Collapse and massive pulmonary edema secondary to thrombosis of a mitral mechanical heart valve prosthesis during low-molecular weight heparin therapy.

Mechanical heart valves (MHV) are particularly exposed to thrombosis if anticoagulation becomes ineffective. Thromboembolic complications may be avoided by oral anticoagulation with vitamin K antagonists or derivatives of unfractionated heparin. A few cases of low-molecular weight heparin (LMWH) as sole anticoagulant in patients with MHV have been published, though with contradictory results. We report a case of a massive thrombosis of a St. Jude Medical mitral valve after the patient had been treated for one month with calcium nadroparin (Fraxiparine).