Tuesday, November 16, 2010

Wide Complex Tachycardia; It's really sinus, RBBB + LAFB, and massive ST elevation

Here are more examples of wide complex tachycardia: 
these are all a mix of ventricular tachycardia and SVT with aberrancy.

This 51 yo male complained of chest pain, then had a v fib arrest. He was resuscitated and brought to the ED where this ECG was recorded. He was in cardiogenic shock.



There is tachycardia, and there is a wide complex. This wide complex tachycardia could easily be misdiagnosed as V tach. However, there are p-waves, and this is a classic RBBB + LAFB (left anterior fascicular block) morphology. When V tach originates in the left ventricle, there may be an RBBB-like complex, but because VT originates in the myocardium, not in the left bundle (as does RBBB), it does not look exactly like RBBB, as this one does. The left anterior fascicular block can be diagnosed by the left axis deviation. RBBB alone would have S-waves in I and aVL; since there are late large R-waves, there is LAFB.

So now we can say it is sinus tach with RBBB + LAFB.
Is there ST elevation? One must find the end of the QRS in order to determine this. I have done this and marked it up in the image below. The end of the QRS is easy to find in V1. One can then draw a line down to the rhythm strip at the bottom, which is lead II. Thus, you can find where in lead II is the end of the QRS. Then you can go to all parts of the ECG to find the end of the QRS.

As you will see, this results in the discovery of ST elevevation in V2-V4 and I and aVL, diagnostic of anterolateral STEMI.





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