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1.
Biomed Pharmacother ; 120: 109500, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31600641

RESUMO

OBJECTIVES: Findings from prior investigations show that left stellate ganglion (LSG) inhibitory approaches protect the heart from ventricular arrhythmias (VAs) caused by acute myocardial infarction (AMI), which still remain many side effects. Targeted transient receptor potential vanilloid 1/tyrosine hydroxylase (TRPV-1/TH) expressing sympathetic neurons ablation is a novel neuro-ablative strategy. The aim of this investigation was to explore if targeted molecular neuro-ablative strategy by resiniferatoxin (RTX) stellate microinjection could protect against ischemia-induced VAs. METHODS: Twenty-four anesthetized beagles were assigned to a control group (n = 12) and RTX group (n = 12) in a random manner. Targeted molecular neuro-ablative was produced by RTX stellate microinjection and DMSO was microinjected into LSG in the same way as control. Plasma norepinephrine (NE) level, heart rate variability (HRV), Tpeak-Tend interval (Tp-Te), LSG neural activity and function, ventricular effective refractory period (ERP), beat-to-beat variability of repolarization (BVR) and ventricular action potential duration (APD) were measured at baseline and 60 min after RTX or DMSO microinjection. AMI model was established by the ligation of left anterior descending coronary artery and 60-minute electrocardiography was continuously recorded for VAs analysis. Subsequently, HRV, Tp-Te, plasma NE level from jugular vein and coronary sinus, LSG neural activity and function, ventricular ERP, ventricular APD, BVR, action potential duration alternans (APDA) cycle length and ventricular fibrillation threshold (VFT) were evaluated after AMI. Finally, tissue collection of LSG was performed for examining the TRPV-1, nerve growth factor (NGF) protein and c-fos protein. RESULTS: TRPV-1 was highly expressed in the TH-expressing neurons and RTX injection significantly ablated TRPV-1/TH-positive neurons in LSG. Compared with baseline, RTX stellate microinjection significantly reduced plasma NE level, the sympathetic component of HRV, LSG neural activity and LSG function, shortened Tp-Te, prolonged ventricular ERP and APD, but there were no remarkable differences existed for control group. AMI resulted in the significant raise in plasma NE level from jugular vein and coronary sinus, the sympathetic component of HRV, LSG neural activity and LSG function, the marked prolongation in Tp-Te and BVR, the significant decrease in ERP and APD from ischemia area, and the increase in APDA cycle length in the ischemic region of the control group, which were remarkably attenuated in the RTX group. RTX pretreatment markedly rose the VFT in the RTX group. Furthermore, the AMI-triggered VAs was significantly prevented by RTX injection in the RTX group. RTX microinjection down-regulated significantly TRPV-1, NGF and c-fos expression in the LSG compared with the control group. CONCLUSION: Targeted ablation of TRPV-1/TH positive sympathetic neurons induced by RTX stellate microinjection could suppress ischemia-induced cardiac autonomic imbalances and cardiac electrophysiology instability to protect against AMI-induced VAs.


Assuntos
Arritmias Cardíacas/prevenção & controle , Arritmias Cardíacas/veterinária , Diterpenos/farmacologia , Isquemia Miocárdica , Neurônios/fisiologia , Gânglio Estrelado/citologia , Canais de Cátion TRPV/metabolismo , Técnicas de Ablação , Animais , Cães , Regulação da Expressão Gênica/efeitos dos fármacos , Canais de Cátion TRPV/genética , Tirosina 3-Mono-Oxigenase/metabolismo , Fibrilação Ventricular/etiologia , Fibrilação Ventricular/fisiopatologia
2.
Pesqui. vet. bras ; 39(8): 635-642, Aug. 2019. tab, graf
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-1040724

RESUMO

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)


Assuntos
Animais , Cães , Arritmias Cardíacas/veterinária , Sistema Nervoso Simpático/fisiopatologia , Displasia Arritmogênica Ventricular Direita/veterinária , Morte Súbita/etiologia , Morte Súbita/veterinária , Frequência Cardíaca
3.
J Vet Intern Med ; 33(5): 1902-1908, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31317600

