Risk of arrhythmias in dogs with structural heart disease / Potencial arrítmico de cardiopatias em cães

Presently, pet life expectancy is becoming longer and several diseases inherent to age have been diagnosed, with heart disease being a frequent finding. Although various heart diseases have different pathophysiologies, many morphological and hemodynamic changes can predispose patients to arrhythmias. The presence of arrhythmias can worsen the underlying heart disease and predispose patients to develop new alterations, making arrhythmia detection important for establishing adequate therapeutic protocols and a better prognosis. The present study aimed to determine the arrhythmias most frequently found in dogs treated at the Cardiology and Respiratory Diseases Service (SCDR) of the Small Animals Sector of the Veterinary Hospital of the Federal Rural University of Rio de Janeiro (UFRRJ), during the period from January to 2014 to December 2017, relating them to sex, age group, size, and the presence or absence of heart disease. A total of 586 medical records of dogs treated with SCDR-UFRRJ were retrospectively evaluated. Of these, 15.4% had arrhythmias, 95.6% had diagnoses of heart disease, 61.1% (55/90) were diagnosed with mitral valve disease, and 27.8% (25/90) had dilated cardiomyopathies. The most frequent rhythm disturbances were premature ventricular complexes associated with chronic degenerative mitral valve disease or dilated cardiomyopathy. Statistical analysis confirmed the risk of a cardiac patient developing rhythm or conduction alterations (OR, 4.46; p = 0.0003). In conclusion, the pathophysiology of heart failure can lead to the development of rhythm and conduction disorders.

Com a maior expectativa de vida dos animais de estimação, diversas enfermidades inerentes a idade têm sido diagnosticadas, sendo as cardiopatias um achado frequente. Apesar das diferentes cardiopatias terem fisiopatologias distintas, diversas alterações morfológicas e hemodinâmicas podem ocorrer predispondo ao aparecimento de arritmias. A presença de arritmias pode agravar a doença cardíaca de base e predispor ao desenvolvimento de novas alterações, tornando-se importante a sua detecção para instituição de protocolos terapêuticos adequados e melhor prognóstico da doença. O presente estudo teve como objetivo determinar as arritmias mais frequentemente encontradas em cães atendidos no Serviço de Cardiologia e Doenças Respiratórias (SCDR) do Setor de Pequenos Animais do Hospital Veterinário da Universidade Federal Rural do Rio de Janeiro (UFRRJ), no período de janeiro de 2014 a dezembro de 2017, relacionando-as com sexo, faixa etária, porte e presença ou não de cardiopatias. De maneira retrospectiva, foram avaliados 586 prontuários de cães atendidos no SCDR-UFRRJ. Destes, 15.4% apresentavam alguma arritmia e 95,6% apresentavam diagnostico de alguma cardiopatia, sendo 61.1% (55/90) diagnosticados com endocardiose de mitral e 27.8% (25/90) com cardiomiopatia dilatada. O distúrbio de ritmo mais frequente foram os complexos ventriculares prematuros associados a doença valvar degenerativa crônica de mitral ou a cardiomiopatia dilatada. Na análise estatística, o risco de um paciente cardiopata desenvolver alterações de ritmo ou de condução foi confirmado (OR: 4,46; p=0,0003). Conclui-se que a fisiopatologia da insuficiência cardíaca pode levar ao desenvolvimento de distúrbios de ritmo e também distúrbios de condução.

Prevalence and factors associated with Dirofilaria immitis infection in dogs in Sertão Paraibano, Northeast Brazil / Prevalência e fatores associados à infecção por Dirofilaria immitis em cães no Sertão Paraibano, Nordeste do Brasil

Dirofilaria immitis is a heart and large vessel parasite that mainly affects domestic dogs and has shown a re-emerging zoonosis in recent years. The objective of this study was to determine the prevalence, associated factors, and geographic areas of D. immitis in dogs in the city of Sousa, Paraíba, Northeast Brazil. A total of 320 dogs were selected and evaluated, 160 domiciled and 160 wandering, from the 32 districts of the city. Clinical examination, blood collection, and epidemiological data retrieval were performed for each animal. The sanitation conditions of the environment were visually observed at the time of evaluation. Three methods were used to investigate the morphometric diagnosis of microfilariae: capillary blood smear (ESC), peripheral blood smear (ESP), and modified Knott test. The data were subjected to univariate and multivariate statistics for the observation of risk factors and qualitative assessment of the examinations. Of the 17.5% (56/320) of animals testing positive for D. immitis, 25% (40/160) were wandering and 10% (16/160) were domiciled dogs. Positive dogs were found in 24 of the 32 neighborhoods evaluated, with Angelim and Doutor Zezé having the highest percentages of 1.56% (5/320) each. Only the categories of cardiac alterations (OR 6.231 [1,539-25,236]) and stray dogs (OR 2.463 [1,281-4,735]) demonstrated potential risk factors for infection. Of the 56 positive animals, 28 were positive in the three tests, and another 28 showed variance between methods and/or between prepared slides. No other filaridae were observed. The city of Sousa is considered to have a significant prevalence of infection by D. immitis, and forms of control and prophylaxis are required to reduce the risks of transmission to animals, as well as to humans.

Dirofilaria immitis é um parasito de coração e de grandes vasos que acomete principalmente cães domésticos, também causador de uma zoonose reemergente nos últimos anos. O objetivo deste trabalho foi determinar a prevalência, fatores associados e áreas geográficas de D. immitis em cães na cidade de Sousa, Paraíba, Nordeste do Brasil. Para isso, foram selecionados e avaliados 320 cães, sendo 160 domiciliados e 160 errantes, provenientes dos 32 bairros da cidade. Foi realizado o exame clínico, coleta de sangue e dados epidemiológicos de cada animal. O ambiente foi observado visualmente quanto as condições de saneamento no momento de avaliação. Para pesquisa de microfilárias, foram realizados três métodos: esfregaço sanguíneo capilar (ESC), periférico (ESP) e teste de Knott-modificado, associado ao diagnóstico morfométrico das microfilárias. Os dados foram submetidos a estatísticas uni e multivariadas para observação de fatores de risco e avaliação qualitativa dos exames. Obteve-se prevalência de 17,5% (56/320) de animais positivos para D. immitis, sendo 25% (40/160) errantes e 10% (16/160) domiciliados. Dos 32 bairros avaliados, em 24 foram encontrados cães positivos, sendo Angelim e Doutor Zezé, os bairros com maior percentual 1,56% (5/320) cada. Somente as categorias de alterações cardíacas (OR 6,231 [1.539-25.236]) e cães errantes (OR 2,463 [1.281-4.735]) demonstraram potencial fator de risco para infecção. Dos 56 animais positivos, 28 apresentaram positividade nos três testes, e outros 28 demonstraram variância entre métodos e/ou entre lâminas confeccionadas. Não foram observados outros filarídeos. Considerou-se que a cidade de Sousa apresenta prevalência significativa de infecção por D. immitis, sendo necessário estabelecer formas de controle e profilaxia, para reduzir os riscos da transmissão para animais, como também para humanos.

