Editing Pericarditis (section)

==Diagnosis==

[[File:PericarditisMyocarditis.jpg|thumb|upright=1.5|Diffuse ST elevation in a young male due to myocarditis / pericarditis]]
[[File:PericarditisECG.JPG|thumb|upright=1.5|An ECG showing pericarditis. Note the [[ST elevation]] in multiple leads with slight reciprocal [[ST depression]] in aVR.]]

The preferred initial diagnostic testing is the ECG, which may demonstrate a 12-lead [[electrocardiogram]] with diffuse, non-specific, concave ("saddle-shaped"), ST-segment elevations in all leads except aVR and V1<ref name=mk /> and PR-segment depression possible in any lead ''except aVR'';<ref name=mk /> sinus tachycardia, and low-voltage QRS complexes can also be seen if there is subsymptomatic levels of pericardial effusion. The PR depression is often seen early in the process as the thin atria are affected more easily than the ventricles by the inflammatory process of the pericardium.{{citation needed|date=February 2021}}

Since the mid-19th century, [[retrospective diagnosis]] of pericarditis has been made upon the finding of adhesions of the pericardium.<ref>{{Cite journal| first = Austin | last = Flint | name-list-style = vanc |year=1862|title=Lectures on the diagnosis of diseases of the heart: Lecture VIII|journal=American Medical Times: Being a Weekly Series of the New York Journal of Medicine|volume=5|issue=July to December|pages=309–311}}</ref>

When pericarditis is diagnosed clinically, the underlying cause is often never known; it may be discovered in only 16–22 percent of people with acute pericarditis.{{citation needed|date=March 2014}}

===Imaging===
<gallery>
File:PericardialeffusionUS.PNG|Ultrasounds showing a pericardial effusion in someone with pericarditis
File:PericardialeffusionCXR.PNG|A pericardial effusion as seen on CXR in someone with pericarditis
</gallery>

On MRI [[MRI sequence#T1 and T2|T2-weighted spin-echo]] images, inflamed pericardium will show high signal intensity. [[Cardiac magnetic resonance imaging#Late gadolinium enhancement|Late gadolinium contrast]] will show uptake of contrast by the inflamed pericardium. Normal pericardium will not show any contrast enhancement.<ref>{{cite journal | vauthors = Ismail TF | title = Acute pericarditis: Update on diagnosis and management | journal = Clinical Medicine | volume = 20 | issue = 1 | pages = 48–51 | date = January 2020 | pmid = 31941732 | pmc = 6964178 | doi = 10.7861/clinmed.cme.20.1.4 }}</ref>

===Laboratory test===
Laboratory values can show increased blood urea nitrogen ([[Blood urea nitrogen|BUN]]), or increased blood [[Serum creatinine|creatinine]] in cases of [[uremic pericarditis]]. Generally, however, laboratory values are normal, but if there is a concurrent myocardial infarction (heart attack) or great stress to the heart, laboratory values may show increased cardiac markers like [[Troponin]] (I, T), [[CK-MB]], [[Myoglobin]], and [[Lactate dehydrogenase|LDH]]1 (lactase dehydrogenase isotype 1).{{citation needed|date=February 2021}}

===Classification===
Pericarditis can be classified according to the composition of the fluid that accumulates around the heart.<ref>{{cite web | first =  Edward C. | last = Klatt | name-list-style = vanc | url = http://library.med.utah.edu/WebPath/CVHTML/CVIDX.html | title = Cardiovascular Pathology Index Images | work = The Internet Pathology Laboratory for Medical Education | publisher = Florida State University College of Medicine | archive-url = https://web.archive.org/web/20070524224731/http://library.med.utah.edu/WebPath/CVHTML/CVIDX.html | archive-date=2007-05-24 }}</ref>

Types of pericarditis include the following:{{citation needed|date=October 2021}}
* [[serous]]
* [[purulent]]
* [[Uremic pericarditis|fibrinous]]
* [[caseous]]
* [[hemorrhagic]]

====Acute vs. chronic====
Depending on the time of presentation and duration, pericarditis is divided into "acute" and "chronic" forms. [[Acute pericarditis]] is more common than chronic pericarditis, and can occur as a complication of infections, immunologic conditions, or even as a result of a heart attack (myocardial infarction), as [[Dressler's syndrome]]. Chronic pericarditis however is less common, a form of which is [[constrictive pericarditis]]. The following is the clinical classification of acute vs. chronic:{{citation needed|date=February 2021}}
* ''Clinically'': Acute (<6 weeks), Subacute (6 weeks to 6 months) and Chronic (>6 months)