DEVELOPMENT OF AN AUTOMATED SYSTEM FOR THE ANALYSIS OF STUDENTS' CARDIAC RHYTHM DURING THE PASSIVE ORTHOSTATIC TEST

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Relevance. Cardiovascular diseases are one of the most common diseases with a high level of disability and mortality both worldwide and in the Russian Federation.
CUQT (long QT syndrome or LQTS – Long QT syndrome) is characterized by dysfunction of the ion channels of ventricular cardiomyocytes, slowing the repolarization of the ventricular myocardium. As a result, there is asynchrony of repolarization of various parts of the ventricular myocardium and, as a consequence, an increase in its total duration [1, 2], which is manifested on the ECG in the prolongation of the QT interval and an increase in its variability.
LQTS syndrome is a potentially life–threatening channelopathy. It manifests itself in prolongation of the QT interval, syncopal states and the development of polymorphic pirouette ventricular tachycardia (TdP – torsade de pointes), which leads to increased risks of SCD.
Syncopal state (SS) is a rapidly developing loss of consciousness with a short duration and sudden termination. According to statistics, more than 30% of the population had at least one case of SS, and 25% have it repeated. Syncope can be detected at any age.
It is believed that SUQT can be congenital and acquired. To date, more than 600 mutations have been detected in 16 genes, which have been divided into 15 LQTS genotypes. It has been established that these mutations can occur in 6 genes of potassium channels (KCNQ1, KCNH2, KCNE1, KCNE2, KCNJ2, KCNJ5), in 2 genes of sodium channels (SCN5A, SCN4B), in 1 gene of calcium channels (CACNA1C) and in 6 genes of specific structural and functional proteins (AKAP9, ANK9, CAV3, SNTA1, CALM1 and CALM2) [3, 4].
Objective: To develop and test a system for analyzing the amplitude-time parameters of a high-resolution ECG.
To achieve this goal , the following tasks were solved:
1. Algorithm development, programming and testing of the ECG parameters analysis system.
2. Registration of high-resolution ECG of student volunteers.
3. Calculation of the amplitude-time parameters of the recorded ECG using the developed automated system.
Materials and methods. The research was carried out on the basis of two laboratories – normal physiology of the VSMU and electrophysiology and functional diagnostics of the Department of FGF of the VSU.
The study involved 40 young volunteers aged 18-19 years.
The methodological basis of the study is "National Russian recommendations on the use of Holter monitoring techniques in clinical practice" (2014), "Clinical recommendations. Ventricular arrhythmias. Ventricular tachycardia and sudden cardiac death" 2020), "Clinical recommendations Acute myocardial infarction with ST segment elevation electrocardiogram" (2020).
Registration of respiration, rheography and ECG of student volunteers was carried out using an electroencephalograph recorder "ENCEPHALAN - EEGR - 19/26" for 5 minutes in each of the positions: horizontal, at an angle of 30 degrees head up (+300), at an angle of 15 degrees head down (-150).
ECG registration in the I standard removal using disposable electrodes Medico Electrodes International Ltc, which were attached to the right and left hand.
The primary analysis of the recorded parameters included the removal of artifact sites and digitization of the recorded ECGs. Using an automated system based on Delphi, separate cardiocycles were isolated in semi-automatic mode, including PQRST complexes. The calculated amplitude and time parameters of ECG waves, the duration of RR and QT intervals were recorded in a text file and subjected to further statistical processing.
The schematic diagram of the automated system developed by us for analyzing the amplitude-time parameters of a high-resolution ECG included several stages:
- reading of digitally recorded ECG parameters;
- visualization of the ECG for each of the leads;
- determination of maxima and minima of P, Q, R, S and T teeth;
- calculation of amplitude-time parameters of ECG teeth and intervals;
- statistical analysis of the amplitude-time parameters of ECG teeth and intervals;
- estimation of variability of RR-intervals and QT-intervals;
- formation of the conclusion.
To graphically reflect a large array of data on the display screen, a Delphi scrollbox component with a horizontal scroll bar was used. A threshold amplitude discriminator was used to determine the maximum point of the R-wave. After determining the maximum point of the R-teeth, cardiocycles were isolated and the extremes of the P, Q, S and T teeth were determined. From the selected extremes, the start and end points of the main ECG teeth were found: Pstart, Pend, Qstart, Qend, Sstart, Send, Tstart and Tend. For automated (software) determination of the beginning and end of the ECG teeth, the moving average method was used, which allows leveling microvolt fluctuations of biopotentials. Thanks to the use of the moving average method, it was possible to implement an algorithm that allows you to automatically determine the end of the T-wave with an accuracy of 0.5 s.
During the variational analysis of cardiointervals, the average values (mean, M) of the duration of the RR and QT intervals, the standard deviation (standard deviation, SD), the coefficient of variation (KV) and the variational span were calculated. The reliability of the analyzed averages was determined using a t-Student.
The results of the study and their discussion. Using the developed automated system, a primary analysis of the registered ECGs of 40 volunteer students was carried out.
It was found that in the horizontal position, the average duration of RR intervals was 921.41 ±51.18 ms (M ±SD), the coefficient of variation did not exceed 5.5%. The time parameters of the QT intervals were characterized by an average duration of 300.49±40.91 ms, KV =13.61%. Orthostatic load +300 in the examined group of students caused a significant moderate increase (p<0.05) in the average duration of RR intervals (decrease in heart rate). The transfer of the examined students to the -150 position, on the contrary, significantly reduced the average duration of RR intervals by 6-8% (p <0.05).
The graphic analysis of the ECG carried out by us clearly showed the electrical heterogeneity of the myocardium of the examined students, which was especially manifested in the variability of the amplitude-time parameters of the P and T teeth and the QT interval.
Conclusion. Using the Delphi object-oriented programming language, a working version of the program has been developed that allows determining and digitizing the amplitude-time parameters of the main teeth and intervals of the electrocardiogram from the ECG recording. Algorithms for finding the extremes of the main ECG teeth using the moving average method have been developed and implemented in machine code. Algorithms for automatic determination of the duration of QT intervals have been developed and implemented in the program, average values of duration and variability of ventricular electrical systole have been clarified. It was found that the passive orthostatic test causes a significant change in the duration of cardiac intervals of the examined students.

About the authors

Anna Alexandrovna Baklanova

Author for correspondence.
Email: bklnv08@yandex.ru
ORCID iD: 0000-0003-2874-2068
Russian Federation, Voronezh, University Square, 1

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