Electrocardiographic evaluation of baby opossum (Didelphis albiventris) / Avaliação eletrocardiográfica de gambás bebê (Didelphis albiventris)

O eletrocardiograma (ECG) é um importante método diagnóstico, essencial para determinar o ritmo e o funcionamento elétrico do coração. Os gambás (D. albiventris) frequentemente são atendidos nos Centros de Triagem de Animais Silvestres (CETAS), contudo pouco se sabe sobre o sistema cardiovascular dessa espécie. Dessa forma, o objetivo foi estabelecer valores de referência dos parâmetros eletrocardiográficos dessa espécie. Foram utilizados 32 filhotes, considerados hígidos nos exames clínicos geral e específico. Avaliaram-se a frequência cardíaca, o ritmo, a morfologia, a amplitude e a duração das ondas P, o complexo QRS e T, a duração dos intervalos PR e QT e o segmento ST. A frequência cardíaca média foi de 214 batimentos por minuto (bpm), o ritmo sinusal mostrou-se normal e houve arritmia sinusal em 25% dos pacientes. O eixo médio foi de 40º(QRS)e 47º (P). A onda P apresentou morfologia positiva (81,3%) e negativa (18,7%), amplitude de 0,03mV (±0,01) e duração de 0,04s (±0,04). O complexo QRS apresentou morfologia QRS ou RS (31%) e duração de 0,05s (±0,06). A amplitude de Q foi de -0,04mV (±0,05), a de R foi 0,23mV (±0,16) e S -0,07mV (±0,08). Já a onda T apresentou morfologia variada, amplitude de 0,04mV (±0,04) e duração de 0,04s (±0,09). O intervalo PR obteve duração de 0,05s (±0,08), QT com intervalo entre 0,08 e 0,21 e o segmento ST médio de 0,05s (±0,02). Dessa forma, observou-se que foi possível realizar o ECG em gambás filhotes e que o sexo e o peso não influenciaram no traçado obtido. Os resultados diferiram de cães, gatos e de outras espécies de gambás.

Electrocardiographic findings in dogs with obstructive airway diseases / Achados eletrocardiográficos em cães com doenças obstrutivas das vias aéreas

Cardiac rhythm disorders are diagnosed through electrocardiography, which is an important tool to investigate other systemic conditions that may be related to the cardiac conduction system. Cardiac regulation is controlled by the autonomic nervous system, and in dogs, it is mainly modulated by a parasympathetic action exerted by the vagus nerve, called vagal tone. Increased vagal tone can occur physiologically or pathologically, leading to the occurrence of bradyarrhythmias. However, some studies report that airway diseases can exacerbate this tone, together with the reduction of sympathetic pathway activities. This study aimed to analyze the cardiac rhythms in dogs presenting with electrocardiographic alterations related to respiratory diseases, in connection with the exacerbation of vagal tone. Medical records of animals whose diagnoses involved at least one respiratory condition and who underwent electrocardiographic assessment between March 2017 to March 2021 were compiled. Data obtained were compiled in Microsoft Excel®1 spreadsheets and evaluated using descriptive statistics through the BioEstat®2 software. Pearson's correlation was used for quantitative data. A correlation between autonomic regulation and vagal exacerbation was observed in cases with obstructive airways diseases.(AU)

Os distúrbios do ritmo cardíaco são diagnosticados por meio da eletrocardiografia, que é uma importante ferra-menta para investigar outras condições sistêmicas que podem estar relacionadas ao sistema de condução cardíaco. A regulação cardíaca é controlada pelo sistema nervoso autônomo e, em cães, é modulada principalmente pela ação parassimpática exer-cida pelo nervo vago, denominada tônus vagal. O aumento do tônus vagal pode ocorrer fisiologicamente ou patologicamente, levando à ocorrência de bradiarritmias. No entanto, alguns estudos relatam que as doenças das vias aéreas podem exacerbar esse tônus, juntamente com a redução das atividades das vias simpáticas. Este estudo teve como objetivo analisar os ritmos cardíacos em cães com alterações eletrocardiográficas relacionadas a doenças respiratórias, relacionadas à exacerbação do tônus vagal. Foram compilados os prontuários dos animais cujos diagnósticos envolvessem pelo menos uma condição respiratória e que realizaram avaliação eletrocardiográfica, no período entre março de 2017 a março de 2021. Os dados obtidos foram com-pilados em planilhas do Microsoft Excel®1 e avaliados por meio de estatística descritiva por meio do software BioEstat®2. A correlação de Pearson foi usada para dados quantitativos. Foi observada correlação entre regulação autonômica e exacerbação vagal em casos com doenças obstrutivas das vias aéreas.(AU)

Diagnostic accuracy of the electrocardiogram for detection of atrial and ventricular overloads in dogs

Background: Analysis of the electrocardiogram may suggest atrial and ventricular overloads. However, it has a lowsensitivity and specificity for diagnosis of cardiac chamber overload. The accuracy of electrocardiographic interpretation can be improve using new cut-offs for the duration and amplitude of the electrocardiographic waves. Ourobjective was to evaluate the use of the electrocardiogram in the diagnosis of atrial and ventricular overload, usingechocardiography as the gold standard test for the diagnosis of atrioventricular overload. We aimed to define newcut-off values that would increase the sensitivity and specificity of the electrocardiogram for diagnosis of chamberoverload in dogs.Materials, Methods & Results: Eletrocardiogram records were obtained in 81 dogs divided into 3 groups: Group1A (healthy dogs ≤ 10 kg); Group 1B (dogs ≤ 10 kg with mitral or tricuspid valve disease); Group 2 (dogs weighingbetween 10.1 and 20 kg) and Group 3 (dogs > 20.1 kg). Duration in milliseconds (ms) and amplitude in millivolts(mV) of P waves and QRS complexes, PR and QT segment, T wave amplitude and ST segment were evaluated in leadDII. Using leads I and III, the mean cardiac electrical axis in the frontal plane, expressed in degrees, was determinedas the mean of three consecutive measurements. Values considered normal in Group 1A and 1B for the durantion ofP wave was ≤ 45 ms and QRS duration ≤ 55 ms. In Group 2 the duration of P wave was ≤ 47 ms and QRS duration ≤61 ms. In Group 3 the duration of P wave was ≤ 50 ms and duration QRS ≤ 64 ms. These values (duration of P waveand QRS duration) were compared with echocardiographic measurements of the left atrium, considering the referencevalue AE/Ao ≤ 1.4 and measurements of the left ventricle in M-mode according to the body weight, respectively. AP wave amplitude ≤ 0.4 mV suggested that the right atrium size was normal and this was...

