U.S. patent application number 10/730646 was filed with the patent office on 2004-06-17 for method and apparatus for treating incontinence.
Invention is credited to Barnett, Robert W., Furness, John B., Hirst, George D., O'Connell, Helen E..
Application Number | 20040116773 10/730646 |
Document ID | / |
Family ID | 3816206 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040116773 |
Kind Code |
A1 |
Furness, John B. ; et
al. |
June 17, 2004 |
Method and apparatus for treating incontinence
Abstract
An improved method, system and arrangement for treatment of
urinary incontinence is disclosed, in which a portion of innervated
smooth muscle (2) is transplanted and disposed around the urethra
to provide a urethral sphincter (2). Electrical stimulation, by an
implanted stimulator (1), maintains continuous tone in the
sphincter. A remote controller (7) permits the sphincter (2) to be
allowed to relax, and hence permit urine to flow out of the
bladder.
Inventors: |
Furness, John B.; (Fitzroy,
AU) ; Barnett, Robert W.; (Thornbury, AU) ;
O'Connell, Helen E.; (Parkville, AU) ; Hirst, George
D.; (South Yarra, AU) |
Correspondence
Address: |
SACCO & ASSOCIATES, PA
P.O. BOX 30999
PALM BEACH GARDENS
FL
33420-0999
US
|
Family ID: |
3816206 |
Appl. No.: |
10/730646 |
Filed: |
December 8, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10730646 |
Dec 8, 2003 |
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10049071 |
Feb 4, 2002 |
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6659936 |
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10049071 |
Feb 4, 2002 |
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PCT/AU00/00925 |
Aug 4, 2000 |
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Current U.S.
Class: |
600/30 ;
607/41 |
Current CPC
Class: |
A61F 2/0036 20130101;
A61N 1/05 20130101; A61N 1/36007 20130101; A61F 2002/0894
20130101 |
Class at
Publication: |
600/030 ;
607/041 |
International
Class: |
A61F 002/02; A61N
001/36 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 1999 |
AU |
PQ 2026 |
Claims
What is claimed is:
1. An implantable sphincter stimulator configured for operatively
providing electrical stimulation to a surgically implanted
innervated smooth muscle sphincter so as to control the flow of a
bodily substance therethrough, the stimulator including: a stimulus
generating unit in electrical communication with a receiver, the
stimulus generating unit operatively configured to provide a first
predetermined electrical stimulation signal adapted to contract
said sphincter, and a second predetermined signal adapted to allow
said sphincter to relax, one of said predetermined signals being
selected in response to a control signal received at the receiver
from a remote controller.
2. A sphincter stimulator according to claim 1 wherein the
stimulation signal is such as to provide a continuous tone in said
sphincter.
3. A sphincter stimulator according to claim 2 wherein the
stimulation is pulsatile.
4. A sphincter stimulator according to claim 3 wherein the
stimulation signal is generally rectangular and symmetrical
biphasic.
5. A sphincter stimulator according to claim 4 wherein the
stimulation signal current is less than or equal to 30 mA.
6. A sphincter stimulator according to claim 3 wherein the
stimulation pulse frequency is in the range of 0.025 to 2.5 Hz.
7. A sphincter stimulator according to claim 3 wherein the
stimulation pulse has a width in the range of 0.05 to 0.20
milliseconds.
8. A sphincter stimulator according to claim 1 wherein the control
signal is communicated by RF, microwave, optically or
magnetically.
9. A sphincter stimulator according to claim 1 wherein the stimulus
generating unit includes a demodulator responsive to the received
signal for providing a modulated signal to a stimulus encoder which
in turn provides a signal to a stimulus driver which provides the
stimulation signal at selected ones of the stimulator outputs.
10. A sphincter stimulator according to claim 1 wherein after the
sphincter has relaxed, the stimulator includes means to supply the
first stimulation signal at a selected one of its outputs to
contract the sphincter when a predetermined signal to contract the
sphincter is not received by the receiver for a predetermined
period.
11. A sphincter stimulator according to claim 1 including a
transmitter for transmitting sphincter stimulator telemetry
information indicative of one or more parameters of the stimulator
for detection remotely.
12. A sphincter stimulator according to claim 11 wherein the
information is transmitted by the same communications means as the
control signal.
13. A sphincter stimulator according to claim 11 wherein the
parameters include one or more of the stimulation signal frequency,
current, width and/or shape, or received signal strength or battery
status.
14. A sphincter stimulator according to claim 11 wherein the
receiver is configured to accept a remotely generated sphincter
stimulator calibration signal and in response, the signal
processing unit selectively varies one or more of the output
properties of the sphincter stimulator.
