Pericardial effusion overview

# Overview
There is limited information about the historical perspective of pericardial effusion. However, percutaneous pericardiocentesis was first described in 1840 by Frank Schuh. By the 20th century, pericardiocentesis became the established technique for diagnosing and treating pericardial effusion. Before echocardiography, surgeons used a blind-subxiphoid approach; however, this was associated with serious organ injuries. However, the introduction of echo-guided pericardiocentesis improved the accuracy and safety of the procedure. The technique has been further refined over the past four decades.Pericardial effusion can be classified according to the nature of pericardial fluid into transudative, exudative, hemorrhagic, and malignant. Further, it can be classified according to the underlying cause into idiopathic, infectious, neoplastic, and post-operative. In addition, Horowitz et al. developed a classification for pericardial effusions based on echocardiographic findings (the degree of separation between the pericardium and epicardium). Pericardial effusion usually results from a disturbed equilibrium between the production and reabsorption of pericardial fluid.  This can occur in  infections and inflammations where there is increased production of pericardial fluid, increased microvascular pressure as in cardiac failure and renal failure cause, decreased plasma oncotic pressure as in cirrhosis and nephrotic syndrome, or in malignancy and hypothyroidism where there is inadequate drainage of the fluid. Pericardial effusion can be classified into serous, bloody and chylous effusions based on the composition of the effusion fluid. Infections and inflammation usually cause serous effusion while bloody effusions are as a result of trauma to the heart. Though iatrogenic causes and infections are the common etiologies, pericardial disease may also be a feature of other disorders such as inflammatory bowel disease. Aortic dissection or free wall rupture should also be considered in patients with unstable hemodynamics and pericardial tamponade.Most pericardial effusions are caused by inflammation of the pericardium, a condition called pericarditis. As the pericardium becomes inflamed, extra fluid is produced, leading to a pericardial effusion. Viral infections are one of the main causes of pericarditis and pericardial effusions. Infections causing pericardial effusions include cytomegalovirus, coxsackie virus, echovirus, and HIV. However, other conditions like injury to the pericardium or heart from a medical procedure, myocardial infarction, uremia, autoimmune disease and cancer should be considered in differential diagnosis of pericardial effusion.The underlying cause of pericardial effusion depend on the region where the patient is living. While malignancy is the most common cause of pericardial effusion in developed countries, infections such as tuberculosis and HIV seems to be the main etiologies of pericardial effusion in developing countries. Few studies have highlighted the following as possible risk factors for pericardial effusion (in the presence of a cause): older age, hypertension, diabetes mellitus, coronary artery disease, and atrial fibrillation. Patients with uncomplicated pericarditis usually have a self-resolving course within 2 weeks and can be managed on an outpatient basis. However Cardiac tamponade, purulent pericardial effusion, immunocompromised state, history of cancer, dialysis, use of oral anti-coagulation require urgent intervention. The prognosis of pericardial effusion depends on the underlying etiology being especially poor in patients with neoplastic pericardial effusion and very good in idiopathic/viral pericarditis. Pericardial effusion is a relatively common finding and sometimes the clinical picture of the patient leads directly to the cause for pericardial effusion. Mild pericardial effusion is a relatively a common finding, especially in elderly women and they are usually asymptomatic. Common symptoms may include fever, fatigue, muscle aches, shortness of breath, nausea, vomiting, and diarrhea. Large, serious pericardial effusions, or smaller ones that develop quickly, may cause other symptoms that include shortness of breath, palpitations (sensation that the heart is pounding or beating fast), light-headedness , and cool, clammy skin. The vital signs of a patient with small pericardial effusion are often normal. Fever suggests an underlying infectious or inflammatory cause, and the presence of a purulent effusion must be ruled out. The common signs include tachycardia, pulsus paradoxus, hypotension in cardiac tamponade, jugular venous distension, prominent Y descent, Kussmaul's sign, pleural dullness, decreased breath sounds, distant heart sounds, hepatomegaly, ascites in chronic cases, and ankle edema in chronic cases. Laboratory investigations for pericardial effusion include the leukocyte count, C-reactive protein, and ESR for ruling out inflammatory causes. The cardiac troponin is elevated if there is an injury to the underlying myocardium, a condition termed as myopericarditis. Diagnostic pericardiocentesis and biopsy help in identifying an underlying infectious or malignant process. The EKG in patients with pericardial effusion may demonstrate low voltages (micro-voltages or short QRS complexes) and electrical alternans.Chest X ray is normal in cases of mild-moderate pericardial effusion. Cardiomegaly is seen when pericardial effusion > 250 ml. However it can be used to rule out other causes of chest pain. The American College of Cardiology (ACC), the American Heart Association (AHA), and the American Society of Echocardiography in their recommendations on echocardiography gave strong recommendations for echocardiography in pericardial disease. The finding usually include presence of moderate and large pericardial effusion, swinging of the heart within the effusion and reversal of right atrial and right ventricular diastolic transmural pressures. Echocardiography should be performed if there is a suspicion of tamponade (e.g. distended neck veins, pulsus paradoxus). Computed tomography is an effective diagnostic tool in cases of pericardial effusion as it helps us to narrow down on the etiology by determining the amount and nature of the pericardial fluid. CT is useful especially in identifying hemorrhagic effusions or clots within the pericardium. A pericardial effusion is often incidentally noted on CT scans obtained for other indications. The mainstay of treatment for pericardial effusion is pericardial fluid drainage. Indications for pericardiocentesis or a pericardial window include cardiac tamponade, for diagnostic purposes if there is suspected purulent, tuberculosis, or neoplastic pericarditis, and the presence of a large, persistent, symptomatic pericardial effusion.

