7. In Rare Cases Arteritis

In Rare Cases Arteritis gives rise to a partially or wholly purulent exudation, which may be recognized by the following appearances: a. The inner surface of the vessel sometimes distinctly exhibits a thin layer of purulent exudation, which is partially attached to the plug.

b. This exudation, which is discolored and loosened, undergoes a process of softening, both in its interior and at different points of its circumference, and is reduced into a puriform semi-fluid mass, or into a fluid exhibiting a corresponding degree of decoloration.

c. The inner and the circular fibrous coats are swollen, unusually succulent, of a somewhat yellowish color, loosened and stratified, and are distinctly infiltrated and permeated with the purulent exudation.

d. The whole of the lining membrane of the umbilical arteries of newborn infants is frequently found to be detached from the yellow membrane, which again is separated from the elastic coat by means of the exudation which is produced from the cellular sheath, and is, for the most part, accumulated between these coats.

e. The cellular sheath exhibits the above-named signs of inflammation in a highly developed form, having purulent exudation diffused over the tissue or accumulated in circumscribed foci.

This form of arteritis deposits, therefore, as appears from the above observations, a product which is either capable of coagulation and solidification, and of being metamorphosed into tissue, or is of a purulent character. The first of these forms is commonly termed adhesive, on account of the obliteration of the vessel to which it very usually gives rise; it is of much greater frequency than the other form.

In reference to the modes of termination and the metamorphoses of the products of this form, we must notice the following particulars:

1. Adhesive Arteritis

Adhesive Arteritis occasionally passes into resolution, as does more frequently adhesive phlebitis; the products of inflammation in the tissue of the coats of the artery are resorbed, while the plug is gradually dissolved, and taken up into the blood in a finely comminuted condition.

2. The Ordinary Termination

The Ordinary Termination is permanent and more or less complete obliteration, which, in its turn, gives rise to atrophy of the vessel. - The plug in the vessel gradually shrivels, being decolorized and converted into a fibroid string. When the plug has entirely filled the vessel, and is attached to the inner wall by means of one of the above-named structures, the coats of the vessel will be found to adapt themselves to its shrivelling, while the vessel closes around it into a solid cylinder. But where the plug has not completely filled the artery, and is only attached at some points to the wall of the vessel, or where the shrivelling and metamorphosis have been effected too rapidly to allow of the walls of the artery following the process uniformly, and the adhesions have therefore been drawn aside and partially loosened by the flow of blood, the obliteration will be incomplete. In these cases the artery is occupied by a fibroid cord or string, which closely adheres at certain points to the wall of the vessel, although free at all other parts, or is, at the same time, attached in different places by means of string-like structures or pseudo-membranous plates, so that the calibre is very much contracted, and the circulation, more especially in the smaller vessels, correspondingly impeded. In consequence of complete closure, the specific tissue of the artery, more especially the circular fibrous coat, very rapidly disappears, and the vessel becomes converted into a hard fibroid cord enveloped in cellular tissue.

Bony substance may be developed in this fibroid cord, which may be ossified over various extents of its surface.

3. Arteritis With Purulent Exudation

Arteritis With Purulent Exudation leads, in some few cases, to complete or partial suppuration - ulcerous destruction of the vessel. This occasions hemorrhage, which, according to circumstances, is either external or directed into the tissue - a result which very rarely occurs in spontaneous arteritis, although frequent in the suppuration arising in an artery after it had been tied.

Arteritis is very rarely fatal through the fever by which it is accompanied, or the various inflammations to which it gives rise in important organs. Inflammation of the umbilical arteries, when it extends to the peritoneum, often proves fatal through peritonitis. Spontaneous gangrene in the form of mummification, commonly known as gangrena senilis, is often produced during arteritis or occurs as one of its sequelae, when it attacks the trunk of a vessel belonging to a part of the body, which cannot be supplied by any collateral circulation. This result of arteritis, which is dependent on the closure and obliteration of the vessel, has been most frequently observed in the lower extremities in inflammation of the femoral arteries. It is a common cause of the fatal result of spontaneous arteritis.

General infection of the mass of the blood, as the consequence of the absorption of the products of arteritis into the blood, and of the secondary metastatic processes in the capillary system with which it is intimately connected, is, according to our experience, a very unusual phenomenon, and hence a very uncommon cause of the fatal termination of arteritis. Our own opinion is confirmed in reference to this point, by the concurrent testimony of other observers. (Hasse).

We have already endeavored to explain this rarity of the secondary processes, as compared with their frequency in phlebitis. We will here briefly observe, that this rarity must be referred to the greater susceptibility of the arterial blood for taking up inflammatory products which speedily give rise to coagulation and to obturation of the vessel, and to the circumstance that their reaction in the arterial current, being exhausted towards the capillaries in ordinary cases, hinders the general infection of the blood beyond the limits of those vessels. The inflammation of the veins accompanying an inflamed artery, which we have had very frequent opportunities of observing, does not appear to us always to possess the character of secondary phlebitis, occasioned by coagulation of the blood from its absorption of the products of arteritis, but rather to depend on the transmission of the inflammation from one vessel to another.

This arteritis is of very rare occurrence when compared with phlebitis.

It is occasionally an idiopathic affection, but more frequently it appears to be secondary (metastatic), as it occurs after different acute diseases. The causes on which it depends are frequently very obscure, but in some cases it may be referred to traumatic influences. The form of arteritis which is occasioned by operative agencies, such as ligature, torsion, etc, will, by the process of healing by which it is followed, constitute the subject of future remarks.