Ventricular Tachycardia in a Patient with Permanent Pacemaker

Report:

Ventricular tachycardia 154/min

?Retrograde VA conduction

Comment:

The QRS is a monophasic R wave in V1, just over 0.16” long: both the morphology and the QRS duration support the diagnosis of VT. The duration criterion is > 0.14” for V1 positive (RBBB-like) and > 0.16” for V1 negative (LBBB-like) patterns.

The axis is indeterminate, ‘northwest’ or ‘nonsense’ axis, supporting, albeit not very strongly, the diagnosis of VT.

The patient was normally in sinus rhythm with complete AV block, requiring a permanent pacemaker (Fig 104a). This makes one wonder about the likelihood of retrograde 1:1 conduction suggested by the Lead 2 rhythm strip. Sometimes the retrograde conduction is preserved despite permanent antegrade 3o block. In this instance, one cannot tell for sure where the QRS ends in the standard leads. The terminal negative blip could be a retrograde P wave or a secondary S wave. I prefer the latter: the paced beats have the same terminal negative deflection despite the proximity of blocked P waves in the tracing below (Fig 104a).