Surgery – Diagnostic testing – Measuring fluid pressure in body
Reexamination Certificate
2002-02-15
2004-03-30
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Measuring fluid pressure in body
C600S485000, C600S486000, C073S001570
Reexamination Certificate
active
06712772
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to implantable medical devices, and specifically to implantable pressure sensors.
BACKGROUND OF THE INVENTION
A significant effort has been underway for many years to develop implantable medical devices for direct measurement of physiological parameters of a patient for both temporary and chronic use. Some prior art devices cannot be implanted in the body due to their undesirably large size, limited life span, or high power consumption Challenges exist, for example, in developing efficient commercial pressure transducers, capable of being used in the body of a patient for direct measurement of physiologic pressures such as urinary bladder, abdominal, respiratory, cardiac, venous, arterial, amniotic, and cerebrospinal fluid pressures. For example, suitable implantable cardiac pressure sensors which have very low power consumption for tracking the condition of a heart failure patient are not available.
U.S. Pat. No. 6,248,083 to Smith et al., U.S. Pat. No. 5,969,591 to Fung, U.S. Pat. No. 5,566,680 to Urion et al., U.S. Pat. No. 5,522,266 to Nicholson et al., U.S. Pat. No. 5,184,619 to Austin, U.S. Pat. No. 4,873,986 to Wallace, and U.S. Pat. No. 4,825,876 to Beard, which are incorporated herein by reference, describe the use of piezoresistive elements to facilitate pressure measurements for medical applications.
U.S. Pat. No. 4,407,296 to Anderson, which is incorporated herein by reference, describes a hermetically-sealed piezoresistive pressure transducer for implantation in the body.
U.S. Pat. No. 4,846,191 to Brockeway et al., which is incorporated herein by reference, describes an implantable device for chronic measurement of internal body pressures. The device may include a piezoresistive element.
U.S. Pat. No. 4,023,562 to Hynecek et al., which is incorporated herein by reference, describes an implantable piezoresistive pressure transducer for monitoring internal fluid or pneumatic pressures within the body.
U.S. Pat. No. 4,432,372 to Monroe, which is assigned to Medtronic, Inc. and is incorporated herein by reference, describes apparatus for multiplexing the power and signal leads of an implantable piezoelectric pressure transducer. A device built according to the description in the Monroe patent charges a capacitor located at the pressure transducer site, and, subsequently, allows the capacitor to discharge through a Wheatstone bridge. The capacitor is a fundamental component of this device, as it permits the time-sharing of power functions and sensing functions into only two wires. Although not stated in the Monroe patent, it is known that repeated charging and discharging of capacitors is often associated with significant heat dissipation, and, therefore, increased energy consumption.
U.S. Pat. No. 6,221,024 to Miesel, which is also assigned to Medtronic, Inc. and is incorporated herein by reference, describes a method for sealing oil-filled pressure transducer modules for a chronically-implantable pressure sensor lead. The '024 patent states: “U.S. Pat. No. 4,023,562 describes a pressure transducer comprising a piezoresistive bridge of four, orthogonally disposed, semiconductor strain gauges formed interiorly on a single crystal silicon diaphragm area of a silicon base. A protective silicon cover is bonded to the base around the periphery of the diaphragm area to form a sealed, evacuated chamber. Deflection of the diaphragm due to ambient pressure changes is detected by the changes in resistance of the strain gauges. Because the change in resistance is so small, a high current is required to detect the voltage change due to the resistance change. The high current requirements render the piezoresistive bridge unsuitable for long term use with an implanted power source. High gain amplifiers that are subject to drift over time are also required to amplify the resistance-related voltage change.”
U.S. Pat. No. 5,564,434 to Halperin et al., which is incorporated herein by reference, describes an endocardial lead for implantation in a heart chamber. The lead is able to sense pressure changes via capacitors, and transmit information responsive to the pressure changes to an internal or external medical device.
U.S. Pat. No. 5,330,505 to Cohen, which is incorporated herein by reference, describes implantable sensors for sensing a variety of cardiac physiologic signals.
U.S. Pat. No. 6,238,423 to Bardy, which is incorporated herein by reference; describes apparatus for treating chronic constipation, which includes an implantable pressure sensor for sensing tension in a wall of the digestive system.
U.S. Pat. No. 6,240,316 to Richmond et al., which is incorporated herein by reference, describes the use of implanted pressure sensors in apparatus for treating sleep apnea.
Measurement of pressure in the vicinity of the bladder and lower abdominal region is an important element in devices and methods for treating and controlling urinary incontinence. U.S. Pat. No. 6,135,945 to Sultan, which is incorporated herein by reference, describes apparatus for preventing urinary incontinence. The described apparatus includes an implanted pressure sensor for sensing intra-abdominal pressure. U.S. Pat. No. 4,571,749 to Fischell, which is incorporated herein by reference, describes an artificial sphincter device whose pressure can vary in response to changes in abdominal or intravesical (bladder) pressure. U.S. Pat. No. 5,562,717 to Tippey et al., which is incorporated herein by reference, describes electrical stimulation treatment for incontinence and other neuromuscular disorders, and includes a pressure sensor for determining changes in pressure in the vaginal or anal muscles.
PCT Patent Publication WO 00/19939 to Gross et al., entitled “Control of urge incontinence,” which is assigned to the assignee of the present patent application and incorporated herein by reference, describes a device for treatment of urinary urge incontinence comprising a system in which imminent involuntary urine flow is sensed, and appropriate nerves or muscles are stimulated to inhibit the flow.
U.S. Patent Publication WO 00/19940 to Gross et al., entitled, “Incontinence treatment device,” which is assigned to the assignee of the present patent application and incorporated herein by reference, describes a device for treating urinary stress incontinence comprising a system in which imminent involuntary urine flow is sensed, and nerves or muscles are stimulated to inhibit the flow.
In general, for implanted pressure sensors, issues of size, durability, accuracy and, particularly, power consumption are major considerations that must be addressed in order to ensure that the goals of the application are achieved.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide improved apparatus and methods for reducing power consumption in a pressure sensor implanted in the body of a patient.
It is also an object of some aspects of the present invention to provide improved methods and apparatus for reducing heat dissipation in a pressure sensor implanted in the body of a patient.
It is a further object of some aspects of the present invention to provide improved apparatus and methods for increasing the useful lifetime of an implantable device.
It is yet a further object of some aspects of the present invention to provide improved methods for enabling the coupling of MP35N wires and other materials in lead wires to circuitry in an implantable device.
It is still a further object of some aspects of the present invention to provide less-complicated methods and apparatus for producing an implantable device.
It is also an object of some aspects of the present invention to provide improved methods and apparatus for producing a low cost implantable device.
In preferred embodiments of the present invention, apparatus to achieve the above objects comprises at least one implantable pressure-sensing device coupled to a control unit. The sensing device is preferably implanted in a patient's body at a location chosen in accordance w
Cohen Ehud
Vaingast Shai
Biocontrol Medical Ltd.
Hindenburg Max F.
Ladas & Parry
Natnithithadha Navin
LandOfFree
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