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Poincaré plot for visualization of the heart rate dynamics
In order to process an ECG with non linear mathematical tools it has to be transformed into a representation which allows a description with mathematics. One of several methods is to use the Poincaré plot representation. For the generation of a two dimensional Poincaré plot two successive R-R intervals ar plottet in an x-y-plane. The first interval on the Y-achses, the second on the X-achses, and so on.
Fig. 1:
Construction of a Poincaré plot. Every two successive R-R intervals are plotted in an x-y plane. Each R-R pair is represented by a point. Due to the natural variation of the R-R intervals, this procedure results in a certain point distribution which represents the individual R-R variation of a person. Usually this is like a fingerprint assuming no changes in the heart condition like a disease or medications.
Example of a Poincaré Plot from a healthy volunteer with a normal heart beat, called sinus rhythm.
Fig. 2:
Poincaré plot for a heart in sinus rhythm. This is an example of a one hour point distribution of a heart in sinus rhythm. As the x- and y- axis have the dimension time, the point distribution shows at one glance the heart rates during the recording. Higher heart rates are represented by the points in the lower left corner, lower heart rates on the upper right.
Mathematics analysis and assesses the heart rate dynamics
Atrial fibrillation is usually recognised in a classical ECG recording by the arrhythmia absoluta, the missing P-wave and an oscillating ECG base line. But this holds only for times the atrium is actually in fibrillation. In addition, the ventricular response of the heart, which represents the dynamics of the R-R intervals, gets irregular. Numerous publications have shown that the irregular response of the heart rate dynamics is often found outside of fibrillation episodes.
Recognition of those periods of irregular heart rate dynamics outside of fibrillation episods is only possible with the help of non linear mathematics. To identify the changes in heart rate dynamics in correlation with paroxysmal atrial fibrillation, a combination of six mathematical parameters and a subsequent comparison with healthy subjects was used. With this procedure, changes in connection with paroxysmal atrial fibrillation could be identified with a high sensitivity.
Before the calculation of the heart rate dynamics, a fully automated cleaning from ECG artefacts and an identification of ventricular beats ensures a correct calculation of the SRA . Identification of ventricular beats is necessary, as they may not be included in the calculation for atrial fibrillation. In the presence of ventricular beats, they will be indicated as other cardiac disrhythmia in the report.
The Report
The user will have the automatically generated SRA report within minutes as a PDF File either via Email or via its personal data base access. The report contains the patient ID and as the result of the analysis, the calculated risk level with the corresponding Poincaré plot, graphical representation of the heart rate dynamics.
The SRA check up is an easy and rapid procedure and requires just a few Steps.
This is shown in a video you can view here.
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