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.

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)

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)

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)

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)

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)

Time domain heart rate variability in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy / Variabilidade da frequência cardíaca no domínio do tempo em cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito

The aim of the present study was to assess heart rate variability (HRV) in Boxer dogs affected by arrhythmogenic right ventricular cardiomyopathy (ARVC). Fourteen Boxer dogs classified as affected and 28 classified as unaffected were included in a prospective case-control study. Dogs underwent 24-hour ambulatory ECG and were classified as affected (>1,000 VPCs/24 hours) or unaffected (<20 VPCs/24 hours) by ARVC based on the number of ventricular arrhythmias. HRV was assessed using 24-h Holter ECG monitoring; the studied parameters were SDNN, SDANN, SDNNIDX, rMSSD and pNN50. Data were submitted to logarithmic transformation and HRV parameters were compared between groups and correlated according to the disease status, number and severity of ventricular arrhythmias using Student’s t test, linear regression and Spearman’s test. There was no interaction between the HRV parameters and the number and severity of ventricular arrhythmias. SDNNlog (2.35±0.14 vs. 2.46±0.12, P=0.01), SDNNIDXlog (2.18±0.14 vs. 2.24±0.10, P=0.002) and pNN50log (1.47±0.19 vs. 1.64±0.13, P=0.002) were significantly lower in the affected group compared with the unaffected. According to this study, HRV are different in a population of Boxers dogs affected by ARVC compared to a population of unaffected dogs, and these differences are not consequences of low cardiac output caused by ventricular arrhythmias since animals that had higher number and complexity of arrhythmias were not those who had lower values of HRV.

O objetivo do presente estudo foi avaliar a variabilidade da frequência cardíaca (VFC) em cães da raça Boxer acometidos pela cardiomiopatia arritmogênica do ventrículo direito (CAVD). Para isso, foram incluídos, em estudo prospectivo caso-controle, 14 cães classificados como acometidos pela CAVD e 28 classificados como não acometidos. Os cães foram submetidos à eletrocardiografia ambulatorial de 24 horas e então classificados como acometidos (quando apresentaram mais de 1.000 complexos ventriculares prematuros em 24 horas) ou não acometidos (quando apresentaram menos de 20 complexos ventriculares prematuros em 24 horas) pela CAVD, com base no número de arritmias ventriculares. A VFC foi avaliada mediante monitoramento Holter de 24 horas. Os parâmetros estudados foram SDNN, SDANN, SDNNIDX, rMSSD e pNN50. Os dados foram submetidos à transformação logarítmica e os parâmetros da VFC foram comparados e correlacionados de acordo com a presença ou não da doença, número e severidade das arritmias pelo teste t de Student, regressão linear e teste de Spearman. Não houve interação entre as variáveis da VFC e o número e a severidade das arritmias ventriculares. Porém, as variáveis SDNNlog (2,35±0,14 vs. 2,46±0,12, P=0,01), SDNNIDXlog (2,18±0,14 vs. 2,24±0,10, P=0.002) e pNN50log (1,47±0,19 vs. 1,64±0,13, P=0,002) foram significativamente menores no grupo de animais acometidos pela doença. De acordo com os resultados do presente estudo, a VFC é menor nos Boxers acometidos pela CAVD em relação aos cães não acometidos, e essa diferença não pode ser atribuída ao baixo débito cardíaco, supostamente causado pelas arritmias ventriculares, uma vez que os animais que apresentaram maior número e complexidade das arritmias não foram os que apresentaram os menores valores da VFC.

Time domain heart rate variability in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy / Variabilidade da frequência cardíaca no domínio do tempo em cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito

