U.S. patent application number 13/039198 was filed with the patent office on 2011-06-23 for flow control method and device.
This patent application is currently assigned to ALLERGAN, INC.. Invention is credited to Michel BACHMANN, Pierre Fridez, Christian Imbert, Alain Jordan, Jean-Charles Montavon, Nikos Stergiopulos.
Application Number | 20110152608 13/039198 |
Document ID | / |
Family ID | 46303069 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110152608 |
Kind Code |
A1 |
BACHMANN; Michel ; et
al. |
June 23, 2011 |
FLOW CONTROL METHOD AND DEVICE
Abstract
Apparatus and methods are provided comprising an implantable
non-hydraulic ring that encircles and provides a controllable
degree of constriction to an organ or duct and an external control
that powers and controls operation of the ring. The ring includes a
rigid dorsal periphery that maintains a constant exterior diameter,
and a compliant constriction system that reduces intolerance
phenomena. A high precision, energy efficient mechanical actuator
is employed that is telemetrically powered and controlled, and
maintains the ring at a selected diameter when the device is
unpowered, even for extended periods. The actuator provides a
reversible degree of constriction of the organ or duct, which is
readily ascertainable without the need for radiographic imaging.
Methods of use and implantation also are provided.
Inventors: |
BACHMANN; Michel; (Vaux
s/Morges, CH) ; Jordan; Alain; (Ropraz, CH) ;
Fridez; Pierre; (Crissier, CH) ; Montavon;
Jean-Charles; (Lausanne, CH) ; Imbert; Christian;
(Froideville, CH) ; Stergiopulos; Nikos;
(Preverenges, CH) |
Assignee: |
ALLERGAN, INC.
Irvine
CA
|
Family ID: |
46303069 |
Appl. No.: |
13/039198 |
Filed: |
March 2, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10962852 |
Oct 12, 2004 |
7901419 |
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13039198 |
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10672876 |
Sep 25, 2003 |
7148041 |
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10962852 |
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10653808 |
Sep 3, 2003 |
7238191 |
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10672876 |
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Current U.S.
Class: |
600/37 |
Current CPC
Class: |
A61F 5/0063 20130101;
A61F 5/0066 20130101; A61F 5/0053 20130101 |
Class at
Publication: |
600/37 |
International
Class: |
A61F 2/00 20060101
A61F002/00 |
Claims
1. A laparoscopically implanted adjustable gastric banding device
for encircling a stomach of a patient for the treatment of obesity,
comprising: an elongated member having a first end and a second
end, the elongated member configured to make atraumatic contact
with the stomach of the patient when encircling the stomach; a clip
disposed on the first end of the elongated member, the clip having
a slot and a tab; and a flange disposed on the second end of the
elongated member, the flange configured to engage the slot so that
the elongated member encircles an upper part of the stomach of the
patient to form a stoma; wherein the elongated member for
encircling the stomach is configured to have an adjustable interior
diameter facing the stomach and an exterior diameter facing away
from the stomach, the exterior diameter configured to resist
changing when the interior diameter is adjusted.
2. The gastric banding device of claim 1 further comprising a tube
coupled to the elongated member, wherein the tube is configured to
facilitate adjustment of the interior diameter of the elongated
member.
3. The gastric banding device of claim 2 further comprising a pod
coupled to the tube and configured to interface outside the body of
the patient for controlling the adjustment of the interior diameter
of the elongated member.
4. The gastric banding device of claim 1 wherein the elongated
member is configured to encircle the upper part of the stomach of
the patient in a substantially circular loop.
5. A method of laparoscopically implanting a gastric banding device
within an abdominal cavity and around a stomach of a patient, the
method comprising: providing a gastric banding device having an
elongated member, the elongated member having a first end and a
second end, the first end having a slot, the second end having a
flange configured to engage the slot so that the elongated member
encircles the stomach of the patient, wherein the elongated member
encircling the stomach has an adjustable interior diameter facing
the stomach and an exterior diameter facing away from the stomach,
the exterior diameter configured to resist changing when the
interior diameter is adjusted; creating a plurality of incisions
into the abdominal cavity of the patient; establishing a
pneumoperitoneum by insufflating the abdominal cavity of the
patient; inserting a tool into at least one of the plurality of
incisions to create a path for the elongated member around the
stomach; inserting the elongated member into the abdominal cavity;
positioning the elongated member around the stomach of the patient;
and engaging the flange on the second end of the elongated member
with the slot on the first end of the elongated member for wrapping
the elongated member around an upper part of the stomach to form a
stoma.
6. The method of claim 5 wherein the plurality of incisions are
10-18 mm in diameter and further comprising inserting at least one
trocar into at least one of the plurality of incisions.
7. The method of claim 5 wherein positioning the elongated member
around the stomach of the patient comprises using laparoscopic
instruments to grasp the elongated member.
8. The method of claim 5 wherein insufflating the abdominal cavity
of the patient comprises filling the abdominal cavity with carbon
dioxide gas.
9. The method of claim 5 further comprising inserting a camera into
at least one of the plurality of incisions.
10. The method of claim 5 further comprising: providing a pod and a
tube coupled between the pod and the elongated member; inserting
the pod and the tube into the abdominal cavity; and fastening the
pod to a location within the body of the patient.
11. A laparoscopically implanted adjustable gastric banding device
for encircling a stomach of a patient for the treatment of obesity,
comprising: an elongated member having a first end and a second
end, the elongated member configured to make atraumatic contact
with the stomach of the patient along an interior diameter of the
elongated member when encircling the stomach; a clip disposed on
the first end of the elongated member, the clip having a slot; a
flange disposed on the second end of the elongated member, the
flange configured to engage the slot so that the elongated member
encircles an upper part of the stomach of the patient to form a
stoma; and an antenna coupled to the elongated member for enabling
telemetric control of the interior diameter of the elongated
member; wherein the elongated member for encircling the stomach is
configured to have an exterior diameter facing away from the
stomach that resists changes in size during adjustment of the
interior diameter.
12. The gastric banding device of claim 11 further comprising an
external control positioned outside the body of the patient and
configured to provide power and control signals to the antenna for
adjusting the interior diameter of the elongated member.
13. The gastric banding device of claim 12 further comprising a
patient microchip card for storing identification and adjustment
data, the patient microchip card configured to interface with the
external control.
14. The gastric banding device of claim 11 further comprising a
spring coupled with the elongated member for allowing temporary
expansion of the interior diameter of the elongated member during
convulsive activity of the stomach.
15. The gastric banding device of claim 11 further comprising a
reference position switch, the reference position switch activated
when the interior diameter of elongated member is in the fully open
configuration when encircling the stomach.
16. The gastric banding device of claim 11 further comprising: a
tension element slidably positioned within the elongated member;
and an actuator coupled to the antenna, the actuator configured to
engage the tension element within the elongated member for
adjusting the interior diameter of the elongated member.
17. The gastric banding device of claim 16 wherein the tension
element comprises screw threads defining a screw thread pitch.
18. The gastric banding device of claim 17 wherein the actuator
comprises a motor coupled with a nut, the nut configured to
rotatably engage the screw threads of the tension element.
19. The gastric banding device of claim 17 wherein the antenna
telemetrically transmits the interior diameter of the elongated
member to the external control, the interior diameter computed as a
function of the screw thread pitch and the engagement with the
actuator.
20. The gastric banding device of claim 17 wherein the tension
element is configured to maintain a substantially constant screw
thread pitch when the tension element is subjected to bending.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 10/962,852, filed on Oct. 12, 2004,
which is a continuation-in-part of U.S. patent application Ser. No.
10/653,808, filed on Sep. 3, 2003, which claims the benefit of
European Application No. 02019937.8, filed on Sep. 4, 2002. The
entire contents of each of these applications are hereby
incorporated by reference herein.
FIELD
[0002] This invention relates to laparoscopic implants designed to
be implanted in the body of a patient around a biological organ
having a pouch or duct to regulate functioning of the organ or
duct. More specifically, the present invention is directed to an
implantable telemetrically-powered and controlled ring suitable for
use as a gastric band to treat obesity or as an artificial
sphincter.