15. A sphincter stimulator according to claim 14 wherein the
calibration signal is transmitted in response to received sphincter
stimulator telemetry information.
16. A sphincter stimulator according to claim 1 wherein the
stimulation generating unit is operatively connected to the
sphincter by one or more electrical leads, each having one or more
electrodes.
17. A sphincter stimulator according to claim 16 wherein the lead
includes three electrodes disposed in an epimysal configuration
about the sphincter.
18. A sphincter stimulator according to claim 16 wherein the lead
includes three electrodes disposed in a cuff configuration about
the sphincter.
19. A sphincter stimulator according to claim 16 wherein the lead
includes three electrodes disposed in a tripolar configuration
about the sphincter.
Description
FIELD OF THE INVENTION
[0001] This invention relates to prosthetic devices for the
treatment of urinary incontinence and, in particular, to prosthetic
devices employing transplanted tissue.
BACKGROUND OF THE INVENTION
[0002] The present invention is concerned with forms of
incontinence caused wholly or partly by inadequate sphincter
function. This may include forms of stress incontinence, urge
incontinence and total incontinence. The invention has been
developed initially for use in treating male incontinence and will
be described principally with respect to that application. However,
it will be appreciated by those skilled in the art that the
invention is also applicable for use in treating female
incontinence.
[0003] Incontinence is a major health problem, particularly with
the ageing population, for which there is no well-accepted medical
treatment. For females, surgically constructed slings are
increasingly being used for stress incontinence and with increasing
success. However, here is no low risk and reliably effective
treatment for moderate to severe male stress incontinence
particularly after treatment of prostate cancer. As the incidence
of prostate cancer is increasing, this is a growing health
issue.
[0004] The internal sphincter of the urethra consists of smooth
muscle cells interposed with elastic tissue and is located in the
proximal urethra. Its constant tone is crucial to maintaining
mechanical resistance in the proximal urethra sufficient to hold
back the passive pressure exerted by urine in the bladder. Weakness
in this area is a common cause of urinary incontinence, for example
after treatment for prostate cancer.
[0005] Prosthetic sphincter valves have been proposed in numerous
forms, including mechanical, hydraulic and electrical devices which
replace or supplement the defective damaged internal sphincter of
the urethra (e.g. PT 101841, SE 931516, GB 2266844, FR 2638964,
WO97/01309 and U.S. Pat. No. 4,619,245). Electrical stimulation of
the muscles of the sphincter has also been proposed (DE 29614895).
Other approaches have proposed the use of external or implanted
electrodes to stimulate existing sphincter function.
[0006] A variety of approaches have been proposed in relation to
the electrical stimulation of the muscles of the sphincter, most of
which are directed towards stimulating an existing sphincter and/or
muscles disposed about, for example, a bladder(DE 29614895).
[0007] Another group of prior art proposals for the treatment of
incontinence are directed towards the stimulation of sacral nerves
and the like. Such proposals again seek to use the existing muscle
structures. (U.S. Pat. No. 4,771,779, U.S. Pat. No. 4,703,775, U.S.
Pat. No. 4,607,639, U.S. Pat. No. 3,870,051, U.S. Pat. No.
4,688,575, U.S. Pat. No. 4,389,719 and U.S. Pat. No.
5,702,428).
[0008] Other stimulation means have been proposed, for example U.S.
Pat. No. 5,562,717, wherein stimulating electrodes are disposed on
the skin of a person to externally stimulate existing muscles to
control incontinence. This method is disadvantageous in that it
requires electrodes to be disposed in a predetermined location of
the person and be electrically connected to a power source
therefore not allowing complete freedom.
[0009] It has also been proposed to implant part of a small
skeletal muscle from the thigh around the patient's urethra, and
then to electrically stimulate the muscle to "retrain" it to
function as a replacement sphincter (New Scientist, 29 Jun. 1996).
However, this approach, even if successful, would require
relatively high levels of electrical stimulation to allow
sufficient contracture of the replacement sphincter.
[0010] It is an object of the present invention to provide an
improved prosthetic device for use in treating incontinence.
SUMMARY OF THE INVENTION
[0011] Broadly, the present invention utilises innervated smooth
muscle to provide an auxiliary sphincter. This is stimulated by a
suitable device in order to provide a functional sphincter in the
patient. As a consequence, the stimulator device can operate with
lower power consumption, and produce a superior sphincter
action.
