Continuing Education Activity

A pericardial effusion refers to the accumulation of excess fluid in the pericardial sac surrounding the heart. In a healthy individual, the pericardial sac contains between 15 and 50 milliliters (mL) of serous fluid. This fluid may be transudative, exudative, or sanguineous and may contain infectious organisms or malignant cells. It may be due to infection, inflammation, or direct filling of the pericardial sac by blood from a defect in the myocardium (iatrogenic or traumatic injury or cardiac wall rupture) or backfilling from an ascending aortic dissection that dissects into the pericardium. This activity examines when this condition should be considered on a differential diagnosis and how to properly evaluate for it and highlights the role of the interprofessional team in caring for patients with this condition.

Objectives:

• Describe the presentation of pericardial effusion.
• Outline the testing that should be done in patients who present with pericardial effusions.
• Explain management considerations for pericardial effusions.
• Summarize interprofessional team strategies for improving care coordination and communication to enhance outcomes for patients affected by pericardial effusions.

Introduction

A pericardial effusion refers to the accumulation of fluid in the pericardial sac surrounding the heart. The pericardial sac is composed of the thin visceral pericardium which consists of a single layer of cells adherent to the cardiac epicardium and the thicker, fibrous parietal pericardium composed of collagen and elastin which is adherent to the lungs, diaphragm, sternum, great vessels, and other mediastinal structures surrounding the heart. In a healthy individual, the pericardial sac contains between 15 mL and 50 mL of serous fluid.[1][2][3]

Etiology

The etiology of a pericardial effusion varies widely and can be divided into several categories:

• Infectious: Pericardial effusion may be due to infection with a multitude of viral, bacterial, fungal, and even parasitic pathogens. 
• Inflammatory/rheumatologic: Numerous auto-immune disorders, including systemic lupus erythematosus, rheumatoid arthritis, and Sjogren syndrome, can cause a pericardial effusion.
• Neoplastic: Both metastatic disease and primary cardiac tumors can cause pericardial effusions. Lung cancer is the most common cause of malignant pericardial effusion.
• Trauma: Blunt, penetrating, and iatrogenic injury to the myocardium, aorta, or coronary vessels can lead to the accumulation of blood within the pericardial sac.
• Cardiac: Post-myocardial infarction (referred to as Dressler syndrome), cardiac surgery, cardiac wall rupture.
• Vascular: Aortic dissection, type A, can be complicated by cardiac tamponade.
• Idiopathic: Many cases of pericardial effusion are idiopathic.
• Other: There are numerous additional etiologies of pericardial effusion, including radiation, chronic kidney disease, renal failure, congestive heart failure, cirrhosis, hypothyroidism leading to myxedema, ovarian hyperstimulation syndrome, and drug-induced.

Epidemiology

Pericardial effusion is possible across all ages and populations. The predominant etiology of the effusion varies by demographic characteristics such as age, geography, and comorbidities. There is little data regarding the prevalence and incidence of pericardial effusions. Viral pericarditis leading to effusion is the most common cause in the developed world. In developing areas, pericardial effusion due to Mycobacterium tuberculosis is quite prevalent. Bacterial and parasitic etiologies are less common. Among non-inflammatory pericardial effusions, multiple malignant neoplasms can lead to pericardial effusion. In patients with pericardial effusion, malignancy ranges between 12 and 23%. In patients with HIV, pericardial effusion was reported in 5 to 43%, depending on the inclusion criteria, with 13% having moderate to severe effusion. According to a study in pediatric patients, post-cardiac surgery (54%), neoplasia (13%), renal (13%), idiopathic or viral pericarditis (5%), and rheumatologic (5%) were the major underlying etiologies of pericarditis and pericardial effusions in children.[1][4][5][6]

