How Pericardial Effusion Develops

Pericardial effusion occurs when excess fluid accumulates in the pericardial cavity—the space between the heart's visceral and parietal layers. While some cases of pericardial effusion have identifiable causes, others remain unexplained and are referred to as idiopathic pericardial effusion. Inflammation of the pericardium, known as pericarditis, often plays a key role in the development of this condition.

Infectious Causes

Viral, bacterial, or fungal infections can invade the pericardium and trigger inflammation. When the pericardium becomes inflamed, it may produce excessive fluid, leading to a buildup known as pericardial effusion. These infections are among the most common causes of acute pericarditis and subsequent fluid accumulation around the heart.

Heart Failure and Fluid Retention

Another significant contributor to pericardial effusion is heart failure. In cases of chronic heart failure, the heart's inability to pump blood efficiently can lead to increased pressure in the cardiac chambers. This pressure can cause fluid to leak into the surrounding pericardial space, resulting in effusion. Additionally, systemic fluid retention associated with heart failure can exacerbate this process.

Radiation Therapy and Cardiac Damage

Radiation therapy for cancer, particularly when directed at the chest area, can damage the pericardium over time. This damage may result in radiation-induced pericarditis, which can lead to chronic inflammation and fluid buildup around the heart. Patients who have undergone thoracic radiation therapy are at a higher risk of developing pericardial effusion, sometimes years after treatment.