What risks are associated with cardiac valve prostheses during pregnancy?

Women with prosthetic valves can tolerate the hemodynamic effects of pregnancy without long-term deleterious effects. Maternal risks are increased due to thromboembolic events or hemorrhagic complications from anticoagulation. Prophylaxis against valve thrombosis must be maintained throughout pregnancy, usually with adjusted-dose heparin to keep the activated partial thromboplastin time at 1.5-2.0 times normal at mid-interval between doses. Some data exist to support warfarin use from the second trimester until 36 weeks’ gestation, but this is controversial, to say the least.

Some suggest using bioprosthetic valves in young women of child-bearing age, because anticoagulation is often unnecessary with tissue valves. However, these valves are associated with a high failure rate, especially in women who become pregnant, and require replacement significantly more often than mechanical valves. Cryopreserved homografts are an emergency option.

Infective endocarditis is rare during pregnancy and delivery, but the consequences of prosthetic valve endocarditis are often catastrophic, so these women should be candidates for antibiotic prophylaxis during labor and delivery.

What other cardiac lesions necessitate endocarditis prophylaxis during delivery?

To be at risk for infective endocarditis, patients must not only have a condition but also undergo a procedure that places them at risk. Cesarean section, uncomplicated vaginal delivery, and therapeutic abortion are procedures not associated with endocarditis risk. There are, therefore, no cardiac conditions for which endocarditis prophylaxis is absolutely indicated during delivery.

How should a woman with congenital heart disease be counseled during pregnancy?

Most women with congenital heart lesions have no genetic syndrome associated with the lesion. Assuming that teratogenic exposure is not the cause, the overall risk of recurrence in their children appears to be about 5%. Of note, children of affected mothers appear to have a higher risk than those of affected fathers. The explanation for this is not clear.

Many anatomic defects can be diagnosed prenatally, and the use of fetal echocardiography is recommended in all pregnant women with congenital heart disease.

1Can a woman breast-feed while taking a cardiac medication?

In almost all cases, breast-feeding women should be encouraged to continue. Only an estimated 2% of the maternal dose of a drug is ingested by the baby and is rarely of clinical significance. If necessary, drug levels can be monitored in breastfeeding infants.

Heparin does not get into breast milk, and the amount of warfarin ingested by the baby is too small to affect coagulation. Therefore, women taking warfarin may breast-feed their babies without concern.

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