Application: It is used to extract the human electrocardiographic wave group for morphological and rhythm analysis for clinical diagnosis and research.

Eighteen-lead ECG refers to the conventional chest lead on the basis of the twelve-lead ECG Ⅰ, Ⅱ, Ⅲ, avR, avL, avF, V1, V2, V3, V4, V5, and V6. Extension as a theoretical basis, extending three leads to the left and right each to form a synchronized eighteen-lead ECG system consisting of six limb leads and twelve chest leads. The specific method is: lead V7, V8, and V9 are derived at a certain angle to the left and rear based on lead V6 to detect the myocardial ischemia and injury of the posterior wall of the left ventricle; based on lead V1, Three leads, V3R, V4R, and V5R, are derived at an angle from the right rear to detect right ventricular myocardial ischemia and injury. The 18-lead ECG lead system is based on the classic ECG secondary projection theory, based on the correction of the Frank lead system, and a series of corrections are made to the steering axis angle of the leads as needed (about the ECG vector generated Basic theory and the basic principles and application methods of the Frank system).