# Historical Perspective
There is limited information about the historical perspective of pericardial effusion. However, percutaneous pericardiocentesis was first described in 1840 by Frank Schuh. By the 20th century, pericardiocentesis became the established technique for diagnosing and treating pericardial effusion. Before echocardiography, surgeons used a blind-subxiphoid approach; however, this was associated with serious organ injuries. However, the introduction of echo-guided pericardiocentesis improved the accuracy and safety of the procedure. The technique has been further refined over the past four decades.

# Classification
Pericardial effusion can be classified according to the nature of pericardial fluid into transudative, exudative, hemorrhagic, and malignant. Further, it can be classified according to the underlying cause into idiopathic, infectious, neoplastic, and post-operative. In addition, Horowitz et al. developed a classification for pericardial effusions based on echocardiographic findings (the degree of separation between the pericardium and epicardium).

# Pathophysiology
Pericardial effusion usually results from a disturbed equilibrium between the production and reabsorption of pericardial fluid.  This can occur in  infections and inflammations where there is increased production of pericardial fluid, increased microvascular pressure as in cardiac failure and renal failure cause, decreased plasma oncotic pressure as in cirrhosis and nephrotic syndrome, or in malignancy and hypothyroidism where there is inadequate drainage of the fluid.

# Causes
Pericardial effusion can be classified into serous, bloody and chylous effusions based on the composition of the effusion fluid. Infections and inflammation usually cause serous effusion while bloody effusions are as a result of trauma to the heart. Though iatrogenic causes and infections are the common etiologies, pericardial disease may also be a feature of other disorders such as inflammatory bowel disease. Aortic dissection or free wall rupture should also be considered in patients with unstable hemodynamics and pericardial tamponade.

# Differentiating Pericardial Effusion from Other Diseases
Most pericardial effusions are caused by inflammation of the pericardium, a condition called pericarditis. As the pericardium becomes inflamed, extra fluid is produced, leading to a pericardial effusion. Viral infections are one of the main causes of pericarditis and pericardial effusions. Infections causing pericardial effusions include cytomegalovirus, coxsackie virus, echovirus, and HIV. However, other conditions like injury to the pericardium or heart from a medical procedure, myocardial infarction, uremia, autoimmune disease and cancer should be considered in differential diagnosis of pericardial effusion.

# Epidemiology and Demographics
The underlying cause of pericardial effusion depend on the region where the patient is living. While malignancy is the most common cause of pericardial effusion in developed countries, infections such as tuberculosis and HIV seems to be the main etiologies of pericardial effusion in developing countries.

# Risk Factors
Few studies have highlighted the following as possible risk factors for pericardial effusion (in the presence of a cause): older age, hypertension, diabetes mellitus, coronary artery disease, and atrial fibrillation.

