Pericarditis

Definition and Overview

Etiology

Pathophysiology

• Edema and thickening of the parietal layer
• Production of exudative pericardial fluid
• Increased friction between layers (causing the rub)

• Fibrinous/fibrinopurulent - viral/uremic (shaggy, "bread-and-butter" appearance)
• Suppurative/purulent - bacterial (pus formation)
• Caseous - tuberculous
• Hemorrhagic - malignancy

Gross pathology: Acute suppurative pericarditis - note the shaggy, exudative pericardial surface (Robbins Pathology)

Clinical Presentation

Symptoms

• Chest pain - sharp, pleuritic, retrosternal; worsened by lying supine, deep inspiration, and swallowing; relieved by sitting forward
• Radiation to the trapezius ridge or back (characteristic - from phrenic nerve involvement)
• Low-grade fever and myalgias
• Dyspnea

Signs

• Pericardial friction rub - pathognomonic, present in ~1/3 of cases
  • Best heard: lower left sternal border, patient leaning forward in full expiration
  • Classic rub = 3 components (ventricular systole + early diastole + atrial contraction), described as "walking on crunchy snow"
  • Evanescent and intermittent - may require repeated auscultation
• Low-grade fever (<38°C), sinus tachycardia
• Atrial fibrillation/flutter in ~5%

Diagnostic Criteria

1. Characteristic chest pain (positional/pleuritic)
2. Pericardial friction rub
3. ECG changes
4. New or worsening pericardial effusion

ECG Changes (4 classic stages)

Laboratory Testing

• CRP/ESR/WBC - elevated; CRP is the best marker for activity and guides treatment duration
• Troponin - mildly elevated in ~30% (myopericarditis); significant elevation suggests concurrent myocarditis
• BUN/Cr - check for uremia
• ANA, rheumatoid factor if autoimmune etiology suspected
• Blood cultures, PPD/IGRA if infectious etiology suspected

Imaging

• Chest X-ray - often normal in uncomplicated pericarditis; "water-bottle" cardiac silhouette if large effusion (>250 mL)
• Echocardiography - should be performed in all cases; detects effusion, wall motion abnormalities (myocarditis), tamponade physiology
• Cardiac MRI - gold standard for detecting pericardial inflammation (gadolinium enhancement); defines extent of involvement and differentiates pericarditis from myocarditis

High-Risk Features (Hospitalize)

• Fever >38°C
• Subacute onset
• Large pericardial effusion or cardiac tamponade
• Failure to respond to NSAIDs after 1 week
• Myocarditis (elevated troponin)
• Immunocompromised state
• Trauma
• Oral anticoagulant use
• Pregnancy

Treatment

Acute/Idiopathic Pericarditis

• NSAID + colchicine is the recommended combination - colchicine significantly reduces recurrence
• Taper only when asymptomatic AND CRP normalized
• Gastric protection (PPI) with NSAIDs

• Impair clearance of infectious agents
• Increase risk of recurrence
• Reserved for: NSAID/colchicine failure or contraindications, autoimmune disease, renal failure, pregnancy
• If used: low dose prednisone 0.2-0.5 mg/kg/day, taper over 6-12 weeks guided by symptoms and CRP; concurrent colchicine recommended

Specific Causes

• Uremic pericarditis: intensive dialysis + NSAIDs (indomethacin 25 mg TID); steroids for refractory cases
• Post-MI (early): aspirin (preferred; avoid ibuprofen which affects infarct healing)
• Dressler syndrome: NSAIDs (ibuprofen 600 mg QID or indomethacin 25 mg TID); discontinue anticoagulants if possible
• Tuberculous pericarditis: antituberculous therapy + corticosteroids to reduce constrictive pericarditis risk
• Bacterial/purulent: IV antibiotics + urgent pericardial drainage
• Activity restriction: until asymptomatic + CRP normal (athletes: minimum 3 months)

Recurrent Pericarditis

• Occurs in 15-30% of idiopathic cases
• Definition: new episode after a symptom-free interval of ≥4-6 weeks with objective evidence of recurrence (rub, ECG changes, new effusion, elevated CRP)
• Treatment: repeat NSAID + colchicine (same doses)
• Refractory recurrences: corticosteroids ("triple therapy"); anakinra (IL-1 blocker) shown effective in corticosteroid-dependent recurrent pericarditis
• Recurrences have not been associated with evolution to constrictive pericarditis in idiopathic cases