RESUMO

BACKGROUND: Cardiac cachexia, loss of muscle mass associated with congestive heart failure (CHF), is associated with increased morbidity and shorter survival times in people, but an association between cardiac cachexia and survival has not been reported in dogs. OBJECTIVES: To determine the prevalence of cachexia and its associations with clinical, laboratory, and survival data in dogs with CHF. ANIMALS: Two hundred sixty-nine dogs with CHF. METHODS: Retrospective cohort study. Cachexia was defined by 1 of 2 definitions: (1) mild, moderate, or severe muscle loss or (2) weight loss of ≥5% in 12 months or less. Variables were compared between dogs with and without cachexia. RESULTS: One hundred thirty of 269 dogs (48.3%) had cardiac cachexia based on muscle loss, whereas 67 of 159 dogs (42.1%) with pre-evaluation body weights had cachexia based on weight loss. Dogs with cachexia (based on muscle loss) were significantly older (P = .05), more likely to have a cardiac arrhythmia (P = .02), had higher chloride concentrations (P = .04), and had a lower body condition score (P < .001), hematocrit (P = .006), hemoglobin (P = .006), and albumin (P = .004) concentrations. On multivariable analysis, cachexia (P = .05), clinically important tachyarrhythmias (P < .001), azotemia (P < .001), and being under- or overweight (both P = .003) were associated with shorter survival times. CONCLUSIONS AND CLINICAL IMPORTANCE: Cardiac cachexia in common in dogs with CHF and is associated with significantly shorter survival. This emphasizes the importance of preventing, diagnosing, and treating muscle loss in dogs with CHF.


Assuntos
Caquexia/veterinária , Doenças do Cão , Insuficiência Cardíaca/veterinária , Fatores Etários , Animais , Arritmias Cardíacas/veterinária , Azotemia/veterinária , Caquexia/complicações , Estudos de Coortes , Cães , Insuficiência Cardíaca/complicações , Estudos Retrospectivos , Análise de Sobrevida , Taquicardia/veterinária , Perda de Peso
4.
J Vet Cardiol ; 23: 38-44, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31174728

RESUMO

A four-year-old Japanese Akita was referred for investigation of lethargy, exercise intolerance, and an irregular heart rhythm. He was diagnosed with atrial fibrillation, a complex ventricular arrhythmia, and hypothyroidism. Echocardiography identified a nest of anomalous vessels surrounding the heart and shunting into the pulmonary artery. Computed tomography confirmed a coronary arteriovenous malformation consisting of a coronary-to-pulmonary arterial communication and an associated complex nest of tortuous vessels, which was thought to be an incidental finding. Clinical signs improved with levothyroxine and antiarrhythmic treatment. Describing an unusual coronary artery anomaly as well, this case serves as a reminder to critically evaluate the hemodynamic significance of structural cardiac disease and to screen for systemic disease in patients with arrhythmias.


Assuntos
Arritmias Cardíacas/veterinária , Malformações Arteriovenosas/veterinária , Doenças do Cão/diagnóstico por imagem , Hipotireoidismo/veterinária , Animais , Arritmias Cardíacas/tratamento farmacológico , Malformações Arteriovenosas/diagnóstico por imagem , Fibrilação Atrial/veterinária , Anomalias dos Vasos Coronários/diagnóstico por imagem , Anomalias dos Vasos Coronários/veterinária , Doenças do Cão/congênito , Doenças do Cão/tratamento farmacológico , Cães , Ecocardiografia/veterinária , Hipotireoidismo/tratamento farmacológico , Masculino , Tiroxina/uso terapêutico , Tomografia Computadorizada por Raios X/veterinária
5.
Res Vet Sci ; 125: 141-147, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31228737

