Re: Syncope in a young woman
There are two aspects of my response to this article:-
A. The explaination by authors in defence of diagnosis of WCT as “preexcitation tachycardia” is not complete.
1. Absence of P waves, the wide QRS tachycardia, and the irregular ventricular rate; none of these criteria are 100% specific for AF. Polymorphic VT can also have all these findings on ECG including irregular ventricular rhythm.
2. Authors of the article claim (in defence of their diagnosis) that “Polymorphic ventricular tachycardia is associated with QRS axis twisting and therefore unlikely.” Basically presence of QRS twisting has never been included as a criterion of VT. Twisting suggests a specific form of polymorphic VT, called Torsade de Pointes. All TdPs are Polymorphic VT, but all polymorphic VTs are not TdP.
So, in summary there is not a single argument in favour of preexcitation tachycardia that can be considered against a diagnosis of VT for the published rhythm strip.
B. The diagnosis for published rhythm strip should be VT. Following findings supports the diagnosis:-
1. Extreme QRS axis in frontal plane.
2. Presence of initial R wave in lead aVR:- it is 100% specific for VT. Any form of bundle branch block cannot produce this finding, so SVT with aberrancy is ruled out as diagnosis. In case of preexcitation tachycardia the direction of ventricular depolarisation is from base towards apex, so this also can never produce an R wave in aVR.
The above two points are enough for making a diagnosis of VT for this patient. But we should also explain one more finding.
3. That finding is an odd thing for VT in the published rhythm strip--the “irregularity of ventricular response”. This is also described for VT. In current ECG this seems like “cooling down and warming up phenomenon of VT”, as the available long lead II can be divided in repeats of some 10-11 beats. Every repeat sequence shows acceleration of heart rate in first 5-6 beats and deceleration in next 4-5 beats. So, basically the irregularity of the tachycardia also have “certain” regularity. And any kind of regularity should be taken against the diagnosis of AF. Availability of a longer strip would have been better to appreciate the regularly irregular tachycardia.
At last, it will be interesting to know the findings of any EP study (if available) for the index patient. And even if the findings of EP study suggest preexcitation tachycardia, then also this published ECG strip remains a VT and should be managed accordingly.
Competing interests: No competing interests