[0012] According to a first aspect of the invention there is
provided an implantable sphincter stimulator configured for
operatively providing electrical stimulation to a surgically
implanted innervated smooth muscle sphincter disposed about a
urethra so as to control the flow of urine therethrough, the
stimulator including:
[0013] a stimulus generating unit in electrical communication with
a receiver, the stimulus generating unit operatively configured to
provide a first predetermined electrical stimulation signal adapted
to contract said sphincter, and a second predetermined signal
adapted to allow said sphincter to relax, one of said predetermined
signals being selected in response to a signal received at the
receiver from a remote controller.
[0014] In preferred embodiments, the stimulator applies the first
stimulation signal, unless a signal is received indicating that the
patient wishes to empty the bladder. The second stimulation signal
may be simply the absence of a stimulation, a lower level signal or
an alternative signal.
[0015] Preferably, the stimulation signal is one which will
maintain a continuous tone in the innervated sphincter. In other
preferred embodiments of the invention the stimulation signal is
pulsatile. Preferably, the stimulator provides multiple channel
pulse generation. Preferably also, the stimulation pulse frequency
is in the range of 0.25 to 2.5 Hz and having a width in the range
of 0.05 to 0.20 milliseconds.
[0016] Preferably the stimuli applied have a current less than or
equal to 30 mA.
[0017] More preferably, the stimulation signal is generally
rectangular and symmetrical biphasic, although alternative biphasic
pulses may be used.
[0018] Preferably, the sphincter stimulator includes a replaceable
or rechargeable battery power source, preferably one which is
in-situ rechargeable, for example inductively.
[0019] Preferably, the signal to the receiver is communicated by
microwave or radio means, optically or by magnetic energy and the
receiver respectively is a microwave, radio, photon or magnetic
energy receiver.
[0020] Preferably, the stimulus generating unit includes a
demodulator responsive to the received signal for providing a
modulated signal to a stimulus encoder which in turn provides a
signal to a stimulus driver. The stimulator preferably includes two
or more electrodes for operatively delivering the stimuli to the
sphincter. The stimuli may differ between electrodes, or may be the
same at each.
[0021] Preferably, after the sphincter has been relaxed, the
stimulator is adapted to supply the first stimulation signal to
contract the sphincter when a predetermined signal to contract the
sphincter is not received by the receiver after a predetermined
period.
[0022] Preferably, the sphincter stimulator includes a transmitter
for transmitting sphincter stimulator telemetry information
indicative of one or more parameters of the stimulator for
detection remotely. Preferably, the information is transmitted by
means of radio waves, microwaves, optically or by magnetic energy.
More preferably, the parameters include one or more of the
stimulation signal frequency, current, width and/or shape, and/or
of the received signal strength and battery status. Preferably, the
stimulus generating unit includes a processing device with
non-volatile memory.
[0023] Preferably, the receiver is configured to accept a remotely
generated sphincter stimulator calibration signal and in response,
the stimulus generation unit selectively varies one or more of the
stimulation signals. More preferably, the calibration signal is
transmitted in response to received sphincter stimulator telemetry
information, for example the telemetry signals from the
stimulator.
[0024] Preferably, the stimulator is in electrical communication
with the sphincter by at least one electrical lead having two or
more electrodes which are operatively implanted into the sphincter
at a predetermined location. More preferably, the lead includes
three electrodes disposed in an epimysal, cuff or tripolar
configuration about the sphincter.
[0025] Preferably, the smooth muscle is taken from the smooth
muscle of the bladder and transplanted about the urethra and having
its circulation intact. Alternatively, the muscle is venous smooth,
anococcygeus smooth muscle, terminal ileum transplanted as a
segment devoid of mucosa and having its circulation intact. A
further alternative is the dartos smooth muscle from the scrotum or
labia. In each case, the long axes of the muscle cells are disposed
substantially circumferentially about the sphincter. Depending upon
the muscle selected, the circulation may or may not be transplanted
intact. If the circulation is not transplanted intact, new vessels
will need to be regrown, or otherwise provided.
[0026] According to a second aspect of the invention there is
provided a system for use in treating bladder incontinence in a
person, the system including:
[0027] a portion of innervated smooth muscle tissue configured to
define a sphincter and implanted substantially circumferentially
about the urethra of the person;
[0028] an implanted sphincter stimulator arranged so as to allow
electrical stimuli to be applied to the sphincter; and
[0029] a non-implanted controller in communication with the
sphincter stimulator for selectively triggering the generation of
predetermined electrical stimulation signals to respectively
contract the sphincter or allow the sphincter to relax.
