ELEKTROKARDIOGRAFIYA. At the core of electrical processes lies in the heart of the movement of ions through the cell membrane miokardialnoy. This makes changing transmembrane capacity over the cardiac cycle, which repeats the depolarization (stir with consequent reduction) and repolyarizatsiya (return to the starting point) cells. All myocardial cells electrically active, but only in the cells conducting the system slow depolarization occurs spontaneously, and that determines their ability to automaticity.

Under normal circumstances, arousal is distributed on conductive system and divisions hearts consistently, from sinusno-predserdnogo (sinusovogo) hub, located in the wall right predserdiya and characterized most of automaticity, through myocardial predserdy, predserdno-ventricular (atrioventrikulyarny) node, predserdno-ventricular bundle (bundle Guisa) and of divergence, to the ventricle. In doing so, departments conducting system located distally sinusovogo hub, covered excitation before manifest their own automaticity.

The outer surface of the myocardium instituted on elektronegativna not yet excitations. Thanks to these body tissues of electrical power partly processes can be registered with the placement of electrodes on the surface of the body, where fluctuations in the difference between excitation and potentials nevozbuzhdnnoy parts reach the surface of heart mV 1-3. When recording these fluctuations on the moving paper produced curve - electrocardiogram (EKG), consisting of teeth, repetitive during each reduce heart.

Teeth EKG taken to signify large Latin letters P, Q, R, S, T, U. Zubets R reflects depolarization predserdy, teeth (complex) QRS - ventricular depolarization, zubets T - repolyarizatsiyu ventricles, zubets U, usually malovyrazhenny - presumably repolyarizatsiyu distal segments conductive system ventricles. Teeth, directed upward, considered positive, down - negative. Teeth R, T and U may be positive or negative, always positive zubets R, Q and S teeth always negative, and if they are expressed, located directly in front (Q) or after (S) points R.

To register ECG using special devices - electrocardiographs, with amplifier, DSC galvanometer, recorder.

Comparability EKG achieved through standard conditions of registration. Calmly surveyed lies on his back. Typically, apparatus govern in a manner that tension 1 mV declined arrow to the top 1 cm rectangular shape That label - "calibration" Millivolt - should be at each ECG. With the speed of paper 50 mm / s 1 mm horizontally corresponds to 0.02 (in this case points R width of about 5 mm), at a speed of 25 mm / s 1 mm - with 0.04 (width R points about 2-3 mm ).

Placing electrodes on the surface of the body, their polarity and some technical conditions for registration capability also standardized. In principle for the registration of ECG electrode needed 2, that is Each is like allocating a 2 pole. Using techniques developed "single" of abstraction in which virtually defines the form of ECG fluctuations capacity, with one of the electrodes, called active. Potential from another electrode remains close to zero. Under such a system of registration form EKG increasingly depend on the myocardium, addressed to the active electrode, and thus few opportunities topical diagnosis. Expression of teeth and the ratio of their values vary from aside.

There are currently used, typically 12 ECG: standard - I, II, III; so-called enhanced single from the limbs of abstraction - aVR, aVL, aVF; so-called single-thoracic - V1, V2, V3, V4, V5, V6; on more narrow grounds - other single chest of abstraction, of abstraction for bipolar Nebu (D, A, I). Occasionally apply esophageal (active electrode is placed in the esophagus at the level predserdiya left) and other complementary of abstraction.

When analyzing ECG measures the interval between its elements, are counting the frequency of rhythm, assess the availability, size and shape of teeth in different aside and for that reason be judged on the nature of rhythm, features electrical processes in the heart in general and to some extent - on the electrical activity limited plots the heart muscle. A more rigorous quantitative analysis is possible using a vector theory. Applying this theory in electrocardiography linked with certain assumptions. The difference is the vector potentials, the direction and magnitude of which are constantly changing throughout the cardiac cycle. The spatial representation of the nature of the electrical processes in the heart may be obtained by approximately analysis (with a space teeth) 12 conventional ECG. However, easier and more accurate this is achieved by using specially allocated. In practical work are often limited indication of the position of the electric axis of heart - the vector of the total area of QRS in projection on frontal plane, which, in particular, depends on the situation of anatomical heart in the chest, state intraventricular conduction, the ratio of masses ventricles.