RESUMO

OBJECTIVE: Evaluate accuracy and utility of a smartphone-based ECG device compared to a standard base-apex lead ECG in horses. METHODS: ECGs were acquired prospectively from 28 client-owned horses at 2 equine referral hospitals. Twenty-five pairs of 30-s ECG recordings were acquired simultaneously from 23 horses with a smartphone ECG device (a bi-polar single lead recorder coupled to a smartphone with an ECG application) and with a standard base-apex lead ECG; 2 horses provided two pairs of simultaneously acquired ECGs. In one horse, the ECGs pairs were recorded immediately sequentially. An additional 7 smartphone ECGs were recorded from 5 horses without contemporaneous reference ECGs. Three observers independently evaluated all ECGs without knowledge of ECG pairing. Inter- and intra-observer agreement between the 2 ECG modalities was evaluated for rhythm diagnosis and QRS polarity. Heart rate agreement was also evaluated. RESULTS: Intra-observer agreement for rhythm assessment was very high; one observer diagnosed the same cardiac rhythm on both recordings in 24/26 instances and two observers agreed in 25/26 instances. The polarity of the QRS complex was similar on ECGs acquired simultaneously by both systems. Heart rates calculated from ECG pairs were within 1 beat of each other. CONCLUSIONS: The smartphone-acquired ECG accurately identified cardiac rhythm and heart rate in most horses. In one case, small size of the complexes precluded identification of P waves on smartphone-acquired ECGs, resulting in a misdiagnosis. The smartphone-acquired ECG device might allow veterinarians to evaluate and monitor cardiac arrhythmias relatively inexpensively in field or hospital settings.


Assuntos
Arritmias Cardíacas/veterinária , Eletrocardiografia/veterinária , Doenças dos Cavalos/diagnóstico , Cavalos/fisiologia , Smartphone/instrumentação , Animais , Arritmias Cardíacas/diagnóstico , Eletrocardiografia/instrumentação , Eletrocardiografia/métodos , Feminino , Frequência Cardíaca , Masculino , Estudos Prospectivos
6.
Aust Vet J ; 97(6): 202-207, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31136688

RESUMO

BACKGROUND: Intoxication following ingestion of the popular garden shrub 'Yesterday, today, tomorrow' (Brunfelsia sp.) is known to result in gastrointestinal and central nervous system clinical signs in dogs. CASE REPORT: A 2-year-old dog developed acute-onset vomiting, profuse diarrhoea and ptyalism after unsupervised access to an enclosed backyard that contained a Brunfelsia sp. shrub. During initial assessment the watery diarrhoea contained plant material and the dog appeared painful on abdominal palpation. Soon after admission, severe neurological abnormalities developed. Decontamination was undertaken by gastric and colonic lavage under general anaesthesia, but on recovery the patient had generalised seizures that were unresponsive to benzodiazepines. Following treatment with multiple antiepileptic medications and endotracheal intubation for loss of gag reflex, the patient developed respiratory failure requiring mechanical ventilation. Four days after initial presentation, the patient developed cardiac dysrhythmia leading to fatal cardiac arrest. Plant material recovered from the shrub and the patient's gastrointestinal tract were identified as Brunfelsia spp. CONCLUSION: This is the first report of hypoventilation, severe cardiac dysrhythmia and cardiac arrest associated with Brunfelsia sp. intoxication in a dog. Previous reports described clinical signs of gastrointestinal disease and mild cardiac dysrhythmia progressing to seizure activity and opisthotonus. Electrocardiography should form part of patient monitoring and mechanical ventilation considered for patients that develop respiratory failure, especially if massive ingestion is suspected.


Assuntos
Arritmias Cardíacas/veterinária , Doenças do Cão/etiologia , Parada Cardíaca/veterinária , Hipoventilação/veterinária , Intoxicação por Plantas/veterinária , Solanaceae/envenenamento , Animais , Arritmias Cardíacas/induzido quimicamente , Arritmias Cardíacas/etiologia , Doenças do Cão/terapia , Cães , Feminino , Parada Cardíaca/etiologia , Hipoventilação/etiologia , Intoxicação por Plantas/terapia , Convulsões/veterinária
7.
J Vet Intern Med ; 33(4): 1695-1706, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31119786

