Pericarditis

Excerpt

The pericardium is a double-layered, fibro-elastic sac surrounding the heart. It consists of a visceral layer overlying the epicardium, and a richly innervated parietal layer, separated by a potential space which normally contains 15 to 50 mL of serous fluid. The term “pericarditis” refers to inflammation of the pericardial sac and represents the most common pathological process involving the pericardium. Temporally, it may be further classified into acute pericarditis, incipient/subacute pericarditis, chronic pericarditis and recurrent pericarditis, which is estimated to occur in 30% of cases. Pericarditis may also be associated with other pericardial syndromes, such as pericardial effusion, cardiac tamponade, constrictive pericarditis, and effusive-constrictive pericarditis. .

Frequently, pericardial inflammation can be accompanied by increased fluid accumulation within the pericardial sac forming a pericardial effusion, which may be serous, hemorrhagic or purulent depending on etiology. This fluid accumulation may become hemodynamically significant, particularly when the pericardial effusion is large, or rate of accumulation is too rapid, as the fluid can extrinsically compress the cardiac chambers limiting diastolic filling and causing the syndrome of cardiac tamponade. This can present with obstructive shock and is considered a medical emergency requiring immediate intervention. Additionally, pericarditis may be followed by pericardial thickening, which can rarely present as constrictive pericarditis months or even years after the initial insult has passed. A more recently described entity called effusive-constrictive pericarditis", occurs when there is fluid accumulation around the heart, but constrictive physiology (such as respiratory enhanced interventricular dependence, restrictive E/A filling pattern, mitral annulus reversus with septal e' > lateral e', etc...) is displayed even after pericardiocentesis is performed marking constrictive pathology independent of the presence of a pericardial effusion.

The aforementioned pericardial syndromes may be seen in association with acute pericarditis, but are not a prerequisite for the diagnosis, and will be discussed in more detail elsewhere.