Função sistólica do ventrículo esquerdo em cães com doença mixomatosa valvar mitral
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2019-12-27
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Universidade Federal de Goiás
Resumo
Myxomatous mitral valve disease (MMVD), or mitral valve endocardiosis, is the most prevalent
acquired heart disease in dogs, being the main cause of heart failure in small dogs. The
echocardiographic examination, which allows cardiac morphological and functional evaluation,
is considered the “gold standard” test for diagnosing and staging MMVD in dogs. Information
obtained by echocardiography on ventricular function also determines the prognosis in dogs
with MMVD, since systolic dysfunction is a risk factor in these patients and contributes to the
development of heart failure. However, the assessment of ventricular systolic function using
conventional echocardiographic indexes is limited, since it is directly influenced by preload and
afterload factors. The evaluation of cardiac mechanics by strain (ST) and strain rate (STR),
using two-dimensional speckle tracking (2D-STE), allows, in humans, an earlier diagnosis of
ventricular dysfunction. In addition, the mitral ring tissue displacement (TMAD) is an index of
longitudinal systolic function that has a good correlation with conventional echocardiographic
indices and low intra and interobserver variability. Thus, the objective of this study was to
verify whether the myocardial deformity indexes (ST and STR) and the TMAD are more
accurate and precocious than the conventional echocardiographic indexes in the assessment
of left ventricular systolic function in dogs with MMVD, measuring the variables in the day of
diagnosis (T0) and after 30 days (T30). For this purpose, 29 dogs were evaluated, categorized
according to the ACVIM consensus, eight of which were in stage B1, 12 in stage B2 and nine
in stage C. Considering the conventional variables used in this study, the presence of systolic
dysfunction was not observed in dogs with MMVD, however changes after the start of
pharmacological treatment were observed in the variables FET% and MAM. From the 2D-STE
evaluation, similar to the conventional evaluation, systolic dysfunction cannot be determined
in dogs with MMVD. However, the longitudinal ST variable indexed by weight showed a
significant increase between the assessment times in group C, being still significantly higher
in C than in B2, at administration, and higher in C than in the other groups after treatment.
For the variable longitudinal STR it decreased in T30 in B1 and increased in C. When comparing
the groups, in T30, group C showed higher values than in B1 and B2. Still, the variables
longitudinal ST and TMAD showed a significant negative correlation when indexed to weight.
In conclusion, the assessment of myocardial deformity using 2D-STE assessment did not
demonstrate superiority compared to conventional indices for the diagnosis of systolic
dysfunction in dogs with MMVD in its different stages.
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SOUSA, P. R. Função sistólica do ventrículo esquerdo em cães com doença mixomatosa valvar mitral. 2019. 57 f. Dissertação (Mestrado em Ciência Animal) - Universidade Federal de Goiás, Goiânia, 2019.