Efficient generation of sensing signals in an implantable medical device such as a pacemaker or ICD

• US 6,275,734 B1
• Filed: 12/30/1998
• Issued: 08/14/2001
• Est. Priority Date: 12/30/1998
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: McClure, Kelly H., Mouchawar, Gabriel
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US09/223,422
• Time in Patent Office: 958 Days
• Field of Search: 607/27
• US Class Current: 607/27
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

An implantable cardiac device such as a pacemaker or an implantable cardioverter defibrillator (ICD) that stores a broad band electrogram signal in response to the detecting of a particular cardiac event. The system includes an external programmer which is capable of accessing the stored electrogram via a telemetry circuit so that the stored electrogram can be downloaded and reviewed on a display of the external programmer. The external programmer is also equipped with a digital filter emulator that is capable of emulating the filtering of the broad band electrogram signal that is being provided to the processor of the implanted cardiac device. The emulator therefore allows a treating physician to review an emulation of the waveform that the processor of the implanted cardiac device is seeing when the processor is initiating the delivery of therapeutic electrical stimulation to the heart.

Claims

1. A system for displaying cardiac signals, comprising:

an implantable cardiac stimulation device having;

means for receiving a cardiac signal;

filtering means for filtering the cardiac signal with a first filter to produce a first signal and for filtering the cardiac signal with a second filter to produce a second signal, wherein the second filter is selected to highlight a characteristic feature of heart activity;

control means for controlling the delivery of therapeutic electrical stimulation to the heart based, at least in part, on the second signal; and

transmitting means for transmitting the first signal; and

an external programmer having;

receiving means, telemetrically coupled to the transmitting means, for receiving the first signal;

processing means for processing the first signal and generating an emulated version of the second signal; and

displaying means for displaying at least one of the received first signal or the emulated version of the second signal.

2. The system of claim 1, wherein the first filter has a first bandwidth and the second filter has a second bandwidth that is less than the first bandwidth.

3. The system of claim 2, wherein:

the first filter is a broad band filter and the first signal is a broad band filtered intracardiac electrogram (IEGM) signal; and

the second filter is a narrow band filter and the second signal is a narrow band filtered intracardiac electrogram (IEGM) signal for detecting one of atrial and ventricular cardiac signals.

4. The system of claim 3, wherein the first filter has a bandwidth of between 0.1 and 400 Hz and wherein the second filter has a bandwidth of between 10 and 100 Hz.

5. The system of claim 1, wherein the external programmer can be communicatively linked to the transmitting means so as to be able to receive the first signal from the filtering means in real-time.

6. The system of claim 1, wherein the implantable cardiac stimulation device further comprises:

a memory for storing the first signal;

detection means for detecting when a predetermined criteria has been met; and

wherein the control means includes means for triggering the memory to store a selected portion of the first signal when the predetermined criteria has been met.

7. The system of claim 1, wherein the displaying means is adapted to display the first signal and the emulated version of the second signal substantially simultaneously.

8. The system of claim 1, wherein the displaying means is adapted to programmably select the display of at least one of the first signal and the emulated version of the second signal.

9. The system of claim 1, wherein the emulating means comprises a digital filter that digitally filters the first signal to produce the emulated version of the second signal.

10. The system of claim 9, wherein the digital filter has an output which is a function of the current input and at least one of the previous inputs or previous outputs to the digital filter.

11. The system of claim 9, wherein the digital filter is comprised of an infinite impulse response (IIR) digital filter.

12. The system of claim 11, wherein the infinite impulse response digital filter provides an output signal as defined by the formula: