Mechanical prosthetic valves
Pregnancy itself is a hypercoagulable state, and therefore the risk of thrombosis of a mechanical
valve during pregnancy is increased. The risk is greater with older generation mechanical prostheses in
the mitral position than in the aortic position. Anticoagulation is discussed in more detail later. In
patients who have a mechanical valve, serial echocardiography to document transvalvular gradients is
important, and thrombosis should be considered if acute symptoms develop along with echocardiographic
evidence of an increase in transvalvular gradient or reduced leaflet mobility. If valve thrombosis
is suspected, then fluoroscopic screening of the valve leaflets should be performed with
appropriate lead shielding. This can be performed with very low radiation doses, and the benefits of
clarifying the diagnosis outweigh the small radiation-related risks. Surgery is usually required
although successful thrombolysis even during pregnancy has been reported [32].