Diagnostic accuracy of the electrocardiogram for detection of atrial and ventricular overloads in dogs

Background: Analysis of the electrocardiogram may suggest atrial and ventricular overloads. However, it has a lowsensitivity and specificity for diagnosis of cardiac chamber overload. The accuracy of electrocardiographic interpretation can be improve using new cut-offs for the duration and amplitude of the electrocardiographic waves. Ourobjective was to evaluate the use of the electrocardiogram in the diagnosis of atrial and ventricular overload, usingechocardiography as the gold standard test for the diagnosis of atrioventricular overload. We aimed to define newcut-off values that would increase the sensitivity and specificity of the electrocardiogram for diagnosis of chamberoverload in dogs.Materials, Methods & Results: Eletrocardiogram records were obtained in 81 dogs divided into 3 groups: Group1A (healthy dogs ≤ 10 kg); Group 1B (dogs ≤ 10 kg with mitral or tricuspid valve disease); Group 2 (dogs weighingbetween 10.1 and 20 kg) and Group 3 (dogs > 20.1 kg). Duration in milliseconds (ms) and amplitude in millivolts(mV) of P waves and QRS complexes, PR and QT segment, T wave amplitude and ST segment were evaluated in leadDII. Using leads I and III, the mean cardiac electrical axis in the frontal plane, expressed in degrees, was determinedas the mean of three consecutive measurements. Values considered normal in Group 1A and 1B for the durantion ofP wave was ≤ 45 ms and QRS duration ≤ 55 ms. In Group 2 the duration of P wave was ≤ 47 ms and QRS duration ≤61 ms. In Group 3 the duration of P wave was ≤ 50 ms and duration QRS ≤ 64 ms. These values (duration of P waveand QRS duration) were compared with echocardiographic measurements of the left atrium, considering the referencevalue AE/Ao ≤ 1.4 and measurements of the left ventricle in M-mode according to the body weight, respectively. AP wave amplitude ≤ 0.4 mV suggested that the right atrium size was normal and this was...(AU)

Cardioprotection stimulated by resveratrol and grape products prevents lethal cardiac arrhythmias in an animal model of ischemia and reperfusion

Purpose: To evaluate the preventive cardioprotective effects of resveratrol and grape products, such as grape juice and red wine, in animal model of cardiac ischemia and reperfusion. Methods: Male Wistar rats orally pretreated for 21-days with resveratrol and grape products were anesthetized and placed on mechanical ventilation to surgically induce cardiac ischemia and reperfusion by obstruction (ischemia) followed by liberation (reperfusion) of blood circulation in left descending coronary artery. These rats were submitted to the electrocardiogram (ECG) analysis to evaluate the effects of pretreatment with resveratrol and grape products on the incidence of ventricular arrhythmias (VA), atrioventricular block (AVB) and lethality (LET) resulting from cardiac ischemia and reperfusion. Results: It was observed that the incidence of AVB was significantly lower in rats pretreated with resveratrol (25%), grape juice (37.5%) or red wine (12.5%) than in rats treated with saline solution (80%) or ethanol (80%). Similarly, incidence of LET was also significantly lower in rats pretreated with resveratrol (25%), grape juice (25%) or red wine (0%) than in rats treated with saline solution (62.5%) or ethanol (75%). Conclusion: These results indicate that the cardioprotective response stimulated by resveratrol and grape products prevents the lethal cardiac arrhythmias in animal model of ischemia and reperfusion, supporting the idea that this treatment can be beneficial for prevention of severe cardiac arrhythmias in patients with ischemic heart disease.(AU)

Estudo retrospectivo dos achados cardiorrespiratórios e laboratoriais de cães atendidos para avaliação pré-operatória em um serviço de cardiologia e doenças respiratórias (2017-2021) / Retrospective study of cardiorespiratory and laboratory findings in dogs treated for preoperative evaluation in a cardiology and respiratory disease service (2017-2021)

Os cães idosos são acometidos com frequência por enfermidades no sistema cardiovascular e respiratório, estando muita das vezes assintomáticos até terem indicação para algum procedimento cirúrgico que requer a avaliação pré-operatória, momento este que muitos achados clínicos poderão ser detectados, ao ponto da necessidade de tratamento prévio à intervenção cirúrgica. Diante disso, o trabalho tem por objetivo detectar as principais manifestações cardiorrespiratórias e sua correlação aos dados encontrados nos exames complementares e informações epidemiológicas de 138 cães atendidos em um serviço especializado em cardiologia e doenças respiratórias, no período de 2017 a 2021, para fins de risco cirúrgico. Foi possível observar maior predominância de animais idosos, de pequeno porte e do sexo feminino. Dentre as doenças cardíacas, a doença degenerativa crônica de mitral foi a mais prevalente, seguida da dirofilariose. Em relação as afecções respiratórias, a bronquite crônica e o colapso de traqueia foram mais diagnosticadas, seguidas da broncopneumonia e da síndrome braquicefálica. Quando da observação do ritmo cardíaco por meio do eletrocardiograma, a arritmia sinusal, ritmo sinusal e sinus arrest foram os principais achados. Quanto aos achados laboratoriais, foi possível observar aumento da média de hematimetria, redução da média do hematócrito e das plaquetas. Entretanto, alguns animais apresentaram azotemia, leucocitose e eosinofilia. Observou-se que pacientes com doenças cardíacas em estágios de congestão possuem redução da pressão arterial, aumento da hematimetria e taquiarritmias, como taquicardia sinusal e/ou complexos atriais prematuros. Pacientes com idade mais avançada tendem a ter redução dos valores de leucometria global e maior probabilidade de manifestação de aumento da pressão arterial. Portadores de dirofilariose cursam com aumento de eosinófilos.