The aim of the present study was to assess heart rate variability (HRV) in Boxer dogs affected by arrhythmogenic right ventricular cardiomyopathy (ARVC). Fourteen Boxer dogs classified as affected and 28 classified as unaffected were included in a prospective case-control study. Dogs underwent 24-hour ambulatory ECG and were classified as affected (>1,000 VPCs/24 hours) or unaffected (<20 VPCs/24 hours) by ARVC based on the number of ventricular arrhythmias. HRV was assessed using 24-h Holter ECG monitoring; the studied parameters were SDNN, SDANN, SDNNIDX, rMSSD and pNN50. Data were submitted to logarithmic transformation and HRV parameters were compared between groups and correlated according to the disease status, number and severity of ventricular arrhythmias using Students t test, linear regression and Spearmans test. There was no interaction between the HRV parameters and the number and severity of ventricular arrhythmias. SDNNlog (2.35±0.14 vs. 2.46±0.12, P=0.01), SDNNIDXlog (2.18±0.14 vs. 2.24±0.10, P=0.002) and pNN50log (1.47±0.19 vs. 1.64±0.13, P=0.002) were significantly lower in the affected group compared with the unaffected. According to this study, HRV are different in a population of Boxers dogs affected by ARVC compared to a population of unaffected dogs, and these differences are not consequences of low cardiac output caused by ventricular arrhythmias since animals that had higher number and complexity of arrhythmias were not those who had lower values of HRV.(AU)

O objetivo do presente estudo foi avaliar a variabilidade da frequência cardíaca (VFC) em cães da raça Boxer acometidos pela cardiomiopatia arritmogênica do ventrículo direito (CAVD). Para isso, foram incluídos, em estudo prospectivo caso-controle, 14 cães classificados como acometidos pela CAVD e 28 classificados como não acometidos. Os cães foram submetidos à eletrocardiografia ambulatorial de 24 horas e então classificados como acometidos (quando apresentaram mais de 1.000 complexos ventriculares prematuros em 24 horas) ou não acometidos (quando apresentaram menos de 20 complexos ventriculares prematuros em 24 horas) pela CAVD, com base no número de arritmias ventriculares. A VFC foi avaliada mediante monitoramento Holter de 24 horas. Os parâmetros estudados foram SDNN, SDANN, SDNNIDX, rMSSD e pNN50. Os dados foram submetidos à transformação logarítmica e os parâmetros da VFC foram comparados e correlacionados de acordo com a presença ou não da doença, número e severidade das arritmias pelo teste t de Student, regressão linear e teste de Spearman. Não houve interação entre as variáveis da VFC e o número e a severidade das arritmias ventriculares. Porém, as variáveis SDNNlog (2,35±0,14 vs. 2,46±0,12, P=0,01), SDNNIDXlog (2,18±0,14 vs. 2,24±0,10, P=0.002) e pNN50log (1,47±0,19 vs. 1,64±0,13, P=0,002) foram significativamente menores no grupo de animais acometidos pela doença. De acordo com os resultados do presente estudo, a VFC é menor nos Boxers acometidos pela CAVD em relação aos cães não acometidos, e essa diferença não pode ser atribuída ao baixo débito cardíaco, supostamente causado pelas arritmias ventriculares, uma vez que os animais que apresentaram maior número e complexidade das arritmias não foram os que apresentaram os menores valores da VFC.(AU)

Time domain heart rate variability in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy

ABSTRACT: The aim of the present study was to assess heart rate variability (HRV) in Boxer dogs affected by arrhythmogenic right ventricular cardiomyopathy (ARVC). Fourteen Boxer dogs classified as affected and 28 classified as unaffected were included in a prospective case-control study. Dogs underwent 24-hour ambulatory ECG and were classified as affected (>1,000 VPCs/24 hours) or unaffected ( 20 VPCs/24 hours) by ARVC based on the number of ventricular arrhythmias. HRV was assessed using 24-h Holter ECG monitoring; the studied parameters were SDNN, SDANN, SDNNIDX, rMSSD and pNN50. Data were submitted to logarithmic transformation and HRV parameters were compared between groups and correlated according to the disease status, number and severity of ventricular arrhythmias using Students t test, linear regression and Spearmans test. There was no interaction between the HRV parameters and the number and severity of ventricular arrhythmias. SDNNlog (2.35±0.14 vs. 2.46±0.12, P=0.01), SDNNIDXlog (2.18±0.14 vs. 2.24±0.10, P=0.002) and pNN50log (1.47±0.19 vs. 1.64±0.13, P=0.002) were significantly lower in the affected group compared with the unaffected. According to this study, HRV are different in a population of Boxers dogs affected by ARVC compared to a population of unaffected dogs, and these differences are not consequences of low cardiac output caused by ventricular arrhythmias since animals that had higher number and complexity of arrhythmias were not those who had lower values of HRV.

