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Department: Heart Beats

MI mimickers

Acute pericarditis

Barto, Donna DNP, RN, CCRN

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doi: 10.1097/01.CCN.0000436381.67253.30
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In Brief

A 50-year-old woman is admitted to the ED complaining of sharp chest pain that's more severe when she lies down, takes a deep breath, or coughs. She states that her chest pain decreases in intensity when she sits up and leans forward. Her vital signs are as follows: BP: 140/80; heart rate: 110/minute, sinus tachycardia; respiratory rate: 18/minute, unlabored.

A 12-lead ECG is obtained (see Initial 12-lead ECG), and because the patient has new onset chest pain associated with ST segment elevation, she was taken to the cardiac catheterization lab. Coronary arteriography demonstrated no hemodynamically significant coronary artery stenoses. What could be the cause of her chest pain and ST segment elevation?

Acute pericarditis is a condition in which the sac that encloses the heart, the pericardium or pericardial sac, becomes inflamed. This sac is composed of two thin layers of tissue called the visceral and parietal layers. Between the two layers is a small amount of fluid designed to keep the visceral and parietal layers from rubbing against each other. Although an underlying cause of most patients' pericarditis isn't identified and therefore considered idiopathic, potential causes of this inflammatory process include:

  • autoimmune diseases (such as lupus)
  • metabolic disorders (such as uremia)
  • malignancy
  • any kind of infection (such as viral)
  • cardiac disorders (such as post-cardiac surgery and post-myocardial infarction).
F1-2
Figure:
Initial 12-lead ECG

The clinical presentation of a patient with pericarditis is similar to a patient with acute coronary syndromes (ACS) in that chest pain is present. The pain is generally sharp and located in the precordial area. It can also radiate to the neck, left shoulder, and left arm. One differentiating feature from ACS is that the pain associated with pericarditis is usually positional in nature—the patient states the pain worsens when lying down,taking a deep breath, or coughing. Leaning forward while sitting may alleviate the pain associated with pericarditis.1 Other signs and symptoms of pericarditis are low-grade fever, dyspnea, tachypnea, and malaise. A pericardial friction rub with a superficial scratchy or squeaking quality may be auscultated and is a good indication that the patient has pericarditis.2

ECG changes associated with pericarditis include ST segment elevation, which is more “diffuse” compared to the anatomical groupings in ACS. ST segment elevation in multiple EKG leads, especially in patients who are clinically stable, points toward a diagnosis of pericarditis over ACS.3 The ST segment elevation may also be concave or saddle-shaped, which is a feature often attributed to pericarditis, but not specific to the condition.4

Other ECG features noted in patients with pericarditis include reciprocal ST segment depression in leads aVR and V1,PR segment elevation in lead aVR, and PR segment depression in the other limb leads and left chest leads, primarily V5 and V6.4 Another ECG characteristic of pericarditis is the presence of PR segment depression in leads with the ST segment elevation.

A review of this patient's ECG shows ST segment elevation in almost all of the leads except for aVR and V1. The ST elevation is concave in appearance. There's PR segment depression in the leads with ST segment elevation. Based on her cardiac catheterization report that demonstrated normal coronary arteries, it was determined that acute pericarditis was the cause of her abnormal ECG and chest pain. Since this patient's lab tests all came back normal, the cause of her disease was determined to be idiopathic. She was treated in the outpatient setting with nonsteroidal anti-inflammatory drugs for 2 weeks. High-dose aspirin is also considered a first-line therapy for patients with post-myocardial infarction pericarditis. If nonsteroidal anti-inflammatory drugs aren't effective, colchicine can be added as adjunctive therapy. Glucocorticoids may be considered in those refractory to the first-line drugs. Medical management would also include treating the underlying cause of pericarditis, if it's known.

REFERENCES

1. Bradbury-Golas K, Campo T, Chiccarine A. Getting to the heart of back and shoulder pain. Advanced Emergency Nursing Journal. 2010;32(2):127–134.
2. Hardegree EL, Bell MR. 84-year-old woman with chest pain. Mayo ClinicProc. 2012;87(7):700–703. http://dx.doi.org/10.1016/j.mayocp.2012.03.015.
3. Pollak P, Brady W. Electrocardiographic patterns mimicking ST segment elevation myocardial infarction. Cardiol Clin. 2012;30(4):601–615.
4. Hannibal GB. ECG characteristics of acute pericarditis. AACN Adv Crit Care. 2012;23(3):341–344.
5. Spangler S, Fredi J. Acute Pericarditis. 2013. http://emedicine.medscape.com/article/156951-overview.
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