BACKGROUND
[0003] Obesity refers to a body weight that exceeds the body's
skeletal and physical standards. One well recognized parameter used
to measure obesity is not directly the weight but the Body Mass
Index (BMI) because it takes into account patient height: BMI is
calculated by dividing weight by height squared and is expressed in
kg/m2.
[0004] Obesity is usually defined as a BMI of 30 kg/m2 or greater,
and is further broken down into Class I (BMI of 30-34.9 kg/m2),
Class II (BMI of 35-39.9 kg/m2) also called severe obesity, and
Class III (BMI of 40 kg/m2 or greater), also called extreme
obesity. Obesity is considered "morbid" when the BMI is over 40
(extreme obesity) or the BMI is over 35 (severe obesity) and
serious comorbidities are present.
[0005] Obesity is well recognized as a serious health problem, and
is associated with numerous health complications, ranging from
non-fatal conditions to life threatening chronic diseases.
According to the World Health Organization, the non-fatal, but
debilitating health problems associated with obesity include
respiratory difficulties, chronic musculoskeletal problems, skin
problems and infertility. Life-threatening problems fall into four
main areas: cardiovascular disease problems; conditions associated
with insulin resistance such as type 2 diabetes; certain types of
cancers, especially the hormonally related and large bowel cancers;
and gallbladder disease. Beyond these physiological problems,
obesity has also psychological consequences, ranging from lowered
self-esteem to clinical depression.
[0006] Surgical intervention generally is the treatment of choice
for patients afflicted with morbid obesity. Such intervention not
only mitigates the myriad health problems arising from overweight,
but may reduce the risk of early death of the patient. Left
untreated, morbid obesity may reduce a patient's life expectancy by
ten to fifteen years.
[0007] Morbidly obese patients as a group are poorly adapted to
attain sustainable long-term weight loss using non-surgical
approaches, such as strict diets combined with exercise and
behavioral modification, even though such methods are acknowledged
to be the safest. For this reason, there is a continuing need for
direct intervention to provide effective, long-term treatments for
morbid obesity.
[0008] Three main surgical procedures are currently in use:
Roux-en-Y Gastric Bypass ("RYGB"), Vertical Banded Gastroplasty
("VBG") and Adjustable Gastric Banding ("AGB").
[0009] In RYGB a small stomach pouch is created and a Y-shaped
section of the small intestine is attached to the pouch so that
food bypasses the lower stomach, the duodenum and the first portion
of the jejunum. The RYGB procedure is both restrictive, in that the
small pouch limits food intake and malabsorptive, in that the
bypass reduces the amount of calories and nutrients the body
absorbs.
[0010] VBG employs a non-adjustable synthetic band and staples to
create a small stomach pouch. AGB employs a constricting synthetic
ring that is placed around the upper end of the stomach to create
an artificial stoma within the stomach. The band is filled with
saline solution and is connected to small reservoir/access-port
located under the skin of the abdomen. The AGB band may be
inflated, thereby reducing the size of the stoma, or deflated, thus
enlarging the stoma, by puncturing the access-port with a needle
and adding or removing saline solution. Both VBG and AGB are purely
restrictive procedures, and have no malabsorptive effect.
[0011] An example of the AGB technique is described, for example,
in U.S. Pat. No. 5,074,868 to Kuzmak. As described in that patent,
a flexible band of elastomeric material is implanted around the
stomach to form a closed loop defining a fixed pre-established
diameter. The body of the flexible band includes an expandable
chamber, which is linked via a tube to a subcutaneous injection
port. Fluid may be introduced into the injection port using a
syringe to add or remove fluid from the expandable chamber and thus
vary the internal diameter of the band and the diameter of the
stoma. In this way, expansion of the chamber, in combination with
the pre-established and fixed diameter of the band, permits
adjustment of the stoma diameter and thus regulation of the
quantity of food ingested.
[0012] While the device described in the Kuzmak patent is capable
of providing satisfactory results, it nevertheless-suffers from a
number of drawbacks. The injection port is the source of many of
the problems encountered with the hydraulic gastric bands,
including infection, damage to the tube due to imprecise puncturing
with the needle, discomfort to the patient created by the port and
difficulty in locating the port (often necessitating the use of
x-ray to determine the location and orientation of the port).
[0013] In addition, although the injection port makes it possible
to make limited adjustments to the diameter of the ring without
major surgical intervention, installation of the band may be
accompanied by intolerance phenomena, such as vomiting. This
drawback may arise from various causes, including too great a
reduction in the diameter of the stoma, ineffective action of the
band due to too great a stoma diameter, obstruction, infection or
local or general inflammation.
[0014] Accordingly, it sometimes is necessary to re-operate, either
to relieve the patient or to adjust or change the
previously-implanted band. In such cases, the previously-implanted
band must be cut and either removed or replaced, during operations
that are difficult to carry out, difficult for the patient to
tolerate and costly.
[0015] U.S. Pat. No. 5,938,669 to Klaiber et al. addresses some of
the issues arising from use of an injection port, and describes a
gastric band that is adjusted using a remote control in a
non-invasive manner. The device includes a control box that is
implanted in the body of the patient and coupled to the gastric
band. The control box includes a battery-operated electric pump and
valve that are coupled between an expandable chamber and a fluid
reservoir. The control box also contains a radiofrequency
transceiver and microprocessor, which are arranged to communicate
with an external remote control to control operation of the pump to
add or remove fluid from the reservoir to the expandable chamber,
thereby selectively varying the diameter of the stoma opening. The
external remote control is operated by a physician.
[0016] The device described in Klaiber presents an interesting and
beneficial development for patients, but still suffers from a
number of drawbacks. Implantation of that system's fluid reservoir
into the body of the patient requires a delicate procedure, so as
to avoid puncture and maintain watertightness. Likewise, the
introduction of a battery within the patient's body confers an
undesirable degree of fragility upon the system. For example,
further surgical intervention is required to replace a depleted or
leaking battery.
[0017] Several attempts to overcome drawbacks associated with
hydraulically-actuated gastric bands, such as described in the
Kuzmak and Klaiber patents, are known in the art. For example U.S.
Pat. No. 6,547,801 to Dargent et al. describes a surgically
implanted gastroplasty system having a flexible tractile element
that engages a motor-driven notched pulling member. The motor is
powered and controlled by an inductive circuit, so that the
diameter of the ring may only be changed by operation of the
external remote control.
[0018] Although the system described in the Dargent patent
overcomes problems associated with injection ports used in
previously-known hydraulically-actuated bands and with systems
requiring implantable batteries, it too is expected to suffer from
a number of drawbacks. For example, while Dargent states that the
gearing of the pulling member is sufficient to prevent the band
from unwinding in the unpowered state, the pulling member
configuration still may permit the tractile element to "jump" or
slip if the band is subjected to compression. Further, as shown in
the drawings of that patent, when the band contracts, ripples form
in the interior surface of the band that may cause inflammation or
abrasion of the stomach.
[0019] In addition, it has been observed that within a few weeks of
implantation of a gastroplasty band, fibrous tissue tends to
overgrow and encapsulate the band. It is expected that, as in
Dargent, where the exterior of the diameter of the band contracts
upon actuation of the motor, such fibrous tissue may interfere with
proper functioning of the device. Finally, while the band described
in Dargent is flexible, it has no ability to stretch, for example,
as may be needed to accommodate convulsive motions of the stomach,
e.g., during vomiting, and consequently may lead to patient
intolerance problems.
[0020] All of the foregoing surgical techniques involve major
surgery and may give rise to severe complications. Recent
developments have focused on the use of laparoscopic implantation
of the gastric ring to minimize patient discomfort and recuperation
time.
[0021] For example, U.S. Pat. No. 5,226,429 to Kuzmak describes a
hydraulically-controlled gastric band that is configured to be
implanted using laparoscopic techniques. The band is specially
configured to be inserted through a laparoscopic cannula, and
includes an injection port to control the degree of constriction
imposed by the band. As previously noted, however, that band is
expected to suffer from the same drawbacks as previously-known
hydraulic gastric bands. In addition, that patent provides no
teaching or suggestion as to how non-hydraulically controlled
gastric bands could be configured for laparoscopic implantation.
