HRV (Heart Rate Variability)
The HRV tab contains the following graphics: ECG, Cardiointervalogram and Scattergram.
ECG
The ECG graph contains the initial electrocardiographic signal of the heart, here the software automatically puts the markers on the peaks of the R-waves. Those places on the ECG that during the recording are indicated by the icon-hearts, after the recording are highlighted with markers – black vertical lines.
The distance between neighboring R-waves is called the RR interval. Each RR interval has a sequential number above it. Duration of this interval is shown in milliseconds next to its number.
On a two-dimensional graph, the horizontal abscissae axis shows the time in seconds, and the ordinate axis shows the amplitude of the heartbeat in microvolts.
The graph can be scaled by increasing or decreasing the amplitude of the ECG at the top left.
The Invert ECG button – inverts the ECG recording in a mirror image.
The Recalculate RR button allows to recalculate RR intervals by changing the threshold value.
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You can also zoom the ECG graph by time by clicking 
at the bottom left.
The recording duration is indicated at the bottom right of the graph.
Cardiointervalogram
Cardiointervalogram is a chart showing the successive changes in the duration of R-R intervals, i.e., it is a graph showing a sequential process of changing heart rhythm measured in milliseconds (MS) – tachogram of the heart. When the heart rate is declining (slowing of heart rate), then the graph is growing up, and increased heart rate leads to the decrease of the curve.
This chart clearly shows both - places of arrhythmias and artifacts - zones where the software was unable to find R-waves automatically due to the presence of high noise level, or a temporary loss of contact caused by the client’s movements.
The software automatically finds zones of arrhythmias and artifacts, highlights them both on the ECGandCardiointervalogram graphs in yellow. To do this, it compares the duration of adjacent RR-intervals and if the length differs by more than 20%, then highlights them in yellow.
In the “VedaPulse® Professional” software manual editing of artifacts is used. With proper preparation to conduct an assessment, the number of artifacts is minimal and there is no a great difficulty editing it if you acquire some experience.
Click with the left mouse button on the found artifact on Cardiointervalogram, it brings you to a segment on the ECG record in the appropriate places for a quick way to edit markers.
A search of the zone requiring editing is easy to make on Cardiointervalogram, and editing of markers is made on ECG.
In order to change the position of the marker hover over the item, press the left mouse button and move the cursor. Then release the left mouse button.
In order to remove the marker, hover over the cursor, press the right mouse button, click Remove R-marker. To insert a new marker, click Insert R- marker.
In order to exclude the interval from analysis (for example, with extrasystoles), hover over the item, press the right mouse button, select Remove RR interval from analysis.
In order to exclude several intervals from analysis (or include to analysis) at a time, click on 
(Multiple RR-marker editing - Exclude RR-intervals from analysis) or 
(Include RR-intervals to analysis). Next, move the cursor over the first R-wave of the range, and, while holding down the left mouse button, select all the intervals that needed to be excluded. Then release the left mouse button. Repeat the above steps again for the next multiple editing.
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— setup scaling according to RR-intervals
Scatterogram
Scatterogram is a correlation rhythmogram consisting of points forming the “cloud”, where each point corresponds to one cardio interval. The distance from the center of the “cloud” and the origin of coordinates corresponds to the Mode (Mo, ms) (most frequently occurring of the duration of RR-interval in the record). The deviation of points from the bisector to the left shows how the cardiac interval is shorter than the previous one, to the right of the bisecting line - as it is longer than the previous one. Thus, consistently estimating the duration of adjacent RR-intervals we form the "cloud".
To understand the physiological meaning of this graph is necessary to proceed from dual models of cardiac rhythm regulation proposed by R. M. Baevsky. This model is based on a cybernetic approach, in which the system of regulation of the sinus node may be represented in the form of two interconnected levels (contours): central and autonomous with direct connect and feedback. Working independent circuit structures of regulation are: sinus node, vagus nerves and their nuclei in an oblong brain (circuit parasympathetic regulation). The respiratory system is considered as an element of feedback in the Autonomous regulation of heart rhythm.
The activities of the central contour of regulation are identified with sympathoadrenal effects on heart rhythm, is associated with respiratory sinus arrhythmia and is characterized by a different low frequency components of heart rate. A direct link between the central and autonomous nervous circuits is performed through (mostly sympathetic) and humoral communication. Feedback is provided by afferent impulses from the baroreceptors of the heart and blood vessels, chemoreceptor and extensive receptor zones of various organs and tissues.
The central contour of regulation of heart rhythm is a complex multilevel system of neurohumoral regulation of physiological functions, which includes numerous links from subcortical centers of the medulla oblongata to the hypothalamic-pituitary level of autonomic regulation and cerebral cortex. The structure of the central loop can schematically be presented as consisting of three levels. These levels correspond not so much anatomical and morphological structure of the brain as certain functional systems or levels of regulation:
- The 1st level provides the organization of interaction of the organism with the external environment (adaptation of the organism to external influences). This includes the central nervous system, including cortical mechanisms of regulation, coordinating the functional operation of all systems of the organism under the influence of environmental factors.
- The 2nd level organizes the equilibrium of various systems of the body between itself and provides inter-system homeostasis. The main role at this level play higher autonomic centers (including the hypothalamic-pituitary system), providing hormonal and autonomic homeostasis.
- The 3rd level provides in-system homeostasis in various body systems, in particular in the cardiorespiratory system (the circulatory system and the respiratory system can be considered as a single functional system). Here the leading role is played by subcortical nerve centers, in particular vasomotor center as part of a subcortical cardiovascular center providing a stimulating or depressing effect on the heart through the fibers of the sympathetic nerves.
In the analysis of Scatterogram, the length and width of the core (without extrasystoles and artifacts) of “clouds” are estimated. The length of the “cloud” reflects the influence of central regulation, and width - of autonomous one.
The normal form of Scatterogram is an ellipse elongated along the bisecting line (see Example No. 4 in the demo version of the software). This location of the ellipse means that the respiratory added some values non-respiratory arrhythmia.
Scatterogram in the form of a circle means the absence of respiratory components of arrhythmia (see Example No. 5 in the demo version of the software).
Narrow, long oval corresponds to the prevalence of respiratory components in the overall rate variability, which indicates a strong mobilization.
The cloud huddled into a small circle (see Example No. 3 in the demo version of the software) shows the reduction of rate variability, which corresponds to strong exhaustion.
At points spaced away from the main group, it is possible to judge about the presence of arrhythmias. The study of Scatterogram is particularly informative in cases when the background of normal cardiac rhythm encountered a sudden disruption and “loss” of individual heart rate. The Scatterogram graph allows to control the presence of artifacts and ectopic foci of rhythm.
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