Determinantes da fraqueza e propriedades contráteis da musculatura inspiratória na insuficiência cardíaca

AUTOR(ES)

Paula Aver Bretanha Ribeiro

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

2012

RESUMO

The inspiratory muscle weakness may be present in 30-50% of outpatients with chronic heart failure, with implications for the quality of life and prognosis. However, it is unclear what clinical and behavioral characteristics that would be associated with this dysfunction. Moreover, as are unclear the molecular mechanisms leading to dysfunction of the diaphragm. Contractile parameters including contraction force maximum passive force and kinetics of cross-bridges can be altered in patients with HF, and may be associated with the IMF. This thesis investigated, firstly, the determinants of IMF in comparison to peripheral muscle weakness (handgrip) in patients with CHF. We evaluated clinical, anthropometric and behavioral disorders in these patients. The results showed that only about 50% of IMW can be explained by the variables. Furthermore, the variables associated with weakness of grip are not different from those found in healthy subjects (gender and age). However, maximum inspiratory force may be associated with markers of patient s functional capacity. Next, we investigated the contractile properties, assets and liabilities of myofibrils of cardiac muscle and diaphragm in an animal model of mice with heart failure developed by knockout arginilação cardiac-specific. Results show compatibility with the cardiac muscle contractile dysfunction found in human with congestive heart failure, such as reduction of maximum contraction, reduction and reduction of the passive force relaxation kinetics. However, the results of the diaphragm, we found increased maximum force of contraction, which may suggest a compensatory adaptive changes associated with increased inspiratory work associated with chronic heart failure. In conclusion, less than 50% of the variance in inspiratory muscle strength can be explained by behavioral and clinical variables of patients with chronic heart failure. In an animal model of heart failure that results in decreased contractility cardiomyofibrils, there was an increase in contractility of the diaphragm myofibrils, suggesting that inspiratory muscle weakness associated with chronic heart failure is not secondary to contractile dysfunction of the respiratory muscles.

ASSUNTO(S)

insuficiência cardíaca heart failure muscle weakness músculos respiratórios muscle biophysics biofísica

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