Histochemical and ultrastructural characteristics of leg muscle fibres in patients with repairative abdominal aortic aneurysm (AAA)

Tibialis anterior (ta) muscle biopsies before and after elective abdominal aortic aneurysm (AAA) repair operation were obtained, in order to observe p ossible changes after the aortic declamping reperfusion. Open muscle biopsi es were taken from each of eight patients (60-75 years old) which were proc essed for enzyme histochemistry, and for transmission electron microscopy ( EM). Morphometric analysis was applied to estimate the number and the area of muscle fibres of each fibre type. Rectus abdominis muscle biopsies were served as controls. Before the operation the predominant elements found wer e the presence of atrophic muscle fibres, fibre size diversity, localised c ellular reactions, increased extent of connective tissue, disappearance, in many cases, of the mosaic pattern, predominance of type I and oxidative fi bres, and existence of fibres with core-like structures in the sarcoplasm. Type I fibres consisted of 66.95 +/- 9% of all muscle fibres, the mean cros s sectional area of which was 3,372.8 +/- 1,016 mu m(2) and of type II fibr es was 3,786.5 +/- 6,046 mu m(2). After the aortic clamping was performed m itochondrial swelling was found, as well as disorganisation of sarcomeres. After declamping of the aorta, there were also severe edema, local fibre ne crosis, and adhesion of leucocytes, whereas muscle fibre areas became 3,935 .18 mu 531 mu m(2) for type I and 5,804 +/- 1,075 mu m(2) for type II. The short ischemic period during aortic clamping and the subsequent reperfusion resulted mainly in ultrastructural changes. Anat Rec 260:1-15, 2000. (C) 2 000 Wiley-Liss, Inc.