Fibrous tissue overgrowth and prosthetic valve endocarditis: report of a case.

Mechanical valve stenosis without restricted occluder motion and paravaluvular leakage developed in a patient who had undergone patch closure of partial atrioventricular septal defect and replacement of the left atrioventricular valve 13 years previously. Dense calcification of the supravalvular region was shown in a cineradiogram, whereas transthoracic and transesophageal echocardiography failed to reveal any obstructive mechanism. Elevated transprosthetic pressure gradient with unrestricted occluder motion suggested prosthetic valve stenosis resulting from fibrous tissue overgrowth, although this was not visualized by the modern diagnostic imaging tools. Reoperation confirmed calcified fibrous tissue overgrowth obstructing the mechanical valve inflow. Examination of resected tissue revealed prosthetic valve endocarditis due to alpha-streptococcus. Paravalvular leakage accompanying fibrous tissue overgrowth may indicate the presence of prosthetic valve infection even if the clinical manifestations are scarce.