ECG of the month – February 2022

Davies Veterinary Specialists

Cardiology, Veterinary Professionals

18th February 2022

ECG of the month Feb

Six lead ECG. The top six leads (I, II, III, aVR, aVL, aVF) are all simultaneous recordings. The bottom, longer strip is a continuous recording of lead II. Paper speed: 50mm/sec, 0.5cm = 1mV.

A 7-year-old female Golden Retriever presents to your clinic for a dental cleaning and an arrhythmia is heard on physical examination. What is your rhythm diagnosis? What type of beat is denoted by the star? What are causes of this arrhythmia and what diagnostics would you recommend?

Rhythm diagnosis

Underlying sinus rhythm with two ventricular premature complexes (VPCs). VPCs have a wide and bizarre morphology and wide/bizzare T waves in the opposite direction of the QRS. Because these complexes arise from the ventricle, they are not associated with P waves. When a sinus beat and a ventricular beat occur at the same time, they can collide to create a beat with a morphology that is a mixture of both waveforms (deemed a fusion beat; denoted by the star). There is evidence of left ventricular enlargement as evidenced by increased QRS height of the sinus complexes.

Causes

Ventricular ectopy, regardless of underlying severity, can result from cardiac causes such as myocardial disease (hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy), infectious/inflammatory causes (myocarditis, endocarditis), cardiac neoplasia, or myocardial ischemia. However, non-cardiac disease can cause ectopy as well, including gastric dilatation volvulus, splenic/hepatic masses, seizures, increased circulating catecholamines (high sympathetic tone), or electrolyte disturbances.

Diagnostics

Electrolyte abnormalities should be ruled out initially. Then, work up for VPCs generally includes diagnostics to investigate cardiac disease (echocardiography, troponin, thoracic radiographs) and systemic disease (bloodwork, abdominal ultrasound). Holter monitor should be considered to further characterize frequency and severity of ventricular ectopy prior to and after initiation of therapy (if medications are warranted). However, if ventricular tachycardia is present, this is considered an emergency and treatment should not be delayed for the sake of Holter monitoring.

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