Heart Monitor

• US 20100022897A1
• Filed: 05/22/2007
• Published: 01/28/2010
• Est. Priority Date: 05/24/2006
• Status: Active Grant

• Current Assignee: Melys AFS Limited
• Original Assignee: Melys AFS Limited
• Inventors: Parker, Dawood, Bowes, Mark
• Granted Patent: US 9,066,663 B2
• Time in Patent Office: Days
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor

Abstract

A heart monitor for use as a non-invasive screening tool for identifying potential atrial fibrillation in patients comprises a sensor for producing an output waveform of the patient'"'"'s actual sinus rhythm, a processing unit arranged to store the normalised waveform of an ideal sinus rhythm and to compare the actual and ideal sinus rhythm waveforms and to produce an output dependant on the difference on a display. The value of the output is indicative of whether the patient is atrial fibrillation or other cardiac arrhythmia.

Claims

1. A monitor for monitoring the heart of a patient, the monitor comprising a sensor for producing an output waveform of the patient'"'"'s actual sinus rhythm, means for storing the waveform of an ideal sinus rhythm and means for comparing the actual and ideal sinus rhythm waveforms and for producing an output dependant on the difference.

2. A monitor as claimed in claim 1, in which the sensor is arranged to produce an output waveform of the patient'"'"'s actual heart rhythm by sensing the electrical activity of the heart to produce an electrocardiogram.

3. A monitor as claimed in claim 1, in which the sensor is arranged to produce an output waveform of the patient'"'"'s actual heart rhythm by sensing the pulsatile flow of blood through a part of the patient'"'"'s body to produce a plethysmogram.

4. A monitor as claimed in claim 3, in which the sensor comprises a light emitter and a light detector arranged to detect a change in the transmissivity of said part of the patient'"'"'s body as blood flows therethrough in a pulsatile manner.

5. A monitor as claimed in claim 4, in which the light emitter is arranged to emit light having a wavelength of 500 to 1100 nm.

6. A monitor as claimed in claim 1, in which said comparing means is arranged to compare the frequency spectrums of said actual and ideal sinus rhythm waveforms.

7. A monitor as claimed in claim 1, in which said storing means is arranged to store a peak mathematical function representative of the frequency spectrum of said ideal sinus rhythm waveform.

8. A monitor as claimed in claim 7, in which the mathematical function is a Fourier transformation.

9. A monitor as claimed in claim 7, in which the storing means is arranged to store a model of the frequency spectrum of an ideal sinus rhythm waveform.

10. A monitor as claimed in claim 7, in which the peak mathematical function representative of the frequency spectrum of said ideal sinus rhythm waveform is area normalised, such that the area beneath between the frequency limits of interest is 1.

11. A monitor as claimed in claim 7, in which the detector is arranged to produce a patient mathematical function representative of the frequency spectrum of said actual sinus rhythm waveform.

12. A monitor as claimed in claim 11, in which the patient mathematical function is a Fourier transformation.

13. A monitor as claimed in claim 11, in which the patient mathematical function of the actual waveform is area normalised, such that the area beneath between the frequency limits of interest is 1.

14. A monitor as claimed in claim 7, in which stored peak function of the ideal sinus rhythm waveform is stored without an indication of fundamental frequency.

15. A monitor as claimed in claim 14, in which said comparing means is arranged to determine the fundamental frequency of the actual sinus rhythm waveform and to compare the frequency spectrum of said actual sinus rhythm waveform with the frequency spectrum of an ideal sinus rhythm waveform having the same or similar fundamental frequency.

16. A monitor as claimed in claim 15, in which the comparing means is arranged to produce a peak result by summing the products of the produced mathematical function of the actual sinus rhythm with the stored mathematical function of the ideal sinus rhythm using a range of fundamental frequencies for the stored model.

17. A monitor as claimed in claim 16, in which the comparing means is arranged to determine the frequency at which the peak result is maximised.

18. A monitor as claimed in claim 16, in which range of fundamental frequencies extends between 0.6 and 3.3 hertz.

19. A monitor as claimed in claim 16, in which the products are summed using integrals over a range of the frequency spectrum which includes said fundamental frequency and at least one harmonic frequency.

20. A monitor as claimed in claim 16, in which the comparing means introduces a trough function comprising a mathematical function representative of the inverse frequency spectrum of said ideal sinus rhythm waveform.

21. A monitor as claimed in claim 20, in which said trough function is area normalised, the comparing means being arranged to produce a trough result by summing the products of the produced mathematical function of the actual sinus rhythm with the trough function at the determined fundamental frequency.

22. A monitor as claimed in claim 21, in which the trough result is divided by the peak result to provide an index of cardiac arrhythmia.

23. A method of examining the output waveform of a sensor arranged to monitor the heart of a patient, the method comprising comparing the output of the sensor with a stored waveform of an ideal sinus rhythm and producing an output dependant on the difference.