Final answer:
Pericarditis typically appears as widespread ST-segment elevation on a 12-lead ECG, which helps differentiate it from conditions like myocardial infarction where ST elevation is more localized.
Step-by-step explanation:
Pericarditis on a 12-lead ECG is typically characterized by widespread ST-segment elevation. This condition represents inflammation of the pericardium, the fibrous sac surrounding the heart. The elevation of the ST segment in pericarditis is generally concave upwards and present in multiple leads. The ST elevation in a 12-lead ECG is a key diagnostic criterion, distinguishing pericarditis from myocardial infarction, where ST elevation is usually more localized. It is important for healthcare professionals to recognize these ECG patterns to ensure accurate diagnosis and treatment.