For example, the patent provides no teaching that would enable a
clinician to adapt the non-hydraulic device described in Dargent
for laparoscopic implantation.
[0022] In view of the foregoing, it would be desirable to provide
apparatus and methods for regulating functioning of a body organ or
duct that provides high precision in a degree of constriction
imposed upon the organ or duct, without the drawbacks associated
with the use of previously-known injection ports.
[0023] It further would be desirable to provide apparatus and
methods for regulating functioning of a body organ or duct that
maintains a desired level of constriction over an extended period
using a gear-driven arrangement that may be implanted
laparoscopically.
[0024] It also would be desirable to provide apparatus and methods
for regulating functioning of a body organ or duct that is capable
of accommodating occasional convulsive motions of the organ or
duct.
[0025] It further would be desirable to provide apparatus and
methods for regulating functioning of a body organ or duct that is
telemetrically powered, so as to avoid the need for re-operation to
replace or repair a defective or depleted energy source.
[0026] It still further would be desirable to provide apparatus and
methods for regulating functioning of a body organ or duct that is
telemetrically controlled, provides a high degree of safety, and
reliably imposes a reproducible degree of constriction.
[0027] It also would be desirable to provide apparatus and methods
for regulating functioning of a body organ or duct that maintains a
constant exterior diameter, and is not rendered inoperative by
tissue ingrowth or fibrous tissue encapsulation.
[0028] It further would be desirable to provide apparatus and
methods for regulating functioning of a body organ or duct that may
be non-invasively, safely and easily adjusted by a physician,
without the need for radiographic imaging.
SUMMARY
[0029] In view of the foregoing, it is an object of the present
invention to provide apparatus and methods for regulating
functioning of a body organ or duct that provides high precision in
a degree of constriction imposed upon the organ or duct, without
the drawbacks associated with the use of previously-known injection
ports.
[0030] It is a further object of the present invention to provide
apparatus and methods for regulating functioning of a body organ or
duct that maintains a desired level of constriction over an
extended period using a gear-driven arrangement that may be
implanted laparoscopically.
[0031] It is another object of this invention to provide apparatus
and methods for regulating functioning of a body organ or duct that
is capable of accommodating occasional convulsive motions of the
organ or duct.
[0032] It is a further object of the present invention to provide
apparatus and methods for regulating functioning of a body organ or
duct that is telemetrically powered, so as to avoid the need for
re-operation to replace or repair a defective or depleted energy
source.
[0033] It is still another object of this invention to provide
apparatus and methods for regulating functioning of a body organ or
duct that is telemetrically controlled, provides a high degree of
safety, and reliably imposes a reproducible degree of
constriction.
[0034] It is yet another object of the present invention to provide
apparatus and methods for regulating functioning of a body organ or
duct that maintains a constant exterior diameter, and is not
rendered inoperative by tissue ingrowth or fibrous tissue
encapsulation.
[0035] It also is an object of this invention to provide apparatus
and methods for regulating functioning of a body organ or duct that
may-be non-invasively, safely and easily adjusted by a physician,
without the need for radiographic imaging.
[0036] These and other objects of the present invention are
accomplished by providing apparatus and methods wherein a
non-hydraulic ring and associated implantable controller are
laparoscopically implanted in the body of a patient, so that the
ring encircles and provides a controllable degree of constriction
to an organ or duct. The ring according to the present invention
comprises a rigid dorsal peripheral portion that maintains a
constant exterior diameter, and a spring portion that facilitates
laparoscopic implantation of the device and provides a degree of
compliance to permit convulsive motion of the organ or duct,
thereby reducing intolerance phenomena.
[0037] In accordance with the principles of the present invention,
the ring includes a high precision, energy efficient mechanical
actuator that maintains the ring at a selected diameter, when the
device is unpowered, for extended durations. The implantable
controller is telemetrically powered and controlled, thereby
eliminating the need for re-operation to repair or replace a
defective or depleted energy source.
[0038] In a preferred embodiment, the ring includes a high
precision motor that imposes a reversible degree of constriction of
the organ or duct by actuation of the motor, wherein the degree of
constriction is readily ascertainable without the need for
radiographic imaging. The ring further comprises a flexible element
having a predefined screw thread pitch that provides a high degree
of precision, while retaining good flexibility. A contact is
provided at the free end of the flexible element that mates with an
electrical switch to establish a reference position for the ring in
the fully opened position.
[0039] In addition, the ring comprises a soft and flexible ePTFE
component, encapsulated in a leak-proof flexible membrane that
maintains a smooth contact surface with the organ or duct, thereby
permitting the ring to undergo considerable diametral contraction
without inducing ripples or bunching in the underlying organ or
duct.
[0040] The ring of the present invention includes a non-invasive,
simple to use external control that may be operated by the
physician, and which may be adjusted during an in-office procedure
without the need for radiographic confirmation. In addition, the
ring and implantable controller are configured to be easily
introduced through a commercially available 18 mm trocar and
implanted using conventional laparoscopic techniques.
[0041] Methods of implanting the apparatus of the present invention
also are provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The foregoing and other objects of the invention will be
apparent upon consideration of the following detailed description,
taken in conjunction with the accompanying drawings, in which like
reference characters refer to like parts throughout, and in
which:
[0043] FIG. 1 is a perspective view of an exemplary ring system of
the present invention including an external control and implantable
ring;
[0044] FIGS. 2A and 2B are, respectively, a schematic diagram,
partly in cross-section, of the gastric band of FIG. 1 and a
sectional view taken along line 2B-2B of FIG. 2A;
[0045] FIGS. 3A and 3B are perspective views illustrating the
degree of constriction attainable by the gastric band of the
present invention between the fully open and fully closed
positions;
[0046] FIGS. 4A and 4B are cross-sectional views of the gastric
band of the present invention along the lines 4A-4A and 4B-4B of
FIGS. 3A and 3B, respectively;
[0047] FIG. 5 is a partial perspective view of a screw thread
portion of the tension element of the present invention;
[0048] FIG. 6 is a perspective view of an entire tension element
suitable for use in the gastric band of the present invention;
[0049] FIG. 7 is a perspective view of the tension element of FIG.
6 coupled to the rigid dorsal peripheral portion and motor housing
of the gastric band;
[0050] FIG. 8 is a perspective view of the gastric band of FIG. 1
straightened and inserted within a standard 18 mm trocar;
[0051] FIG. 9 is a cross-sectional view of an elastomeric housing
of the gastric band depicting the path of the antennae wire and
cavity that accepts the tension element;
[0052] FIG. 10 is a perspective view of the actuator housing,
tension element and actuator of the present invention;
[0053] FIG. 11 is a perspective of the tension element engaged with
the actuator;
[0054] FIG. 12 is a cross-sectional view depicting the construction
of the actuator of FIG. 11;
[0055] FIG. 13 is a cross-sectional view depicting the construction
of the reference position switch;
[0056] FIGS. 14A and 14B are perspective views illustrating the
clip used to close the gastric band into a loop;
[0057] FIG. 15 is a perspective view of the antennae/controller pod
of the present invention;
[0058] FIG. 16 is a cut-away view of the interior of the
implantable antenna/controller pod of FIG. 15;
[0059] FIG. 17 is a cross-sectional view of the antennae cable of
FIG. 15;
[0060] FIG. 18 is a schematic view of the telemetric power and
control circuitry of the present invention;
[0061] FIG. 19 is a detailed view of the signal strength indicator
portion of the remote control of FIG. 1A;
[0062] FIG. 20 is a schematic diagram illustrating placement of the
implantable portion apparatus of the present invention within a
patient; and
[0063] FIGS. 21A-21H are views illustrating a method of
laparoscopically implanting the gastric band of the present
invention.
DETAILED DESCRIPTION
[0064] Referring now to FIG. 1, the banding system of the present
invention is described, comprising external control 10 and
implantable gastric band 21. In the following description reference
will be made, by way of illustration, to a gastric band designed to
be implanted around the stomach to selectively adjust the diameter
of opening of the stoma, and thereby control food intake. Such
regulation has the effect of creating a feeling of satiety in the
patient after relatively little food is consumed, and provides an
effective treatment for morbid obesity.