Elderly dogs are frequently affected by diseases in the cardiovascular and respiratory system, being often asymptomatic until they are indicated for a surgical procedure that requires preoperative evaluation, at which point many clinical findings can be detected, to the point of need for treatment prior to surgical intervention. Therefore, the work aims to detect the main cardiorespiratory manifestations and their correlation to data found in complementary exams and demographic information of 138 animals treated at a service specialized in cardiology and respiratory diseases, from 2017 to 2021, for risk purposes surgical. It was possible to observe a greater predominance of elderly, small and female animals. Among heart diseases, chronic degenerative mitral disease was the most prevalent, followed by heartworm disease. Regarding respiratory affections, chronic bronchitis and tracheal collapse were more commonly diagnosed, followed by bronchopneumonia and brachycephalic syndrome. When observing the cardiac rhythm through the electrocardiogram, sinus arrhythmia, sinus rhythm and sinus arrest were the main findings. As for laboratory findings, it was possible to observe an increase in mean hematimetry, a reduction in mean hematocrit and platelets. However, some animals showed azotemia, leukocytosis and eosinophilia. It was observed that patients with cardiac diseases in stages of congestion have reduced blood pressure, increased hematimetry and tachyarrhythmias, such as sinus tachycardia and/or premature atrial complexes. Older patients tend to have reduced global white blood cell values and more likely to manifest increased blood pressure. Heartworm patients have an increase in eosinophils.

Eletrocardiografia computadorizada em cadelas com tumores mamários / Electrocardiography in bitches with mammary tumors

The incidence of cancer has increased due to greater longevity of the animals as a consequence of better control of other diseases, improvement of nutrition and good practices in preventive medicine. Malignant tumors can cause paraneoplastic syndrome such as hypercalcemia, anemia, cachexia, among others and consequent cardiovascular disorders. The electrocardiography (ECG) is a complementary exam that can reveal with its traces these rhythmic disorders. Based on that, the objective of this study was to evaluate the ECG in bitches with mammary tumors in order to detect in which type of tumor would be found significant changes as in cardiac rhythm, ECG waves, segments or cardiac axis. Twenty-nine female dogs were used in this study, being 19 bitches with mammary tumor, and they were allocated in three groups: G1: control group (n = 10), G2: benign neoplasia group (n = 6) and G3: malignant neoplasia group (n = 13). The most prevalent type of neoplasia in G2 was the benign mixed tumor (83%), followed by adenoma (17%) whereas in G3: carcinoma in mixed tumor (61%); papillary carcinoma (23%). Regarding cardiac rhythm, it was found sinus arrhythmia (SA) and normal sinus rhythm (NS): G1: 50% SA and 50% NS; G2: 67% SA and 33% NS; G3: 54% SA and 46% NS. No ventricular or atrial arrhythmias were detected. For other parameters in G1, G2 and G3, respectively (mean ± Std error): FC (bpm): 110±9.2, 120 ± 8.5, 124±7,5; P (ms): 48 ± 1.6, 51 ± 1.8, 50 ± 1.2; P (mV) 0.19 ± 0.02, 0.2 ± 0.02, 0.19 ± 0.02; PR (ms): 94 ± 4.3, 93 ± 5.5, 89 ± 3.9; QRS (ms): 56 ± 1.54, 60 ± 4, 62 ± 1.2; R (mV): 1.1 ± 0.06, 1.2 ± 0.24, 0.9 ± 0.13; QT (ms): 203 ± 9.4; 204 ± 7.9; 182 ± 15.6; and cardiac axis (°): 66 ± 6.2, 61 ± 7.9, 70 ± 7.5. There were no significant differences for all cardiac parameters and also for ST interval and T wave morphology. All electrocardiographic parameters found are in accordance with other studies carried out in the canine species. The results regarding tumor types differ from what was found in another study, in which in 18 bitches with mammary tumors, 55% were benign, with prevalence of adenomas (38%) followed by benign mixed tumors, and 45% malignant, with adenocarcinoma prevailing (22%). In another study, it was verified in 63 bitches the predominance of tubular carcinoma (26.56%) and carcinoma in mixed tumors (23.44%). Diverging from the electrocardiographic parameters of this study, a significant difference was found in the R wave amplitude value in the research by Barros et al., (2015) who performed computerized electrocardiography in 50 dogs, not only with mammary neoplasms (55% mammary carcinomas), but also in mastocytomas, lymphomas, benign tumors and other sarcomas. This author found out that the R wave amplitude values of the neoplasia group were lower when compared to the control group. In addition, we suspect that other types of tumors could result in more paraneoplastic syndrome than the mammary neoplasms found in this research. Neoplasms as lymphomas (T cells), apocrine gland anal sac adenocarcinomas, multiple myelomas and thymomas are known as a cause of hypercalcemia of malignancy and histiocytic sarcomas, myelomas, leukemia and lymphomas causing anemia. In conclusion, ECG has no changes in benign or malignant mammary tumors in dogs. However, this fact does not exclude the importance of its performance in pre-anesthetic evaluations. Further studies with a larger sample including the clinical staging of these bitches with a balanced number of animals with low and high staging are suggested.(AU)

Monitorização eletrocardiográfica contínua em cães portadores de degeneração mixomatosa valvular mitral / Continuous electrocardiographic monitoring in dogs with mitral valve mixomatic degeneration

A Degeneração Mixomatosa Valvar (DMV) representa um processo degenerativo crônico dos folhetos atrioventriculares, impedindo sua perfeita coaptação. Consequentemente podem ocorrem a ativação de mecanismos compensatórios congestivos e o início de uma importante sintomatologia. Em muitos casos esta enfermidade correlaciona-se com a ocorrência de importantes arritmias. Neste trabalho descrevem-se sob os aspectos clínicos e arritmogênicos, por meio do método Holter, de dois casos de DMV em pacientes de diferentes classificações funcional, segundo os critérios do Colégio Americano de Medicina Veterinária Interna, um em estágio B1 e outro em estágio D crônico. Os achados apontam que as arritmias cardíacas são eventos recorrentes em pacientes portadores de Degeneração Mixomatosa Valvar Mitral (DMVM), e que ainda em estágios iniciais, sem remodelamento, esta pode estar presente em baixa densidade; bem como nos estágios avançados, o índice de remodelamento cardíaco pode estar diretamente correlacionado à incidência de arritmias, comumente descritas na literatura, ou outras mais graves não relatadas, como a disfunção sinusal.