RESUMO

BACKGROUND: Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, causes sudden death and chronic heart disease with no currently approved treatment. OBJECTIVE: To report epidemiologic and select cardiac characteristics associated with T. cruzi infection in dogs presenting to a teaching hospital in Texas. ANIMALS: Three hundred seventy-five client-owned dogs. METHODS: A retrospective search of medical records identified dogs tested for T. cruzi antibodies or with histologic T. cruzi parasites. Data retrieved included signalment, location of residence, reported reason for testing, cardiac troponin I (cTnI) concentration, and ECG abnormalities. RESULTS: Trypanosoma cruzi-infected dogs (N = 63, 16.8%) were significantly younger than negative dogs (N = 312) (mean, 5.9 ± 3.8 versus 7.4 ± 4.0 years; P = .007) with no difference by sex or breed. Ninety-one breeds were tested; the highest percent infected were non-sporting (10/35; 29%) and toy breed (10/42; 24%) groups. The odds of infection were 13 times greater among dogs with an infected housemate or littermate (95% confidence interval [CI], 3.94-50.45; P < .001). Infected dogs were more likely to have ventricular arrhythmias (odds ratio [OR], 2.19; 95% CI, 1.15-4.33, P = .02), combinations of ECG abnormalities (OR, 2.91; 95% CI, 1.37-5.99; P = .004), and cTnI >0.129 ng/mL (ADVIA; OR, 10.71; 95% CI, 1.60-212.21; P = .035). CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs infected with T. cruzi were identified in Texas in many breed groups including breeds affected by well-described heart diseases that mimic Chagas disease suggesting a need for increased awareness, including knowledge of when to consider testing.


Assuntos
Doença de Chagas/veterinária , Doenças do Cão/parasitologia , Cardiopatias/veterinária , Animais , Arritmias Cardíacas/veterinária , Doença de Chagas/complicações , Doença de Chagas/epidemiologia , Doenças do Cão/epidemiologia , Cães , Eletrocardiografia/veterinária , Feminino , Cardiopatias/fisiopatologia , Masculino , Estudos Retrospectivos , Fatores de Risco , Texas/epidemiologia , Troponina I/sangue , Trypanosoma cruzi/isolamento & purificação
8.
Top Companion Anim Med ; 35: 31-37, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31122685

RESUMO

Canine Monocytic Ehrlichiosis (CME) is a disease of worldwide distribution caused by the bacteria Ehrlichia canis, appearing primarily in hot climates due to the massive prevalence of its vector, the tick Rhipicephalus sanguineus. Previous studies have shown that dogs afflicted by CME in the chronic phase can develop infectious myocarditis, arrhythmias, and alterations in heart rate variability (HRV), but there are few studies correlating cardiac diseases with the acute phase of CME. This study aims at assessing electric cardiac alterations and HRV in the time and frequency domains during the acute phase of CME. This study assessed 22 animals divided into 2 distinct groups: the control group, comprised by 10 healthy dogs, and the sick group, comprised of 12 dogs infected naturally with ehrlichiosis which presented clinical and hematological signs compatible with the acute phase of the disease. The animals underwent conventional and Holter electrocardiographic evaluations, systolic blood pressure measurement, complete blood count and biochemical assays (urea, creatinine, alanine aminotransferase (ALT), alkaline phosphatase (AP), and gamma glutamyl transferase (GGT)). The sick group presented higher activity in the sympathetic nervous system than in the parasympathetic nervous system, manifest as a significant increase in mean heart rate and a reduction in the HRV indexes for the time and frequency domains. The frequency-domain HRV indexes presented sympathetic prevalence during the sleep and vigilance states. Sinus tachycardia was the predominant heart rhythm in 58.33% of the animals. The mean systolic blood pressure diverged between the groups and no significant arrhythmias were observed during monitoring. The serum concentrations of urea, creatinine, AP, ALT, and GGT were within the established reference values for the species. We observed no indication that there was enough time during the acute phase for the disease to evolve in a way that resulted in arrhythmias, as is common in the chronic phase, but we observed that animals in the acute phase already present reduced HRV indexes.


