Page 103 - Rapid Review of ECG Interpretation in Small Animal Practice, 2nd Edition

Answers 35, 36 ECG Cases

Answer 35
VetBooks.ir 1 ECG 35 shows AF and a LBBB morphology.

2 • The heart rate is ~185 bpm. The rhythm is irregularly irregular. The QRS duration is prolonged
(>80 ms) due to a wide Q and R wave.
• The diagnosis of an LBBB is made based on a normal MEA of the QRS complex with increased
duration of the QRS.
• AF is a common sequela to atrial dilation associated with advanced dilated cardiomyopathy. Due to
the absence of P waves and the LBBB morphology, one may be inclined to make a diagnosis of VT
in this ECG. The key feature to recognize AF with a LBBB is the irregularity of the rhythm; VT is
usually more regular.
• AF in the setting of advanced myocardial failure is typically associated with tachycardia and can lead
to exacerbation of heart failure signs, such as ascites or pulmonary edema.

Answer 36

1 ECG 36 shows polymorphic VT.
2 • Five sinus beats (black arrows) are seen. The other complexes are wide and bizarre compared to the
normal sinus beats, indicating a ventricular origin. A short period of VT consisting of five ventricular
premature beats (blue arrows) is detected in the middle of the recording, with a heart rate of
200 bpm. The VPCs have two different and distinct morphologies (i.e., polymorphic), suggesting that
they arise from two different areas within the ventricles.
• There is one potential fusion beat (green arrow), indicating simultaneous ventricular depolarization
from a sinus impulse and a ventricular ectopic impulse. The resultant QRS complex morphology is a
combination of a normal sinus QRS and abnormal VPC QRS.
• In this case, dilated cardiomyopathy was diagnosed via echocardiography and the antiarrhythmic
agent sotalol was prescribed, based on the presumption that syncope was being caused by longer runs
of polymorphic VT.

36
I

II

III

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