RESUMO: O objetivo do presente estudo foi avaliar a variabilidade da frequência cardíaca (VFC) em cães da raça Boxer acometidos pela cardiomiopatia arritmogênica do ventrículo direito (CAVD). Para isso, foram incluídos, em estudo prospectivo caso-controle, 14 cães classificados como acometidos pela CAVD e 28 classificados como não acometidos. Os cães foram submetidos à eletrocardiografia ambulatorial de 24 horas e então classificados como acometidos (quando apresentaram mais de 1.000 complexos ventriculares prematuros em 24 horas) ou não acometidos (quando apresentaram menos de 20 complexos ventriculares prematuros em 24 horas) pela CAVD, com base no número de arritmias ventriculares. A VFC foi avaliada mediante monitoramento Holter de 24 horas. Os parâmetros estudados foram SDNN, SDANN, SDNNIDX, rMSSD e pNN50. Os dados foram submetidos à transformação logarítmica e os parâmetros da VFC foram comparados e correlacionados de acordo com a presença ou não da doença, número e severidade das arritmias pelo teste t de Student, regressão linear e teste de Spearman. Não houve interação entre as variáveis da VFC e o número e a severidade das arritmias ventriculares. Porém, as variáveis SDNNlog (2,35±0,14 vs. 2,46±0,12, P=0,01), SDNNIDXlog (2,18±0,14 vs. 2,24±0,10, P=0.002) e pNN50log (1,47±0,19 vs. 1,64±0,13, P=0,002) foram significativamente menores no grupo de animais acometidos pela doença. De acordo com os resultados do presente estudo, a VFC é menor nos Boxers acometidos pela CAVD em relação aos cães não acometidos, e essa diferença não pode ser atribuída ao baixo débito cardíaco, supostamente causado pelas arritmias ventriculares, uma vez que os animais que apresentaram maior número e complexidade das arritmias não foram os que apresentaram os menores valores da VFC.

Dogs poisoned with Nerium oleander fresh leaves: clinical and electrocardiographic findings / Cães intoxicados com folhas frescas de Nerium oleander: achados clínicos e eletrocardiográficos

Nerium oleander is distributed worldwide, mainly in tropical and subtropical regions. These shrubs are frequently used as ornamental plants. However, they contain more than 30 cardiac glycosides that can cause serious toxic effects in dogs. The objective of this study was to report the clinical and electrocardiographic alterations in dogs experimentally poisoned with N. oleander. Ten adult, healthy, mixed-breed dogs weighing 10-25kg and aged 3-6 years were selected for the study. We orally administered 0.25g kg-1 of fresh ground leaves of N. oleander to the dogs. No dog died after the ingestion, but all exhibited signs of poisoning such as vomiting, sialorrhea, nausea, apathy, conjunctiva congestion, dehydration, abdominal pain, tremors, diarrhea, loss of appetite, and tenesmus. Electrocardiogram revealed occurrence of several types of arrhythmias: sinus bradycardia, second-degree atrioventricular block, paroxysmal ventricular tachycardia, and ventricular premature complexes. Systolic blood pressure, as well as heart rate, decreased in the first 24 hours. The present study concluded that a single dose of 0.25g kg-1 of N. oleander green leaves is sufficient to cause a moderate intoxication in dogs, with nonspecific clinical changes mainly related to the digestive system and heart rate, thus demonstrating the importance of this type of intoxication in the list of differential diagnoses of small animals routine.

O Nerium oleander é uma planta com ampla distribuição mundial, principalmente em regiões tropicais e subtropicais. Esses arbustos são frequentemente usados como plantas ornamentais e possuem mais de 30 glicosídeos cardíacos causadores do quadro clínico de intoxicação em caninos. Sabendo-se disso, este artigo teve por objetivo a avaliar as alterações clínicas e eletrocardiográficas, nos animais intoxicados experimentalmente com N. oleander. Foram utilizados 10 cães adultos, hígidos, sem raça definida, com 10 a 25kg de peso, de 3 a 6 anos de idade. Os animais receberam uma única dose de 0,25g kg-1 de peso, de folhas frescas de N. oleander. Nenhum dos animais do experimento veio a óbito. Os sinais clínicos observados foram vômito, sialorréia, náuseas, apatia, conjuntiva ocular congesta, desidratação, dor abdominal, tremores, diarreia, inapetência e tenesmo. Pela análise do eletrocardiograma encontraram-se arritmias como: bradicardia sinusal, bloqueios atrioventriculares de segundo grau, taquicardia ventricular paroxística e complexo ventricular prematuro. A pressão arterial sistólica diminui nas primeiras 24 horas, assim como a frequência cardíaca. Concluiu-se com o presente estudo que uma única dose de 0,25g kg-1 de folhas verdes de N. oleander é suficiente para causar um quadro moderado de intoxicação em cães, com alterações clínicas inespecíficas principalmente relacionadas ao sistema digestório e no ritmo cardíaco, mostrando a importância deste tipo de intoxicação na lista de diagnósticos diferenciais da rotina de pequenos animais.

