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1.
Factors Affecting Prognosis and Conversion in Equine Atrial Fibrillation   总被引：4，自引：0，他引：4  
Sixty-seven horses presented with atrial fibrillation (AF) from January 1, 1980 to August 1, 1986. All horses were evaluated for the type and severity of the underlying cardiac disease and the probable duration of the arrhythmia. Fifty-two (78%) of the horses were treated with quinidine sulfate and/or digoxin. The response to treatment was assessed in each horse. Horses were followed for periods extending from 8 months to 7 years. Standardbreds, young horses, and males predominated in the study group. There were more male horses (stallions and geldings) than mares. Most horses with AF had no evidence of other cardiac disease (56.7%). All performance horses without other cardiac disease were treated, and return to performance was significantly associated with conversion to sinus rhythm. Horses that did not convert with quinidine sulfate therapy, whose arrhythmia recurred, and that had side effects from quinidine sulfate therapy, had a longer history of poor performance. Tachycardia (heart rate greater than 60 beats/min) was significantly associated with the existence of congestive heart failure. The horses with congestive heart failure had a poor prognosis for life (7.7% survived) and a poor conversion to normal sinus rhythm (23.1%). Mitral regurgitation (19 horses) was the most common underlying cardiac disease. Tricuspid regurgitation (15 horses), aortic regurgitation (3 horses), myocardial dysfunction (3 horses), and atrial septal defect (1 horse) also were diagnosed. Congestive heart failure was common in this group of horses with underlying cardiac disease.  相似文献   

2.
REASONS FOR PERFORMING STUDY: It has been reported that i.v. flecainide has a high efficacy for the treatment of experimentally-induced acute atrial fibrillation (AF) in horses and that its use is associated with minimal toxic side effects. OBJECTIVES: The objectives were to study the efficacy of i.v. flecainide as a treatment for atrial fibrillation in horses with naturally-occurring AF. METHODS: Ten horses with naturally-occurring AF were treated with 2 mg/kg bwt flecainide i.v. at a rate of 0.2 mg/kg bwt/min. In 3 horses, the infusion was continued at 0.05-0.10 mg/kg bwt/min until a total dose of 3.0 mg/kg bwt had been administered. Heart rate, QRS duration and average interval between fibrillation waves were measured before, during and following flecainide infusion. If conversion to normal sinus rhythm was not achieved, horses were treated with quinidine sulphate per os at a dose of 22 mg/kg bwt given every 2 h. RESULTS: None of the horses with chronic AF (n = 9) converted to sinus rhythm with flecainide i.v. The only horse treated successfully had acute AF of 12 days' duration. The QRS duration and fibrillation cycle length increased significantly (P = 0.006 and 0.002, respectively) during and following flecainide infusion. Heart rate did not increase significantly over time however, 3 horses developed heart rates in excess of 100 beats/min. Two horses developed a potentially dangerous ventricular dysrhythmia during the first 15 mins of treatment. Quinidine sulphate given per os restored sinus rhythm in 8 out of 9 horses, with minimal adverse effects. CONCLUSIONS: Although flecainide might be efficacious in cases of acute AF, it was not possible to restore sinus rhythm in horses with naturally-occurring chronic AF at the dosages used in this study. In 2 horses, 2.0 mg/kg bwt flecainide was associated with potentially dangerous dysrhythmias. POTENTIAL CLINICAL RELEVANCE: Intravenous administration of 2 mg/kg bwt flecainide is unlikely to convert chronic AF in horses and could induce dangerous dysrhythmias.  相似文献   

