U.S. patent application number 13/200840 was filed with the patent office on 2014-09-11 for transcutaneous telemetry of cerebrospinal fluid shunt programmable-valve pressure using near-infrared (nir) light.
The applicant listed for this patent is Erich W. Wolf, II. Invention is credited to Erich W. Wolf, II.
Application Number | 20140257166 13/200840 |
Document ID | / |
Family ID | 40939516 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140257166 |
Kind Code |
A9 |
Wolf, II; Erich W. |
September 11, 2014 |
Transcutaneous telemetry of cerebrospinal fluid shunt
programmable-valve pressure using near-infrared (NIR) light
Abstract
An improvement for a programmable valve system of the type
implanted in a patient and used to divert cerebrospinal fluid (CSF)
from an intraventricular space to a terminus such as the peritoneal
cavity. Such system includes means for establishing a flow path for
the CSF to the terminus, which flow path includes a normally closed
valve and means for adjusting the opening pressure of the valve in
order to regulate the quantity of CSF diverted. The improvement
enables an operator to be apprised of the actual opening pressure
setting of the valve. A sensor is implantable at the patient and
responds to the actual opening pressure setting, by generating an
NIR telemetry signal indicative of the actual setting. This signal
is transcutaneously transmitted through the skin of the patient to
an external point. The telemetry signal is processed to produce
observer intelligible data indicating the opening pressure setting
of the valve.
Inventors: |
Wolf, II; Erich W.; (Lake
Charles, LA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Wolf, II; Erich W. |
Lake Charles |
LA |
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20120029414 A1 |
February 2, 2012 |
|
|
Family ID: |
40939516 |
Appl. No.: |
13/200840 |
Filed: |
October 3, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12321332 |
Jan 20, 2009 |
8057422 |
|
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13200840 |
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|
11067497 |
Feb 25, 2005 |
7485105 |
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12321332 |
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60547691 |
Feb 25, 2004 |
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60577807 |
Jun 8, 2004 |
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60582337 |
Jun 23, 2004 |
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Current U.S.
Class: |
604/9 |
Current CPC
Class: |
H04B 10/1141 20130101;
A61B 5/0031 20130101; A61M 27/006 20130101; A61M 2205/3313
20130101; A61B 5/031 20130101; A61M 2205/3523 20130101; A61F
2250/0001 20130101; A61M 2205/3592 20130101; H04B 10/806
20130101 |
Class at
Publication: |
604/9 |
International
Class: |
A61M 1/00 20060101
A61M001/00 |
Claims
1. A system for retrieving the biometric pressure data from a
programmable valve implanted in an organism comprising: an
intracorporeal device sealed within the organism; an extracorporeal
device outside the organism; a freespace optical data channel
established between the intracorporeal device and the
extracorporeal device for communication of the biometric pressure
data; a freespace electromagnetic power transmission channel
established from the extracorporeal device to the intracorporeal
device for transmission of power; and a freespace mechanical power
transmission channel established from the extracorporeal device to
the intracorporeal device for manipulation of a position of the
intracorporeal device.
2. The system of claim 1 wherein the freespace optical data channel
is bidirectional.
3. The system of claim 1 wherein the freespace optical data channel
is in a wavelength range between 800 nm and 1000 nm.
4. The system of claim 1 wherein the intracorporeal device is
powered only upon receipt of a transmission of power from the
electromagnetic power transmission channel.
5. The system of claim 4 wherein a light emitting diode on the
extracorporeal device illuminates when the intracorporeal device
receives power.
6. The system of claim 1 wherein the extracorporeal device includes
a processor for operating on the transmitted near infrared
form.
7. The system of claim 6 further comprising a memory means, in
communication with the processor, for storage of a data set related
to the angular position of the valve.
8. The system of claim 7 wherein the processor is further
programmed to conduct signal processing on the data set.
9. The system of claim 1 wherein the extracorporeal device further
comprises a coupling module, an analysis module and an external
mechanical programmer.
10. The system of claim 9 wherein the coupling module further
comprises: an optical receiver coupled to the freespace optical
data channel and; a power transmitter coupled to the
electromagnetic power transmission channel.