[0065] It is to be understood, however, that the present invention
is in no way limited to gastroplasty, but on the contrary,
advantageously may be applied to regulate the functioning of other
body organs or ducts, such as in the treatment of gastro-esophageal
reflux disease, urinary or fecal incontinence, colostomy, ileostomy
or to regulate blood flow in connection with isolated organ
perfusion for treatment of cancer. For treatment of urinary
continence, the implantable portion of the system will be implanted
around the bladder or urinary tract, while in the case of fecal
incontinence, the ring may be implanted around a portion of the
gastro-intestinal tracts, such as anal structures of the
intestine.
[0066] System Overview
[0067] With respect to FIG. 1, self-contained external control 10
comprises housing 11 having control panel 12 and display screen 13.
External control 10 includes a digital signal processor and may be
battery-powered or powered using an external power supply, e.g.,
connected to a wall socket. External antenna 14 is coupled to
remote control 10 via cable 15. As described more fully with
respect to FIG. 18, external control 10 includes a microprocessor
that controls the emission of radiofrequency signals to the gastric
band 10 to both control and power operation of the band.
[0068] External control 10 accepts patient microchip card 16, which
corresponds to the specific gastric band implanted in the patient,
and stores data, such as the implant identification number,
adjustment parameters (e.g., upper and lower limits of an
adjustment range, etc.) and information regarding the last
adjustment position of the ring. External control 10 includes
signal strength indicator 17, as described hereinbelow with respect
to FIG. 19, ON/OFF button 18, OPEN button 19a, CLOSE button 19b,
COUPLING button 19c and menu options panel 20.
[0069] During use of the device, the physician need only turn
external control 10 ON using button 18, position external antenna
14 over patient's chest above antenna/controller pod 23, check the
coupling by depressing COUPLING button 19c, and when the coupling
is sufficient, adjust the degree of constriction using OPEN button
19a or CLOSE button 19b. The diameter of the band is continually
displayed on display panel 13 with a precision of about 0.1 mm for
the entire range of diameters of the ring, e.g., from 19 mm fully
closed to 29 mm fully opened.
[0070] Still referring to FIG. 1, gastric band 21 of the present
invention now is described, and includes ring 22 coupled to
implantable antenna/controller pod 23 via cable 24. Pod 23 includes
removable tag 25 that may be used to laparoscopically position ring
22. Ring 21 includes first end 26 having clip 27 that slides over
and positively engages second end 28 of the ring.
[0071] As described in detail below, ring 22 is configured to be
straightened to pass through the lumen of a commercially available
18 mm trocar for delivery in a patient's abdomen. Tag 25, pod 23
and cable 24 then are passed through clip 27 to form the ring into
a substantially circular loop around an upper portion of the
patient's stomach, thereby reducing the diameter of the opening of
the stomach. In its undeformed shape, ring 22 assumes a circular
arc configuration that facilitates positioning of the ring around
the stomach and also in self-guiding the clipping procedure.
[0072] Ring 22 of the present invention comprises a flexible
tubular band having a smooth, flexible and elastic membrane, thus
ensuring atraumatic contact with the patient's stomach tissue that
is easily tolerated. When engaged with dorsal element 38, membrane
39 is stretched by an appropriate factor (i.e., 20%-40%), so that
when ring 22 is in its fully closed position, little or no
wrinkling appears on the membrane surface. Ring 22 has
approximately the shape of a torus of revolution of substantially
cylindrical cross-section. Alternatively, ring 22 may have any
other suitable cross-section, including rectangular. Housing 29 on
second end 28, clip 27 on first end 26 and dorsal peripheral
portion 30 of ring 22 (indicated by the darker portions of ring 22
of FIG. 1), preferably comprise a biocompatible material such as
silicone. Interior portion 31 of ring 22 preferably comprises
expanded polytetrafluoroethylene (ePTFE), which permits
longitudinal contraction without bunching or ripples, and is
covered by a thin membrane of protective material, for example,
based on or made of silicone.
[0073] Advantageously, as depicted in FIG. 1, portions of ring 22
employ polymeric components having different colors to facilitate
laparoscopic manipulation and implantation. In one preferred
embodiment, interior portion 31 of the ring comprises lighter
colored materials while the clip 27 and housing 29 comprise darker
colored materials, thereby indicating to the clinician which
portions of ring 22 may be grasped during implantation. In
particular, the colors may consist of black, white and different
shades of gray achievable with implantable silicone.
[0074] Implantable Ring
[0075] Referring now to FIGS. 2A and 2B, the internal structure of
ring 22 is described. In particular, as depicted in FIG. 2A, ring
22 includes flexible tension element 32 having fixed end 33 mounted
to first end 26 of the ring and free end 34 that is engaged with
motor-driven actuator 35 and extends into a cavity in housing 29.
Tension element 32 is slidingly disposed within a substantially
cylindrical tube of compressible material 36, e.g., ePTFE, as
illustrated in FIG. 2B, so that when tension element is pulled
through actuator 35, compressible material 36 is compressed and the
diameter of opening 37 is reduced. Compressible material 36
preferably is surrounded on its dorsal face with a flexible, but
sturdier elastomeric material, such as silicone element 38. Both
compressible material 36 and silicone element 38 preferably are
enclosed within a membrane of elastomeric biocompatible material
39, as shown in FIG. 2B, to prevent tissue ingrowth between the
ePTFE tube and silicone element 38. Membrane 39 may be affixed to
dorsal element 38 using a biocompatible glue to prevent leakage in
case of accidental puncture on the dorsal surface.
[0076] In accordance with one aspect of the present invention, ring
22 further comprises layer 40 of a relatively rigid material
disposed on the dorsal periphery of the ring. Layer 40, which may
comprise a plastic or metal alloy, prevents the exterior diameter
of ring 22 from changing during adjustment of tension element to
reduce internal diameter 37 of the ring. Layer 40, by its
structural rigidity, imposes a circular arc shape for the entirety
of ring 22. Advantageously, layer 40 allows the tension element to
be adjusted following encapsulation of the gastric ring by fibrous
tissue after implantation, since adjustment of internal diameter 37
of the gastric ring does not change the external diameter of the
ring.
[0077] The foregoing feature is illustrated in FIGS. 3 and 4. In
FIGS. 3A and 3B, ring 22 is shown in its fully open and fully
closed positions, respectively. As discussed above, layer 40 forms
a rigid skeleton that permits the internal diameter of the ring to
change while maintaining the external diameter constant. Radial
movement of tension element 32 is transmitted to membrane 39 by
compressible material 36. ePFTE is particularly well-suited for use
as compressible material 36 because it can undergo a 3:1 reduction
in length without experiencing a significant increase in
cross-section.
[0078] Accordingly, as depicted in FIGS. 4A and 4B, increase or
reduction of the length of tension element 32 results in reversible
radial displacement at the internal periphery of the ring opposite
the dorsal periphery. This in turn translates into a variation of
internal diameter D of the ring from a fully open diameter to a
fully closed diameter. Preferably, the fully open diameter is about
35 mm, and the fully closed diameter is about 15 mm. More
preferably, the fully open diameter is about 29 mm, and the fully
closed diameter is about 19 mm.
[0079] Referring now to FIG. 5, tension element 32 is described.
Tension element 32 preferably has sufficient flexibility to permit
it to be formed into a substantially circular shape of the ring,
while also being able to transmit the force necessary to adjust the
ring diameter. Tension element 32 therefore comprises flexible core
41, preferably a metal alloy wire of circular cross section, on
which is fixed, and wound coaxially, at least one un-joined coil
spring which defines the screw thread pitch.
[0080] As shown in FIG. 5, tension element 32 preferably comprises
two un-joined coil springs that form a screw thread: first spring
42, wound helicoidally along the flexible core 41, and second
spring 43 of greater exterior diameter. Second spring 43 preferably
comprises coils 44 of rectangular transverse section, so as to
delineate a flat external generatrix. First spring 42 is interposed
between coils 44 of the second spring 43 to define and maintain a
substantially constant square screw thread pitch, even when the
tension element is subjected to bending.
