Pressure-induced left ventricular hypertrophy in canine model of aortic stenosis using nylon tie

The aim of this study was to develop an experimentally-induced canine model of left ventricular hypertrophy through banding of the ascending aorta using nylon ties. Seven clinically normal dogs free of cardiovascular disease were used. Nylon tie was used in banding the mid-ascending aorta. Clinical, radiographic and echocardiographic evaluations were done at 1.5, 3 and 6 months. Dogs were euthanized at 6 months for post mortem and histopathological evaluation. Clinically, dogs did not exhibit any signs of cardiovascular disease at 1.5 or 3 months, while at 6 months two dogs (28.6 %) exhibited mild weight loss, exercise intolerance and heart murmurs. Radiographic evaluation revealed significant increase in cardiac size only at 6 months based on measurement of the cardiothoracic area evaluation. Echocardiography revealed increased left ventricular wall thickness starting from 1.5 month, although this increase was statistically significant at 3 and 6 months (p > 0.05). Left ventricular hypertrophy was confirmed by post mortem examination. Histopathological sections of left ventricle in all dogs demonstrated myocyte hypertrophy and interstitial fibrosis. This model simulates the naturally occurring ventricular hypertrophy using a rapid and economic technique. Such models are required to understand pathogenesis of heart disease and to develop effective treatment strategy.

Age, sex and body weight related echocardiographic parameters of clinically healthy New Zealand white rabbits

Background: Echocardiography provides useful additional information on cardiac dimensions including heart wall anddimension of the ventricles, atria and conditions. Rabbits have been diagnosed with cardiac diseases, and an understandingof the animals’ cardiac chamber dimensions is vital in assessing the diseases’ severity and prognoses. Changes in cardiacdimensions due to age related and body weight were determined at different animals. The increased incidence of congenitalcardiovascular anomalies makes it essential to establish the diagnosis at an early age. The aims of this study 1) establishnormal values for the commonly used two-dimensional (2D) M-mode parameters using pre anaesthetics and 2) evaluatethe effects of age, sex, and body weight on echocardiographic parameters in clinically healthy New Zealand rabbits.Materials, Methods & Results: In this study we used 49 New Zealand white rabbits (25 male, 24 female) all reared under the same conditions. A general physical and clinical examination including complete blood count was performed foreach animal. Body surface area was calculated as BSA= 0.00718 × Height 0.725 × Weight 0.425. Rabbits were sedated withmidazolam before echocardiographic examination was performed. Echocardiographic examination was performed using aDC 6-Vet® (Mindray, PRC) ultrasonographic device equipped with a micro-convex 8 MHz probe. Right parasternal shortaxis view, B-mode and two-dimensional guided M-mode parameters were measured. Echocardiographic measurementswere performed using leading-edge-to-leading-edge conventions outlined by the American Society of Echocardiography.Statistical analyses were employed using the SPSS 19.0 program. Sex had no significant effect on the measured echocardiographic parameters except in the case of interventricular septum thickness in diastole values of the three-month-oldrabbits. The increase in the left ventricular systolic and diastolic diameters...

Age, sex and body weight related echocardiographic parameters of clinically healthy New Zealand white rabbits

Background: Echocardiography provides useful additional information on cardiac dimensions including heart wall anddimension of the ventricles, atria and conditions. Rabbits have been diagnosed with cardiac diseases, and an understandingof the animals cardiac chamber dimensions is vital in assessing the diseases severity and prognoses. Changes in cardiacdimensions due to age related and body weight were determined at different animals. The increased incidence of congenitalcardiovascular anomalies makes it essential to establish the diagnosis at an early age. The aims of this study 1) establishnormal values for the commonly used two-dimensional (2D) M-mode parameters using pre anaesthetics and 2) evaluatethe effects of age, sex, and body weight on echocardiographic parameters in clinically healthy New Zealand rabbits.Materials, Methods & Results: In this study we used 49 New Zealand white rabbits (25 male, 24 female) all reared under the same conditions. A general physical and clinical examination including complete blood count was performed foreach animal. Body surface area was calculated as BSA= 0.00718 × Height 0.725 × Weight 0.425. Rabbits were sedated withmidazolam before echocardiographic examination was performed. Echocardiographic examination was performed using aDC 6-Vet® (Mindray, PRC) ultrasonographic device equipped with a micro-convex 8 MHz probe. Right parasternal shortaxis view, B-mode and two-dimensional guided M-mode parameters were measured. Echocardiographic measurementswere performed using leading-edge-to-leading-edge conventions outlined by the American Society of Echocardiography.Statistical analyses were employed using the SPSS 19.0 program. Sex had no significant effect on the measured echocardiographic parameters except in the case of interventricular septum thickness in diastole values of the three-month-oldrabbits. The increase in the left ventricular systolic and diastolic diameters...(AU)