11. The system of claim 9 wherein the external mechanical
programmer further comprises: a driver magnet coupled to the
freespace mechanical power transmission channel.
12. The system of claim 9 wherein the analysis module further
comprises: an optical receiver coupled to the freespace optical
data channel; a decoder coupled to the optical receiver; and a
processor connected to the decoder programmed to interpret the
biometric data.
13. The system of claim 9 wherein the power transmitter further
includes: a power signal conditioner; and a transformer connected
to the power signal conditioner and to the power transmitter.
14. The system of claim 1 wherein the intracorporeal device further
includes an encoding system for generating a signal related to an
angular position of the valve data.
15. The system of claim 14 wherein the encoding system further
comprises: an encoder disk; an optical source adjacent to the
encoder disk; an optical receiver in communication with the optical
source for generating an encoded signal related to the angular
position of the encoder disk; and an optical transmitter coupled to
the freespace optical data channel adapted to transmit the encoded
signal.
16. The system of claim 14 wherein the encoder disk further
comprises: an optically opaque disk having an encoder pattern and a
reference pattern; a light source adjacent to the optically opaque
disk and adapted to transmit light through the encoder pattern and
the reference pattern; a first reference array adjacent the encoder
pattern adapted to receive light through the encoder pattern and
generate an angular position signal indicative of the angular
position of the encoder disk; a second reference array adjacent the
reference pattern adapted to receive light through the reference
pattern and generate a data valid signal indicative of the validity
of the angular position signal.
17. A method of moving an implanted device in an organism
comprising the steps of: activating the implanted device through an
inductively coupled power source; electromagnetically creating an
altered position of the device; and deriving an optical data signal
from the altered position; and transmitting it out of the
organism.
18. The method of claim 17 wherein the step of activating comprises
the further steps of: generating electromagnetic power signal by an
extracorporeal device; and receiving of the electromagnetic power
signal by the implanted device.
19. The method of claim 17 wherein the step of collecting comprises
the further steps of: generating a data signal in response to the
position of a valve coupled to the implanted device; and
transforming the data signal into the near infrared signal.
20. The method of claim 17 wherein the step of electromagnetically
creating further comprises: rotating a driver magnet above the
implanted device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation claiming priority benefit
from U.S. patent application Ser. No. 12/321,332 entitled
"Transcutaneous Telemetry Of Cerebrospinal Fluid Shunt
Programmable-Valve Pressure Using Near-Infrared (NIR) Light" filed
Jan. 20, 2009 which claims priority from U.S. patent application
Ser. No. 11/067,497, now U.S. Pat. No. 7,485,105 issued Feb. 3,
2009, which claims priority from U.S. Provisional Applications
60/547,691 filed Feb. 25, 2004; 60/577,807 filed Jun. 8, 2004; and
60/582,337 filed Jun. 23, 2004.
FIELD OF INVENTION
[0002] This invention relates generally to transcutaneous telemetry
with an implantable biomedical device, and more specifically
relates to a system which allows transcutaneous telemetry of a
programmed valve opening pressure via near-infrared (NIR)
light.
BACKGROUND OF THE INVENTION
[0003] Fluidic shunts are commonly employed for the diversion of
cerebrospinal fluid from the cranial intraventricular space to a
terminus such as the peritoneal cavity in the treatment of
hydrocephalus. The quantity of cerebrospinal fluid (CSF) diverted
by the shunt may be altered by adjusting the opening pressure of a
normally closed integral valve. Several valve designs (e.g.
Codman-Hakim.RTM. valve, Medtronic Strata.RTM. valve) allow
transcutaneous adjustment, or programmability, of the opening
pressure via a transcutaneously applied magnetic field.
[0004] The programmed valve pressure is dependent upon the position
of the external programmer relative to the implanted valve. Because
the valve is implanted beneath the skin, the exact orientation of
the valve is not always apparent. Malpositioning of the programmer
can introduce errors into the programming process and result in
erroneous pressures being programmed. Therefore, it is desirable to
be able to confirm the actual programmed pressure after
reprogramming or as clinical conditions warrant. By "actual"
programmed pressure is meant the de facto pressure which has been
set for opening of the valve as opposed to the pressure which may
be assumed to have been set as a result of the operator's manual
adjustment.
