A 29-year-old woman with two mechanical valve prostheses was referred to our institution for sudden and self-resolved diplopia 2 weeks after childbirth. From the beginning of pregnancy, nadroparin was started instead of warfarin. The echocardiogram performed at hospital admission revealed a severe aortic prosthesis regurgitation due to incomplete leaflet apposition with a prosthetic aortic transvalvular gradient increase. Three-dimensional transoesophageal echocardiography revealed a thrombus located between the two prostheses, causing intermittent aortic valve malfunction. Intravenous heparin was started. Three days later, a second transoesophageal echocardiogram revealed a decreased aortic transvalvular gradient, but an oval thrombus adhered to the mitral prosthesis and fluctuating through the prosthetic valve was detected. Tissue plasminogen activator infusion was started. To reduce cerebral embolization, carotid filters used during artery angioplasty were placed in common carotid arteries, left and right. No complication occurred during and after the procedure. With thrombus absence at 30-min transoesophageal echocardiography, filters were removed. The patient continued intravenous heparin until achievement of a therapeutic international normalized ratio range and she was asymptomatic on discharge.