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Archive for the ‘acute rheumatic fever’ Category

The pericarditis  of acute rheumatic fever is not a true infective pericarditis.It is more of inflammation .It is primarily  T cell mediated  reaction . Neutrophils rarely take part  in this inflammation and hence  no significant  exudation . Hence , there is less  sticky and adhesive molecules inside the pericardial space .The most inflamed layer is epicardium which a nothing but visceral  pericardium .This layer lacks the tensile strength to constrict the underlying myocardium.

why rheumatic pericarditis does not go for constrictionFor constriction to occur the fibrinous  ( thick ) layer of pericardium need to be involved . In rheumatic fever  even though it is  pancarditis ,  fibrous layer is not  involved. Further the inflammatory gradient is thought to spread from within  (Unlike tuberculosis )

Note :  In chronic tuberculous pericarditis,  diffuse inflammatory process  invade from the exterior surface . Very often ,  one can not differentiate  layers. In extreme cases even myocardium and pericardium can not be separated .

Summary

The peri-cardial effusion of acute rheumatic fever

  1. Is transient ,non infective and resolving (Unlike valvular inflammation !)
  2. Less of neutrophil activation  (Less adhesion)
  3. It does not involve the thick , tensile  fibrous layer of pericardium hence lacks the contractile force .

Other lingering  questions

1.How common is tamponade  in acute rheumatic fever ?

2.How important is the mass of the effusion (Viz  a Viz  Intra pericardial pressure !) in causing tamponade ?

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Cannon waves occur when Atria contracts against a closing tricuspid valve of  right ventricle .( There  would be a equivalent left atrial cannon which  goes into pulmonary vein as well  , it is discussed elsewhere !)

Cannon waves  happen only when P waves fall within QT interval in ECG as QT represents the electro-mechanical systole of  ventricles.  (Since P wave represents atrial systole , it is simple to understand when it falls within QT both atria and ventricular contractions collide to produce a cannon wave into the neck or pulmonary veins.)

The following two images of cannon waves  taken from the legend  Dr Paul woods own tracing  .

irregular cannon waves in jvp  complete heart block

regular cannon waves in jvp  svt avnrt  11 va conduction  002

Regular cannon waves

Occur during SVT  with 1:1 VA conduction.*

1 : 1  VA conduction  can be considered as  absence of  AV dissociation  (Rather  disciplined  VA association with every beat ) This is essential to create a hemodynamic  milieu for regular cannon waves.

* In AVNRT , VA conduction in strict  sense  is a misnomer  .It is simply a retrograde conduction thorough  the AV node .

Irregular cannon waves 

  1. Complete heart block .
  2. Multiple random VPDs
  3. Some patients with VT.*(Who are those patients ?  Those with AV dissociation when retrograde “P” wave falls  within QT interval cannon occurs. As expected this occurs in random fashion  which makes  the cannon fire irregular.

Can we get regular cannon in VT ?

Yes , but rare . As explained earlier this can happen only if AV  association occur on a retrograde fashion.

Further reading in this site

What-is-a-cannon-sound  , how is it related to cannon wave ?

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The answer is  simple . There is no  primary rheumatic myocardial dysfunction .The  LV dysfunction is related to the valvular lesion especially  mitral regurgitation. While this is 100 % true in chronic RHD , surprisingly  it holds good even in acute rheumatic fever as well  .(I have been thinking acute myocarditis is responsible for most cases of cardiac failure in Acute rheumatic fever !)
It is a paradox  to note  myocardits  being   a major  component in acute rheumatic fever (ARF) ,  still it does not persist  long term .It invariably resolves and the injury to the  valves goes on to result in progressive valve damage .
It is heartening to note this phenomenon in ARF  ,  as myocardial involvement behaves  just like joint involvement
Shall we modify  the famous statement  of the canadian Pathologist  William Boyd  Rheumatic fever licks  the joint but bites the heart”
Though ARF  bites the heart  , it  relishes only the valve  tissue and bites it harder ,  while  it simply  licks the myocardium   like the  joints
Is there a chronic indolent myocarditis ?
It was Initially thought there could be process of chronic myocardial inflammation.But now it is almost proven there is no entity like that .
But , it is not uncommon some patients with RHD present with significant LV dysfunction which in all probability unrelated to rheumatic activity .
Assignment for cardiology fellows .
1.Where in the heart  Ascoff bodies  are densely found ?
  1. Mainly over the valve leaflets
  2. Atrial muscle
  3. Ventricular myocardium
  4. Pericardium
2.Does Ascoff  bodies disappear  in  Chronic RHD ?
Reference

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Rheumatic valvulits , Valvular inflammation and edema  is the traditional answer .A detailed Echocardiographic study from All India Institute of medical sciences New Delhi  ,India  which was published in circulation 1996 answers this question most authentically .

From a meticulous  Echocardiographic  study of about 70 patients  (with both first and recurrent episodes of carditis ) the following findings were observed.

After reading this article one should be able to answer variety of  questions in RHD  such as

  • How common is MVPS in RHD ?
  • How often MR dissapear with Aspirin etc ?
  • Echocardiographic correlates  for care -coombs murmur ?

Reference

http://circ.ahajournals.org/content/94/1/73/T5.expansion.html

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While their cardiology colleagues are extravagantly indulging in coronary arteries   ,It is heartening to note the pediatricians our country has  silently come out with the first India specific  criteria for Acute Rheumatic fever diagnosis and management.

It was long over due . . . three cheers to them !

* It is ironical  these guidelines came in 2008,many of us are aware about the  existence  such guidelines , still  every one is after PTMC  for a full blown mitral stenosis !

http://www.indianpediatrics.net/pdf/acute_rheumatic_fever.pdf

Highlights and Summary

  • WHO criteria  of 2001 is adopted
  • ASO titre positivity alone has less value  in the diagnosis .Hence the importance of which is down graded
  • Steroids  are mandatory in all grades of carditis for 12 weeks
  • Benzathine  penicillin  should be administered weight  based and to be given  every 15 days in children less than 27 kg.

More high lights will be posted.

Secondary prophylaxis of  for Rheumatic fever

Note the Important advice regarding weight based penicillin prophylaxis.

 

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