We describe histologically cases of patients between 31 and 60 years of age who had fibromuscular dysplasia (FMD) in the tunica media (TM) of the left ventricle papillary muscles (PM) arteries. We also compared them with our previous findings in subjects younger than 30 years of age. We examined histologically samples taken from the tip of the anterior PM of the left ventricle in 200 healthy male hearts. In 33 cases (16.5 %), FMD was in the TM. We divided these cases into three subgroups (A, B, C) based on the degree of replacement of smooth muscle cells by fibrous tissue, and thus identified 17, 11 and 5 cases, respectively. Until the age of 41, the typical lesions were often localized within the TM. Beyond that age, the fibrous tissue increased in the TM wall and in the surrounding area of the vessels, causing dysfunction of the PM. Degenerative lesions, as well as inflammatory infiltration, were found after the age of 53. The findings of this study will be useful to cardiologists and cardiac surgeons, in pointing out that, after the age of 44 years old, some PM and their supporting valves may present a degree of dysfunction.
Keywords: Fibromuscular dysplasia; Papillary muscle; Papillary muscle arteries; Tunica media.