In clinical medicine electrocardiography is the most important in diagnosing cardiac rhythm irregularities. It is important to identify IBS, particularly myocardial infarction, heart attack localization. At the EKG can detect shifts with an increase in heart cells, miokarditah, electrolyte and other metabolic irregularities. The changes reflect a violation of ECG electrical processes in the heart, and they usually are not specific nozologicheski not characterize retractive heart function, may arise not only because of the disease, but also with a substantial violation frequency rate, under the influence of normal daily activity, eating, alcohol, drugs and other causes. Many factors vneserdechnye (emphysema lung fluid in the pleura perikardialnoy and cavities, obesity) contribute to reducing the size of teeth. The structural and metabolic changes in the heart necessary to diagnose not only on ECG, but collectively signs. It facilitates the establishment of a number of ECG diagnosis comparison, has consistently taken at intervals of several days or weeks. Registration is a normal component of ECG BRUY healthy persons.

Informative method significantly increases in long-term continuous monitoring of ECG (even at 1-2 reserved) and conduct functional samples.

For seriously ill (for example, in intensive care units) were observed using bednets kardiomonitorov that permit, in particular, the continual monitoring of ECG. Portable system daily (Holter) monitoring provide continuous recording of ECG on tape during the day in ambulatory conditions, with normal activity of the patient. These systems help detect rare fast emerging and ongoing arrhythmia, provokes clarify the role of external factors, appreciated the aritmicheskogo syndrome and results of treatment. Maybe monitor the shift in ST segment, and thus bezbolevoy identifying ischemia. As vysokoinformativnym, technically relatively simple and neobremenitelnym method for the patient, electrocardiography has found wide application in telemetric control of the state of the working man in professional sports, space medicine. To this end, use special means of imposing electrodes (only on the thorax) and radio communications between galvanometers and recorders.

Of the functional samples from elektrokardiograficheskim control samples from the most common dose of physical stress, especially veloergometriya, which helps determine individual tolerance to stress and substantially increases the sensitivity and specificity of electrocardiography in the diagnosis of IBS. When satisfactory portability initial load the total load of step increases until submaksimalnogo level, which usually corresponds to the frequency pulse 200 minus age (this figure could more accurately define the special tables). Conversion tracking EKG during exercise and during the 6-12 min after loading. Other forms of loads - tredmil, two-stage sample Masters, isometric load - for various reasons, particularly because of the difficulties of dispensing, use less. Contraindications to the use of load tests: acute myocardial infarction, heart failure, expressed violations of rhythm, myocarditis, pulmonary heart, aorta stenosis of the mouth, heart or aorta aneurysm, blood pressure above 200/110 mm Art. Art. Glycosides and beta-blocker cancel a few days before the performance of samples. Among other provocative mention test samples from ergonovinom, which helps in the diagnosis vazospasticheskoy angina. All the samples relate to the character provokes some risk, therefore, should fulfil their experienced staff, with caution, given the contraindications, in the context of preparedness for resuscitation.

Less important are drug samples. For example, in the form of nitroglycerine tablets, the provisions under the tongue, may, through 2-10 min partially remove the EKG changes associated with ischemia, propranolol through 30-60 min after taking 40 mg will eliminate or reduce rather violations arising from the vegetative disregulyatsiey; prednisolone can reduce changes Associated with miokarditom. The specificity and reliability of those samples generally small. Sometimes they can be useful, but not so much to clarify the nature of ECG changes, but rather for the treatment of choice.

Vnutriserdechnaya electrocardiography also applies to elektrofiziologicheskim methods. This invazivnyi method used for specifying the diagnosis arrhythmia and blockades. To this end, the right ventricle heart transvenozno impose catheter with electrodes, which must be pressed to mezhpredserdnoy mezhzheludochkovoy and bulkheads near trikuspidalnogo valve. With such a bipolar allocated separately managed to register signals corresponding to depolarization predserdy, Gisa beam and ventricles. These signals are normally written in such a sequence, time-bound relations among themselves and with elements outside ECG, which always register at the same time. Short-term (for example, for 1 min) frequent (about 150 pulses in 1 min) stimulation programming segments conductive system through electrodes and imposed an additional dimension to follow predavtomaticheskoy allow pause to assess the basic properties of local elektrofiziologicheskie. Vnutriserdechnuyu electrocardiography performed on narrow grounds in the heart of some institutions. In particular, it helps more reliable than a standard ECG, to differentiate levels ektopicheskih arrhythmia and blockades, which is important for the treatment of choice, and detail elektrofiziologicheskie effects of drugs.