I. Introduction
The electrocardiogram machine can automatically record the bioelectrical signals generated by myocardial agitation during cardiac activity (ECG signals), and it has become a commonly used medical electronic instrument for clinical diagnosis and scientific research.
The electrophysiologic function of the heart and the electrocardiogram are closely and organically related, and many cardiac electrophysiologic malfunctions can be reflected in the electrocardiogram.
The rhythmic and incessant movement of the heart produces a weak electrical signal that is transmitted to all aspects of the human body, and a variety of electrocardiographic signals can be obtained by placing the electrodes of Ergo on any different parts of the human body surface. The ECG leads are how the electrodes are placed on which part of the body and how the electrodes are connected to the positive and negative ECG poles.
Currently, the commonly used ECG leads (i.e., Wilson's network leads) in clinical practice are the standard leads (I, II, and III), pressurized unipolar limb leads (aVR, aVL, and aVF), and thoracic leads (V1 to V6); the less commonly used leads are the bipolar thoracic leads (CC, CL, and CF), the right thoracic leads (V3R, V4R... ...V8R), and V7 to V9 to that, V'1 to V'5 leads, VE leads, S5 leads, atrial leads (A leads), modified CL1 leads (MCL1 leads), "ABC" leads , esophageal lead, atrial lead, and so on.
II. Precautions for placing ECG electrodes:
1. Prepare the patient's skin. Since the skin is a poor conductor of electricity, good contact between the electrode and the skin is important to obtain excellent ECG signals.
--Shave the hair at the electrode attachment site if necessary.
--Wash the electrode attachment site thoroughly with soapy water. The use of ether or ethanol is not recommended as they dry out the skin and increase resistance.
-- Rub the skin vigorously to dry it thoroughly to increase capillary blood flow in the tissues and to get rid of useless skin flakes and skin oils.
2. Place clips or buttons on the electrodes before placing them. If you are using electrodes that are not pre-glued, apply electrode glue before placing the electrodes.
3. Place the electrodes on the patient according to the lead placement scheme you have chosen.
3. Notes on operation and use:
1. If any of the displayed ECG waveforms is too small or clipped, you can change the size of one or all of the ECG waveforms on the screen. Changing the adjustment factor only changes the visual appearance of the ECG waveforms on the screen. It does not affect the ECG signal analyzed by the monitor. To change the size of all ECG waveforms on the screen with a fixed adjustment factor:
--Waveform x0.5 halves the size of the waveform
--Waveform x1 displays the waveform without scaling
-- Amplitude x2 makes the waveform 1x larger
-- Amplitude x4 makes the waveform 4x larger
2. The ECG Filter setting defines how the ECG waveform is smoothed. Filtering reduces interference with the signal. This setting must be used if the signal is disturbed by high or low frequencies.
--50Hz AC interference
--35Hz EMG interference
--100Hz low frequency interference
Lead classification:
1. Standard leads I, II, III
(1) I lead
Left upper extremity electrode is connected to the positive pole of the amplifier input of the electrocardiogram machine, and the right upper extremity electrode is connected to the negative pole of the amplifier
, and the resulting potential is the difference between the two upper extremity potentials. When the left upper extremity potential is higher than the right upper extremity potential, the traced waveform is upward, and vice versa.
(2) II lead
Left lower extremity electrode is connected to the positive pole of the amplifier input, and right upper extremity electrode is connected to the negative pole of the amplifier input. When the left lower limb potential is higher than the right upper limb potential, the traced waveform is upward and vice versa.
(3) III lead
Left lower extremity electrode is connected to the positive pole of amplifier input, and left upper extremity electrode is connected to the negative pole of amplifier. When the left
lower extremity potential is higher than the upper extremity potential, the traced waveform is upward, and downward when prevented.
2. Pressurized unipolar limb lead
(1) aVR lead (pressurized unipolar right upper limb lead)
Left upper limb electrode is connected to the positive amplifier input through a resistor, and the altered central power station is connected
to the negative amplifier input, and the left upper limb electrode and the left lower limb electrode are respectively connected to the altered
altered central power station through a resistor.
(2) aVL lead (pressurized unipolar left upper extremity lead)
The left upper extremity electrode was connected via a resistor to the positive amplifier input, the altered neutral station was connected
to the negative amplifier input, and the right upper extremity electrode and the left upper extremity electrode were connected via resistors to the altered
neutral station, respectively.
(3) aVF lead (pressurized unipolar left lower extremity lead)
The left lower extremity electrode was connected to the positive amplifier input via a resistor, the altered neutral station was connected
to the negative amplifier input, and the right upper extremity electrode and the left upper extremity electrode were connected to the altered
altered neutral station via a resistor, respectively.
3. Unipolar lead
(1) V1 lead: the chest electrode was placed in the fourth intercostal space at the right edge of the sternum.
(2) V2 lead: the chest electrode is placed in the fourth intercostal space at the left edge of the sternum.
(3) V3 lead: the chest electrode was placed at the midpoint of the line connecting V2 and V4.
(4) V4 lead: the chest electrode was placed between the left midclavicular line and the fifth rib.
(5) V5 lead: the chest electrode was placed between the left anterior axillary line and the fifth rib.
(6) V6 lead: the chest electrode was placed between the left midaxillary line and the fifth rib.