"C" stands for "circulation". If the heart stops working, no blood no longer circulates around the body, which is rapidly deprived of oxygen.
During the event, the heart may suffer damage or be detained as a result of shock. May also be sick, as in the case of a heart attack caused by coronary artery thrombosis. Retained cardiac signals include breathlessness, lack of pulse in a particular place of articulation or neck, and dilated pupils.
Trained rescuer will be able to maintain partial circulation via cardiac massage. This victim to have to put on the back, on a hard surface, and regularly put pressure on the bridge. Pressure causes the departure of blood from the heart, located just below the bridge. After relieving the pressure back to the heart fills with blood. This method should be used to change the artificial breathing. However, in some cases does more harm than good. May harm the victim or to stop the work of the heart, which in reality is beating very weakly.