Teste de estresse com Dobutamina em cães com Doença Degenerativa Valvar Mitral
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Data
2018-04-12
Autores
Rodrigues, Bruno Cristian
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A degeneração mixomatosa da válvula mitral (DMVM) é a enfermidade mais comum na clínica de pequenos animais no âmbito das cardiopatias, cuja evolução pode resultar em alterações hemodinâmicas importantes decorrentes dos mecanismos neuro-hormonais compensatórios. Embora seu diagnóstico seja relativamente simples, as alterações intrínsecas podem ser subestimadas pelos exames convencionais, a exemplo da disfunção sistólica e reserva miocárdica que podem passar despercebidas à ecocardiografia. Desta forma, o objetivo do presente estudo foi avaliar a ocorrência de disfunção sistólica em cães com DMVM por meio do teste de estresse farmacológico com dobutamina. Para tanto, foram utilizados três grupos de cães: G1 (n=8) grupo controle, G2 (n=7) animais com DMVM e diâmetro interno do ventrículo esquerdo em diástole indexado à aorta (DIVEd/Ao) < 2,37 e G3 (n=6) animais com DMVM e DIVEd/Ao ≥ 2,37 em um total de 21 animais. O ecocardiograma foi realizado antes (T0) e após (T1) infusão contínua com dobutamina, que foi realizada da seguinte forma: 5μg/kg/minuto por cinco minutos e 10μg/kg/minuto durante 10 minutos (T1). Os resultados foram avaliados pelo teste de Tukey com nível de significância de 5% quanto às variáveis fração de ejeção (FEJ%) (variação percentual média (VPM) de FEJ% antes e após a infusão de dobutamina), VPM de fração de encurtamento (FEC%) e diâmetros internos do ventrículo esquerdo em sístole e diástole indexados pelo diâmetro da aorta (DIVEs/Ao e DIVEd/Ao). Os resultados acerca da VPM FEC% e VPM FEJ%,demonstraram que houve diferença estatística quanto à primeira variável entre os grupos G1 com G3, bem como entre G2 e G3, enquanto em relação à segunda, apenas o G1 e G3 diferiram estatisticamente. Por outro lado não houve diferença significativa (p>0,05) para as médias obtidas pré e pós dobutamina da FEC% e FEJ% entre todos os grupos, no entanto, houve diferença significativa dentro os grupos G1 e G2 quando analisados os momentos T0 e T1. Outrossim, verificando as médias obtidas do DIVEd/Ao, conclui-se que houve diferença entre os grupos G1 e G3 como também entre G2 e G3 (p<0,05). Por sua vez, as médias obtidas do DIVEs/Ao diferiram significativamente (p<0,05) em todos os grupos pré (T0) e pós dobutamina (T1), exceto no G3. Entre os grupos, as médias no T0, têm diferença estatística significante entre os grupos G1 e G3 (p<0,05). Ademais, Em relação ao VVEs/m², dentro dos grupos houve diferença significativa apenas entre G1 e G3. Já entre os tempos, apenas o G1 houve diferença entre T0 e T1. Por fim, constatou-se significância estatística (p<0,05) quando se correlacionou DIVEd/Ao com a VPM FEC% e VPM FEJ%, demonstrando que quanto maior o DIVEd/Ao menores são estas variáveis. Desta forma, conclui-se que a dobutamina é capaz de evidenciar disfunção sistólica em animais com DMVM, principalmente naqueles que têm um remodelamento maior (G3), sendo capaz de inferir uma forte relação entre o tamanho do DIVEd/Ao e disfunção sistólica. Além disso, notou -se que em animais com menor remodelamento do ventrículo esquerdo (VE), como os do grupo G2, a resposta inotrópica ao desafio farmacológico foi satisfatória, revelando a presença de reserva contrátil nestes pacientes. Por fim, o teste de estresse com dobutamina mostrou-se eficaz, seguro e aplicável na rotina clínica.
