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1.
Vet J ; 272: 105651, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33745806

RESUMEN

Sinus arrhythmia of the dog is unique because of the pronounced alternating beat-to-beat intervals. The clustering of these short (faster rates) and long (slower rates) intervals is not just influenced by autonomic input from breathing; sinus arrhythmia can persist in the panting or apneic dog. The multiplicity of central and peripheral influences on the sinus node complicates the unraveling of the mechanisms of sinus arrhythmia. Studies of the sinus node suggest that acetylcholine can slow cellular depolarization and block sinoatrial conduction. Electrocardiographic monitoring of the dog supports this notion in that abrupt bifurcation into short and long intervals develop at lower heart rates. We sought to determine whether this phenomenon could be recapitulated in canine atrial preparations perfused with acetylcholine and whether selective pharmacologic blockade of the voltage and calcium clocks could provide insight into its mechanism. Spontaneous beat to beat (A-A) intervals were obtained from monophasic action potential recordings of perfused canine right atrial preparations before and during perfusion with acetylcholine (2-5 µM). The calcium clock was blocked with ryanodine (2-3 µM). The membrane clock was blocked with diltiazem hydrochloride (ICa,L blocker; 0.25 µM) and ZD7288 (If blocker; 3 µM). Hyperpolarization was hindered by blockade of IK,Ado/IK,Ach with tertiapin Q (100 nM) before and during acetylcholine perfusion. Acetylcholine resulted in beat clusters similar to those seen in sinus arrhythmia of the dog. Beat clusters were consistent with intermittent 2:1 and 3:1 sinoatrial conduction block. Tertiapin Q abolished this patterning suggesting a role of IK,Ado/IK,ACh in the mechanism of these acetylcholine-induced beat-to-beat patterns.


Asunto(s)
Acetilcolina/administración & dosificación , Arritmia Sinusal/veterinaria , Enfermedades de los Perros/fisiopatología , Atrios Cardíacos/efectos de los fármacos , Bloqueo Cardíaco/veterinaria , Nodo Sinoatrial/fisiopatología , Animales , Arritmia Sinusal/fisiopatología , Perros , Electrocardiografía/veterinaria , Atrios Cardíacos/fisiopatología , Bloqueo Cardíaco/inducido químicamente , Bloqueo Cardíaco/fisiopatología , Frecuencia Cardíaca/efectos de los fármacos
2.
Vet J ; 270: 105624, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33641808

RESUMEN

Pacemakers use heart rate histograms (% beats) and sensor indicated rate histograms (% time) to illustrate rate distributions. When programmed to the rate adaptive modes, these data are used to determine the appropriateness of rate response to activity. These histograms are generated from instantaneous heart rate calculations. In humans, such data are compared to known histographic rate profiles. Such rate profiles during 24 h in the dog are not available. Moreover, data representation differ between Holter monitoring and pacemakers making comparisons challenging. The rate distribution in dogs >7-years of age was determined over 24 h using instantaneous and rolling average heart rate. Such data could serve as a guide to programming pacing rates for dogs. Sinus arrhythmia resulted in dissimilar heart rate profiles depending on the method of determining rate. The long intervals of sinus arrhythmia resulted in median values for the percent of time with an instantaneous heart rate of <50 beats/min (bpm) of 15%, whereas a rolling average heart rate of <50 bpm was 0.2%. Based on the cumulative time of the rolling average rate, dogs spent 26.3% of the day between 70-90 bpm with rates <65 bpm and >90 bpm approximating 30% for each. Rates >160 bpm were uncommon (<1%). However, high variability existed between dogs. This study demonstrated the shortcomings of both instantaneous and averaging methods to evaluate heart rate profiles in the dog and that both methods should be incorporated when making pacing rate decisions during programming.


