An inflammation of the connective tissue of the heart’s protective layer can have many causes. The pericardium (peri = around; card = heart-related) surrounds the heart muscle as a protective sheath of connective tissue. It consists essentially of two layers, with only the inner firmly adhering to the outside of the heart muscle, thus being displaced during the pumping work against the outer layer. Inflammation of the pericardium can act as an independent disease or concomitant reactions of other processes in the organism.
The most common cause is an infection – usually with viruses, rare bacteria and other pathogens. Also rheumatic fever as a complication of infection with certain bacteria (streptococci) can cause pericarditis, which in many cases the endocardium and the heart muscle itself (the myocardium) are also affected. This leads to an incorrect response of the immune system where the defense against the body’s own tissue – in this case, cardiac tissue – is directed and causes inflammation there.
A similar thing happens in other autoimmune diseases such as rheumatic disorders of the musculoskeletal system and hypersensitivity reactions to drugs, for example. Not infrequently pericarditis occurs after a heart attack, which in a late form is delayed for two to three weeks later, or within 24 to 48 hours after the infarction in an early form. Further causes of pericarditis come due to hypothyroidism, renal insufficiency, connective tissue of the organism, and also from growing tumors in the chest or as a result of heart surgery. In 20 to 30 percent of cases no clear cause can be found.
As with any inflammation of the pericardium where increased blood flow to the tissue structures involved goes hand in hand, inflammatory cells from the circulating blood accumulate in the tissue and increasingly release tissue water. Whether and to what extent there are any symptoms depends on whether there is only inflammatory deposits in the contact area of the two Pericardial layers or whether the pericardium fluid builds (effusion).
In the first case – a so-called dry pericarditis – symptoms include breath-related chest pain, which typically increases in bed and when coughing. In the second case, the fluid in the pericardium can hinder normal relaxation and blood filling of the heart muscle so that cardiovascular function is impaired (cardiac tamponade) – signs are physical weakness, difficulty breathing and abdominal pain.
In the worst case, there is a circulatory shock. A basic distinction between acute and chronic pericarditis is that in the acute form heals after a single treatment and chronic pericarditis involves liquid that is continuously accumulated in the pericardium. Both forms can run mild or – as described above – manifest pericardial effusion to acute life-threatening situations. However, in the acute form the fluid accumulation is usually more serious because it is very strong (sometimes up to one liter) and develops so fast that the heart can no longer compensate for this. Obstruction of cardiac function by cardiovascular shock with fatal outcome can be the result.
Chronic pericarditis can lead to a deformed shape of the heart, in which the pericardium shrinks and is scarred, losing its elasticity and covers the heart like a rigid sheath due to recurrent inflammation.