Assuntos
Doenças do Cão/microbiologia , Ehrlichiose/veterinária , Eletrocardiografia/veterinária , Animais , Arritmias Cardíacas/veterinária , Pressão Sanguínea , Estudos de Casos e Controles , Cães , Ehrlichia canis , Ehrlichiose/complicações , Eletrocardiografia Ambulatorial/veterinária , Feminino , Frequência Cardíaca/fisiologia , Masculino , Taquicardia Sinusal/veterinária
9.
Vet Clin North Am Equine Pract ; 35(1): 175-190, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30871825

RESUMO

Horses have a high prevalence of resting arrhythmias, cardiac murmurs, and valvular regurgitation, and training can increase the prevalence. This makes it challenging for equine veterinarians who are asked to evaluate horses for poor performance to determine the clinical relevance of some findings. In addition, cardiac disease has the potential to cause collapse or sudden death, putting both the horse and rider at risk. Further diagnostics, such as echocardiograms and resting and exercising ECGs can help to sort out the impact of an abnormality found on resting physical examination. However uncertainty over the importance of some findings continues to exist.


Assuntos
Tolerância ao Exercício/fisiologia , Doenças dos Cavalos/diagnóstico , Doenças dos Cavalos/fisiopatologia , Animais , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/veterinária , Cavalos , Condicionamento Físico Animal
10.
Vet Clin North Am Equine Pract ; 35(1): 65-83, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30871826

RESUMO

Analyzing electrocardiographic (ECG) recordings, making a diagnosis and assessment of any arrhythmias present, is an important part of the workup of many equine cases. Accurate analysis requires a good-quality recording, free of as many artifacts as possible, with clear P-QRS-T complex morphology. For sustained arrhythmias, short-term recordings are sufficient to make the appropriate diagnosis before instigating treatment. Longer-term recordings are essential for arrhythmias that are paroxysmal, intermittent, or occurring infrequently, while exercising ECGs are required for arrhythmias associated with physical activity. A stepwise, logical approach to ECG analysis will help the observer to recognize and correctly diagnose any arrhythmias present.


Assuntos
Arritmias Cardíacas/veterinária , Eletrocardiografia/veterinária , Doenças dos Cavalos/diagnóstico , Animais , Arritmias Cardíacas/diagnóstico , Eletrocardiografia/métodos , Cavalos
11.
Vet Clin North Am Equine Pract ; 35(1): 191-204, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30871830

RESUMO

Arrhythmias detected on prepurchase examination should be confirmed with an ECG. Exercising ECG determines if the arrhythmia is overdriven during exercise or is a safety concern. An echocardiogram is needed in all horses with a grade 3/6 or louder mid to late systolic, holosystolic, or pansystolic murmur or any holodiastolic decrescendo murmur to identify the cardiac abnormality and its hemodynamic impact. Most horses with arrhythmias and murmurs have a normal performance career and life expectancy and are insurable. Risks for sudden death and congestive heart failure associated with the common murmurs and arrhythmias are identified, because these horses cannot be insured.


Assuntos
Arritmias Cardíacas/veterinária , Sopros Cardíacos/veterinária , Doenças dos Cavalos/diagnóstico , Exame Físico/veterinária , Animais , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatologia , Sopros Cardíacos/diagnóstico , Sopros Cardíacos/fisiopatologia , Doenças dos Cavalos/fisiopatologia , Cavalos , Seguro
12.
Vet Clin North Am Equine Pract ; 35(1): 85-102, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30871832

RESUMO

Arrhythmias are common in horses. Sinus arrhythmia and first- and second-degree atrioventricular block are frequently found physiologic arrhythmias, but should immediately disappear after stress or exercise. Atrial premature depolarizations are usually not associated with poor performance, but are a potential trigger for atrial fibrillation. Atrial fibrillation results in an abnormal ventricular response during exercise and poses a risk for collapse in some horses. This arrhythmia can usually be treated by quinidine sulfate or transvenous electrical cardioversion. Ventricular premature depolarizations, especially when associated with structural heart disease, may be a risk factor for ventricular tachycardia or even ventricular fibrillation.


