appended claims to such detail. Numerous other variations, changes, and substitutions will occur to those skilled in the art without departing from the scope of the invention. For instance, the device and method of the present invention has been illustrated in relation to providing the pressure sensor within the injection port. Alternatively, the sensor could be positioned within a fluid filled portion of the band in order to measure pressure changes within the band. Additionally, the pressure sensor could be associated with an elastomeric balloon implanted within the stomach cavity to measure fluid pressure within the balloon. The structure of each element associated with the present invention can be alternatively described as a means for providing the function performed by the element. It will be understood that the foregoing description is provided by way of example, and that other modifications may occur to those skilled in the art without departing from the scope and spirit of the appended Claims.