Long-axis fractional shortening and mitral annulus motion in dogs / Fração de encurtamento longitudinal e movimento anular mitralem cães

Ventricular systolic dynamics involves the contraction of transverse and longitudinal myocardial fibers. Unfortunately, only the activity of the transverse myocardial fibers is foreseen by the standard systolic echocardiographic parameters. Although strain and strain rate have been used to assess the radial, circumferential and longitudinal planes of cardiac contraction, such analysis requires advanced equipment which is not always available in veterinary medicine. On the contrary, some unusual parameters may be recorded via standard methodology, allowing for the specific evaluation of left ventricular longitudinal contractility. In this study, the longitudinal contractile activity was evaluated using the long-axis fractional shortening and the mitral annulus motion, which were compared with several standard echocardiographic parameters in 14 beagles, including seven with asymptomatic mitral valve disease. The long-axis fractional shortening was positively correlated with both the mitral annulus motion and the end-diastolic left-ventricular diameter. Also, a significant correlation was found to exist between the mitral annulus motion and the left-ventricular end-diastolic diameter, which is likely supportive of its preload dependency. Even though no difference was documented in either mitral annulus motion or long-axis fractional shortening between healthy dogs and dogs with mitral valve disease, the latter only included animals with minimal cardiac remodeling, with no overt compromiseof systolic function. Since it is possible to obtain these two parameters with any echocardiographic equipment, their inclusion in the routine exam would probably add information regarding the activity of the longitudinal myocardial fibers, whose functional deterioration supposedly occurs prior to theimpairment of transverse fibers.

A dinâmica ventricular sistólica envolve a contração de fibras miocárdicas transversais e longitudinais e, infelizmente, os parâmetros ecocardiográficos de função sistólica utilizados rotineiramente estão focados apenas na atividade das fibras transversais. Embora a deformação e a taxa de deformação miocárdicas venham sendo utilizadas para avaliar a contração cardíaca nos planos radial, circunferencial e longitudinal, tal análise requer equipamentos avançados que nem sempre estão disponíveis na Medicina Veterinária. Por outro lado, alguns parâmetros não usuais podem ser quantificados valendo-se de metodologia convencional, permitindo avaliar especificamente a função contrátil longitudinal do ventrículo esquerdo. Neste estudo, a atividade contrátil longitudinal foi avaliada por meio da fração de encurtamento longitudinal e do movimento anular mitral, os quais foram comparados com diversas variáveis ecocardiográficas convencionais em 14 Beagles, sendo sete deles portadores de doença valvar mitral assintomática. A fração de encurtamento longitudinal apresentou correlação positiva com o movimento anular mitral e com o diâmetro do ventrículo esquerdo em diástole. Também houve correlação significativa entre o movimento anular mitral e o diâmetro ventricular esquerdo em diástole, o que pode sugerir sua dependência da pré-carga. Embora não tenham sido observadas diferenças no movimento anular mitral e na fração de encurtamento longitudinal entre cães saudáveis e valvulopatas, há que se enfatizar que os animais com doença mitral apresentavam apenas mínimoremodelamento cardíaco, sem quaisquer indícios de comprometimento da função sistólica.

Long-axis fractional shortening and mitral annulus motion in dogs / Fração de encurtamento longitudinal e movimento anular mitralem cães

Ventricular systolic dynamics involves the contraction of transverse and longitudinal myocardial fibers. Unfortunately, only the activity of the transverse myocardial fibers is foreseen by the standard systolic echocardiographic parameters. Although strain and strain rate have been used to assess the radial, circumferential and longitudinal planes of cardiac contraction, such analysis requires advanced equipment which is not always available in veterinary medicine. On the contrary, some unusual parameters may be recorded via standard methodology, allowing for the specific evaluation of left ventricular longitudinal contractility. In this study, the longitudinal contractile activity was evaluated using the long-axis fractional shortening and the mitral annulus motion, which were compared with several standard echocardiographic parameters in 14 beagles, including seven with asymptomatic mitral valve disease. The long-axis fractional shortening was positively correlated with both the mitral annulus motion and the end-diastolic left-ventricular diameter. Also, a significant correlation was found to exist between the mitral annulus motion and the left-ventricular end-diastolic diameter, which is likely supportive of its preload dependency. Even though no difference was documented in either mitral annulus motion or long-axis fractional shortening between healthy dogs and dogs with mitral valve disease, the latter only included animals with minimal cardiac remodeling, with no overt compromiseof systolic function. Since it is possible to obtain these two parameters with any echocardiographic equipment, their inclusion in the routine exam would probably add information regarding the activity of the longitudinal myocardial fibers, whose functional deterioration supposedly occurs prior to theimpairment of transverse fibers.(AU)

