[Mechanic valve prosthesis and pregnancy: Is Phenprocoumon replaceable?]

We report the case of a 30-year-old pregnant patient with mechanical valve replacement in mitral and aortic position. She had discontinued Phenprocoumon-treatment in the 5+4 week of pregnancy by herself. Because of rheumatic fever she had undergone a mechanical aortic and mitral valve replacement 12 years ago. Due to a thrombosis of the mitral valve, an acute reoperation had to be done 5 years later. 2 years ago, a partially re-thrombosis of the mechanical mitral valve was treated by intravenous thrombolysis. These complications had been probably due to incomplicance. The patient had experienced 3 abortions before.

The vaginal sonography determined an intact gestation. The laboratory test revealed an INR of 1.2. The transesophageal echocardiography showed a partially thrombosed mechanical mitral valve. The abdominal ultrasonography detected an embolic splenic infarction.

These findings were consistent with partially thrombosed mechanical mitral valve with thromboembolic splenic infarction among incompetent oral anticoagulation. After initial heparinization with under twice daily control of the partial thromboplastin time the joint decision was made to restart Phenprocoumon (target INR 2.5 to 3.5, and additional ASS 100 mg /day). 9 days later the patient had a missed abortion. An uncomplicated curettage was performed under therapeutic i.v. heparinization.

The use of coumarins in pregnancy carries a fetal risk. But it is the most secure anticoagulation after a mechanical valve replacement, especially in high-risk patients. Alternatives are heparins. They don't cross the placenta but are associated with a slightly elevated risk of thromboembolism.