Assuntos
Arritmias Cardíacas/veterinária , Doenças dos Cavalos/diagnóstico , Doenças dos Cavalos/terapia , Animais , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/terapia , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/terapia , Fibrilação Atrial/veterinária , Cavalos
13.
Vet Clin North Am Equine Pract ; 35(1): 43-64, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30826106

RESUMO

This article provides an overview on the principles of transthoracic echocardiography in horses. Indications for echocardiography, equipment, and technical considerations are discussed and a systematic approach for a complete echocardiographic examination in horses is described. Methods for assessment of chamber dimensions, allometric scaling of measurements, assessment of systolic and diastolic ventricular function, assessment of atrial function, hemodynamic assessment, and evaluation of valvular regurgitation are explained, focusing on traditional 2-dimensional (2D), motion-mode, and Doppler echocardiographic methods. Selected applications of newer echocardiographic methods, such as tissue Doppler imaging and 2D speckle tracking are also described.


Assuntos
Arritmias Cardíacas/veterinária , Ecocardiografia/veterinária , Doenças dos Cavalos/diagnóstico por imagem , Animais , Arritmias Cardíacas/diagnóstico por imagem , Ecocardiografia/métodos , Cavalos
14.
J Vet Pharmacol Ther ; 42(3): 285-293, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30724383

RESUMO

This study aimed to assess the effects of incremental doses of dobutamine on diastolic function in healthy and rapid ventricular apical pacing (RVAP)-induced cardiac dysfunction anesthetized dogs. Inotropic and lusitropic effects of dobutamine (2, 4, 8, and 12 µg kg-1  min-1 ) were assessed through left ventricle (LV) pressure-volume relation and Doppler echocardiography in six female dogs before and after 8 weeks of RVAP. Peak rate of LV pressure fall (-dP/dtmin ) improved with doses >4 µg kg-1  min-1 in healthy (4,490 ± 970 vs. 3,265 ± 471 mmHg/s, p < 0.05) and >8 µg kg-1  min-1 in RVAP dogs (3,385 ± 1,122 vs. 1,864 ± 849 mmHg/s, p < 0.05) while the time constant of relaxation (tau) reduced with doses >4 µg kg-1  min-1 in both groups (healthy: 24.0 ± 3.7 vs. 28.2 ± 4.9 ms; RVAP: 32.6 ± 8.5 vs. 37.5 ± 11.4 ms, p < 0.05) comparing with baseline. Indices of relaxation (-dP/dtmin and tau) suggested preserved lusitropic response in contrast with markedly reduced indices of contractility in the RVAP group compared with healthy group at same infusion rates. Doppler echocardiography showed significant reduction of elastic recoil in failing hearts. The results of this study demonstrated maximal positive lusitropic effects of dobutamine at a dose of 8 µg kg-1  min-1 in ventricular pacing-induced cardiac dysfunction without further impairment of ventricular filling.


Assuntos
Arritmias Cardíacas/veterinária , Cardiotônicos/uso terapêutico , Dobutamina/uso terapêutico , Doenças do Cão/tratamento farmacológico , Animais , Arritmias Cardíacas/tratamento farmacológico , Arritmias Cardíacas/fisiopatologia , Cardiotônicos/administração & dosagem , Dobutamina/administração & dosagem , Cães , Relação Dose-Resposta a Droga , Ecocardiografia Doppler/veterinária , Feminino , Ventrículos do Coração/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Contração Miocárdica/efeitos dos fármacos , Função Ventricular/efeitos dos fármacos
15.
J Vet Cardiol ; 22: 40-50, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30792165

RESUMO

In the 60 years since the first human implant of a cardiac pacemaker, tremendous improvements have been made to devices themselves as well as the lead systems. Improvement in battery materials has allowed for production of smaller devices with greater longevity and a vast array of technologies allowing for communication between the device and the operator. Lead wires, typically to as the weakest part of the pacing system, have also seen a metamorphosis as improvements in conductor materials and hybrid insulation have been shown to improve reliability. With the recent development of leadless pacing systems, the downfalls of implantable leads can be avoided. These improvements have allowed a more widespread use of cardiac pacing in veterinary applications since the first reported canine implant in 1967.