Asunto(s)
Arritmias Cardíacas/veterinaria , Enfermedades de los Perros/fisiopatología , Determinación de la Frecuencia Cardíaca/veterinaria , Frecuencia Cardíaca/fisiología , Marcapaso Artificial/veterinaria , Programas Informáticos , Factores de Edad , Animales , Arritmia Sinusal/fisiopatología , Arritmia Sinusal/veterinaria , Arritmias Cardíacas/fisiopatología , Arritmias Cardíacas/terapia , Enfermedades de los Perros/terapia , Perros , Electrocardiografía Ambulatoria/veterinaria , Femenino , Determinación de la Frecuencia Cardíaca/métodos , Humanos , Masculino , Valores de Referencia , Síndrome del Seno Enfermo/fisiopatología , Síndrome del Seno Enfermo/terapia , Síndrome del Seno Enfermo/veterinaria , Programas Informáticos/estadística & datos numéricos
5.
Pesqui. vet. bras ; 36(6): 551-558, jun. 2016. tab, ilus
Artículo en Inglés | LILACS, VETINDEX | ID: lil-792606

RESUMEN

The veterinary cardiology has growing importance in equine medicine. There are studies of standardization of electrocardiographic parameters of many races, according to their stature and ability. However, no studies are in the literature with the American Miniature Horse. To evaluate the electrocardiogram (ECG) tracing configuration of this breed at rest and to verify the influence of age and sex on ECG parameters, 203 horses including 143 females and 60 males were divided into four age groups (foals, yearlings, adults and elderly). Electrocardiographic parameters were performed by computerized electrocardiogram (TEB), and the parameters were evaluated in six leads of frontal plane (Lead I, II, III, aVR, aVL and aVF) and base-apex (BA). Heart rates (HR) decreased with increasing age were higher in males than in females. Sinus tachycardia followed by sinus arrhythmia was dominant in both sexes. The cardiac axis was higher in males and ranged between 120° and 150° for foals, 30° and 60° for yearlings and adults, and 60° and 90° for the elderly. The P wave was bifid in several animals. The P-wave amplitude and T-wave duration from lead II and BA were larger in males than in females. The majority of the animals exhibited ST segment depression and a negative T-wave. The most common QRS complex morphology was Qr. Differences were observed between the electrocardiographic tracings of males and females, and age influenced the ECG parameters. Therefore, this study established the ECG patterns for the American Miniature Horse breed and could be used to determine the influence of age and sex on several of the studied variables.(AU)


A cardiologia veterinária possui crescente importância na medicina equina. Existem estudos de padronização dos parâmetros eletrocardiográficos de muitas raças, de acordo com sua estatura e aptidão. No entanto, não há na literatura trabalhos com os equinos da raça Miniature Horse. Os objetivos deste trabalho foram avaliar a configuração do traçado do eletrocardiograma (ECG) em repouso, de equinos desta raça, além de verificar a influência do sexo e da idade sobre os parâmetros eletrocardiográficos desses animais. Foram utilizados 203 equinos desta raça, hígidos, sendo 143 fêmeas e 60 machos, classificados em quatro faixas etárias (potros, sobreanos, adultos e idosos). Os exames eletrocardiográficos foram realizados por eletrocardiograma computadorizado (TEB), e os parâmetros foram avaliados em seis derivações do plano frontal (DI, DII, DIII, aVR, aVL e aVF) e base-ápice (BA). A frequência cardíaca (FC) diminuiu com a progressão da idade, e foi maior nos machos do que nas fêmeas. O ritmo mais comum em ambos os sexos foi taquicardia sinusal, seguido de arritmia sinusal. O eixo cardíaco foi maior nos machos do que nas fêmeas, e nos potros ficou entre 120 e 150o, nos sobreano e adultos permaneceu entre 30 e 60o, e nos idosos entre 60 e 90o. A amplitude da onda P e a duração da onda T foram maiores nos machos do que nas fêmeas na DII e BA. A maioria dos animais apresentou segmento ST infradesnivelado e onda T negativa. A morfologia do complexo QRS mais encontrada em todos os casos foi Qr. Este estudo permitiu estabelecer os padrões eletrocardiográficos para a raça Mini Horse e conseguiu verificar a influência da progressão da idade nas diversas variáveis estudadas, bem como a diferença entre os sexos.(AU)


Asunto(s)
Animales , Arritmia Sinusal/veterinaria , Electrocardiografía/veterinaria , Caballos , Taquicardia Sinusal/veterinaria , Técnicas de Diagnóstico Cardiovascular/veterinaria , Frecuencia Cardíaca , Estándares de Referencia
6.
Pesqui. vet. bras ; 36(2): 90-93, fev. 2016. graf
Artículo en Inglés | LILACS | ID: lil-777393

