Chapter 9-5: Acute Pericarditis

TEXTBOOK PRESENTATION

Acute pericarditis typically presents in young adults, with 1 week of viral symptoms and chest pain that improves with leaning forward. Physical exam reveals a 3-part friction rub. ECG reveals ST elevations and PR depressions in all leads.

DISEASE HIGHLIGHTS

1. Differential diagnosis

   1. Viral pericarditis is primarily caused by coxsackievirus, echovirus, and adenovirus.

   2. Other infectious causes of pericarditis include TB (historically the most common) and HIV.

   3. Pericarditis may occur after myocardial injury (post MI and postcardiac surgery).

   4. Rheumatologic causes include systemic lupus erythematosus and rheumatoid arthritis.

   5. Procainamide and hydralazine are among the drugs that can cause pericarditis.

   6. Malignancy that has metastasized to the pericardium

   7. Chest irradiation

   8. Uremia

2. Although the differential diagnosis of pericarditis is long, 85–90% of cases are considered idiopathic or due to an undiagnosed virus.

EVIDENCE-BASED DIAGNOSIS

1. Pericarditis is diagnosed when the characteristic pericardial friction is heard or when a patient with chest pain has characteristic ECG findings.

2. History

   1. Chest pain is almost always present.

   2. The pain is usually pleuritic.

   3. It classically radiates to the trapezius ridge.

   4. Pain improves with sitting and worsens with reclining.

3. Physical exam

   1. The pericardial friction rub is insensitive but nearly 100% specific; it is diagnostic of pericarditis.

   2. The rub is usually triphasic.

      1. Triphasic in 58% of cases

      2. Biphasic in 24% of cases

      3. Monophasic in 18% of cases

   3. Pericarditis is usually complicated by a pericardial effusion. Although the physical exam is insensitive for pericardial effusions, it is good for detecting tamponade.

      1. Sensitivity of jugular venous distention to detect tamponade is 100%.

      2. Sensitivity of tachycardia to detect tamponade is 100%.

      3. Pulsus paradoxus > 12 mm Hg

         1. Sensitivity, 98%; specificity, 83%

         2. LR+, 5.9; LR−, 0.03

      4. Beck triad (hypotension, jugular venous distention, and the presence of muffled heart sounds) is seldom seen but is very specific for tamponade.

   4. ECG

      1. The ECG most commonly shows widespread ST elevations and PR depressions. This finding is highly specific, but the sensitivity is only about 60%.

      2. The differentiation of pericarditis from acute MI on ECG can be difficult. Some of the key differentiating factors are

         1. ST elevation in pericarditis is usually diffuse while in MI it is localized to leads associated with the area of ischemia/infarction.

         2. ST elevations in MI are often associated with reciprocal changes.

         3. PR depression is very uncommon in acute MI.

         4. Q waves are not present with pericarditis.

   Pericarditis can mimic MI. The presence of a rub and careful analysis of the ECG should enable their distinction.

   5. Other diagnostic tests

      1. An echocardiogram is always done when pericarditis has been diagnosed to evaluate the presence of a significant pericardial effusion and exclude the presence of tamponade.

      2. Cardiac enzymes are frequently positive and are therefore not helpful for distinguishing the chest pain of pericarditis from that of cardiac ischemia.

4. Determining the etiology of pericarditis

   1. Because most pericarditis is either idiopathic or viral, requiring only supportive care, extensive work-up is generally not indicated.

   2. After a thorough history, ...