sinus rhythm
First Glance:
From across the room it looks like a wide sinus with some ST elevation in the upper trace
Discussion:
The upper lead is II and shows a P wave with a normal P axis, with around 2mm ST elevation (at a gain of 125%). The QRS axis is significantly abnormal with a deep S wave (suggestive of LAD), and almost 120ms. The lower ‘V’ lead has P wave morphology consistent with a septal lead, shows a broad R wave in a QRS that is slightly over 120ms, and has about a millimeter of ST depression at a gain of 160%. The R wave has a slight indentation, and with the long QRS interval this is consistent with a RBBB.
If the ST elevation in II was inferior ischemia, then the ST depression in the septal lead would be an expected reciprocal change. New RBBB could be caused by various coronary occlusions or stenoses.
And wait- is that a Q wave in the upper lead?
Nope- there is no Q in II. Notice that there is a small R that precedes the deep wide S waves. However, those deep S’s are abnormal (II is generally has a net-positive deflection/axis) and are suggestive of infarction.
All told, the minimal ST elevations seen only in the one lead, plus the non-ischemic (flat, not concave-up) ST morphology, plus the normal T waves might lean us away from an ischemic process. However, if these are new changes they are definitely not to be ignored.
Final Impression?
Sinus rhythm @ ~85 bpm with RBBB, possible LAFB. cant rule out infarction with active inferior ischemia.
Management implications:
Get 12L to evaluate properly for ischemic changes, axis deviation, and possible bifascicular block.
The Take-home Point:
When naming the deflections of the QRS be simple-minded. The first downwards deflection is called the Q. The first upwards deflection is called the R. The second downwards is called the S. If there is no R, then the solitary downwards deflection is called a ‘QS’.
It is tempting to call that big QS-looking thing in lead II a QS, but the existence of even the tiniest R before it means it is just an S wave. That doesn’t mean it can’t be infarction though!
One star strip. Students should identify the rhythm correctly.