Mechanical heart valve thrombosis in pregnancy.

Effective anticoagulation is critical in patients with mechanical prosthetic heart valve (MPHV), but remains challenging in pregnancy because both oral anticoagulation and heparins are associated with important fetal and maternal risks. A 33-year-old high-risk pregnant woman presented with MPHV thrombosis during early pregnancy. Resolution of the thrombus and eventual resumption of normal prosthetic mitral valve function was obtained through treatment with low-molecular weight heparin (LMWH). This case of early pregnancy MPHV thrombosis emphasized the importance of adequate initial coagulation prior to pregnancy and the potential need to extend measurements to both peak and trough levels to assure an adequate level of anticoagulation in women with MPHV treated with LMWH during pregnancy.