A rare cause of dysfunction of mechanical aortic valve prosthesis in a young adult

A mechanical prosthetic valve dysfunction carries a high risk of hospitalization and patient death. It may show up as stenosis of the valve prosthesis or intra/paraprosthetic regurgitation. Prosthetic stenosis, in turn, may be caused by granulation tissue (pannus), thrombosis, a combination of pannus and thrombosis, a prosthesis mechanical defect, or a unique surgical technique. Establishing the specific cause of prosthetic stenosis is of crucial importance for the therapeutic behavior. Prosthetic thrombosis requires conservative intensification of anticoagulation/fibrinolysis or surgical treatment in an accelerated/emergency manner. When the cause of the thrombosis is pannus, a mechanical defect, or surgical technique, the only treatment option is cardiac surgical reintervention. The manifestation of granulation tissue (pannus) is indicative of a non-immune reaction to the prosthetic valve and suture material following prosthetic valve replacement. The basis of this phenomenon is the growth of fibroelastic tissue associated with an increase in the expression of transforming growth factor beta. [1] In a small proportion of patients with implanted prosthetic valves, the growth of pannus leads to subvalvular obstruction of blood flow and results in prosthetic stenosis. Despite the technological advancements in imaging diagnostics, visualizing pannus remains challenging and not always feasible. Consequently, we employ a multifaceted approach that incorporates anamnestic, clinical, and imaging methods to reach a diagnosis. Operative exploration is the only method by which definitive confirmation can be obtained. The objective of this article was twofold: first, to present a rare case of stenosis of a mechanical aortic valve prosthesis due to a circumferential shaft of granulation tissue (pannus) forming a kind of de novo subaortic membrane; and second, to outline an algorithm for the diagnosis of prosthetic valve stenosis and differential diagnosis between thrombosis and pannus as the cause of valve dysfunction. The following case study presents a patient who met the surgical treatment indications due to stenosis of a mechanical aortic valve prosthesis. The clinical information and imaging studies indicated that the prosthetic dysfunction was likely due to the presence of granulation tissue (pannus). The intraoperative finding revealed a circumferential shaft of granulation tissue, forming a novel subaortic membrane.