Prosthetic Mitral Valve Obstruction: Pannus, Thrombus or Both?

Abstract

Background: Prosthetic mitral valve obstruction is an uncommon but serious complication after mechanical valve replacement. It is usually caused by pannus, thrombus, or both together. Distinguishing between these causes is essential because the treatment and prognosis differ, yet diagnosis can be difficult since imaging findings often overlap and surgical confirmation is sometimes needed. Case Presentation: A 42-year-old woman with a previous mechanical mitral valve replacement presented with increasing shortness of breath and orthopnea. On examination, the prosthetic click was faint, and signs of pulmonary congestion were present. Echocardiography showed high transvalvular gradients and limited leaflet motion. Cine-fluoroscopy confirmed restricted movement of one leaflet, while cardiac CT identified a dense structure around the sewing ring suggesting pannus with a superimposed low-density thrombus. Laboratory results were normal, including coagulation tests. Despite optimized anticoagulation, the patient’s condition worsened, and urgent reoperation was performed. Surgery confirmed mixed pannus and thrombus formation obstructing the prosthesis. The valve was replaced, and recovery was uneventful. Discussion: This case highlights the difficulty of distinguishing pannus from thrombus in prosthetic mitral valve obstruction and shows the importance of combining different imaging techniques. Recognizing this dual mechanism early can help guide appropriate management and improve patient outcomes.