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You are here: Contents > 2016 > Volume 25 Number 1 January 2016 > REPLACEMENT DEVICE EVALUATION > Histopathological and Immunohistochemical Evaluation of Pannus Tissue in Patients with Prosthetic Valve Dysfunction

Histopathological and Immunohistochemical Evaluation of Pannus Tissue in Patients with Prosthetic Valve Dysfunction

Süleyman Karakoyun1,2, Mustafa Ozan Gürsoy2, Mahmut Yesin2, Macit Kalçık2, Mehmet Ali Astarcıoğlu2, Sabahattin Gündüz2, Ali Emrah Oğuz2, Şermin Çoban Kökten3, Ayşe Nimet Karadayı3, Altuğ Tuncer4, Cengiz Köksal4, Tayyar Gökdeniz1,2, Mehmet Özkan1,2

1Department of Cardiology, Kafkas University Medical School, Kars, 2Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, 3Department of Pathology, Dr. Lutfi Kırdar Kartal Training and Research Hospital, Istanbul, 4Department of Cardiovascular Surgery, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey

Background and aim of the study: Prosthetic valve dysfunction due to pannus formation is a rare but serious complication. Currently, limited data are available concerning the pathogenesis and immunohistochemical properties of pannus. The study aim was to investigate the morphological, histopathological and immunohistochemical characteristics of pannus formation in patients with prosthetic valve dysfunction.

Methods: A total of 35 patients (10 males, 25 females; mean age 44 ± 16 years) who had undergone re-do valve surgery due to prosthetic valve obstruction was enrolled in the study. Immunohistochemical studies were aimed at evaluating the expression of alphasmooth muscle actin (α-SMA) and desmin in myofibroblasts and smooth muscle cells; epithelial membrane antigen (EMA) in epithelial cells; and CD34, Factor VIII and vascular endothelial growth factor (VEGF) in endothelial cells. Matrix metalloproteinases (MMPs) -2 and -9, and transforming growth factor-beta (TGF-β) were used to demonstrate cytokine release from macrophages, leukocytes, fibroblasts and myofibroblasts.

Results: Pannus appeared as a tough and thick tissue hyperplasia which began from outside the suture ring in 

 

the periannular region and extended to the inflow and outflow surfaces of the prosthetic valves. Histopathological analysis showed the pannus tissue to consist of chronic inflammatory cells (lymphocytes, plasma cells, macrophages and foreign body giant cells), spindle cells such as myofibroblasts, capillary blood vessels and endothelial cells laying down the lumens. Calcification was present in the pannus tissue of 19 explanted prostheses. Immunohistochemical studies revealed positive α-SMA expression in all patients, whereas 60.5% of patients were positive for desmin, 50% for EMA, 42.1% for VEGF, 39.5% for TBF-β, 42.1% for MMP-2, 86.8% for CD34, and 97.4% for Factor VIII. MMP-9 was negative in all patients.

Conclusion: Pannus tissue appears to be formed as the result of a neointimal response in periannular regions of prosthetic valves that consist of periannular tissue migration, myofibroblast and extracellular matrix proliferation with vascular components. It is a chronic active process in which mediators such as TGF-β, VEGF and MMP-2 play roles in both matrix formation and degradation.

The Journal of Heart Valve Disease 2015;24:104-111


Histopathological and Immunohistochemical Evaluation of Pannus Tissue in Patients with Prosthetic Valve Dysfunction

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