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.

Sensibilidade e especificidade do exame eletrocardiográfico na detecção de sobrecargas atriais e/ou ventriculares em gatos da raça Persa com cardiomiopatia hipertrófica / Sensitivity and specificity of electrocardiographic examination in detecting ventricular or atrial overloads in Persian cats with hypertrophic cardiomyopathy

A cardiomiopatia hipertrófica (CMH) é a principal cardiopatia dos felinos e é caracterizada por hipertrofia miocárdica concêntrica, sem dilatação ventricular. O ecocardiograma é o melhor meio diagnóstico não invasivo para a diferenciação das cardiomiopatias e é considerado padrão ouro para a detecção de hipertrofia ventricular presente na CMH. Alterações eletrocardiográficas também são comuns em animais com CMH e o eletrocardiograma (ECG) é um teste de triagem para detecção de hipertrofia ventricular em humanos, sendo um exame rápido e facilmente disponível. Em gatos, poucos estudos foram realizados quanto à sensibilidade e especificidade do ECG na detecção de hipertrofia ventricular. Com a intenção de avaliar o uso do ECG como ferramenta de triagem para diagnóstico de CMH em felinos, gatos da raça Persa (n=82) foram avaliados por meio de exames ecocardiográfico e eletrocardiográfico. Animais com bloqueios e/ou distúrbios de condução foram excluídos da análise estatística (n=22). Posteriormente, os animais incluídos foram classificados em: normais (n=38), suspeitos (n=6) e acometidos pela CMH (n=16). Observaram-se diferenças estatísticas na amplitude da onda P em DII e na amplitude de onda R em DII, CV6LL e CV6LU, com valores maiores nos animais com CMH; e nos valores ecocardiográficos de velocidade e gradiente de pressão do fluxo aórtico, diâmetro do átrio esquerdo (AE) e relação AE/Ao, com valores maiores nos gatos com CMH. Dentre os animais com alterações eletrocardiográficas sugestivas de sobrecarga atrial esquerda (n=7), apenas dois realmente apresentavam aumento do AE no ecocardiograma; e dentre os animais com aumento atrial esquerdo ao ecocardiograma (n=7), apenas dois apresentavam alterações eletrocardiográficas sugestivas de sobrecarga do AE (sensibilidade de 40,40% e especificidade de 90,90%). Dentre os gatos com alterações eletrocardiográficas sugestivas de sobrecarga ventricular esquerda (n=6), cinco realmente apresentavam hipertrofia ventricular ao ecocardiograma; e dentre os animais com CMH ao ecocardiograma (n=16), apenas cinco apresentaram alterações eletrocardiográficas sugestivas de sobrecarga do VE (sensibilidade de 31,25% e especificidade de 97,72%). Observou-se correlação positiva entre espessura diastólica do septo interventricular e/ou da parede livre do ventrículo esquerdo e a amplitude da onda R em derivações DII e CV6LU. O eletrocardiograma é um exame rápido e de fácil execução, apresenta boa especificidade na detecção de hipertrofia ventricular em felinos, porém, possui baixa sensibilidade, com grande número de falsos negativos. Desta forma, o ECG auxilia no diagnóstico, mas não substitui o ecocardiograma na confirmação da hipertrofia ventricular.(AU)

Hypertrophic cardiomyopathy (HCM) is the most common feline heart disease and is characterized by increased cardiac mass with a hypertrophied and not dilated left ventricle. The echocardiography is the best noninvasive diagnostic tool for the differentiation of cardiomyopathies and is considered the gold standard for detection of ventricular hypertrophy present in HCM. Electrocardiographic changes are also common in animals with HCM and the electrocardiogram (ECG) is quick, easy and highly available screening test for the detection of ventricular hypertrophy in humans. In cats, few studies have been conducted regarding the sensitivity and specificity of ECG in detecting ventricular hypertrophy. With the intention of evaluating the use of ECG as a screening tool for diagnosis of HCM in cats, Persian cats (n=82) were evaluated by echocardiographic and electrocardiographic examinations. Animals with blocks and/or conduction disturbances were excluded from statistical analysis (n=22). Subsequently the animals included were classified as normal (n=38), suspicious (n=6) and affected by HCM (n=16). Statistical differences were observed in the P-wave amplitude in DII and R-wave amplitude in DII, CV6LL and CV6LU, with higher values in animals with HCM. Velocities and pressure gradient of aortic flow, left atrial diameter (LA) and LA/Ao ratio were higher in cats with HCM. Among the animals with ECG changes suggestive of left atrial enlargement (n=7), only two actually had LA enlargement on echocardiography, and among animals with left atrial enlargement on echocardiogram (n=7), only two had ECG changes suggestive of overload AE (40,4% of sensibility and 90,9% of specificity). Among the animals with ECG changes suggestive of left ventricular hypertrophy (n=6), five actually had ventricular hypertrophy on echocardiography, and among animals with HCM by echocardiography (n=16), only five showed electrocardiographic abnormalities suggestive of LV hypertrophy (31,25% of sensibility and 97,72% of specificity). We observed a positive correlation between diastolic thickness of the interventricular septum and/or left ventricular free wall and R-wave amplitude in DII and CV6LU. The electrocardiogram is quick and easy to perform, has good specificity in detecting ventricular hypertrophy in cats, however, has low sensitivity, with large numbers of false negative animals. Thus, the ECG assists in the diagnosis, but does not replace echocardiography in confirming ventricular hypertrophy.(AU)

