Ventricular Tachycardia Rightly (Mis)diagnosed

Report:

Ventricular tachycardia 170/min

Comment:

There is nothing against the diagnosis of VT in this trace, and a lot in its favour: monophasic R waves in V1 with left rabbit ear taller than the right and QRS duration over 0.14” (in basic RBBB morphology); further, the precordial pattern shows positive concordance.

The patient failed to respond to two boluses of sotalol 40mg IV and was cardioverted by 18 mg adenosine IV. This be itself is not necessarily against the diagnosis of VT – some are adenosine-sensitive. But what followed overturned the diagnosis decisively: the sinus rhythm trace (Fig 54a) contained broad premature beats of the same morphology as the tachycardia – but preceded by premature atrial (P’) waves! This alone supersedes all the other criteria for or against VT and obviates the need for them. The correct diagnosis is now atrial tachycardia with (atypical) RBBB/LAHB aberrancy53.

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