3.
Quinidine is effective for treatment of atrial fibrillation (AF) in horses, but often accelerates ventricular response rate. Diltiazem effectively controls heart rate response to AF in other species. This investigation determined the effects of diltiazem on cardiac rate and rhythm, left ventricular (LV) function, central hemodynamics, and peripheral blood flow in normal, standing, nonsedated horses. A dose-finding study was performed. Afterward, 8 healthy horses were treated with diltiazem IV every 30 minutes to achieve cumulative dosages of 0 (saline control), 1, 1.5, and 2 mg/kg. Plasma diltiazem concentration, heart rate and rhythm (by electrocardiography), LV function and central hemodynamics (by cardiac catheterization), LV dimensions (by echocardiography), and forelimb blood flow (by Doppler sonography) were determined during each treatment period. Diltiazem plasma concentrations between 390 and 910 ng/mL were achieved, with considerable variation among horses. Cardiac effects of diltiazem included intermittent depression of the sinus and atrioventricular (AV) nodes and mild impairment of systolic and diastolic LV function. Vascular effects of diltiazem included arterial vasodilatation, increased limb blood flow, and decreased systemic vascular resistance. Baroreceptor reflex-mediated sympathetic activation increased sinus node rate and presumably blunted the depressive effects of diltiazem on myocardial and nodal tissues. Two horses developed transient high-grade sinus arrest with severe systemic hypotension. Diltiazem appears relatively safe in healthy horses, but dosage may be limited by hypotension from vasodilatation and direct suppression of sinus node discharge. Because of its inhibitory effects on AV nodal conduction, diltiazem may prove useful for heart rate control in horses with AF.  相似文献   

4.
BACKGROUND: Lidocaine is most frequently used to treat ventricular arrhythmias. However, lidocaine may have an antiarrhythmic effect for certain supraventricular arrhythmias. HYPOTHESIS: We hypothesized that lidocaine would be effective in converting experimentally induced atrial fibrillation (AF) to sinus rhythm and that a decrease in the dominant frequency (DF) and an increase in the organization as judged by the spectral entropy (SE) would occur over the course of the conversion. ANIMALS: Seven German Shepherd (GS) Dogs. METHODS: Dogs were anesthetized with fentanyl and pentobarbital. AF was induced with standard pacing protocols while left and right atrial monophasic action potentials (MAP) were recorded. The power spectra from the MAP recordings were analyzed to determine DF and SE during treatment with boluses of 2 mg/kg lidocaine. RESULTS: Lidocaine converted AF to sinus rhythm in all dogs and all episodes (n = 19). Conversion time was 27-87 seconds. After atropine, sustained AF was not induced; however, 5 episodes of atrial tachycardia resulted, and 3 were converted with lidocaine. Frequency domain analysis of 12 conversion sequences showed that left and right DF of the MAP signals decreased from the time of injection to conversion to sinus rhythm (P < .001). Mean SE indicated a gradient between the left and right atria (P = .003) that did not change during conversion. CONCLUSIONS AND CLINICAL IMPORTANCE: Vagally associated AF in GS dogs is terminated with lidocaine. Lidocaine is likely an effective treatment in clinical dogs with vagally associated AF.  相似文献   

5.
Diagnosis and treatment of cardiac arrhythmias   总被引：1，自引：0，他引：1  
Cardiac arrhythmias are probably more common in horses than in any other domestic animal species. The most frequent clinical complaint associated with cardiac arrhythmias is exercise intolerance. Physical examination is characterized by auscultation abnormalities such as fast or slow heart rate, irregular rhythm, extra sounds, long pauses, or abnormal heart sounds. The electrocardiogram is used to make a definitive diagnosis of the dysrhythmia. Other laboratory and cardiac function tests are employed to determine the etiology and to assess the significance of the arrhythmia. Antiarrhythmic therapy is given when clinical signs specifically related to the arrhythmia are present, when hemodynamic parameters are compromised by the arrhythmia, or when the ECG reveals abnormalities that put the patient at risk for development of more severe arrhythmias. The cardiovascular drugs most frequently used are digoxin and quinidine. Digoxin is most commonly used for supraventricular arrhythmias, especially arrhythmias characterized by fast heart rates. Quinidine is very effective for short-term treatment of ventricular and supraventricular arrhythmias but must be used with caution because of the potential for toxic side effects. The cardiac arrhythmias due to vagal tone (sinus arrhythmia, sinus block, sinus arrest, sinus bradycardia, wandering pacemaker, first-degree AV block, and second-degree AV block) that are found in resting horses are generally considered to be normal and generally do not require therapy.  相似文献   