A dinâmica ventricular sistólica envolve a contração de fibras miocárdicas transversais e longitudinais e, infelizmente, os parâmetros ecocardiográficos de função sistólica utilizados rotineiramente estão focados apenas na atividade das fibras transversais. Embora a deformação e a taxa de deformação miocárdicas venham sendo utilizadas para avaliar a contração cardíaca nos planos radial, circunferencial e longitudinal, tal análise requer equipamentos avançados que nem sempre estão disponíveis na Medicina Veterinária. Por outro lado, alguns parâmetros não usuais podem ser quantificados valendo-se de metodologia convencional, permitindo avaliar especificamente a função contrátil longitudinal do ventrículo esquerdo. Neste estudo, a atividade contrátil longitudinal foi avaliada por meio da fração de encurtamento longitudinal e do movimento anular mitral, os quais foram comparados com diversas variáveis ecocardiográficas convencionais em 14 Beagles, sendo sete deles portadores de doença valvar mitral assintomática. A fração de encurtamento longitudinal apresentou correlação positiva com o movimento anular mitral e com o diâmetro do ventrículo esquerdo em diástole. Também houve correlação significativa entre o movimento anular mitral e o diâmetro ventricular esquerdo em diástole, o que pode sugerir sua dependência da pré-carga. Embora não tenham sido observadas diferenças no movimento anular mitral e na fração de encurtamento longitudinal entre cães saudáveis e valvulopatas, há que se enfatizar que os animais com doença mitral apresentavam apenas mínimoremodelamento cardíaco, sem quaisquer indícios de comprometimento da função sistólica. (AU)

Assessment of longitudinal systolic function using Tissue Motion Annular Displacement and Global Longitudinal Strain in healthy dogs and dogs with mitral valve disease

Nessa dissertação foi avaliada a função sistólica longitudinal do ventrículo esquerdo em cães saudáveis e em cães com doença valvar mitral por meio do deslocamento tecidual do anel mitral (TMAD) e Strain Longitudinal Global (GLS). O TMAD é uma técnica de ecocardiografia baseada em Speckle Tracking que avalia a competência das fibras miocárdicas longitudinais por meio do deslocamento do anulo mitral em direção ao ápice durante a sístole ventricular. Para tanto, esse trabalho foi subdividido em introdução e dois capítulos. O primeiro capítulo investigou a utilização do TMAD como método diagnóstico da função longitudinal em cães saudáveis. Para isso, foram avaliados 153 cães de diversas raças, pesos e idades. Os resultados mostraram que o TMAD é uma excelente técnica para avaliação da função longitudinal em cães, com correlação com diversas variáveis de função sistólica obtidas pela ecocardiografia convencional e com o GLS, além de ser rapidamente executado e com baixa variabilidade intra e interobservador. No segundo capítulo, foram recrutados 126 cães em diversos estágios da doença valvar mitral e 46 cães saudáveis como grupo controle, a fim de comparar e avaliar o comportamento da função sistólica longitudinal durante a evolução da doença para quadros de insuficiência cardíaca. Os resultados mostraram que não houve disfunção sistólica longitudinal evidente com a progressão da doença valvar mitral, visto que os valores de TMAD foram maiores nos estágios B2 e no grupo sintomático que no grupo controle e no estágio B1 da referida afecção cardíaca. O TMAD e o GLS apresentaram boa repetibilidade e se correlacionaram com diversos parâmetros ecocardiográficos, como AE/Ao, diâmetro interno do ventrículo esquerdo em sístole e diástole, onda E mitral e relação E/TRIV, sugerindo que essas técnicas são influenciadas por pré e pós carga. O TMAD é uma técnica mais rápida para ser realizada e pode ser uma alternativa ao GLS para avaliar a função sistólica longitudinal em cães saudáveis e em cães com doença valvar mitral.

