Abstract

Introduction

      Cardiovascular diseases, along with cancer and firmly hold primacy among the most widespread and dangerous diseases XX, and now and the XXI century. Rage in the past terrible epidemic of plague, smallpox, typhoid thing of the past, but their place was left empty. New times and new diseases match. XX century with the future of medicine legitimately named "era of cardiovascular disease". Inspires anxiety in the same, and that the incidence of heart disease is constantly increasing and the age of patients is steadily declining. Currently, often when the patient's myocardial infarction age does not exceed 23-25 years. Especially heart disease often occur in men of working age. According to statistics, heart disease in the U.S. annually affect more than 800 thousand man. A similar situation occurs in all civilized countries around the world. Diseases of the heart - a bright example of pathology, course and outcome of which is directly dependent on the timing of treatment to a doctor, timely diagnosis and the start of adequate treatment. Accordingly, the symptoms of these diseases and ways to pre-medical care for heart attack, should be known to everyone, even very far away from medicine. 
     
Scientific research essence  

    The method of investigation bioelectric activity of the heart, known as electrocardiography, is now indispensable in the diagnosis of violations of rhythm and conduction, myocardial hypertrophy predserdy and ventricles, coronary heart disease and other diseases. You can confidently state that the topic is relevant degree work in the field of medicine as well as in programming as razrbotki algorithms decrypt digital signals.

 The graduate work purpose

    Develop a specialized computer system for decoding electrocardiogram rights, with the setting of a preliminary diagnosis. To explore methods and algorithms for decoding ekg rights and you d of major cardiovascular diseases - cardiovascular system.


 The main idea of the work

     The general idea of work can be described as follows: It is necessary to obtain a digital signal, an EKG and to preserve its rights in the database. Then, having set standards, compared with the received signal, to find similarities, differences and deviations from the reference value. According to the deviations try to determine the nature of disease and put predvaritelny diagnosis.

Description

    The method is based on the registration of electrical potentials arising in the heart. The essence of registered cœur, is as follows. Rhythmical reduce operating hearts linked to the spread of its volume electric wave excitation. Therefore, the heart creates around him periodically changing electric field. Cardiogram and is a record of changes in this field. Shocks electrodes to certain points on the human body, we write the relevant projection of the vector, which characterizes the electric field of heart. To get more information about this field as a whole, done a record in several locations or, as doctors say, takes a few ECG. Usually in medical practice is 12 so-called "standard" ECG. Different types of deviations from the norm cœur allow doctor-cardiologist judge those or other cardiac diseases, such as the existence of a heart attack and its localization in the heart muscle. First and foremost, the notion of "normal cœur" quite uncertain. Type cœur depends on small differences in location at the heart of different people, the difference in build and of many other factors that are not associated with any disease. Therefore cœur used for diagnostic purposes necessarily in combination with other signs and in any case requires a doctor making on the basis cœur any conclusion, high skills and much experience. For half a century is well known that the emergence of electric ions through the membrane cardiomyocytes. The high concentration of potassium ions inside the cells or in the extracellular fluid and reduced the concentration of sodium ions inside the cell than outside it, hence the emergence of difference between the building exterior and interior surface of cell membranes. In the rest outside of the membrane has a positive charge, due to high concentration of sodium ions, and internal - is negative, because of the prevalence of cells inside the negatively charged ion chlorine, and other cardiac cells levels of capacity may reach 90 mv and it is called potential of rest. Under the action of various irritant (mechanical, chemical, electrical, etc.) becomes permeable cell membrane for sodium ions, which are due to difference concentrations are beginning to move inside the cells and carry a positive charge there, and the outer membrane surface acquires a negative charge, respectively. This process is called depolarization. After the end of the period excitation cell membrane again becomes less permeable for sodium ions, but more permeable for potassium. Withdrawal of potassium cells prevails over the arrival of sodium in the cell, so the outer membrane surface again gradually becomes a positive charge, and internal - negative. This process was named repolyarizatsii. When the entire outer surface again becomes a positive charge, and vnutennyaya negative, will again be recorded potential rest.[4]


General information about the human circulatory system.

    Vascular system consists of the heart, blood and lymphatic vessels, bone marrow, spleen, lymph nodes. The central organ is the heart of circulatory system, which is a hollow muscular body, consisting of two, the left - and right arterial - venous, halves. Each half of the heart consists of communicating among themselves predserdiya, and heart ventricle. "Predserdiya" take blood vessels from bringing it to heart and ventricles in pushing this blood vessels, claiming it from the heart.

Pic.1. Human circulatory system. .

