Page 126 - Small Animal Internal Medicine, 6th Edition

98 PART I Cardiovascular System Disorders

SYMPATHOMIMETIC DRUGS Coronel R, et al. Electrophysiological changes in heart failure and
Isoproterenol HCl is a β-receptor agonist that has been used their implications for arrhythmogenesis. Biochim Biophys Acta.
VetBooks.ir to treat symptomatic AV block or bradycardia refractory to Cote E, et al. Atrial fibrillation in cats: 50 cases (1979-2002). J Am
2013;1832:2432–2441.
atropine, although electrical pacing is safer and more effec-
Vet Med Assoc. 2004;225:256–260.
tive. It can also be effective for torsades de pointes, although
it could exacerbate this arrhythmia in some. Because of its Estrada AH, Pariaut R, Moise NS. Avoiding medical error during
electrical cardioversion of atrial fibrillation: prevention of unsyn-
affinity for β 2 -receptors, isoproterenol can cause hypoten- chronized shock delivery. J Vet Cardiol. 2009;11:137–139.
sion. It is not used for treating either heart failure or cardiac Finster ST, et al. Supraventricular tachycardia in dogs: 65 cases
arrest. Isoproterenol can be arrhythmogenic, as can other (1990-2007). J Vet Emerg Crit Care. 2008;18:503–510.
catecholamines. The lowest effective dose (see Table 4.2) is Gelzer AR, et al. Combination therapy with digoxin and diltiazem
used, and the animal is monitored closely for arrhythmias. controls ventricular rate in chronic atrial fibrillation in dogs
Oral administration is not effective because of marked first- better than digoxin or diltiazem monotherapy: a randomized
pass hepatic metabolism. crossover study in 18 dogs. J Vet Intern Med. 2009;23:499–508.
Terbutaline sulfate is a β 2 -receptor agonist that could have Gelzer AR, et al. Combination therapy with mexiletine and sotolol
a mild stimulatory effect on heart rate when given orally. suppresses inherited ventricular arrhythmias in German Shep-
Methylxanthine bronchodilators (such as aminophylline and herd dogs better than mexiletine or sotolol monotherapy: a ran-
domized cross-over study. J Vet Cardiol. 2010;12:93–106.
theophylline) increase heart rate in some dogs with sick Johnson MS, Martin M, Smith P. Cardioversion of supraventricular
sinus syndrome or AV block when used at higher doses. tachycardia using lidocaine in five dogs. J Vet Intern Med.
2006;20:272–276.
OTHER DRUGS Kellum HB, Stepien RL. Third degree atrioventricular block in 21
Edrophonium chloride is a short-acting anticholinesterase cats (1997-2004). J Vet Intern Med. 2006;20:97–103.
with nicotinic and muscarinic effects. Although mainly Kovach JA, Nearing BD, Verrier RL. Anger-like behavioral state
used for diagnosing myasthenia gravis, it slows AV con- potentiates myocardial ischemia-induced T-wave alternans in
duction, which can help in the diagnosis and resolution of canines. J Am Coll Cardiol. 2001;37:1719–1725.
some cases of acute SVT. The drug’s effect begins within Kraus MS, et al. Toxicity in Doberman Pinschers with ventricular
1 minute and lasts up to 10 minutes after IV injection. arrhythmias treated with amiodarone. J Vet Intern Med.
2009;23:1–6.
Adverse effects are primarily cholinergic and include GI Menaut P, et al. Atrial fibrillation in dogs with and without struc-
(vomiting, diarrhea, salivation), respiratory (bronchospasm, tural or functional cardiac disease: a retrospective study of 109
respiratory paralysis, edema), cardiovascular (bradycar- cases. J Vet Cardiol. 2005;7:75–83.
dia, hypotension, cardiac arrest), and muscular (twitching, Meurs KM, et al. Use of ambulatory electrocardiography for detec-
weakness) signs. Atropine and supportive care are used if tion of ventricular premature complexes in healthy dogs. J Am
necessary. Vet Med Assoc. 2001;218:1291–1292.
Phenylephrine HCl is an α-adrenergic agonist that Meurs KM, et al. Comparison of the effects of four antiarrhythmic
increases blood pressure by peripheral vasoconstriction. A treatments for familial ventricular arrhythmias in Boxers. J Am
baroreflex-mediated increase in vagal tone slows AV con- Vet Med Assoc. 2002;221:522–527.
duction and is thought to underlie its effects on SVT. Phen- Miyamoto M, et al. Acute cardiovascular effects of diltiazem in
ylephrine’s pressor effect begins rapidly after IV injection anesthetized dogs with induced atrial fibrillation. J Vet Intern
Med. 2001;15:559–563.
and persists for up to 20 minutes. The drug is contraindi- Moneva-Jordan A, et al. Sick sinus syndrome in nine West High-
cated in patients with hypertension or ventricular tachycar- land White Terriers. Vet Rec. 2001;148:142–147.
dia. Extravasation can cause ischemic necrosis of surrounding Oyama MA, Prosek R. Acute conversion of atrial fibrillation in two
tissue. dogs by intravenous amiodarone administration. J Vet Intern
Med. 2006;20:1224–1227.
Pariaut R, et al. Lidocaine converts acute vagally associated atrial
Suggested Readings fibrillation to sinus rhythm in German Shepherd dogs with
Arrhythmias and Antiarrhythmic Drugs inherited arrhythmias. J Vet Intern Med. 2008;22:1274–1282.
Bicer S, et al. Effects of chronic oral amiodarone on left ventricular Penning VA, et al. Seizure-like episodes in three cats with intermit-
function, ECGs, serum chemistries and exercise tolerance in tent high-grade atrioventricular dysfunction. J Vet Intern Med.
healthy dogs. J Vet Intern Med. 2002;16:247–254. 2009;23:200–205.
Bright JM, Martin JM, Mama K. A retrospective evaluation of Riesen SC, et al. Pharmacokinetics of oral ivabradine in healthy
transthoracic biphasic electrical cardioversion for atrial fibrilla- cats. J Vet Pharmacol Ther. 2011;34:469–475.
tion in dogs. J Vet Cardiol. 2005;7:85–96. Riesen SC, et al. Effects of ivabradine on heart rate and left ven-
Brundel BJJM, et al. The pathology of atrial fibrillation in dogs. J tricular function in healthy cats and cats with hypertrophic car-
Vet Cardiol. 2005;7:121. diomyopathy. Am J Vet Res. 2012;73:202–212.
Cober RE, et al. Pharmacodynamic effects of ivabradine, a negative Santilli RA, et al. Utility of 12-lead electrocardiogram for differen-
chronotropic agent, in healthy cats. J Vet Cardiol. 2011;13: tiating paroxysmal supraventricular tachycardias in dogs. J Vet
231–242. Intern Med. 2008;22:915–923.
Cober RE, et al. Adverse effects of intravenous amiodarone in 5 Saunders AB, et al. Oral amiodarone therapy in dogs with atrial
dogs. J Vet Intern Med. 2009;23:657–661. fibrillation. J Vet Intern Med. 2006;20:921–926.