Myxomatous Valve Degeneration (DMV) represents a chronic degenerative process of the atrioventricular leaflets, preventing their perfect coaptation. Consequently, the activation of congestive compensatory mechanisms and the beginning of an important symptomatology may occur. In many cases this disease is correlated with the occurrence of important arrhythmias. In this work, two clinical cases of DMV in patients with different functional classification according to the American College of Internal Veterinary Medicine criteria are described under clinical and arrhythmogenic aspects, one in stage B1 and the other in chronic stage D. The findings indicate that cardiac arrhythmias are recurrent events in patients with Myxomatous Mitral Valve Degeneration (DMVM), and that even in the early stages without remodeling, they may be present in low density; as well as in the advanced stages, the cardiac remodeling index it may be directly correlated with the incidence of arrhythmias commonly described in the literature, or other more serious ones not reported, such as sinus dysfunction.

Monitorização eletrocardiográfica contínua em cães portadores de degeneração mixomatosa valvular mitral / Continuous electrocardiographic monitoring in dogs with mitral valve mixomatic degeneration

A Degeneração Mixomatosa Valvar (DMV) representa um processo degenerativo crônico dos folhetos atrioventriculares, impedindo sua perfeita coaptação. Consequentemente podem ocorrem a ativação de mecanismos compensatórios congestivos e o início de uma importante sintomatologia. Em muitos casos esta enfermidade correlaciona-se com a ocorrência de importantes arritmias. Neste trabalho descrevem-se sob os aspectos clínicos e arritmogênicos, por meio do método Holter, de dois casos de DMV em pacientes de diferentes classificações funcional, segundo os critérios do Colégio Americano de Medicina Veterinária Interna, um em estágio B1 e outro em estágio D crônico. Os achados apontam que as arritmias cardíacas são eventos recorrentes em pacientes portadores de Degeneração Mixomatosa Valvar Mitral (DMVM), e que ainda em estágios iniciais, sem remodelamento, esta pode estar presente em baixa densidade; bem como nos estágios avançados, o índice de remodelamento cardíaco pode estar diretamente correlacionado à incidência de arritmias, comumente descritas na literatura, ou outras mais graves não relatadas, como a disfunção sinusal.(AU)

Myxomatous Valve Degeneration (DMV) represents a chronic degenerative process of the atrioventricular leaflets, preventing their perfect coaptation. Consequently, the activation of congestive compensatory mechanisms and the beginning of an important symptomatology may occur. In many cases this disease is correlated with the occurrence of important arrhythmias. In this work, two clinical cases of DMV in patients with different functional classification according to the American College of Internal Veterinary Medicine criteria are described under clinical and arrhythmogenic aspects, one in stage B1 and the other in chronic stage D. The findings indicate that cardiac arrhythmias are recurrent events in patients with Myxomatous Mitral Valve Degeneration (DMVM), and that even in the early stages without remodeling, they may be present in low density; as well as in the advanced stages, the cardiac remodeling index it may be directly correlated with the incidence of arrhythmias commonly described in the literature, or other more serious ones not reported, such as sinus dysfunction.(AU)

Electrocardiographic markers of myocardial conduction and repolarization in Boxer dogs / Marcadores eletrocardiográficos de condução e repolarização miocárdica em cães da raça Boxer

ABSTRACT: Electrocardiographic markers have been used in people to classify arrhythmogenic risk. The aims of this study were to investigate electrocardiographic markers of conduction and repolarization in Boxers and non-Boxer dogs, and compare such findings between groups. Ten-lead standard electrocardiograms of Boxer dogs and non-Boxers recorded from 2015 to 2018 were retrospectively reviewed. Dogs >/ 4 years of age and weighing > 20kg were included. Animals with valvular insufficiencies, congenital cardiopathies, cardiac dilation, suspected systolic dysfunction, biphasic T-wave, bundle branch blocks, and those receiving antiarrhythmics were excluded. Electrocardiographic markers of conduction, QRS duration (QRSd) and dispersion (QRSD), and repolarization (corrected QT interval, Tpeak-Tend, JT and JTpeak), as well as derived indices, were measured. Two hundred dogs met the inclusion/exclusion requirements, including 97 Boxers (8.1±2.5 years old; 30±7kg) and 103 non-Boxer (8.8±2.5 years old, 30±8kg). QRSd and QRSD, and repolarization markers in lead II and left precordial lead V4 were considered similar between groups. Dispersion of late repolarization on lead rV2, Tpeak-Tend interval, was considered longer in Boxers (45±8ms vs 38±10ms, P=0.01). The Tpeak-Tend/JTpeak and the JTpeak/JT also differed between groups. Our results indicate that the dispersion of myocardial late repolarization in lead rV2 is slower in Boxers than other dog breeds.(AU)

Marcadores eletrocardiográficos têm sido estudados em seres humanos para estratificação do risco arritmogênico. Os objetivos deste estudo foram investigar os marcadores eletrocardiográficos de condução e repolarização miocárdica em Boxers e em cães de outras raças, e comparar tais resultados entre os grupos. Para tal, a eletrocardiografia convencional de 10 derivações registradas de 2015 a 2018 foram avaliadas de maneira retrospectiva. Cães com idade igual ou superior a 4 anos e pesando > 20kg foram incluídos. Animais com insuficiência valvar, cardiopatias congênitas, dilatação cardíaca, suspeita de disfunção sistólica, onda T bifásica, bloqueio(s) de ramo(s), ou aqueles que recebiam antiarrítmicos foram excluídos. Variáveis eletrocardiográficas de condução, como a duração e dispersão do complexo QRS (QRSd e QRSD, respectivamente), e repolarização (intervalo QT corrigido, Tpico-Tfinal, JT e JTpico), bem como índices derivados, foram mensurados. Duzentos cães que se adequaram aos critérios de inclusão/exclusão foram incluídos, 97 Boxers (8,1±2,5 anos; 30±7kg) e 103 não Boxers (8,8±2,5 anos; 30±8kg). O QRSd e o QRSD, e os marcadores de repolarização nas derivações II e V4 foram similares entre os grupos. O marcador de dispersão da repolarização tardia na derivação rV2, Tpico-Tfinal, foi considerado mais longo no Boxers (45±8ms vs 38±10ms, P=0.01). O Tpico-Tfinal/JTpico e o JTpico/JT também diferiram entre os grupos. Nossos resultados indicam que a dispersão da repolarização miocárdica tardia na derivação precordial direita, rV2, é mais lenta no Boxer do que nas outras raças.(AU)

