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Patent

Implantable pressure transducer

TL;DR: In this article, a surgically implantable pressure transducer for measuring pressure of fluid or tissue in a body chamber such as brain ventricle of a patient suffering hydrocephalus or a severe head injury is described.
Abstract: A wireless, surgically implantable pressure transducer for measuring pressure of fluid or tissue in a body chamber such as brain ventricle of a patient suffering hydrocephalus or a severe head injury. The transducer includes a coaxial variable capacitor electrically connected across an inductor to form a parallel resonant L-C circuit. Alternatively, a coaxially variable inductor may be connected across a capacitor to form the L-C circuit. A bellows is mechanically connected to the variable component to vary the value of capacitance or inductance and hence the resonant frequency of the L-C circuit in response to pressure changes of the fluid in which the bellows is immersed. The transducer is electromagnetically coupled to an external source of variable-frequency oscillatory energy such as a grid-dip oscillator which enables external detection of the transducer resonant frequency which is in turn indicative of the level of fluid pressure being sensed.
Citations
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Patent
23 Apr 2007
TL;DR: In this article, a system and method for waking up a satellite implantable medical device ('IMD') from a sleep state in which power consumption by the satellite IMD is essentially zero.
Abstract: A system and method for waking up a satellite implantable medical device ('IMD') from a sleep state in which power consumption by the satellite IMD is essentially zero. The satellite IMD may be adapted to perform one or more designated measurement and/or therapeutic functions. The satellite IMD includes a wake-up sensor that is adapted to sense the presence or absence of a wake-up field generated by a primary IMD or an external device. The wake-up field may be an electromagnetic field, a magnetic field, or a physiologically sub-threshold excitation current (i.e., E-field). Upon sensing by the wake-up sensor of the wake-up field, other components of the satellite IMD, which may include a controller, a sensing and/or therapy module, and/or a communications module, are awakened to perform one or more designated functions.

496 citations

Patent
21 Sep 2012
TL;DR: In this paper, a system for enabling a medical device is described, which includes a cradle having a magnet for generating a magnetic field, and a switch, indicator, logic circuitry, delay circuit and detect circuit for coupling a power source to electronic circuitry.
Abstract: A system for enabling a medical device. The system includes a cradle having a magnet for generating a magnetic field. The cradle supports and aligns the medical device in a predetermined orientation. Medical device placed in the cradle exposes a magnetic sensitive switch to the magnetic field of the magnet that produces a change in state of the magnetic sensitive switch. Medical device further includes a switch, indicator, logic circuitry, delay circuit, and detect circuit for coupling a power source to electronic circuitry. In a first mode of operation the medical device can be turned on and then turned off. In a second mode of operation the medical device cannot be turned off after being turned on.

362 citations

Patent
22 Jan 2002
TL;DR: In this paper, the progress of a endovascular cardiac repair can be monitored by inserting a pressure transducer sensor using a catheter into a chamber of the heart during the procedure and then using a small, hand-held read out device to measure pressure easily, safely, inexpensively and accurately.
Abstract: The progress of a endovascular cardiac repair can be monitored by inserting a pressure transducer sensor using a catheter into a chamber of the heart during endovascular repair and then using a small, hand-held read out device to measure pressure easily, safely, inexpensively and accurately. In one aspect a sensor is introduced into the body by the steps of folding or rolling the sensor into a cylinder, loading it into a catheter, and deploying into the heart chamber by allowing it to unroll or unfold, either by itself or facilitated by the incorporation of a super-elastic alloy component.

342 citations

Patent
16 Nov 2002
TL;DR: In this article, the authors describe a system for communicating with an implant within a patient's body using acoustic telemetry, which includes an external communications device attachable to the patient's skin.
Abstract: Systems and methods for communicating with an implant within a patient's body using acoustic telemetry includes an external communications device attachable to the patient's skin. The device includes an acoustic transducer for transmitting acoustic signals into the patient's body and/or for receiving acoustic signals from the implant. The device includes a battery for providing electrical energy to operate the device, a processor for extracting data from acoustic signals received from the implant, and memory for storing the data. The device may include an interface for communicating with a recorder or computer, e.g., to transfer data from the implant and/or to receive instructions for controlling the implant. The device is secured to the patient's skin for controlling, monitoring, or otherwise communicating with the implant, while allowing the patient to remain mobile.

