7.1 Clinical examination of horses with arrhythmias
Clinical examination of horses with arrhythmias may reveal a number of different findings depending on the type of arrhythmia and its severity and the presence or absence of underlying heart disease. Arrhythmias may be continuous or intersome are present only at rest, or during or after exercise. Presenting signs vary from poor athletic performance to congestive heart failure, syncope, collapse and sudden death, or the arrhythmia may be an incidental finding. The arterial pulse may be normal, rapid or slow in rate; normal, weak or strong in quality; regular or irregular. A pulse deficit occurs when the stroke volume of a contraction is too small to produce a palpable change in arterial pressure and when ventricular contraction takes place, systolic sounds are heard, but a weak or absent pulse is palpated. The heart sounds may be abnormally loud, quiet or absent. Auscultation is particularly useful for rhythm analysis in the horse comwith small animals and humans because the sound associated with atrial contraction (54 or A sound) can be heard in most normal animals. It is therefore possible to identify whether atrial depolarisation has occurred. During ausculsome time should be spent specifically assessing cardiac rhythm before concentrating on murmurs. However, some arrhythmias can only be detected electrocardiographically.