System and method for triggering a device based on an electrocardiogram signal

• US 20070142734A1
• Filed: 12/15/2005
• Published: 06/21/2007
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Ivy Biomedical Systems Inc
• Original Assignee: Ivy Biomedical Systems Inc
• Inventors: Mentelos, Richard, Harris, Mark
• Granted Patent: US 7,920,912 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/301 providing electrical separation, e.g. by using isolating transformers or optocouplers
• CPC Class Codes: A61B 5/308 for electrocardiography [ECG]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 8/543 involving acquisition triggered by a physiological signal

Abstract

A system and method for triggering an external device in response to an electrocardiogram signal. In one embodiment the method includes determining a peak in the electrocardiogram signal, determining if the electrocardiogram signal is rising or falling at the peak in the signal and triggering a device in response to the rising or falling peak. In one embodiment of the invention an external trigger signal is produced only a rising peak is detected. In one embodiment, the system includes a microprocessor, a peak detector and a trigger circuit. The trigger circuit outputs a trigger signal to an external device when signaled by the peak detector and not inhibited by a signal from the microprocessor.

Claims

1. A system for selectively triggering a device in response to an electrocardiogram signal comprising:

a microprocessor comprising a microprocessor digital input and a microprocessor control output;

a peak detector comprising a peak detector input and a peak detector output; and

a trigger circuit having a peak detection control input, a microprocessor control input and trigger output, the peak detection control input in communication with the peak detector output and the microprocessor control input in communication with the microprocessor control output,

wherein said trigger circuit generates an output signal on the trigger output in response to a peak detection control input signal from the peak detector output and a microprocessor control input signal from the microprocessor control output, and

wherein the microprocessor control signal is asserted if the electrocardiogram signal has a predetermined number of decreasing values and not asserted if the electrocardiogram signal has a predetermined number of increasing values.

2. The system of claim 1 wherein the trigger circuit generates the trigger output when the peak detector input is asserted and the microprocessor control input is not asserted.

3. The system of claim 1 wherein the microprocessor control signal is asserted if the electrocardiogram signal is inverted and has a predetermined number of increasing values and not asserted if the electrocardiogram signal is inverted and has a predetermined number of decreasing values

4. The system of claim 1 further comprising an A/D converter comprising an A/D converter input and an A/D converter output, wherein the digital converter output is in communication with the microprocessor digital input.

5. The system of claim 1 further comprising a pre-peak filter comprising a filter input and a filter output wherein the filter output is in communication with the peak detector input.

6. A system as defined in claim 5 wherein the pre-peak filter comprises a differentiator in communication with a full wave rectifier, the differentiator comprising a differentiator input and the full wave rectifier comprising a full wave output, the differentiator input being the pre-peak filter input and the full wave rectifier output being the pre-peak filter output.

7. A system as defined in claim 1 wherein the peak detector selects peaks between 7 and 70 milliseconds in length.

8. A system as defined in claim 1 wherein the peak detector further comprises a peak threshold input.

9. A system as defined in claim 8 further comprising a threshold filter having a threshold input and a threshold output, the threshold output in communication with the peak threshold input and the threshold input in communication with the pre-peak filter output.

10. A system as defined in claim 9 wherein the threshold filter generates a threshold output signal when the threshold input signal comprises two peaks, the first being no less than sixty percent of the second.

11. A system for imaging a patient comprising

a microprocessor comprising a microprocessor digital input and a microprocessor control output;

a peak detector comprising a peak detector input and a peak detector output; and

a trigger circuit having a peak detection control input, a microprocessor control input and trigger output, the peak detection control input in communication with the peak detector output and the microprocessor control input in communication with the microprocessor control output, and

an imaging device, comprising an imaging input, wherein the imaging input is in communication with the trigger output.

wherein said trigger circuit generates an output signal on the trigger output in response to a peak detection control input signal from the peak detector output and a microprocessor control input signal from the microprocessor control output, and

wherein the microprocessor control signal is asserted if the electrocardiogram signal has a predetermined number of decreasing values and not asserted if the electrocardiogram signal has a predetermined number of increasing values.

12. The system of claim 11 wherein the microprocessor control signal is asserted if the electrocardiogram signal is inverted and has a predetermined number of increasing values and not asserted if the electrocardiogram signal is inverted and has a predetermined number of decreasing values

13. The system of claim 11 wherein the imaging device is a gamma camera.

14. A method for selectively triggering a device in response to an electrocardiogram signal comprising the steps of:

determining a peak in the electrocardiogram signal;

determining if the electrocardiogram signal is rising or falling at an inflection point of the electrocardiogram signal; and

triggering a device in response to the determination.

15. The method of claim 14 further comprising manipulating the electrocardiogram signal comprising;

rectifying the electrocardiogram signal;

filtering the rectified electrocardiogram signal; and

selecting only filtered signals with two peaks, the first being no less than sixty percent of the second,

prior to determining the peak in the electrocardiogram.

16. The method of claim 14 further comprising detecting electrocardiogram peaks with a period between seven and seventy milliseconds.