View source for Endocarditis

{{Infobox Disease |
  Name           = Endocarditis |
  Image          = Blood_culture_negative_endocarditis.jpg |
  Caption        = ''Bartonella henselae'' bacilli in cardiac valve of a patient with blood culture-negative endocarditis. The bacilli appear as black granulations. |
  DiseasesDB     = 4224 |
  ICD10          = {{ICD10|I|33||i|30}} |
  ICD9           = {{ICD9|421}} |
  ICDO           = |
  OMIM           = |
  MedlinePlus    = 001098 |
  eMedicineSubj  = emerg |
  eMedicineTopic = 164 |
  eMedicine_mult = {{eMedicine2|med|671}} {{eMedicine2|ped|2511}} |
  MeshID         = D004696 |
}}
'''Endocarditis''' is an [[inflammation]] of the inner layer of the [[heart]], the [[endocardium]]. It usually involves the [[heart valve]]s (native or prosthetic valves). Other structures which may be involved include the [[interventricular septum]], the [[chordae tendineae]], the mural endocardium, or even on intracardiac devices. Endocarditis is characterized by a prototypic lesion, the ''[[Vegetation (pathology)|vegetation]]'', which is a mass of [[platelets]], [[fibrin]], microcolonies of microorganisms, and scant inﬂammatory cells.<ref name=Harrison>{{cite book | author= Kasper DL, Brunwald E, [[Anthony Fauci|Fauci AS]], Hauser S, Longo DL, Jameson JL| title = [[Harrison's Principles of Internal Medicine]] | publisher = [[McGraw-Hill]] | year = 2005 | pages = 731–40 | month = May | isbn = 0-07-139140-1 | oclc = 54501403 56437106 56801936 56967424 }}</ref>  In the [[subacute]] form of infective endocarditis, the vegetation may also include a center of [[granuloma|granulomatous tissue]], which may fibrose or calcify.<ref name=Robbins>{{cite book |author=Mitchell RS, Kumar V, Robbins SL, Abbas AK, Fausto N |title=Robbins Basic Pathology |publisher=Saunders/Elsevier |edition= 8th |year=2007 |pages=406–8 |isbn=1-4160-2973-7}}</ref>

There are multiple ways to classify endocarditis. The simplest classification is based on [[etiology]]: either ''infective'' or ''non-infective'', depending on whether a [[microorganism]] is the source of the inflammation. Regardless, diagnosis of endocarditis is based on the clinical features, investigations such as [[echocardiogram]], as well as any [[blood culture]]s demonstrating the presence of endocarditis-causing microorganisms. 

==Infective endocarditis==
{{main|Infective endocarditis}}
Since the valves of the heart do not receive any dedicated blood supply, defensive immune mechanisms (such as [[white blood cell]]s) cannot directly reach the valves via the bloodstream. If an organism (such as [[bacterium|bacteria]]) attaches to a valve surface and forms a vegetation, the host immune response is blunted. The lack of blood supply to the valves also has implications on treatment, since drugs also have difficulty reaching the infected valve.

Normally, blood flows smoothly through these valves. If they have been damaged (from [[rheumatic fever]], for example) the risk of bacteria attachment is increased.<ref name=Robbins/>

== Non-infective endocarditis ==
Nonbacterial thrombic endocarditis (NBTE) or [[marantic endocarditis]] is most commonly found on previously undamaged valves<ref name=Robbins/>.  As opposed to infective endocarditis, the vegetations in NBTE are small, sterile, and tend to aggregate along the edges of the valve or the cusps<ref name=Robbins/>.  Also unlike infective endocarditis, NBTE does not cause an inflammation response from the body<ref name=Robbins/> (confusing, as the suffix "-itis" refers to inflammation).  NBTE usually occurs during a hypercoagulable state such as system wide bacterial infection, or pregnancy, though it is also sometimes seen in patients with venous catheters<ref name=Robbins/>.  NBTE may also occur in patients with cancers, particularly mucinous adenocarcinoma<ref name=Robbins/> where [[Trousseau syndrome]] can be encountered. Typically NBTE does not cause many problems on its own, but parts of the vegetations may break off and embolize to the heart or brain, or they may serve as a focus where bacteria can lodge, thus causing infective endocarditis<ref name=Robbins/>.

Another form of sterile endocarditis, is termed [[Libman-Sacks endocarditis]]; this form occurs more often in patients with [[lupus erythematosus]] and is thought to be due to the deposition of immune complexes<ref name=Robbins/>.  Like NBTE, Libman-Sacks endocarditis involves small vegetations, while infective endocarditis is composed of large vegetations<ref name=Robbins/>.  These immune complexes precipitate an inflammation reaction, which helps to differentiate it from NBTE.  Also unlike NBTE, Libman-Sacks endocarditis does not seem to have a preferred location of deposition and may form on the undersurfaces of the valves or even on the endocardium<ref name=Robbins/>.

Prognosis:
Features suggestive of a worse prognosis are Acute endocarditis (Staphylococcus aureus), heart failure, IV drug abuse (often left and right sided disease), prosthetic valve infection, infection of the aortic rather than mitral valve, associated rhythm disturbance. Subacute bacterial endocarditis (Streptococcus viridans) has a better prognosis.

==References==
{{Reflist|2}}

== External links ==
* [http://heartcenter.seattlechildrens.org/conditions_treated/endocarditis.asp Endocarditis information] from Seattle Children's Hospital Heart Center

{{Circulatory system pathology}}
{{Inflammation}}

[[Category:Valvular heart disease]]
[[Category:Inflammations]]
[[Category:Rat-carried diseases]]

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