Complications

Cardiac Tamponade (emergency)

• Beck's triad: hypotension + elevated JVP + muffled heart sounds
• Pulsus paradoxus >10 mmHg
• ECG: electrical alternans
• Treatment: urgent pericardiocentesis

Constrictive Pericarditis

• Dense fibrous scarring obliterates pericardial space
• Right-sided venous distension + low cardiac output (similar to restrictive cardiomyopathy)
• Kussmaul sign (JVP rises on inspiration)
• Treatment: pericardiectomy

Special Situations

Myopericarditis

• Up to 15% of pericarditis cases have concurrent myocarditis
• Elevated troponin, wall motion abnormalities on echo
• Cardiac MRI confirms myocardial involvement
• Strict activity restriction; avoid competitive sports for at least 3-6 months

Pericarditis in Autoimmune Disease

• SLE: typically complicates disease flare; polyserositis; clinically significant tamponade in only 1-2%
• RA: clinically significant pericarditis in only 1-2%; constrictive pericarditis can develop over months; aggressive DMARD/biologic therapy appears to reduce incidence
• SSc: small pericardial effusions common, rarely hemodynamically significant; large rapidly accumulating effusions occasionally occur with dSSc

Dry (Fibrinous) Pericarditis and Pericardial Effusion

PART 1 - DRY (FIBRINOUS) PERICARDITIS

What Is "Dry" Pericarditis?

Pathophysiology

Fig. 3.13 Fibrinous pericarditis. (A) Gross: shaggy fibrin deposits coating the pericardium. (B) Histology: pink fibrin meshwork (F) overlies the pericardial surface (P). - Robbins & Cotran Pathologic Basis of Disease

Causes of Fibrinous/Dry Pericarditis

• Viral/idiopathic - most common; coxsackievirus B, echovirus, adenovirus, EBV, CMV, HIV
• Uremia - classic cause; fibrinous exudate is the hallmark
• Acute MI - early post-infarction (epistenocardiac) pericarditis, 2-4 days after transmural infarction
• Rheumatic fever - fibrinous pericarditis as part of pancarditis; resolves without residua
• Autoimmune - SLE, RA, scleroderma

Clinical Features of Dry Pericarditis

• Sharp, pleuritic, retrosternal
• Worsened by lying flat (supine), deep inspiration, and swallowing
• Relieved by sitting forward/leaning forward
• May radiate to the trapezius ridge (phrenic nerve involvement) - highly specific for pericarditis

• Results from friction between inflamed/fibrinous visceral and parietal pericardial surfaces (and sometimes parietal pericardium vs adjacent pleura)
• Classic rub = 3 components: ventricular systole + early diastole + atrial contraction ("crunchy snow" sound)
• Best heard at the lower left sternal border, patient leaning forward in full expiration
• Evanescent and intermittent - requires repeated auscultation
• Importantly: no correlation exists between the size of any effusion and the presence of a rub - a loud rub does not mean no effusion, and an absent rub does not rule out pericarditis

• PR depression in multiple leads is the most specific ECG sign
• Distinction from STEMI: diffuse (not focal), concave ST elevation, PR depression, no reciprocal ST depression (except in aVR and V1)

Fate of Fibrinous Exudate

1. Resolution - fibrinolysis dissolves the exudate; macrophages clear it - no sequelae (most common)
2. Organization - fibroblasts and blood vessels grow into fibrin; leads to fibrous scarring - potentially constrictive pericarditis

PART 2 - PERICARDIAL EFFUSION

Definition and Normal Values

Classification

• Acute vs subacute vs chronic (>3 months)

Causes

• Viral/idiopathic pericarditis - most common cause overall
• Malignancy - lung, breast, lymphoma; often bloody; large effusions; irregular/nodular pericardium on CT/MRI
• Uremia - large effusions possible; rarely hemodynamically significant unless on inadequate dialysis
• Trauma - hemopericardium
• Aortic dissection - hemopericardium; life-threatening (pericardiocentesis is CONTRAINDICATED - may worsen dissection)
• Post-MI wall rupture - sudden hemopericardium; surgical emergency
• Autoimmune diseases - SLE (1-2% develop tamponade), RA, SSc
• Radiation - post-mediastinal irradiation
• Hypothyroidism (myxedema) - large, slowly accumulating transudates; rarely cause tamponade
• Heart failure - transudative effusion
• Post-cardiac surgery / post-pericardiotomy syndrome
• Bacterial/TB - purulent; high risk of tamponade and constriction