Assuntos
Estimulação Cardíaca Artificial/história , Marca-Passo Artificial/história , Animais , Arritmias Cardíacas/terapia , Arritmias Cardíacas/veterinária , Estimulação Cardíaca Artificial/veterinária , Desenho de Equipamento , História do Século XX , História do Século XXI , Humanos , Marca-Passo Artificial/normas , Marca-Passo Artificial/veterinária
16.
J Vet Cardiol ; 21: 67-78, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30797447

RESUMO

INTRODUCTION: The objectives of this study were to describe the changes in clinical cardiovascular examination variables over a competition season in groups of competitive eventing and endurance horses and to compare these findings to non-competitive controls of the same breeds. ANIMALS: This study included two eventing horses, 11 endurance horses, and 13 eventing and seven endurance control breed-matched horses. MATERIALS AND METHODS: Cardiovascular examinations were performed before starting the competition season, in the middle and at the peak/end of the competition season. Examinations included auscultation of the heart; M-mode echocardiographic measurements and calculated values; left atrial, pulmonary artery, and aortic diameters; color flow Doppler; exercise electrocardiograms (ECG) measuring peak heart rates and quantifying premature complexes; and 24-h continuous ECGs quantifying premature complexes per hour. RESULTS: Auscultation, echocardiograms, arrhythmias during exercise, and 24-h continuous ECGs did not change significantly throughout the season (p > 0.05 for all variables). CONCLUSION: Cardiovascular examination variables of eventing and endurance horses throughout a competition season are reported here for the first time. Although the present study did not reveal significant changes, data should be interpreted carefully as only a small number of horses were examined.


Assuntos
Fenômenos Fisiológicos Cardiovasculares , Cavalos/fisiologia , Resistência Física/fisiologia , Animais , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/veterinária , Sistema Cardiovascular/diagnóstico por imagem , Ecocardiografia/veterinária , Eletrocardiografia/veterinária , Feminino , Masculino , Condicionamento Físico Animal/fisiologia , Corrida/fisiologia
18.
Vet J ; 243: 21-25, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30606435

RESUMO

Arrhythmias can complicate cardiac disease in cats and are a potential cause of sudden death. The aim of this study was to evaluate the presence and nature of cardiac arrhythmias, and the potential correlation between plasma serum troponin I (cTnI) concentrations and the presence or severity of arrhythmias in cats with decompensated (dHCM) and compensated hypertrophic cardiomyopathy (cHCM). Forty one client-owned cats were studied: 16 with cHCM, 15 with dHCM and 10 healthy control cats. Physical examination, echocardiography, cTnI and 24-h Holter recordings were obtained in all cats and thoracic radiographs in cats with dHCM. Cats in both HCM groups were followed for 1 year after their initial Holter examination. The median (range) number of ventricular premature complexes (VPCs) over 24h was 867 (1-35,160) in cats with dHCM, 431 (0-18,919) in cats with cHCM and 2 (0-13) in healthy control cats. The median number of episodes of ventricular tachycardia (VTach) was 0 (0-1497) in dHCM and 0.5 (0-91) in cats with cHCM. The number of VPCs, VTach episodes and heart rate was not different between the HCM groups. Plasma serum troponin I was highest in the cats with dHCM, but there was no correlation between cTnI concentration and the number of arrhythmias. Thirteen of 31 cats with HCM died, but an association with the presence and complexity of ventricular arrhythmias was not observed. Compared to healthy cats, ventricular arrhythmias were common in cats with cHCM and dHCM, but neither presence nor complexity of arrhythmias could be linked to prognosis.


