ECG connections (ECG leads) are the limb leads and chest leads that are connected sequentially to the appropriate parts of the body. ECG leads are circuit connections where electrodes are placed on different parts of the body and connected to the positive and negative terminals of the EKG machine’s ammeter via lead wires. A typical ECG machine has four limb leads and six chest leads. The limb lead probing electrodes have 4 colors, and their placement is as follows: red electrode is located at the wrist of the right upper limb, yellow electrode is located at the wrist of the left upper limb, green electrode is located at the ankle of the left lower limb, and black electrode is located at the ankle of the right lower limb. The thoracic leads include leads V1~V6, and the positions are: V1 at the fourth rib end of the right sternum; V2 at the fourth rib end of the left sternum; V4 at the intersection of the fifth rib end of the left sternum and the clavicle centerline; V3 in the center of the straight line connecting V2 and V4; V5 at the same height as V4 and at the intersection of the anterior axillary line; and V6 at the circumferential height of V4 and at the intersection of the mid-axillary line. Specific ECG operation connection needs to be carried out by professional physicians, if the operation is wrong, it can cause inaccurate results and affect the judgment of the condition.