What Is Pericardial Effusion?

Most people have some knowledge of heart conditions such as heart failure and cardiac arrest, however, not many are aware of other heart conditions such as pericardial effusion. In this article, we aim to discuss pericardial effusion to enable you to have a clear understanding of this heart condition. 

Pericardial effusion is the collection of fluid within the covering sac of the heart, (known as the pericardial cavity).¹ The pericardium, which forms the pericardial cavity virtue of the space between its outer fibrous and inner serous layers, is a protective lining covering the heart and the blood vessels. It also holds the heart in position, providing cushioning effects against friction and swaying, in addition to providing a shield against infection.² 

Between the two layers of the pericardium is a space, which usually contains 20 to 40ml of a clear ultrafiltrate of the plasma.² Conditions which change the function or structure of the pericardium may result in the accumulation of fluid (in the form of blood, pus or others) within the cavity and this is termed pericardial effusion.

To know more about these causes, and how to identify, treat and prevent pericardial effusion, keep reading this article to harness this reliable information and more. 

Overview

The heart, due to its central role in the body, is covered and protected by a two-layered covering known as the pericardium. The space between these two layers normally contains a small amount of clear fluid to maintain smooth gliding and reduce friction and damage. However, things can go off-track and the space becomes filled with excessive fluid leading to abnormal contraction and relaxation of the heart, infection or even complete cessation of heart function. 

Pericardial effusion hinders the heart the ability to fully relax and accommodate enough volume of blood required to meet the body’s needs. In addition, the layers of the heart can become infected and accumulate fluid or pus which can potentially spread infection to the heart. 

Cardiac tamponade is an emergency condition in which, due to the accumulation of fluid within the pericardium, the heart is unable to deliver the required cardiac output, leading to heart failure and shock.³ Cardiac output is the total amount of blood pumped by the heart in one cardiac cycle that goes around the body supplying nutrients and oxygen while taking out waste products and carbon dioxide.⁴

When fluid accumulation in pericardial effusion occurs suddenly over a short period, a condition referred to as acute pericardial effusion, the volume capable of causing a tamponade is only about 100 - 150mls. However, in settings of a slowly accumulating fluid (chronic pericardial effusion), as much as 2 litres of fluid can gather before cardiac tamponade develops.¹

Pericardial effusion can present in various forms, from those without serious symptoms which are often identified incidentally to those with serious symptoms warranting emergency intervention to prevent death.¹ Symptoms such as pain, chest heaviness, difficulty in breathing, leg swelling and tiredness are usually reported by patients while your doctor may find signs such as raised jugular venous pressure, low blood pressure and muffled heart sounds. Features of the underlying cause such as malignancy, autoimmune disease and tuberculosis may be present in pericardial effusion. The main diagnosis is echocardiography which is essentially an ultrasound imaging of the heart and vessels in which the fluid accumulation can be seen and measured. 

Treatment is by treating the underlying cause. In emergencies such as cardiac tamponade, the fluid may have to be evacuated immediately using a needle aspiration technique called pericardiocentesis. 

Causes of pericardial effusion

There are many causes of pericardial effusion and generally, any condition that increases the volume of fluid in the pericardial space or decreases its recirculation can cause pericardial effusion. The causes of pericardial effusion can be categorized as follows:¹

1. Infections: Bacterial, viral, fungal and mycobacterial
2. Inflammatory conditions such as systemic lupus erythematosus
3. Malignancies, both those originating from the heart or pericardium and those resulting from secondary metastasis⁵
4. Cardiovascular causes such as aortic dissection, and Dressler’s syndrome (pericardial effusion occurring after myocardial infection). In aortic dissection, there is separation of the layers of the aorta, allowing blood to seep in-between and in the case of the proximal ascending type, result in pericardial effusion⁶
5. Trauma like blunt or penetrating chest trauma involving the myocardium
6. Iatrogenic such as following cardiac surgery, certain drugs or radiation therapy
7. Idiopathic pericardial effusion, where, in some cases, the cause is not found⁷

Signs and symptoms of pericardial effusion

When a person develops pericardial effusion, the following symptoms can be observed:¹

