What causes pericarditis

Overview

Pericarditis is the inflammation of the pericardium, the thin sac that surrounds your heart. This sac has two layers, with a small amount of fluid between them, allowing the heart to beat with minimal friction. When the pericardium becomes inflamed, the layers can rub against each other, causing chest pain and other symptoms.

Understanding the causes of pericarditis is crucial for effective diagnosis and treatment. While infections are the leading culprits, a variety of other factors can contribute to this condition, highlighting the importance of a thorough medical evaluation.

Common Causes of Pericarditis

Infections

Infections are the most frequent cause of pericarditis, responsible for a significant majority of cases. Among infections, viral causes are the most prevalent.

Viral Infections

Viruses are by far the most common cause of pericarditis, especially in developed countries. Several types of viruses can infect the pericardium and trigger inflammation. These include:

• Coxsackieviruses: These are a group of enteroviruses that are frequently implicated in viral pericarditis.
• Adenoviruses: Common viruses that can cause respiratory illnesses and sometimes pericarditis.
• Influenza viruses: The viruses responsible for the flu can also lead to pericardial inflammation.
• Echoviruses: Another type of enterovirus that can affect the heart.
• Cytomegalovirus (CMV) and Epstein-Barr virus (EBV): These viruses, known for causing mononucleosis, can also be associated with pericarditis.

Viral pericarditis often follows an upper respiratory infection, and symptoms may appear a week or two after the initial illness.

Bacterial Infections

While less common than viral causes, bacterial infections can also lead to pericarditis. These are often more severe and may require more aggressive treatment, typically with antibiotics. Bacteria that can cause pericarditis include:

• Staphylococci: Often associated with bloodstream infections or infections following heart surgery.
• Streptococci: Can cause pneumonia and other infections that may spread to the pericardium.
• Tuberculosis (TB): Tuberculous pericarditis is a serious form of the disease, particularly in regions where TB is endemic. It can lead to constrictive pericarditis if not treated promptly.
• Pneumococci: Commonly cause pneumonia and ear infections.

Bacterial pericarditis can arise from direct spread from a nearby infection (like pneumonia) or through the bloodstream.

Fungal Infections

Fungal pericarditis is rare, occurring primarily in individuals with weakened immune systems, such as those with HIV/AIDS or undergoing chemotherapy. Fungi like Candida, Aspergillus, and Histoplasma can infect the pericardium.

Autoimmune Diseases

Autoimmune diseases occur when the body's immune system mistakenly attacks its own healthy tissues. The pericardium can become inflamed as part of a systemic autoimmune process. Conditions that can cause pericarditis include:

• Systemic Lupus Erythematosus (SLE): Lupus is a chronic autoimmune disease that can affect various organs, including the heart and its surrounding sac.
• Rheumatoid Arthritis (RA): This inflammatory disorder primarily affects joints but can also involve the pericardium.
• Scleroderma: A connective tissue disease that can cause thickening and hardening of the skin and internal organs, potentially affecting the pericardium.
• Sarcoidosis: An inflammatory disease that can affect multiple organs, including the lungs and heart.

Other Medical Conditions

Several other medical conditions can contribute to the development of pericarditis:

• Kidney Failure (Uremia): When the kidneys are unable to filter waste products from the blood effectively, a buildup of toxins (uremia) can irritate the pericardium, leading to uremic pericarditis. This is more common in individuals with chronic kidney disease, especially those on dialysis.
• Cancer (Malignancy): Cancer can spread to the pericardium (metastasis) from other parts of the body, such as the lungs, breast, or lymphomas. This is known as malignant pericarditis.
• Heart Attack (Myocardial Infarction): Inflammation can occur in the pericardium covering the damaged heart muscle after a heart attack. A specific type, Dressler's syndrome, is a delayed form of pericarditis that can occur weeks to months after a heart attack or heart surgery.
• Thyroid Disorders: Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) have been linked to pericarditis, often as part of a broader autoimmune process.

Trauma and Medical Procedures

Direct injury to the chest or procedures involving the heart can also cause pericarditis:

• Chest Trauma: A blow to the chest, such as from a car accident or a fall, can injure the pericardium and lead to inflammation.
• Heart Surgery: Inflammation of the pericardium is a common complication after cardiac surgery, often referred to as post-pericardiotomy syndrome.
• Other Medical Procedures: Procedures like cardiac catheterization, pacemaker insertion, or biopsies of the heart muscle can sometimes irritate the pericardium and cause inflammation.

Medications

Certain medications have been identified as potential triggers for pericarditis. This is often an immune system reaction to the drug. Examples include:

• Procainamide and Hydralazine: Medications used to treat heart rhythm problems and high blood pressure, respectively.
• Isoniazid: An antibiotic used to treat tuberculosis.
• Certain Chemotherapy Drugs: Some cancer treatments can cause pericardial inflammation.
• Anticoagulants (Blood Thinners): While not a direct cause of inflammation, bleeding into the pericardial space can occur, which can mimic or exacerbate inflammatory symptoms.

Idiopathic Pericarditis

In a significant number of cases, the exact cause of pericarditis cannot be identified, even after a thorough medical investigation. This is known as idiopathic pericarditis. It is believed that many cases of idiopathic pericarditis are actually due to an unrecognized viral infection.

Diagnosis and Importance of Identifying the Cause

Accurately identifying the cause of pericarditis is essential because the treatment varies depending on the underlying reason. For example, viral pericarditis might be managed with rest and anti-inflammatory medications, while bacterial pericarditis requires antibiotics, and pericarditis due to autoimmune disease may necessitate immunosuppressive therapy.

A doctor will typically take a detailed medical history, perform a physical examination (listening for a pericardial friction rub), and may order tests such as an electrocardiogram (ECG), echocardiogram, chest X-ray, blood tests (to check for signs of infection, inflammation, or kidney problems), and sometimes a pericardial fluid analysis if fluid is present.

If you experience sudden, sharp chest pain that worsens when you lie down or breathe deeply, it's important to seek medical attention promptly to rule out pericarditis and other serious heart conditions.