The Diagnostic Approach to Pericardial Effusions

PE = Pericardial Effusion
LV = Left Ventricle
RV = Right Ventricle

Pericardial effusions may present asymptomatically, as part of a systemic illness, or with symptoms of pericarditis. Examination findings are variable, but the presence of a pericardial friction rub is suggestive. Clinical features of tamponade must be assessed (such as dyspnoea/tachypnoea/hypotension/shock/tachycardia/raised JVP/Kussmaul’s sign/absent y descent/Pulsus paradoxus), as their presence indicates the need for urgent therapeutic pericardiocentesis. ECG findings such as low voltage, electrical alternans or pericarditis (PR depression, generalised  ST elevation, T wave inversion) are again suggestive, but do not alter management. CXR may be normal until the effusion is large, but may reveal  a globular cardiac silhouette or epicardial halo sign (lucent lines within the pericardial shadow).

Transthoracic Echo is the Gold standard for detection, showing an echolucent space between parietal pericardium and myocardium. Most sensitive views are the apical 4-chamber: near the right atrium, Parasternal short axis: behind LV, and subcostal.

The aetiology is vast, but 60% are secondary to a known premorbid condition; 20-30% are idiopathic, 25% infective, 20% malignant, ~10% metabolic, 5-10% collagen vascular. If inflammation is present (eg pericardial pain, rub, fever, diffuse ST changes), then up to 80% of cases will be idiopathic or infective. Tamponade without inflammation suggests consideration of neoplastic processes. If no cause is evident, it may be useful to undertake medication review, testing for TB and other infections (although viral serology is of limited utility), autoimmune screens (eg. anti-dsDNA, complement), and in some cases CT thorax.

Pericardiocentesis should be performed in tamponade, along with fluid resuscitation, if required. In all other circumstances, careful consideration of the risk/benefit ratio is required. Diagnostic yield is as low as 6%. It should not be performed in aortic dissection, coagulopathy, thrombocytopaenia, or with a small, posterior or loculated effusion.
The management of effusion without tamponade should be based upon the underlying aetiology. In addition, if inflammation is present, anti-inflammatories can provide symptomatic relief, as well as reducing effusion size. Consider surgical pericardiectomy for recurrent or chronic effusions.

Key Points

• Echocardiogram is the gold standard for detection of effusion
• Effusion ≠ need for pericardiocentesis
• Tamponade is treated with fluid resucitation and pericardiocentesis
• Pericardiocentesis is not always safe/feasible
• Non-emergent pericardiocentesis should not be attempted without adjuvant imaging (echo better than fluoroscopy)
• Up to 1/3 of effusions will be idiopathic