[0081] As a consequence of the foregoing arrangement, the ability
of tension element 32 to maintain a substantially constant thread
pitch, when subjected to bending, confers great precision on
adjustments of ring 22. This is especially so when it is realized
that as the tension element is drawn through actuator 35, an
ever-increasing curvature is imposed on the remaining portion of
the tension element. However, because the foregoing arrangement of
un-joined coils maintains a substantially constant screw thread
pitch, the energy needed to drive actuator 35 remains low and the
efficiency of energy transmission resulting from the use of a
square screw thread pitch remains high. In addition, the use of a
square screw thread pitch guarantees a stable adjustment position
even when the actuator is unpowered.
[0082] Second spring 43 advantageously may be made by laser cutting
a cylindrical hollow tube, e.g., made from stainless steel, or
alternatively, by winding a wire with a rectangular, trapezoidal or
other cross-section. When helically interwound with first spring
42, coils 44 of second spring 43 are naturally activated with an
intrinsic elastic compression force from the adjacent coils of
first spring 42. As will of course be appreciated, first spring 42
is fixedly joined to flexible core 41 at one end. At the second
end, crimped cap 45 (see FIG. 6) is located a short distance from
the ends of springs 42 and 43 to allow for small extensions (to
accommodate flexion of tension element 32), but also to limit this
extension to keep the thread pitch substantially constant.
[0083] Referring now to FIG. 6, the entirety of tension element 32
is described. Free end 34 includes crimped cap 45, second spring 43
having coils with a square transverse section, and first spring 42
(not visible in the figure, but intertwined between the coils of
second spring 43). Flexible core 41 extends through first and
second springs 42 and 43, and terminates close to cap 45. In
accordance with one aspect of the present invention, tension
element 32 further comprises third spring 46 that is coupled to
flexible core 41, and first and second springs 42 and 43 at
junction 47. Third spring 46 includes loop 48 at the end opposite
to junction 47, which permits the tension element to be mounted to
first end 26 of ring 22.
[0084] In accordance with the principles of the present invention,
third spring 46 is relatively stiff, but provides a needed degree
of compliance to the tension element. Whereas previously-known
elastomeric bands provide a small degree of compliance,
previously-known non-hydraulic gastric bands, such as disclosed in
the above-mentioned Dargent patent have no compliance.
Consequently, in the presence of vomiting, which is a frequent
complication of gastric bands, previously-known gastric bands
prevent convulsive stomach motion, which may result in extreme
discomfort to the patient. In the present invention, however, third
spring 46 permits the gastric band to temporarily expand due to
convulsive activity, and afterwards return to the preselected
internal diameter. This feature is expected to significantly reduce
patient discomfort and intolerance phenomena.
[0085] With respect to FIG. 7, tension element 32 is shown disposed
within skeleton 50 of the gastric ring 22. Skeleton 50 includes
layer 51 that forms the dorsal periphery (corresponding to layer 40
of FIGS. 2 and 4), anchor 52 that accepts loop 48 of tension
element 32, and actuator housing 53. Skeleton preferably comprises
a high strength moldable plastic. As further depicted in FIG. 7,
skeleton 50 extends along a greater arc length than tension element
32. In accordance with another aspect of the present invention,
third spring 46 permits gastric band 21 to be straightened for
insertion through a standard 18 mm trocar, despite the differential
elongation of the skeleton and tension element. This feature is
illustrated in FIG. 8, which depicts ring 22 inserted through 18 mm
trocar 55 so that the ring is substantially straight.
[0086] Referring now to FIG. 9, housing 29 of the free end of ring
22 is described. Housing 29 comprises an elastomeric material, such
as silicone, having recessed portion 56, tension element cavity 57
and cable lumen 58. Recess 56 is configured to accept actuator
housing 53 of skeleton 50, so that as tension element 32 is drawn
through actuator 35 it extends into tension element cavity 57.
Cable lumen 58 extends through housing 29 so that cable 24 may be
coupled to actuator 35. Housing 29 preferably may be grasped in
area G using atraumatic laparoscopic graspers during manipulation
of the device.
[0087] In FIG. 10, actuator housing 53 of skeleton 50 is shown with
actuator 35 and tension element 32 disposed therethrough. Antenna
cable 24 is coupled to motor (not shown) disposed within actuator
housing 53. Tension element 32 is in the fully opened (largest
diameter) position, so that crimped cap 45 contacts printed circuit
board 59 of the reference position switch, described below with
respect to FIG. 13.
[0088] Actuator
[0089] With respect to FIGS. 11 and 12, actuator 35 includes motor
66 coupled to antenna cable 24 that drives nut 60 through gears 61.
Nut 60 is supported by upper and lower bearings 62 to minimize
energy losses due to friction. Nut 60 is self-centering,
self-guiding and provides high torque-to-axial force transfer.
Moreover, nut 60 is expected to be more reliable than tangent screw
arrangements employed in previously-known mechanical gastric rings,
and cannot jump or slip. In addition, nut 60 is self-blocking,
meaning that nut 60 will not rotate due to the application of
pushing or pulling forces on tension element 32. This condition may
be achieved by ensuring that the height (h) of the thread divided
by the circumference of the screw (2.pi.R) is less than the
arctangent of the friction coefficient (.mu.):
h/(2.pi.R)<arctan(.mu.).
[0090] Gears 61 preferably are selected to provide good mechanical
efficiency, preferably with a reduction factor greater than 1000.
In addition, the volume of the actuator depicted in FIGS. 11 and 12
may be quite small, with a total volume less than 1 cm.sup.3 and a
diameter less than 12.5 mm, so that the device may easily pass
through a standard trocar. In a preferred embodiment, gears 61 are
selected to provide a force of more than 2 kg on the screw thread
of the tension element at an electrical consumption of only 50 mW.
The gears and other components of actuator 35 preferably are made
of stainless steel or are gold plated to permit operation in the
high humidity likely to be encountered in a human body.
[0091] Motor 66 employed in actuator 35 preferably comprises a
Lavet-type high precision stepper motor with a flat magnetic
circuit, such as are used in watches. The motor preferably is a two
phase (two coil) motor that permits bi-directional rotation, has
good efficiency, and may be supplied with a square wave signal
directly by the microcontroller circuitry within antenna/controller
pod 35, thus eliminating the need for an interface circuit.
Alternatively, the motor employed in actuator 35 may be of a
brushless DC type motor. In addition, the motor preferably is
compatible with magnetic resonance imaging, i.e., remains
functional when exposed to strong magnetic fields used in medical
imaging equipment.
[0092] Referring now to FIG. 13, the reference position switch of
the present invention is described. Because the actuator of the
present invention employs nut 60 driven by a stepper motor, there
is no need for the system to include a position sensor or encoder
to determine the length of tension element 32 drawn through the
actuator. Instead, the diameter of ring 22 may be directly computed
as a function of the screw thread pitch and the number of rotations
of nut 60. To ensure an accurate calculation of the degree of
restriction imposed by the gastric ring, however, it is desirable
to provide at least one reference point.
[0093] This reference datum is accomplished in the gastric ring of
the present invention using a reference position switch that is
activated when ring 22 is moved to its fully open position. Crimped
cap 45 on the free end of tension element 32 serves this function
by contacting electrical traces 63 on printed circuit board 59 (and
also limits elongation of the screw thread). Circuit board 59 is
disposed just above bearing 65, which forms part of actuator 35
(see also FIG. 10). When crimped cap 45 contacts traces 63 it
closes a switch that signals the implantable controller that the
gastric ring is in the fully open position.
[0094] Ring Closure System
[0095] With respect to FIGS. 14A and 14B, a preferred embodiment of
clip 27 for securing the gastric band in the closed position is
described. Clip 27 on first end 26 of the gastric ring includes
aperture 70, tab 71 having hinge 72 and slot 73. Aperture 70 is
dimensioned to accept second end 28 therethrough, while slot 73 is
dimensioned to accept flange 74 disposed on second end 28.
[0096] To close ring 22, clip 27 is grasped by the tab 71 and tag
25 of pod 23 (see FIG. 1) is inserted through aperture 70. Clip 27
is then pulled towards second end 28 so that housing 29 passes
through aperture 70 while housing 29 is grasped with atraumatic
forceps; the conical shape of housing 29 facilitates this action.