Assuntos
Arritmias Cardíacas/veterinária , Cardiomiopatia Hipertrófica/veterinária , Doenças do Gato/fisiopatologia , Eletrocardiografia Ambulatorial/veterinária , Frequência Cardíaca , Ventrículos do Coração/fisiopatologia , Animais , Arritmias Cardíacas/epidemiologia , Arritmias Cardíacas/fisiopatologia , Cardiomiopatia Hipertrófica/epidemiologia , Cardiomiopatia Hipertrófica/fisiopatologia , Doenças do Gato/epidemiologia , Gatos , Feminino , Masculino
19.
J Vet Intern Med ; 33(1): 212-224, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30520119

RESUMO

BACKGROUND: Little is known about normal heart rate variability (HRV) in horses during exercise. It can be difficult to separate premature beats from normal beat-to-beat variation at higher heart rates. OBJECTIVES: The aim was to quantify HRV in healthy horses during a high-speed treadmill-standardized exercise test (HSET) and to compare with the HRV in horses observed to have arrhythmias during exercise. ANIMALS: Thirteen healthy horses (Group H), 30 horses with arrhythmias (Group A), and 11 horses with poor performance but no observed arrhythmias (Group O). METHODS: Prospective, observational study. All horses performed a HSET with simultaneous electrocardiograph (ECG) recorded. The ECGs were corrected for artifacts, and arrhythmias noted. Percent instantaneous beat-to-beat cycle length variation (% R-R variation) was calculated, and HRV analyses were performed on trot, canter, and recovery segments. RESULTS: Group H showed between -4.4 and +3.8% R-R variation during trot and between -6.1 and +5.4% R-R variation during the canter phase of the HSET. Group A had significantly larger maximum and 1st percentile R-R shortening and lengthening compared with Group H and Group O during the recovery phase where most arrhythmias were observed. During recovery, a cutoff of 6% maximum % R-R shortening predicted the presence of arrhythmia with 88% sensitivity and 97% specificity and likelihood ratio of 26. CONCLUSIONS AND CLINICAL IMPORTANCE: Healthy horses have little instantaneous R-R variation during exercise. If a cardiac cycle shortens more than 6% from the previous cycle during the recovery phase, this R-R interval is likely to represent an arrhythmic event.


Assuntos
Arritmias Cardíacas/veterinária , Teste de Esforço/veterinária , Frequência Cardíaca/fisiologia , Doenças dos Cavalos/diagnóstico , Animais , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatologia , Estudos de Casos e Controles , Feminino , Doenças dos Cavalos/fisiopatologia , Cavalos/fisiologia , Masculino
20.
J Vet Cardiol ; 22: 2-19, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30559056

RESUMO

The sinoatrial node (SAN) is the primary pacemaker in canine and human hearts. The SAN in both species has a unique three-dimensional heterogeneous structure characterized by small pacemaker myocytes enmeshed within fibrotic strands, which partially insulate the cells from aberrant atrial activation. The SAN pacemaker tissue expresses a unique signature of proteins and receptors that mediate SAN automaticity, ion channel currents, and cell-to-cell communication, which are predominantly similar in both species. Recent intramural optical mapping, integrated with structural and molecular studies, has revealed the existence of up to five specialized SAN conduction pathways that preferentially conduct electrical activation to atrial tissues. The intrinsic heart rate, intranodal leading pacemaker shifts, and changes in conduction in response to physiological and pathophysiological stimuli are similar. Structural and/or functional impairments due to cardiac diseases including heart failure cause SAN dysfunctions (SNDs) in both species. These dysfunctions are usually manifested as severe bradycardia, tachy-brady arrhythmias, and conduction abnormalities including exit block and SAN reentry, which could lead to atrial tachycardia and fibrillation, cardiac arrest, and heart failure. Pharmaceutical drugs and implantable pacemakers are only partially successful in managing SNDs, emphasizing a critical need to develop targeted mechanism-based therapies to treat SNDs. Because several structural and functional characteristics are similar between the canine and human SAN, research in these species may be mutually beneficial for developing novel treatment approaches. This review describes structural, functional, and molecular similarities and differences between the canine and human SAN, with special emphasis on arrhythmias and unique causal mechanisms of SND in diseased hearts.


Assuntos
Arritmias Cardíacas/veterinária , Cães/anatomia & histologia , Sistema de Condução Cardíaco/fisiologia , Nó Sinoatrial/anatomia & histologia , Animais , Arritmias Cardíacas/fisiopatologia , Doenças do Cão/fisiopatologia , Humanos , Nó Sinoatrial/fisiologia , Nó Sinoatrial/fisiopatologia
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