How is ventricular tachycardia (VT) differentiated from sinus tachycardia?

Updated: Dec 05, 2017
  • Author: Steven J Compton, MD, FACC, FACP, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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The image below demonstrates a tachycardia with a 1:1 atrial-to-ventricular ratio. It is not immediately clear whether the atria are driving the ventricles (sinus tachycardia) or the ventricles are driving the atria (VT).

This electrocardiogram is from a 32-year-old woman This electrocardiogram is from a 32-year-old woman with recent-onset heart failure and syncope.

In this case, a diagnosis of sinus tachycardia would require the presence of severe conduction disease manifesting as marked first-degree AV block with left bundle-branch block. However, close inspection shows that the actual diagnosis is VT, as indicated by absence of RS complexes in the precordial leads, a QS pattern in lead V6, and an R wave in lead aVR. The patient proved to have an incessant VT associated with dilated cardiomyopathy.

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