P1.2 NANOMECHANICAL ALTERATIONS IN THE ADVENTITIAL LAYER OF THE INTERNAL MAMMARY ARTERY OF PATIENTS WITH HIGH PWV

Abstract

Aim: Arterial stiffening occurs as part of the natural ageing process, and is thought to be related to the accumulation of collagen and degradation of elastin. However, little is known about how regional variations in arterial structure and mechanical properties contribute to arterial stiffening. This study compared localised differences in the nano-structure and mechanical properties in the internal mammary arteries (IMA) from patients with high and low PWV. Methods: 6 IMAs were collected from coronary bypass operations and the patients were grouped according to their carotid-femoral PWV; high (14.6 ± 1.4 m/s) and low (8.7 ± 0.5 m/s). The nano-topography and elastic modulus were determined by atomic force microscopy (AFM) using 5 μm cryosections. Data are presented as means ± SEMs. Results: Overall, IMAs in the high PWV group were significantly stiffer than in the low PWV group (High; 2234.7 ± 72.3 MPa, Low; 2015.3 ± 58.4 MPa), (p < 0.0001). Although no significant difference was found in the intimal or medial layers, the adventitia was stiffer in the high PWV group (High; 2597.6 ± 135.7 MPa, Low;2215.6 ± 110.2 MPa), (p < 0.001). Furthermore, the collagen fibrils in the adventitia of the high PWV group were found to have a smaller diameter (High; 118.44 ± 1.1 nm, Low; 123.81 ± 1.3 nm), (p < 0.01)). Conclusion: Overall, the nanomechanical data associates with PWV data. The high PWV group exhibited higher nanomechanical stiffness alongside morphological alterations within the adventitial layer.