11. Pericardial Effusion and Cardiac Tamponade

Definitions

  • Pericardial effusion = fluid in the pericardial space.
  • Cardiac tamponade = when pericardial effusion leads to increased pressure, impairing ventricular filling and resulting in decreased cardiac output. This is a clinical diagnosis although echo findings can be quite suggestive showing right sided collapse, aplethoric IVC and changes in flow across valves with respiration).

Etiologies/Risk Factors

  • Causes of pericardial effusion: malignancy, pericarditis, myocarditis, heart failure, aortic dissection, post MI or cardiac surgery, trauma, uremia, autoimmune, myxedema, infection (TB, HIV), and often idiopathic.
  • Development of cardiac tamponade is more correlated with how quickly fluid accumulates, rather than the absolute size of the pericardial effusion.

Evaluation/Differential Diagnosis

1. Symptoms: dyspnea, chest pain, nausea, abdominal pain.

2. Signs of tamponade:​

  • Beck’s triad (elevated JVP, hypotension, quiet heart sounds). Caveat: described in surgical patients and insensitive in medical patients.
  • Most patients are tachycardic. Low blood pressure may be a late finding in many.
  • Always check and follow a pulsus paradoxus: this is a critical physical exam finding and will help dictate whether urgent pericardiocentesis is needed. Positive likelihood ratio 3.3, sensitivity ~82%.
    • Pulsus paradoxus: drop in SBP >10 mmHg during a normal inspiration. Normally, inspiration causes increased filling of right heart which slightly bows the interventricular septum to the left, decreasing filling of the left heart and leading to decreased stroke volume and blood pressure. In tamponade, this normal physiology is exaggerated.
    • Using manual BP cuff (patient should be breathing normally – don’t ask them to take deep breaths):
      • Slowly inflate the manual BP cuff to just above the patient’s systolic BP.
      • Slowly (by 1-2 mmHg at a time) deflate the cuff and record the BP when you first hear Korotkoff sounds intermittently (it will vary with respiration, and should be heard only with expiration).
      • Keep deflating the cuff and eventually you will hear Korotkoff sounds with both inspiration and expiration. Record this systolic BP.
      • Pulsus paradoxus is the difference between the two recorded systolic BPs and should be less than 10 mm Hg.
    • If >10 mm Hg, this may indicate cardiac tamponade because when the RV fills, the septum shifts leftward and LV filling is reduced, thereby reducing LV stroke volume.
    • Using arterial line: if a patient has an arterial line in place, measure the difference in systolic arterial pressure between inspiration and expiration to determine the pulsus paradoxus.
    • Differential diagnosis for positive pulsus paradoxus: severe asthma, COPD, hypovolemic shock, and pulmonary embolism.

3. ECG: low voltage; electrical alternans (alternating short/tall QRS complexes seen as the heart swings) can be seen in large pericardial effusion and does not necessarily imply cardiac tamponade. If pericarditis, can see diffuse ST elevation and PR depression.

4. CXR: may show large, globular heart.

5. With a PA catheter, elevation and equalization of diastolic intracardiac pressures is seen. This is due to uniform increase in pericardial pressure which affects all chambers of the heart, causing limitation of ventricular filling and leading to reduction in cardiac output.

Management

  • If you suspect tamponade, obtain a STAT bedside echo and prepare for possible pericardiocentesis.
  • Echo findings: pericardial effusion; increased respiratory variation in mitral and tricuspid inflow; diastolic collapse of the right atrium and right ventricle; dilated inferior vena cava.
  • Remember that anything that causes extrinsic compression of the heart can simulate cardiac tamponade (e.g., abdominal compartment syndrome, tension pneumothorax).
  • Treatment of tamponade:
    • Pericardiocentesis, possibly with indwelling drain if reaccumulation is expected.
    • Fluids (goal CVP ~15 mmHg) as tamponade is a preload-dependent state although do not give excessive amounts as this will increase pericardial pressure.
    • Vasopressors to support BP (dopamine).
    • Pericardial effusions without tamponade can usually be managed conservatively. Consider pericardiocentesis for purulent effusions or if suspicion of infection/malignancy exists; diagnostic yield is quite low, however.
    • If tapped, send fluid for: glucose, protein, LDH, cell-count/differential, gram stain/culture, AFB, cytology. Can send ADA levels if suspect TB. Bloody fluid usually suggests TB or tumor though also seen in rheumatic fever, trauma, and uremic pericarditis.
    • Pericardial window by CT surgery should be entertained (hole cut in pericardial sac to allow pericardial fluid to be drained into the pleural space) in cases where fluid is expected to continue to accumulate despite initial removal (e.g. malignancy where treatment is unlikely to quickly decrease pericardial fluid accumulation).

 

Little WC, Freeman GL. Pericardial Disease. Circulation. 2006 113: 1622-1632. 

Roy CL, Minor MA, Brookhart MA, et al. Does this patient with a pericardial effusion have cardiac tamponade? JAMA 2007;297:1810-1818.

Spodick DH. Acute cardiac tamponade. N Engl J Med 2003;349:684-690.