Surgery – Miscellaneous – Devices placed entirely within body and means used therewith
Reexamination Certificate
2002-12-20
2004-06-22
Winakur, Eric F. (Department: 3736)
Surgery
Miscellaneous
Devices placed entirely within body and means used therewith
C607S032000
Reexamination Certificate
active
06752155
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to communication links with implantable medical devices. More particularly, the present invention pertains to techniques for indicating that such communication links are valid.
BACKGROUND OF THE INVENTION
In the field of implantable medical devices, such as cardiac pacemakers, tachyarrhythmia control devices, implantable drug dispensing devices, monitoring devices, and nerve stimulators, it has become common to provide a transceiver system for performing functions such as the remote programming and the telemetering of data out of the implanted device. For example, in such devices, it has become desirable to have the ability to reprogram the device's modes of operation, parameters, and other functions and/or to monitor the performance of such devices, both historically and contemporaneously. Generally, such implantable medical devices are designed to provide two-way telemetry by radio frequency signal transmission between the implanted medical device and a programming head or wand of an external communication device, e.g., external programmer apparatus, to provide for the exchange of coded transmitted information therebetween.
As the complexity of implantable medical devices increases over time, telemetry systems for enabling such implantable devices to communicate with external communication devices, e.g., programmers, has become more important. For example, it is desirable for a user, e.g., a physician, to noninvasively exercise some amount of control over the implantable medical device, e.g., to turn the device on or off after implantation, to adjust various parameters of the implantable medical device after implantation, etc.
Further, as implantable medical devices include more advanced features, it is typically necessary to convey correspondingly more information to the implantable medical device relating to the selection and control of such advanced features. For example, if a pacemaker is selectively operable in various pacing modes, it is desirable that a physician be able to noninvasively select a mode of operation. Further, for example, if a pacemaker is capable of pacing at various rates, or of delivering stimulating pulses of varying energy levels, it is desirable that the physician be able to select, on a patient-by-patient basis, appropriate values for such variable operational parameters.
Not only has the complexity of implantable medical devices led to the need to convey correspondingly more information to the implantable medical device, but it has also become desirable to enable the implanted medical device to communicate information outside of the patient to an external communication device, e.g., programmer. For example, for diagnostic purposes, it is desirable for the implanted device to be able to communicate information regarding its operational status to the physician. Various implantable medical devices are available which can transmit such information to an external communication device, e.g., the transmission of a digitized ECG signal for display, storage, and/or analysis by the external communication device.
As used herein, the term “uplink” and “uplink telemetry” will be used to denote the communications channel for conveying information from the implanted medical device to an external communication device, e.g., a programmer. Conversely, the term “downlink” and “downlink telemetry” will be used to denote the communications channel for conveying information from an external communication device to the implanted medical device.
Various telemetry systems for providing the necessary communication channels between an external communication device and an implanted medical device have been described. For example, typically, telemetry systems are employed in conjunction with an external programmer/processing unit. A programmer for noninvasively programming a cardiac pacemaker is described in the following U.S. patents to Hartlaub, et al., each commonly assigned to the assignee of the present invention: U.S. Pat. No. 4,250,884, entitled “Apparatus for and Method of Programming the Minimum Energy Threshold for Pacing Pulses to be Applied to a Patient's Heart;” U.S. Pat. No. 4,273,132, entitled “Digital Cardiac Pacemaker with Threshold Margin Check;” U.S. Pat. No. 4,273,133, entitled “Programmable Digital Cardiac Pacemaker with Means to Override Effects of Reed Switch Closure;” U.S. Pat. No. 4,233,985, entitled “Multi-Mode Programmable Digital Cardiac Pacemaker;” U.S. Pat. No. 4,253,466, entitled “Temporary and Permanent Programmable Digital Cardiac Pacemaker;” and U.S. Pat. No. 4,401,120, entitled “Digital Cardiac Pacemaker with Program Acceptance Indicator.” Aspects of the programmer that are the subject of the foregoing Hartlaub et al. patents are described in U.S. Pat. No. 4,208,008 to Smith, entitled “Pacing Generator Programming Apparatus Including Error Detection Means,” and in U.S. Pat. No. 4,236,524 to Powell et al., entitled “Program Testing Apparatus.”
Most commonly, telemetry systems for implantable medical devices employ a radio frequency (RF) transmitter and receiver in the implantable medical device, and a corresponding RF transmitter and receiver in the external communication device, e.g., programming unit. Within the implantable medical device, the transmitter and receiver use an antenna for receiving downlink telemetry signals and for radiating RF signals for uplink telemetry. For example, the radiating RF signals may be magnetically coupled through inductive (antenna) coils.
To communicate digital data using RF telemetry, a digital encoding scheme such as described in U.S. Pat. No. 5,127,404 to Wyborny et al., entitled “Improved Telemetry Format,” is used. In particular, for example, in downlink telemetry a pulse interval modulation scheme may be employed wherein the external communication device, e.g., programmer, transmits a series of short RF “bursts” or pulses in which the duration of an interval between successive pulses, e.g., the interval from the trailing edge of one pulse to the trailing edge of the next pulse, encodes the data. For example, a shorter interval may encode a “0” bit while a longer interval may encode a “1” bit.
The external communication devices, e.g., programming devices, typically interface with the implanted medical device through the use of a programming head or paddle. For example, generally, the programming head or paddle is a hand-held unit adapted to be placed on or near the patient's body over the implant site of the patient's implanted medical device. The programming head may effect closure of a reed switch in the implantable medical device using a magnet to initiate a telemetry session. Thereafter, uplink and downlink communication may take place between the implanted medical device's transmitter/receiver and the receiver/transmitter of the external communication device. Other methods of initiating a telemetry session may also be used. For example, a wake-up pulse from an external communication device may be used to wake-up the implanted medical device which polls its downlink receiver at an appropriate interval.
For programming arrangements, and/or for monitoring arrangements, both uplink and downlink telemetry signal strength vary as a function of programming head positioning relative to the implantable device. In other words, the signal strength varies as a function of the coefficient of coupling between the communication head, e.g., programming head including an antenna configuration, and the implanted device. Therefore, it is important for the programming head to be properly positioned over the patient's implant site so that downlink RF signals can be detected in the implantable medical device and uplink signals can be detected by the programming head of the external communication device. For example, if the programming head is too far away from the implantable medical device, the attenuation of RF signals transmitted across the boundary of the patient's skin may be too great, preventing a telemetry link from being
Girma Wolde-Michael
McDowall Paul H.
Medtronic Inc.
Veniaminov Nikita
Winakur Eric F.
LandOfFree
Tactile feedback for indicating validity of communication... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tactile feedback for indicating validity of communication..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tactile feedback for indicating validity of communication... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3294247