 This is what a normal heartbeat looks like, moments before a sudden cardiac arrest. It can happen anywhere, but you are most likely to be at home. The heart will suddenly stop beating and breathing may be abnormal or stop. Blood won't be being pumped to the brain and other vital organs. It's time to act. Every minute without CPR will significantly reduce their chance of survival. Shout for nearby help and always check for danger before approaching the person. Shout at them and gently shake or firmly tap their shoulders to check for a response. Look and listen for signs of normal breathing. Look for the even rise and fall of their chest. You could put your ear or cheek close to the person's face if you feel safe to do so. If they aren't breathing or not breathing normally, call 999 and explain what has happened. If on a mobile, put it on speaker. The emergency call handler will talk you through how to perform CPR and tell you if there is an automated external defibrillator or AED nearby. Send someone to fetch it, but don't leave the person if you are on your own. If you are concerned about any risk of infection, you could place a cloth over the person's mouth and nose before starting compressions. It's time to give the heart a helping hand. Place one hand on top of the other and interlock your fingers. Place your hands on the center of their chest and begin pushing hard. Aim for two beats per second and do not stop unless someone can take over. You are exhausted, the AED arrives or the emergency call handler tells you to. If an AED arrives, this device can give an electrical shock to help restart the heart. It will talk you through the whole process, so listen carefully to the instructions. Continue CPR until a person shows signs of life. The AED advises another shock or until a paramedic takes over. CPR gives a person their best chance at life. Learn CPR for free by playing Lifesaver at lifesaver.org.uk