Force is applied to tab 71 until slot 73 captures flange 74,
thereby securing the gastric ring in the closed position. The
physician may subsequently choose to disengage slot 73 from flange
74 by manipulating tab 71 using laparoscopic forceps, for example,
to reposition the ring. Advantageously, however, forces
inadvertently applied to tab 71 in an opposite direction will cause
tab 71 to buckle at hinge 72, but will not cause flange 74 to exit
slot 73. Accordingly, hinge 72 of tab 71 prevents accidental
opening of clip 70 when the tab 71 is subjected to forces that
cause the tab to fold backwards away from body 29, such as may
arise due to movement of the patient, the organ, of or bolus of
fluid passing through the organ.
[0097] Antenna/Controller Pod
[0098] With respect to FIGS. 15 and 16, antenna/controller pod 23
of the present invention is described. Pod 23 is disposed at the
distal end of cable 24 and includes removable tag 25 and holes 75.
Tag 25 comprises a grip structure that facilitates manipulation and
placement of the pod during implantation; after which the tag is
removed using a scissors cut. Tag 25 also includes hole 25b that
allows the use of a suture thread to assist in passing the
antenna/controller pod 23 behind the stomach. Holes 75 also are
dimensioned to be compatible with standard suture needles from size
1-0 to 7-0 to permit pod 23 to be sutured to the patient's sternum,
thereby ensuring that pod 23 remains accessible to the external
antenna and cannot migrate from a desired implantation site.
[0099] As shown in FIG. 16, antenna/controller pod 23 encloses
printed circuit board 76 that carries the antenna and
microcontroller circuitry of gastric band 22. The antenna receives
energy and commands from external control 10 (see FIG. 1), and
supplies those signals to the microcontroller, which in turn powers
motor 66 of actuator 35. The circuitry of antenna/controller pod 23
uses the energy received from the incoming signal to power the
circuit, interprets the commands received from external control 10,
and supplies appropriate signals to the motor of actuator 35. The
circuit also retrieves information regarding operation of the motor
of actuator 35 and relays that information to external control 10
via the antenna. The circuit board preferably is covered with a
water-resistant polymeric covering, e.g., Parylene, to permit use
in the high (up to 100%) humidity environment encountered in the
body.
[0100] Antenna/controller pod 23 includes a mechanical closure
system that is augmented by silicone glue so that the pod is fluid
tight. This silicone glue also is used to protect soldered wires 79
from humidity. The pod preferably is small, e.g., 16 mm.times.33
mm.times.4 mm, to ensure compatibility with a standard 18 mm trocar
and so as to be compatible with placement on the sternum. The pod
preferably has a smooth, atraumatic shape to avoid tissue damage,
has good mechanical strength to withstand handling with surgical
graspers and to prevent mechanical deformation to the printed
circuit board, and has good electromagnetic permeability to allow
efficient energy transmission through the pod. Antenna/controller
pod 23 preferably has a relatively thin planar configuration to
avoid rotation of the pod when placed under the skin, and may
include holes that permit the pod to be sutured in position.
[0101] With respect to FIG. 17, antenna cable 24 is shown in
cross-section. Cable 24 preferably is a coaxial shielded cable
encapsulated in a silicone tube 77 to provide biocompatibility.
Tube 77 is selected to provide leak-proof encapsulation, with
sufficient strength to permit the cable to be manipulated with
atraumatic graspers. Braided shield 78 of the cable prevents
longitudinal deformation of the cable, and surrounds five helically
wound insulated wires 79. Four of wires 79 are used to supply power
to the micromotor of actuator 35; the remaining wire and braided
shield 78 are used to supply a signal from the reference position
switch to the controller.
[0102] As discussed above with respect to FIG. 1, the gastric band
according to the present invention provides an integrated system
for regulating food ingestion in the stomach of a patient, wherein
variation of the diameter of the gastric ring may be adjusted
without any invasive surgical intervention. To accomplish this,
actuator 35 is linked to subcutaneous antenna/controller pod 23 to
receive a radio frequency control and power signal. In the
preferred embodiment, the motor of the actuator has no internal
energy supply, but rather is powered by the receiving circuit of
the antenna through a rechargeable energy storage device, such as a
capacitor. In particular, the receiving circuit converts radio
frequency waves received from external control 10 via the antenna
into a motor control and power signal. In an alternative, although
less preferred, embodiment the actuator may be driven via an
implantable rechargeable battery.
[0103] Power and Control Circuitry
[0104] Referring to FIG. 18, a presently preferred embodiment of
the circuitry employed in external control 10 and gastric band 22
of the present invention is described, based on the principle of
passive telemetry by FM-AM absorption modulation. External control
10 is shown on the left hand side of FIG. 18, and includes
microprocessor 80 coupled to control panel 12 and display 13 (see
FIG. 1). External control 10 produces a signal comprising one or
more data bytes to be transmitted to the implantable
antenna/controller pod 23 and actuator 35 (shown on the right hand
side of FIG. 18).
[0105] External control 10 includes modulator 81 for amplitude
modulation of the RF wave from RF generator 82, which signal is
emitted by the external antenna 14. The emitted wave is received by
the antenna 83 in the antenna/controller pod 23, where AM
demodulator 84 extracts the data bytes from the envelope of
received RF signal. The data bytes then are decoded and written
into an EEPROM of microcontroller 85. A special code is used that
allows easy decoding of the data by microcontroller 85, but also
provides maximal security against communication failure.
[0106] External oscillator 86, which is a voltage controlled
oscillator (VCO), provides a clock signal to microcontroller 85.
Oscillator 86 may consist of, for example, a relaxation oscillator
comprising an external resistor-capacitor network connected to a
discharging logic circuitry already implemented in the
microcontroller or a crystal oscillator comprising a resonant
circuit with a crystal, capacitors and logic circuits. The former
solution requires only two additional components, is suitable when
the stability of the frequency is not critical, and has low current
consumption; the latter solution provides a more stable frequency,
but requires a greater number of additional components and consumes
more power. Oscillator 86 preferably comprises the external RC
network, due to its simplicity.
[0107] Microcontroller 86 interprets the received instructions and
produces an output that drives the motor of actuator 35. As
discussed above, actuator 35 comprises a bi-directional stepper
motor that drives nut 60 through a series of reducing gears.
Preferably, the two coils of the stepper motor of actuator 35 are
directly connected to microcontroller 85, which receives the
working instructions from demodulator 84, interprets them and
provides the voltage sequences to the motor coils. When the supply
of voltage pulses to the stepper motor stops, the gears are
designed to remain stationary, even if a reverse torque or force is
applied to nut 60 by tension element 32.
[0108] As also described above, use of a stepper motor in actuator
35 makes it is possible to obtain positional information on nut 60
and tension element 32 without the use of sensors or encoders,
because the displacement of the tension element is proportional to
the number of pulses supplied to the stepper motor coils. Two
signals are employed to ensure precise control, reference position
signal S.sub.RP, generated by the reference position switch of FIG.
13, and the actuator signal S.sub.A.
[0109] According to one preferred embodiment, signal S.sub.A is the
voltage signal taken at one of the outputs of microcontroller 85
that is connected to the motor coils of actuator 35. Alternatively,
signal S.sub.A could be derived from the current applied to a motor
coil instead of the voltage, or may be an induced voltage on a
secondary coil wrapped around one of the motor coils of actuator
35. In either case, signal S.sub.A is a pulsating signal that
contains information on the number of steps turned by the rotor and
further indicates whether blockage of the mechanism has occurred.
Specifically, if the rotor of the stepper motor fails to turn, the
magnetic circuit is disturbed, and by induction, affects signal
S.sub.A, e.g., by altering the shape of the signal. This
disturbance can be detected in the external control, as described
below.
[0110] Signals S.sub.A and S.sub.RP are converted into frequencies
using external oscillator 14, so that the voltage level of signal
S.sub.A applied to external oscillator 86 causes the oscillator to
vary its frequency F.sub.osc proportionally to the signal S.sub.A.
Thus, F.sub.osc contains all the information of signal S.sub.A.
