SPR 900 OA ECG Machine is one of the simplest and fastest tests used to evaluate the heart. Certain locations on the chest, arms, and legs are covered with electrodes, which are tiny plastic patches that adhere to the skin. Lead wires are used to connect the electrodes to the ECG device. The heart's electrical activity is then recorded, analyzed, and printed out. No electricity is sent into the body. SPR 900 OA ECG Machine records these impulses to show how fast the heart is beating, the rhythm of the heart beats (steady or irregular), and the strength and timing of electrical impulses as they pass via various cardiac regions.