Electrocardiographic markers of myocardial conduction and repolarization in Boxer dogs / Marcadores eletrocardiográficos de condução e repolarização miocárdica em cães da raça Boxer

Electrocardiographic markers have been used in people to classify arrhythmogenic risk. The aims of this study were to investigate electrocardiographic markers of conduction and repolarization in Boxers and non-Boxer dogs, and compare such findings between groups. Ten-lead standard electrocardiograms of Boxer dogs and non-Boxers recorded from 2015 to 2018 were retrospectively reviewed. Dogs >/ 4 years of age and weighing > 20kg were included. Animals with valvular insufficiencies, congenital cardiopathies, cardiac dilation, suspected systolic dysfunction, biphasic T-wave, bundle branch blocks, and those receiving antiarrhythmics were excluded. Electrocardiographic markers of conduction, QRS duration (QRSd) and dispersion (QRSD), and repolarization (corrected QT interval, Tpeak-Tend, JT and JTpeak), as well as derived indices, were measured. Two hundred dogs met the inclusion/exclusion requirements, including 97 Boxers (8.1±2.5 years old; 30±7kg) and 103 non-Boxer (8.8±2.5 years old, 30±8kg). QRSd and QRSD, and repolarization markers in lead II and left precordial lead V4 were considered similar between groups. Dispersion of late repolarization on lead rV2, Tpeak-Tend interval, was considered longer in Boxers (45±8ms vs 38±10ms, P=0.01). The Tpeak-Tend/JTpeak and the JTpeak/JT also differed between groups. Our results indicate that the dispersion of myocardial late repolarization in lead rV2 is slower in Boxers than other dog breeds.(AU)

Marcadores eletrocardiográficos têm sido estudados em seres humanos para estratificação do risco arritmogênico. Os objetivos deste estudo foram investigar os marcadores eletrocardiográficos de condução e repolarização miocárdica em Boxers e em cães de outras raças, e comparar tais resultados entre os grupos. Para tal, a eletrocardiografia convencional de 10 derivações registradas de 2015 a 2018 foram avaliadas de maneira retrospectiva. Cães com idade igual ou superior a 4 anos e pesando > 20kg foram incluídos. Animais com insuficiência valvar, cardiopatias congênitas, dilatação cardíaca, suspeita de disfunção sistólica, onda T bifásica, bloqueio(s) de ramo(s), ou aqueles que recebiam antiarrítmicos foram excluídos. Variáveis eletrocardiográficas de condução, como a duração e dispersão do complexo QRS (QRSd e QRSD, respectivamente), e repolarização (intervalo QT corrigido, Tpico-Tfinal, JT e JTpico), bem como índices derivados, foram mensurados. Duzentos cães que se adequaram aos critérios de inclusão/exclusão foram incluídos, 97 Boxers (8,1±2,5 anos; 30±7kg) e 103 não Boxers (8,8±2,5 anos; 30±8kg). O QRSd e o QRSD, e os marcadores de repolarização nas derivações II e V4 foram similares entre os grupos. O marcador de dispersão da repolarização tardia na derivação rV2, Tpico-Tfinal, foi considerado mais longo no Boxers (45±8ms vs 38±10ms, P=0.01). O Tpico-Tfinal/JTpico e o JTpico/JT também diferiram entre os grupos. Nossos resultados indicam que a dispersão da repolarização miocárdica tardia na derivação precordial direita, rV2, é mais lenta no Boxer do que nas outras raças.(AU)

Prevalence study of arrhythmia in dogs affected for mitral valve disease / Estudo da prevalência de arritmias em cães afetados por doença valvar mitral

The mitral valve disease is considered more common heart disease between dogs, and occurs mostly in geriatric and small size dogs. The most affected breeds are, Poodle, Pinscher, Yorkshire Terrier, Fox Terrier, among others. The general signs related to heart disease are cough, tachypnea and lethargy. Another common disorder is arrhythmia, basically related to origin or conduction alterations of electric impulses. Both disorders can be associated in the same patient, which makes necessary the realization of complementary tests for earlier diagnosis and placement of appropriate therapy for the dog, such as, chest radiography, electrocardiogram and echocardiogram. The aim of this paper was to observe, by means of cases retrospective study, the relationship between mitral valve disease and different cardiac rhythms. It was possible observe that alterations in cardiac rhythms are closely linked with activating of neurohormonal compensatory mechanisms of organism due to cardiac remodeling caused for mitral valve disease.

A doença valvar mitral é considerada a cardiopatia mais comum entre cães, e acomete em grande parte cães idosos e de pequeno porte. As raças mais afetadas são Poodle, Pinscher, Yorkshire terrier, Fox terrier, dentre outras. Os principais sinais relacionados à cardiopatia são tosse, taquipneia e letargia. Outro distúrbio comum é a arritmia, basicamente relacionada a alterações na origem ou condução de impulsos elétricos. Ambos os distúrbios podem estar associados no mesmo paciente, o que torna necessário a realização de exames complementares para o diagnóstico precoce e instituição de terapia apropriada para o cão, tais como a radiografia torácica, eletrocardiograma e ecocardiograma. O objetivo deste estudo foi observar, por meio de estudo retrospectivo de casos, a relação entre doença valvar mitral e diferentes ritmos cardíacos. Foi possível observar que alterações nos ritmos cardíacos estão intimamente relacionados à ativação de mecanismos compensatórios neurohormonais do organismo, devido ao remodelamento cardíaco causado por doença valvar mitral.

Prevalence study of arrhythmia in dogs affected for mitral valve disease / Estudo da prevalência de arritmias em cães afetados por doença valvar mitral

The mitral valve disease is considered more common heart disease between dogs, and occurs mostly in geriatric and small size dogs. The most affected breeds are, Poodle, Pinscher, Yorkshire Terrier, Fox Terrier, among others. The general signs related to heart disease are cough, tachypnea and lethargy. Another common disorder is arrhythmia, basically related to origin or conduction alterations of electric impulses. Both disorders can be associated in the same patient, which makes necessary the realization of complementary tests for earlier diagnosis and placement of appropriate therapy for the dog, such as, chest radiography, electrocardiogram and echocardiogram. The aim of this paper was to observe, by means of cases retrospective study, the relationship between mitral valve disease and different cardiac rhythms. It was possible observe that alterations in cardiac rhythms are closely linked with activating of neurohormonal compensatory mechanisms of organism due to cardiac remodeling caused for mitral valve disease.(AU)