Dogs poisoned with Nerium oleander fresh leaves: clinical and electrocardiographic findings / Cães intoxicados com folhas frescas de Nerium oleander: achados clínicos e eletrocardiográficos

Nerium oleander is distributed worldwide, mainly in tropical and subtropical regions. These shrubs are frequently used as ornamental plants. However, they contain more than 30 cardiac glycosides that can cause serious toxic effects in dogs. The objective of this study was to report the clinical and electrocardiographic alterations in dogs experimentally poisoned with N. oleander. Ten adult, healthy, mixed-breed dogs weighing 10-25kg and aged 3-6 years were selected for the study. We orally administered 0.25g kg-1 of fresh ground leaves of N. oleander to the dogs. No dog died after the ingestion, but all exhibited signs of poisoning such as vomiting, sialorrhea, nausea, apathy, conjunctiva congestion, dehydration, abdominal pain, tremors, diarrhea, loss of appetite, and tenesmus. Electrocardiogram revealed occurrence of several types of arrhythmias: sinus bradycardia, second-degree atrioventricular block, paroxysmal ventricular tachycardia, and ventricular premature complexes. Systolic blood pressure, as well as heart rate, decreased in the first 24 hours. The present study concluded that a single dose of 0.25g kg-1 of N. oleander green leaves is sufficient to cause a moderate intoxication in dogs, with nonspecific clinical changes mainly related to the digestive system and heart rate, thus demonstrating the importance of this type of intoxication in the list of differential diagnoses of small animals routine.(AU)

O Nerium oleander é uma planta com ampla distribuição mundial, principalmente em regiões tropicais e subtropicais. Esses arbustos são frequentemente usados como plantas ornamentais e possuem mais de 30 glicosídeos cardíacos causadores do quadro clínico de intoxicação em caninos. Sabendo-se disso, este artigo teve por objetivo a avaliar as alterações clínicas e eletrocardiográficas, nos animais intoxicados experimentalmente com N. oleander. Foram utilizados 10 cães adultos, hígidos, sem raça definida, com 10 a 25kg de peso, de 3 a 6 anos de idade. Os animais receberam uma única dose de 0,25g kg-1 de peso, de folhas frescas de N. oleander. Nenhum dos animais do experimento veio a óbito. Os sinais clínicos observados foram vômito, sialorréia, náuseas, apatia, conjuntiva ocular congesta, desidratação, dor abdominal, tremores, diarreia, inapetência e tenesmo. Pela análise do eletrocardiograma encontraram-se arritmias como: bradicardia sinusal, bloqueios atrioventriculares de segundo grau, taquicardia ventricular paroxística e complexo ventricular prematuro. A pressão arterial sistólica diminui nas primeiras 24 horas, assim como a frequência cardíaca. Concluiu-se com o presente estudo que uma única dose de 0,25g kg-1 de folhas verdes de N. oleander é suficiente para causar um quadro moderado de intoxicação em cães, com alterações clínicas inespecíficas principalmente relacionadas ao sistema digestório e no ritmo cardíaco, mostrando a importância deste tipo de intoxicação na lista de diagnósticos diferenciais da rotina de pequenos animais.(AU)

