Mitral-valve prosthesis, warfarin anticoagulation, and pregnancy

The course of pregnancy in patients with artificial heart valves treated with dipyridamole

Continuing improvements in cardiac surgery and a wider selection of young patients for prosthetic valve replacement mean that an increasing number of women of childbearing age will undergo such procedures and will also subsequently become pregnant. At present, most patients with prosthetic heart valves are treated with anticoagulant drugs for life. The main problem with anticoagulant therapy during pregnancy is fetal and maternal hemorrhage. Congenital anomalies have been described in infants born to mothers treated with coumarin derivatives during the first trimester of pregnancy. Dipyridamole is known to decrease the adhesiveness of platelets or their ability to aggregate. We report the successful outcome of four pregnancies in patients with Starr-Edwards prostheses who were treated with dipyridamole during their pregnancies.

Maternal and fetal sequelae of anticoagulation during pregnancy

Review of published cases of pregnancies in which coumarin derivatives or heparin were administered demonstrates that use of either class of anticoagulant carries substantial risks. Of 418 reported pregnancies in which coumarin derivatives were used, one-sixth resulted in abnormal liveborn infants, one-sixth in abortion or stillbirth and, at most, two-thirds in apparently normal infants. In addition to the expected hemorrhagic complications, fetal effects of coumarin derivative administration include a specific embryopathy and central nervous system abnormalities. All available cases (including unpublished ones) of warfarin embryopathy and central nervous system abnormalities following gestational exposure to coumarin derivatives are reviewed, various complications are tabulated, critical periods of teratogenesis are discussed and possible mechanisms proposed. The use of heparin during gestation does not result in a significantly better outcome of pregnancy. In 135 published cases, the infants in one-eighth were stillborn, in one-fifth premature (a third of whom died) and, again at most, in two-thirds apparently normal. Because of the substantial risks of both clases of anticoagulants, and the inherent risks of pregnancy complicated by the indications for anticoagulation, prevention of pregnancy is usually indicated. If pregnancy occurs, a relatively normal outcome can be anticipated in about two-thirds of the pregnancies regardless of the anticoagulant used. Heparin does not appear to be a clearly superior alternative to coumarin derivatives.

The management of anticoagulant therapy during and after pregnancy

Fifteen patients were treated with oral anticoagulants during pregnancy. At 37 weeks they were changed to heparin and were given 5 mg of Vitamin K1 by intravenous injection. Labour was induced seven to ten days later. All infants were normal and healthy and in the 12 tested the cord prothrombin times were within the normal range.

Management of anticoagulant therapy during pregnancy in patients with prosthetic heart valves

We describe two patients with Starr-Edwards mitral valve replacements who underwent pregnancy on oral anticoagulants and who were successfully delivered of live babies. The literature on pregnancy with prosthetic heart valves is reviewed. It is suggested that properly controlled oral anticoagulation should be continued until the onset of labour; the anticoagulant effect should then be reversed by an intravenous infusion of fresh-frozen plasma and the patient maintained on intravenous heparin injections six-hourly. Oral anticoagulants should be restarted immediately after delivery and the heparin withdrawn only when their effect has been re-established.