Treatment of Atrial Fibrillation in Horses: New Perspectives

Reef, Virginia B.; Reimer, Johanna M.; Spencer, Pamela A.

doi:10.1111/j.1939-1676.1995.tb03274.x

Cited by 94 publications

(94 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, this substance has a number of side effects, including tachycardia and shock, which are independent of its concentration in the plasma. As a result, even the smallest dose is likely to induce grave side effects [13,16]. Flecainide, on the other hand, has shown few side effects other than those involving the heart.…”

Section: Discussionmentioning

confidence: 99%

Safe and Efficacious Dosage of Flecainide Acetate for Treating Equine Atrial Fibrillation.

Ohmura

Nukada

Mizuno

et al. 2000

The Journal of Veterinary Medical Science

View full text Add to dashboard Cite

ABSTRACT. To determine a safe and efficacious dose of flecainide acetate for treating equine atrial fibrillation (Af), the safe dosage level was determined by injecting 1, 2, or 3 mg/kg i.v. of 1% flecainide acetate solution at a rate of 0.2 mg/kg/min to five clinically healthy horses. Clinical signs and the ECG were monitored (HR, PR, QRS, and QT intervals) and blood was taken to measure the plasma flecainide concentration pre-and post-administration. No abnormal signs were observed in the 1-or 2-mg/kg groups, while agitation was observed in three of five horses in the 3-mg/kg group. The QRS, and QT intervals for the 3-mg/kg group increased significantly. The peak plasma flecainide concentrations were 1,316 ± 358 (SD) ng/ml, 1,904 ± 314 ng/ml, and 2,251 ± 387 ng/ml for the 1-, 2-, and 3-mg/kg groups, respectively. To evaluate the efficacy of flecainide, Af was induced by right atrial pacing in six clinically healthy horses, and 1% flecainide acetate solution was then administered until they converted to sinus rhythm. All horses with induced Af converted. For the conversion, a total dose of 1.40 ± 0.63 mg/kg flecainide was required, the duration of administration was 7.00 ± 3.15 min and plasma flecainide concentration at conversion was 1,303 ± 566 ng/ml. In conclusion, flecainide acetate is a safe and effective antiarrhythmic agent for equine Af, and the clinically effective dosage is 1 to 2 mg/kg. Atrial fibrillation (Af) is one of the most common arrhythmias encountered in horses. It is thought that treatment is necessary for Af that does not recover spontaneously [1,4]. There have been a number of reports on Af in horses. Most of these studies used quinidine for treatment [1,11,14]. However, quinidine is known to have a number of side effects, including nasal mucosal edema, dyspnea, diarrhea, colic, tachycardia and laminitis [6,9]. Successful treatment has not been reported using any drug other than quinidine [10]. It would be highly desirable to convert equine Af, using an antiarrhythmic agent with less severe side effects than quinidine.In humans, a wide variety of antiarrhythmic agents have been developed and clinically applied to Af. Flecainide is an antiarrhythmic agent of Vaughan-Williams class Ic, a different class than quinidine [7]. In humans, flecainide has been shown to be effective in treating both supraventricular and ventricular arrhythmias. The rate of cardioversion of paroxysmal Af exceeds 90%, which is higher than that for other antiarrhythmic agents [2,8]. With side effects seldom involving organs other than the heart, flecainide is a relatively safe drug [5]. Nonetheless, flecainide has not been tried in horses, nor has its ability to convert equine Af been evaluated.In this study, we examined the safety and effectiveness of flecainide acetate in treating induced Af in horses. The efficacious dosage and rate of administration of flecainide was determined using clinical observations, ECG, and measurement plasma flecainide concentrations as indicators of side effects. MATERIALS AND METHODSStu...

show abstract

Section: Discussionmentioning

confidence: 99%

Safe and Efficacious Dosage of Flecainide Acetate for Treating Equine Atrial Fibrillation.

Ohmura

Nukada

Mizuno

et al. 2000

The Journal of Veterinary Medical Science

View full text Add to dashboard Cite

show abstract

“…Atrial fibrillation is the most common clinically relevant arrhythmia affecting performance in athlete horses 5, 6, 7, 8. Orally administered quinidine sulfate is the pharmacologic treatment of choice for restoring SR in horses regardless of the duration of AF,9 and has a fairly high efficacy (65–90%) in horses with no underlying cardiac disease 8.…”

mentioning

confidence: 99%

Antiarrhythmic and Electrophysiologic Effects of Flecainide on Acutely Induced Atrial Fibrillation in Healthy Horses

