The heart is a three-dimensional structure. In order to reflect the electrical activity of different sides of the heart, electrodes are placed in different parts of the human body to record and reflect the electrical activity of the heart.
The measurement methods of ECG axis mainly include visual inspection, drawing and table lookup. The following table is the ECG axis direction evaluated by visual inspection. The heart is a three-dimensional structure, consisting of countless myocardial cells. In the process of depolarization and repolarization, the heart will produce many electric coupling vectors in different directions. The electric coupling vectors in different directions are integrated into a vector to form a comprehensive ECG vector of the whole heart.
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Extended data
The principle of ECG generation
The myocardial cell membrane is a semipermeable membrane. At rest, a certain number of positively charged cations are arranged outside the membrane, and the same number of negatively charged anions are arranged inside the membrane. The potential outside the membrane is higher than the potential inside the membrane, which is called polarization state. At rest, because the myocardial cells in all parts of the heart are polarized and there is no potential difference, the potential curve recorded by the current recorder is straight, which is the equipotential line of the body surface electrocardiogram.
Different wires are formed between the two electrodes or between the electrodes and the central potential terminal, which are connected with the positive and negative electrodes of the galvanometer of the electrocardiograph to record the electrical activity of the heart. A bipolar wire is formed between two electrodes, one of which is a positive electrode and the other is a negative electrode.
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