Histomorphometric and sympathetic innervation of the human posterior intercostal artery and its clinical importance

The purpose of this investigation was to study the characteristics of arterial wall and sympathetic innervation of the human posterior intercostal artery (PIA) in order to assess its suitability as an arterial graft for vascular surgeries. Fifty PIA samples were obtained from 25 cadavers (18 males and 7 females). Samples were divided into three age groups: group 1: 19-40years; group 2: 41-60years; and group 3 over 61 years. Sections (5 μm-thickness) of each sample were taken and stained with haematoxylin-eosin, Verhoeff's-Van Gieson. Five samples were processed for tyrosine hydroxylase immunostaining. The differences in the thickness of tunica intima were not statistically significant when group 1 was compared with group 2(p = 0.798), but significant differences were observed in the thickness of the tunica intima when comparing group 2 with group 3 (p = 0.012) and group 3 with group 1 (p = 0.002). The tunica media was not statistically significant when group 1 was compared with group 2(p = 0.479). However, significant differences were observed in the thickness of the tunica media when comparing group 2 with group 3 (p = 0.001) and group 3 with group 1 (p = 0.011). The mean (SD) number of elastic laminae in group 1, group 2, and group 3 were 7.88 ± 0.69, 6.62 ±0.51, and 4.56 ± 0.82, respectively. Tunica intima/media ratios in groups 1, 2, and 3 were found to be 0.09 ± 0.01, 0.11 ± 0.02, and 0.27 ±0.16, respectively. Tyrosine hydroxylase immunostaining revealed that sympathetic fibres are found mainly in the tunica adventitia and at the adventitia-medial border. The sympathetic nerve fibre area and sympathetic index were found to be 0.004 mm ², and 0.151 mm ², respectively. PIA has relatively thin intima and media, which are favourable features regarding its potential suitability as an alternate coronary bypass conduit. (Folia Morphol 2011; 70, 3: 161-167)