Pericarditis
                          ============
þ Pericarditis vs. MI: EKG criteria
 - Classic teaching 
  + Diffuse ST-segment elevation 
   - May be localized rather than diffuse 
   - But no reciprocal ST-segment depression! (except perhaps in aVR and Vi) 
  + ST-segment elevation is concave upwards 
   - Beware that AMI may have similar ST-segment morphology ST-segment elevation 
     that is convex upwards or horizontal strongly favors AMI 
  + Additional pearl regarding ST-elevation 
   - ST^2 > ST^3 strongly favors acute pericarditis 
   - ST^3 > ST^2 verv strongly favors acute MI 
   - PR-segment depression (downsloping) 
   - Primarily present in viral pericarditis Often an early, transient finding 
 
 PR-segment elevation in aVR 
 May also be present in other diseases (e.g. AMI) 
 • Often absent in constrictive pericarditis 
 Chest pain tends to be positional, pleuritic 
 Beware that 16% of AMIs may present with positional or pleuritic pain! Factors strongly favoring acute pericarditis: pronoimced PR-segment depression (downsloping) in multiple leads; fiiction rub 
 Factors strongly favoring AMI: ST-segment elevation that is convex upwards; reciprocal ST-segment depression (in leads other than aVR and Vi); known new Qwaves 
 

þ Jeffrey Mann's take on the state of pericarditis knowledge:
  <pericar2.txt>

þ Who to send home:
 - pericarditis with no or minimal effusion, negative enzymes (no
   myocarditis)
 - Rosen's states:
   "Treatment and Disposition. Therapy of acute viral or idiopathic
   pericarditis consists of providing relief of symptoms. Analgesia can
   usually be obtained with a nonsteroidal antiinflammatory drug (NSAID)
   regimen, such as aspirin, ibuprofen, or indomethacin. Hospitalization
   should be reserved for those with severe or intractable pain, those in whom
   the diagnosis of MI cannot be excluded, and those patients with a
   pericardial effusion. Oral steroid therapy with prednisone is the mainstay
   of therapy for chronic pericarditis. IV methylprednisolone and colchicine
   have also been shown to be effective for recurrent pericarditis."
 - Braunwald's takes exception:
   "Initial observation in the hospital is warranted for almost all patients
   with acute pericarditis to exclude an associated myocardial infarction or a
   pyogenic process and to watch for the development of tamponade, which
   occurs in about 15 per cent of patients with acute pericarditis."

þ EKG changes of Pericarditis
 - The ECG undergoes 4 stages of change in most cases of viral pericarditis.
   The first stage is characterized by diffuse ST- segment elevation, normal
   T-waves, and PR-segment depression. In stage 2, the ECG transiently
   normalizes.  In stage 3, deep, symmetrical T-wave inversions develop.
   Finally, in stage 4 the ECG either normalizes, or the T-wave inversions
   permanently remain.
   Reference: Rosen 3rd ed. p 1395
 - usually PR depression, then later diffuse ST elevation, usually in all
   leads except aVR and V1
 - QRS voltage decreases if effusion
 - may have LOCALIZED EKG changes, suggestive of MI, in 5-10%.
 - Using the end of the P-R segment as baseline, if the apex of
   the T-wave is more than 4 times higher than the onset of the ST
   segment, early repolarization is likely.  Otherwise,
   pericarditis is more likely.
   [Marriott, Practical Electrocardiography 8th ed. p 519]
   [Chan TC, Brady WJ, Pollack M. Electrocardiographc
   manifestations: acute pericarditis. J Emerg Med 1999; 17(5):865-72.]
 - Exercise may restore the ST segments down to the baseline in
   patients with early repolarization, but this is unlikely to
   occur in acute pericarditis.
   [Marriott, Practical Electrocardiography 8th ed. p 519]

þ Ruling out other problems
 - can analyze the ST elevation in V6:
   ### get reference from Rich Maenza

þ Management of Pericarditis from Renal Failure
 - usually responds to NSAID plus more intensive dialysis [Scientific American
   Medicine, 4/97]