[Late thromboses on tricuspid valve prostheses. Apropos of 6 cases].

Six out of 24 patients with tricuspid valve prostheses, operated between 1968 and 1978, followed-up from 1 to 10 years (average 4,2 years) developed thrombosis. This complication occurred between 15 and 59 months after operation (average 37 months). All patients were female with ages ranging from 18 to 44 years (average 38 years). Starr-Edwards prostheses were used in all cases. Five of these patients were on anticoagulants therapy, which was well within therapeutic limits in 3 patients. In contrast to thrombosis of mitral or aortic valve prostheses, the presenting symptoms were slowly progressive and discreet in 4 patients; in 1 case, the thrombosis was diagnosed on routine follow-up examination. The slow clinical presentation allows time for useful complementary investigations, catheterisation and angiocardiography being the most reliable methods of confirming this difficult diagnosis: these investigations were carried out in 2 patients, and in both cases, very high right atrial pressure with diastolic gradients between the right atrium and right ventricle of over 10 mm Hg were recorded. Cineangiography showed tricuspid regurgitation in both cases with reflux in the vena cavae and very dilated right atria, stagnation of contrast and poor right ventricular filling. Five patients were reoperated with two postoperative deaths. Particular anatomical appearances were observed at operation or autopsy with fibrin and platelet deposits at different levels of the prosthesis (sewing ring and/or struts) interfering and even blocking the function of the ball or disc. Organized thrombus on the cage was only observed in one patient. In this case, the struts on the prosthesis were set in the right ventricular cavity. Thrombosis of tricuspid valve prostheses is generally a slowly progressive complication and may be diagnosed in time by regular follow-up, so that reoperation may be considered without unnecessary delay.