[0030] Preferably, the smooth muscle is in the form of a strip and
is generally rectangular. More preferably, the strip has dimensions
in the range from 4.5 cm to 7.5 cm by 1.25 cm to 2.25 cm. Also
preferable, the muscle is disposed substantially fully around the
urethra in a generally cylindrical arrangement such that the long
axes of the muscle cells are substantially circumferentially
aligned.
[0031] Preferably, the smooth muscle is selected from those
described above.
[0032] Preferably, the system includes a sphincter as described
above.
[0033] Preferably, the controller includes:
[0034] a transmitter;
[0035] means for generating a predetermined signal at the
transmitter;
[0036] a power source; and
[0037] actuation means for selectively generating a signal such
that on receipt of the signal, the sphincter stimulator provides
the stimulation signal at its output for contracting the sphincter
or allowing it to relax. The signals for selecting relaxation or
contracture may be different, or the same signal may trigger
alternation of states.
[0038] One form of the controller, particularly for use by a
physician, may include a receiver for receiving the sphincter
stimulator telemetry information signal from the sphincter
stimulator. Preferably, the signal is transmitted by radio waves,
microwaves, optically or by magnetic energy and receiver
respectively is a radio, microwave, photon or magnetic energy
receiver.
[0039] Preferably, the system includes a remote sphincter
stimulator programming unit for selectively programming the
sphincter stimulator to provide a predetermined output. Preferably,
one or more of the stimulation signal current, shape, frequency and
width is variable in response to the calibration signal provided by
the programming unit. More preferably, the programming unit
includes a transceiver for providing the programming signal to the
stimulator. The programming unit may conveniently be the physician
controller.
[0040] According to a third aspect of the invention there is
provided a method of using an implantable sphincter stimulator for
treating bladder incontinence, the method including the steps of
disposing an innervated smooth muscle sphincter about a urethra,
arranging one or more electrodes so as to allow stimulation of the
neural structures of said sphincter, said electrodes being
connected to the sphincter stimulator, so that post implantation, a
predetermined stimulation signal may be applied by a stimulus
generating unit to selectively contract the sphincter or allow it
to relax.
[0041] Preferably, the method includes the step of transmitting the
signal to the sphincter stimulator by radio signals, microwaves,
optically or by magnetic energy.
[0042] Preferably, three electrodes are arranged in the sphincter
in an epimysal, cuff or tripolar configuration.
[0043] Preferably, the sphincter is smooth muscle selected from
those previously described.
[0044] According to a fourth aspect of the invention there is
provided a method of treating incontinence including the steps
of:
[0045] disposing an innervated smooth muscle sphincter around a
urethra;
[0046] locating a plurality of electrodes in predetermined
locations in the sphincter and electrically connecting the
electrodes with an implanted sphincter stimulator; and
[0047] selectively actuating the sphincter stimulator to provide a
predetermined stimulation signal to either contract the sphincter
or allow it to relax in response to a remotely generated
signal.
[0048] According to another aspect of the invention there is
provided a method of surgically implanting a sphincter stimulator
in a system for treating urinary incontinence, including the steps
of:
[0049] implanting the innervated smooth muscle sphincter about the
urethra in a person;
[0050] implanting the electrodes into the sphincter at
predetermined locations; and
[0051] implanting the sphincter stimulator, the arrangement being
such that the electrodes are electrically connected to the
sphincter controller to permit stimulation signals from said
sphincter stimulator to stimulate the neural structures of said
smooth muscle.
[0052] Implanting in this context includes transplanting from the
same or another person, or the use of externally prepared smooth
muscle tissue. In each aspect, it is preferred that the implanted
sphincter function so as to substantially prevent leakage of urine
when contracted. In general, the main function of the innervated
muscle prosthesis is to augment function in the internal sphincter.
It should not be used to override any natural sphincter function
that may be preserved. The sphincteric pressure exerted by the
prosthesis should be sufficient to restore the net sphincteric
resistance to its normal level of operation. Unnecessarily high
pressure would not only be wasteful of internal stimulator energy
but could also cause dangerous overfilling of the bladder. On the
other hand, the pressure must be sufficiently high to prevent the
leakage of urine.
[0053] The smooth muscle tissue may be selected from those
described above, or any other suitable smooth muscle tissue. It
will be appreciated by those skilled in the art that other types of
smooth muscle may potentially be employed as the implantable
sphincter including alpha-adrenergic excitatory innervation,
cholinergenic excitatory or, inter alia, circular intestinal
muscle.
