The surgical pathology of the arteries presents itself in two different though equally interesting points of view, one having reference to the effects of a wound or other injury to a healthy vessel, embracing a consideration of the pro cess by which such injury is remedied or re paired by the efforts of nature alone or by the assistance of art, and the circumstances that influence its success or failure ; the other refer ring to the appearances and consequences of disease, either as it commences idiopathically within the vessel itself, or is propagated from adjacent parts or structures to it. A lesion of the structure of an artery is of but slight importance provided its function is unimpaired, that is, as long as the blood it was destined to circulate passes through it or is conveyed by some other channel in the natural course of the circulation : even the aorta has been obliterated without any serious inconvenience to the indi vidual in whom it occurred. But when the lesion is of such a nature as to interfere with this function, when the blood is allowed to escape either externally as from an open wound, or internally as in the different species of aneu rism, results of a most formidable nature ensue, greatly modified, however, in their cha racter and consequences by a number of cir cumstances highly deserving of attention.
Wounds and injuries (if arteries. — It cannot have escaped observation that the nature of the wound or rather of the substance that occasioned it exerts a striking influence on the phenomena both of haemorrhage and of the process by which it is restrained. Lacerated wounds seldom bleed, although the torn artery may be left hanging out an inch or more be yond the adjacent surface. Gun-shot wounds, also, if the artery is completely divided, are not often followed by haemorrhage, although some instances to the contrary occasionally happen ; but if the vessel is only notched or partially cut, the bleeding is as profuse as from any other cause. If an artery is wounded by a cutting instrument or by puncture, however, the blood is poured out most freely ; yet even here there are varieties, according to the size and importance of the vessel, the extent and direc tion of the accompanying wound, and the cir cumstance of the division of the artery being partial or complete. In like manner the sub sequent progress of the case will exhibit con siderable variety, and demonstrate the fallacious views of those who, grounding their opinions on experiment, would limit the process of recovery to one operation, and regard the efforts of nature as alike in all, whereas, as has been remarked by Mr. Guthrie, this process essen tially depends on the size and variation of structure of the artery ; it is not the same in large as in small arteries ; and it is not even quite the same in the upper and lower ends of the same artery.
.When a limb has been torn off by a cannon shot, by the fall of a tree on it, or by any simi lar violence, the arteries do not bleed : very frequently the main trunk is seen hanging an inch or more from the wound, pulsating, or at least receiving an impulse from the sound portion of the vessel, though (as far as I have observed) not containing blood within it. It
hangs white, bloodless, and flaccid in the wound, not very unlike a piece of narrow wetted tape, and is smaller at its extremity than at any other part. This narrow point, which, according to Mr. Guthrie, is formed by the contraction of the artery, is also in his opinion the only barrier to the escape of the blood ; for in a case of this description he cut off the end of the artery at less than an eighth of an inch from the extremity, when it bled with the usual vigour. The extraordinary op portunities this gentleman has enjoyed, and the accuracy of observation which his writings evince, entitle his opinions to be received with great deference although in a physiological point of view it is difficult to conceive how an artery subjected to such a lacerating force should not have its vital properties so much impaired as to prevent its contracting at all, more par ticularly at the spot where it was torn across, and where, therefore, the greatest injury was sustained. At the same time there is no other mode of explaining the case. All that portion of the artery that is pendulous from the wound appears to be smaller in diameter than in its healthy state ; there is cellular tissue at its torn extremity, but it is not injected with blood, and the coagulum, if any, within the vessel, is so small as to be incapable by its mechanical resistance of preventing the escape of the blood. As there are scarcely any two accidents at tended by exactly the same degree of injury, it is probable that nature in such cases possesses different resources. In one case where the leg had been torn off by the falling of a tree, and left attached merely by a portion of the skin over the gastrocnemius muscle, the posterior tibial artery hung nearly three inches from the wound. As the man had been carried a dis tance of eleven miles, and seemed much ex hausted, it was not deemed right to attempt more at the moment than merely to relieve him of the annoyance of the pendulous portion of the limb by cutting through the skin. This was performed incautiously, for no inconve nience was apprehended ; about an inch of the extremity of the artery was removed, and it bled just as in Mr. Gutheie's case. In another instance where the arm was shattered by a steam-engine with such violence that some of the muscles torn from their attachments re Q 2 mained upon the wheel, the artery, divided in the subsequent amputation more than two inches above the wound, did not pour out one drop of blood. In others, still, the cellular sheath of the artery has been seen injected with blood in a state of coagulation, the pres sure of which on its orifice seemed to be sufficient to prevent bleeding.