ECG Vector Axis

The measurement method of ECG shaft mainly includes visual method, drawing method and Look-up table method. The following table is a visual method to evaluate the direction of the ECG axis. The heart is a three-dimensional structure consisting of countless myocardial cells. The heart produces many different directional vectors during the polar and repolarization process. Combining the vector pairs of different directions into a vector, the integrated ECG vector of the whole heart is formed. The heart vectors are a three-dimensional, frontal QRS, sagittal and horizontal vectors. Clinically commonly used is the direction of the projection on the frontal surface of the ventricular depolarization process. Help to determine whether cardiac electrical activity is normal.

The frontal QRS electric shaft adopts six-axis system. Coordinates with ± 180 ° angle marking, to the left of 0 °, clockwise to the angle is positive, the inverse bell is negative. Each of the guides is divided into positive and negative halves from the center point, and each adjacent guide is 30 ° between the angles. If the QRS wave frontal QRS the electric shaft falls on the 0~+90 ° for the electric axis normal; 0~-30 ° for the electric axis lightly left bias;-30 ° ~-90 ° for the electrical axis is marked left bias; +90 ° ~+180 ° for the electric shaft right bias; +180 ° ~+270 ° electric shaft extreme right bias.