The heart is surrounded by three major coronary arteries that supply it with blood and oxygen. If a blood clot develops in one of these arteries, the blood supply to that area of the heart muscle will stop. This is known as a coronary thrombosis, a myocardial infarction or heart attack.

Most commonly a coronary thrombosis will cause severe chest pains behind the sternum (breast bone), often radiating towards the left arm. The area of muscle to which there is insufficient supply stops working properly if the blood clot is not dissolved quickly, eg with thrombosis dissolving (thrombolytic) medication.

The typical symptoms are:

• spontaneous pain behind the sternum (breast bone) or the front of the left-hand side of the chest.
• a possible radiation of the pain towards the left arm.
• the pain can also radiate towards the hands, jaw, ear, stomach or the right arm.
• a constricting sensation in or around the throat.
• there can be severe and spontaneous breathing difficulties with or without pain.
• sudden fainting or severe dizziness, often accompanied by pain.