Pathophysiology

Pericardial effusion is an acute or chronic accumulation of fluid within the pericardial space. Effusion can be transudative, exudative, or sanguineous. The pericardium has limited elasticity, and in acute settings, only 100 ml to 150 mL of fluid is necessary to cause cardiac tamponade.  The fluid accumulation increases pressure in the pericardial sac leading to the compression of the heart, especially the right heart, due to a thinner wall. Impaired diastolic filling of the right heart causes venous congestion. Reduction in the diastolic filling of the left ventricle results in decreased stroke volume. Tachycardia and increased contractility is the initial compensatory response mediated by adrenergic stimulation to maintain cardiac output.  However, eventually, blood pressure and cardiac output progressively decline. In chronic settings, the pericardial effusion may become one to two liters in size before it causes cardiac tamponade as long as the accumulation is gradual and the parietal pericardium has adequate time to stretch and accommodate the increased volume. [7][8][9]

History and Physical

The clinical presentation of pericardial effusion is along a spectrum from a clinically irrelevant, incidental finding to life-threatening cardiac tamponade. This wide variation is due in large part to the variable rate of accumulation of the pericardial fluid. Acute accumulation may cause impaired cardiac filling and decreased cardiac output with as little as 100 mL of fluid, while chronic and slow accumulation may lead to significant effusions of one to two liters that produce no significant hemodynamic effects. 

• History: In patients with pericardial effusion due to pericarditis, patients often present with chest pain and dyspnea, with symptoms that improve while sitting upright and worsen while lying flat due to the inflamed pericardium contacting adjacent structures. Patients may also present with symptoms that are not specific for pericardial effusion, including dyspnea, edema, and fatigue. Other essential elements of history include questions regarding recent illnesses, malignancy, history of tuberculosis and vaccination status, auto-immune disorders, history of chronic kidney disease or renal failure, or history of congestive heart failure, hypothyroidism, or liver disease.
• Physical exam: Pericardial effusion leading to pericardial tamponade should be on the differential for patients in cardiac arrest or with vital sign abnormalities, including hypotension and tachycardia. The classic teaching of Beck's triad (hypotension, jugular venous distension, and muffled heart sounds) is only found in a minority of patients. Other physical exam findings unique to pericardial effusion include Ewart's sign (dullness to percussion at the base of the left inferior scapular border in conjunction with tubular breath sounds and egophony). The physical exam of patients with a concern for cardiac tamponade should also include evaluation for pulsus paradoxus, which refers to a relative drop in systolic blood pressure by more than 10 mmHg during inspiration due to the collapse of the left ventricle at the expense of right ventricle. This leads to the bowing of the interventricular septum and augmented compression of the left side of the heart with decreased filling volumes and subsequent decreased stroke volume and systolic blood pressure.

While both history and physical exam are critical components of the evaluation for pericardial effusion and cardiac tamponade, the standard of care now includes additional modalities such as echocardiography to confirm the diagnosis.

Evaluation

Several tests can aid in evaluating a patient in whom pericardial effusion is the differential diagnosis.[10][11][12]

• Chest X-ray: The chest X-ray may can not directly identify pericardial effusion. If there is a significant, chronic effusion, then the heart may appear boot-shaped, and radiology may comment on a "water bottle sign" or a water bottle-shaped heart. There may also be evidence of pulmonary edema, engorgement of the pulmonary vessels, and/or pleural effusions on chest x-ray - none of which are sensitive or specific for pericardial effusion.
• ECG: The ECG findings vary from normal to non-specific ST-segment changes for small effusions. For large effusions or tamponade, the ECG may demonstrate electrical alternans, which is a specific but not sensitive finding. Electrical alternans refer to QRS complexes of varying heights corresponding to a back-and-forth motion of the heart within the pericardial sac as it swings on its anchored base during the cardiac cycle. If the pericardial effusion is due to pericarditis, then the ECG may show PR depressions or diffuse ST elevations.
• Echocardiography: Transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE) is the diagnostic modality of choice when evaluating for pericardial effusion. Echocardiography provides a dynamic assessment of the pericardial effusion allowing for quantification of the size of the effusion and determination of whether there is evidence of cardiac tamponade physiology. Pericardial effusion is identified as anechoic fluid surrounding the heart. In cases of hemopericardium with a clot, pyogenic effusions, or exudative effusions, there may be a hypoechoic clot or debris visible within the anechoic pericardial fluid. There are numerous criteria for the diagnosis of cardiac tamponade by TTE or TEE. Right atrial free-wall collapse or inversion during systole, right ventricular free wall collapse during diastole, increased septal bowing into the left ventricle during inspiration and the right ventricle during exhalation, a dilated inferior vena cava without respiratory variation in a spontaneously breathing patient in sinus rhythm, and increased flow across the mitral valve during exhalation and the tricuspid valve during inspiration are all potentially indicative of intrapericardial pressures that are greater than intracardiac pressures and potential pericardial tamponade. It is important to note that some of these echo findings are sensitive but not specific, while others are specific but not sensitive for cardiac tamponade.
• CT/MRI: Pericardial effusion can also be identified on CT or MRI of the chest or heart; however, this is not the diagnostic modality of choice.

