Histologic findings in left ventricle papillary muscle arteries from human hearts

We describe original histologic findings of left ventricle papillary muscle (LVPM) arteries in people under 30 years of age. We examined 666 samples taken from the tip, mid-portion and base of papillary muscles in 56 males and 55 females, as well as several samples from the rest of the left ventricle. The number of smooth muscle cells (SMC) in the tunica media of the LVPM arteries led us to divide the samples examined into three groups: (i) group 1, 355 samples (53%) with a normal number of SMC and a normal lumen (the number of group 1 samples increased from the tip (21%) to the base (47%)); (ii) group 2, 252 samples (38%) with a mild to moderately increased number of SMC (the number of these samples decreased from the tip (44%) to the base (22%)); and (iii) group 3, 59 samples (9%) with abundant SMC that were more than twofold greater in size and number of normal arteries, in contrast with the other two groups. The shape of the SMC in group 3 samples was round and the extremely narrow, centrally located lumen of these SMCE had a round or oval shape. These changes were restricted only to papillary muscle arteries and the number of group 3 samples decreased from the tip (63%) to the mid-portion (37%). No inflammatory reaction or chronic ischemic changes were found in the LVPM arteries and surrounding area. The SMC changes in groups 2 and 3 were found in subjects aged more than 2 months. These findings will provide anatomists, cardiologists, pathologists and physiologists with valuable knowledge and will trigger further investigation into the etiology of the structural changes observed and their evolution with age.