1. Pain around the chest, which may improve on sitting upright and worsen on lying flat
2. Difficulty in breathing due to lung congestion from the inability of the heart to recoil and receive blood from the lungs
3. Tiredness due to decreased cardiac output to deliver nutrients and oxygen to the body and remove waste products and carbon dioxide
4. Leg swelling involving both legs due to impaired venous return

On examining a person having pericardiac effusion, the following clinical signs can be identified:¹

1. Low blood pressure (hypotension) due to impaired function of the heart
2. Increased heart rate (tachycardia) as the heart compensates for poor output
3. Heart sounds may be distant or muffled on auscultation of the chest, due to the masking effect of the fluid
4. Jugular venous pressure is elevated. This is seen as engorged vessels on the neck due to incomplete relaxation of the heart to accommodate fluid returning through the veins
5. Pulsus paradoxus refers to an exaggerated decrease in systolic blood pressure of more than 10mmHg during inspiration⁸ 

Management and treatment for pericardial effusion

The management of pericardial effusion depends on the presentation. In mild cases, a ‘watchful waiting’ strategy is adopted while in serious cases, emergency interventions and in some cases surgery is advocated to yield desired outcome. Apart from the severity of the presentation, other factors considered in deciding the option of treatment include the cause of the effusion, the patient's clinical status (especially as it related to the cardiac function) and the suspected clinical course of the effusion. 

The various management options include:¹

1. Drainage through pericardiocentesis. This is a procedure where the needle is passed into the pericardial space to evacuate the excess fluid. The management team may decide to place a tube to maintain a continuous collection of the excess fluid
2. Percutaneous balloon pericardiotomy
3. Emergency thoracotomy or pericardiotomy - opening up to the chest to drain the effusion
4. Video-assisted thoracoscopic surgery approach

FAQs

How is pericardial effusion diagnosed?

The main diagnosis is echocardiography.^1,5 This is similar to an ultrasound that visualises the heart, large vessels and the pericardium. It can assess the volume (quantity) of fluid in the pericardium and give an idea of the type of fluid, like blood, clear fluid and pus. Other useful investigations include:¹

1. Chest X-ray where the shape of the heart, engorgement of pulmonary vessels or pleural effusion may trigger suspicion to conduct further tests to confirm or exclude pericardial effusion
2. Electrocardiography (ECG) may reveal ST-segment changes that may be a pointer to pericardial effusion
3. Computed Tomography (CT scan)
4. Magnetic Resonance Imaging (MRI)

How can I prevent pericardial effusion?

Preventive strategies include maintaining a healthy lifestyle preventing infections and cardiovascular protection against conditions such as myocardial infarction and aortic dissection. Regular hospital checks to diagnose early deviation of normal health and screening against malignancies are important. For those involved in vulnerable occupations and sports, blunt and penetrating chest injuries can be prevented or minimized by ensuring the proper use of personal protective equipment such as chest braces and cushions. 

Who are those at risk of pericardial effusion?

Those at risk of pericardial effusion include:

1. Those with autoimmune/inflammatory diseases such as SLE and Sjogren’s syndrome
2. Those with poor cardiovascular health such as myocardial infarction and aortic dissection
3. Those involved in sports or an occupation that predisposes them to chest injuries

When should I see a doctor?

Symptoms such as chest pain that usually worsens on lying down with associated tiredness and difficulty in breathing should require a medical evaluation to exclude pericardial effusion. Any chest pain and rapidly worsening dyspnoea following chest injuries either from road traffic or occupation accidents should seek immediate medical attention. 

Summary

Pericardial effusion occurs when fluid accumulates in the pericardial cavity surrounding the heart, affecting the heart's function. This may be caused by infections, malignancies, trauma, autoimmune conditions, surgeries, or cardiovascular conditions like aortic dissection or may just occur without any identifiable cause. 

To diagnose this condition, echocardiography is the gold standard investigation and treatment depends on the cause, severity and suspected clinical course. Treatment options include drainage using a needle (pericardiocentesis) or using surgical methods which may be open or thoracoscopic.

Protective wear for those prone to chest injuries, living a healthy lifestyle that protects from infections and cardiovascular complications and early presentation to evaluate suspicious symptoms are key preventive strategies.