Investigation of a Mechanical Valve Impairment after Eight Years of Implantation

A 55-year-old female who undergone mitral valve replacement eight years ago with a mechanical graft, presented accusing sudden decrease of effort tolerance and two episodes of pulmonary edema in the last month. Anamnesis, physical examination, electrocardiogram (ECG), transthoracic echocardiography and coronarography were performed. The mechanical valve leaflets and the tissue surrounding the prosthetic ring were evaluated by: optical microscopy (hematoxylin eosin stain and immunohistochemistry), scanning electron microscopy (SEM) and EDAX analysis (Energy Dispersive X-ray spectroscopy). Anamnesis: inferior myocardial infarction in 2006, congestive cardiac insufficiency, pulmonary hypertension, and arterial hypertension. Clinical examination and ECG: minimal perimaleolar edema bilateral, sinus rhythm on admission. Transthoracic echocardiography: 55% ejection fraction, a pression gradient across the mitral valve (Gmax/Gmed= 24/11 mmHg), tricuspid regurgitation, and pulmonary hypertension. A mitral prosthetic valve’s leaflet was found immobile. No thrombus was evidenced. Coronarography: an immobile graft’s leaflet, stenoses on the right coronary artery, stenosis on left anterior descending artery and occlusion at the circumflex artery emergence. The prosthesis was replaced, and two coronary artery bypasses were performed. Macroscopic examination: a fibroconjunctive tissue expansion in close contact with the leaflet. Histopathological evaluation: muscle cells with altered phenotypes, fibroblasts along with fibrous connective tissue and calcium depots areas. SEM evaluation: tissue depots on the immobile leaflet, suggesting that the connective tissue expansion was blocking the leaflet’s movements. EDAX analysis: the metallic leaflets surface was made of tantalum; sodium, calcium and chloride deposits were also detected. Graft failure was caused by the tissue proliferation affecting leaflet’s mobility. SEM is a viable method for failed cardiovascular grafts investigation.