The formation, density, and organization of the lymph depends largely upon the cause of the pericarditis. The more acute the attack and the greater the constitutional disturbance, the more likelihood there is of rapid effusion of lymph and of its speedy organization, whether it form adhesions or not. Where the fibrin is exuded under the influence of a subacute or chronic disease, the formation will be slow, paler, less highly organized, softer, and if adhesions form they will be less strong.
The heart participates in the inflammation of the pericardium, and if it be for any time subjected to the presence of the fluid effusion its walls degenerate and a granular atrophy occurs. Besides this, in extensive and firm adhesions there is likely to be primary hypertrophy followed by dilatation, the walls being enfeebled by degeneration, and, it may be, becoming thinner. At first, the effort to overcome the pressure of the pericardial effusion produces the hypertrophy; then the more or less complete binding down of the walls of the heart, preventing complete systole and weakening their inherent elasticity, and the pressure upon the coronary vessels, depriving the heart of the blood necessary for its healthful existence, are the causes of the degeneration and wasting of the walls and of the dilatation of the cavities.
Pus in the pericardium, as a result of pericarditis, may appear very early in the inflammatory attack, or it may occur after the effusion of lymph and serum. It may happen but in small amounts smeared over the surface of the membrane, or be profuse in quantity. Pus may also arise from small abscesses in the tissue of the heart bursting through the pericardium. It may be the result of injuries to the pericardium or to the inflamed membrane, or it may originate in the migration and proliferation of the leucocytes of the blood. The microscope in doubtful cases gives us the best idea of their prevalence and quantity, as well as of the amount of blood-corpuscles present. Where pus alone exists it is yellow and creamy; but with an excess of serum or fibrin it may be thinner or thicker in consistence, the entire heart being bathed in the fluid.
The lesions of chronic pericarditis differ but little from the acute, except as to their inception or the initial stage. The change from the acute to the chronic form may occur in a very few days, or even in less time, and an autopsy would not reveal anything to determine the fact. Pericarditis in any form is apt to be associated with pleurisy, and adhesions between the pericardium and adjacent pleura are common. In some instances the distended sac is adherent to the back of the chest. By its pressure on the lung and the oesophagus it may produce secondary lesions in them as well as in the phrenic nerves.
SYMPTOMS.—The symptoms of pericarditis may be so slight as not to attract attention. Where they are noticeable we find pain or a sense of uneasiness or of pressure, with or without tenderness in the pericardial region. The pain or uneasiness is not infrequently accompanied by pain or tenderness in the epigastric region when pressure is made upon it. This arises from the contiguity of the part and the pressure of the diaphragm against the inflamed and tender pericardium. The pain is sometimes preceded by a chill of varying severity, and is followed by febrile symptoms of greater or less intensity; but these may be so slight as to escape observation altogether except by taking notice of the markings of the thermometer.
Yet the thermometric record, although indicative of fever, has nothing characteristic. It is, I think, more influenced by the conditions under which pericarditis happens than by the pericardial inflammation itself. Often the fever-curve is marked by decided remissions, and as the result of the pericarditis alone does not attain a high degree. In the aged, Charcot has pointed out that the temperature of the body is lowered in some instances of acute pericarditis. The setting in of pericarditis in acute rheumatism was observed by Lorain to depress the thermometric marking, and Brouardel has noted the same effect at the onset of pericarditis in typhoid fever.6
6 Constantin Paul, Maladies du Coeur, Paris, 1883, p. 130.
The action of the heart is increased in frequency and force, as indicated by observing the impulse and the pulse at the wrist. There may be present, in different degrees, difficulty of breathing or a sense of suffocation; difficulty in swallowing; also cerebral disturbance, as headache, dizziness, sleeplessness, mental depression, fear of impending death. Besides these we may meet with hiccough and nausea and vomiting. But any or all these symptoms may also occur in myocarditis and in endocarditis, and are therefore not of themselves diagnostic; they only serve as indicators of the direction in which to seek the cause of disturbance. Some of the latter symptoms may be so aggravated, particularly those manifested by the nervous system, that attention is absolutely diverted from the seat of the disease. Indeed, they are often very misleading; and I cannot even agree to Hayden's statement7 that with few exceptions the symptoms of pericarditis take precedence of the physical signs, though they cannot be regarded as sufficiently distinctive to warrant a positive diagnosis. Doubtless these symptoms, however suggestive of pericarditis, may be found to depend upon other causes. With so little, then, of a positive nature to assist us in our search, we should be always at great loss were it not for the physical signs.
7 Diseases of the Heart and Aorta.
PHYSICAL SIGNS.—The chief of these are determined by inspection of the chest, by palpation, by auscultation, and by percussion.