# Screening
There is insufficient evidence to recommend routine screening for pericardial effusion.

# Natural History, Complications, and Prognosis
Patients with uncomplicated pericarditis usually have a self-resolving course within 2 weeks and can be managed on an outpatient basis. However Cardiac tamponade, purulent pericardial effusion, immunocompromised state, history of cancer, dialysis, use of oral anti-coagulation require urgent intervention. The prognosis of pericardial effusion depends on the underlying etiology being especially poor in patients with neoplastic pericardial effusion and very good in idiopathic/viral pericarditis.;

# Diagnosis

## Diagnostic Study of Choice
Pericardial effusion is primarily diagnosed based on the clinical evaluation along with electrocardiographic and chest radiograph findings, which may suggest the presence of a pericardial effusion. Echocardiography must be performed in all patients with possible pericardial effusion. Echocardiography is an excellent method for detection and estimation of the size of pericardial effusions.

## History and Symptoms
Pericardial effusion is a relatively common finding and sometimes the clinical picture of the patient leads directly to the cause for pericardial effusion. Mild pericardial effusion is a relatively a common finding, especially in elderly women and they are usually asymptomatic. Common symptoms may include fever, fatigue, muscle aches, shortness of breath, nausea, vomiting, and diarrhea. Large, serious pericardial effusions, or smaller ones that develop quickly, may cause other symptoms that include shortness of breath, palpitations (sensation that the heart is pounding or beating fast), light-headedness , and cool, clammy skin.

## Physical Examination
The vital signs of a patient with small pericardial effusion are often normal. Fever suggests an underlying infectious or inflammatory cause, and the presence of a purulent effusion must be ruled out. The common signs include tachycardia, pulsus paradoxus, hypotension in cardiac tamponade, jugular venous distension, prominent Y descent, Kussmaul's sign, pleural dullness, decreased breath sounds, distant heart sounds, hepatomegaly, ascites in chronic cases, and ankle edema in chronic cases

## Laboratory Findings
Laboratory investigations for pericardial effusion include the leukocyte count, C-reactive protein, and ESR for ruling out inflammatory causes. The cardiac troponin is elevated if there is an injury to the underlying myocardium, a condition termed as myopericarditis. Diagnostic pericardiocentesis and biopsy help in identifying an underlying infectious or malignant process.

## Electrocardiogram
The EKG in patients with pericardial effusion may demonstrate low voltages (micro-voltages or short QRS complexes) and electrical alternans.

## X-ray
Chest X ray is normal in cases of mild-moderate pericardial effusion. Cardiomegaly is seen when pericardial effusion > 250 ml. However it can be used to rule out other causes of chest pain.

## Echocardiography and Ultrasound
The American College of Cardiology (ACC), the American Heart Association (AHA), and the American Society of Echocardiography in their recommendations on echocardiography gave strong recommendations for echocardiography in pericardial disease. The finding usually include presence of moderate and large pericardial effusion, swinging of the heart within the effusion and reversal of right atrial and right ventricular diastolic transmural pressures. Echocardiography should be performed if there is a suspicion of tamponade (e.g. distended neck veins, pulsus paradoxus).

## CT scan
Computed tomography is an effective diagnostic tool in cases of pericardial effusion as it helps us to narrow down on the etiology by determining the amount and nature of the pericardial fluid. CT is useful especially in identifying hemorrhagic effusions or clots within the pericardium. A pericardial effusion is often incidentally noted on CT scans obtained for other indications.

## MRI
MRI allow assessment of the entire chest and detection of associated abnormalities in the mediastinum, lungs and adjacent structures. MRI also delineate more precisely the spacial distribution of pericardial effusion in complex pericardial collections. It may be very useful in the investigation of the presence and extension of neoplastic disease.

# Treatment

## Medical Therapy
Treatment of pericardial effusion depends on the underlying cause and the severity of the problem. Some pericardial effusions remain small and never require treatment. Patients with acute inflammatory signs may get symptomatic relief with anti-inflammatory drugs. If the effusion is compromising heart function and causing cardiac tamponade, it will need to be drained, most commonly by a needle inserted through the chest wall and into the pericardial space.

## Interventions
The mainstay of treatment for pericardial effusion is pericardial fluid drainage. Indications for pericardiocentesis or a pericardial window include cardiac tamponade, for diagnostic purposes if there is suspected purulent, tuberculosis, or neoplastic pericarditis, and the presence of a large, persistent, symptomatic pericardial effusion.

## Primary Prevention

## Secondary Prevention