Exercise training of dogs with myxomatous valve disease / Treinamento físico de cães com doença mixomatosa valvar

The present study has the objective of evaluating the effects of exercise training, using moderate intensity walking (60 to 80% of maximum heart rate), from 30 to 50 minutes, three times a week, in alternate days, during eight weeks, on heart rate variability in dogs with myxomatous valve disease (MVD). For that, 20 dogs in stages B1 (1), B2 (14) and C2 (5) of MVD (ACVIM classification) were divided into untrained control group (CG, n=9) and training group (TG, n=11), and assessed at baseline (T0), after four (T1) and eight weeks (T2). Only one B1 and five B2 dogs completed the training program. In the time domain, the rMSSD was greater in TG in T1 (155,5+42,07) and T2 (199,8+83,54) than CG (T1:91,17+35,79 and T2:88,17+57,51). In the frequency domain, the variable High Frequency (HF) increased in TG in T1 (30950+25810) and T2 (40300+33870) when compared to the CG (T1:19090+23210 and T2:18810+22200) and within the group TG in T2 in relation to T0 (29340+20950). The proposed walking protocol is concluded to have increased the rMSSD and HF variables in TG, representing an increase of the parasympathetic tonus, justifying the indication of this therapy in B1 and B2 stages of MVD.(AU)

O presente estudo objetivou avaliar o efeito do treinamento físico, utilizando-se a caminhada de moderada intensidade (60 a 80% da frequência cardíaca máxima), por 30 a 50 minutos, três vezes por semana, em dias alternados, durante oito semanas, sobre a variabilidade da frequência cardíaca em cães com degeneração mixomatosa valvar (DMV). Para tanto, 20 cães nos estágios B1 (1), B2 (14) e C2 (5) da DMV (classificação ACVIM) foram divididos em grupo controle não treinado (GC, n=9) e grupo treinamento (GT, n=11) e avaliados no início do estudo (T0), após quatro (T1) e oito semanas (T2). Apenas um cão B1 e cinco B2 completaram o programa de treinamento. No domínio do tempo, a variável rMSSD foi maior no GT em T1 (155,5+42,07) e T2 (199,8+83,54) que o GC (T1:91,17+35,79 e T2:88,17+57,51). No domínio da frequência, a variável High Frequency (HF) aumentou no GT em T1 (30950+25810) e T2 (40300+33870) comparada à do GC (T1:19090+23210 e T2:18810+22200), e dentro do GT no T2 em relação ao T0 (29340+20950). Dessa forma, conclui-se que o protocolo de treinamento proposto aumentou as variáveis rMSSD e HF no GT, representando aumento do tônus parassimpático, o que fundamenta a indicação dessa terapia nos estágios B1 e B2 da DMV.(AU)

Value of quantitative tissue velocity imaging in the detection of regional myocardial function in dogs with acute subendocardial ischemia / 华中科技大学学报（医学）（英德文版）

This study evaluated the application of quantitative tissue velocity imaging (QTVI) in assessing regional myocardial systolic and diastolic functions in dogs with acute subendocardial ischemia. Animal models of subendocardial ischemia were established by injecting microspheres (about 300 microm in diameter) into the proximal end of left circumflex coronary artery in 11 hybrid dogs through cannulation. Before and after embolization, two-dimensional echocardiography, QTVI and real-time myocardial contrast echocardiography (RT-MCE) via intravenous infusion of self-made microbubbles, were performed, respectively. The systolic segmental wall thickening and subendocardial myocardial longitudinal velocities of risk segments before and after embolization were compared by using paired t analysis. The regional myocardial video intensity versus contrast time could be fitted to an exponential function: y=A.(1-exp(-beta.t)), in which the product of A and beta provides a measure of myocardial blood flow. RT-MCE showed that subendocardial normalized A.beta was decreased markedly from 0.99+/-0.19 to 0.35+/-0.11 (P0.05), the longitudinal peak systolic velocities (Vs) and early-diastolic peak velocities (Ve) recorded by QTVI were declined significantly (P<0.05). Moreover, the subendocardial velocity curves during isovolumic relaxation predominantly showed positive waves, whereas they mainly showed negative waves before the embolization. This study demonstrates that QTVI can more sensitively and accurately detect abnormal regional myocardial function and post-systolic systole caused by acute subendocardial ischemia.