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P regnancy is associated with increased risk of thrombosis among women with mechanical prosthetic heart valves. 1 The largest literature review of women with a prosthetic heart valve who were on anticoagulation during pregnancy reported that thromboembolic complications occurred in 3.9% of women taking only warfarin, 9.2% of women who received unfractionated heparin in the first trimester followed by warfarin, and one fourth of women treated with unfractionated heparin throughout their pregnancy. Maternal death was observed in these groups in 2%, 4%, and 15%, respectively, and was usually related to prosthetic valve thrombosis (PVT).2 Similarly, 15% of pregnant women developed PVT while using low-molecular-weight heparin. The guidelines suggest optimizing anticoagulation in noncritically ill patients with recent subtherapeutic anticoagulation. Surgery is recommended when anticoagulation fails, for critically ill patients with obstructive thrombosis, or for patients with large (≥10 mm) nonobstructive PVT complicated by embolism. Fibrinolysis is recommended for either critically ill patients when Background-Prosthetic valve thrombosis during pregnancy is life-threatening for mother and fetus, and the treatment of this complication is unclear. Cardiac surgery in pregnancy is associated with very high maternal and fetal mortality and morbidity. Thrombolytic therapy has rarely been used in these patients. The aim of this study is to evaluate the safety and efficacy of low-dose (25 mg), slow infusion (6 hours) of tissue-type plasminogen activator for the treatment of prosthetic valve thrombosis in pregnant women. Methods and Results-Between 2004 and 2012, tissue-type plasminogen activator was administered to 24 consecutive women in 25 pregnancies with 28 prosthetic valve thrombosis episodes (obstructive, n=15; nonobstructive, n=13). Mean age of the patients was 29±6 years. Thrombolytic therapy sessions were performed under transesophageal echocardiography guidance. The mean dose of tissue-type plasminogen activator used was 48.7±29.5 mg (range, 25-100 mg). All episodes resulted in complete thrombus lysis after thrombolytic therapy. One patient had placental hemorrhage with preterm live birth at the 30th week, and 1 patient had minor bleeding. Conclusions-Low-dose, slow infusion of tissue-type plasminogen activator with repeated doses as needed is an effective therapy with an excellent thrombolytic success rate for the treatment of prosthetic valve thrombosis in pregnant women. This protocol also seems to be safer than cardiac surgery or any alternative medical strategies published to date. Thrombolytic therapy should be considered first-line therapy in pregnant patients with prosthetic valve thrombosis.

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Background-Distinguishing pannus and thrombus in patients with prosthetic valve dysfunction is essential for the selection of proper treatment. We have investigated the utility of 64-slice multidetector computed tomography (MDCT) in distinguishing between pannus and thrombus, the latter amenable to thrombolysis. Methods and Results-Sixty-two (23 men, mean age 44±14 years) patients with suspected mechanical prosthetic valve dysfunction assessed by transesophageal echocardiography were included in this prospective observational trial. Subsequently, MDCT was performed before any treatment was started. Periprosthetic masses were detected by MDCT in 46 patients, and their attenuation values were measured as Hounsfield Units (HU). Patients underwent thrombolysis unless contraindicated, and those with a contraindication or failed thrombolysis underwent surgery. A mass which was completely lysed or surgically detected as a clot was classified as thrombus, whereas a mass which was surgically detected as tissue overgrowth was classified as pannus. A definitive diagnosis could be achieved in 37 patients with 39 MDCT masses (22 thrombus and 17 pannus). The mean attenuation value of 22 thrombotic masses was significantly lower than that in 17 pannus (87±59 versus 322±122; P<0.001). Area under the receiver operating characteristic curve was 0.96 (95% confidence interval: 0.91-0.99; P<0.001), and a cutoff point of HU≥145 provided high sensitivity (87.5%) and specificity (95.5%) in discriminating pannus from thrombus. Complete lysis was more common for masses with HU<90 compared with those with HU 90 to 145 (100% versus 42.1%; P=0.007). Conclusions-Sixty-four slice MDCT is helpful in identifying masses amenable to thrombolysis in patients with prosthetic valve dysfunction. A high (HU≥145) attenuation suggests pannus overgrowth, whereas a lower value is associated with thrombus formation. A higher attenuation (HU>90) is associated with reduced lysis rates. (Circ Cardiovasc Imaging. 2015;8:e003246.