What cardiac issue causes pleural effusions?

Heart Failure is the Primary Cardiac Cause of Pleural Effusions

Heart failure is the most common cardiac cause of pleural effusions, resulting from increased pulmonary capillary pressure that leads to fluid accumulation in the pleural space. 1, 2

Pathophysiology of Heart Failure-Related Pleural Effusions

• Heart failure causes pleural effusions through elevated pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP), leading to increased interstitial fluid in the lungs that eventually accumulates in the pleural space 2
• Higher PCWP (odds ratio 1.06) and CVP (odds ratio 1.09) are independently associated with the presence of pleural effusions in heart failure patients 2
• The salt-avid state in heart failure leads to expansion of intravascular volume followed by extravascular fluid accumulation, including pleural effusions 3
• Low serum albumin levels in heart failure patients further contribute to pleural fluid formation due to decreased oncotic pressure 2

Diagnostic Features of Heart Failure-Related Pleural Effusions

• While typically bilateral, heart failure-related pleural effusions can be unilateral in up to 41% of cases 4, 1
• When unilateral, right-sided effusions are more common than left-sided 5
• Pleural fluid characteristics:
  • Usually transudative by Light's criteria 5
  • However, 20-25% may appear exudative despite being caused by heart failure 6
  • Serum-to-pleural fluid albumin gradient >1.2 g/dL suggests heart failure as the cause even when exudative criteria are met 6
  • Elevated pleural fluid NT-proBNP levels strongly support cardiac origin 5

Diagnostic Approach to Confirm Heart Failure as the Cause

• Echocardiography is essential to identify:
  • Systolic or diastolic dysfunction
  • Severe valvular abnormalities
  • Elevated central venous pressure (via IVC assessment) 1, 4
• Thoracic ultrasound findings supporting heart failure include:
  • Interstitial syndrome
  • Simple (non-complex) pleural effusion
  • Compression atelectasis 4
• Serum NT-proBNP ≥1500 μg·mL⁻¹ strongly supports heart failure as the cause 4, 1

Management of Heart Failure-Related Pleural Effusions

• First-line treatment is optimization of heart failure therapy:
  • Diuretics (particularly loop diuretics)
  • ACE inhibitors
  • Beta-blockers
  • Other heart failure medications 1, 5
• For large, symptomatic effusions despite optimal medical therapy:
  • Therapeutic thoracentesis may be required 1, 5
• For recurrent effusions requiring frequent drainage:
  • Consider tunneled pleural catheter (IPC) or talc pleurodesis 1, 7
  • Note: Long-term indwelling catheters carry risk of complications including empyema 7

Important Clinical Considerations

• The presence of pleural effusion at hospital discharge is associated with increased risk of rehospitalization and mortality within the following year 6
• Unnecessary drainage should be avoided as pleural effusions typically don't cause significant hypoxemia except in specific cases 4, 1
• When evaluating unilateral effusions in heart failure patients, consider alternative diagnoses if:
  • Weight loss, chest pain, or fevers are present
  • Elevated white cell count or C-reactive protein
  • CT evidence of malignancy or infection 4
• Medium to large effusions are associated with significantly higher filling pressures than small effusions 2

Differential Diagnosis

• Malignant pleural effusion (particularly lung and breast cancer) 4
• Parapneumonic effusion/pleural infection 4
• Pulmonary embolism 4
• End-stage renal failure (may cause effusions through multiple mechanisms) 4
• Drug-induced pleural effusions (methotrexate, procarbazine, cyclophosphamide, bleomycin) 4