Holter monitoring (24-h electrocardiography) of Holstein calves

Background: Twenty-four h electrocardiographic monitoring is a noninvasive method of assessing cardiac rhythm. Holter monitoring in farm animals can help assessing heart rate variability and its relationship with stress and production. Several authors have reviewed the normal cardiac rhythm of bovines, but there is little information on heart rhythm in calves. The goal of this research is to elucidate which cardiac rhythms may be considered physiological in Holstein calves, from 3 to 6 months old. Materials, Methods & Results: Twenty-four h ambulatory electrocardiography (Holter monitoring) was performed in 10 male Holstein calves, with ages ranging from 3 to 6 months old. The animals came from private farms in São Paulo state and were housed in a semi-open stall during the study. The animals had their hair clipped from the third to the fifth intercostal spaces on both sides of the chest, from the sternal region to the glenohumeral joint, and seven electrodes were positioned in a diagonal configuration. Decoding of the recordings was performed using specialized software and in order to minimize digital mistakes, all of the beats marked as ectopic by the software were manually revised by the authors. Mean heart rate was 83.2 ± 11.06 beats per min (bpm), maximum heart rate was 147.1 ± 11.05 bpm, and minimum heart rate was 53.7 ± 7.45 bpm. In 90% of the calves, normal sinus [...](AU)

Holter monitoring (24-h electrocardiography) of Holstein calves

Background: Twenty-four h electrocardiographic monitoring is a noninvasive method of assessing cardiac rhythm. Holter monitoring in farm animals can help assessing heart rate variability and its relationship with stress and production. Several authors have reviewed the normal cardiac rhythm of bovines, but there is little information on heart rhythm in calves. The goal of this research is to elucidate which cardiac rhythms may be considered physiological in Holstein calves, from 3 to 6 months old. Materials, Methods & Results: Twenty-four h ambulatory electrocardiography (Holter monitoring) was performed in 10 male Holstein calves, with ages ranging from 3 to 6 months old. The animals came from private farms in São Paulo state and were housed in a semi-open stall during the study. The animals had their hair clipped from the third to the fifth intercostal spaces on both sides of the chest, from the sternal region to the glenohumeral joint, and seven electrodes were positioned in a diagonal configuration. Decoding of the recordings was performed using specialized software and in order to minimize digital mistakes, all of the beats marked as ectopic by the software were manually revised by the authors. Mean heart rate was 83.2 ± 11.06 beats per min (bpm), maximum heart rate was 147.1 ± 11.05 bpm, and minimum heart rate was 53.7 ± 7.45 bpm. In 90% of the calves, normal sinus [...]

PARÂMETROS DE ARRITMOGÊNESE E DEFORMAÇÃO MIOCÁRDICA EM CUTIAS (Dasyprocta prymnolopha) CRIADAS EM CATIVEIRO

As cardiopatias afetam humanos e animais, necessitando de investigação para entendimento das alterações hemodinâmicas. Visto isso, o estudo de novos modelos animais é importante para a padronização de parâmetros fisiológicos cardíacos, com a cutia representando um modelo de estudo de arritmia e função miocárdica. Objetivou-se avaliar os valores de normalidade de eletrocardiografia de alta resolução (ECGAr), vetorcardiografia (VCG), strain ventricular e atrial, strain rate ventricular por Speckle Tracking (2D-STE) e pressão arterial (PA) em cutias contidas fisicamente e sedadas com cetamina-xilazina e butorfanol. Foram utilizadas oito cutias hígidas criadas no Núcleo de Estudos, Produção e Preservação de Animais Silvestres NEPPAS/UFPI, as quais foram examinadas quanto à pressão arterial, exames eletrocardiográficos de alta resolução, eletrovetocardiografia e ecocardiografia, com analise de deformação por speckle tracking, especificando os índices de pressão arterial sistólica (PAS), diastólica (PAD) e média (PAM), em 2D-STE as variáveis ventriculares strain radial (StRad), strain longitudinal (StLong), strain circunferencial endocárdico e epicárdico (StenCirc e StepCirc) strain rate radial (StrRad), strain rate longitudinal endocárdico (StrenLong), strain rate circunferencial endocárdico e epicárdico (StRenCirc e StRepCirc), picos de strain atrial longitudinal (PALS), contração atrial(PACS) e o índice de deformação de contração (CSI), bem como a avaliação em ECGAr do QRS filtrado (dQRS), a duração dos sinais de alta frequência e baixa amplitude na porção final do complexo QRS filtrado (LAS < de 40 V) e o RMS, raiz quadrada da voltagem média dos últimos 40 milissegundos do QRS filtrado contidas fisicamente e sedadas em dois protocolos, cetamina-xilazina e butorfanol. No VCG foram analisados os ângulos de P, QRS e QRS-T nos planos horizontal (PH), sagital (PS) e frontal (PF), sua distribuição e inscrição espacial. Nos animais contidos fisicamente observou-se ECGAr, dQRS total de 93.25 ± 9.51 ms, LAS < 40 de 28.50 ± 4.65ms e RMS de 95.50 ± 29.75, com uma diminuição do dQRS nos animais tratados com cetamina-xilazina e diminuição nos animais tratados com butorfanol, foi demonstrado abrangência de vetor médio entre 0 e 180 graus com direcionamento de vetor de despolarização médio para baixo e esquerda e para trás, usando junção de PF, PH e OS. Observou-se mudança no sQRS com elevação do índice nos animais tratados com cetamina-xilazina. Dados fisiológicos de 2D-STE obtidos foram, StenCirc de -21,78 ± 3,61%, StepCirc de -9,26 ± 1,79% StRenCirc -2,81 ± 0,55s-1, StRepCirc de -1,08 ± 0,12s-1 StenLong. -18,85 ± 1,65% StRenLong -1,72 ±0,20s-1 StRad 28,50 ± 10,20% e StRrad 2,64 ± 0,54s-1, onde em ambos os protocolos de sedação reduziram significativamente a deformação longitudinal de fibras miocárdicas ventriculares. Em relação ao strain atrial com valores PALS, PACS e CSI, de 25,18 ± 5,32%, 12,65 ± 4,87% e 49,12 ± 13,00% com diminuição de valores de PACS no grupo tratado com cetamina-xilazina e pressão arterial com variáveis PAS, PAD, e PAM de 147,50 ± 8.45, 95,62 ± 6.78 e 112,88 ± 6.33 mmHg, respectivamente. A cutia apresenta-se como um modelo cardiológico relevante por apresentar morfofisiologia favorável à obtenção das variáveis, conferindo atributo fidedigno para estudos da deformação, remodelamento e arritmogenicidade cardíaca.

