Methods of registration of ECG

Ventricular complex consists of the initial part of the QRS complex, intermediate part - segment RS-T and the end part - prong So
The QRS complex reflects the gradual coverage of excitation of both ventricles. The size and shape of the teeth of the QRS complex vary considerably in different leads and change with the position of the heart in the chest.
To determine variations in the size of a teeth of the QRS complex use of notation, in which the teeth of the great values are denoted by capital letters, and the teeth of a small value is lowercase.
Rarely in physiological and most of the pathological conditions of the QRS complex has an extension teeth. In cases, when the R-wave should directly upward spike, denoted as R'; if R' should downward spike, denoted as S'; if in the initial part of the QRs complex, there are, in addition to these R' S', extra teeth, they are respectively denoted R"S" (Fig. 14).

Fig. 14. Designation of teeth of the QRS complex.

To determine the magnitude of the QRS complex as a whole determine the value of each individual tooth; the value of the upward R-wave is considered positive with a plus sign and magnitude aimed down teeth, Q and S - negative (with a minus sign). The algebraic sum of all the prongs of the QRS complex characterizes its value as a whole.
When determining the size of a teeth of the QRS complex should be taken as the reference level interval P-Q in the point, where the rate goes Q wave, and in its absence - in the R-wave
The QRS duration is determined by the period from the beginning of the deviation of Q-wave from the baseline to reach this line ascending knee prong S, and in the absence prong S - to reach this line downward knee R-wave and in norm fluctuates from 0,09 0,06 to sec.
The QRS complex has sometimes in different leads isoelectric initial and final part. Therefore, the QRS duration should be measured in the abduction, in which the most of it.
The super Q is the first downwards prong initial part of the QRs complex and corresponds to the period of coverage excitation of the interventricular septum and right papillary muscles. The tooth is often missing.
Value (amplitude) zubza Q (the distance from the lower edge of the baseline to the bottom tip of the tooth) normal ECG does not exceed 1/4 of the subsequent wave R.
The length (width) Q wave measured at the level of the upper edge of the baseline or point and is determined by the period from the beginning of deviation wave down until it reaches the level of the upper edge of the original line. Normally the duration of super Q less than 0.03 sec. In standard leads the Q-wave is more likely to occur in II and III leads, at least I lead.
The R-wave - usually the largest upward spike ECG and corresponds to the period of gradual coverage of excitation of both ventricles. When the downward elbow R-wave reaches the middle, agitation covers the whole heart. Value (amplitude) of the R-wave is determined by the distance from the intersection Q wave with the source level (without zubza Q - top-baseline) to the top of the R-wave Magnitude varies from 1 to 24 mm
In II standard lead the value of the R-wave usually the highest and reaches 24 mm. In the chest leads in first and second position value of the wave is small, then up to the fourth position, it gradually increases in the fifth and sixth positions decreases.
The interval from the start of the Q wave to the top of the R-wave corresponds to the most prolonged period of excitation through the maximum thickness of the right or of the left ventricle and is defined as the time of occurrence of the internal deviations. Usually this period is equal to 0.02 seconds. In the left chest leads the time of occurrence of the internal deviations less than 0.03 sec., and in the left-0,045 sec.
With two peaks - R and R' - time internal deviations are determined up to the top of the R-wave, which has the largest downward knee.
Prong S is downward spike initial part of the QRs complex. The downward elbow prong is a direct continuation of the downward bend R-wave Rising knee teeth usually more flat. The isoelectric point on the line of transition prong S in the segment RS-T is defined as a connection (junction). Prong S corresponds to the period when both ventricles covered excitation. Value (amplitude) - wave is determined by the distance from the intersection of the descendant of the tribe of the R-wave with the initial level to the lower tip of the tooth and ranges from 0 to 6 mm
Prong's usually absent in I abstraction and is more likely to occur in II and III leads. In the chest leads prong S has the largest value in the 1st position, then gradually decreases and in the 5th and 6th positions often missing.
Segment (interval) RS-T (R-T) - intermediate part of the QRs complex, corresponds to the period when the intensity of excitation, covering both ventricle begins to fall. In the period corresponding to the end of the segment, the process of termination of ventricular excitation.
Segment RS-T is usually on the isoelectric line, sometimes slightly offset, down more often, rarely up.
When determining the degree of offset segment, as and when determining the size of a teeth of the QRS complexes, should be taken as the reference level line interval P-Q in the point, where the rate goes Q wave, and in its absence - in the R-wave
The duration of the segment RS - T varies widely, mainly depending on frequency of cardiac contractions.
Prong T - upward spike with sloping slightly concave upward knee, a rounded top and steeper downward knee. Thus, the asymmetric wave, and the top of it is closer to the end than the beginning of wave. Prong reflects the process of termination of ventricular excitation - repolarisation. The direction, the form and the size of the T wave are defined in the same way as wave R. the Value of the T wave is usually 1/2 - 1/3 of the R-wave
In standard leads the tooth T always positive in the first abduction and in overwhelming majority of cases in the second abstraction, in the third lead was it positive or dwuhfazno or negative (in 25% of cases). In the chest leads the tooth T usually positive. In the 1st and 2nd positions and sometimes very seldom in 3rd position is negative. The size of the tooth is usually gradually increased to 4-th Position, and then gradually decreases. In lead aVF (UE) prong always negative, as in the rest of the leads from the extremities can be both negative and positive. The length (width) of the T wave (the period from the beginning of the rising knee before the end of the downward) varies within wide limits (from 0.05 to 0.25 sec.).
The termination process of excitation is more labile than the appearance of it. This explains that tooth T more influenced by different factors.
Cut Q-T (from the beginning of Q-wave till the end of the T wave) corresponds to the period from the beginning of ventricular depolarization heart until the end of their repolarization - electric systole heart. The duration of a segment of the Q - T depends on the duration of the cardiac cycle, i.e. the number of heartbeats in 1 min.
To determine the relationship between the length of the segment of the Q-T and cardiac cycle duration in General, a healthy person proposed various formulas. The most accurate was the formula, according to which the duration of a segment of Q-T the norm is equal To the· & Radic; p, where K is a constant equal to men 0,37, and for women to 0.39, p - cardiac cycle duration, expressed in seconds.
For characteristics of the electric systole you can use systolic indicator of Fogelson and Chernogorov, representing the percentage ratio of the duration of the electric systole, measured along the segment of the Q-T for the duration of the cardiac cycle.
Comparing the values of systolic indicator has its value, it is possible to judge about the function of the myocardium.
Prong U is occasionally observed upward spike that follows the tooth T usually at intervals of 0.04 sec. Prong U Mal, rising in his knee more steeply than the downside, the tip is usually rounded and considerably less pointed.
Prong U most authors consider both the potential aftereffects. However note that it coincides with a period of increased excitability of the ventricles in the early diastole. The Genesis wave linked to other factors; elastic relaxation ventricular muscles in the early diastole, potential stretch of the aorta, etc.