Mechanical Valve Thrombosis in a Pregnant Patient: A Case of Therapeutic Failure

Mechanical valve thrombosis is life-threatening complication especially in pregnant patients. The optimal anticoagulation regimen is still not certain as there are different fetal and maternal risks associated with anticoagulation. A 37-year-old woman with a history of rheumatic heart disease with a mechanical mitral valve replacement 13 years prior presented to the hospital with dyspnea on mild exertion associated with orthopnea for three days. She was nine weeks pregnant, she had been on warfarin prior to pregnancy, and was switched to low molecular weight heparin (LMWH) in her 6th week of pregnancy. Fluoroscopy showed that one leaflet of the mitral valve was nearly fixed, while the other leaflet had restricted motion at maximal opening. Transesophageal echocardiogram (TEE) showed a very large thrombus approximately 3-4 cm² encompassing the entire mechanical valve with one immobile leaflet and limited mobility in other leaflet. In view of her clinical status (dyspnea with NYHA Class IV symptoms), the patient underwent uncomplicated bioprosthetic mitral valve replacement. However, the fetus did not survive. Mechanical heart valve (MHV) thrombosis is life-threatening complication in pregnancy. The optimal anticoagulation therapy in pregnancy is unclear. This case report brings into light that in spite of adequate anticoagulation, pregnant patients with mechanical heart valves are still at a high risk of developing valve thrombosis. It highlights the use of transthoracic and transesophageal echocardiogram along with fluoroscopy in diagnosing this and discusses the therapeutic options for this unique condition.