ECG of the Week: ECG of the Week - 2nd June 2014

Friday 6 June 2014

ECG of the Week - 2nd June 2014 - Interpretation

This ECG is from a 65 yr old female who presented to the Emergency Department complaining of chest pain.
Check out the comments on our original post here.

Click to enlarge

Rate:

72 bpm

Rhythm:

Regular
A-V Sequential pacing

Nil p wave visible

Nil native atrial or ventricular activity noted

Axis:

Extreme / NW axis (-110 deg)

Intervals:

QRS - Prolonged (200ms)
QT - 560ms (QTc Bazette 380-400 ms)

Segments:

Discordant ST segment change

Some commenters were concerned about potential ST elevation in aVR. I think the J-point in this lead is subtly depressed
I think the significant QRS prolongation and fragmentation is causing some confusion as to the J-point location
The image below shows leads aVR and aVL with the green lines denoting the end of the QRS complex and the blue line the baseline to help show the relative positions of the QRS complex, J-point, and ST segment.

Click to enlarge

Additional:

Ventricular pacing consists of 2 spikes ~20-40 apart

Best seen in right precordial leads
Like LV pacing (small spike) followed by RV pacing (large spike)
Referred to as LV-RV Offset

Negative QRS vector leads I, II, III, aVF, V2-6

Due to infero-apical lead positioning

Wide tall R wave lead V1

Predominant LV capture

Notching within QRS complex

Likely reflects significant myocardial scarring and injury as does QRS prolongation

Interpretation:

Cardiac Resynchronization Pacing

Bi-ventricular pacing

This patient had ischaemic dilated cardiomyopathy with old ECGs showing same pacing morphology as seen here.
I've included the patient's chest x-ray below as we don't encounter many bi-vent pacemakers and I thought it was worth sharing.