Elements of Surgery. Robert Liston

somewhat similar to that produced by the artificial application of a ligature. Coagula are seldom formed in the dilated vessel, to whatever size it may be enlarged, unless there is fissure of the internal coat; for in no other way can a portion of the blood readily become stagnant, while the calibre of the vessel remains pervious. There is in my collection a preparation of dilated aorta, to the coats of which adheres a large firm coagulum. Occasionally, though rarely, a dilatation of the internal coats is met with accompanied by thinning of the external ones. Of this sort of diverticulum, there is also a good specimen in the collection here alluded to.

      A spontaneous cure may also be accomplished from the original aneurism being compressed by one of a more recent origin, causing ultimate obliteration of the canal. Of this I recollect one remarkable instance; the patient was afflicted with an aneurism of the axillary artery, which had attained a large size, and the cure for the disease in this situation being then unknown or unattempted, the patient was considered as lost; but some time after the tumour began to diminish, and disappeared. The patient died; and the cause of death was found to be the giving way of an aneurismal tumour of the arteria anonyma, which was situated so closely to the aneurism of the subclavian as to have acted as a mechanical compress, causing obliteration of the vessel at that point.

      When a cure has been effected, the vessel is found to be converted into a dense and impervious cord at the site of the tumour. The canal above is dilated; the coats are thickened, especially the middle; and from the thickening and increased action of the fibres, the internal coat becomes somewhat rugous, the rugæ being in a transverse direction.

      The aneurismal tumour in general increases, and approaches the surface, involving and destroying all the intervening textures. If resisted in its enlargement by bone, even this is not sufficient to impede its progress; the bone is absorbed, and perhaps ulcerated, at the point where it is compressed by the tumour. The osseous is more liable to destruction from this cause than the cartilaginous tissue, contrary to what occurs from compression by abscess. Ultimately the sac gives way, and its contents are discharged either externally, or into an internal cavity or canal, in consequence of its parietes sloughing from the compression made by the tumour; and such termination is instantly fatal.

       An aneurism of the descending aorta, in a great measure one from dilatation, is here represented: the patient also laboured under popliteal aneurism of one limb, and inguinal of the other. He died suddenly, in consequence of the giving way of the internal tumour. The escape of blood into the cellular tissue may even take place to such an extent as to prove fatal in a few hours. The disease may also prove fatal by mere compression, as of the trachea, impeding breathing, and inducing disease of the respiratory organs; or by pressure on the gullet preventing the passage of food: in the latter case, however, the dissolution is generally more sudden, in consequence of the compressing part of the tumour giving way, and the contents being evacuated into the stomach or mouth. If the aneurism compress a plexus of nerves, or the spinal chord itself, the anterior part of the vertebræ having been previously absorbed, paralysis is produced.

      In consequence of aneurism, the circulation of blood in the vessel is obstructed; hence the collateral branches above the tumour become enlarged, and through them the circulation is continued; by their anastomosis with collateral branches which arise below the seat of the tumour, a portion of the fluid is brought back into the canal of the original artery. The circumstance of collateral enlargement used to be distinctly enough demonstrated in amputation, one of the old cures for the disease.

      The tumour may be suddenly increased by a portion of the parietes giving way, and the blood being propelled into the cellular tissue, which becomes thereby condensed, and supplies the deficiency in the original sac; diffuse is thus superadded to the true or encysted aneurism.

      The disease is generally accompanied with great pain, the neighbouring nerves being much stretched by the enlargement of the tumour, as in the axilla or ham; in these situations also the limb below the aneurism is much swollen from the compression of the absorbents and veins and consequent infiltration into the cellular tissue. Diffused aneurism from wounds, and the other species of the disease, will be afterwards treated of.

      The peculiar degeneration of the coats of the vessels has been already stated to be the predisposing cause of aneurism; and the disease may be directly caused by over-excitement of the circulation, or by an over-exertion of the muscles. It is more frequent in males than females.14 In men somewhat advanced in life the arteries get hard and rigid, whilst at the same time the muscles are strong, the general health good, and the whole frame stout and active; so that the patient is capable of violent muscular action, such as the arteries are ill able to bear, and consequently the internal coat of a vessel yields, and lays the foundation for an aneurism.15 The lower limbs being chiefly subject to such exertions, aneurism in them is most frequent;16 and for the same reason it is said to be common in those who ride much on horseback. Degeneration of the coats of the vessels in the superior extremity is extremely rare. This is another reason why spontaneous aneurism seldom assails them.

      Treatment.—In internal aneurism the only indication which can be followed, with any chance of success, is to favour the occurrence of a spontaneous cure, by abstracting all stimuli, mental and corporeal, by enjoining complete rest, by keeping the patient on low diet, and by repeated bleeding. Thus the force of the circulation is diminished, and coagulation, it is said, promoted; by this practice aneurisms, the progress of which defies external means, are occasionally, though very rarely, cured. Ice and other cold applications to external aneurisms, or those which have made their way to the surface, have been recommended to induce coagulation, but their use is not unattended with danger; for they may, in some stages, so far diminish the vitality of the coverings as to cause sloughing, and fatal hemorrhage.

      In the treatment of aneurisms exterior to the great cavities, important improvements have been made in modern times. No success can be expected to follow palliative and temporizing measures, and a cure can result only from operation. Formerly it was the practice to lay open the aneurismal tumour, to search for the extremities of the artery opening into the cavity, and to secure them by a ligature, or close them by pressure, styptics, or both. In some few instances this method had permanent success; but in the majority the operation proved wholly abortive, and not unfrequently fatal. It was necessarily tedious in its performance, and attended with much danger, the blood being discharged in great profusion immediately after the opening of the sac, and the extremities of the vessels being with great difficulty detected and secured. Besides, the vessels in the immediate neighbourhood of the tumour having generally undergone the degeneration already mentioned, were incapable of taking on any healthy action; the application of ligature on a vessel thus circumstanced could consequently be productive of no advantage. From this method having almost invariably proved unsuccessful, practitioners in those days generally preferred amputation, when the tumour was so situated as to allow it; and when the disease occupied a situation in the limb so high as to prevent amputation, the case was deemed incurable, and the patient abandoned to his fate. But amputation was accompanied with circumstances almost equally alarming with those attendant on division of the sac: the hemorrhage was very great; for as a consequence of obstruction to the free passage of the blood in the aneurismal vessel, the circulation was chiefly carried on by the collateral anastomosing branches, which were thereby so much enlarged, as, on their division, to pour out blood with a profusion resembling that of arteries of the second or third magnitude. Continued pressure was employed as a less hazardous method of cure, but was equally inefficacious; and was also attended with danger, from the risk of sloughing. If the practice ever proved successful, it was only after a tedious perseverance in its use, and long confinement of the patient.

      The operation of applying a ligature on the vessel at a distance from the tumour, and thus intercepting or weakening the flow of blood into the cavity, so as to allow complete coagulation to take place, is of comparatively modern invention, and is the one now practised with almost invariable success. To John Hunter without doubt belongs the merit of proposing and putting it in practice; it has been claimed also for the celebrated Desault. This operation has been variously modified. Some have advocated the temporary application of a ligature, conceiving that the effects produced will be as complete and permanent when it has been allowed to remain only