Sensibilidade e especificidade do exame eletrocardiográfico na detecção de sobrecargas atriais e/ou ventriculares em gatos da raça Persa com cardiomiopatia hipertrófica / Sensitivity and specificity of electrocardiographic examination in detecting ventricular or atrial overloads in Persian cats with hypertrophic cardiomyopathy

A cardiomiopatia hipertrófica (CMH) é a principal cardiopatia dos felinos e é caracterizada por hipertrofia miocárdica concêntrica, sem dilatação ventricular. O ecocardiograma é o melhor meio diagnóstico não invasivo para a diferenciação das cardiomiopatias e é considerado padrão ouro para a detecção de hipertrofia ventricular presente na CMH. Alterações eletrocardiográficas também são comuns em animais com CMH e o eletrocardiograma (ECG) é um teste de triagem para detecção de hipertrofia ventricular em humanos, sendo um exame rápido e facilmente disponível. Em gatos, poucos estudos foram realizados quanto à sensibilidade e especificidade do ECG na detecção de hipertrofia ventricular. Com a intenção de avaliar o uso do ECG como ferramenta de triagem para diagnóstico de CMH em felinos, gatos da raça Persa (n=82) foram avaliados por meio de exames ecocardiográfico e eletrocardiográfico. Animais com bloqueios e/ou distúrbios de condução foram excluídos da análise estatística (n=22). Posteriormente, os animais incluídos foram classificados em: normais (n=38), suspeitos (n=6) e acometidos pela CMH (n=16)...

Hypertrophic cardiomyopathy (HCM) is the most common feline heart disease and is characterized by increased cardiac mass with a hypertrophied and not dilated left ventricle. The echocardiography is the best noninvasive diagnostic tool for the differentiation of cardiomyopathies and is considered the gold standard for detection of ventricular hypertrophy present in HCM. Electrocardiographic changes are also common in animals with HCM and the electrocardiogram (ECG) is quick, easy and highly available screening test for the detection of ventricular hypertrophy in humans. In cats, few studies have been conducted regarding the sensitivity and specificity of ECG in detecting ventricular hypertrophy. With the intention of evaluating the use of ECG as a screening tool for diagnosis of HCM in cats, Persian cats (n=82) were evaluated by echocardiographic and electrocardiographic examinations. Animals with blocks and/or conduction disturbances were excluded from statistical analysis (n=22). Subsequently the animals included were classified as normal (n=38), suspicious (n=6) and affected by HCM (n=16)...

Doppler echocardiographic evaluation of midventricular obstruction in cats with hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is heterogeneous in both people and cats, with variability in the distribution of hypertrophy, hemodynamic characteristics, and Doppler echocardiographic findings. OBJECTIVES: To document the Doppler echocardiographic characteristics of midventricular obstruction in some cats with HCM. ANIMALS: Eight cats with hypertrophic cardiomyopathy. MATERIALS AND METHODS: Retrospective case series. The medical records of cats presenting to the cardiology service at Colorado State University between February 2009 and January 2012 were reviewed. All cats had a physical examination; Doppler systolic blood pressure measurement; and transthoracic two-dimensional (2D), M-mode, and Doppler echocardiography were performed. A more thorough evaluation of the echocardiographic images and measurements was performed. Cats included in this study had echocardiograms of adequate quality to confirm the diagnosis of midventricular obstruction by documentation of left midventricular concentric hypertrophy; a midventricular turbulent Doppler color flow pattern; and high velocity, late-peaking flow at the area of turbulence. Cats with evidence of systemic hypertension defined as a systolic Doppler blood pressure of greater than 170 mmHg were excluded. RESULTS: All 8 cats had left ventricular hypertrophy at the level of the papillary muscles; left, midventricular hypertrophy; and in 4/8 cats there was apical hypertrophy or basilar hypertrophy of the interventricular septum. Color flow Doppler revealed turbulent flow in 8/8 cats and spectral Doppler (continuous and pulsed wave) revealed increased flow velocities and late-peaking flow profiles at the level of the left midventricle. Two of 8 cats had a bifid midventricular flow profile in which there was a midsystolic decline in left ventricular velocities with elevated velocities extending into early diastole. The peak left ventricular outflow velocity in all 8 cats was normal. CONCLUSIONS AND CLINICAL IMPORTANCE: A variant of HCM characterized by hypertrophy at the level of the papillary muscles with midventricular obstruction is present in some cats. Recognition of this variant of feline HCM allows identification of HCM in cats with murmurs where the more classic features of HCM are not present.

Endocardial fibroelastosis in a dog.

Endocardial fibroelastosis is an uncommon congenital heart disease in dogs that may be manifested by signs of left-sided congestive heart failure. A three-month-old, male, Fila Brasileiro dog developed signs of generalised heart failure. Physical examination revealed normal temperature, ascites, and pale and cyanotic mucous membranes. The pup died just after radiography which revealed ascites, hepatomegaly, severe cardiac enlargement and pulmonary oedema. At necropsy, serosanguineous fluid in the thorax and abdomen, pulmonary oedema, right ventricular dilatation, hypertrophy and dilatation of the left ventricle, and mitral valve incompetence were observed. The histopathological examination demonstrated that the thickening of the endocardium of the left atrium and left ventricle was due to the presence of elastic and collagen fibres, although there were no signs of an inflammatory process.