Histopathological findings in skeletal muscle used in human dynamic cardiomyoplasty

Patients submitted to dynamic cardiomyoplasty had an initial clinical impro vement followed by a decrease in cardiac failure indices, A histopathologic al study of the skeletal muscle was undertaken to explain this. Latissimus dorsi fragments from 15 patients submitted to dynamic cardiomyoplasty in a 1:1 (heart beat:muscle stimulation) conditioning were analysed by light mic roscopy. The interval between surgery and obtaining the specimens (13 from necropsies, two from heart transplants) ranged from 37 days to 6 years. Nuc lear clumps and internalization, the presence of round fibres, inflammation , and fibrosis were analysed semi-quantitatively; the thickness of muscle f ibres and the percentage of tissue fat were measured by image analysis, The quantitative data were also compared, in 12 cases, with gender- and age-ma tched necropsy controls. The mean thickness of muscle fibres in cases and c ontrols was 27.21+/-5.33 and 40.84 +/- 9.42 mum, respectively (p = 0.001). The percentage of tissue fat in cases and controls was 12.04+/-12.66% and 0 .93+/-0.91%, respectively (p=0.008). The duration of grafts correlated posi tively with the quantity of nuclear clumps (R=0.80, p<0.001) and round fibr es (R=0.53, p = 0.04), as well as with the percentage of tissue fat (R = 0. 68, p = 0.005), Accordingly, a negative correlation was found between the d uration of grafts and the mean diameter of fibres, characterizing muscle at rophy (R = -0.66, p =0.01), The longer the post-surgical period, the more i ntense the degenerative lesions. This study shows that skeletal muscle used in human dynamic cardiomyoplasty may atrophy and be replaced by fat when s timulation is synchronized to every cardiac beat. These findings could pla) a role in explaining the long-term results of this surgical procedure. Cop yright (C) 2001 John Wiley & Sons, Ltd.