RESUMEN

Pre-operative electrocardiograms performed in 700 dogs were analyzed in order to establish correlation between sex, age, indication for surgery, body condition score, breed and weight. Initially a clinical questionnaire was filled out from each owner, including age, breed, sex, weight, clinical history and surgical indication. Dogs above 6 years of age or those showing any kind of cardiac auscultation disturbances were referred to electrocardiogram (ECG) evaluation. All ECG were performed and analyzed by the same veterinary specialist. Abnormalities at ECG were founnd in 364 of 700 (52%) evaluated dogs, and the most frequent variation was sinus arrhythmia, observed in 293 dogs (25.4%). No significant correlation was found between the electrocardiographic alterations with weight, sex and age of the animals. Therefore ECG should be conducted routinely regardless of age, sex, breed or surgical indication, highlighting its value for determining a safe anesthetic protocol that promotes minimal cardiopulmonary depression and allows rapid post-surgical recovery.


Foram analisados exames eletrocardiográficos pré-operatórios de 700 cães, com o objetivo de estabelecer correlação entre sexo, idade, indicação cirúrgica, condição corporal, raça e peso. Inicialmente, um questionário clínico foi preenchido por cada proprietário, com informações sobre sexo, raça, sexo, peso, histórico clínico e indicação cirúrgica. Os cães com mais de seis anos de idade e aqueles que apresentavam qualquer tipo de alteração à auscultação cardíaca foram encaminhadas para avaliação por meio de eletrocardiograma (ECG). Todos os ECG foram realizados e analisados pelo mesmo veterinário especialista. As anormalidades ao ECG foram observadas em 364 dos 700 (52%) cães avaliados e a alteração mais frequente foi a arritmia sinusal, observada em 293 (25,4%) cães. Nenhuma correlação significante foi observada entre as alterações eletrocardiográficas com o peso, o sexo e a idade dos animais. Sugere-se, portanto que o exame de ECG seja realizado de forma rotineira, independente de idade, sexo, raça ou indicação cirúrgica, destacando seu valor para a determinação de um protocolo anestésico que promova mínima depressão cardiopulmonar e rápida recuperação pós-cirúrgica.


Asunto(s)
Animales , Perros , Anestesia/veterinaria , Arritmia Sinusal/veterinaria , Electrocardiografía , Procedimientos Quirúrgicos Operativos/veterinaria , Arritmias Cardíacas/veterinaria , Electrocardiografía/veterinaria
7.
J Vet Cardiol ; 18(1): 1-9, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26795971

RESUMEN

OBJECTIVES: To document the electrocardiographic findings of vagally-induced paroxysmal atrial fibrillation following a presumed reflex syncopal episode in the dog. ANIMALS: Seven dogs with a syncopal episode followed by a paroxysm of atrial fibrillation recorded on a 24-hour Holter. METHODS: Twenty-four hour Holter monitors were retrospectively reviewed, analysing the cardiac rhythm associated with syncopal events. Each recording was analysed from 10 min before the syncopal episode to until 10 min after a normal sinus rhythm had returned. RESULTS: Nine episodes were recorded in seven dogs, with one patient experiencing three events during one Holter recording. Five of the seven dogs presented with underlying structural heart disease. In two the syncopal episodes occurred following exercise, two associated with coughing and three were during a period of rest. All dogs had documented on the Holter recording a rhythm abnormality during syncope. The most common finding leading up to the syncopal event was development of a progressive sinus bradycardia, followed by sinus arrest interrupted by a ventricular escape rhythm and then ventricular arrest. This was then followed by an atrial fibrillation. The atrial fibrillation was paroxysmal in seven recordings and persistent in two. In two dogs, the atrial fibrillation reorganised into self-limiting runs of atypical atrial flutter. CONCLUSIONS: This combination of electrocardiographic arrhythmias are probably caused by an inappropriate parasympathetic stimulation initiating a reflex or neurally-mediated syncope, with abnormal automaticity of the sinus node and of the subsidiary pacemaker cells and changes in the electrophysiological properties of the atrial muscle, which promoted the paroxysmal atrial fibrillation.


