Avaliação da variabilidade da frequencia cardíaca (VFC) em cão da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) / Evaluation of heart rate variability (HRV) in a Boxer dog with arrhythmogenic right ventricle cardiomyopathy (ARVC)

Background: Boxer dog cardiomyopathy was initially described by Neil Harpster in 1983 and has received different names. However, several recent studies demonstrated a similarity to the human arrhythmogenic right ventricular cardiomyopathy (ARVC), which led to the name Boxer ARVC. This hereditary disease seems to be linked to a mutation in the gene that codifies the cardiac ryanodine receptor. This mutation leads to an alteration of the calcium cycle in the heart. The analysis of the heart rate variability is an important predictive factor for diagnosing this disease. Therefore, this study aims to report a case of a Boxer ARVC providing electrocardiographic data and heart rate variability.Case: A 11 year-old male Boxer dog, weighting 29.65 kg, was submitted to a heart check-up due to sudden occurrence of fatigue and syncope. At the clinical examination, heart auscultation did not revealed sounds or arrhythmias. The electrocardiogram results presented tachycardia and a regular rhythm with ventricular premature complexes (VPC´s). Ecodopplercargiogram was performed and values were within normal standards. Thus, a dynamic monitoring of 24 h was performed using a Holter monitor. This analysis demonstrated tachycardia in the sinus rhythm, type I second degree sinoatrial block, normal PR interval and normal length of QRS complexes. In addition, severe ventricular ectopy was identified in the following forms: isolated, paired, and nonsustained ventricular tachycardia. The heart rate variability analysis resulted in mean values of 213 ms (SNDD), 132 ms (SDANN), 211ms (rMSSD) and 33.46% (pNN50). Based on these data, Boxer ARVC is the probable diagnosis. However, a ventricular myocardial biopsy necessary to confirm the disease was not performed due to the inherent risk of the procedure. Treatment was performed with sotalol and a commercial feed specially designed for dogs with for cardiac diseases.[...](AU)

Avaliação da variabilidade da frequencia cardíaca (VFC) em cão da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) / Evaluation of heart rate variability (HRV) in a Boxer dog with arrhythmogenic right ventricle cardiomyopathy (ARVC)

Background: Boxer dog cardiomyopathy was initially described by Neil Harpster in 1983 and has received different names. However, several recent studies demonstrated a similarity to the human arrhythmogenic right ventricular cardiomyopathy (ARVC), which led to the name Boxer ARVC. This hereditary disease seems to be linked to a mutation in the gene that codifies the cardiac ryanodine receptor. This mutation leads to an alteration of the calcium cycle in the heart. The analysis of the heart rate variability is an important predictive factor for diagnosing this disease. Therefore, this study aims to report a case of a Boxer ARVC providing electrocardiographic data and heart rate variability.Case: A 11 year-old male Boxer dog, weighting 29.65 kg, was submitted to a heart check-up due to sudden occurrence of fatigue and syncope. At the clinical examination, heart auscultation did not revealed sounds or arrhythmias. The electrocardiogram results presented tachycardia and a regular rhythm with ventricular premature complexes (VPC´s). Ecodopplercargiogram was performed and values were within normal standards. Thus, a dynamic monitoring of 24 h was performed using a Holter monitor. This analysis demonstrated tachycardia in the sinus rhythm, type I second degree sinoatrial block, normal PR interval and normal length of QRS complexes. In addition, severe ventricular ectopy was identified in the following forms: isolated, paired, and nonsustained ventricular tachycardia. The heart rate variability analysis resulted in mean values of 213 ms (SNDD), 132 ms (SDANN), 211ms (rMSSD) and 33.46% (pNN50). Based on these data, Boxer ARVC is the probable diagnosis. However, a ventricular myocardial biopsy necessary to confirm the disease was not performed due to the inherent risk of the procedure. Treatment was performed with sotalol and a commercial feed specially designed for dogs with for cardiac diseases.[...]

Arrhythmogenic Right Ventricular Cardiomyopathy in Two Dogs

Arrhythmogenic right ventricle cardiomyopathy (ARVC) is a rare primary heart condition recognized in dogs. It is an inherited disease more commonly described in Boxer dogs. Clinically, ARVC is characterized by ventricular tachyarrhythmias and histopathologically by fibrofatty replacement, mostly on the right ventricle. This report describes the gross and histopathological findings from a female adult Boxer and from a male adult mixed breed dog, presenting signs of heart failure and marked infiltration of adipose tissue replacing cardiomyocytes, predominantly in the epicardium and myocardium of the right ventricle.