      Under the direction of movement of arterial and venous blood vessels to distinguish arteries, veins, and capillaries connecting them. The walls of arteries and veins are composed of three layers: the inner lining, the average envelope, and the outer casing. The inner hull vessel, consists of soedinitelnotkannoy basis, subendothelial and endothelial cells; yr subendothelial layer rostkovogo play a role, endothelial - vystilayut inner surface of the dish. Average shell, or muscle, formed mainly located circular smooth muscle fibers, as well as soedinitelnotkannymi and elastic elements. The outer shell consists of collagen fibers and a number of longitudinal beams elastic fibers. In the structure of the walls of arteries and veins there are differences. Wall veins thinner walls of arteries, veins muscular layer of a rudimentary. In the veins, especially small and medium-sized, there are valves. Depending on the degree of development of muscle or elastic medium shell elements distinguish the type elastic artery (aorta, pulmonary trunk), muscular-type elastic (sleeping, femur and other artery of the same calibre) and the muscular artery type (all other arteries). The walls of capillaries consist of a single layer of endothelial cells. Caliber and the wall thickness of blood vessels as their removal from the heart "as a result of dividing the organs and tissues of the body changing. In each organ of branching vessels, their architectonics, have their peculiarities. Outside - and vnutribryushnye vessels, connecting with each other, form a fistula, or anastomosis; branches connecting with each other vessels, are called anastomoticheskih vessels. In some places anastomosis between vessels so numerous that form the arterial or venous vascular network, or vascular plexus. With parallel vascular stem, anastomosis connect his plots, more or less distant from one another, as well as blood vessels in organs and tissues. Vessels taking part in the formation of collateral circulation - collateral blood vessels, can restore blood circulation in some parts of the body with blood on the difficult traffic trunk. Besides anastomoses, the artery connecting with the arteries and veins to veins, there are connections between arteries and veins, arteriovenous anastomoses in which blood from arteries directly goes into the vein (fingers of the hand, kidney capsule). Arteriovenous anastomoses form a so-called blood circulation apparatus acronym - derivatny apparatus. In some places arterial and venous system has a network of blood She is a network of capillaries, which provide a stable and judge vessels, such as in vascular klubochke kidneys, which brings arterial vessel is divided into capillaries, which again gather in arterial vessel.[4]

The method of recording ECG

     For quality ECG should be observed some general rules for its registration. ECG recorded in the heat indoors, isolated from potential sources of electrical interference, in 10-15 min rest patient, no earlier than 2 hours after eating. Record EKG conducted usually in the position of a patient lying on his back, with a maximum of muscles and relaxing them quiet shallow breathing. At the inner surface of the lower third of drumsticks and forearm packs and electrodes fastened (metal plates), on the chest electrodes fastened pears - suckers. For better contact with the skin of its desirable degrease alcohol and slurred special electrode paste or use gauze pads, wetted fizrastvorom. In place of large fibrous skin contact wetting soap solution. To connect the wires from the electrodes electrocardiographs with the appropriate color markings. Generally be marked as follows: the right arm - red, the left - yellow, the right leg - black (earthing), the left - green, chest electrode - white. Before recording ECG electrocardiographs establish channels for strengthening the same electrical signal (calibration mV). Generally regulate this signal in such a way that caused tension in ImV rejection of the registering of 10 mm. The signal, if necessary, you can increase or decrease. Then spend record ECG in 12 different aside, consistently placing handle the switch to the appropriate position. In each allocated a record of at least 4 EKG complexes at speed paper tape, typically 50 mm / sec. The smaller speed - 25 mm / s, 12.5 mm / s - applied in the diagnosis of violations of rhythm. With the speed of 50 mm / s for each small cell lines (1 mm) interval corresponds to 0.02. ECG systems EKG Plot body surface, which impose electrode, called the position electrode. Two any position electrode, which for the period between the initiation of heart reveals the difference potentials, are two electric poles to record ECG. Each pair of poles through which the galvanometer writes voltage, called EKG-aside. Eynthovenom (1908) showed that for the evaluation of direction is required to compare several ECG (minimum two) ECG with certain characteristics. The complex is similar ECG so-called ECG system. Properties do so is equidistant from the heart of electrodes, little sensitivity to small mixing ECG electrodes, equality ECG axis between themselves and their dominance over the length of the size of heart. In clinical electrocardiography classical geometric ECG system is considered to be developed for Eynthovenom frontal plane "scheme equilateral triangle". Eynthoven selected for the formation of three ECG electrodes on two hands and left leg and united in pairs these positions, proposed that data on the part of abstraction as an equilateral triangle, which is located in the heart of the heart. In doing so, such a connection with electrodes poles galvanometer (polarity ECG), in which each of the three main elements of a normal ECG ECG (teeth R, R, T) recorded izoelektricheskoy top of the line when the values of the right hand negative towards the top of the heart or his left hand, a positive potential zone of body surface connected to the positive pole galvanometer. EDS is changing direction in the process of stimulation, but ultimately the EDS directed downwards, from right to left, rear advance. Thus, the upper half of the body (the right arm, head and neck) has a negative potential, and the lower left half (both legs, left hand) - the positive potential. There are currently 12 major ECG is used. Pairs of electrodes, imposed on the limb, in turn connects to the apparatus. On the right hand impose electrode with red marks on the left - with the yellow on the left leg - with green on the right leg - to connect with black earth wires. [1]


Pic. 2 Scheme of axes in the frontal plane of abstraction. 1 - Eynthovena triangle, 2 - System axes Bailey
(animation 14.8Kb, 4 frames, delay 2s, Repeat count 10)

Axes standard ECG Eynthovenu to portray in an equilateral triangle, whose center - the source of EDS.