When crimped cap 45 and tension element 32 are in the reference
position (gastric ring 22 is fully open), the reference position
switch produces reference position signal S.sub.RP. Signal S.sub.RP
is used to induce a constant shift of the frequency F.sub.osc,
which shift is easily distinguishable from the variations due to
signal S.sub.A. If oscillator 86 is a relaxation oscillator, as
described above, signals S.sub.A and S.sub.RP modify the charging
current of the external resistor capacitor network. In this case,
the relaxation oscillator preferably comprises an external
resistor-capacitor network connected to a transistor and a logic
circuit implemented in microcontroller 85. With S.sub.A and
S.sub.RP, the goal is to modify the charging current of the
capacitor of the RC network to change the frequency of the
relaxation oscillator. If the charging current is low, the voltage
of the capacitor increases slowly and when the threshold of the
transistor is reached, the capacitor discharges through the
transistor. The frequency of the charging-discharging sequence
depends on the charging current.
[0111] If oscillator 86 is a crystal oscillator, signals S.sub.A
and S.sub.RP modify the capacitor of the resonant circuit. In this
case, the crystal oscillator circuit preferably comprises a crystal
in parallel with capacitors, so that the crystal and capacitors
form a resonant circuit which oscillates at a fixed frequency. This
frequency can be adjusted by changing the capacitors. If one of
these capacitors is a Varicap (a kind of diode), it is possible to
vary its capacitance value by modifying the reverse voltage applied
on it, S.sub.A and S.sub.RP can be used to modify this voltage.
[0112] In either of the foregoing cases, signals S.sub.A and
S.sub.RP are used to modify at least one parameter of a
resistor-capacitor (RC) network associated with the oscillator 14
or at least one parameter of a crystal oscillator comprising the
oscillator 14.
[0113] Referring still to FIG. 18, signals S.sub.A and S.sub.RP,
derived from the stepper motor or from the output of the
microcontroller 85, may be used directly for frequency modulation
by the oscillator 86 without any encoding or intervention by the
microcontroller 85. By using oscillator 86 of microcontroller 85 as
part of the VCO for the feedback signal, no additional components
are required, and operation of micro controller 85 is not adversely
affected by the changes in the oscillator frequency F.sub.osc. The
oscillating signal F.sub.osc drives voltage driven switch 87 for
absorption modulation, such that feedback transmission is performed
with passive telemetry by FM-AM absorption modulation.
[0114] More specifically, signal F.sub.osc drives switch 87 such
that during the ON state of the switch 87 there is an increase in
energy absorption by RF-DC converter 88. Accordingly, therefore the
absorption rate is modulated at the frequency F.sub.osc and thus
the frequency of the amplitude modulation of the reflected wave
detected by external control 10 contains the information for signal
S.sub.A. As discussed below, pickup 90 in external control 10
separates the reflected wave where it can be decoded by FM
demodulation in demodulator 90 to obtain signal S.sub.A'. This
method therefore allows the transmission of different signals
carried at different frequencies, and has the advantage that the ON
state of switch 87 can be very short and the absorption very strong
without inducing an increase in average consumption. In this way,
feedback transmission is less sensitive to variation in the quality
of coupling between the antennas 83 and 14.
[0115] In external control 10, the feedback signal F.sub.osc is
detected by the pickup 89 and fed to FM demodulator 90, which
produces a voltage output V.sub.OUT that is proportional to
F.sub.osc. V.sub.OUT is fed to filter 91 and level detector 92 to
obtain the information corresponding to the actuator signal
S.sub.A, which in turn corresponds to the pulses applied to the
stepper motor coil. Microprocessor 80 counts these pulses to
calculate the corresponding displacement of the tension element 32,
which is proportional to the number of pulses.
[0116] Signal V.sub.OUT also is passed through analog-to-digital
converter 93 and the digital output is fed to the microprocessor
80, where signal processing is performed to detect perturbations of
the shape of the feedback signal that would indicate a blockage of
the rotor of the stepper motor. Microprocessor 80 stops counting
any detected motor pulses when it detects that the actuator is
blocked, and outputs an indication of this status. Level detector
94 produces an output when it detects that the demodulated signal
V.sub.OUT indicates the presence of the reference position signal
S.sub.RP due to activation of the reference position switch. This
output induces a reset of the position of the tension element
calculated by microprocessor 80 in the external control. In this
way, a small imprecision, e.g. an offset, can be corrected.
[0117] As described above, external control 10 transmits both
energy and commands to the implantable controller circuitry in
antenna/controller pod 23. External control 10 also receives
feedback information from the implantable controller that can be
correlated to the position of the tension element and the diameter
of the ring. As will be apparent to one of skill in the art,
external control 10 and the implantable controller are configured
in a master-slave arrangement, in which the implantable controller
is completely passive, awaiting both instructions and power from
external control 10.
[0118] Operational Modes
[0119] Referring to FIG. 19, some of the safety features of the
system of the present invention are described. As discussed above
with respect to FIG. 18, both power and control signals are
provided to the implantable controller from external control 10.
Because power is delivered to the implantable controller via
magnetic induction, the amount of energy delivered to the
controller depends on the quality of the coupling between external
antenna 14 and the antenna circuitry contained within
antenna/controller pod 23.
[0120] The quality of the coupling may be evaluated by analyzing
the level of the feedback signal received by external control 10,
and a metric corresponding to this parameter may be displayed on
signal strength indicator 17, which includes 6 LEDs (corresponding
to six levels of coupling). If the coupling between the antennae is
insufficient, the motor of actuator 35 may not work properly,
resulting in an inaccurate adjustment of gastric band 21.
[0121] Accordingly, in a standard mode of operation, adjustment may
be made only if the coupling quality is strong enough, as indicated
by having at least LED 5 or LED 6 in FIG. 19 illuminated. If, on
the other hand, poor coupling exists (e.g., one of the first four
LEDs are illuminated) it is still possible to perform some
adjustment of the device, although the adjustment may be
inaccurate.
[0122] The design of external control 10, in combination with
patient microchip card 16 (see FIG. 1), also ensures a high degree
of efficacy and safety. First, as contemplated for use with gastric
band 21 of the present invention, external control 10 is intended
primarily for use by a physician in an office or hospital setting,
and not by the patient alone. Of course, in alternative
embodiments, such as to treat urinary or fecal incontinence, it
would be essential to provide an external control for use by the
patient. The simplicity of the design of the external control and
ease of use would provide no impediment to use by the patient for
such embodiments.
[0123] As discussed with respect to FIG. 1, patient microchip card
16 stores, among other data, a serial number identifying a
corresponding gastric band and the diameter of the ring upon
completion of the previous adjustment. When the external control
first transmits energy to the implantable controller of the gastric
band, the gastric band identifies itself to the external control.
In the standard mode of operation, the serial number stored on the
patient microchip card must match that received from the gastric
band, otherwise no adjustment is permitted.
[0124] As a failsafe, however, the physician still may adjust the
gastric band even if the patient has lost or misplaced his
microchip card. In this case, the external control may be set in a
"no card mode." In this mode, the information displayed on display
13 of the exterior control corresponds only to the relative
variation of the gastric band during that adjustment session, and
is no longer indicative of absolute diameter. When the physician
activates this mode, an emergency bit is set in the memory of the
implantable controller to indicate the "no card mode." In
subsequent adjustment sessions, the implantable controller will
signal that the gastric band was adjusted in the "no card mode" and
all further adjustments will be reported on a relative basis. If
the patient again locates the microchip card, the emergency bit may
be cleared by fully opening the gastric band and thus reaching the
reference contact, which re-initializes the position. Subsequent
adjustments will again be managed in the standard mode of
operation.
[0125] During adjustment of the gastric ring physician places
external antenna 14 in a face-to-face position on the skin of the
patient relative to antenna/controller pod 23 of the gastric ring,
and to receive feedback information from which the constricted
diameter of the gastric ring may be computed. In accordance with
the principles of the present invention, it is possible to vary the
diameter of the gastric ring without having to undertake invasive
surgical intervention, and this variation may be carried out at
will, because multiple control cycles may be carried out at regular
or irregular intervals, solely under the control of the treating
physician.
[0126] The gastric band system of the present invention is expected
to be particularly reliable, relative to previously-known hydraulic
bands that can be adjusted by the patient, because only the
physician typically will have access to the external control box
needed to adjust the ring. For a ring embodiment intended for
treatment of morbid obesity, the patient therefore does not have
free access to any means to adjust the diameter of the ring.
