The Patient:   This ECG was obtained from a 29-year-old man who was found by his wife, prone on the floor. He was unresponsive. When paramedics arrived, they found him to be in V fib.  He was shocked at 360 J twice, with no conversion.  The third shock was delivered using the dual sequential method, delivering 720 J.  That shock resulted in conversion to the rhythm you see here.  We don’t have information on any previous medical history, or on the outcome of the patient after he was transported to the hospital.  During transport, he received Esmolol 40 mg IVP and Amiodarone 150 mg in 50 ml, administered over ten minutes.

 The ECG:   The rhythm is regular, except for one slightly-early beat, third beat in. The only P wave seen is in the first beat, and the axis of that P wave is very rightward (negative in Lead I). This could be an artifact, or represent an atrial ectopic beat. There are no obvious signs of lead misplacement.  Without P waves, this regular rhythm would have to be called accelerated junctional rhythm. Since this man was just shocked three times, at high doses, I would want to let the rhythm “settle” a bit before deciding what to name it.  For now, it is fast enough to produce pulses, and a workable BP, and not so fast as to stress the heart.  I would be satisfied with that for the time being. 

The ECG machine measures the QRS duration at .183 seconds.  This is the width of that one stray ventricular beat – technically a PVC, but late enough to have some escape characteristics. The rest of the QRS complexes on the page are quite narrow: about .07 seconds, or 70 ms. See Leads III, V1 and V2.  Remember, the channels on this ECG are run simultaneously. The beats shown in a vertical stack are the same beat, and will have the same intervals as the other beats in that vertical line. 

So, what made the QRS complexes look wide and fool the machine?

There is significant ST elevation in the following leads:  I, II, aVL, aVF, V3, V4, V5, and V6. The ECG machine agrees.  There is also reciprocal ST depression in aVR, V1, and V2.  And possibly a little in Lead III, though it is more of a sagging shape than J point depression. This is the pattern of a large posterior-lateral occlusive myocardial infarction (OMI).  We know that this patient had a period of pulselessness due to V fib.  Signs of ischemia, even Type II OMI (not due to a blood clot), are definitely a possibility after such trauma to the heart. There is also the possibility that the patient had a massive OMI, probably due to occlusion of the circumflex artery or it’s branches, and that OMI caused the V fib.  The machine has mistaken the dramatic ST elevation for wide QRS complexes.  This OMI pattern should be considered to be an acute OMI until proven otherwise.  Since we have no follow up on this patient, we do not know for sure.  I will update this comment if I receive more information.