Pseudoaneurysm

A pseudoaneurysm, also called a false aneurysm, is a locally contained hematoma outside an artery or the heart that forms because the vessel wall has been damaged. The injury passes through all three layers of the arterial wall and causes a leak, which is held in by a weak new wall made of the products of the clotting cascade. Because that wall contains no layer of the original vessel, a pseudoaneurysm differs from a true aneurysm, which is bounded by all three layers, and from a dissecting aneurysm, in which the innermost layer is breached and the tunica intima separates from the tunica media. Since it is attached to a vessel it can pulsate and may be mistaken for either. The commonest presentation is femoral artery pseudoaneurysm after access for an endovascular procedure, which may complicate up to 8 percent of vascular interventions. Small ones can clot spontaneously while others need surgery, and a pseudoaneurysm of the left ventricle after a heart attack is a potentially lethal complication.