Pericarditis is the term for inflammation of the pericardium, the sac surrounding the heart and root of the great blood vessels. This protective sac has two layers, between which is a small amount of pericardial fluid that helps with lubrication. Pericarditis may arise as a result of an infection, autoimmune conditions, trauma, certain heart diseases, metabolic disorders, tumors or drugs. A significant number of pericarditis cases are due to unknown causes (idiopathic).
Pericarditis may be acute or chronic in nature. It often co-exists with myocarditis, which is inflammation of the neighboring muscular layer of the heart known as the myocardium. The pericardium is a secretory lining, contributing to the approximately 30ml to 50ml of pericardial fluid between the two linings (pericardial cavity). With inflammation, there is usually some additional fluid accumulation in the pericardial cavity and this is known as a pericardial effusion. It may contain a number of solid and fluid components that is reminiscent of the disease process or the causative factor.
Types of Pericarditis
Irritation of the pericardial lining gives rise to an accumulation of serous fluid in the pericardial cavity containing some inflammatory infiltrate like lymphocytes. The serous fluid is sterile and is usually not associated with infection of the pericardium itself. However, serous pericarditis may arise with irritation of the pericardium secondary to infection of surrounding structures like the pleura of the lungs (pleuritis). It may gradually progress to a serofibrinous exudate, or purulent or hemorrhagic effusions depending on the nature and duration of the cause. The effusion is often straw-colored and contains protein.
This type of pericarditis leads to a drying of the pericardial cavity as fibrin in the serous fluid (serofibrinous) eventually becomes organized. The extent of adhesion formation may vary. Fibrinous pericardiatis is usually not related to an infection although it may arise with chronic infections. It has a number of causes, including heart disease, injury to the heart, after cardiac surgery or due to autoimmune diseases.
This type of pericarditis is also known as suppurative pericarditis and arises as a result of an infection. The invading pathogens may reach the heart through a number of routes including direct spread from neighboring sites (lungs, pleura), spread through the blood stream or lymphatic system, or direct infection seen with cardiothoracic surgery or penetrating injuries of the chest wall. It is more often seen with bacterial infections.
This indicates the presence of blood in the pericardial effusion and may be seen in the backdrop of fibrinous or purulent pericarditis. This means that hemorrhagic pericarditis may arise with both infectious and non-infectious causes but the concern is often about malignant conditions (cancer of the pleura, breast, bronchus or lymphoma).
Other Types of Pericarditis
Granulomatous pericarditis may be seen with certain diseases like tuberculosis (TB), fungal infections, sarcoidosis or rheumatoid arthritis. It may progress to constrictive pericarditis over time where cardiac functioning is impaired due to a thick casing forming around the heart that limits cardiac expansion during diastole.
Another type of chronic pericarditis which results in severe damage and degradation of the pericardium is known as adhesive pericarditis. Cardiac functioning is not affected in adhesive pericarditis but the workload on the heart may be increased. It may be seen after infections, persistent inflammation, following cardiothoracic surgery or exposure to radiation.