RESUMO
INTRODUCTION: Stimulation of the phrenic nerve via cervical magnetic stimulation (CMS) elicits a compound muscle action potential (CMAP) that allows for assessment of diaphragm activation. The reliability of CMS to evoke the CMAP recorded by chest wall surface EMG has yet to be comprehensively examined. METHODS: CMS was performed on healthy young males (n=10) and females (n=10). Surface EMG electrodes were placed on the right and left hemi-diaphragm between the 6-8th intercostal spaces. CMAPs were analysed for: latency, duration, peak-to-peak amplitude, and area. Reliability within and between experimental sessions was assessed using intraclass correlation coefficients (ICC). Bilateral (right-left) and sex-based (male-female) comparisons were also made (independent samples t-test). RESULTS: All CMAP characteristics demonstrated high reproducibility within (ICCs>0.96) and between (ICCs>0.89) experimental sessions. No statistically significant bilateral or sex-based differences were found (p>0.05). DISCUSSION: CMS is a reliable and non-invasive method to evaluate phrenic nerve conduction.
Assuntos
Diafragma/fisiologia , Eletromiografia , Potencial Evocado Motor/fisiologia , Magnetismo/métodos , Parede Torácica/citologia , Parede Torácica/fisiologia , Adulto , Análise de Variância , Biofísica , Estimulação Elétrica , Feminino , Lateralidade Funcional , Humanos , Masculino , Condução Nervosa/fisiologia , Tempo de Reação/fisiologia , Reprodutibilidade dos Testes , Caracteres Sexuais , Adulto JovemRESUMO
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Assuntos
Feminino , Humanos , Dermatofibrossarcoma/induzido quimicamente , Dermatofibrossarcoma/patologia , Parede Torácica/anormalidades , Parede Torácica/lesões , Neoplasias/induzido quimicamente , Neoplasias/complicações , Tronco/anormalidades , Tronco/crescimento & desenvolvimento , Dermatofibrossarcoma/metabolismo , Dermatofibrossarcoma/mortalidade , Parede Torácica/citologia , Parede Torácica/metabolismo , Neoplasias/metabolismo , Neoplasias/fisiopatologia , Tronco/patologia , Tronco/cirurgiaRESUMO
The left atrial posterior wall (LAPW) plays a critical role in atrial fibrillation, but the underlying mechanism remains unclear. In the present study, we sought to characterize the histological features of the LAPW. Different atrial regions were dissected from hearts of normal Sprague-Dawley rats and humans. Haematoxylin/eosin and van Gieson staining were used to analyse atrial cardiomyocyte arrangement and collagen distribution, respectively. Intercellular junctions were evaluated by transmission electron microscopy. In contrast with other atrial regions, the LAPW exhibited more disorganized cardiomyocytes, larger intercellular spaces and variable myocardial fibre arrangement. The proportion of collagen was significantly higher in the LAPW than in other atrial regions. Interestingly, desmosomes were sparse along with intercellular gaps in the LAPW. In summary, distinct disarrangement of cardiomyocytes and an abundance of collagen exist in the LAPW. The sparsity of desmosomes in the LAPW may be related to the heterogeneous distribution and separation of atrial myocytes.
