[Anticoagulation in pregnant women after artificial heart valve replacement: is low-molecular-weight heparin an alternative?].

We report on the case of a 24-year-old pregnant woman with acute mechanical mitral valve thrombosis due to a treatment failure of low molecular weight heparin (LMWH) for permanent anticoagulation following mechanical valve replacement. Initially, our patient was put on oral warfarin for anticoagulation, but when her pregnancy was perceived the anticoagulation regimen was switched to daily subcutaneous administration of LMWH in order to minimize the risk of warfarin-induced embryopathy. During her 24th week of gestation she developed acute life-threatening pulmonary edema and hemodynamic instability, which was caused by an acute thrombosis of her artificial mitral valve. In an emergency operation the thrombozed valve was replaced by a porcine biological heart valve. The patient recovered uneventfully and gave birth to a healthy child in her 35th gestational week by cesarean section. In addition we discuss the rationale of different anticoagulation regimens with regard to maternal and fetal outcome with special consideration of LMWH as an alternative strategy to oral anticoagulation during pregnancy in women with mechanical heart valves.