Pericardial Effusion

The term pericardial effusion describes a collection of fluid in the pericardial space. The amount of fluid may range in volume from a few millilitres up to 2 litres. It may be a transudate (hydropericardium), exudate (pyopericardium), or haemopericardium. Large effusions are common with neoplastic, tuberculous, uraemic pericarditis, myxoedema, and parasitic infections. Loculated effusions are more common when scarring is present e.g. post-surgery, post-trauma, post-purulent pericarditis. Massive chronic pericardial effusions are rare and make up only 2 to 3.5% of all large effusions.

Pericardial effusion has been found in 3.4% of subjects at post-mortem.¹
A higher incidence is associated with certain diseases:

• 21% of cancer patients have metastases to the pericardium; most commonly lung, breast and leukaemia.¹
• 41-87% of HIV patients, with or without AIDS, are found to have asymptomatic effusion.^2,3

The symptoms produced by a pericardial effusion depend on the speed with which the effusion is formed, as well as the size of the effusion. Many small to moderate effusions formed over a long period of time will be relatively asymptomatic. However even small effusions which have occurred rapidly may compromise the circulation and cause tamponade.

• Weak peripheral pulses. Heart sounds are distant.
• Where there is local compression, dyspnoea, dysphagia, hoarseness (recurrent laryngeal nerve), hiccups (phrenic nerve), or nausea can occur.
• Pulsus paradoxus - an exaggeration of the variation in pulse volume on breathing
• Widened pulse pressure
• Tachycardia ± pericardial rub
• Tachypnoea ±Ewart's sign - bronchial breathing at angle of left scapula, caused by compression of the lung
• ± Hepatosplenamegaly (if pericardial effusion is long-standing)
• ± Oedema
• In tamponade, chest discomfort, tachypnoea, and dyspnoea on exertion may progress to orthopnoea, cough, and dysphagia. There may occasionally also be episodes of unconsciousness.
• Insidiously developing tamponade may present with the signs of its complications e.g. renal failure and mesenteric ischaemia.
• The heart may move within the pericardial cavity ("swinging heart")where there is a large pericardial effusion. This unusual motion of the heart creates "pseudo" conditions like pseudomitral valve prolapse, pseudosystolic anterior motion of the mitral valve, paradoxical motion of the interventricular septum, and midsystolic aortic valve closure.⁴

There are many causes of a pericardial effusion which may be either local, as in acute or chronic pericarditis, or systemic.
Amongst the causes of pericardial effusion are:

Differential diagnosis will include the causes of right and left heart failure including:

• Cardiac tamponade
• Pulmonary embolus
• Constrictive pericarditis
• Ventricular aneurysm
• Myocardial infarction
• Cardiomyopathy.

• FBC; is white cell count raised, or cytopenia as sign of underlying disease e.g. cancer or HIV?
• U&E's; is uraemia present?
• TSH
• Cardiac enzymes; troponin level is often minimally elevated in acute pericarditis.
• Auto-antibodies e.g. Rheumatoid factor, Anti-nuclear antibody
• Echocardiogram. Transesophageal echocardiography is particularly useful in post-operative loculated pericardial effusion, or in identifying metastases and pericardial thickening.
• CXR may show increased cardio-thoracic ratio. Large effusions are depicted as globular cardiomegaly with sharp margins. On well-penetrated lateral films, pericardial fluid is suggested by lucent lines within the cardiopericardial shadow.
• ECG may show raised ST segments with MI or pericarditis. There may also be diminished QRS and T-wave voltages, PR-segment depression, ST-T changes, bundle branch block, and electrical alternans.
• Pericardial fluid aspiration for analysis e.g. protein level, cell count, culture. Smear for acid-fast bacilli in suspected tuberculosis infection, especially in patients with HIV.
• ± MRI/CT scan. MRI can detect as little as 30 mL of pericardial fluid
  Both MRI and CT scan may be superior to echocardiography in detecting loculated pericardial effusions and pericardial thickening.

Non-Drug

Oxygen therapy will help to relieve symptoms in patients whose circulation is compromised by a pericardial effusion.

Drugs

• Treatment of the underlying condition e.g. with cytotoxic agents for malignancy, or steroids and non-steroidal agents for rheumatoid arthritis, will help to reduce the volume of fluid in the pericardial sac.
• Patients with dehydration and hypovolaemia may temporarily improve with intravenous fluids improving ventricular filling.

Surgical

• Pericardiocentesis may be used to reduce the volume of fluid in the pericardial sac.⁴It may not be necessary when the diagnosis can be made based on other systemic features, or the effusions are very small or resolving under anti-inflammatory treatment. Pericardiocentesis is conyta-indicated in wounds, ruptured ventricular aneurysm, or dissecting aortic haematoma. Needle evacuation is impossible and surgical drainage is mandatory.
• A surgical approach is recommended only in patients with very large chronic effusion, for whom repeated pericardiocenteses have been unsuccessful.
• Subxiphoid pericardial window creation with pericardiostomy, is used as an alternative to pericardiocentesis in some centres. This procedure is associated with low morbidity, mortality, and recurrence rates and it can be performed under local anesthesia. However, it may be less effective when effusion is loculated.
  A recent study suggests that this may be safer and more effective at reducing recurrence rates than pericardiocentesis.⁵
• In patients with persistent effusions, a pleuropericardial window may be created, either by means of video assisted thoracic surgery (VATS) or a thoracotomy.The pleuropericardial window will allow for drainage of the fluid into the pleura from where it is more easily reabsorbed. It allows resection of a wider area of pericardium than the subxiphoid approach. It also allows the surgeon to deal with any concomitant pleural pathology. However it does require general anaesthesia with single lung ventilation.
• If the effusion recurs balloon pericardotomy may also be considered. A catheter is placed in the pericardial space under fluoroscopy, which, after inflation of the balloon, creates a channel for passage of fluid into the pleural space, where reabsorption occurs more readily. This may be useful for recurrent effusions.
• An alternative is pericardial sclerosis. Several sclerosing agents have been used with differing success rates e.g. tetracycline, doxycycline, cisplatin and 5-fluorouracil. The catheter may be left in place for repeat instillation, if necessary, until the effusion resolves.Complications include severe pain, fever, infection and atrial dysrhythmias. Success rates are reported as >90% at 30 days.^6,7
• Resistant neoplastic processes may require intrapericardial treatment.

• Pericardial tamponade; this can lead to severe haemodynamic compromise and death.
• Chronic pericardial effusion; these are effusions lasting longer than 6 months and they are usually well tolerated.

The prognosis for a patient with a pericardial effusion will depend on the underlying cause; large effusions generally indicate more serious disease.
If the precipitating cause is not life-threatening, small, chronic effusions are usually well tolerated.