TEEATMENT OF ANEUEYSM. 279 



either the main trunk on the distal side of the aneurysm, or 

 one or more of the branches into which it may divide. In order, 

 however, that success may follow such a procedure it is necessary 

 that there should be no large branch given off by the vessel 

 between the sac and the point at which the ligature is applied. 

 Perhaps nowhere in the body is this anatomical requisite so 

 evident as in the case of the common carotid. Supposing an 

 aneurysmal sac to be formed on the proximal part of the vessel, 

 a distal ligature will effectually prevent the passage of blood 

 beyond the aneurysm, seeing that there is no branch into which 

 it can pass. Another disadvantage of a distal ligature, particularly 

 as seen in the limbs, is the liability of gangrene following upon the 

 occlusion of the artery. In instances of subclavian aneurysm 

 in which there is little chance of applying a ligature upon the 

 proximal side of the sac with any degree of safety, a distal ligature 

 is apt to cause death of the limb beyond, or failure in bringing 

 about a cure of the aneurysm. Therefore it has been considered 

 advisable to as it were perform distal ligation, but at the same 

 time to remove the part which has to be supplied with blood, by 

 an amputation at the shoulder-joint. 



Pressure has been known to cure many aneurysms, in fact it 

 may be one of nature's methods of bringing about the cessation 

 of the continued dilatation of the sac. From its anatomical 

 relation the aneurysmal sac may itself cause pressure upon the 

 artery feeding it on the proximal side, and thus diminish the 

 amount of blood passing into the sac, and so allow the deposition 

 of clot. 



This proximal pressure has been carried out by the surgeon, 

 but as a rule at a greater distance away from the sac than the 

 spot at which nature applies it. Hence in a popliteal aneurysm 

 digital pressure is best applied to the last part of the external 

 iliac or the first part of the common femoral backwards against 

 the horizontal ramus of the os pubis. If such pressure by the 

 finger is carefully applied, the return of blood through the 

 femoral vein will not be interfered with an advantage not 

 secured by the mechanical pressure of a tourniquet. 



