A 24 years old male patients was refferent for electrophysiological study and ablation of a wide complex QRS tachycardia. We start with programmed ventricular stimulation (for evaluating the VA conduction) and wide QRS complex tachycardia was induced. Subsequently it was induced also by atrial stimulation.
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| wide QRS tachycardia |
During tachycardia we noted in some instances atrio-ventricular dissociation and a constant retrograde His capture (marked by arows in the picture). Important to mention that all the time was a His-ventricular association. Regarding these aspects (atrio-ventricular dissociation, retrograde His capture, morphology of the tachycardia) the diagnostic was Idiopathic Left Ventricular Tachycardia (ILVT) .
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| Tachycardia and His potentials |
But... sometimes, and quite often, it was observed a 2/1 ventriculo-atrial block. In the first subsequent picture you can note a retrograde P wave with a constant 2/1 VA block. The next picture shows very interesting that, after a retrograde atrial capture, there is also an antegrade capture of the His (with an infrahisian colision with the impulse conducted retrogradly from the ventricle, in other words the negative HV interval is still present but shorter), this antegrade capture and infrahisian colision perpetuating the 2/1 block.
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2/1 VA block |
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| 2/1 VA Block with antegrade His capture |
AVRT was ruled out by thr AV dissociation and 2/1 VA block and AVNRT by the negative HV interval. Interfascicular reentry is still theoretical possible, but regarding the age... and the mechanical abolition of arrhythmia (during left ventricular mapping) without a fascicular block I think is improbable.
Some nice manifestations of the 2/1 retrograde block:
-constant ventricular capture of the atrial-His depolarisation creating the aspect of the pseudo-ventricular bigeminism
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| pseudo-ventricular bigeminism |
- sometimes, the same phenomen but with ventricular fusion beat; in this picture His depolarisation and positive HV interval can be noted, as well as the retrograde His depolarisation
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| ventricular fusion beats alternating with tachy beats in a 2:1 |
-in the subsequent picture all these aspects can be observed: retrograd His capture, ventricular fusion beat (with a positive HV interval, but shorter than in sinus rhythm), ventricular capture beat (QRS morphology , same HV interval as in sinus rhythm)
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retrograde His capture, ventricular capture and fusion beats |
During mapping in the left ventricle the tachycardia became no more inductible (mechanical supression, not rare in the ILVT) and it was succesfuly ablated in another session few weeks later.
I wait your comments about the tracings...
I do not understand why do you see fascicular VT only theoretically possible (the age is concordant and mechanical abolition is also possible even if you don't produce a persistent fascicular block).
ReplyDeleteBy idiopathic left ventricular tachycardia I ment fascicular tachycardia (reentry). So maybe we speak about the same thing. If you mean fascicular automatic tachycardia... it is usualy no induced by programmed stimulation and the HV association is not so clear (of course is not obligatory in ILVT too, but usualy is present). Regarding the interfascicular reeantry is improbable because usualy is present in patient with heart disease (prior MI, preexisting bifascicular block ...), and I think you should produce a fascicular block (even transient by mechanical abolition) to render the tachycardia noninducible.
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