Anaesthetic management of a horse with atrial fibrillation undergoing transvenous electrical cardioversion in combination with amiodarone

Abstract

A 664 kg, 19‐year‐old, Irish sport horse gelding with chronic atrial fibrillation presented for transvenous electrical cardioversion under general anaesthesia. Five incremental electrical shocks were delivered in combination with intraoperative pharmacological cardioversion using amiodarone, which caused significant arterial hypotension treated with dobutamine infusion. Final successful cardioversion to sinus rhythm was achieved, and the horse recovered smoothly from general anaesthesia. Unfortunately, atrial fibrillation reoccurred early in the postoperative period.

Early recognition with capnography, and successful resuscitation, of severe cardiac dysfunction in a horse receiving amiodarone during transvenous electric cardioversion (TVEC)

“…The intended amiodarone dose in our case was 1490 mg given over 15 min, translating to a rate of 99 mg/min. The actual dose administered in our case (total 300 mg; 0.5 mg/kg) was smaller than intended, and smaller than the dose used by Asorey and Corletto (2022), due to complications arising and drug cessation. However, despite the small total dose in our case, we cannot rule out the delivery of a rapid amiodarone bolus (suspected to be ~300 mg/min) after re‐establishing the patency of the IV cannula.…”

“…However, the nature of TVEC in horses makes general anaesthesia a prerequisite, which increases the perioperative risks (Gozalo‐Marcilla et al, 2021; Johnston et al, 2002). The ASA grade assigned to our case (II) is the same as that assigned to a similar case (Asorey & Corletto, 2022). However, in the paper by Hubbell et al (2022) AF was proposed to be equivalent to an ASA III (patient with severe systemic disease).…”

“…Side effects after IV amiodarone have previously been reported in humans, horses, dogs and rabbits, including hypotension and negative inotropy progressing to cardiovascular collapse (Asorey & Corletto, 2022; Cushing et al, 2010; Lessa & Tibiriçá, 2005; Somberg et al, 2005). It has been suggested that the cosolvents polysorbate 80 and benzyl alcohol in the standard IV formulation (Cordarone® Intravenous amiodarone hydrochloride) could drive these cardiovascular effects (Cushing et al, 2010).…”

“…It has been suggested that the cosolvents polysorbate 80 and benzyl alcohol in the standard IV formulation (Cordarone® Intravenous amiodarone hydrochloride) could drive these cardiovascular effects (Cushing et al, 2010). A recent case report of a horse undergoing TVEC and receiving amiodarone (two infusions of 2.5 mg/kg IV each given over 15 min) described arterial hypotension (MAP 47 mmHg), that responded to treatment with dobutamine (Asorey & Corletto, 2022). In our case, the first indicator of cardiac dysfunction was a decreasing E T CO 2 detected using capnography, rather than an acute drop in MAP.…”

Anti‐arrhythmic drugs before, during and after transvenous electrical cardioversion of atrial fibrillation in horses: Weighing the benefits and risks

“…While amiodarone seems to be a suitable option for difficult TVEC cases, caution is needed. A case report of Asorey and Corletto (2023) described the development of significant arterial hypotension with mean arterial pressure decreasing to 47 mmHg following amiodarone infusion in an anaesthetised horse with AF. Similarly, the case of Pye et al.…”