Arrhythmogenic Right Ventricular Cardiomyopathy in Two Dogs

Arrhythmogenic right ventricle cardiomyopathy (ARVC) is a rare primary heart condition recognized in dogs. It is an inherited disease more commonly described in Boxer dogs. Clinically, ARVC is characterized by ventricular tachyarrhythmias and histopathologically by fibrofatty replacement, mostly on the right ventricle. This report describes the gross and histopathological findings from a female adult Boxer and from a male adult mixed breed dog, presenting signs of heart failure and marked infiltration of adipose tissue replacing cardiomyocytes, predominantly in the epicardium and myocardium of the right ventricle.(AU)

AVALIAÇÃO ECOCARDIOGRÁFICA DA FUNÇÃO DO VENTRÍCULO DIREITO DE CÃES DA RAÇA BOXER COM CARDIOMIOPATIA ARRITMOGÊNICA DO VENTRÍCULO DIREITO: ESTUDO CASO-CONTROLE

A cardiomiopatia arritmogênica do ventrículo direito (CAVD) é uma doença de origem genética, muito prevalente em cães da raça Boxer. Histologicamente ocorre atrofia dos cardiomiócitos do ventrículo direito (VD) e consequente infiltração fibroadiposa, levando ao aparecimento de arritmias ventriculares. Mesmo sendo as alterações miocárdicas microscópicas em sua maioria, estudos recentes têm identificado disfunção contrátil do ventrículo direito, mesmo em estágios iniciais da doença em humanos, tanto por técnicas convencionais de ecocardiografia quanto por técnicas mais avançadas, como no caso do speckle tracking. Por isso, o objetivo deste estudo foi avaliar se há disfunção miocárdica de VD detectável pela ecocardiografia convencional e pela técnica de speckle tracking bidimensional em cães da raça Boxer portadores da CAVD. Para tanto, utilizou-se cães da raça Boxer com idade superior a quatro anos, distribuídos em dois grupos de acordo com o resultado da avaliação Holter (GC: < 50 EVs/24h, n=11 e GD: > 100 EVs/24h, n=11). Os animais foram submetidos a ecocardiografia e avaliou-se diâmetro e comprimento interno do VD em sístole e diástole, encurtamento fracional da área do VD (FAC), excursão sistólica do plano anular da tricúspide (TAPSE), velocidade miocárdica sistólica do ânulo lateral da tricúspide derivada do Doppler tecidual (S) e deformação (strain) e taxa de deformação (strain rate) longitudinal global da parede livre do VD, derivados da análise por speckle tracking. As variáveis foram comparadas entre os grupos pelo teste t de Student e de Mann-Whitney e a correlação entre variáveis ecocardiográficas convencionais e de speckle tracking e o número e severidade das arritmias pelo teste de correlação de Pearson, com nível de significância de 5%. Os grupos não foram estatisticamente diferentes e não houve correlação entre os dados. Os resultados da pesquisa demonstraram que a ecocardiografia, tanto na avaliação do VD por índices sistólicos convencionais quanto por aqueles derivados da técnica de speckle tracking não foram capazes de detectar disfunção miocárdica do VD em Boxers portadores de CAVD.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disease with a high prevalence in Boxer dogs. Histologically, right ventricle (RV) cardiomyocytes atrophy occurs, and thus fibrofatty infiltration, triggering ventricular arrhythmias. Although the myocardial changes are mostly microscopic, recent studies in human beings have identified right ventricular systolic dysfunction even in the early stages of ARVC, both by conventional echocardiographic techniques and advanced methods, such as speckle tracking. Therefore, the aim of this study was to investigate if RV myocardial dysfunction is present in Boxers affected by ARVC, evaluated by conventional echocardiography and bidimensional speckle tracking technique. For this purpose, Boxers older than four years were recruited, and based on 24-hour Holter recording were divided in groups: GC:< 50 VPC/24h (n=11), or GD: > 100 VPC/24h (n=11). The following echocardiographic parameters were analyzed: RV internal dimension during systole and diastole; RV fractional area change (FAC); tricuspid annular plane systolic excursion (TAPSE); myocardial systolic velocity of lateral tricuspid annulus (S), and global longitudinal strain and strain rate. Groups were compared by Student t-test or Mann-Whitney test according distribution, and correlation between conventional and speckle tracking echocardiographic variables, as well as number and severity of the ventricular arrhythmias were accomplished by the Pearson test, assuming a level of significance at 5%. Groups were considered similar, and there was no correlation among the evaluated parameters. Our findings suggesting that the echocardiographic evaluation of RV, either by conventional and speckle tracking techniques, were not able to detect systolic myocardial dysfunction in Boxers affected by ARVC.