Surgery – Miscellaneous – Devices placed entirely within body and means used therewith
Reexamination Certificate
2000-02-24
2001-10-30
Lacyk, John P. (Department: 3736)
Surgery
Miscellaneous
Devices placed entirely within body and means used therewith
C600S437000
Reexamination Certificate
active
06308715
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to non-invasive diagnoses of medical implant devices, and more particularly to ultrasonic detection of restenosis in a stent.
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 amount of blood flowing through a stent 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.
While such conventional techniques may be effective in avoiding the need to perform invasive surgery, there are however several drawbacks associated therewith. For example, the transceiver included in the implant device typically includes complex electrical circuitry such as mixers, amplifiers, microprocessors, etc. for receiving an interrogation signal and for transmitting a response signal based on the output of the sensors. Such complex circuitry has a relatively high cost associated therewith. In addition, the complexity of the circuitry increases the likelihood that the device itself may be defective. This would then require further invasive surgery and could even result in physical harm to the patient.
Still another shortcoming with conventional implant devices with sensors included therein is power concerns. Some type of circuit for providing power to the transceiver is necessary. The circuit may be a built-in power source such as a battery, or a circuit which derives operating power from an external excitation signal using magnetic or electromagnetic coupling. In either case, again the complexity of the circuit and/or the need to replace the battery periodically adds to the cost of the device and increases the opportunity for failure or defects.
In view of the aforementioned shortcomings associated with conventional implant devices, there is a strong need in the art for a medical implant system and method, particularly with respect to a stent, which can remotely interrogate the stent but which does not require complex electrical circuitry such as mixers, amplifiers, microprocessors, etc. There is a strong need for a stent which carries out its function within a human or other living animal, and can be remotely interrogated simply and reliably. Moreover, there is a strong need for a stent which does not rely on complex energy conversion circuits in order to operate.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a diagnostic system is provided. The system includes a stent implantable within a blood vessel of a living animal and operatively configured to prevent the vessel from collapsing. The stent may be a typical commercially available stent or one specially designed to exhibit a mechanical transfer function which, in response to mechanical excitation, causes the structure to produce an acoustic signal having a characteristic which is modulated in relation to the presence of restenosis within the stent. The system further includes an exciter for acoustically transferring mechanical energy to the stent from outside the living animal, and a receiver located outside the living animal which detects the acoustic signal produced by the structure, processes the acoustic signal in relation to the mechanical transfer function, and provides an output indicative of the parameter based on the processed acoustic signal.
The system may be based on existing ultrasonic imaging equipment, or can comprise a system designed specifically for analyzing a stent. A combination of software and/or hardware is provided for analyzing ultrasonic data reflected or reradiated from the stent in response to ultrasonic pulses. The data is digitized and processed using one or more algorithms such as a Fast Fourier Transform (FFT), wavelets, etc. By analyzing response parameters such as amplitude, harmonic content, phase and/or modulus data as a function of frequency, for example, it has been found that the degree of restenosis within the stent may be diagnosed. A signature database for storing response data for one or more standard stents of different sizes, types, manufacturers, etc., is provided. The system uses a pattern recognition or matching algorithm to identify the particular stent within the body, and uses such information to normalize the acquired data, set baselines, etc.
A feature of the invention is that it can be implemented with limited hardware and/or software in combination with conventional ultrasonic imaging equipment. Alternatively, the present invention may be carried out as an entirely new system configured specifically for the detection of restenosis in stents.
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.
Dunlap Thoburn T.
Kolkowski Brian M.
Lacyk John P.
Marmor II Charles
PMD Holdings Corp.
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