![]() ![]() Coarse oscillation of the baseline (F-waves)Įchocardiography is recommended to determine the type and severity of any underlying structural heart disease.Regular saw-tooth deflections of baseline.There may also be a variable pulse quality and a variable intensity of heart sounds. Findings on clinical examination will include an irregularly irregular heart rhythm on auscultation with no fourth heart sound. History and physical examination may provide a presumptive diagnosis for this condition. There may be a history of coughing, dyspnoea, tachypnoea, exercise intolerance, episodes of syncope. ![]() Other signs are generally related to the underlying disease process or congestive heart failure. This most commonly manifests as exercise intolerance. However, there may be signs of haemodynamic compromise due to the rapid heart rate and a loss of atrial contribution to ventricular filling which would usually account for up to 20% of cardiac output. Patients with primary atrial fibrillation are usually asymptomatic. Signs generally relate to the underlying disease process, which in cows can range from gastrointestinal diseases such as a left-displaced abomasum, to uterine torsion. It can be associated with exercise induced pulmonary haemorrhage, so this can be a clinical sign of the condition. If the horse is raced, hunted or an eventer, then signs may occur during exercise and include exercise intolerance, reluctance to exercise or a poor performance during exercise. The atrial contraction only contributes to around 15% of the ventricular filling, so signs of atrial fibrillation are only seen during vigorous exercise. This may be an incidental finding on clinical examination, especially if the horse is not used for highly athletic activities. Ventricular response rate is variable, depending on the degree of physiological AV block.Ītrial fibrillation can occur in all species when there is atrial dilation secondary to other cardiac lesions. It may be seen as a precursor to atrial fibrillation. In animals with primary 'lone' AF, ventricular response rate may be normal or only mildly elevated due to parasympathetic influence on the AV node.Ītrial Flutter: is similar to atrial fibrillation, but has sudden onset and termination and is therefore a transient arrhythmia. In animals with underlying heart disease, the ventricular response rate is usually elevated due to sympathetic predominance. It can occur in absence of structural heart disease (primary/lone AF), or secondary to underlying cardiac disease. As a result there is an irregular ventricular response. While the atria fail to contract some of the disorganised depolarisation waves are conducted through the AV node, reaching the ventricles. Atrial fibrillation is the commonest pathological dysrhythmia.Ītrial Fibrillation (AF): Occurs when many ectopic waves of depolarisation spread throughout the atria. ![]()
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