ANEURISM. 



Definition. Divisions, true, false, dissecting, arterio-venous, mixed, 

 traumatic, spontaneous. Causes, violence, rupture, debilitated vascular 

 walls, strains, stretching, force of blood current, overloaded intestine, strou- 

 gyli, contiguous inflammation, embolism, microbian invasion of the walls, 

 arteritis, concussion. Symptoms, soft tumor pulsating with the heart, a 

 double rushing sound, diagnosis from abscess, nervous disorders through 

 pressure, cramps, palpitations. Treatment, when desirable, rest, moderate, 

 laxative diet, iodides, bromides, icebags, compression, ligature, galvano- 

 puncture, wire coils, injections. 



Definition. A pulsating swelling on an artery, consisting of a 

 sac filled with arterial blood. 



Divisions. A true aneurism (aneurism by dilatation, ar- 

 teriectasis) is a simple dilatation of the artery, the tumor being 

 surrounded on all sides by the distended arterial walls. It is 

 usually fusiform or cylindroid, but may have the form of a more 

 or less rounded sac. 



A false aneurism is where the wall of the artery has been 

 lacerated and the blood is enclosed in an adjacent sac of con- 

 densed connective tissue and communicates • with the interior of 

 the vessel. The same name has been given to cases in which the 

 inner coat only has given way, and the middle and outer coats 

 constitute the walls of the sac. From its liability to extend and 

 separate the tissues this is further known as a dissecting aneur- 

 ism. Arterio-venous aneurism in which an intervening sac 

 communicates with both artery and vein, has been found in the 

 human subject. 



Mixed aneurisms are those in which a dilatation of the artery 

 is complicated by the presence of an outside pouch. 



A distinction has also been made according to origin into 

 traumatic and spontaneous. The former is of necessity false, 

 whereas the latter may be false or trjie. 



Causes. Apart from rupture of the arterial coat by direct vio- 

 lence, the common cause is a debility and loss of resistance in the 

 walls. In horses a far larger proportion of aneurisms are deep- 

 seated than in man, in whom forced muscular effort is less com- 

 mon. Yet even in horses the most common seat — the posterior 

 aorta — is liable to overstretching and to inflammation and soften- 

 ing by reason of contiguity to dorsal sprains. The posterior 

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