1. Redness And Injection

In order that these conditions may be regarded as the manifestation of inflammation, it is necessary that the former should be the result of the latter (inflammatory injection or stasis), or that it should depend on an exudation containing haematin into the tissue. This latter form of redness is always found together with other signs of inflammation, and usually presents a mottled appearance. Where the redness cannot be referred, at least in part, to the above cause, it cannot be regarded as a sign of inflammation. Now, in point of fact, all the different forms of redness of the endocardium, which have been generally described as characteristic of endocarditis, belong to the latter class, and the descriptions given of these various forms evidently show that they are mere modifications of that redness which depends on infiltration of the tissue with haematin. There are, however, so few opportunities of detecting the peculiar redness of the endocardium arising from an injection, as our own numerous observations can testify, that it would not be surprising if anatomists, instead of committing an error of this nature, had wholly denied the existence of inflammatory redness in endocarditis. It is only in the first stage of the disease that a true redness and injection can be observed through the endocardium; it is only, therefore, in the very rare cases in which death occurs in the earliest stage, either from this or some other disease, that this condition of redness can be perceived. In most cases a redness from imbibition, resulting from the diseased condition of the blood, is actually present, and renders it extremely difficult and almost impossible to discover the redness from injection, which differs wholly from the above-named red colorations, and is constantly of a pale, rose-red color, whose tint is subdued by the endocardium covering it. Its appearance is never that of a saturation of the tissue, and its stripe-like, ramifying course, corresponding to that of the vessels, may the more easily escape detection, when it is concealed by the presence of a simultaneous red coloration, arising from infiltration. In most cases we are unable to perceive this redness from the circumstance of its being wholly masked by the conditions we are about to consider, viz.:

2. Opacity And Thickening Of The Endocardium

In consequence of the extension of the process, the endocardium at various differently-sized spots is rendered opaque, whitish, and milky, whilst at the same time it becomes more or less thickened and swollen. This opacity and thickening depend on the deposition of the product of inflammation in the tissue of the endocardium and the subjacent stratum, where it either solidifies or exerts a relaxing, macerating, solvent action on that tissue. The opaque and thickened parts are not clearly defined, but appear gradually to lose themselves in the adjacent portions of the endocardium. Valves affected by endocarditis exhibit a remarkable degree of thickening, because the substratum of infiltration - the tissue occurring between the two lamellae of the endocardium - is here accumulated in large quantity. The shining smooth appearance of the endocardium vanishes with the increase of the opacity and thickening, and it then acquires a dull, velvet or felt-like and rough surface.

3. The Whole Of The Lining Membrane

The Whole Of The Lining Membrane of the heart acquires a looseness of texture, and then readily admits of being torn, while the true endocardium is easily detached. In inflammation of the valves, their fibrous tissue very frequently appears to be in an extreme state of looseness and relaxation.

4. Products Of Inflammation

To this class belongs the above-named infiltration of the endocardium and of the subjacent tissue, but the question here arises, whether there is also exudation on the free surface of the endocardium, and how far such a condition is necessary to establish the existence of endocarditis.

The fact of such an exudation being deposited on the free surface of the endocardium in most cases of endocarditis, is rendered highly probable, not only from the results of pathological investigations, and the analogy presented by inflammations of other similar structures, especially the serous membranes, but still more so from the symptoms manifested during life. This exudation at the moment of its production merges into, and is taken up by the mass of the blood, where, in accordance with its character and intensity, it gives rise to the different general symptoms manifested during life, and to the characteristic secondary processes observed in the capillary system in endocarditis. In many cases, however, this exudation, doubtless in consequence of a very high degree of coagulability, remains on the inner surface of the endocardium in the form of a membranous coagulum, having a delicate felt-like, or shaggy free surface, which we have rarely an opportunity of seeing in its original condition, but which may very frequently be subsequently observed under different forms, but most distinctly in the form of milk-spots on the endocardium. In endocarditis of the valves it commonly manifests itself in the form of felt-like or granular masses, under which the valve appears rough, loose in its texture, and excoriated, and it then, in part, constitutes the so-called vegetations of the valves of the heart. We shall subsequently speak of purulent exudation on the endocardium.