Is the use of low molecular weight heparin a rational choice during pregnancy in patients with a mechanical heart valve: a report of three cases.

Pregnancy is associated with an increased risk of valve thrombosis in patients with a mechanical prosthetic heart valve. The administration of low molecular weight heparin (LMWH) with regular anti-factor Xa assessment is a recommended treatment modality for these patients. Presently described are 3 cases of therapy with LMWH during pregnancy. Despite frequent anti-factor Xa monitoring, not surprisingly, all of them developed prosthetic valve thrombosis.