In this dissertation tissue motion annular displacement (TMAD) and global longitudinal strain (GLS) were used to assess the left ventricular longitudinal systolic function in healthy dogs and in dogs with mitral valve disease. TMAD is an echocardiography technique based on Speckle Tracking that evaluates the competence of the longitudinal myocardial fibers by displacement of the mitral annulus toward the apex during ventricular systole. This dissertation is subdivided in introduction and two chapters. The first chapter investigated the use of TMAD as a diagnostic method for evaluation of longitudinal function in healthy dogs. For this, 153 dogs of different breeds, varying body weights and ages were recruited. TMAD was demonstrated to be an excellent technique for the evaluation of longitudinal function in dogs. It correlated with GLS and with several surrogates of systolic function obtained by conventional echocardiography. Also, it was quickly obtained and had a low intra- and inter-observer variability. In the second chapter, 126 dogs at various stages of mitral valve disease and 46 healthy dogs as a control group were enrolled in order to compare and evaluate the behavior of longitudinal systolic function along the progression of mitral valve disease to a heart failure status. The results showed no evident longitudinal systolic dysfunction as the disease progressed. TMAD was higher in stage B2 and in the symptomatic dogs as compared to stage B1 and control groups. TMAD and GLS had a good repeatability and correlated with several echocardiographic parameters, such as LA/Ao, left ventricular internal diameter in systole and diastole, mitral E wave and E/IVRT, suggesting that changes in preload and afterload play a role in such parameters. TMAD is a faster technique to perform and may be an alternative to GLS to assess longitudinal systolic function in healthy dogs and in dogs with mitral valve disease.

Avaliação morfoquantitativa do miocárdio de ratos Wistar submetidos à subnutrição proteica e à dieta padrão de Moçambique nos períodos pré e pós-natal

O impacto da desnutrição não se processa da mesma maneira nos diversos órgãos e tecidos do organismo, promovendo alterações na estrutura corpórea geral. O coração não é isento das consequências catabólicas da desnutrição. Em Maputo (capital de Moçambique), comprova um aumento na incidência de desnutrição grave, o que faz com que proporcione uma das maiores taxas de mortalidade, chegando a 20%. O objetivo deste trabalho foi avaliar possíveis repercussões morfofuncionais nos cardiomiócitos constituintes dos ventrículos esquerdos de ratos Wistar. Para tanto, foram utilizadas as dietas hipoprotéica (contendo 5% de caseína, e que caracteriza estado de subnutrição - grupo S); padrão de Moçambique (cujo conteúdo proteico vegetal é extraído do amendoim grupo M) e protéica (com 20% de caseína, caracterizando o grupo nutrido ou controle - grupo N). Os animais S, M e N constituíram dois grupos de estudo, sendo avaliados aos 21 dias de vida (época do desmame), e aos 42 dias. Após o desmame, foram mensurados os parâmetros metabólicos de ingestão de água e alimentar, bem como os de excreção de fezes e urina. As amostras dos corações foram processadas com técnicas rotineiras de histologia e submetidas a colorações que permitiram evidenciar o colágeno. Os aspectos ultraestruturais do ventrículo esquerdo também foram analisados. Para as avaliações, os dados foram submetidos a uma Análise de Variância (ANOVA) com dois fatores (idade e dieta) e quando necessário aplicou-se pós-teste de Bonferroni ou Tukey. Os nossos resultados mostram que a subnutrição é capaz de modificar as propriedades biomecânicas do miocárdio, causando atraso no seu desenvolvimento. Quanto às dietas aqui empregadas, mostram que a dieta padrão de Moçambique não atende uma nutrição adequada em comparação ao grupo nutrido, dentro dos parâmetros analisados. Conclui-se que a dieta padrão de Moçambique tem seus efeitos deletérios da subnutrição, nos aspectos metabólicos, estruturais e ultraestruturais do ventrículo esquerdo.

The impact of malnutrition is not processed in the same way in various organs and tissues of the body, promoting changes in the general body structure. The heart is not exempt from the catabolic effects of malnutrition. In Maputo (Mozambique's capital), proves an increased incidence of severe malnutrition, providing one of the highest mortality rates, reaching 20%. The aim of this study was to evaluate possible morphological and functional repercussions of the cardiomyocytes of left ventricles from Wistar rats. Therefore, low protein diets were used (containing 5% casein, malnutrition group - S group); standard diet from Mozambique (the vegetable protein content was extracted from the peanut - group M) and protein diet (with 20% casein - fed/control group - N group). Animals S, M and N constituted two study groups and were evaluated at 21 days of life (time of weaning), and at 42 days. After weaning, the metabolic parameters of ingestion of water and food and the excretion of faeces and urine were measured. The samples of hearts were processed and subjected to histological techniques which emphasize collagen. Ultrastructural aspects of the left ventricle were analyzed. Data were subjected to analysis of variance (ANOVA) with two factors (age and diet) and when required Bonferroni or Tukey post-test were applied. Our results show that malnutrition is capable of modifying the biomechanical properties of the myocardium, causing delay in its development. As for diets employed here, show that the standard diet from Mozambique does not provide adequate nutrition when compared to control group within the parameters analyzed. It concludes that the standard diet from Mozambique has its deleterious effects of malnutrition, metabolic, structural and ultrastructural aspects of the left ventricle.