Methods of registration of ECG

Atrial ECG complex consists of the initial part - wave R, intermediate part - segment of the P - TA and final part of The tooth.
Prong P appears when starting the initiation of the Atria, and reflects the processes of emergence and transmission of excitation in the both Atria. The initial part of the tooth R corresponds to the excitation of the right atrium, the middle part is the excitation of both Atria and the end - stimulation of the left atrium.
The shape, direction and amount, and P wave normal ECG in various derivations vary widely.
Value (the amplitude), and P wave, like the rest of teeth, ECG, is determined by the distance from the top isoelectric line, if it goes up, and from the lower edge of the isoelectric line, if it goes down. Measure the tooth in mm; 1 mm corresponds to 0.1 mV in a typical installation of the measuring system.
The length (width), and P wave is determined by the period from the beginning of deviation, and P wave from the isoelectric line before returning it to her. Duration, and P wave depends on the frequency of cardiac contractions; measure it in hundredths of a second; in standard leads ranging from 0.06 to 0.11 sec. (average of 0.1 seconds).
In the chest leads duration, and P wave is sometimes less is 0.06 sec., in esophageal and vnutripolostnyh leads reaches the maximum value (0,12 sec.).

Fig. 11. Electrocardiogram person with a healthy heart in the standard, single-pole breast (GO) and increased unipolar from limb-lead (UE St, University) in an intermediate position in the chest: 1 - right ventricle;
2 - the left ventricle.

In I and II standard leads prong P directed upwards (Fig. 11). Its value in these leads varies from 0.5 to 2.5 mm and is usually equal to 1-2 mm, and in the second abstraction value teeth usually 1.5-2 times more, than in I abstraction.
In III standard lead wave P in the vast majority of cases is directed upwards, and its value is usually equal to the wave P in the second abstraction. But in some cases a normal ECG wave P in the third lead was not isoelectrical), is a two-phase or negative. The largest negative, and P wave is no more than 1 mm
In the first two positions of the chest leads prong R mostly positive, small size (about 1 mm). In the following positions chest leads value, and P wave gradually, but very slightly increases.
In the enlarged single pole lead from the right hand fork R normal negative and in the enlarged single pole leads from the left arm and left leg - positive.
In esophageal leads the shape and direction, and P wave depend on the localization of electrodes in esophageal atrial lead prong P-negative; in esophageal ventricular - dwuhfazno with the first positive phase or positive (Fig. 12).

Fig. 12. Electrocardiogram healthy person in esophageal leads (PS)and - in the sitting; b - in the supine position of the subject. The numbers indicate the distance of the cutting up of olives: 1 - left atrium; 2 - the left ventricle; 3 - right ventricle.

In intracavitary leads the shape and direction, and P wave also depend on the localization of the electrode.
When localization in the upper Vena cava prong R is negative, the localization in the right atrium - dwuhfazno and localization in the right ventricle - positive (Fig. 13).

Fig. 13. Electrocardiogram in intracavitary leads. Differently electrode (entered from the left) in the large veins and cavities of the right atrium and right ventricle: 1 - shoulder Vienna; 2 - untitled Vienna; 3 - superior Vena cava; 4 - the right atrium; 5 - right ventricle; 6 - the lower hollow vein.

Be aware that when you register intracavitary leads, as already indicated, electrocardiograph set at significantly lower sensitivity (1 MB=2 mm).
The segment of the P - TA, corresponding to the period between the depolarization and repolarization fibrillation, sandwiches the next the interval between the end of tooth R and Q-wave and shifted slightly down. To determine the length of the interval P-TA very difficult, because it is difficult to establish the beginning of The tooth.
Prong That reflects the process of the termination of proceedings in the Atria. He merges with the subsequent ventricular complex, sometimes affecting the shape of the segment RS-So Therefore, to determine the form, the direction and magnitude of teeth in physiological conditions is not possible.
The interval P - Q (E), from the beginning, and P wave to the next Q wave, and in its absence - to the beginning of the R-wave corresponds to the period from the beginning of excitation fibrillation before ventricular stimulation, and therefore the period of depolarization of the Atria and the flow of stimulus for wiring system. Excitation fiber wiring system up to its final ramifications receives no reflection on the ECG, most likely due to the fact that emerging EMF is too small. The interval between the end of tooth R and Q-wave sometimes bent and slightly shifted down due to the layering of The tooth. The interval P - Q depends on the frequency of cardiac contractions, sex, age, level of influence at the heart of the parasympathetic and sympathetic departments of vegetative nervous system and varies from 0.12 to 0.21 seconds.