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

Abstract

Tibialis anterior (ta) muscle biopsies before and after elective abdominal aortic aneurysm (AAA) repair operation were obtained, in order to observe possible changes after the aortic declamping reperfusion. Open muscle biopsies were taken from each of eight patients (60-75 years old) which were processed 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 were the presence of atrophic muscle fibres, fibre size diversity, localised cellular reactions, increased extent of connective tissue, disappearance, in many cases, of the mosaic pattern, predominance of type I and oxidative fibres, 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 cross sectional area of which was 3,372.8 +/- 1,016 microm(2) and of type II fibres was 3,786.5 +/- 6,046 microm(2). After the aortic clamping was performed mitochondrial swelling was found, as well as disorganisation of sarcomeres. After declamping of the aorta, there were also severe edema, local fibre necrosis, and adhesion of leucocytes, whereas muscle fibre areas became 3,935.18 micro 531 microm(2) for type I and 5,804 +/- 1,075 microm(2) for type II. The short ischemic period during aortic clamping and the subsequent reperfusion resulted mainly in ultrastructural changes.