A 69-year-old woman with a mechanical aortic valve presented with decompensated heart failure. Emergent echocardiogram and fluoroscopy demonstrated acute aortic regurgitation due to a dysfunctional mechanical aortic valve and non-obstructive coronary disease. An emergent valve replacement was performed confirming a fixed-open valve with pathology demonstrating obstructive pannus formation without thrombosis or vegetation.

This meta-analysis investigated the diagnostic values of transthoracic echocardiography (TTE), 2-dimensional (2D) and 3-dimensional (3D) transesophageal echocardiography (TEE), and multidetector-row computed tomography (MDCT) in patients with suspected mechanical prosthetic valve obstruction (PVO) for detecting subprosthetic mass and differentiating its causes.
Diagnostic values of advanced imaging modalities, such as MDCT and TEE, for the detection and differentiation of PVO have not been investigated.
PubMed and EMBASE were systematically searched for studies that evaluated PVO using imaging modalities. The modified Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate study quality. Pooled sensitivity of each modality for PVO detection and pooled diagnostic accuracy of TEE and MDCT for differentiating the causes of PVO were analyzed. Study heterogeneity was also assessed.
Seventeen studies (229 patients) that used at least 1 index tool among TTE, TEE, or MDCT were included. For detecting a subprosthetic mass that caused PVO, 3D TEE and MDCT showed a higher sensitivity of 81% (95% confidence interval [CI]: 40% to 95%) and 88% (95% CI: 81% to 93%), respectively, compared with TTE (20%; 95% CI: 7% to 47%) and 2D TEE (68%; 95% CI: 46% to 84%). Pooled sensitivity and specificity for diagnosing thrombus as a cause of PVO was 75% (95% CI: 54% to 88%) and 75% (95% CI: 40% to 93%), respectively, for TEE and 45% (95% CI: 16% to 77%) and 90% (95% CI: 77% to 96%), respectively, for MDCT. Pooled sensitivity for diagnosing pannus as a cause of PVO was 62% (95% CI: 46% to 76%) for TEE and 85% (95% CI: 70% to 93%) for MDCT.
This meta-analysis suggested that MDCT and 3D TEE have higher sensitivity than do TTE and 2D TEE, and can be reliable imaging modalities for detecting a subprosthetic mass that causes PVO. Moreover, MDCT can more accurately differentiate the cause of PVO than does TEE.

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BACKGROUND: The clinical significance of pannus in the prosthetic mitral valve (MV) is not well documented.
OBJECTIVE: To investigate the clinical significance of pannus on cardiac computed tomography (CT) in patients with a prosthetic MV.
METHODS: A total of 130 patients with previous MV replacement who underwent cardiac CT were retrospectively included in this study. The presence of pannus, paravalvular leak (PVL) around the prosthetic MV and limitation of motion (LOM) of the MV were analyzed using CT. Between patients with MV pannus and those without pannus, CT, echocardiographic, and redo-surgery findings were compared. The diagnostic performance of CT and transesophageal echocardiography (TEE) for the detection of MV pannus was also compared, using surgical findings as a standard reference.
RESULTS: MV pannus was observed on cardiac CT in 32.3% of the study population. Patients with MV pannus detected on CT more commonly had LOM (28.2% vs. 15.2%) and less frequently had PVL of the prosthetic MV (16.7% vs. 25%) than patients without MV pannus (P>0.05). Prosthetic valve obstruction (PVO) due prosthetic MV pannus requiring redo-surgery was present in only five patients (11.9%). Cardiac CT detected MV pannus with sensitivity of 65.2% and specificity of 80.9% and showed better diagnostic performance than TEE (P<0.05).
CONCLUSIONS: Prosthetic MV pannus can frequently be seen on cardiac CT. However, its clinical significance should be assessed with careful consideration, because PVO due to MV pannus is relatively uncommon, and pannus can be seen in patients without any clinical problems.

Prosthetic valve obstruction (PVO) is a rare but feared complication of mechanical valve replacement. Diagnostic evaluation should focus on differentiating prosthetic valve thrombosis (PVT) from pannus formation, as their treatment options differ. History of sub-optimal anti-coagulation and post-op time course to development of PVO are useful clinical characteristics in differentiating thrombus from pannus formation. Treatment of PVT is influenced by the patient\'s symptoms, valve location, degree of obstruction and thrombus size and may include thrombolysis or surgical intervention. Alternatively, pannus formation requires surgical intervention. The purpose of this article is to review the pathophysiology, epidemiology, diagnostic approach and treatment options for aortic and mitral valve PVO.

BACKGROUND: Rheumatic heart disease is the most common cardiac disease in Yemen. It is associated with high morbidity and mortality. Valve replacement is the most common open heart surgery procedure in our cardiac center. The use of mechanical valves remains burdened with serious complications such as thrombosis. Valve thrombosis is still associated with high mortality(]) The reported mortality rate of the redo operation ranges from 8 to 20% and up to 37-54% in critically ill patients.
OBJECTIVE: The aim of the present study was to investigate mechanical valve obstruction among Yemeni patients.
METHODS: Between January 2003 and April 2007, 2794 patients underwent prosthetic valve replacement in our center, Al-Thawra Hospital. Of those patients, 129 (4.6%) underwent reoperation for te obstructive mechanical valve. Patients with clinical suspicion of prosthetic valve obstruction (PVO) were admitted emergently to the CCU and the diagnosis was confirmed with echocardiography. All patients had heart failure; 95% of them were in NYHA class IV. All were transferred directly from the CCU to the operating room. The mean age was 34.8 ± 13.4 years. Two patients received preoperative thrombolytic therapy that was not successful. Obstruction involved the mitral valve prosthesis in 47 (36.4%); the aortic prosthesis in 16 (12.4%) patients; both valves in 21 (16.3%) patients; mitral valve replacement with tricuspid valve repair in 22(17%); double valve replacement with tricuspid valve repair in 1 (0.8%); redo mitral valve replacement with aortic valve cleaning in 7 (5.4%) cases; aortic valve cleaning in 5 (3.9%) patients; mitral valve cleaning in 5 (3.9%); and 5 (3.9%) patients had redo mitral with aortic replacement.
RESULTS: The operations were performed urgently. The etiology of the obstruction was thrombus in 111 (86%), pannus formation in 4 (3%), pannus and thrombus in 6 (4.8%), vegetation in 7 (5.4%) patients, and interposition of suturing materials in 1 (0.8%) patient. The in- hospital mortality was 23/129 (17.8%).
CONCLUSIONS: The incidence of prosthetic valve obstruction remains high in Yemen. The vast majority of the patients who are referred to our hospital come from remote provinces in the country where regular INR measurement is not readily available. For those who are living in areas without good medical care, certain measures are necessary to avoid this disastrous complication: (1) good patient education, (2) free INR testing and free anticoagulant drugs such as warfarin; and (3) use of tissue rather than mechanical valves.