[Anticoagulation in pregnant women with prosthetic heart valve--a new approach for therapy].

The treatment of women in childbearing age with a mechanical heart valve is a challenge for the medical staff. Warfarin (Coumadin) is considered to be a safe and effective anticoagulant for patients with prosthetic heart valves. However, treatment during pregnancy poses many difficulties, especially during the first trimester, due to its ability to cross the placenta and its associated fetotoxicity. Treatment with heparin during the first trimester decreases the rate of embryopathy, but increases maternal morbidity and mortality. Warfarin therapy throughout pregnancy, which is common mainly in Europe, carries low rates of maternal complications and roughly six percent of embryopathy. Several studies compared warfarin treatment throughout pregnancy versus treatment with heparin during the first trimester. The relationship between daily warfarin doses and the rate of embryopathy was recently investigated. We report two cases of pregnant women with mechanical heart valves who were treated with heparin during the first trimester. Both underwent an emergency replacement of the prosthetic valve during the eighth week of pregnancy. In this article, we review the literature regarding anticoagulation therapy in pregnant women with prosthetic heart valves; the comparison between treatment with warfarin throughout pregnancy and heparin in the first trimester; and the relation of daily warfarin doses with the rate of embryopathy. The two case reports demonstrate the common approach for therapy and the danger within it. In the discussion we present a new approach for treating pregnant women with prosthetic valve and guidelines for the medical staff.