[0005] While the Medtronic Strata.RTM. valve provides a
transcutaneous means of magnetically indicating the valve pressure
setting, the Codman-Hakim valve requires the use of an x-ray to
determine the valve setting. The use of x-ray to determine valve
pressure is undesirable as it is costly, time-consuming, and
exposes the patient to ionizing radiation.
SUMMARY OF INVENTION
[0006] The invention disclosed herein provides an improvement
pertinent to existing programmable valve systems which allows
transcutaneous telemetry of programmed valve opening pressure via
near-infrared (NIR) light. NIR light easily penetrates body tissues
such as the scalp, and the light beam may be modulated to encode
data for transcutaneous transmission. The actual valve pressure
setting is determined by an attached cam. An optical disc coaxially
mounted with the cam optically encodes the valve position and these
data are transmitted extracorporally via NIR light.
[0007] Light in the near-infrared spectrum is easily transmitted
through the skin and is detected by an external sensor head and
associated electronics. Indefinite longevity and small size is
attained in the implant by not incorporating a power source within
the module. Instead, power is derived inductively through
rectification of a transcutaneously-applied high-frequency
alternating electromagnetic field which is generated by a power
source within the external coupling module, in concept much like a
conventional electrical transformer. The extracorporeal components
of the system calculate the actual valve opening pressure
setting.
[0008] The present invention overcomes the aforementioned
disadvantages of existing technologies by providing a means for
telemetric conveyance of physiological data via transcutaneous
projection of a near infrared light beam. The use of this technique
for telemetry of intracranial pressure and other applications is
set forth in U.S. Pat. No. 7,435,229 to Wolf filed Feb. 24, 2005.
The entire disclosure of that application is hereby incorporated
herein by reference.
[0009] The NIR spectrum is defined as 750-2500 nm. Choice of the
preferred NIR wavelength for transcutaneous telemetry pursuant to
the present invention is dependent upon the absorption coefficients
of the intervening tissues. The absorption by melanosomes dominates
over the visible and near-infrared spectra to about 1100 nm, above
which free water begins to dominate. Absorption by the dermis
decreased monotonically over the 700-1000 nm range. Whole blood has
a minimum absorption at about 700 nm but remains low over the
700-1000 nm range. The nadir in the composite absorption spectrum
therefore lies in the 800-1000 nm range.
[0010] The actual wavelength utilized is therefore dictated by-the
optimal spectral range (as above) and the availability of suitable
semiconductor emitters. Several suitable wavelengths may include,
but are not limited to: 760 nm, 765 nm, 780 nm, 785 nm, 790 nm, 800
nm, 805 nm, 808 nm, 810 nm, 820 nm, 830 nm, 840 nm, 850 nm, 870 nm,
880 nm, 900 nm, 904 nm, 905 nm, 915 nm, 920 nm, 940 nm, 950 nm, 970
nm, and 980 nm. Wavelengths outside this range may be used but will
be subject to greater attenuation by the intervening tissues.
BRIEF DESCRIPTION OF DRAWINGS
[0011] The invention is diagrammatically illustrated, by way of
Example, in the drawings appended hereto, in which:
[0012] FIG. 1 is a simplified longitudinal cross sectional diagram
illustrating how the sensor may be implanted in a typical use with
a patient;
[0013] FIG. 2 is a schematic diagram, partially in block form,
illustrating an overall system in accordance with the
invention;
[0014] FIG. 3 is an electrical schematic diagram of the valve
pressure transducer and associated components; and
[0015] FIG. 4 is a schematic block diagram of the valve position
sensor components which are external to the patient.
[0016] FIG. 5 is a non-schematic diagram of the relationship and
positioning of the optical encoder and magnetic flux coupling of
the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] The system of the present invention as shown in the
simplified crosssectional view of FIG. 1 includes an extracorporeal
sensor head 70 which provides an interface to a human operator and
which telemeters with an implanted component 14. The latter is
integrated into the shunt-valve housing, detects the actual valve
setting, and telemeters these data to the extracorporeal sensor
head 70. The implanted component 14 may derive its power via
inductive coupling from the extracorporeal sensor head 70.