Heart diseases affect humans and animals, requiring investigation to understand hemodynamic and tissue changes. In view of this, the study of new animal models is important for the standardization of physiological cardiac parameters, with the agouti representing a good model. The aim of the study was to evaluate the normality values of high-resolution electrocardiography (HREGG), vectorcardiography (VCG), ventricular and atrial strain, ventricular strain rate by Speckle Tracking (2D-STE) and blood pressure (BP) in physically contained agouti and sedated with ketamine-xylazine and butorphanol. Eight healthy agouti created at the NEPPAS/UFPI Study, Production and Preservation Center for Wild Animals, which were examined for blood pressure, high-resolution electrocardiographic tests, electrovetocardiography and echocardiography, with deformation analysis by speckle tracking, specifying the systolic (SBP), diastolic (DBP) and mean (MAP) blood pressure indices, in 2D-STE the variables ventricular radial strain (StRad), longitudinal strain (StLong), endocardial and epicardial circumferential strain (StenCirc and StepCirc) strain rate radial (StrRad), longitudinal endocardial strain rate (SrenLong), circumferential endocardial and epicardial strain rate (StRenCirc and StRepCirc), longitudinal atrial strain peaks (PALS), atrial contraction (PACS) and the contraction strain index (CSI), as well as the rECG evaluation of the filtered QRS (dQRS), the duration of high frequency and low amplitude signals in the final portion of the filtered QRS complex (LAS < d and 40 V) and the RMS, square root of the mean voltage of the last 40 milliseconds of the filtered QRS physically contained and sedated in two protocols, ketamine-xylazine and butorphanol. In the VCG, the P, QRS and QRS-T angles in the horizontal (PH), Sagittal (PS) and frontal (PF) planes, their distribution and spatial inscription were analyzed. In physically restrained animals, ECGAr, total dQRS of 93.25 ± 9.51 ms, LAS < 40 of 28.50 ± 4.65 ms and RMS of 95.50 ± 29.75 ms were observed, with a decrease in dQRS in animals treated with ketamine-xylazine and a decrease in animals treated with butorphanol, was demonstrated mean vector range between 0 and 180 degrees with mean depolarization vector driving down and left and back using PF, PH and OS junction. A change in the sQRS with an increase in the index was observed in animals treated with ketamine-xylazine. Physiological 2D-STE data obtained were, StenCirc of -21.78 ± 3.61%, StepCirc of -9.26 ± 1.79% StRenCirc -2.81 ± 0.55s-1, StRepCirc of - 1.08 ± 0.12s-1 StenLong. -18.85 ± 1.65% StRenLong -1.72 ±0.20s-1 StRad 28.50 ± 10.20% and StRrad 2.64 ± 0.54s-1, where in both sedation protocols they significantly reduced the longitudinal deformation of ventricular myocardial fibers. Regarding atrial strain with PALS, PACS and CSI values of 25.18 ± 5.32%, 12.65 ± 4.87% and 49.12 ± 13.00% with decreased PACS values in the group treated with ketamine-xylazine and blood pressure with variables SBP, DBP, and MAP of 147.50 ± 8.45, 95.62 ± 6.78 and 112.88 ± 6.33 mmHg, respectively. The agouti is a relevant cardiology model for presenting a favorable morphophysiology for obtaining the variables, providing a reliable attribute for studies of deformation, remodeling and cardiac arrhythmogenicity.