Clinical Presentation

• Dull chest ache, pressure
• Dyspnea, cough (compression of adjacent structures)
• Hiccups (phrenic nerve compression)
• Hoarseness (recurrent laryngeal nerve compression)

Investigations

• Normal until effusion >200-250 mL
• "Water-bottle" (flask) sign - enlarged, globular cardiac silhouette with acute cardiophrenic angles
• Bilateral hilar overlay sign
• Epicardial fat pad sign (lateral view): a band of higher density (fluid) sandwiched between two bands of lower density (epicardial fat posteriorly + mediastinal fat anteriorly) - the "sandwich sign"
• Rapid change in cardiac silhouette size on serial CXRs should raise strong suspicion
• Notably: no change in pulmonary vascular pattern (distinguishes from heart failure)

• Echolucent (echo-free) space surrounding the heart
• Small effusions: visible only posterior to the LV
• Moderate-large: circumferential
• Distribution is non-uniform due to gravity - most commonly along the posterolateral LV wall, inferolateral to the RV, and in the superior pericardial recess
• Pericardial thickening: increased echogenicity on 2D; multiple parallel posterior reflections on M-mode
• Limitation: cannot reliably characterize fluid type by echo appearance; anterior loculated effusions may be missed

POCUS parasternal long axis view: the pericardial effusion (dark echo-free space) is visible superior to the LV, with the pericardium and descending aorta labeled - Rosen's Emergency Medicine

• Better than echo for loculated or anterior effusions, overall sizing, and pericardial thickening
• Effusion appears as low-attenuation fluid surrounding the heart
• MRI:
  • Transudates/exudates without debris: T1 hypointense, T2/SSFP hyperintense
  • Proteinaceous or hemorrhagic effusions: T1 hyperintense
  • Pericardial inflammation: gadolinium enhancement of pericardium
  • Gold standard for characterizing effusion type, pericardial thickening, and inflammatory activity

• Rarely diagnostic unless infection is suspected
• Exudate vs transudate (Light's criteria)
• Cell count/differential, culture, cytology (malignancy), ADA (TB)
• Immune complexes, ANA, anti-dsDNA in autoimmune disease

Cardiac Tamponade - When Effusion Becomes Life-Threatening

• Rising pericardial pressure compresses all chambers
• RV compresses first (lower pressure) - RV diastolic collapse (earliest echocardiographic sign)
• Then RA compresses - RA systolic collapse
• Ventricular interdependence is exaggerated: inspiration fills RV more (shifts septum left, reducing LV filling) - produces pulsus paradoxus

1. Hypotension
2. Elevated JVP (distended neck veins)
3. Muffled heart sounds

• Tachycardia (compensatory)
• Pulsus paradoxus >10 mmHg (exaggerated fall in systolic BP on inspiration)
• Kussmaul sign is typically absent in tamponade (it is present in constriction)

1. RA systolic collapse (most sensitive)
2. RV diastolic collapse (most specific)
3. IVC plethora (dilated IVC, <50% collapse with inspiration)
4. Respiratory variation in mitral/tricuspid inflow >25-40% (Doppler)

• Subxiphoid approach most common
• If hemopericardium from aortic dissection: do NOT drain - surgical repair is required
• If purulent: pericardiectomy or catheter drainage with lavage + fibrinolytics + IV antibiotics

Treatment of Pericardial Effusion (Without Tamponade)

Relationship Between Dry Pericarditis and Pericardial Effusion

Dry/Fibrinous Pericarditis
        ↓ (if inflammation persists or worsens)
Effusive Pericarditis (pericardial effusion develops)
        ↓ (if large/rapid accumulation)
Cardiac Tamponade
        ↓ (if extensive fibrosis)
Constrictive Pericarditis

• Most patients with pericarditis have at least a small effusion at some point, even if clinically "dry"
• A rub does NOT exclude an effusion, and an effusion does NOT exclude a rub
• The progression from dry to effusive to constrictive depends on the etiology - idiopathic/viral cases rarely progress to constriction (0.48%), while TB and bacterial cases have high risk