At the time of autopsy of a 39-yrs-old woman who died of complications of SLE, several medium-sized vegetations are found on both sides of the mitral valve and tricuspid valve. Which of the following is the basic abnormality that produced these cardiac vegetations?

* Plaques or vegetations are found in characteristic locations within the hea in several different disorders. * Vegetations can occur in acute rheumatic fever as small masses found in a row along the lines of closure of the valves. * In contrast, the vegetations of infective endocarditis arc large, irregular masses that extend beyond the valves onto the chordae. Nonbacterial thrombotic (marantic) endocarditis, which is associated with prolonged debilitating diseases and cachexia, may produce one or two small, sterile vegetations at the line of valve closure. In patients with systemic lupus erythematosus, medium-sized vegetations (libman-Sacks endocarditis) may occur on either or both sides of the valve leaflets, typically on the mitral valve and the tricuspid valve. * The development of Libman-Sacks endocarditis is associated with the presence of the lupus anticoagulant (antiphospholipid syndrome), an antibody that makes platelets 'sticky' and increases the chance of thrombosis.