What causes fluid around the heart

Overview

Fluid around the heart, medically termed pericardial effusion, is a condition where excess fluid accumulates in the pericardial sac. The pericardium is a double-layered membrane that surrounds the heart, providing lubrication and protection. Normally, there is a small amount of fluid (about 15-50 ml) between these layers to allow the heart to beat smoothly. However, when this space fills with an abnormal amount of fluid, it can impede the heart's ability to function effectively.

What is Pericardial Effusion?

Pericardial effusion is characterized by the abnormal collection of fluid within the pericardial cavity. This fluid can be serous fluid (similar to plasma), blood (hemopericardium), pus (purulent pericarditis), or chylous fluid (lymphatic fluid). The amount of fluid can range from small to very large, and the rate at which it accumulates is crucial in determining its impact on heart function. A slow accumulation of a large amount of fluid may be tolerated better than a rapid accumulation of a smaller amount.

Common Causes of Fluid Around the Heart

The causes of pericardial effusion are diverse and can be broadly categorized:

Inflammation of the Pericardium (Pericarditis)

This is a leading cause. Pericarditis itself can be triggered by several factors:

• Infections: Viral infections are the most common cause of acute pericarditis. Bacteria, fungi, and tuberculosis can also cause it, though less frequently.
• Autoimmune Diseases: Conditions where the body's immune system mistakenly attacks its own tissues can inflame the pericardium. Examples include lupus (systemic lupus erythematosus), rheumatoid arthritis, and scleroderma.
• Post-Myocardial Infarction (Heart Attack): Following a heart attack, inflammation can occur in the damaged heart tissue and spread to the pericardium. The Dressler's syndrome, a form of post-cardiac injury syndrome, is characterized by pericarditis and effusion occurring weeks to months after a heart attack.
• Uremia: In people with advanced kidney failure, the buildup of waste products in the blood (uremia) can cause inflammation of the pericardium.
• Radiation Therapy: Radiation treatment to the chest, often for lung cancer or breast cancer, can damage the pericardium and lead to effusion.
• Trauma: Blunt or penetrating chest trauma can directly injure the pericardium and heart, leading to bleeding into the pericardial sac (hemopericardium).
• Medications: Certain drugs, such as procainamide, hydralazine, and isoniazid, have been linked to drug-induced lupus and subsequent pericarditis.

Cancer

Cancer can affect the pericardium in several ways:

• Metastasis: Cancer that spreads (metastasizes) from other parts of the body to the pericardium is a common cause of malignant pericardial effusion. Lung cancer, breast cancer, lymphoma, and leukemia are frequently implicated.
• Primary Pericardial Tumors: Though rare, tumors can originate in the pericardium itself.

Heart Conditions

Problems with the heart itself can lead to fluid buildup:

• Heart Failure: Congestive heart failure can cause fluid to back up in the body, including the pericardial space.
• Aortic Dissection: A tear in the aorta, the major artery carrying blood from the heart, can rupture into the pericardial sac, causing a life-threatening hemopericardium.
• Myxedema: Severe hypothyroidism can sometimes be associated with pericardial effusion.

Other Causes

Less common causes include:

• Allergic reactions
• Certain medical procedures
• Idiopathic pericarditis (cause unknown)

Symptoms of Pericardial Effusion

The symptoms depend on the amount of fluid and how quickly it accumulates. Small effusions may cause no symptoms. Larger or rapidly accumulating effusions can lead to:

• Chest pain (often sharp and stabbing, worse when lying down or breathing deeply)
• Shortness of breath
• Cough
• Fever
• Fatigue
• Palpitations
• Swelling in the legs or abdomen

Complications: Cardiac Tamponade

The most serious complication of pericardial effusion is cardiac tamponade. This occurs when the accumulated fluid puts excessive pressure on the heart, preventing its chambers from filling properly with blood. This significantly reduces the heart's ability to pump blood to the rest of the body. Symptoms of cardiac tamponade include severe shortness of breath, rapid heart rate, low blood pressure, dizziness, and fainting. Cardiac tamponade is a medical emergency requiring immediate treatment, usually by draining the excess fluid.

Diagnosis and Treatment

Diagnosis often involves physical examination (listening for muffled heart sounds), electrocardiogram (ECG), chest X-ray, and echocardiogram (ultrasound of the heart), which is the most definitive test for detecting and quantifying pericardial effusion. Blood tests and sometimes a CT or MRI scan may be used to identify the underlying cause. Treatment focuses on addressing the cause of the effusion and, if necessary, removing the excess fluid through pericardiocentesis (a procedure to drain the fluid with a needle) or surgery. Anti-inflammatory medications are often used to treat the underlying pericarditis.