Spontaneous resolution of hypothermia‐induced atrial fibrillation in a dog

Abstract

Objective: To report a case of spontaneous resolution of atrial fibrillation secondary to hypothermia in a dog without detectable heart disease. Case summary: An 8‐year‐old female spayed mixed breed dog presented with a history of prolonged exposure to below freezing environmental temperatures. The dog presented hypothermic (<32°C or <90°F) and minimally responsive to stimuli. The heart rate was 80 beats per minute (bpm) and irregular. Atrial fibrillation was diagnosed. The dog had pale mucous membranes, absent femoral pulses, and no obtainable blood pressure via indirect Doppler technique. Resuscitation fluids were administered and active external warming was instituted. Peripheral edema was observed during the rewarming phase and the irregular heart rate was noted to increase. The atrial fibrillation spontaneously resolved with no specific anti‐arrhythmic therapy. No underlying myocardial disease was found. The recovery of this dog was complete with a subsequent repeat of the echocardiogram and electrocardiogram (ECG) 8‐months later found to be within normal limits.

Rhythm disturbances associated with lidocaine administration in four dogs with supraventricular tachyarrhythmias

“…Paroxysmal supraventricular tachyarrhythmias can self-terminate without any intervention, especially when the substrate(s) and modulating factors that promoted the development and maintenance of supraventricular tachyarrhythmias can be removed. 5,6,9,10,28 However, in the authors' experience, this is not always possible. Without treatment, there is a possibility of persistent or permanent supraventricular tachyarrhythmias, even in dogs with normal cardiac morphology, and this prompted our therapeutic intervention.…”

“…1 In addition, hypothermia, hypothyroidism, and high vagal tone are also reported to be associated with AF. 1,[6][7][8][9] Resolution of these triggering factors can terminate AF, 6,9,10 ; however, this is often not possible or reliable in a clinical setting. Instead, treatment options for AF focus on either rhythm control (ie, cardioversion) or rate control.…”

ECG of the Month

“…The spontaneous resolution of hypothermia-induced AF is well documented in the human medical literature, 11,12 whereas only a few cases are documented in the veterinary medical literature. [13][14][15] Atrial fibrillation is characterized by an irregularly irregular rhythm. However, the initial ECG recording of the dog of the present report revealed a cyclic regularly irregular rhythm that was related to respiratory phases.…”