ARTERY, PATHOLOGICAL CONDITIONS OF. 



233 



after death or the removal of the limb, the 

 artery should, if possible, be always slit up 

 on the side opposite to that from which the 

 tumour springs. The appearances of inflam- 

 mation will probably depend on whether the 

 aneurism be recent or of long standing, and 

 obviously on whether it has been the result of 

 accident or disease. Also, if it be recent, the 

 aperture leading into the sac is generally well 

 defined, circular, and circumscribed, its edges 

 remarkably thin and fine : if, on the contrary, 

 it is old, the aperture is large, smooth, and so 

 even as to present an appearance as if the 

 lining membrane had been prolonged from the 

 artery into the sac. On cutting into the sac 

 some fluid blood is usually found, and always 

 a quantity in a state of coagulation. Besides, 

 there is always more or less of fibrine, the 

 remains of former coagula deposited in irre- 

 gular lamina?, and varying in colour from a 

 pale red or grey. The most external layers 

 are closely fastened to the internal wall of the 

 sac by means of large depositions of flaky 

 lymph, from which, however, they can be 

 separated by careful washing or maceration. 

 This lymph thickens the walls of the sac, and 

 imparts to them considerable firmness and 

 resistance. The sac, itself, is most generally 

 of an oval form, but to this there are some 

 exceptions, amongst which the occasional oc- 

 currence of a dissecting aneurism is the most 

 curious. This happens when the internal and 

 middle coats having ulcerated or given way, 

 the blood insinuates itself between the fibrous 

 and cellular coats, detaching them from each 

 other to a considerable extent, whence the dis- 

 ease has derived its name.* Such is an outline 

 of the appearances on dissection, but they will 

 avail little in explaining the nature of aneu- 

 rism, unless combined and compared with the 

 phenomena of the disease during life. 



And, in the first instance, it must be recol- 

 lected that the tumour is pulsatile, a quality 

 that proves the entrance of a quantity of fluid 

 blood, and its return back again into the artery 

 by the resistance or reaction of the sac. It was 

 this circumstance that principally led Fer- 

 nelius to believe and to teach that aneurism 

 consisted in a dilatation of all the coats of the 

 artery, inasmuch as he could not understand 

 how pulsation occurred if the tumour did not 

 possess an elastic covering, and moreover 

 imagined that if the blood was driven into a 

 sac otherwise constituted, it must of neces- 

 sity remain there and become coagulated. 

 It is, however, unnecessary now to discuss the 

 question as to whether the sac of an aneurism 

 possesses elasticity or not, when it is daily 

 observed that any tumour (an enlarged gland 

 for instance) situated on an artery, and re- 

 ceiving an impulse from the heart, may com- 

 municate the sensation of pulsation, provided 

 the skin and other elastic tissues covering it 

 are sound. Nay, farther, it may be remarked 

 that the pulsation of an artery, even with its 

 elastic coat uninjured, is much more apparent 



* Sec Dissections of Aneurism, by John Shekel- 

 ton, Dub. llosp. Hop. vol. iii. 



than real, and when felt ab externo, is greatly 

 influenced by the skin and its other coverings. 

 It is a fact too well known to every operating 

 surgeon to be for a moment controverted, that 

 an artery when exposed exhibits nothing like 

 the force of pulsation that it did before the 

 skin was divided ; sometimes it is difficult to 

 ascertain it satisfactorily at all. The late Pro- 

 fessor Todd has strongly pointed out this 

 circumstance in his case of axillary aneurism, 

 published in the third volume of the Dublin 

 Hospital Reports, where he says, " For some 

 time I could not be convinced that the feebly 

 pulsating vessel, to which the point of my 

 finger was applied, was really an artery of such 

 magnitude as the subclavian ;" and similar 

 observations could be adduced, if necessary, 

 from other sources. 



It is of little consequence, then, whether the 

 aneurismal sac possesses an elastic covering- 

 proper to itself or not, the resistance of the 

 external structures being sufficient to explain 

 the phenomenon of pulsation, and the impor- 

 tance of the integrity of these structures in the 

 progress and termination of the case is ex- 

 tremely interesting. If even a small quantity 

 of blood was thrown at each pulsation of the 

 heart into a yielding, unresisting bag, it must 

 of necessity remain there, and in a very short 

 space of time the accumulation would be 

 enormous ; but if there is a re-acting force 

 capable of returning a portion of this blood 

 and restoring it to the circulation, the accumula- 

 tion and consequent growth of the tumour will 

 be measured by the quantity of blood thus left 

 behind. The volume of blood sent into an 

 aneurismal sac must be proportioned to the 

 aperture through which it has to pass, while 

 the actual quantity lost must depend not so 

 much on this as on the non-resistance of it and 

 its coverings, and their incapability of return- 

 ing the fluid back into the circulation. Hence 

 the growth of external aneurisms is in general 

 rapid or slow according as they have existed a 

 greater or less length of time ; for in old aneu- 

 risms the aperture into the sac is generally 

 large, and the elasticity of the external coverings 

 is weakened by over-distension. 



The pathology of aneurism arranges itself 

 under two distinct orders, one having relation 

 to the open and bleeding artery, the other con- 

 sequent on the haemorrhage being internal. 

 This latter circumstance is interesting to the 

 surgeon, because the presence of the blood in the 

 limb, the position it occupies, and the pressure 

 exercised by it on the adjacent structures and 

 organs, very often form the most prominent and 

 important features of the disease, and nearly 

 as frequently cause the destruction of the patient 

 as the bursting and bleeding of the tumour. 

 But the consideration of this part of the sub- 

 ject does not immediately belong to the patho- 

 logy of the arterial system, to which these re- 

 marks are more particularly directed. To re- 

 turn, then, to the open or ruptured artery. The 

 condition of the vessel is scarcely different 

 from that of one wounded by a knife. It is a 

 bleeding artery, and the same principle that is 

 applicable to hemorrhage under any other 