Asunto(s)
Fibrilación Atrial/veterinaria , Enfermedades de los Perros/fisiopatología , Síncope/veterinaria , Animales , Arritmia Sinusal/veterinaria , Fibrilación Atrial/fisiopatología , Perros , Electrocardiografía/veterinaria , Femenino , Masculino , Estudios Retrospectivos , Síncope/fisiopatología
11.
J Vet Cardiol ; 12(3): 191-6, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21036115

RESUMEN

The RR intervals of sinus and ventricular beats were determined by analysis of a 24-h ambulatory electrocardiogram in a Boxer before and after treatment with sotalol. These RR intervals were plotted using tachograms, histograms, and Poincaré plots. The tachogram demonstrated a 'band' wherein a range of RR intervals was infrequent, the histogram did not take the form of a single Gaussian distribution of RR intervals, and the Poincaré plot showed nonhomogeneous beat-to-beat variability. This type of patterning was described as a "zone of avoidance" potentially caused by the clustering of beats within specific ranges. Treatment with sotalol enhanced the "zone of avoidance". Further investigation is needed to understand the mechanism for this observation as well as any clinical implications.


Asunto(s)
Arritmia Sinusal/veterinaria , Enfermedades de los Perros/fisiopatología , Animales , Antiarrítmicos/uso terapéutico , Arritmia Sinusal/diagnóstico , Arritmia Sinusal/tratamiento farmacológico , Arritmia Sinusal/fisiopatología , Enfermedades de los Perros/diagnóstico , Enfermedades de los Perros/tratamiento farmacológico , Perros , Electrocardiografía Ambulatoria/veterinaria , Femenino , Sotalol/uso terapéutico
17.
J Vet Cardiol ; 9(2): 135-7, 2007 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-18229428

RESUMEN

A Labrador retriever, presented for a routine yearly wellness exam, shows on ECG a normal sinus rhythm with first degree atrioventricular blockade and atrial dissociation (AD). A detailed cardiologic examination was performed including thoracic radiography, echocardiography and blood pressure measurement, all of which were considered normal. The dog described in this current report was re-examined several times over the subsequent 2 years and no clinical signs of heart failure, heart disease or other diseases were recognized, the AD appears to have been benign.


Asunto(s)
Arritmia Sinusal/veterinaria , Bloqueo Atrioventricular/veterinaria , Enfermedades de los Perros/diagnóstico , Animales , Arritmia Sinusal/diagnóstico , Arritmia Sinusal/fisiopatología , Bloqueo Atrioventricular/diagnóstico , Bloqueo Atrioventricular/fisiopatología , Enfermedades de los Perros/fisiopatología , Perros , Electrocardiografía/veterinaria , Masculino
20.
Vet Rec ; 157(12): 341-3, 2005 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-16170001

RESUMEN

The electrocardiographic parameters of 40 healthy alpacas (Lama pacos) were recorded with a base-apex lead system to establish the normal resting electrocardiographic parameters in this species. The following parameters were measured: heart rate and rhythm, QRS and T morphology, ST segment position, P amplitude and duration, QRS duration and PQ and QT intervals. The heart rate varied between 50 and 110 bpm, with a mean (sd) of 80 (17.8) bpm, and no significant differences were observed between males and females or between alpacas of different ages. Sinus arrhythmia was observed in 35 of the animals, and a regular sinus rhythm was recorded in the other five. The QRS morphology was variable, with an 'rS' pattern observed in 29 animals, 'RS' in six, 'Rs' in three and 'QS' in the other two. A variable morphology was also observed for the T wave, which was positive in 27 animals, negative in seven and biphasic in the other six. All the electrocardiographic parameters were normally distributed and no significant differences were observed between the sexes, except that the amplitude of the P wave was higher in males. The PQ interval was significantly shorter in animals less than six months old.


Asunto(s)
Camélidos del Nuevo Mundo/fisiología , Electrocardiografía/veterinaria , Factores de Edad , Animales , Arritmia Sinusal/epidemiología , Arritmia Sinusal/veterinaria , Electrocardiografía/normas , Femenino , Frecuencia Cardíaca/fisiología , Masculino , Valores de Referencia , Factores Sexuales
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