Case Studies

These case studies contain detailed information on the diagnostic and treatment process for each individual animal.

Lucky ECG case study

Lucky

Case Background

Name: Lucky
Age: 10 year old
Sex: Female, spayed
Breed: Standard Poodle

Clinical History

Please review Lucky’s clinical history.

Patient presented with a complaint of sudden lethargy. Lucky has had a known heart murmur for 3 years, but no echocardiogram had been performed and she had been asymptomatic. Patient now has weak and rapid femoral pulses, a soft systolic heart murmur at the left apex. An irregular tachycardia is auscultated as well .    

ECG

View Lucky’s electrocardiogram (the black bar represents one second)
What abnormalities are present on this ECG?
Relevant Findings: Average heart rate=200bpm, Atrial fibrillation with a right bundle branch blockAtrial fibrillation is recognized by the absence of P waves and irregularly irregular R-R intervals. There is a wide complex QRS with a negative polarity in Leads I, II, and III, with a positive T wave. This is suggestive of a right axis shift. The QRS is wide (0.08 sec) consistent with a right bundle branch block rather than right ventricular enlargement. Atrial fibrillation patients are usually tachycardic and typically have QRS complexes with a supraventricular (narrow) appearance. In this case, even though the complexes are supraventricular in origin, they are wide due to the conduction delay caused by the right bundle branch block. View an annotated image of Lucky’s ECG highlighting the relevant findings.  

 

Discussion & Treatment

 
Discussion:  The previous history of a heart murmur over several years duration suggests degenerative valve disease. The heart has likely been compensating for progressive valvular regurgitation with left-sided cardiac chamber dilation. Severe atrial enlargement can result in multiple wavelet reentry which is the underlying mechanism of atrial fibrillation. Right bundle branch block is a benign conduction disturbance that many times is not associated with gross structural or functional cardiac disease, but it can make rhythm diagnosis more challenging. Treatment/management: Treat with diltiazem 1.5mg/kg every 8 hours, consider adding digoxin 0.003mg/kg every 12 hours if the atrial fibrillation response rate does not decrease to < approximately 160 bpm with diltiazem alone.

    The CEG is funded through an educational grant from Boehringer Ingelheim Vetmedica, Inc., IDEXX Laboratories, Inc. and Nestle Purina PetCare.

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