Saturday, November 01, 2008

Peripheral signs of infective endocarditis

I was recently asked by a student to explain on the pathogenesis of the peripheral signs of infective endocarditis.

I don't think anyone could adequately explain the exact pathogenetic mechanisms of these signs - many of which, the exact mechanisms remain unclear.

I found this particular article useful:
http://turner-white.com/pdf/hp_may00_endocard.pdf

And I have attempted to summarize the gist of that article below:

1. Roth's spot: Pathogenesis unclear

Severe potential mechanisms:
a. embolization of bacterial infiltrates from endocardium causing localized retinal abscesses
b. embolized bacterail infiltrates to retinal causing anoxia resulting in sudden increase in venous pressure, thus capillary rupture in the inner retinal layers

2. Osler's nodes Pathogenesis unclear

Few theories
1. Deposit of the septic microemboli from the endocardium
2. Nodes due to immunologically-mediated vasculitis caused by the circulating immune complexes.

3. Janeway lesion Pathogenesis unclear

Theories:
1. Necrotic microabscesses with an inflammatory infiltrate that involve the dermis but not the epidermis
2. Deposit of the septic microemboli from the endocardium

4. Splinter hemorrhage (this is a very non-specific sign - it can be due to many causes)

In IE, splinter hemorrhage is caused by the engorgement of the capillaries, resulting in hemorrhage. But what causes the engorgement and hemorrhage is not known

Some of the signs that I have seen in the most recent case of infective endocarditis:



In the second image, the lesions of the patient's palm were painless (Janeway lesions). A way to differentiate Osler's node from Janeway lesions is that Osler's node is pain, Janeway lesion is painless.

Another picture of Janeway lesion:


A picture of the Osler node can be found in this website: http://dermnetnz.org/systemic/osler.html

Infective endocarditis needs Duke criteria for diagnosis. The full table for Duke's criteria can be found in many standard textbooks and it is not intended to be reproduced here but a simple mnemonics to remember their principles is like this:

BE FEVEER
(*BE - Bacterial Endocarditis)

Major:
B = blood culture +ve >2 times 12 hr part

E = Endocardial involvement from Echo



Minor:
F = Fever

E = Echo findings (not fulfilling a major)

V = Vascular
findings
EE = Evidences from microbiological/immunology (2 evidences)

R = Risk factors/predisposing factors - drug abuse, valvular diseases

(Roth's spot - white centered hemorrhages)

9 comments:

Laura said...

Thanks so much for posting this - I'm a student at OSU and was just looking for a picture of Janeway lesions and found your page through Google. This is really helpful - it's so much easier to remember what signs are when I understand why they occur.

pelastikbintang said...

Dr. thx 4 this info =)

Anonymous said...

thank you!

Anonymous said...

Brilliant! Thank you very much! A grateful UK medical student :-)

cksheng74 said...

Thanks to everyone for visiting my blog :)

Fishydishy said...

Hi,
Again thanks. I was looking for some pictures to fix what the lesions look like. Could I add this as an additional and original aide memoire.

Peripheral lesions = Janeway's Rose
Roth Spots,
Osler's Nodes,
Splinter Hemorrhages
Embolic Phenomena

Roses have thorns so can be painful hence Osler's Nodes are the painful ones and often get you on the fingertips. Janeway Lesions are then the non-painful ones.

cksheng74 said...

@Fishydishy, thank you for your comment. That's a catchy mnemonic. Very useful :)

Anonymous said...

Funny - I'm a student at OSU now and just saw the post when I searched for "osler's nodes mnemonic"

David Russell said...

I am a medical transcriptionst and wondered why splinter's, Osler's and Janeway's were presented as they were when transcribing the Skin exam. Your blog answered my question and thank you!
David

COPYRIGHT NOTICE

PLEASE NOTE: All contents in this blog are copyrighted materials, unless otherwise stated. Even if you encounter materials in this page without a copyright notice, it does not mean that it is not copyrighted (Click here to read TEN BIG myths on copyright explained). This is especially so as most nations are signatories of the Berne Convention on international copyright law (World Intellectual Property Organization). Nevertheless, I have licensed almost all the materials contained here under Creative Commons licenses strictly for educational, non-commercial purposes only. Kindly email me at cksheng74@yahoo.com should you want to use any of the materials for commercial purposes. Thank you.