Atrial fibrillation vs Atrial Flutter
Atrial fibrillation is the commonest pathological dysrhythmia.
Atrial Fibrillation (AF): Occurs when many ectopic waves of depolarisation spread throughout the atria. While the atria fail to contract some of the disorganised depolarisation waves are conducted through the AV node, reaching the ventricles. As a result there is an irregular ventricular response. It can occur in absence of structural heart disease (primary/lone AF), or secondary to underlying cardiac disease. In animals with underlying heart disease, the ventricular response rate is usually elevated due to sympathetic predominance. In animals with primary ‘lone’ AF, ventricular response rate may be normal or only mildly elevated due to parasympathetic influence on the AV node.
Atrial Flutter: is similar to atrial fibrillation, but has sudden onset and termination and is therefore a transient arrhythmia. It may be seen as a precursor to atrial fibrillation. Ventricular response rate is variable, depending on the degree of physiological AV block.
Atrial fibrillation can occur in all species when there is atrial dilation secondary to other cardiac lesions.