[0054] One advantage of using smooth muscle tissue is that it
physiologically performs a sphincteric-like function and the muscle
layer should be able to be transplanted whilst maintaining its
innervation, or allowing for its reinnervation, and blood supply.
Moreover, smooth muscle of the types described is readily
reinnervated by sympathetic nerves should the existing innervation
be damaged during surgery. Reinnervation may take some time, for
example, two to three weeks, after surgery.
[0055] Another advantages associated with the use of an innervated
smooth muscle sphincter in accordance with the present invention is
that in smooth muscle, a long-lasting contracture (2-3 seconds)
results from a single neural stimulation. Accordingly, only a low
frequency of stimulation is required to produce a tetanic
contraction especially where it is moderated by neurotransmitter
release.
[0056] The tension generated per unit cross-sectional area of
smooth muscle is greater than for skeletal muscle. Smooth muscle
generates tension over a wide length/tension relationship, that is,
it continues to generate tension even when partially contracted.
Smooth muscle is able to maintain high tension with relatively low
energy expenditure. Smooth muscle tissue generally displays a
persistent generation of tone during low frequency repetitive nerve
stimulation.
[0057] A further advantage of the use of smooth muscle according to
the present invention is that low frequency nerve stimulation
causes the release of a chemical transmitter. Stimulating the
nerves within smooth muscle invariably triggers a contraction
because the neurotransmitter interacts with a receptor. The
activated transmitter/receptor complex then activates a second
messenger pathway and releases calcium ions from internal stores.
It is relevant that calcium is the final trigger in the contraction
of both skeletal, smooth or cardiac muscle. When stores release
calcium they do so for extended periods of time, typically in the
order of several seconds. Therefore, if the exciting pathway is
triggered repeatedly at low frequencies a sustained rise in calcium
occurs and the smooth muscle develops a contracture. That is, it
does not relax between stimuli. In some smooth muscles, a few
stimuli delivered every two seconds, for example, will lead to a
sustained contraction.
[0058] An alternative way to excite smooth muscle is to stimulate
it directly which produces quite long lasting contractions but only
on application of very high stimulating voltages. Nerves have low
thresholds for activation, compared with muscles, and this,
together with the low frequencies of activation required, means
that stimulus spread will be avoided. Importantly, an electrical
device can reasonably be expected to survive untouched for many
years with such low usage demands.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] A preferred embodiment of the invention will now be
described, by way of example only, with reference to the
accompanying drawings in which:
[0060] FIG. 1 is a schematic illustration of a system for treating
incontinence according to the invention,
[0061] FIG. 2 schematically illustrates the implanted sphincter
stimulator of FIG. 1;
[0062] FIG. 3 schematically illustrates external and implanted
parts of the system of FIG. 1;
[0063] FIG. 4 illustrates a sphincter stimulator programming unit
and sphincter stimulator of the system of FIG. 1;
[0064] FIG. 5 is an alternative schematic illustration of the
system of FIG. 1 showing a preferred configuration of electrodes;
and
[0065] FIG. 6 is an enlarged view of the electrode configuration of
FIG. 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0066] Referring in general to FIGS. 1 to 6, there is illustrated
an implantable sphincter stimulator 1 for selectively providing
electrical stimulation to an innervated smooth muscle sphincter 2
disposed about a urethra 3 for controlling the flow of urine.
[0067] Stimulator 1 includes a signal processing unit 4 in
electrical communication with a receiver 5. Signal processing unit
4 is configured to provide a predetermined electrical stimulation
signal at a first output 6 of stimulator 1 in response to a signal
generated remotely by controller 7 and applied at receiver 5 such
that processing unit 4 selectively provides the stimulation signal
to either contract sphincter 2 to substantially block the flow of
urine along the urethra 3 or to allow sphincter 2 to relax and
allow urine to flow.
[0068] Referring to FIG. 2 particularly, signal processing unit 4
includes a demodulator 8 responsive to the signal received at
receiver 5 for providing a modulated signal to a stimulus encoder 9
which in turn provides a signal to a stimulus driver 10 which
provides the stimulated signal at sphincter stimulator output
6.
[0069] Once sphincter 2 is allowed to relax, processing unit 4
includes means to supply a stimulation signal at output 6 to
contract sphincter 2 when a predetermined signal to contract the
sphincter is not received by signal processing unit 4 via receiver
5 for a predetermined time period. In the preferred implementation,
the processing unit 4 provides stimuli adapted to contract the
sphincter unless a signal is received, in response to which the
stimuli is turned off, and the sphincter relaxes.
