Fascicular VT With Retrograde 2:1 Block

Report:

Ventricular tachycardia 122/min

Retrograde 2:1 V-A block

Retrograde 1o VA block (RP 0.24”)

Comment:

The tachycardia originates in the posterior-inferior fascicle of the left bundle branch - it looks like atypical RBBB + LAHB. Despite the relatively slow rate, the patient was distressed by palpitations and required cardioversion. The sinus rhythm trace (Fig 158a) shows widespread T wave inversion, presumably due to the preceding abnormal conduction in VT. Conduction, rather than rapid rate, appears responsible for this “post-tachycardia syndrome”.

The presence of retrograde 2:1 block is in itself evidence of ventricular ectopic origin of the broad-complex tachycardia5. It is rarely mentioned because it is rarely seen. The retrograde P waves in alternate cycles are readily seen in many leads. In V4 they mimic repolarisation alternans.

Fascicular VT has been frequently reviewed122.

If you have any suggestions for or feedback on this report, please let us know.