The diseases of the pericardium, with a few exceptions, belong to the inflammatory variety, and, as a rule, are the consequences or accompaniments of other inflammatory diseases of the circulatory system or of parts near the heart. The most common of the pericardial affections is pericarditis, which may be simple or secondary, and acute or chronic.
Pericarditis may occur upon either the visceral or the parietal layer of the membrane, and may attack any portion or several or all parts at the same time, being thus circumscribed or general. Usually, the whole or a large part of the pericardium is affected. Pericarditis is further characterized by effusions or exudations, which may be either fluid or semi-solid, and in consequence of the varied character of these exudations subdivisions are often made, such as the serous, fibrinous, sero-fibrinous, purulent, sero-purulent, and hemorrhagic forms. Pericarditis is generally marked by an effusion of fluid, the exception being designated as dry pericarditis, in which serum or other thin exuded material is almost or entirely absent.
Simple acute or idiopathic pericarditis is comparatively rare, and some authorities doubt its existence, believing that the pericardial inflammation is always secondary, plausibly supposing that the primary affection has escaped detection. Bamberger and Hayden, for instance, are of this opinion. I am, however, certain that I have met with several instances of true acute idiopathic pericarditis. Cases of so-called simple pericarditis are really often due to injury. It may not be easy in many cases to determine the traumatic or other condition in which the apparent simple acute pericarditis originated. The weight of evidence is so much in favor of traumatism as a preceding and efficient cause of simple acute pericarditis that a diligent search should always be made for the same. But even these doubtful examples are comparatively rare; and pericarditis is in the vast majority of instances secondary, and not difficult to identify as such. By some, traumatic pericarditis is classed with simple pericarditis as a variety, although not idiopathic.
Inflammation of the pericardium is governed by all the laws which control inflammatory processes elsewhere, being either acute, subacute, or chronic. The subacute form probably exists frequently, but escapes detection on account of the latency of the symptoms. The acute form is the most readily recognized. If not relieved, it passes into the chronic disease, which may be of long duration. The passage from one kind to the other is so gradual as to make it almost impossible to determine when one stops and the other begins, though it may be stated that after an acute attack has continued for from two to three weeks the chronic form is established. The chronic affection may begin, however, insidiously, or develop out of the subacute variety.
CAUSES.—The causes of pericarditis are numerous, and range from simple cold and injuries to the thorax to those diseases of which it becomes a companion, whether the seat be remote from, or in immediate juxtaposition to, the pericardium. Simple cold as a cause of pericarditis is, as has already been indicated, very much questioned. Though a very rare, I believe it a possible, cause. Other causes of simple pericarditis may be blows upon the breast, as with the fist; crushing or compression, as in railway accidents; penetrating wounds, as from gunshot or knife; and injury from foreign bodies in the oesophagus, such as pins, false teeth, etc. Buist1 records a case of a man who swallowed a plate with artificial teeth attached. The plate, becoming lodged in the oesophagus, finally penetrated the pericardium posteriorly and produced fatal pericarditis. A similar case is recorded by Flint.2
1 Charlestown Medical Journal and Review, Jan., 1858.
2 Diseases of the Heart.
By far the most common form of pericarditis may be termed secondary, which, like simple pericarditis, may be divided into the acute and chronic forms. It is termed secondary or consecutive, because it follows as a result either of impoverishment of the system or a pre-existing disease, constitutional or local. There are, however, exceptions to this rule; for we meet with cases of secondary pericarditis in which pericarditis preceded the onset of, and then continued associated with, the other manifestations of the disease which determined it. We see this sometimes in the history of acute rheumatism.
The disease of the pericardium is often the result of contiguity, but is much oftener determined by constitutional causes. Why the pericardium should be the particular membrane selected to take on inflammation as a complication to other affections has baffled the best endeavors of the most careful inquirers to determine. The diseases affecting the pericardium by continuity or contiguity of texture are chiefly myocarditis, tubercle of the lung and mediastinal glands, cancer of the same structures, pleurisy, pneumonia, and cancer of the oesophagus. On fibroid disease of the heart pericarditis is a frequent attendant.3 The diseases affecting the pericardium by a special election, and which are remote from the membrane, are, principally, acute articular rheumatism, Bright's disease, inflammation and other diseases of the liver, phlebitis, typhus, typhoid and eruptive fevers, scurvy, and acute alcoholism. Without doubt, by far the most frequent cause of pericarditis is acute articular rheumatism. Pericarditis does not occur in chronic rheumatism, and it is doubtful whether it may be occasioned by gout, notwithstanding the decided and weighty opinion of Hayden that this is an efficient cause.
3 It was found in more than half the cases published by Fagge in Transactions of the Path. Soc. of London, vol. xxv.