Disfunção endotelial no acidente vascular cerebral (AVC): relações com a lateralidade do AVC e o desempenho cardiorrespiratório durante o caminhar
Ribeiro, Jean Alex Matos
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Most individuals who have suffered a stroke have endothelial dysfunction, regardless of age, sex, stage of stroke (acute, subacute or chronic) and cardiovascular risk factors. Since the endothelium participates in the cardiovascular oxygen transport system by helping in the speed of energy production during the performance (mean response time of oxygen uptake on-kinetics, MRTON) and recovery of a physical activity (mean response time of oxygen uptake off-kinetics, MRTOFF), this endothelial dysfunction may be related to a worse cardiorespiratory performance in everyday tasks, such as walking, in post-stroke individuals, especially those with right hemisphere brain damage. There is evidence of a reciprocal influence between sympathetic activation and endothelial function, which helps to explain the direct relationship between sympathetic hyperactivity and endothelial dysfunction in some populations. Thus, the severity of endothelial dysfunction among post-stroke individuals may be related to the side of brain damage, since studies indicate greater sympathetic hyperactivity among those who have right hemisphere brain damage when compared with those who have left hemisphere brain damage. Therefore, this thesis includes new scientific evidence relevant for the field of Neurofunctional Physical Therapy, in which we sought to understand the relationships between endothelial dysfunction and laterality of brain damage and cardiorespiratory performance during walking among post-stroke individuals. Both studies were observational cross-sectional. Endothelial function was measured by flow-mediated dilation technique derived from the brachial artery (FMDBA) using ultrasound. Oxygen uptake during the xix-minute walk test (6MWT) was collected using a portable ergospirometer and a monoexponential adjustment was performed to obtain the MRTON and MRTOFF, being later corrected by the work rate during the 6MWT (wMRTON and wMRTOFF, respectively). For statistical analysis, Student’s t test (t) or Spearman’s correlation coefficient were used. The first study (Manuscript 1) aimed to examine whether endothelial dysfunction differs among post-stroke individuals according to the side of brain damage (right-sided stroke versus left-sided stroke). Thirty chronic post-stroke individuals were analyzed [right-sided stroke (n = 16; mean age = 58±8 years old; male = 81%); left-sided stroke (n =14; mean age = 62±9 years old; male = 50%)]. On average, individuals with right-sided stroke had lower FMDBA compared to those with left-sided stroke. This difference (FMDBA = 2.51%) was statistically significant (t = 2.185, p = 0.037), and it represented a medium effect size (r = 0.38). In conclusion, the findings of the first study indicate that individuals with right-sided stroke have greater endothelial dysfunction, making them more susceptible to cardiovascular events. The second study (Manuscript 2) aimed to examine whether endothelial dysfunction is related to cardiorespiratory performance (wMRTON and/or wMRTOFF) during walking. Twenty-two chronic post-stroke individuals were analyzed (mean age = 61±9 years old; male = 64%). No relationship was observed between FMDBA and cardiorespiratory performance during [wMRTON (rs = -0.23, p = 0.31)] and after the 6MWT [wMRTOFF (rs = -0.18, p = 0.43)]. Thus, we conclude that cardiorespiratory performance during walking is not related to endothelial dysfunction in chronic post-stroke individuals.
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