November 3, 2016

Wide QRST: VT or not?

Vignette: A 60 yo patient with history of HTN and DM admitted due to sepsis. Monitoring captured this. What is the ECG interpretation?

Image 1 - Image  case in full disclosure

Review of telemetry data revealed  sudden onset of tachycardia with distinct P waves noted in lead I (Image 2). Also noted are wide (aberrant) beats. In lead I, the P waves were noted to disappear but later complexes showed marked prominence of the T waves. This would mean that the P wave were "buried" in the T waves. 

Image 2 - Initiation of the arrhythmia
The arrhythmia continued as narrow complex tachycardia (image 3). P waves can be seen distorting the descent of the T waves in lead II. 

Image 3
Later, alternating bundle branch block (left bundle branch block) morphology was noted (Image 4). Still with P waves noted.

Image 4
After a few seconds, all the complexes were of LBBB morphology. P waves are difficult to appreciate (Image 5).

Image 5 - Image case
Later, there was spontaneous termination of the tachycardia (Image 6) and gradual normalization of the QRS duration.

Image 6
In the case presented, the morphology of V1 do not look like ventricular tachycardia (VT). For VT, a LBBB morphology will be as shown in Image 7. So, we are confident that this could either be tachycardia in the setting of a fixed bundle branch block or aberrancy.

Image 7 - VT morphology in V1

The issue of aberrancy can be observed only by continuous observation. It is difficult for a 10 seconds strip to capture all the changes. You are so lucky to capture the changes on a 12 lead. 

What about the rhythm? It can be clear at the beginning of the arrhythmia that this is atrial tachycardia and later the QRS had an aberrant morphology. There was spontaneous termination and later normalization of the QRS duration as the rate slowed down. Thus, this was a case of paroxysmal atrial tachycardia with episodes of aberrancy (rate-dependent).


Garner JB and Miller JM. 2013. Wide Complex Tachycardia – Ventricular Tachycardia or Not Ventricular Tachycardia, That Remains the Question. Arrhythmia & Electrophysiology Review 2(1):23–29

Wellens HJ. 2001. Ventricular tachycardia: diagnosis of broad QRS complex tachycardia. Heart 86:579–585

Sousa et al. 2012. The Value of Electrocardiography in the Differential Diagnosis of Wide QRS Complex Tachycardia. Rev Port Cardiol 33:165---173

Fisch C. 1983. Aberration: seventy five years after Sir Thomas Lewis. Br Heart J; 50: 297 -302

Fisch C., Zipes DP and McHenry PL. 1973. Rate Deependent Aberancy. Circ 48:714-724 


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