Surgery – Miscellaneous – Devices placed entirely within body and means used therewith
Reexamination Certificate
2000-06-14
2001-12-18
Nasser, Robert L. (Department: 3736)
Surgery
Miscellaneous
Devices placed entirely within body and means used therewith
C128S903000, C600S504000, C600S586000
Reexamination Certificate
active
06330885
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to medical implant devices, and more particularly to devices which may be interrogated remotely from outside the body.
BACKGROUND OF THE INVENTION
Various types of medical implant devices have been developed over the years. In many instances, such devices enable humans to live longer, more comfortable lives. Implant devices such as pacemakers, artificial joints, valves, grafts, stents, etc. provide a patient with the opportunity to lead a normal life even in the face of major heart, reconstructive, or other type surgery, for example.
It has been found, however, that the introduction of such implant devices can sometimes lead to complications. For example, the human body may reject the implant device which can ultimately lead to infection or other types of complications. Alternatively, the implant device may malfunction or become inoperative Therefore, it is desirable to be able to monitor the condition of the implant device. On the other hand, it is highly undesirable to have to perform invasive surgery in order to evaluate the condition of the device.
Still further, it is desirable to be able to monitor conditions related to the use of implant devices. For example, in heart patients it may be helpful to know the extent of occlusion in a stent or graft in order to evaluate the health of the patient. Again, however, it is undesirable to have to perform invasive surgery in order to evaluate such conditions.
Techniques have been developed which enable the function of an implant device to be monitored remotely from outside the body of the patient. These techniques involve including one or more sensors in the device for sensing the condition of the device. The device further includes a small transceiver for processing the output of the sensors and transmitting a signal based on the output. Such signal typically is a radio frequency signal which is received by a receiver from outside the body of the patient. The receiver then processes the signal in order to monitor the function of the device.
Micro-miniature sensors have been proposed for use in implant devices. For example, PCT Application WO 98/29030 to Govari et al. discusses the use of piezoelectric pressure sensors or micro-machined silicon strain gages in a stent. Pressure changes from one sensor to another are considered indicative of constriction of the stent. U.S. Pat. No. 5,807,258 to Cimochowski et al. describes using surface acoustic wave (SAW) sensors in a graft. Transit times or Doppler measurements using the SAW sensors enable one to determine fluid flow or velocity.
In each such case, however, the amount of constriction (i.e., build up of restenosis or other biological matter) can only be inferred and is not directly measured. For example, blood flow or velocity may not be noticeably affected until after the build-up of a significant amount of restenosis. This can lead to false diagnoses and/or require occlusion be in a more advanced state prior to detection. Furthermore, measurements based on transit times or Doppler measurements, for example, can require complex processing which expose such approaches to another source for error.
In view of the aforementioned shortcomings associated with conventional implant devices, there is a strong need in the art for a medical implant device which can detect the buildup of biological matter more directly compared to conventional devices. There is a strong need for a medical implant device which can provide an indication of the amount of occlusion, extent of infection, etc. more directly and which can be remotely interrogated simply and reliably.
SUMMARY OF THE INVENTION
The present invention is responsive to the aforementioned shortcomings with conventional devices, and is directed towards an implant device to be implanted within a living animal. One or more sensors are included in the device and serve to detect directly the amount of biological material such as restenosis which builds up on the sensors. This provides a direct indication of the amount of biological material which may be occluding a vein or artery, for example. The output of the sensor is coupled to a communication element which communicates information to a remote element outside the living animal so that the information may be processed to provide a diagnosis.
In such manner, the present invention does not require the calculation of transit times, Doppler measurements or pressure gradients between different sensors in order to be able to infer the amount of build up of biological material. Rather, the build up of biological matter on a given sensor itself is detected to indicate more directly the occurrence of restenosis, etc.
In one embodiment, the implant device includes a SAW sensor. The output of the sensor is designed to be a function of the amount of biological material which builds up on the surface of the sensor. More specifically, the output of the sensor varies as the accretion of biological material increases. For example, the accretion of biological material alters the extent to which the surface acoustic wave is able to couple energy to the surrounding medium within the body of the living animal.
In another embodiment, the implant device includes a microelectrical-mechanical sensor (MEMs) device, hereinafter referred to as a MEMs sensor. The MEMs sensor in a preferred embodiment includes at least one cantilever beam. The amount of build up of biological matter on the cantilever beam varies the output of the sensor, so as to provide an indication of the amount of accretion.
According to one particular aspect of the invention, an implant device is provided which includes a structure implantable within a living animal; a sensor included as part of the structure, the sensor being operatively configured to detect accretion of biological material on the sensor by producing an output which varies as a function of the accretion of biological material on the sensor; and a communication element included as part of the structure and operatively coupled to the output of the sensor, the communication element being configured to communicate information based on the output of the sensor wirelessly to a remote element located outside the living animal.
In accordance with another aspect of the invention, a diagnostic system is provided which includes a structure implantable within a living animal; a sensor included as part of the structure, the sensor being operatively configured to detect accretion of biological material on the sensor by producing an output which varies as a function of the accretion of biological material on the sensor; a communication element included as part of the structure and operatively coupled to the output of the sensor, the communication element being configured to communicate information based on the output of the sensor wirelessly to a remote element located outside the living animal; the remote element configured to receive the information from the communication element outside the living animal; and a processor for processing the information received by the remote element based on the function to provide a diagnostic output.
To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
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Dickens, Jr. Elmer D.
Spillman Jr. William B.
Weissman Eric M.
Carter Ryan
Dunlap Thoburn T.
Nasser Robert L.
PMD Holdings Corporation
Saralino Mark D.
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