Atrial fibrillation is a disturbance of the cardiac rhythm associated with poor perfor- mance in athletic horses. Quinidine is the drug of choice for restoring sinus rhythm in horses because of its high success rate (85%) in cases with no anatomical lesions of the atrial myocardium. However, side effects and adverse effects are commonly reported with quinidine cardioversion. Nose-gastric administration is frequently associated with nasal mucosal edema, urticaria, paraphymosis, hypotension, colic and diarrhea. Further- more, proarrhythmic effects of quinidine can induce rapid ventricular tachycardia (Btorsade des pointes^) and sudden death. Therefore, pharmaceutical alternatives to quinidine, with less side effects and similar efficacy, would be desirable. Flecainide has been found to be well tolerated and easy to administer and preliminary studies in horses with induced AF and acute AF suggested that it is effective in restoring sinus rhythm (Ohmura et al., 2000, 2001). Flecainide is an antyarrhythmic agent of Vaughan- Williams class IC which strictly binds to and blocks the fast Na-channel, decreasing maximum velocity of depolarization during phase 0 and prolonging the action potentials in the atrial and ventricular myocardium and in the Purkinje fibers. This results in slow- ing of the conduction through these structures, particularly within the His-Purkinje sys- tem. Electrocardiographically the P-R interval and the QRS duration prolong, as does the Q-T interval, even though shortening of the J-T interval (from the end of the QRS to the end of the T wave) is commonly seen. A recent clinical study of 10 horses with natural occurring AF treated with flecainide found that just one horse converted to sinus rhythm, while the remainder were cardioverted using the Bclassical^ quinidine protocol 273 274 (Van Loon et al., 2004). The aim of the present study was to focus on the effectiveness and safety of flecainide in horses with chronic atrial fibrillation that were not amenable to quinidine cardioversion.
Treatment of chronic atril fibrillation in the horse with flecainide: personal observation.
SGORBINI, MICAELA
2007-01-01
Abstract
Atrial fibrillation is a disturbance of the cardiac rhythm associated with poor perfor- mance in athletic horses. Quinidine is the drug of choice for restoring sinus rhythm in horses because of its high success rate (85%) in cases with no anatomical lesions of the atrial myocardium. However, side effects and adverse effects are commonly reported with quinidine cardioversion. Nose-gastric administration is frequently associated with nasal mucosal edema, urticaria, paraphymosis, hypotension, colic and diarrhea. Further- more, proarrhythmic effects of quinidine can induce rapid ventricular tachycardia (Btorsade des pointes^) and sudden death. Therefore, pharmaceutical alternatives to quinidine, with less side effects and similar efficacy, would be desirable. Flecainide has been found to be well tolerated and easy to administer and preliminary studies in horses with induced AF and acute AF suggested that it is effective in restoring sinus rhythm (Ohmura et al., 2000, 2001). Flecainide is an antyarrhythmic agent of Vaughan- Williams class IC which strictly binds to and blocks the fast Na-channel, decreasing maximum velocity of depolarization during phase 0 and prolonging the action potentials in the atrial and ventricular myocardium and in the Purkinje fibers. This results in slow- ing of the conduction through these structures, particularly within the His-Purkinje sys- tem. Electrocardiographically the P-R interval and the QRS duration prolong, as does the Q-T interval, even though shortening of the J-T interval (from the end of the QRS to the end of the T wave) is commonly seen. A recent clinical study of 10 horses with natural occurring AF treated with flecainide found that just one horse converted to sinus rhythm, while the remainder were cardioverted using the Bclassical^ quinidine protocol 273 274 (Van Loon et al., 2004). The aim of the present study was to focus on the effectiveness and safety of flecainide in horses with chronic atrial fibrillation that were not amenable to quinidine cardioversion.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
