Change of a rhythm of cardiac activity.
Electrocardiography allows analyzing changes of a cardiac rhythm in details. In norm frequency of cardiac reductions is 60-80 in a minute, at more rare rhythm - a bradycardia - 40-50, and at more frequent - tachycardia - exceeds 90-100 and reaches up to 150 and more in a minute. The bradycardia is often registered at sportsmen in a condition of rest, and a tachycardia - at intensive muscular work and emotional excitation.
At young men regular change of a rhythm of cardiac activity in connection with breath - respiratory arrhythmia is observed. It consists that in the end of each exhalation frequency of cardiac reductions decreases.
Extrasystole. At some pathological conditions of heart the correct rhythm incidentally or regularly is broken by extraordinary reduction - extrasystole. If extraordinary excitation arises in sinoatrial node during that moment when the refractory period has ended, but next automatic impulse has not appeared yet, there comes early reduction of heart - sinus extrasystole. The pause going for such extrasystole lasts same time, as well as usual. At the person extrasystole can appear at presence of the centers of irritation in the myocardium, in the field of ventricle drivers of a rhythm. The influences acting in heart from central nervous system can promote by extrasystole.
Trembling and blinking of heart. In pathology it is possible to observe an original condition of a muscle of auricles or ventricles of the heart, which are called trembling and blinking (fibrillation). Thus there are extremely frequent and asynchronous reductions of muscular fibers of auricles or ventricles - up to 400 (at trembling) and up to 600 (at blinking) in a minute. As the main difference of fibrillation is non-simultaneity of reductions of separate muscular fibers of the given department of heart. At such reduction of a muscle of auricles or ventricles cannot carry out forcing of blood. At the person fibrillation of ventricles, as a rule, is fatal if immediately to not arrange for its termination. The most effective way of a stop of fibrillation of ventricles is influence strong (a pressure in some KV) the impact of an electric current causing simultaneously excitation of muscular fibers of ventricle then synchronism of their reductions is restored.
The electrocardiogram and VCG reflect changes of size and a direction of potentials of action of a myocardium, but do not allow to estimate feature of force function of heart.
The device and main principles of work of electrocardiograph
Three-channel electrocardiograph with an automatic mode portable ЭКЗТ-12-03 «Альтон» - portable electrocardiograph, allowing operatively to remove the electrocardiogram in various conditions. The design electrocardiograph provides a reliable electrosecurity of the patient and the working personnel.
Electrocardiograph consists of the mainframe, the remote block with a cable of the patient and a power unit.
In the mainframe are located:
The microprocessor block;
Elements of management of operating modes electrocardiograph;
Heat transfer printing,
Indicators of signals and operating modes;
Connection of the ccumulator.
At long storage, accumulator is separated from the mainframe electrocardiograph. For work it is necessary to connect the accumulator shown in fig. 7.
T
urn
electrocardiograph the keyboard downwards. Lower accumulator in a
niche of the case of electrocardiograph so that it overflow on 3 - 8
mm for edge of the case. Densely press the accumulator to a bottom of
a niche. Shift it in a direction specified by an arrow. The latch of
accumulator should come into a deepening of the case and it is
reliable fixed. Turn electrocardiograph so that the latch of
accumulator has appeared above. Be close! At weak fixing the heavy
accumulator can fall, that will lea d to traumas or will cause damage
of the accumulator or a latch.
T
he
remote block of electrocardiograph is structurally executed as a
cable of the patient with protective elements. It is intended for
remove of biopotentials, their transformation to the digital form and
transfer in the mainframe.
CONTROLS and INDICATIONS
In figure the general view of the control panel and indication of electrocardiograph is presented.
Button " Вкл/Выкл " (on/off) serves for switch on and switch off electrocardiograph at the efficient accumulator. At the shone indicator of electrocardiograph it is ready to removal of electrocardiogram. If the indicator blinks, earlier the removed electrocardiograms are kept in memory.
Button "СТАРТ " (Start) switches on and off a mode of removal of an electrocardiogram and press its thermopaper.
If the certain group of taps is chosen, and the mode "АВТОМАТ" (Automat) is switched off, pressing button "СТАРТ" includes continuous record of an electrocardiogram of the chosen group of taps. For a stop of record it is necessary to press this button again.
Button "КОПИЯ" (Copy). Pressing of this button includes a mode of a press of a copy of the last researches, removed in a mode the АВТОМАТ.
In a mode the АВТОМАТ occurs synchronous removal and recording in memory of all of 12 taps. Therefore in a mode КОПИЯ it is possible to print all taps.
Speed, the button "мм/с" (mm/sec), indicators «12,5», «25», «50» - the button of switching of equivalent s peed of development. At consecutive pressing of this button value equivalent speed of development changes. The established value of speed is displayed by the diode.
Group "Масштаб" (Scale), the button " мм/мВ " (mm/mV), indicators «5», «10», «20» - the button of switching of equivalent sensitivity. At consecutive pressing of this button value of sensitivity changes.
Group "Фильтр" (Filter), button "Гц" (Hz), indicators «30», «25» - the button of a choice of frequency of a cut of the filter. If indicators not shine filters are switched off. Pressing button " ", it is possible выбрать frequency at which noise are minimal.
Group "
Смещение
" (Displacement), button «
»
indicators "макс/мин"
(max/min), «среднее»
(average) - the button of a choice of displacement of record of an
electrocardiogram concerning the middle of window of records.
At a printing of a full electrocardiogram taps are grouping: in the beginning taps I, II and III are printed, then - aVR. aVI and aVF are printed; 01, 02 and СЗ; С4, С5 and 06. At a choice of one group of taps on a paper it is deduced only chosen.
Indicators of absence of contact on electrodes connected to extremities have red color; before each registration of an electrocardiogram be convinced that both of the indicators are not shone.
SECURITY MEASURES
To work with electrocardiograph people knowing the operation manual of electrocardiograph are supposed. Electrocardiograph it is protected from dangerous pressure.
PREPARATION OF ELECTROCARDIOGRAPH FOR WORK
Press button «Вкл/Выкл» on the control panel. Thus the indicator of inclusion will light up. Connect the remote block to the core. Insert a cable of the remote block into the corresponding socket.
THE ORDER OF REGISTRATION OF AN ELECTROCARDIOGRAM.