The ECG represents the most useful diagnostic test for acute pericarditis. The electrocardiographic changes in acute pericarditis signify inflammation of the epicardium. There are 4 phases of electrocardiographic changes associated with acute pericarditis. Stage 1, in the first hours to days, is characterized by diffuse ST elevation (typically concave up). Associated atrial injury is reflected by elevation of the PR segment of the aVR lead, depression of the PR segment in other limb leads, and depression in the left chest leads (predominantly V5 and V6). Stage 2 is notable for resolution of the aforementioned stage 1 change and a return to a normal ECG. Stage 3 is characterized by diffuse T-wave inversions, commonly after the ST segments have become isoelectric. Stage 4 is typically a late reversion to a normal ECG. The characteristic ECG findings of acute pericarditis should be differentiated from the ECG changes of an ST-elevation myocardial infarction and an early repolarization pattern. A transthoracic echocardiogram may reveal a small amount of pericardial fluid, a nonspecific finding. A chest radiograph typically reveals a normal cardiac silhouette; an enlarged cardiac silhouette is apparent only with the accumulation of a large amount of fluid. Cardiac enzymes, including cTnI, may be modestly elevated in acute pericarditis.
Click here to return to the questions
Seminars in Medical Practice
Hospital Physician Board Review Manuals
Copyright © 2009, Turner White Communications
Updated 1/04/08 kkj