What is the pathophysiology of pericarditis?

Pathophysiology of Pericarditis

Pericarditis develops through direct tissue injury followed by immune-mediated inflammation, with the specific mechanism varying by etiology—viral infections cause direct cytolysis and subsequent autoimmune activation, while bacterial, autoimmune, and post-injury forms trigger inflammation through distinct pathways that determine both clinical course and risk of progression to constriction. 1

Viral and Idiopathic Mechanisms

• Cardiotropic viruses initiate pericardial inflammation through direct cytolysis of pericardial cells, followed by immune-mediated injury that perpetuates the inflammatory response 1
• This two-phase process explains why viral pericarditis often has a self-limited course but can recur in 15-30% of cases when the immune response becomes dysregulated 2
• The low risk of constrictive pericarditis (<1%) in viral/idiopathic cases reflects the typically transient nature of inflammation 2, 1

Bacterial Pathophysiology

• Bacterial pericarditis, particularly tuberculous and purulent forms, causes severe inflammation with retention of toxic metabolites that leads to extensive fibrosis 2
• This aggressive inflammatory cascade explains the dramatically elevated 20-30% risk of progression to constrictive pericarditis 2, 1
• Tuberculosis triggers granulomatous inflammation with caseous necrosis, while purulent bacteria cause direct suppurative destruction of pericardial tissue 1

Autoimmune Mechanisms

• Systemic autoimmune diseases trigger pericardial inflammation through autoreactive T-cell activation and production of anti-heart antibodies 1
• The pericardial involvement typically reflects the overall disease activity of the underlying condition (lupus, rheumatoid arthritis, systemic vasculitides) 2
• These cases carry an intermediate 2-5% risk of constriction, reflecting chronic but less destructive inflammation compared to bacterial causes 2, 1

Post-Cardiac Injury Pathophysiology

• Post-cardiac injury syndromes develop through an autoimmune mechanism triggered by initial tissue damage—whether from myocardial necrosis, surgical trauma, or iatrogenic injury—with pericardial bleeding and pleural incision serving as key triggers 2
• The latent period of several weeks between injury and symptom onset, plus the response to anti-inflammatory therapy, confirms the immune-mediated nature 2
• Dressler syndrome (post-MI pericarditis) has become rare with early reperfusion but can still occur with even minor pericardial bleeding 2

Uremic Pathophysiology

• Uremic pericarditis results from retention of toxic metabolites in renal failure, with pericardial effusions often becoming bloody 2
• The incidence of hemodynamically significant effusions has decreased with advanced renal replacement therapy 2

Progression to Constriction

• Constrictive pericarditis develops when chronic inflammation causes impaired diastolic filling due to pericardial fibrosis and thickening, though 20% of cases occur with normal pericardial thickness 2
• The delay between initial inflammation and onset of constriction is variable and represents direct evolution from subacute/chronic pericarditis 2
• Advanced cases may develop myocardial fibrosis or atrophy, adding systolic dysfunction to the hemodynamic impairment 2

Recurrence Mechanisms

• Recurrent pericarditis often reflects inadequate initial treatment or immune-mediated perpetuation of inflammation, with corticosteroid use paradoxically favoring recurrence despite providing rapid symptom control 2
• The recurrence rate increases from 15-30% after initial episodes to 50% after first recurrence in patients not treated with colchicine 2