ANEURISM OF THE AORTA. 425 



regular vibrations, and inefficient irregular vibrations of the aortic 

 valves, which are transmitted to the aneurism. Generally speaking, 

 however, even when the aortic valves are healthy, a diastolic murmur 

 is heard above the aneurism, and not a normal diastolic sound. This, 

 probably, is due to the recoil of a blood-wave, or to the actual regurgi- 

 tation of blood from the aneurismal sac into the aorta, owing to the 

 narrowness and roughness of the aperture of communication. 



DIAGNOSIS. The diseases for which an aneurism is most liable to 

 be mistaken are carcinomatous tumors of the pleura and mediastinum. 

 Lake aneurism, the latter may encroach upon the interior of the thorax, 

 may compress and distort the adjacent organs, and, if in contact with 

 the aorta upon one side and with the thoracic wall upon the other, 

 may even present a circumscribed pulsating point and afterward a 

 pulsating tumor. Distinction between the two affections is based upon 

 the following points : 



1. Carcinoma of the pleura scarcely ever appears primarily, but its 

 occurrence is almost always consecutive to the development of cancer 

 elsewhere, particularly after extirpation of cancer of the breast. If the 

 etiological conditions for cancer of the pleura be absent, we may infer 

 the existence of aneurism with great certainty. 



2. Pulsation in a cancerous tumor of the thoracic wall never ex- 

 hibits any lateral dilatation, while an aneurism swells up visibly with 

 every beat. 



3. A systolic murmur may proceed from pressure of a cancer upon 

 the aorta, just as it may occur in any artery pressed upon by the 

 stethoscope ; but we never hear the double sound or double murmur 

 in cancer of the pleura, which is so common in aneurism. 



4. We rarely or never discover difference between the pulses at 

 the wrist, when a tumor presses upon the aorta. 



5. The symptoms of aortic aneurism just described are distin- 

 guished by alternate paroxysms and intervals. The symptoms of 

 cancerous tumors, on the contrary, are steady. 



The diagnosis between an aortic aneurism and an aneurism of the 

 innominata cannot be made with certainty. The symptoms ascribed 

 to the latter pressure upon the vena cava superior, upon the right 

 bronchus, the right bronchial plexus, feebleness and retardation of the 

 right radial pulse, dulness, pulsation, and a tumor in the right sterno- 

 clavicular region all occur in aneurism of the aortic arch. 



PROGNOSIS. Aortic aneurisms rarely recover. Cure has never 

 been observed in a case where the disease has been recognized. On 

 the other hand, life has sometimes been preserved for years, where 

 early exhaustion of the patient has not been brought about by debil- 

 itating treatment. 