I allocating - the right arm (-) - left hand (+) Allocating
II - the right arm (-) - left leg (+) Allocating
III - left hand (-) - left leg (+)

Enhanced single limbs of abstraction with Bailey.

AVR - combined together electrodes on the left arm and left leg, and potentials removed from the right hand (+)
AVL - combined together with electrodes right hand and left foot, and potentials removed from the left hand (+)
AVF - combined together with electrodes right hand and left arm, and potentials are removed from the left leg (+)
Axes reinforced unipolar ECG located between the axles standard ECG The system Ose All ECG axis of limbs are located in the vertical plane. According to Bailey axes we can determine the situation in the heart EDS frontal plane. [2]

Filtering noise in ECG

        Major sources of interference in the registration EKG taken to separate at high: biological origin - miogramma; fire rounds of equipment - Noise 50 (60) Hz; "throws" isolines; rapid change capabilities polarization electrodes - "throws" isolines; registration artifacts. Low - slow-building changes the polarization of electrodes - drift isolines.
A comparison of the impact of several kinds of filters at lower frequencies EKG shows that with almost identical characteristics, but different implementation of filters can be obtained fundamentally different effects. Filter the lower frequencies, typically results in lower amplitude QRS-complexes, but technically possible to make a filter that will set QRS, on the contrary, stretch. Both are not conducive to the quality of diagnosis. The duration of the same set of QRS options under any filter seeks to expand, but in one case, it will be 13%, and in another - 30%, and this can not be ignored. It should be noted that ADS virtually no influence on the shape and position of segment ST. Job ADS accompanied by only a small delay between when the ECG and its conclusion. Concluding section filtering ECG, one can not help but remember that filtering might affect the amplitude, duration and teeth shift intervals EKG; comparable results for the records should always strive not to use filters; when interpreting ECG should be taken into account, whether filtering, and what degree its impact on the diagnostic criteria; simple empirical evaluation of a specific filter apparatus is possible by recording several ECG with filters and without them, in comparing several ECG should take into account the possible impact of filters.[2]

Analysis EKG 

     At stage computational analysis to create a table amplitude-time characteristics of all elements of ECG with codes configuration forms teeth (PI, P2, Q, R, S, Rl, Sl, Tl, T2, Jv, ST, FP, FST, FT, PQ, QRS , QT). Moreover, 40 - seconds recording identifies statistical characteristics RR-intervals. Registration is automatic detention - in the form of interpreting ECG machine, as elektrofiziologicheskogo sindromalnogo imprisonment (for an adult or child), which is presented in the customary form for the doctor. The interpretation of ECG contains opinion on the contour and rhythm, using more than 100 elementary conclusions. Nomenclature conclusions based on the existing methodological recommendations, consists of opinions dictionary (key terms), according to the requirements set out by WHO, and includes 10 diagnostic classes. A diagnosis of heart rhythm irregularities, myocardial infarctions, (including stage and localization 'overall), pencils Gisa blockades and other violations of conductivity (including blockades AV-compounds), hypertrophy, etc.; Doctor given an opportunity to verify and edit the conclusion. The system provides work with the archive, stored in the archives as automatic interpretation, and formed Medical conclusion. The system allows to display curves, the previously recorded, and to assess the dynamics of ECG overlaid curves, recorded at different times. The Archives holds the record of one observation on the disk volume of about 20 kilobytes. The disadvantages system can be attributed tough assignment of the survey methods and limited computational analysis of ECG. [3]

Conclusion

      All ruzultaty obtained in lifting electrocardiogram in the future to varying degrees, will contribute to the diagnosis doctor. The accuracy of the results will depend solely on the characteristics of the equipment used and the choice of signal processing algorithms. At the moment there are 2 basic EKG decryption algorithm. The first of algorithms based solely on medical logic, that is actually interprets actions doctor - dagnosta, and is the most simple in terms of programme implementation. The second algorithm is based on methods of mathematical statistics and probability theory. Both of these algorithms have their advantages and disadvantages: 1 algorithm may limit the hardware, the second requires some accuracy in processing the data used in the diagnosis. Yet both the algorithm are relevant and should be used when developing complexes for the diagnosis of cardiovascular diseases rights.


Literature

1. Articles for doctors
    Source: http://esus.ru/php/content.php?group=257

2. Information portal for Cardiology:
    Source: http://www.ecg.ru


3. Allocation of QRS-complexes in ECG computer systems
    By: V. Nagin, I.Potapov,S. Seelichev
    Source: http://masters.donntu.ru/2001/kita/rybalova/diss/lib/qrs.html

4. Big medical encyclopedia (electronic version 2005 on CD)