Electrocardiographic patterns of Mangalarga Marchador horses before and after implementation of the marcha gait / Padrões eletrocardiográficos em equinos da raça Mangalarga Marchador antes e após a execução da marcha

The aim of this study was to evaluate the electrocardiographic parameters in Mangalarga Marchador horses submitted to marcha exercise. Twenty-four Mangalarga Marchador horses, thirteen females and eleven males, 6.4±2.7 years old with a mean weight of 428.3±24.7kg, were used. Electrocardiograms were recorded in two different moments: rest and immediately after exercise (40 minutes of aerobic exercise, marcha gait). The electrocardiographic variables analyzed were cardiac rhythm, heart rate (HR), duration of P wave, QRS complex, PR and QT intervals, amplitudes of P, R and T waves, and analysis of QT corrected (QTc) according to Bazett's formula (QT/RR). Variables were analyzed for normality with Kolmogorov-Smirnov test and paired t-test, considering P 0.05. Rhythm analysis revealed 91.7% of sinus rhythm and 8.3% of sinus arrhythmia in rest, with mean HR of 45.7±12.7 beats minute-1, and 100% of sinus tachycardia, with mean HR of 77.3±13.5 beats minute-1 after exercise (P 0.0001). In post-exercise, it was possible to observe decreases in P wave duration (P=0.0121), PR interval (P=0.0007) and QT interval (P 0.0001) and increase of QTc (P=0.0039) and R wave amplitude (P=0.0033). There were no significant differences for amplitude of P and T waves and QRS complex related to atrioventricular enlargement. Although QT interval decreased after exercise, there was an increase on QTc after exercise, indicating changes in ventricular repolarization. It was possible to conclude that the imposed exercise (marcha gait) led to electrocardiographic alterations without causing pathological arrhythmias.(AU)

O objetivo deste estudo foi avaliar os parâmetros eletrocardiográficos de equinos da raça Mangalarga Marchador antes e após a execução da marcha. Para tal, foram usados 24 equinos, treze fêmeas e onze machos, com idade média de 6,4±2,7 anos e peso médio de 428,3±24,7kg. Eletrocardiogramas foram registrados em dois momentos: antes e imediatamente após atividade física (40 minutos de marcha). As variáveis eletrocardiográficas analisadas foram ritmo cardíaco, frequência cardíaca (FC), duração da onda P, complexo QRS, intervalos PR e QT, amplitudes das ondas P, R e T e análise do QT corrigida (QTc) de acordo com a fórmula de Bazett (QT/RR). As variáveis foram analisadas quanto à normalidade (teste de Kolmogorov-Smirnov), seguido da comparação usando teste-t pareado (P 0,05). A análise revelou 91,7% de ritmo sinusal e 8,3% de arritmia sinusal no repouso, com FC média de 45,7±12,7bpm e 100% de taquicardia sinusal após o exercício, com FC média de 77,3±13,5bpm (P 0,0001). No pós-exercício, foi possível observar reduções significativas na duração da onda P (P=0,0121), no intervalo PR (P=0,0007) e no intervalo QT (P 0,0001), além de aumentos significativos de QTc (P=0,0039) e amplitude da onda R (P=0,0033). Não foram registradas diferenças para a amplitude das ondas P e T e na duração do complexo QRS. Apesar da redução no intervalo QT após o exercício, houve um aumento no QTc, indicando alterações na repolarização ventricular. Foi possível concluir que a atividade física (marcha) gerou alterações eletrocardiográficas, sem causar arritmias patológicas.(AU)