ECG LEADS

Electrocardiographic Electrodes - Sensors that connect to the human body surface to monitor the ECG signal.

Electrocardiographic lead----a circuit composed of any two electrocardiographic electrodes connected to the human body surface.

The standard lead, also known as the bipolar limb lead, reflects the potential difference between the two limbs, 4pcs limb clamp ecg electrodes and 6pcs chest ecg electrodes together use to test the Electrocardiographic

In the 1 lead, the left upper limb electrode is connected to the positive end of the electrocardiograph, and the right upper limb electrode is connected to the negative pole, reflecting the potential difference between the left upper limb (L) and the right upper limb (R). When the potential of L is higher than R, an upward waveform is traced; when the potential of R is higher than L, a downward waveform is traced. In the same 2 leads, the left lower extremity electrode is connected to the positive end of the electrocardiograph and the right upper extremity electrode is connected to the negative end, reflecting the potential difference between the left lower limb (F) and the right upper limb (R). When the potential of F is higher than R, an upward waveform is traced; otherwise, it is a downward waveform. The 3 leads connect the left lower extremity with the positive end of the electrocardiograph and the left upper extremity electrode is connected with the negative end, reflecting the potential difference between the left lower limb (F) and the left upper limb (L). When the potential of F is higher than L, an upward waveform is traced; otherwise, it is a downward wave.

The standard lead only reflects the potential difference between two points on the body surface, and cannot detect the potential change at a certain point. If the negative electrode of the electrocardiograph is connected to the zero potential point (indifferent electrode), connect the probe electrode to any point in the human body. Above, you can measure the potential change at this point. This lead method is called a unipolar lead. Wilson proposed that the three electric potentials of the upper left limb, the upper right limb, and the left lower limb should each pass through a high resistance of 5000 ohms and be connected at a point by a lead wire called the center electric terminal (T). Both theory and practice have demonstrated that the center electrical terminal can be equivalent to the zero potential of the center of the galvanic couple. In fact, the unconnected electrode of the electrocardiograph is connected to the central electrical terminal. The probe electrode is connected to the left upper limb, the right upper limb or the left lower limb of the human body, and the unipolar limb leads (VL) and the right upper limbs of the left upper limb are obtained respectively. Limb lead (VR) and left lower extremity unipolar limb lead (VF).

Because of the small amplitude of ECG waveforms in unipolar limb leads (VL, VR, VF), it is inconvenient to observe. For this purpose, GOLD-BERGER proposes to modify the above-mentioned lead based on the fact that when tracing the unipolar lead electrocardiogram of a certain limb, the high resistance connected between the limb and the central electrical end is disconnected. Increase the amplitude of the ECG waveform by 50%. This lead method is called the pressurized monopolar limb lead and is represented by AVL, AVR, and AVF, respectively. .

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