A doença valvar mitral é considerada a cardiopatia mais comum entre cães, e acomete em grande parte cães idosos e de pequeno porte. As raças mais afetadas são Poodle, Pinscher, Yorkshire terrier, Fox terrier, dentre outras. Os principais sinais relacionados à cardiopatia são tosse, taquipneia e letargia. Outro distúrbio comum é a arritmia, basicamente relacionada a alterações na origem ou condução de impulsos elétricos. Ambos os distúrbios podem estar associados no mesmo paciente, o que torna necessário a realização de exames complementares para o diagnóstico precoce e instituição de terapia apropriada para o cão, tais como a radiografia torácica, eletrocardiograma e ecocardiograma. O objetivo deste estudo foi observar, por meio de estudo retrospectivo de casos, a relação entre doença valvar mitral e diferentes ritmos cardíacos. Foi possível observar que alterações nos ritmos cardíacos estão intimamente relacionados à ativação de mecanismos compensatórios neurohormonais do organismo, devido ao remodelamento cardíaco causado por doença valvar mitral.(AU)

Arritmias no uso da dexmedetomina em cães / Arrhythmias in the use of dexmedethine in dogs

A dexmedetomidina é um fármaco agonista a-2 adrenérgico utilizado na anestesiologia veterinária, devido a suas propriedades sedativas e analgésicas. Existem preocupações quanto aos seus efeitos colaterais, principalmente cardiovasculares, dentre eles arritmias. As quais podem comprometer o débito cardíaco e a perfusão tecidual. As arritmias que podem ser observadas com o uso da dexmedetomidina são: bloqueio átrio ventricular de 1º, 2º e 3º grau; arritmia sinusal, e pausa sinusal. Dentre elas a de maior ocorrência é o bloqueio atrioventricular, principalmente o de 2º grau. Essas alterações são dose-dependentes, estudos demonstram que doses de 1 µg /kg podem desencadear a ocorrência de bradiarritmias. O tratamento das arritmias atrioventriculares envolve a administração de anticolinérgicos, antiarrítmicos e no caso de alterações desencadeadas pelo uso da dexmedetomidina a aplicação de um antagonista a-2 adrenérgico. Esta revisão tem como objetivo discorrer sobre as arritmias em cães ocasionadas pelo uso da dexmedetomidina.

Dexmedetomidine is a α-2 adrenergic agonist drug used in veterinary anesthesiologydue to its sedative and analgesic properties. There are concerns about its side effects, especially cardiovascular, among them arrhythmias. These may compromise cardiac output and tissue perfusion. The arrhythmias that may be observed with the use of dexmedetomidine are: ventricularatrium blockade of 1st, 2nd and 3rd degree; sinus arrhythmia, and sinus pause. Among them, the most frequent occurrence is atrioventricular block, especially the second degree. These changes are dose-dependent, studies have shown that doses of 1 μg/kg can trigger the occurrence of bradyarrhythmias. Treatment of atrioventricular arrhythmias involves the administration of anticholinergics, antiarrhythmics and in the case of changes triggered by the use of dexmedetomidinethe application of a α-2 adrenergic antagonist. This review aims to discuss the arrhythmias in dogs caused by the use of dexmedetomidine.

Arritmias no uso da dexmedetomina em cães / Arrhythmias in the use of dexmedethine in dogs

A dexmedetomidina é um fármaco agonista a-2 adrenérgico utilizado na anestesiologia veterinária, devido a suas propriedades sedativas e analgésicas. Existem preocupações quanto aos seus efeitos colaterais, principalmente cardiovasculares, dentre eles arritmias. As quais podem comprometer o débito cardíaco e a perfusão tecidual. As arritmias que podem ser observadas com o uso da dexmedetomidina são: bloqueio átrio ventricular de 1º, 2º e 3º grau; arritmia sinusal, e pausa sinusal. Dentre elas a de maior ocorrência é o bloqueio atrioventricular, principalmente o de 2º grau. Essas alterações são dose-dependentes, estudos demonstram que doses de 1 µg /kg podem desencadear a ocorrência de bradiarritmias. O tratamento das arritmias atrioventriculares envolve a administração de anticolinérgicos, antiarrítmicos e no caso de alterações desencadeadas pelo uso da dexmedetomidina a aplicação de um antagonista a-2 adrenérgico. Esta revisão tem como objetivo discorrer sobre as arritmias em cães ocasionadas pelo uso da dexmedetomidina.(AU)

Dexmedetomidine is a α-2 adrenergic agonist drug used in veterinary anesthesiologydue to its sedative and analgesic properties. There are concerns about its side effects, especially cardiovascular, among them arrhythmias. These may compromise cardiac output and tissue perfusion. The arrhythmias that may be observed with the use of dexmedetomidine are: ventricularatrium blockade of 1st, 2nd and 3rd degree; sinus arrhythmia, and sinus pause. Among them, the most frequent occurrence is atrioventricular block, especially the second degree. These changes are dose-dependent, studies have shown that doses of 1 μg/kg can trigger the occurrence of bradyarrhythmias. Treatment of atrioventricular arrhythmias involves the administration of anticholinergics, antiarrhythmics and in the case of changes triggered by the use of dexmedetomidinethe application of a α-2 adrenergic antagonist. This review aims to discuss the arrhythmias in dogs caused by the use of dexmedetomidine.(AU)

Eletrocardiografia em cadelas submetidas à mastectomia unilateral total / Electrocardiogram in bitches submitted to unilateral total mastectomy

Background: The frequency of oncological diseases in companion animals has increased in recent years, mainly due tothe longer longevity of dogs. The neoplasms are not only open by the presence of the tumor and its location, but also byparaneoplastic syndromes, which are disorders that occur due to the production of substances by the tumor that cause.In addition to causing local changes and damages, oncological diseases may also result in injuries at distant sites, suchas paraneoplastic syndromes, which, if untreated, may result in death of animals. The present study aimed to investigatewhether female dogs with mammary tumors demonstrate electrocardiographic changes, and if so, to investigate whetherthese cease after removal of the tumor, and to relate the type of tumor with the occurrence of arrhythmias.Materials, Methods & Results: Eighteen female dogs, aged between 4 and 14 years, underwent electrocardiogram 24 hprior to undergoing a total unilateral mastectomy. After removal of the tumor, electrocardiograms were again performed 24(M24), 48 (M48), and 72 (M72), as well as 14 days (M14d) after surgery. Histological analysis of the neoplasms showedthat 55% of the tumors were benign, with predominance of adenoma (38%), and 45% were malignant, with predominanceof adenocarcinoma (22%). The following rhythms and arrhythmias were observed: normal sinus rhythm (37.2%), sinusarrhythmia (62.8%), wandering pacemaker (26%), 1st degree atrioventricular block (AVB; 5%), premature ventricularcomplex (PVC; 10%), and T-wave > 25% of R-wave (25%); more than one change could occur simultaneously. Out of theevaluated electrocardiographic parameters, a significant difference was observed in the QT interval between the followingtimepoints: M24 (204 ± 18), M48 (204 ± 22), and M72 (203 ± 23), as well as Mbasal (192 ± 15) and M14d (178 ± 43).Discussion: Regarding the observed rhythms, arrhythmias, and changes, respiratory sinus arrhythmia was the normal predominant... (AU)

