engleski

Skipped beat - Arrhythmias in the ER patients

Cardiac arrhythmia or dysrhythmia can be defined as any disorder of cardiac rhythm that is not considered normal for a healthy dog or cat. All normal cardiac rhythms originate from the sinus node. In dogs normal rhythms include: sinus rhythm, respiratory sinus arrhythmia and second degree atrioventricular block ; sinus bradycardia can be observed in healthy large-breed dogs at rest, and sinus tachycardia is seen with excitement/stress. With cats the situation is different – sinus rhythm and sinus tachycardia are considered as normal, and in cats at rest sinus arrhythmia and sinus bradycardia can be seen, rhythms that are rarely seen in veterinary practice environment. There are two main groups of causes of cardiac arrhythmias: first group comprises primary cardiac diseases and the second group extracardiac diseases. The most common causes of cardiac arrhythmias are: trauma, splenic tumors, gastric dilatation volvulus, canine dilated cardiomyopathy, urethral obstruction in cats, heat stroke and feline cardiomyopathies. In regard to ventricular arrhythmias, in dogs severe systemic diseases often results in their development, whilst in cats with ventricular arrhythmias the commonest cause is an underlying myocardial disease. Cardiac arrhythmias should be considered whenever an animal experiences syncope, weakness, or collapse, and sometimes the owners detect very fast/very slow heart rates, or an irregular heart rhythm. The history mainly reflects the signs of the disease that has led to the development of arrhythmia: in cases of systemic disease vomiting, hemoabdomen etc., or primary cardiac disease collapse, respiratory distress, weakness or exercise intolerance. Identification of a tachycardia, bradycardia or irregular rhythm is essential to raise suspicion of arrhythmia and decision to obtain an ECG. Clinically, tachycardic animals often have pulse deficits and variable arterial pulses. In animals with an underlying cardiac disease a heart murmur or gallop can be heard. Furthermore, signs of congestive heart failure (respiratory distress, ascites, jugular distension and so on) may be present, and in animals in which a systemic disease has led to the development of arrhythmia clinical signs often reflect the disease. The key diagnostic tool or, better put, diagnostic “gold standard” for identification and differentiation of cardiac arrhythmias is the ECG. In those animals with suspected underlying cardiac disease, in addition to the ECF, routine diagnostic work-up includes also echocardiography, and thoracic radiography. As in any other emergency patient baseline laboratory testing should be performed. In older cats thyroid testing is recommended and should also be done in dogs under thyroid supplementation therapy. Additional (specialized) testing is appropriate based on suspected underlying diseases. Treatment of cardiac arrhythmias includes medical management, radioablation and pacemaker therapy. Generally speaking, in majority of tachyarrhythmias medical management with the use of antiarrhythmic drugs is indicated ; bradyarrhythmias are rarely managed medically – therapy of choice is permanent pacemaker implantation.

emergency, arrhythmias, dog, cats, diagnosis, treatment

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