• 40 yom, presents to ED with suicidal ideation• On review of system by Psych resident, he

admits to mild CP earlier the same day• Code MI activated by ED

At first glance

• Wide and large R wave in V1• Q wave in lead I and aVL(we see a wide

negative deflection, called QS wave)• ST segment depression mostly seen in V1-V3

Q

Q

Wide and tall R

ST depression

• Looking for a tall/wide R wave in V1 and/or V2 should be a routine step in QRS analysis on every ECG

DDx of tall R wave in V1 or V2

1. RVH: right sided forces make R wave big in the right precordial leads (RVH will also have R axis)

2. RBBB (will also have wide QRS, RSR’)3. Posterior MI: posterior Q waves in V7-V9 are

“mirror “reflected as large R waves inV1-V34. WPW

• Normal variant if nothing on the ECG suggests the above 4 causes and QRS is normal

• In this pt, the tall R wave in V1-V3 may suggest posterior Q wave MI. The lateral Q waves suggest an associated lateral wall MI

• The ST depression in V1-V3 suggests posterior STEMI

Our pt has posterior STEMI/posterior Q wave MI??

On further analysis of the ECG

1. Short PR interval (<3 small boxes, ~100 ms)2. Wide QRS complex with delta wave *P is “riding” the upslope of R wave. *The upslope of R wave is slurred in lead V1 (this is

delta wave) Pre-excitation pattern=WPW pattern3. ST/T depression in V1-V3 is opposite in direction to

the abnormal QRS, and therefore, is likely secondary to the QRS abnormality/WPW

• Since this pt does not have any real angina and since he has all 3 features of WPW, his diagnosis is WPW rather than posterior MI

• In this context, the Q wave in leads I and aVL is actually a delta wave as well (a negative delta wave), not an MI

Q=negative delta

Q= negdelta

slur on the upslope of R=positive delta

ST depression 2dary to WPW

Pre-excitation/WPW pattern means that there is an accessory pathway (AP) that is conducting parallel to the AV node (AVN), creating the delta wave and the wide QRS.

Delta wave is positive in V1 when the accessory pathway is looking to the right, i.e., coming from the left

ECG of the same pt at another time. Conduction over the accessory pathway varies at different times. When the conduction over the accessory pathway slows down, which happens sometimes when AV conduction accelerates, QRS becomes narrower. ST/T become less depressed when QRS is “less” abnormal. Secondary St/T abnormality follows QRS abnormality