[0018] In a typical in vivo implementation a hollow ventricular
catheter 3 is placed surgically into a cerebrospinal fluid (CSF)
filled ventricle 2 of the brain 6 of the patient. The CSF is
communicated via the ventricular catheter 3 to the implanted
component 14 where its flow is controlled by controllable pressure
valve 18 (FIG. 2). The normally closed valve opening pressure
setting is controlled by an attached cam which is mounted on a
rotatable axis. An optical disc on that axis acts with other
elements to encode the valve position, data for which is
transmitted extracorporally through skin 20 via NIR light to sensor
head 70. Depending on valve position, the CSF may exit the
implanted sensor 14 and passes, via distal catheter 4, ultimately
to the peritoneal cavity of the abdomen (not shown) or other
appropriate point. The implanted sensor 14 is installed superficial
to, or embedded within the skull 5.
[0019] FIG. 2 depicts a schematic block diagram of a preferred
embodiment of the ICP Valve transducer system. FIG. 5 shows a
non-schematic diagram of the relationship and positioning of the
optical encoder disk and magnetic flux coupling. External
programmer 16 is an extracorporeal device which is used to set the
opening pressure of a programmable pressure valve 18 which is
implanted beneath the skin (scalp) 20 of the patient. The opening
pressure of normally closed valve 18 dictates the maximum pressure
gradient between the cerebrospinal fluid compartment which is
connected to inlet 22 to valve 18, and the outflow for which is via
outlet 24. The valve 18 pressure setting is dependent upon the
position of a cam which rotates around the valve's mechanical axis
26.
[0020] The external programmer 16 is able to modify the rotational
position of the valve 18 and mechanical axis 26 via magnetic flux
coupling 28 between an external magnet 30 and a magnet 32 fixedly
attached to the mechanical axis 26 of the valve mechanism. The
technology referenced by items 16 through 32 is described in the
prior art.
[0021] In prior art valves exemplified by valve 18, detents within
the valve mechanism define specific rotational angles in which the
valve mechanism axis 26 may remain in a static position. In the
preferred embodiment of the current invention, an optical encoder
disc 34 secured to axis 26 is an optically opaque disc with
radially oriented perforations (or optically transparent windows)
which encode binary numerals. Each specific static rotational angle
which may be assumed by the valve mechanism axis 26 has a
corresponding unique encoded binary numeral, n. An NIR light beam
36 transilluminates the optical encoder disc 34 such that the
binary encoded numeral, n, may be detected by photodetector array
38. In the preferred embodiment, these encoded numerals are
arranged sequentially around the disc 34 ranging from 1 to `N`
where N is the total number of discrete static positions of the
valve mechanism axis 26. A valid encoded numeral, n, is detected by
the photodetector array 38 only during transillumination of the
encoder disc 34 by NIR light beam 36. A "data valid" command is
generated by logical OR of each of the bits of the binary encoded
numeral, n, or by using a single separate photodetector with an
additional optical window at each discrete static position of the
valve mechanism axis 26. The "data valid" signal provides a `load`
command 40 to a latch 42 which stores the encoded binary numeral,
n.
[0022] The encoded binary numeral, n, is used as the divisor for a
divide-by-n counter 44. A crystal oscillator 46 provides a stable
reference frequency 48, f.sub.in, which is divided by the divisor
ratio, n. Therefore, the output frequency 50, f.sub.out, is
uniquely dependent upon the valve mechanism axis 26 position, and
hence the pressure to valve 18. The near infrared emitter 52 is
driven at the output frequency 50. The infrared beam 54 is passed
through a beam-splitter mirror 56 such that a portion of the
infrared light beam 36 is used to transilluminate the optical
encoder disc 34. The remainder of beam 54 travels through the skin
20 to become the transcutaneous NIR beam 58. The transcutaneous
beam 58 is detected by a photodetector 82 within sensor head and
processing electronics 62 after passing through a narrow bandpass
filter 64. The narrow bandpass filter 64 excludes ambient light at
wavelengths other than that expected from the NIR emitter 52. The
frequency of the photodetector 82 output is measured at 63 and is
used to index a look-up table 60 which correlates the modulation
frequency 50 with the actual valve pressure setting which is then
displayed at 68.
