A coronary thrombosis occurs when an artery in the heart is blocked by a thrombus, or blood clot. It is a variety of ischaemic — meaning involving lower blood supply — heart disease. The condition can lead to a myocardial infarction, most commonly known as a heart attack.
As humans age, their once smooth and open arteries begin to harden and thicken in a process called atherosclerosis. The walls of the arteries can also begin to accumulate a fatty substance known as atherosclerotic plaque. Once it has adhered to the walls of the arteries, the plaque begins to harden. These changes shrink the pathway for blood and slow its progress through the arteries.
When blood flow begins to slow, it can start to clot. These clots are called thrombuses, and the process by which they form a blockage in the arteries is thrombosis. When this process takes place in the arteries that lead to the heart it is called coronary thrombosis.
Blood clots can accumulate in the arteries in a couple of ways. In some instances, a thrombus travels slowly through the blood stream, accumulating new matter until it is so big it becomes lodged in the artery — either obscuring most of it, or blocking the passage entirely. Blood clots can also form around the hardened growths that line the arteries and expand until the passage is closed off.
Though coronary thrombosis is often thought to be interchangeable with heart attack, the two are distinct events. The heart attack is only a possible outcome of the blockage caused by coronary thrombosis. If the condition is treated in time, a heart attack can even be avoided.
When coronary thrombosis blocks off an artery, blood flow stops to a specific portion of the heart. Without fresh blood, that piece of heart muscle dies. The severity of this event depends on the size of the blocked artery.
If coronary thrombosis closes a small artery, the other arteries that flow to the heart may be able to compensate for the loss of blood in one section. For this reason, coronary thrombosis can be more easily treated, and a heart attack averted, if the blockage is in a smaller artery. A larger blocked artery is more difficult to compensate for and is often the kind involved in a heart attack.
Though a mild coronary thrombosis can be treated, once it has occurred the chance of a recurrence is greatly increased. The portion of the heart that has died as a result of the incident poses a great health liability. Anti-coagulant drugs are typically prescribed in order to reduce the risk of another blockage.