[0070] The signal is communicated to sphincter stimulator 1 by
means of radio frequency waves and receiver 5 is an RF receiver. If
the casing of the stimulator is made of titanium, and the receiver
is inside, then a frequency of 8-10 kHz is preferred. If the casing
is made of silicone rubber or the like, then 8-10 MHz is
preferred.
[0071] In other embodiments of the invention, the signal may be
communicated optically in the range 630 nm to 1400 nm to sphincter
stimulator 1 and receiver 5 is a photon detector in the form of a
PMT, photo-diode or other suitable detector.
[0072] In yet other embodiments of the invention, the signal is
communicated to sphincter stimulator 1 by microwave means and
receiver 5 is a microwave receiver. In such embodiments, the
microwave signal has a frequency in the range of 0.9 to 2.5 GHz.
Alternatively, the signal is communicated to sphincter stimulator 1
by magnetic means and receiver 5 is a magnetic energy receiver. Any
other suitable communication arrangement may be used.
[0073] As is best illustrated in FIG. 3, controller 7 includes the
RF transmitter which is driven by a means for generating the
control signal. Controller 7 further includes actuation means for
selectively generating the control signal at transmitter 11.
[0074] Part of transmitter 11 is also a receiver for receiving an
information signal indicative of at least one parameter of the
sphincter stimulator and provided by the sphincter stimulator. The
telemetry information signal is transmitted to the controller by
means of a transmitter disposed within receiver 5. In embodiments
of the invention where microwaves are employed to communicate
either the control signal or telemetry information signal,
transceiver 11 of controller 7 is configured to transmit and
receive microwave radiation. In embodiments where the control
signal is transmitted optically, transceiver 11 includes a photon
detector in the form of a PMT or solid state device and a light
source having a predetermined output. In embodiments of the
invention where the control signal and the sphincter stimulator
information signal are transmitted by magnetic energy, the
transmitter receiver 5 functions as a passive proximity card and
controller 7 functions as the active proximity card reader.
[0075] FIG. 2 illustrates a stimulation signal in the form of a
pulse. The pulse is generally rectangular and symmetrically
biphasic. In other embodiments of the invention, not illustrated,
sphincter stimulator 1 provides multiple channel pulse generation
at output 6. The stimulation signal is selected so as to provide a
substantially continuous tone in the sphincter.
[0076] The stimulation signal provided at output 6 has a
substantially constant current less that or equal to 30 mA, and
preferably of the order of 15 mA.
[0077] The stimulation pulse frequency provided to sphincter 1 by
output 6 is in the range of 0.25 Hz to 2.5 Hz and is preferably 2
Hz. The stimulation pulse width is in the range of 0.05 ms to 0.2
ms and is preferably 0.15 ms. It should be noted that the device is
current regulated, and accordingly the stimulation voltage will
vary with the resistance of the muscle tissue between the
electrodes. Typical values for the voltage are between 0.2 and 7
volts.
[0078] It should be noted, however, that these parameters are
variable and are configured for each person.
[0079] Preferably, the smooth muscle is taken from the smooth
muscle of the bladder and transplanted about the urethra and having
its circulation intact. Alternatively, the muscle may be venous
smooth, anococcygeus smooth muscle, terminal ileum transplanted as
a segment devoid of mucosa and having its circulation intact. A
further alternative is the dartos smooth muscle from the scrotum or
labia. Any other suitable muscle may be employed. In each case, the
long axes of the muscle cells are disposed substantially
circumferentially about the sphincter.
[0080] The muscle is generally in the form of a rectangular strip
such that the long axes of the muscle cells are disposed
substantially lengthwise along the strip. The muscle is then
disposed substantially fully around the urethra in a generally
cylindrical arrangement such that the long axes of the muscle cells
are substantially circumferencially disposed about the urethra.
Preferably, the strip is completely disposed around the
urethra.
[0081] The muscle strip has dimensions 6 cm by 2 cm and is
preferably provided in the range from 4.5 cm to 7.5 cm by 1.25 cm
to 2.25 cm.
[0082] The stimulation signal is provided at output 6 of sphincter
stimulator 1 is supplied to sphincter 2 by an electrode implanted
into the sphincter at a predetermined location and an electrical
lead 16 being disposed intermediate. As is best illustrated in FIG.
6, lead 16 includes three electrodes disposed in a tripolar
configuration about sphincter 2 and having means to electrically
connect to lead 16. In other embodiments of the invention, the
three electrodes are disposed in a cuff or epimysal configuration
about the sphincter.
[0083] Electrode leads may extend between the pulse generator and
the electrodes, allowing some "slackness" in their length to
account for normal body movements.
