12-LEAD ECG's - A "Web Brain" for Easy Interpretation

Pericarditis

Pericarditis is often a difficult clinical entity to detect. Recognition of acute pericarditis can be facilitated by thinking of diagnosis as a 3 part process:

1. History

   • Inquire about preceding viral illness.

    

2. Physical exam

   • Hearing a pericardial friction rub is the most diagnostic sign!

    

3. ECG findings

   • These are divided into 4 stages. The easiest way to remember these sequential changes is to conceptualize the four stages as follows:
     

     Stage I
     everything is UP (i.e., ST elevation in almost all leads - see below)

     Stage II
     Transition ( i.e., "pseudonormalization").

     Stage III
     Everything is DOWN (inverted T waves).

     Stage IV
     Normalization.

Note how, in the tracing of Stage I pericarditis (figure right), the ST segment elevation is diffuse ("everything up" stage), with elevation being seen in virtually all leads except those "far away" (shaded leads aVR, V1, III).

Early Repolarization

The distinction between the ST elevation of Stage I pericarditis, that which is seen in early repolarization, and acute MI can usually be made because early repolarization is most often seen in otherwise healthy young adults. ST elevation is usually localized to one (or at most two) areas of the heart.

Acute MI

Acute MI is usually suggested by the history (older patient with risk factors; chest pain more constant and severe).  The ECG may show Q waves, reciprocal ST depression and T wave inversion, while the ST segment is still elevated. In contrast, with pericarditis the T wave typically does not invert until after the ST segment has returned to the baseline.
 

	12-LEAD ECG's - A "Web Brain" for Easy Interpretation