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.