[0084] As is best illustrated in FIGS. 5 and 6, the configuration
of the electrodes are disposed in a tripolar configuration. Simple
tripolar electrodes are the least expensive alternative, are
relatively easy to implant and can be used to stimulate the
transplanted smooth muscle. Their exposed metallic surfaces usually
consist of a cathode aligned between two anodes.
[0085] In the epimysial configuration, the electrodes are sutured
directly onto the surface of a muscle. These electrodes are
implemented when stimulation of a motor nerve trunk is impractical,
however, this is not necessarily always the case.
[0086] In the cuff electrode configurations are employed in
alternative embodiments and are contained within an insulating
sheath substantially circumferentially around the circumference of
the transplanted sphincter. They are capable of stimulating the
embedded nerve fibres maximally while keeping the stimulus field
local to the transplant.
[0087] In other embodiments of the invention, not illustrated, the
sphincter stimulator includes a second output such that one of the
sphincter stimulator outputs provides a signal to contract the
sphincter and the other output provides a stimulation signal to
allow the sphincter to relax or contract to a lesser extent. In
this embodiment, each of the first and second outputs of the
sphincter stimulator each include a lead having three outputs in a
tripolar configuration about the sphincter. In yet other
embodiments, the first and second outputs each include a lead
having three electrodes disposed in a cuff or epimysal
configuration about the sphincter.
[0088] It will be appreciated that in normal use, only two of the
three electrodes will be used to deliver stimuli. The third
electrode is provided as a spare, in the event that one of the
electrodes ceases to function. However, it is contemplated that the
present invention could use a more complicated set of stimuli, or
more electrodes.
[0089] Sphincter stimulator 1 includes a replaceable battery power
source 17, not illustrated in FIG. 2. In one implementation,
battery 17 is in electrical communication with signal processing
unit 4 such that the control signal provided by controller 7 to
sphincter stimulator 1 inductively provides energy to recharge the
battery. In another implementation, in the case of radio frequency
transceiving between the and sphincter stimulators, the signal is
provided by modulating the RF signal such that the signal
processing unit extracts the control signal and provides the
battery with remaining power from the RF signal.
[0090] As is best illustrated in FIG. 4, RF transceiver 5 of
stimulator 1 is communicable with a third output of processing unit
4 for transmitting sphincter stimulator telemetry information
indicative of one or more the parameters of the sphincter
stimulator for remote detection. The information is transmitted by
radio frequency signals, however, in other embodiments of the
invention the sphincter stimulator information is transmitted by
microwave means, optical means or by magnetic energy. The sphincter
stimulator information signal includes information regarding
parameters such as stimulation signal-frequency, current, width
and/or shape, and received signal strength and battery status. This
is useful for use in a controller intended for use by
physicians.
[0091] A remote sphincter stimulator programming unit 13 is adapted
to receive the sphincter stimulator information provided by
receiver 5. The sphincter stimulator programming unit includes a
transceiver 14 for providing a calibration signal to stimulator 1
which, in response, selectively varies one or more of the output
properties of stimulator 1. The calibration signal is preferably
transmitted in response to receiving the sphincter stimulator
telemetry information. The calibration signal includes coding to
selectively vary the output current, shape, frequency and/or width.
Conveniently, the remote sphincter stimulator programming unit is
integrated into the physician controller.
[0092] The preferred embodiments of the invention also provide a
method of treating urinary incontinence in a person including the
steps of disposing the implanted smooth muscle sphincter
substantially around a urethra, locating a plurality of electrodes
in predetermined locations in the sphincter and electrically
connecting them with an implanted sphincter stimulator as
hereinbefore described.
[0093] The sphincter stimulator is then selectively actuated on
receipt of the control signal to provide the predetermined
stimulation signal to either contract the sphincter or allow it to
relax. The method includes providing the stimulation signal to
contract the urethra or allow it to relax from output 6 of
sphincter stimulator 1. In other embodiments of the invention,
however, the stimulation signal to contract the sphincter about the
urethra is provided by a separate output of sphincter stimulator 1
to that which provides a stimulation signal to allow the urethra to
relax.
[0094] There is also provided a method of surgically implanting a
sphincter stimulator system as hereinbefore described in a person
for treating incontinence, the method including the steps of
implanting the smooth muscle sphincter substantially about the
urethra in a person, implanting the sphincter stimulator in the
person proximal to the implanted sphincter and implanting
electrodes into the sphincter at predetermined locations and
electrically connecting the sphincter stimulator with the smooth
muscle sphincter.
