A Spanish research group from the Department of Signal Theory and Communications at University of Alcalá (Spain) has designed a device and method for detecting ventricular repolarization alternans based on continuous time analysis and the extraction of the information using windowing.
As a main feature, the method presents high robustness against noise and it is very robust against variability of heart rate due to standardization techniques used.
Moreover, it includes a procedure to separate the repolarization information from artifacts. Because of these characteristics, it is particularly suitable for implementation in portable monitoring devices and implantable devices.
The group is looking for companies of Medical equipment and health technology to reach licensing agreements or collaboration and commercial agreements for technical assistance.
New and innovative aspects
The present invention has the following properties:
-The ECG is processed in the time domain.
-It is based on spectral analysis, using the ECG as an original signal sin the analysis.
- A small number of heart beats is used in the analysis, from 8 to 32.
-It is robust against noise, being valid for the analysis of any type of electrical signal of the heart from any existing device, like Holter monitoring long term, signals from exercise testing, cardiac monitoring devices or intracavitary signals from electrophysiological studies or implantable devices.
-It allows recover the waveform of the alternation and define the temporal moments of the ECG in which they appear.
Main advantages of its use
Using a reduced number of beats in the analysis:
-The variability effect of heart rate decreases.
-The resolution of the analysis improves.
-The computational cost is reduced, making it valid for implementation into any existing device, including portable or implantable devices.
Because it is robust against noise:
- The method is valid for the analysis of any type of electrical heart signal from any source or existing device.
The designed scheme consists of the following:
1) Extraction and / or storage of the electrocardiogram (ECG).
Its function is to capture the ECG signal which may comprise one or more leads. This acquisition mechanism is implemented in the device itself. Otherwise, the mechanism will adapt the signals taken by any other qualified device by physically reading of the data or the receipt via any transmission medium.
2) Adaptation of the signal and elimination of noise and artifacts.
Its function is to adapt the input signal to facilitate analysis, and remove noise and artifacts. It can be implemented by any method such as linear filtering, non-linear filtering or multirate processing.
3) Extraction of information of T-wave alternans (TWA) using the synthesis of a periodical window and the windowing of the signal.
Its function is to process block of beats to discriminate spectral information that non corresponds to the TWA. The designed scheme is based on the average of the spectral by means of windowing in different areas of the signal. This scheme no only provides more robustness against noise, but it increases the resolution of the detection, eliminating the effect which can cause the use of windows with small duty cycle. This stage is divided into the following blocks:
-QRS detection: Its mission is to detect the QRS complex of beats blocks.
-Heart rate determination: It computes heart rate and its standard deviation.
-Synthesis of the window: Its function is to synthesize the window used to extract the information from the TWA.
-Delay: Its function is to generate a shifted version of the periodic window.
-Windowing: This block performs the product of the signal with the shifted version of the corresponding periodic window.
4) Post-processing for improving TWA detection
This stage has the mission to increase the significance of the alternans over the noise. It will implement one or more of the following blocks: elimination of ECG background, trend estimation and noise elimination.
5) Detection of TWA from RAOT calculation and decision.
6) Presentation of the results.
The results shown for estimating the TWA may be one or more of the following:
-The Value of the power estimation, which may be in voltage units.
-Superposition of ventricular repolarization in order to visually identifying alternans.
-The estimated waveform of the alternating wave.
7) Output Interface
It is the interface that transmits information to a user, to another processing stage or a device, about the existence or nonexistence of TWA in the signal.
The proposed designed systems are based on ECG conditions close to the periodicity for detecting TWA. In order to solve the detection problems originated by the lack of synchronization between the window and the signal block due to heart rate variability, the present invention includes an additional modification of the method by applying a standardization process of the ECG signal by truncating of the period. This truncated, changes the frequency components of the signal, but it does not change the temporary information of the alternation.
- Application for detecting ventricular repolarization alternans based on continuous time analysis and the extraction of the information using windowing
Intellectual property status
Current development status
Desired business relationship
The group seeks to achieve commercial cooperation or licensing agreements with companies of Medical equipment and health technology.