6.
OBJECTIVE: To determine signalment, clinical signs, diagnostic findings, treatment, and outcome for cats with atrial fibrillation (AF). DESIGN: Retrospective study. ANIMALS: 50 cats. PROCEDURE: Medical records of cats that met criteria for a diagnosis of AF (ECG consisting of at least 2 leads, clear absence of P waves, supraventricular rhythm, and convincingly irregularly irregular rhythm) and had undergone echocardiography were reviewed. RESULTS: There were 41 males (37 castrated) and 9 females (7 spayed). Forty-one were of mixed breeding; 9 were purebred. Mean +/- SD age was 10.2 +/- 3.7 years. The most common chief complaints were dyspnea, aortic thromboembolism, and lethargy. In 11 cats, AF was an incidental finding. Mean +/- SD ventricular rate was 223 +/- 36 beats/min. The most common echocardiographic abnormalities were restrictive or unclassified cardiomyopathy (n = 19), concentric left ventricular hypertrophy (18), and dilated cardiomyopathy (6). Mean +/- SD left atrial-to-aortic diameter ratio (n = 39) was 2.55 +/- 0.80. The most common thoracic radiographic findings were cardiomegaly, pleural effusion, and pulmonary edema. Median survival time (n = 24) was 165 days (range, 0 to 1,095 days). Eight of 24 cats lived for > or = 1 year after a diagnosis of AF was made. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that AF occurs primarily in older adult male cats with structural heart disease severe enough to lead to atrial enlargement. Atrial fibrillation in these cats was most commonly first detected when signs of decompensated cardiac disease were evident, but also was commonly identified as an incidental finding.  相似文献   

7.
A 12-year-old spayed female German shorthaired pointer dog sustained extensive bite wounds around the neck. At presentation, atrial fibrillation was identified with a rapid ventricular response rate of 300 beats per minute (bpm). The ventricular response rate rapidly decreased to 130 bpm following administration of hydromorphone and oxygen. Based on the rate, antiarrhythmic therapy was not initiated. The heart rhythm converted back to sinus rhythm by the time of the first recheck evaluation 2 days later, and the dog remained in sinus rhythm at all subsequent evaluations. With the resolution of the arrhythmia, paroxysmal atrial fibrillation was suspected. The underlying etiology of the arrhythmia was not determined; however, imbalances in autonomic tone associated with trauma and/or direct trauma to the heart were hypothesized.Key clinical message:This report indicates a possible role of imbalances in autonomic tone due to trauma in the development of paroxysmal atrial fibrillation and suggests that it should be a differential diagnostic consideration in patients with atrial fibrillation following trauma. Primary treatment of atrial fibrillation may not be needed in these cases if the ventricular response rate is not rapid, or if there is spontaneous conversion to sinus rhythm.  相似文献   

8.
Intravenous administration of quinidine gluconate converted atrial fibrillation (AF) to sinus rhythm in 9 of 12 horses. Twelve horses that were diagnosed by ECG to have AF were administered up to 11 mg of quinidine gluconate/kg of body weight in 1.0- to 1.5-mg/kg bolus injections every 10 to 15 minutes. The total dose of quinidine administered IV ranged from 1.8 to 5.8 g. Increased ventricular rate, apprehension, and mild depression were observed during treatment. Other signs of toxicosis were not observed. One horse was successfully treated with IV administered quinidine gluconate on 3 occasions. Intravenous administration of quinidine is a safe and effective alternative for treatment of AF in some horses.  相似文献   

9.
BACKGROUND: Atrial fibrillation (AF) in dogs can be managed by electrical cardioversion to sinus rhythm, but early recurrence of AF occurs in some dogs. In humans, the commonly evaluated clinical variables for prediction of early relapse of AF are left atrial size and duration of AF. It is unclear whether the duration of AF affects maintenance of sinus rhythm after cardioversion in dogs with spontaneous AF. HYPOTHESIS: That duration of sinus rhythm after cardioversion is related to the chronicity of AF. ANIMALS: Forty-one consecutive dogs that had undergone successful transthoracic cardioversion for spontaneous AF were evaluated. METHODS: The relationship between the duration of documented AF and the duration of sinus rhythm after cardioversion was statistically evaluated using data obtained retrospectively. The effects of structural heart disease and pretreatment with amiodarone were also evaluated. RESULTS: The presence of structural heart disease and the duration of documented AF had significant effects on maintenance of sinus rhythm after cardioversion (P <.001 and P=.022, respectively). The duration of documented AF was inversely related to the duration of sinus rhythm (P=.022) in dogs with and without structural heart disease. CONCLUSIONS AND CLINICAL IMPORTANCE: Estimates of duration of sinus rhythm based on the duration of documented AF are provided for dogs with and without heart disease allowing prediction of risk for early AF relapse.  相似文献   

