What is the Difference Between a Thrombus and an Embolus?

What is the difference in a thrombus and an embolus? They both have one thing in common, they are both usually blood clots; but, the thrombus is stationary such as a deep vein thrombus in the thigh or a popliteal thrombus behind the knee.

An embolus is a thrombus that has moved from one place to another. You might hear such medical slang as, "he's thrown a PE". This translates into a thrombus moving from one location to a lung; thus, the "PE" or pulmonary embolism.

A clot can also form in the heart itself with mitral valve regurgitation, or atrial fibrillation. Atrial fibrillation is where the top part of the heart; the smaller chambers called the atrium begin to quiver rather than pump effectively. Blood that isn't moving tends to congeal, forming clots. These atrial clots can migrate to the ventricles where they can be "thrown" to another part of the body, such as the brain, causing a stroke. Mitral valve regurgitation occurs when the atrium finishes pumping blood to the ventricle. The mitral valve is supposed to close tightly in order to prevent contraction of the ventricle from pushing blood back into the filling atrium. If the mitral valve has a slight leak, blood can be forced back into the atrium. This problem can be repaired with surgery.

A similar situation can result with congestive heart failure in an advanced condition. This situation causes the ventricles to empty ineffectively; leaving some residual blood that can clot and go to another part of the body; or, the heart itself. The heart is fed by vessels that come off the aorta. As the heart pumps, some of the blood goes to vessels such as the anterior descending coronary artery. If a clot winds up in one of these arteries that feed the heart, a "heart attack" can occur, depriving certain portions of the heart of oxygen and nutrients. You may hear this referred to as a myocardial infarction or coronary occlusion. These situations are very dangerous, but not necessarily deadly. There are many variables involved; primarily, if the clot can be broken up or the amount of muscle damage that occurs. The first two weeks of a myocardial infarction are critical times.

If you have a thrombus; say, in your leg; do not rub it under any circumstances whatsoever. Take your medication religiously; the doctor may have you on blood thinners and possibly antibiotics for cellulitis that could form around the clot. If you take care of yourself and follow your doctor's orders; there is no reason that the thrombus can't dissolve on it's on and never become an embolus that would threaten your life.