[0127] Moreover, because the gastric band of the present invention
provides a precise readout of the current diameter of the ring in
the standard mode of operation, it may not be necessary for the
patient to ingest a radiographic material (e.g., barium dye) to
permit radiographic visualization of the ring to confirm the
adjusted size. The process of adjusting the band accordingly may be
carried out in a doctor's office, without the expense associated
with radiographic confirmation of such adjustments. In addition,
the self-blocking configuration of the tension element and nut, in
combination with the mechanical nature of the gastric band,
overcome problems associated with previously-known
hydraulically-actuated gastric band systems.
[0128] Methods of Implantation and Removal
[0129] Referring now to FIG. 20, gastric band 21 of the present
invention is shown implanted in a patient. Ring 22 is disposed
encircling the upper portion of the patient's stomach S while
antenna/controller pod 23 is disposed adjacent to the patient's
sternum ST. Pod 23 is located in this position beneath the
patient's skin SK so that it is easily accessible in the patient's
chest area to facilitate coupling of the pod 23 to external antenna
14 of external control 10 (see FIG. 1).
[0130] Referring to FIGS. 21A to 21H, a method of implanting the
gastric band of the present invention is described. The method is
similar to laparoscopic procedures used to implant previously-known
hydraulically-actuated gastric bands. Access to the abdomen is
obtained by using 4 to 6 small holes, generally 10 to 18 mm in
diameter, with a trocar inserted in each hole, as depicted in FIG.
21A. A camera and laparoscopic surgical tools are introduced and
manipulated through the trocars. In addition, to permit free motion
of the surgical tools and camera, the abdomen is inflated with
CO.sub.2 to an overpressure of approximately 0.15 bars.
[0131] In FIGS. 21B-21E, the gastric band of the present invention
is straightened (as depicted in FIG. 8) and inserted, antenna
first, into the abdomen through an 18 mm trocar. Alternatively, a
laparoscopic cannula may be used to make an incision and then
withdrawn, and the device inserted through the opening so created
(other instruments also may be used to form this laparotomy). In
FIG. 21B, tag 25 of antenna/controller pod 23 is shown entering the
abdomen through trocar 100 using atraumatic graspers 110. In FIG.
21C, housing 29 of the gastric ring is shown being drawn into the
abdomen through trocar 100, again using atraumatic graspers 110.
FIG. 21D shows ring 22 entering the abdomen in an extended
position. In FIG. 21E, the ring is permitted to resume its
preferred ring shape.
[0132] Ring 22 then is manipulated using atraumatic graspers 100
(as described above with respect to FIGS. 14A and 14B) to secure
the gastric ring around the upper portion of the patient's stomach
until slot 73 of clip 27 is engaged with flange 74, as shown in
FIG. 21F. A fold of stomach tissue then may be sutured around the
gastric ring to prevent migration of the gastric band, as is
typical for hydraulically-actuated gastric bands.
[0133] Finally, as shown in FIG. 21G, a channel may be formed
through the abdominal wall and antenna/controller pod 23 passed
through the channel. Tag 25 then is cut off of antenna/controller
pod 23, and the pod is sutured into position above the patient's
sternum, as depicted in FIG. 21H. The trocars then are removed, and
the gastric band may be activated to adjust the diameter of the
ring as desired by the physician.
[0134] The process of removing the gastric ring of the present
invention involves substantially reversing the sequence of steps
described above, and may be accomplished non-destructively. In
particular, a plurality of cannulae into the abdominal cavity and
the abdominal cavity then insufflated to create a pneumoperitoneum.
Using laparoscopic graspers, the clip of the gastric ring may be
unclipped and the elongated member removed from a position
encircling the patient's stomach. The gastric ring may then be
straightened and withdrawn from the abdominal cavity either through
one of the plurality of cannulae or via a laparotomy.
[0135] Other Features
[0136] The gastric band of the present invention contains several
airspaces as a result of its design, and applicants have observed
that some precautions are required when implanting the gastric
band. In particular, airspaces within ring 22 typically contain
air, which is approximately 80% N.sub.2, and much of the ring is
encapsulated in a thin leak-proof silicone membrane (see FIGS. 2
and 4). Because this membrane permits CO.sub.2 to diffuse into the
ring about 20 times faster than the entrapped N.sub.2 can diffuse
out, significant swelling of the membrane may result when the
gastric ring is inserted into an abdomen expanded with CO.sub.2.
Once the N.sub.2 and CO.sub.2 pressures equilibrate, the swelling
resolves, typically in about three hours.
[0137] While the membrane is distended, however, there is a risk
that the membrane may be pierced, for example, by the sharp needles
employed to suture the fold of stomach tissue over the ring, or to
suture the antenna/controller pod in position. Applicants
accordingly have devised four solutions to address this issue: (1)
CO.sub.2 preconditioning; (2) CO.sub.2 packaging; (3) a valve
system; and (4) use of a less extensible membrane.
[0138] CO.sub.2 preconditioning refers to placing the gastric band
in a CO.sub.2-filled container for a specified duration, e.g., 3
hours, prior to implantation to permit the N.sub.2 and CO.sub.2
pressures to equilibrate prior to implantation. The gastric ring
may be sealed within sterile packaging prior to such
preconditioning. CO.sub.2 packaging refers to packaging the gastric
band in CO.sub.2-filled container during the manufacturing process,
so that no substantial swelling arises during the implantation
procedure. Use of a valve system would entail implementing a
pressure-relied valve on the membrane of the ring to avoid the
build up of overpressure within the device, while preventing bodily
fluids from ingressing into the device. Finally, the choice of a
different membrane material or thickness may be used to control the
swelling phenomena. During initial clinical testing of the device
the preconditioning option is expected to be used, although
CO.sub.2 packaging is contemplated as the most expedient solution
for commercial manufacture. Other gases than carbon dioxide may be
used to expand the abdomen, and such alternative preselected gases
likewise may be used to precondition the gastric ring of the
present invention.
[0139] As stated in the Overview portion of the present
application, the telemetrically-powered and controlled ring system
of the present invention has numerous applications apart from
gastric banding for the treatment of morbid obesity. For example,
the ring system of the present invention may advantageously be used
for the treatment of fecal incontinence, ileostomy, coleostomy,
gastro-esophageal reflux disease, urinary incontinence and
isolated-organ perfusion.
[0140] For treatment of fecal incontinence, the ring may be used
with little or no modifications. In addition, because the ring
adjustment procedure will be performed by the patient on at least a
daily basis, a portable user-friendly external control may be used.
In addition, because the ring will regularly be transitioned
between the closed and fully opened position, the patient microchip
card is unneeded. Instead, the fully closed position may be stored
in the memory of the implantable controller, and read by the
external remote at each use (subject to periodic change by the
physician).
[0141] A similarly modified device could be used by patients who
have undergone ileostomy or coleostomy, or disposed surrounding the
esophageal junction, to treat gastro-esophageal reflux disease.
[0142] For treatment of urinary incontinence, the ring may be
further modified to minimize the volume of the ring surrounding the
urethra by moving the actuator motor to a location elsewhere in the
lower abdomen or pelvis, and coupling the actuator to the motor via
a transmission cable.
[0143] The present invention also may be beneficially employed to
perform isolated-organ perfusion. The treatment of certain cancers
requires exposure to levels of chemotherapy agents that are too
high for systemic circulation. It has been suggested that one
solution to this problem is perform an open surgery procedure in
which blood flow to the cancerous organ is stopped and quiescient
blood replaced by circulation from an external source containing a
desired dose of drug. Individual or multiple rings of the present
invention may be used as valves to isolate the cancerous organ and
permit perfusion of the organ with high doses of drugs. Such
procedures could thus be performed on a repetitive basis without
surgery, thereby reducing the trauma and the risk to the patient
while improving patient outcomes.
[0144] Although particular embodiments of the present invention
have been described above in detail, it will be understood that
this description is merely for purposes of illustration. Further
variations will be apparent to one skilled in the art in light of
this disclosure and are intended to fall within the scope of the
appended claims.
* * * * *