10.
A six‐year‐old female spayed mixed‐breed dog was referred following a 3‐week history of lameness and progressive neurological deficits in both hindlimbs, and a 1‐week history of a cardiac arrhythmia. The dog was diagnosed with hypothyroidism, atrial fibrillation, myocardial dysfunction and arterial thromboembolism. Cardioversion occurred after 2 weeks of levothyroxine supplementation, with improved systolic function over time. To the authors’ knowledge, this is the first case reported in the veterinary or human literature documenting hypothyroidism with persistent atrial fibrillation being converted to sinus rhythm with levothyroxine as sole therapy.  相似文献   

11.
BACKGROUND: Transvenous electrical cardioversion (TVEC) has been developed for treatment of atrial fibrillation (AF) in horses. The relationship among patient variables, treatment response, and outcome in a typical referral population has not been evaluated. HYPOTHESIS: Patient variables such as age, sex, weight, and duration of arrhythmia affect prognosis for response to treatment and the energy level at which cardioversion occurs. ANIMALS: TVEC was applied to 72 episodes of lone AF in 63 client-owned performance horses, with the majority (54) being Standardbred racehorses. METHODS: Catheterization of the right atrium (RA) and pulmonary artery (PA) through the jugular vein was used for electrode placement before horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energy levels until cardioversion was achieved or a maximum single-energy level of 300 J was reached (cumulative energy 50-1,960 J). A multivariate model was constructed to evaluate influence of patient factors on cardioversion energy. RESULTS: Cardioversion was achieved in 71 of 72 episodes (62 of 63 horses) at a mean energy of 165.43 +/- 8.75 J. Cardioversion energy was higher for females than for males, and for interaction terms, weight was negatively related to energy in females and positively related in males. Age was positively related to cardioversion energy in females. No relationship was identified between duration of arrhythmia before treatment and prognosis for response or cardioversion energy. CONCLUSIONS AND CLINICAL IMPORTANCE: TVEC is highly effective in the treatment of lone AF in horses. Although age and sex influence cardioversion energy level, duration of arrhythmia does not.  相似文献   

12.
Objective: The purpose of this study was to examine a population of miniature schnauzers exhibiting syncope as their primary presenting complaint and to correlate their electrocardiographic (ECG) findings with the criteria for the diagnosis of sick sinus syndrome (SSS) reported in the human and veterinary literature. Design: Retrospective study. Patients: Case records of 31 miniature schnauzers with syncope during the period 1996–2000 were reviewed. Measurements and results: This study supported two previous studies finding that females were more predisposed to ECG abnormalities associated with SSS than males. It was also noted that females were slightly older (10.1 years) when compared to males (8.9 years) at the time of diagnosis. A heart murmur was present in 61% of the dogs and this was most likely secondary to mitral valve endocardiosis and regurgitation. The primary rhythm disturbance seen was sinus arrest/sinoatrial block in 48.5% of the cases; sinus bradycardia was the second most common arrhythmia noted. Conclusion: In miniature schnauzers with syncope, SSS should be considered as a primary etiology if abnormal ECG findings are noted.  相似文献   

13.
Sustained narrow-QRS tachycardia of three months duration and left ventricular systolic dysfunction were identified in a fifteen-year-old Quarter Horse. No underlying cause for the tachyarrhythmia was found and no predisposing structural cardiac lesions were evident by echocardiography. Intravenous diltiazem and lidocaine were administered without achieving successful conversion of the arrhythmia. Oral quinidine therapy converted the tachyarrhythmia to sinus rhythm. Ventricular systolic dysfunction and chamber dilatation subsequently resolved. As with other species, echocardiographic features of dilated cardiomyopathy can be tachycardia-induced and may resolve following successful control of heart rate and rhythm.  相似文献   

14.
Two dogs with acute onset atrial fibrillation (AF) were cardioverted to sinus rhythm by the administration of 2 mg/kg lidocaine given intravenously. Each dog was believed to have AF initiated because of elevated vagal tone. This report has potential clinical impact for a subset of dogs because it offers a treatment to circumvent persistent AF. Furthermore, this encouraging result of a pharmacologic cardioversion suggests that further investigation would be of interest to ascertain the effectiveness and mechanism of the antiarrhythmic action of lidocaine in vagally induced AF.  相似文献   