Eletrocardiografia em cadelas submetidas à mastectomia unilateral total / Electrocardiogram in bitches submitted to unilateral total mastectomy

Background: The frequency of oncological diseases in companion animals has increased in recent years, mainly due tothe longer longevity of dogs. The neoplasms are not only open by the presence of the tumor and its location, but also byparaneoplastic syndromes, which are disorders that occur due to the production of substances by the tumor that cause.In addition to causing local changes and damages, oncological diseases may also result in injuries at distant sites, suchas paraneoplastic syndromes, which, if untreated, may result in death of animals. The present study aimed to investigatewhether female dogs with mammary tumors demonstrate electrocardiographic changes, and if so, to investigate whetherthese cease after removal of the tumor, and to relate the type of tumor with the occurrence of arrhythmias.Materials, Methods & Results: Eighteen female dogs, aged between 4 and 14 years, underwent electrocardiogram 24 hprior to undergoing a total unilateral mastectomy. After removal of the tumor, electrocardiograms were again performed 24(M24), 48 (M48), and 72 (M72), as well as 14 days (M14d) after surgery. Histological analysis of the neoplasms showedthat 55% of the tumors were benign, with predominance of adenoma (38%), and 45% were malignant, with predominanceof adenocarcinoma (22%). The following rhythms and arrhythmias were observed: normal sinus rhythm (37.2%), sinusarrhythmia (62.8%), wandering pacemaker (26%), 1st degree atrioventricular block (AVB; 5%), premature ventricularcomplex (PVC; 10%), and T-wave > 25% of R-wave (25%); more than one change could occur simultaneously. Out of theevaluated electrocardiographic parameters, a significant difference was observed in the QT interval between the followingtimepoints: M24 (204 ± 18), M48 (204 ± 22), and M72 (203 ± 23), as well as Mbasal (192 ± 15) and M14d (178 ± 43).Discussion: Regarding the observed rhythms, arrhythmias, and changes, respiratory sinus arrhythmia was the normal predominant...

Prognostic value of coupling interval, prematurity index and heart rate variability in Boxer dogs / Valor prognóstico do intervalo de acoplamento, índice de prematuridade e variabilidade da frequência cardíaca em cães da raça Boxer

Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC) can experience sudden cardiac death regardless of presence/absence of clinical signs. The aims of this retrospective study were two-fold: 1) to investigate the coupling interval (CI) and prematurity index (PI) of ventricular arrhythmias (VA), and the heart rate variability (HRV) in Boxers, and 2) to evaluate their impact on overall survival time. The first 24-hour Holter 36 client-owned Boxer dogs meeting inclusion/exclusion criteria were evaluated for the number, morphology, site of origin, complexity, CI and PI, of ventricular premature complexes (VPCs), and time domain HRV. The effect on survival was assessed, considering the presence/absence of ventricular tachycardia (VT), and syncope. All-cause mortality was considered as the end-point, with median survival times being obtained by Kaplan-Meier analyses and compared by log-rank test. Polymorphic VPCs were more common in symptomatic dogs than asymptomatic. VPCs in dogs with VT were less premature, due to the influence of heart rate on PI despite comparable CI. The PI and mean heart rate (HRme) were significantly different between VT and non-VT dogs but did not discriminate adequately between groups as standalone tests. Median survival time was shorter in Boxer dogs with VT (463 vs 1645 days, HR: 4.31, P=0.03). The HRV parameters, SDNN and SDANN, were both associated with prognosis. The CI and PI were not demonstrated to be prognostic surrogates in Boxer dogs with VA. HRme≥112bpm is 100% sensitive but only 46% specific for detecting VT in Boxers on the 24-hour Holter. Presence of VT, SDNN≤245ms, or SDANN≤134ms at the time of the first 24-hour Holter was associated with a shorter survival.(AU)

Cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) podem apresentar morte súbita independentemente da presença/ausência de sinais clínicos. Os objetivos desse estudo retrospectivo foram: 1) investigar o intervalo de acoplamento (IA) e o índice de prematuridade (IP) das arritmias ventriculares e a variabilidade da frequência cardíaca (VFC) em Boxers, e 2) avaliar o impacto de tais características sob o tempo de sobrevida global. O primeiro Holter de 24 horas de 36 Boxers selecionados para os critérios de inclusão/exclusão foram avaliados para o número, morfologia, local de origem, complexidade, IA e IP dos complexos ventriculares prematuros (CVPs) e da VFC no domínio do tempo. O efeito na sobrevida foi avaliado, considerado a presença/ausência de taquicardia ventricular (TV), e síncope. O desfecho final foi a mortalidade global, com o tempo de sobrevida mediano sendo obtido pela análise de Kaplan-Meier e comparado pelo teste de log-rank. CVPs polimórficos foram mais comuns em cães sintomáticos. Os CVPs em Boxers com TV foram menos prematuros, devido à influência da frequência cardíaca (FC) sobre o IP, apesar de IA comparáveis. O IP e a FC média diferiram entre os cães com TV e os sem, mas não discriminam adequadamente os grupos como variáveis isoladas. A sobrevida global foi menor nos cães com TV (463 dias vs 1645 dias, HR=4,31, P=0,03). Os parâmetros da VFC, SDNN e SDANN, foram associados ao prognóstico. O IA e o IP não possuem valor prognóstico em Boxers com arritmias ventriculares. A FC média ≥112bpm é 100% sensível, mas apenas 46% específica para detectar Boxers com TV no Holter de 24 horas. A presença de TV, SDNN≤245ms, ou SDANN≤134ms no momento do primeiro Holter de 24 horas estão associados a menor sobrevida global no Boxer.(AU)