Haugaard

Pehrson

Carstensen

et al. 2014

Veterinary Internal Medicne

View full text Add to dashboard Cite

BackgroundOnly few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood.ObjectivesTo study the potential of flecainide to terminate acutely induced AF of short duration (≥15 minutes), to examine flecainide‐induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length, and ventricular depolarization and repolarization.AnimalsNine Standardbred horses. Eight received flecainide, 3 were used as time‐matched controls, 2 of which also received flecainide.MethodsProspective study. The antiarrhythmic and electrophysiologic effects of flecainide were based on 5 parameters: ability to terminate acute pacing‐induced AF (≥15 minutes), and drug‐induced changes in atrial effective refractory period, AF duration, AF vulnerability, and ventricular depolarization and repolarization times. Parameters were assessed at baseline and after flecainide by programmed electrical stimulation methods.ResultsFlecainide terminated all acutely induced AF episodes (n = 7); (AF duration, 21 ± 5 minutes) and significantly decreased the AF duration, but neither altered atrial effective refractory period nor AF vulnerability significantly. Ventricular repolarization time was prolonged between 8 and 20 minutes after initiation of flecainide infusion, but no ventricular arrhythmias were detected.Conclusions and Clinical ImportanceFlecainide had clear antiarrhythmic properties in terminating acute pacing‐induced AF, but showed no protective properties against immediate reinduction of AF. Flecainide caused temporary prolongation in the ventricular repolarization, which may be a proarrhythmic effect.

show abstract

“…[1][2][3][4] The treatment is effective in approximately 80% of horses but involves a range of dose-related and idiosyncratic toxic responses varying from mild and benign to fatal. [1][2][3][4] Additional therapeutic modalities are required to avoid these adverse effects and to provide options for those horses that fail to respond to, or are intolerant of, quinidine salts.…”

Section: Anagement Of Atrial Fibrillation (Af) In Horses Hasmentioning

confidence: 99%

Transvenous Electrical Cardioversion of Equine Atrial Fibrillation Technical Considerations

Kimberly

McGurrin

Physick‐Sheard

et al. 2005

Journal of Veterinary Internal Medicine

View full text Add to dashboard Cite

Conventional treatment of equine atrial fibrillation (AF) involves administration of quinidine salts. Most uncomplicated cases respond to treatment, but pharmacologic cardioversion involves a range of adverse effects, and some horses are unable to tolerate medication. A study was undertaken to develop transvenous electrical cardioversion (TVEC) as an alternative treatment. Safety issues and catheter placement techniques with catheter-integrated cardioversion electrodes were investigated, and responses to shock application were evaluated. After the premortem catheterization of elective-euthanasia horses, no tissue abnormalities were detected at postmortem examination. To evaluate the response to the application of shocks and appropriate electrode positions, an electrical cardioversion of research horses in chronic AF was then attempted. After catheterization of the right atrium (RA) and pulmonary artery through the right jugular vein, horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energies until cardioversion was achieved or until a maximum energy of 300 J was reached. Five treatment events were applied to 3 horses, with cardioversion achieved in one of the treatment events. No adverse effects of cardioversion attempts or general anesthesia were observed. The procedure was then applied to 8 client-owned horses, with cardioversion achieved in 7. No adverse responses to appropriately delivered shocks were observed. No antiarrhythmic medications were administered to any horse at any stage. Catheter design and placement technique evolved throughout the study, with combined ultrasonography and pressure guidance proving most effective in achieving appropriate electrode placement. Results suggest TVEC, as applied in the present study, is a safe, effective, and realistic therapeutic option for equine AF.Key words: Cardiac disease; Electrophysiology; Heart; Horse. Management of atrial fibrillation (AF) in horses has traditionally involved the administration, PO and, more recently, IV, of a quinidine salt.1-4 The treatment is effective in approximately 80% of horses but involves a range of dose-related and idiosyncratic toxic responses varying from mild and benign to fatal.1-4 Additional therapeutic modalities are required to avoid these adverse effects and to provide options for those horses that fail to respond to, or are intolerant of, quinidine salts.Electrical cardioversion involves the application of electrical shock (with a defibrillator) with the goal of depolarizing all or part of the atrial myocardium. Electrical cardioversion of AF is becoming routine in human medicine, because the efficacy of this modality is often higher than that of pharmacologic methods for the restoration of sinus rhythm.5 In humans, lower energy requirements and higher efficacy have been reported with internal electrical cardioversion with catheter-mounted electrodes (transvenous electrical cardioversion [TVEC]) than with external techniques with thoracic paddles, 5-7 ...

show abstract

Treatment of Atrial Fibrillation in Horses: New Perspectives

Cited by 94 publications

References 30 publications

Safe and Efficacious Dosage of Flecainide Acetate for Treating Equine Atrial Fibrillation.

Safe and Efficacious Dosage of Flecainide Acetate for Treating Equine Atrial Fibrillation.

Antiarrhythmic and Electrophysiologic Effects of Flecainide on Acutely Induced Atrial Fibrillation in Healthy Horses

Transvenous Electrical Cardioversion of Equine Atrial Fibrillation Technical Considerations

Contact Info

Product

Resources

About