Myxomatous mitral valve disease (MMVD) is the most common cardiopathy in small animals, which evolution may result in important hemodynamic changes due to compensatory neurohormonal mechanisms. Although its diagnosis is relatively simple, intrinsic changes may be underestimated by conventional exams, as systolic dysfunction and myocardial reserve that may go unnoticed by echocardiograph. Therefore, the objective of the present study was to evaluate the occurrence of systolic dysfunction in dogs with MMVD through pharmacological stress test with dobutamine. The dogs were distributed in three groups: G1 (n = 8) control group, G2 (n = 7) animals with MMVD and left ventricular diastolic diameter indexed to the aorta (LVIDd:Ao) < 2.37 and G3 (n = 6) animals with MMVD and LVIDd:Ao ≥ 2.37. The echocardiograph was performed before (T0) and after (T1) continuous infusion of dobutamine, as follows: 5μg/kg/minute for five minutes and 10μg/kg/minute for 10 minutes (T1). The results were evaluated by Tukey test with significance level of 5% for the following variables: ejection fraction (EF%) (mean percentage variation (MPV) of EF% before and after dobutamine infusion), MPV of shortening fraction FS% and internal diameters of left ventricle in systole and in diastole indexed by aortic diameter (LVIDs:Ao and LVIDd:Ao). The results about the MPV FS% and the MPV EF% showed that there was statistical difference between the G1 and G3 groups, as well as between G2 and G3, while the G1 and G3 differed statistically from the G1 and G3 groups. On the other hand, there was no significant difference (p> 0.05) for the averages obtained before and after dobutamine of the FS% and EF% among all groups, however, there was a significant difference between groups G1 and G2 when the T0 moments and T1. In addition, it was concluded that there were differences between the G1 and G3 groups as well as between G2 and G3 (p <0.05). Also, by means of the LVIDd:Ao means, it was concluded that there was a difference between the G1 and G3 groups as well as between G2 and G3 (p <0.05). In it’s turn, the means obtained from LVIDs:Ao differed significantly (p <0.05) in all groups before (T0) and post-dobutamine (T1), except in G3. Among the groups, the averages at T0, have significant statistical difference between the G1 and G3 groups (p <0.05). In addition, with respect to ESV/m², within the groups there was a significant difference only between G1 and G3. Among the times, only G1 showed differences between T0 and T1. Finally, statistical significance (p <0.05) was found when DIVEd / Ao correlated with MPV FS% and EF%, demonstrating that the higher the LVIDd:Ao the lower these variables. Therefore, it was determined that dobutamine can point to systolic dysfunction in animals with MMVD, especially those showing greater remodeling (G3), also inferring a strong relationship between LVIDd:Ao size and systolic dysfunction. Furthermore, in animals with less left ventricular (LV) remodeling, such as those in group G2, inotropic response to pharmacological challenge was satisfactory, revealing the presence of contractile reserve in these patients. To conclude, dobutamine stress test showed effective, safe and applicable in clinical routine.
Myxomatous mitral valve disease (MMVD) is the most common cardiopathy in small animals, which evolution may result in important hemodynamic changes due to compensatory neurohormonal mechanisms. Although its diagnosis is relatively simple, intrinsic changes may be underestimated by conventional exams, as systolic dysfunction and myocardial reserve that may go unnoticed by echocardiograph. Therefore, the objective of the present study was to evaluate the occurrence of systolic dysfunction in dogs with MMVD through pharmacological stress test with dobutamine. The dogs were distributed in three groups: G1 (n = 8) control group, G2 (n = 7) animals with MMVD and left ventricular diastolic diameter indexed to the aorta (LVIDd:Ao) < 2.37 and G3 (n = 6) animals with MMVD and LVIDd:Ao ≥ 2.37. The echocardiograph was performed before (T0) and after (T1) continuous infusion of dobutamine, as follows: 5μg/kg/minute for five minutes and 10μg/kg/minute for 10 minutes (T1). The results were evaluated by Tukey test with significance level of 5% for the following variables: ejection fraction (EF%) (mean percentage variation (MPV) of EF% before and after dobutamine infusion), MPV of shortening fraction FS% and internal diameters of left ventricle in systole and in diastole indexed by aortic diameter (LVIDs:Ao and LVIDd:Ao). The results about the MPV FS% and the MPV EF% showed that there was statistical difference between the G1 and G3 groups, as well as between G2 and G3, while the G1 and G3 differed statistically from the G1 and G3 groups. On the other hand, there was no significant difference (p> 0.05) for the averages obtained before and after dobutamine of the FS% and EF% among all groups, however, there was a significant difference between groups G1 and G2 when the T0 moments and T1. In addition, it was concluded that there were differences between the G1 and G3 groups as well as between G2 and G3 (p <0.05). Also, by means of the LVIDd:Ao means, it was concluded that there was a difference between the G1 and G3 groups as well as between G2 and G3 (p <0.05). In it’s turn, the means obtained from LVIDs:Ao differed significantly (p <0.05) in all groups before (T0) and post-dobutamine (T1), except in G3. Among the groups, the averages at T0, have significant statistical difference between the G1 and G3 groups (p <0.05). In addition, with respect to ESV/m², within the groups there was a significant difference only between G1 and G3. Among the times, only G1 showed differences between T0 and T1. Finally, statistical significance (p <0.05) was found when DIVEd / Ao correlated with MPV FS% and EF%, demonstrating that the higher the LVIDd:Ao the lower these variables. Therefore, it was determined that dobutamine can point to systolic dysfunction in animals with MMVD, especially those showing greater remodeling (G3), also inferring a strong relationship between LVIDd:Ao size and systolic dysfunction. Furthermore, in animals with less left ventricular (LV) remodeling, such as those in group G2, inotropic response to pharmacological challenge was satisfactory, revealing the presence of contractile reserve in these patients. To conclude, dobutamine stress test showed effective, safe and applicable in clinical routine.
Descrição
Palavras-chave
ecocardiografia, endocardiose, disfunção sistólica, insuficiência mitral, estresse farmacológico, echocardiography, endocardiosis, systolic dysfunction, mitral valve insufficiency, pharmacological stress