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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Acute pericarditis | 1/3 | https://en.wikipedia.org/wiki/Acute_pericarditis | reference | science, encyclopedia | 2026-05-05T07:25:45.765948+00:00 | kb-cron |
Acute pericarditis is a type of pericarditis (inflammation of the sac surrounding the heart, the pericardium) usually lasting less than 4 to 6 weeks. It is the most common condition affecting the pericardium.
== Signs and symptoms ==
Chest pain is one of the common symptoms of acute pericarditis. It is usually of sudden onset, occurring in the anterior chest and often has a sharp quality that worsens with breathing in or coughing, due to inflammation of the pleural surface at the same time. The pain may be reduced with sitting up and leaning forward while worsened with lying down, and also may radiate to the back, to one or both trapezius ridges. However, the pain can also be dull and steady, resembling the chest pain in an acute myocardial infarction. As with any chest pain, other causes must also be ruled out, such as GERD, pulmonary embolism, muscular pain, etc. A pericardial friction rub is a very specific sign of acute pericarditis, meaning the presence of this sign invariably indicates presence of disease. However, absence of this sign does not rule out disease. This rub can be best heard by the diaphragm of the stethoscope at the left sternal border arising as a squeaky or scratching sound, resembling the sound of leather rubbing against each other. This sound should be distinguished from the sound of a murmur, which is similar but sounds more like a "swish" sound than a scratching sound. The pericardial rub is said to be generated from the friction generated by the two inflamed layers of the pericardium; however, even a large pericardial effusion does not necessarily present a rub. The rub is best heard during the maximal movement of the heart within the pericardial sac, namely, during atrial systole, ventricular systole, and the filling phase of early ventricular diastole. Fever may be present since this is an inflammatory process.
== Causes == There are several causes of acute pericarditis. In developed nations, the cause of most (80–90%) cases of acute pericarditis is unknown but a viral cause is suspected in the majority of such cases. The other 10–20% of acute pericarditis cases have various causes including connective tissue diseases (e.g., systemic lupus erythematosus), cancer, or involve an inflammatory reaction of the pericardium following trauma to the heart such as after a heart attack such as Dressler's syndrome. Familial Mediterranean fever and TNF receptor associated periodic syndrome are rare inherited autoimmune diseases capable of causing recurring episodes of acute pericarditis.
== Pathophysiology == Acute pericarditis is an over-arching term to describe a set of clinical symptoms and findings associated with inflammation of the pericardium. The initial triggering event is variable and depends on the underlying etiology. In general, an inflammatory stimulus (virus, idiopathic, radiation, surgery) results in an injury that activates the immune system of the body. A structure known as the inflammasome (a large molecule cellular structure) begins to activate other smaller inflammatory molecules known as cytokines that eventually attack and damage the mesothelial cells of the pericardium. The differentiation in symptoms and presentation may depend on the patient-level variation of the adaptive and innate immune system. If a patient has adequate mechanisms to turn off pro-inflammatory processes, the acute pericarditis may not progress. If immune system is not regulated as well and is allowed to continue activating the inflammasome to damage the mesothelial cells, this may lead to the inflammation of the pericardium. The goal of medical treatment for this condition is to turn off or regulate the patients inflammatory system.
== Diagnosis ==
For acute pericarditis to formally be diagnosed, two or more of the following criteria must be present: chest pain consistent with a diagnosis of acute pericarditis (sharp chest pain worsened by breathing in or a cough), a pericardial friction rub, a pericardial effusion, and changes on electrocardiogram (ECG) consistent with acute pericarditis. A complete blood count may show an elevated white count and a serum C-reactive protein may be elevated. Acute pericarditis is associated with a modest increase in serum creatine kinase MB (CK-MB). and cardiac troponin I (cTnI), both of which are also markers for injury to the muscular layer of the heart. Therefore, it is imperative to also rule out acute myocardial infarction in the face of these biomarkers. The elevation of these substances may occur when inflammation of the heart's muscular layer in addition to acute pericarditis. Also, ST elevation on EKG (see below) is more common in those patients with a cTnI > 1.5 μg/L. Coronary angiography in those patients should indicate normal vascular perfusion. Troponin levels increase in 35-50% of people with pericarditis. Electrocardiogram (ECG) changes in acute pericarditis mainly indicates inflammation of the epicardium (the layer directly surrounding the heart), since the fibrous pericardium is electrically inert. For example, in uremia, there is no inflammation in the epicardium, only fibrin deposition, and therefore the EKG in uremic pericarditis will be normal. Typical EKG changes in acute pericarditis includes