[0095] Other preferred embodiments provide a stimulus system
including circuit means defining a single channel electrical pulse
generator, power supply means, a control circuit to allow a
transplanted sphincter to relax, a separate control circuit to
adjust pulse parameters, two or more stimulus electrodes, and leads
connecting the stimulator to the electrodes.
[0096] The prosthetic sphincter includes a sheath of innervated or
reinnervatable muscle tissue taken from the selected muscle and
transplanted around the urethra. In one embodiment, a segment of
distal small intestine, 2-3 cm long, on a vascular pedicle is
isolated and the remaining intestine is rejoined by end to end
anastomosis. The isolated segment is opened along its
antimesenteric border and the mucosa is dissected away.
[0097] The isolated segment is drawn down to the neck of the
bladder. It is then taken around the bladder neck, so that the
circular muscle is disposed substantially circumferentially with
respect to the neck, and the cut antimesenteric borders are sewn
together to create a close fit around the neck of the bladder. If
necessary, the circumferential length is reduced to create a close
fit. The newly created and vascularised sphincter is secured in
place by sewing it to the superficial connective tissue of the
bladder neck. A stimulating electrode assembly is sewn to the
transplanted intestine, with the axis of the electrode assembly at
right angles to the circular muscle, adjacent to the entry of the
vessels from the vascular pedicle. The anchoring ligatures
penetrate the sphincter and are secured to the underlying bladder
neck.
[0098] In an alternative embodiment, the sphincter augmentation is
made by dissecting the anococcygeus muscles from their spinal
insertions, and drawing the freed muscle around the bladder neck.
The sphincter may also be created from a section of muscular vein,
venous smooth muscle, the terminal ilium and transplanted as a
segment devoid of mucosa and having its circulation intact, or the
dartos smooth muscle from the scrotum or labia.
[0099] The stimulus pulse generator transfers electrical pulses to
the electrodes and these pulses are converted into action
potentials in the nerves transplanted with the muscle sphincter or
in the nerves which re-innervate the sphincter after surgery.
[0100] All implanted circuitry is preferably sealed and encased in
a biologically inert material such as a biocompatible silicone
material. The metallic electrodes and leads are preferably of
Platinum-Iridium alloy. The connecting wires are preferably
insulated with a silicone coating and lead to an implanted control
unit placed between the abdominal muscle and skin.
[0101] The stimulator is required to maintain continuous tone in
the transplanted sphincter sufficient to hold urine in the bladder
without leakage by continuous stimulation. To release urine, an
external control unit using, for example, a radio frequency signal
will turn off the internal unit to halt the stimulation of the
sphincter, and is shown schematically in FIG. 3.
[0102] Alternative embodiments of the invention employ microwave or
optical means, for example, in the form of infra-red radiation, to
communicate the control signal to the sphincter stimulator, and the
sphincter stimulator includes a corresponding receiver at or near
the skin of the person.
[0103] The person would hold the external device adjacent the skin
over the implant (and push an actuation button) to allow the
transplanted sphincter to relax and urine to flow. After bladder
emptying, the patient would then push the button again to resume
sphincteric pressure. As described, if the user forgets to push the
button to close the sphincter, the stimulator could be programmed
to resume operation automatically after a given time.
[0104] The advantages of this system are twofold. Firstly, the
patient does not need to hold the external control unit against
their skin for the whole period of bladder emptying. They simply
initiate the process and can then put the unit aside if desired.
The second advantage is that such a system allows the stimulator
circuitry to be adjusted externally.
[0105] In embodiments where the signal is communicated
magnetically, a permanent magnet is placed on the surface of the
skin directly over the location of the implanted control circuit.
The circuit is designed to detect the presence of the magnetic
field and shut off the stimulation accordingly. To empty the
bladder, therefore, the person simply places a magnet over the
implant for the time period required to empty the bladder. A small
permanent magnet is a convenient item to carry around and requires
no batteries. One disadvantage of such a system is that a magnetic
detector needs to be added to the implanted device and this, in
turn, requires more power from the internal batteries.
[0106] It is envisaged that the requirements of the stimulator may
change, both post-operatively and with alteration of the preserved
sphincteric resistance as the person ages. Access to the implanted
device via surgery for the purpose of hardware adjustment is, of
course, undesirable. Therefore, adjustment of the stimulus
parameters via an external radio link to the sphincter stimulator
programming unit 13 is a preferred feature of the system.
[0107] It will be appreciated that various modifications and
alterations may be made to the system described above without
departing from the scope and spirit of the invention.
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