334 citations

Patent
19 Nov 1999
TL;DR: An intrabody implantable system for long-term, real-time monitoring of at least one parameter associated with heart performance is described in this paper, where the system includes a first sensor being implantable within a heart and being for collecting information pertaining to a pressure in a first cavity of the heart; at least another sensor being implantedable in an blood vessel supporting blood flow into or out of a second cavity of a heart, the at least additional sensor being for collect information regarding a pressure and a flow within the blood vessel; and the device implantable in the body and
Abstract: An intrabody implantable system for long-term, real time monitoring of at least one parameter associated with heart performance. The system includes (a) a first sensor being implantable within a heart and being for collecting information pertaining to a pressure in a first cavity of the heart; (b) at least one additional sensor being implantable in an blood vessel supporting blood flow into or out of a second cavity of the heart, the at least one additional sensor being for collecting information pertaining to a pressure and a flow within the blood vessel; and (c) at least one device implantable in the body and being in data communication with the first sensor and the at least one additional sensor, the at least one device being for receiving the information pertaining to the pressure in the first cavity of the heart and the information pertaining to the pressure and the flow within the blood vessel and for relaying the information pertaining to the pressure in the first cavity of the heart and the information pertaining to the pressure and the flow within the blood vessel outside the body.

321 citations

References
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Patent
Gerald R. Severson1
29 Nov 1974
TL;DR: A fluid pressure sensor for use internal to the human body including a completely ceramic sectioned outer shell having an opening therein for allowing fluid access to a thin metal diaphragm member is presented in this article.
Abstract: A fluid pressure sensor for use internal to the human body including a completely ceramic sectioned outer shell having an opening therein for allowing fluid access to a thin metal diaphragm member. The thin metal diaphragm member is disposed between the sectioned outer shell by diffusion bonding in order to limit exposure of the human tissue solely to the diaphragm member and the ceramic shell. A variable tuned LC circuit is responsive to fluid pressure for establishing a predetermined electrical parameter. The electrical parameter is capable of affecting an electromagnetically responsive electrical circuit means located external to the human body for providing data indicative of the fluid pressure. The thin diaphragm member constitutes one plate of the LC circuit and the remainder of the LC circuit is located beneath the thin diaphragm member so as to be protected from fluid and moisture.

94 citations

Patent
H Workman1
22 Jan 1971
TL;DR: In this article, a high repetition rate of the feedback signal limits displacement of the diaphragm within very small tolerances to reduce the compliance error of a compliant diaphram.
Abstract: An air-filled catheter transmits an intravenous blood pressure to a pressure-sensing transducer having a coil connected to a flexible membrane or diaphragm which defines one side of the catheter chamber. A digital feedback signal is generated in response to displacement of the membrane; and this feedback signal is used to energize the coil and drive the membrane back to its original position. A highly sensitive (i.e. compliant) diaphragm is used; and the high repetition rate of the feedback signal limits displacement of the diaphragm within very small tolerances to reduce the compliance error of the diaphram. The average value of the current in the driving coil necessary to displace the diaphragm to offset the catheter pressure is a measure of the intravenous pressure.

66 citations

Patent
06 May 1958

44 citations

Patent
20 Dec 1968
TL;DR: An expansible bellows having a variable internal volume is mounted in a housing adapted for implantation in the skull of a patient suffering from hydrocephalus as mentioned in this paper, where a tube extends from the bellows for insertion into a ventricle of the brain.
Abstract: An expansible bellows having a variable internal volume is mounted in a housing adapted for implantation in the skull of a patient suffering from hydrocephalus. A tube extends from the bellows for insertion into a ventricle of the brain. When so installed, the bellows is filled with ventricular fluid at an average or static pressure. Pulsation of choroid-plexus blood vessels in the brain tends to cause a periodic increase in fluid pressure, but bellows expansion in response to increased pressure minimizes the actual increase in fluid pressure. The resulting suppression of pulsatile pressure peaks and dissipation of energy by the bellows appears to be an effective technique for treating hydrocephalus.

44 citations