Is Injury to the Thoracodorsal Nerve Present after Long Term Dy- namic Cardiomyoplasty in Goats?

Long term dynamic cardiomyoplasty is associated with atrophy, fibrosis, and fatty infiltration of the latissimus dorsi muscle (LDM). Ischemia, decreased muscle preload and chronic electrical stimulation have been recognized as factors for muscle deterioration after cardiomyoplasty. Transposition of the LDM around the heart might be associated with damages to the thoracodorsal nerve that can contribute to LDM deterioration. The purpose of the study was to evaluate the neuromuscular function of the thoracodorsal nerve and LDM after dynamic cardiomyoplasty. We performed neuromuscular functional analysis and histology on the LDM and thoracodorsal nerve of 6 normal goats and 6 goats after 6 months of dynamic cardiomyoplasty. Electromyographic analysis showed positive sharp waves and fibrillation potentials in the LDM of 3 goats from the dynamic cardiomyoplasty group. Conduction velocity of the thoracodorsal nerve of goats from the dynamic cardiomyoplasty group (58.32±9.80m/s) was reduced compared to the goats from the control group (71.48±5.71m/s, p=0.02). Loss of myelin sheaths, collapse of endoneurial connective tissue, and solitary foci of axonophagia and myelinophagia further documented severe injury to the thoracodorsal nerve in goats from the dynamic cardiomyoplasty group. The LDM wrap was denervated after long term dynamic cardiomyoplasty.