Treatment / Management

Treatment for pericardial effusion ranges from watchful waiting for emergent intervention and depends largely on the suspected etiology. Small effusions without evidence of hemodynamic compromise are watched with serial echocardiography if deemed necessary or determined to be small enough that no follow-up is necessary. Large effusions may receive a diagnostic pericardiocentesis to evaluate the etiology or drained to provide symptomatic relief if the patient has associated symptoms such as dyspnea, chest discomfort, pulmonary or lower extremity edema, or decreased exercise tolerance. Effusions that have accumulated rapidly enough or have grown to such a size as to cause hemodynamic instability or collapse are managed emergently at the bedside, the cardiac catheterization lab, or the operating room. Techniques for drainage include needle pericardiocentesis via subxiphoid or anterior thoracic approach with or without placement of a pericardial drain for serial evacuation, percutaneous balloon pericardiotomy, emergent thoracotomy, and pericardiotomy, and surgical pericardial window via subxiphoid, anterior mini-thoracotomy, or video-assisted thoracoscopic surgery (VATS) approach. The type of intervention chosen is based on the etiology of the pericardial effusion, the clinical status of the patient at the time of the intervention, and the patient's expected clinical course.[13][14]

Of note, in patients who have large pericardial effusions with underlying ventricular dysfunction, there is a risk of the development of pericardial decompression syndrome (PDS) after pericardiocentesis. Pericardial decompression syndrome (PDS) is an infrequent, life-threatening complication following an uncomplicated pericardial evacuation for cardiac tamponade physiology.  PDS is characterized by paradoxical hemodynamic instability and/or pulmonary edema following otherwise non-complicated pericardial drainage. Physicians should be familiar with the prevention strategies for PDS and offer vulnerable patients very close clinical monitoring, especially those undergoing pericardial drainage for large malignant effusions for suspected tamponade.  A sensible strategy would not drain large quantities of pericardial fluid in a single sitting, especially in case of large pericardial effusions. The most reasonable approach would be to remove the amount of pericardial fluid just enough to result in the resolution of the cardiac tamponade physiology (which can be easily achieved by hemodynamic or echo-doppler monitoring) and then place prolonged pericardial drainage to achieve a slow and gradual removal of additional pericardial fluid. Prolonged pericardial drainage may be removed when there is a daily fluid return below 30-50 ml.[15]

Differential Diagnosis

• Acute pericarditis

• Cardiac tamponade

• Cardiogenic pulmonary edema

• Constrictive pericarditis

• Dilated cardiomyopathy

• Effusive-constrictive pericarditis

• Myocardial infarction

• Pulmonary embolism

Pearls and Other Issues

• Pericardial effusion is a relatively commonly encountered pathology.
• The etiology is widely varied.
• The effusion can range from incidental to life-threatening disease.
• The diagnostic modality of choice is an echocardiogram, although other modalities can provide critical information.
• Management is driven by the size of the effusion and the clinical status of the patient.
• Cardiothoracic surgeons are the consultant of choice for patients who are diagnosed with a pericardial effusion.

Enhancing Healthcare Team Outcomes

Pericardial effusions are common. Unlike chronic effusions, acute effusions in symptomatic patients need emergent treatment. The management of pericardial effusions is by an interprofessional team that includes a cardiologist, a radiologist, and a cardiac surgeon. While aspiration can help relieve symptoms and hemodynamic compromise in most patients, those occurring after a malignancy may require a pericardial window that can be done either open or via thoracoscopy. Symptomatic pericardial effusions that are not properly treated carry a very high mortality.