Apparatus for processing body signals

• US 6,577,892 B2
• Filed: 02/19/2001
• Issued: 06/10/2003
• Est. Priority Date: 02/18/2000
• Status: Active Grant

• Current Assignee: Biotronik Mess-Und Therapiegeraete GmbH & Company Ingenieurbuero Berlin (Biotronik SE & Company KG)
• Original Assignee: Biotronik Mess-Und Therapiegeraete GmbH & Company Ingenieurbuero Berlin (Biotronik SE & Company KG)
• Inventors: Schomburg, Richard A.
• Primary Examiner(s): Wolfe, Willis R.
• Application Number:
  US09/788,756
• Publication Number:
  US 20010021814A1
• Time in Patent Office: 841 Days
• Field of Search: 600/300, 600/301, 600/309, 600/310, 600/322, 600/323, 600/324, 600/336, 600/341, 600/473, 600/476, 600/508, 600/509, 600/515, 600/516, 600/517, 600/518, 600/523, 128/923, 702/71, 702/72, 702/75, 702/76, 708/3, 708/306, 708/308, 708/422, 708/423
• US Class Current: 600/509
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

Apparatus for processing body signals, comprising at least one sensor (10, 12) for picking up in particular electrical signals from a living body, and means (16, 18) for preparing picked-up signals for further processing, and at least one first memory (22) for a picked-up measurement signal or signal portions, comprising at least one second memory (26) which contains a predeterminable comparison signal which is finite in respect of time, and signal comparison means (24) which are connected to the second memory (26) and the first memory (22) and which are adapted for sliding comparison of signal portions, which overlap in respect of time, of the measurement signal in the first memory (22) to the comparison signal stored in the second memory (26) and for output of a correlation coefficient representing the similarity of each compared signal portion of the measurement signal to the comparison signal.

Claims

1. An apparatus for processing body signals, comprising;

at least one sensor for picking up electrical signals from a living body,

means for preparing for further processing picked-up signals;

at least one first memory for a picked-up measurement signal or portion thereof,

at least one second memory that contains a predeterminable comparison signal that is finite in respect of time, and

a means for signal comparing that is connected to the second memory and the first memory and that is adapted for sliding comparison of signal portions, which overlap in respect of time, of the measurement signal in the first memory to the comparison signal stored in the second memory and for output of a correlation coefficient representing the similarity of each compared signal portion of the measurement signal to the comparison signal.

2. The apparatus as set forth in claim 1 characterised in that an integral in relation to time or its sum of the time-discrete signal values is zero.

3. The apparatus as set forth in claim 1 characterised in that the signal comparing means is connected to a logarithm memory that contains tables of logarithms for the values of the measurement and comparison signals, wherein the signal comparing means are so designed for forming the correlation coefficients that they execute multiplication of a value of the comparison signal from the second memory by a corresponding value of the measurement signal from the first memory in such a way that firstly the logarithms of the values to be multiplied themselves or the values respectively closest thereto are read out of the logarithm memory and then the two logarithms are added.

4. The apparatus of claim 3 further comprising a detection means that is connected to the signal comparison means and that is designed to detect maximum values and/or zero-passages of a signal formed by the correlation coefficients.

5. The apparatus of claim 4 further comprising a means for comparing threshold values that is connected to the signal comparing means and a threshold value memory containing a threshold value and is designed to output an identification signal as soon as the correlation coefficient outputted by the signal comparing means exceeds the threshold value.

6. The apparatus of claim 5 wherein the threshold value comparing means is additionally so designed that it outputs an identification signal when a correlation coefficient for a first signal portion from the first memory exceeds the threshold value and for a second signal portion which is recorded in respect of time after the first signal portion reaches or is below the value zero.

7. The apparatus of claim 6 further comprising a locating means which is connected to the threshold value comparing means and the detection means and which is so designed that it associates a location signal with that signal portion of the measurement signal in the first memory, in respect of which the signal formed by correlation coefficients has a maximum within that portion of the signal formed by the correlation coefficients, for which the threshold value comparing means output an identification signal.

8. The apparatus as set forth in claim 7 further comprising threshold value-forming means which is connected to the threshold value memory and the locating means and is so designed that it forms a new threshold value after the occurrence of a location signal in such a way that the correlation coefficient associated with the location signal is involved in weighted fashion in the formation of the new threshold value.

9. The apparatus of claim 8 further comprising a means for forming a new comparison signal, which is connected to the second memory and is so designed that a measured signal portion which corresponds to a signal feature to be detected is transformed to the comparison signal in such a way that its integral in relation to time is zero and the comparison signal formed in that way is transferred into the second memory.

10. The apparatus of claim 9 further comprising comparison signal-adaptation means for adaptation of the comparison signal which is connected to the first memory, the second memory and the locating means and is so designed that it forms a new adapted comparison signal when the locating means output a location signal, wherein the adapted comparison signal is formed using that measurement signal portion from the first memory, with which the location signal is associated.

11. The apparatus of claim 10 wherein the comparison signal-adaptation means is so designed that the comparison signal valid prior to adaptation, for forming the comparison signal valid after adaptation, is weighted with a factor 1-α

while that signal portion in the first memory which has triggered the identification signal by means of the signal comparison means and the locating means, is involved with a weighting factor α

in the comparison signal which is valid after adaptation.

12. The apparatus of claim 11 wherein the comparison signal-forming means and/or the comparison signal-adaptation means are so designed that the comparison signal which is so formed or adapted is standardised in such a way that the amplitude thereof corresponds to the maximum amplitude of the measurement signal.

13. The apparatus of claim 12 further comprising a database which contains a plurality of comparison signals and is connected to the second memory in such a way that comparison signals can be transferred from the database into the second memory and vice-versa.

14. The apparatus of claim 13 further comprising means for analysis of the characterising properties of the preferably adapted comparison signal.

15. The apparatus of claim 14 wherein a first said at least one sensor is for cardiac signals associated with the left ventricle or atrium and a second said at least one sensor is for cardiac signals associated with the right ventricle or atrium, means connected to said first and second said at least one sensors for forming a bimodal signal from the two cardiac signals in such a way that the bimodal signal contains a feature of the first signal prior to conduction into the respective other ventricle or atrium and the corresponding feature after conduction thereof, so that the feature is contained in the bimodal signal at a spacing in respect of time corresponding to the conduction time on the one hand in its form prior to conduction and on the other hand in its form after conduction, and characterised in that the second memory contains a bimodal comparison signal which can be adapted to the bimodal signal so that after adaptation of the bimodal comparison signal to the bimodal signal the conduction time can be determined by analysis of the comparison signal.