INFLAMMATION OF THE OUTER AND INNER LINING MEMBRANE: VALVE DISEASE.
Inflammation of the Pericardium (Peri carditis).—The position and character of the outer lining membrane of the heart have been briefly noted on p. 298. It has been pointed out that it is in a double layer, the layer in direct contact with the heart being separated by a slight interval from the outer layer, a small amount of serous fluid existing in the space. Now when the membrane becomes inflamed the blood-vessels enlarge, becoming more full of blood, in consequence of which thickening of the membrane takes place. There oozes from the vessels on to the free surfaces of the mem brane a fluid which coagulates—lymph; and thus the surfaces which oppose one another, instead of being smooth and glistening, become irregular and roughened because of the newly formed deposit. The two layers ought to glide easily and noiselessly over one another with the movements of the heart, but, owing to the roughening, friction is produced, and a grating sound may be heard on applying the ear to the chest over the heart. Part of the fluid from the over-full vessels is not coagulable—serum ; and it collects in the space between the two layers. It may become so abundant as to sepa rate the layers completely from one another, in which case, of course, friction ceases. In some cases its quantity is so great that the heart is actually surrounded by a bag of fluid, giving rise to what might be called dropsy of the heart. If the inflammation abates at this stage, the vessels of the inflamed membrane begin to recover their usual size, fluid ceases to escape from them, and then a process of recovery sets in, in which the fluid begins to be absorbed by vessels—both blood-vessels and lymphatic ves sels. The quantity of fluid surrounding the heart slowly diminishes till again the layers conic into contact, friction is again produced, and the sound of it again heard. Finally the roughened surfaces adhere and become firmly connected to one another, so that they become fused and a space between them no longer exists.
This is a species of cure, there is no doubt, hut the adhesion of the layers of the pericardium is too apt to lead to the development of dis ordered conditions of the heart at a later stage of the person's life.
Instead of taking a simple course like this, the disease may be complicated by the forma tion of matter in the sac of the pericardium, and may continue in a chronic form for a longer period than the acute attack lasts.
The cause of the disease may be simply ex posure to cold, or injury such as a wound would readily produce, or it may be due to the exten sion of inflammation from some other organ, like the lungs. Frequently, moreover, it occurs a complication in other diseases, specially acute rheumatic fever, disease of the kidneys, St. Vitus' dance, scarlet fever, pykemia, &c. In a case of rheumatic fever Ale inflammation usually does not only affect the outer lining membrane of the heart, but the inner as well.
Symptoms.—There are pain and tenderness in the region of the heart, and extending from that part to the left shoulder and down the left arm. Fever is also present, with loss of appetite and dry tongue. The patient wears a peculiar look of distress, has a dry cough, and a catch in the breath. The pulse is at first full and strong, but later quick and weak. When much fluid has accumulated in the sac the pressure it exerts on the gullet behind may produce diffi culty of swallowing. Rambling and delirium are occasionally present.
Death may result from the pressure of the accumulated fluid surrounding the heart—from the dropsy,—the heart being unable to continue its work under the burden; and then it is sud• den. Recovery in severe cases is usually and the difficulty of breathing, quick pulse, &a, disappear very gradually.
Besides these symptoms there are others whose value and meaning are only appreciated by those who have had a medical education. One s the friction sound, already alluded to, heard by applying the ear to the chest over the region A the heart, or by listening with a stethoscope, the instrument used for sounding lungs and heart. It is due to the rubbing of the inflamed surfaces of the membrane on one another. Other signs are obtained by percussion, as described on p. 359. The percussion is performed on the a clear, hollow sound being obtained when the chest is percussed over the lungs, the sound being dull when the tapping is Over the heart. The area indicated on Fig. 133, p. 297, as occupied by the heart will give out a dull sound; but where the pericardium is filled with fluid it will be caused to bulge out by its con tents, and the limits of dulness will thus become much more extensive, because the sac filled with fluid will give out a dull, dead sound. In this way a trained person may discover whether much or little fluid has been poured out by the inflamed membrane.