[0023] FIG. 3 illustrates representative electronic circuitry for
the implant. A crystal oscillator composed of crystal X1, inverters
U1a-c, capacitors C1, C2 and feedback resistor R9, provides a
reference frequency to programmable divider U2. The reference
frequency is divided by n and the output used to gate the VCSEL,
D3, via transistor Q7. Transistor Q8 and resistor R8 act to
regulate the maximum current through D3.
[0024] Light from the VCSEL is detected by an array of
photodetectors Q1-Q6. During VCSEL illumination, the disc 34 (FIG.
2) allows selective illumination of phototransistors Q2-Q6, thus
providing a binary representation of the frequency divisor. The
light path from the VCSEL to Q1 is never obstructed, despite the
position of disc 34 so that Q1 conducts each time the VCSEL
illuminates. The output of Q1 is fed to inverter Uld which, in
turn, asserts a positive-going `load` signal to U2 as the VCSEL
illuminates. Upon assertion of the `load` signal, the frequency
divider divisor data is latched on U2 inputs D0-D4. A small
capacitance, on the order of several picofarads, may be placed on
the base of transistor Q1 to allow Q2-Q6 to stabilize prior to
asserting the `load` signal. A period of 2.sup.N clock pulses may
be necessary for the output frequency to stabilize.
[0025] FIG. 4 depicts a block diagram of the external circuitry
which: 1) provides power to the implant; 2) detects the NIR
emission from the implant; and, 3) converts the frequency data from
the implant to a graphical representation of valve position.
[0026] Sensor head 70 is placed over the implant to deliver power
and detect the optical output of the implant. A power oscillator 72
delivers a sinusoidal oscillating current with a nominal frequency
of 200 kHz to a power amplifier 74 which buffers the current to an
isolation transformer 76. The isolation transformer 76 provides
adequate galvanic isolation for a patient-connected connected
device. The output from the isolation transformer is fed to the
sensor head coil 78 which acts as the primary winding of a
transformer to electromagnetically couple energy to the implant's
secondary coil L1 (FIG. 3).
[0027] An optical bandpass filter 64 with center frequency equal to
the emission frequency of the VCSEL, excludes ambient light from
the photodetector 82. Light from the implant VCSEL is transmitted
through bandpass filter 64 and converted to an electrical current
by photodetector 82. This current is roughly a square wave with the
same fundamental frequency as the VCSEL pulses. This signal is
amplified by pre-amp 84 and automatic gain amplifier 86, then
converted to a digital signal by Schmitt trigger 88. A serial data
stream 90, consisting of squarewave pulses, is fed to
microprocessor 92 which measures the frequency of the
aforementioned pulses. The frequency data is then used to index a
look-up table 60 (FIG. 2) through software programming; the result
of which is a numerical indication of the valve pressure setting.
The result is displayed for the user upon a digital or other
graphical display 68.
[0028] A bi-colored Light Emitting Diode, or LED, is also included
in the sensor head 70 to aid positioning of the sensor head over
the implant. In the default state, the red LED 96 is illuminated to
indicate that the sensor head is not over the implant. When the
sensor head is properly aligned over the implant, the implant
begins to receive power through the inductive coupling between coil
78 of the sensor head and L1 of the implant. Once power is applied
to the implant, the VCSEL begins to illuminate in synchrony with
the programmable divider (U2) output. When the External device
begins to detect the VCSEL, e.g. oscillations present on the
`serial data` output of Schmitt Trigger 88, the microprocessor 92
turns off the red LED 96 and illuminates the green LED 94.
[0029] While the present invention has been described in terms of
specific embodiments thereof, it will be understood in view of the
present disclosure, that numerous variations upon the invention are
now enabled to those skilled in the art, which variations yet
reside within the scope of the present teaching. Accordingly, the
invention is to be broadly construed, and limited only by the scope
and spirit of the claims now appended hereto.
* * * * *