Pregnancy in patients with cardiac valve replacement has been reported to carry an extra risk for mothers and a high fetal mortality. Most patients reported in the literature had mechanical valve pros-theses and oral anticoagulation therapy during pregnancy. Thromboembolism was the main cause of maternal mortality and morbidity. The main cause of fetal mortality has been the use of oral anticoagulants. Antivitamin К derivatives produce fetal hemorrhages and have a direct teratogenic effect upon the fetus mainly in the first trimester of pregnancy. A great number of abortions, stillbirths, neonatal mortality, and congenital malformations are due to the use of any warfarin derivative taken during pregnancy.
From 1975, we have been using aspirin for prevention of thromboembolism after bioprosthetic valve replacement. The 20 patients studied here were all treated throughout the pregnancy, delivery, and postdelivery period with this medication. Data from our study show no maternal mortality or morbidity in any of the 27 pregnancies. The abortion rate is similar to the abortion rate of the general population attended to in our hospital and to the abortion rate of the same patient group before cardiac valve replacement. There were no stillbirths, perinatal mortality, or malformed babies. The rate of forceps deliveries and preterm infants is also within the normal range of our general population (Table 1).
All patients dealt with the cardiovascular overload of pregnancy with no difficulties. Digitalis and diuretics were given according to the needs of each individual woman.
This study confirms the data of published case reports and of a collective study. Patients with tissue valves and no anticoagulation therapy behave similar to normal pregnant women. Oakley and Doherty have reported 18 patients with tissue valves and no anticoagulation therapy. There was no maternal mortality. One patient had brain embolism. There was no infant mortality and only one abortion and one infant with harelip.
The patients in our series were particularly prone to thromboembolism because 14 of them had mitral valve replacement (seven had double valve replacement) and 13 experienced atrial fibrillation. There was no single case of thromboembolism in the entire series. We have described a low thromboembolic rate after valve replacement with bioprosthesis when patients were treated with aspirin. Patients with mitral and double valve replacement in atrial fibrillation had a lower thromboembolic rate when they were treated with aspirin than when treated with oral anticoagulants. From the present study, it is concluded that women of childbearing age who wish to have children should have their valve replaced with a tissue valve. Pregnancy in this situation will be similar to that in normal women. Aspirin does not affect fetal development and protects the mother against thromboembolism.
No mother or infant in this study had any clinical evidence of hemorrhage. A word of caution should be given about the use of aspirin near the delivery period. In a recent study on the effects of acetylsalicylic acid on maternal and neonatal hemostasis, it was shown that minor cutaneous bleeding episodes are very common in infants. Although serious hemorrhage was not observed in this study, intracranial hemorrhage has been described in premature infants. Because of the potential harmful effect of aspirin, women with bioprosthesis who are in sinus rhythm should not be treated with acetylsalicylic acid during pregnancy because the risk of thromboembolism in these patients is almost nil. Further data are not available on the risk-benefit balance of aspirin in pregnant women in atrial fibrillation. We would be inclined, however, to use platelet antiaggregants because the potential threat of thromboembolism in this type of patient seems more important than the potential harmful effect of aspirin.
In selection of prostheses for women who wish to have children, consideration should be given to the important deleterious effects that oral anticoagulants have upon the fetus and the mother during pregnancy. Tissue valves allow a normal pregnancy and delivery period independent of the atrial rhythm. The risk of thromboembolism can be controlled with platelet antiaggregants, and there is no need for antivitamin К derivatives. Although limited durability of bioprosthesis is a well-known fact, we believe that this group of patients should have their valves replaced with tissue valves even if they will be at risk of another operation in the future.