15.
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16.
Atrial fibrillation is a common arrhythmia in dogs with structural cardiac disease and can result in significant clinical signs. Several methods of electrical cardioversion of atrial fibrillation have been described. Biphasic transthoracic cardioversion of atrial fibrillation in dogs with naturally occurring heart disease has been described in veterinary medicine and has been shown to be highly successful. In humans and research animals intracardiac and transesophageal cardioversion of atrial fibrillation has been described as an alternative to transthoracic cardioversion. While transesophageal cardioversion is very successful in humans and research animals, this technique has not been previously described in a clinical patient with naturally occurring heart disease in veterinary medicine. This report describes the use of transesophageal cardioversion in a dog with atrial fibrillation and structural cardiac disease. Cardioversion was unsuccessful using two electrodes positioned within the esophagus. Cardioversion of atrial fibrillation to normal sinus rhythm was successfully achieved and maintained using one electrode positioned within the esophagus and one electrode positioned within the right atrium using a synchronized monophasic shock of 50 J.  相似文献   

17.
Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.  相似文献   

18.
IntroductionHyperthyroidism is a predisposing factor for atrial fibrillation (AF) in humans. The relationship between high thyroid hormone (TH) and AF in horses has not been evaluated.ObjectivesThe aim of this study is to identify whether (1) high TH concentrations were present in horses with AF, (2) other cardiovascular effects were observed in horses with high TH and AF, and (3) TH status affected recurrence rate.AnimalsTwenty-three horses presented with naturally occurring AF.MethodsProspective case–control clinical study. Thyroid hormone concentration was measured in horses presenting with AF. Heart rate, electrocardiogram, blood pressure, and an echocardiogram were recorded as part of their clinical workup. Recurrence rate was determined by owner/veterinarian follow-up.ResultsHigh TH concentration was found in 60% of horses with AF. Horses in the high TH group had a higher heart rate (P=0.001), systolic blood pressure (P=0.019), left ventricular free wall thickness (P=0.026), relative wall thickness (P=0.041) and were more likely to have periods of AF with a rapid ventricular response rate (P=0.022). All horses were successfully converted to normal sinus rhythm. The likelihood of recurrence was not different between groups.ConclusionElevated TH concentration can be found in horses with AF. Other cardiovascular effects of high TH concentrations in other species were also present in horses with AF and elevated TH concentrations. This study recommends measuring TH concentrations in horses presenting for AF with a history of thyroid or iodine supplementation. This study also cautions against TH or iodine supplementation in healthy performance horses.  相似文献   

19.
Objective – To review the human and veterinary literature on the pathophysiology of myasthenia gravis (MG) and describe treatment options for clinical use in people and animals. Data Sources – Human and veterinary clinical reports, studies and reviews, textbooks, and recent research findings in MG from 1996 present, with a focus on treatment and patient management. Human Data Synthesis – MG is a well‐described condition in people with new research and treatment options available. Many of the newest therapeutic options available in veterinary medicine for MG are based on current strategies used in people with this condition. Seronegative MG is well described in people and provides insight to clinical cases encountered in veterinary medicine when the index of suspicion is high though serologic tests are negative. Veterinary Data Synthesis – Previous studies in veterinary medicine focused on the use of acetylcholinesterase inhibitors as the main form of treatment in canine MG. Recent studies, mainly case series and case reports, emphasize the use of immunomodulatory treatments as an alternative for long‐term treatment. However, there are no randomized, controlled studies on treatment with immunomodulatory therapy for MG in dogs available to assess the efficacy of this treatment strategy. Conclusions – Although early recognition of clinical signs is most important in the outcome of patients with MG, further understanding the pathophysiology of MG may lead to earlier diagnosis and novel treatment strategies. The discovery of additional autoantibodies against striated muscle proteins in dogs, should enhance our understanding of diseases affecting the neuromuscular junction. In addition, clinical data for canine MG could be applied to other autoimmune disorders.  相似文献   

20.
药物晶型不仅影响药物稳定性和生产、制剂工艺的可操作性,也影响药物的溶解度、溶出速率,进而影响到药物的生物利用度和有效性。因此,对晶型药物质量控制和管理的研究,是在兽药领域中非常重要的课题之一。本文晶型药物研究的效应、研究方法,并对晶型药物在兽药中的应用前景进行综合分析和讨论,以期对晶型兽药的研究和管理提供参考。  相似文献   

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