4:24 DISEASES OF THE GREAT VESSELS. 



may result from similar action upon the kidneys. If the aneurism bo 

 situated immediately beneath the diaphragm, the latter will be pushed 

 upward in a painful manner, and the heart will be dislocated upward 

 and outward. 



Physical Signs. As long as the aneurism remains enclosed within 

 the thorax, without touching its wall, diagnosis is not assisted by 

 physical examination. The respiratory murmur may, perhaps, be di- 

 minished upon one side or the other, or a constant whistling sound 

 over a compressed bronchus may be audible ; but such signs admit of 

 too many and too different interpretations to warrant our founding a 

 decided opinion upon them. 



When the aneurism touches the thoracic wall, upon inspection, we 

 can almost always perceive a distinct pulsation at the point of contact, 

 and this becomes still more evident upon palpation. The pulse is 

 isochronic with the beat of the heart, or follows close upon it. It is 

 usually stronger, also, and is almost always accompanied by a peculiar 

 whirring " fremissemenl cataire" The point at which pulsation ap- 

 pears in aneurism of the ascending aorta is usually on the right border 

 of the sternum at the second intercostal space. In aneurism of the 

 arch it is at the manubrium sterni ; in the descending aorta, it is seen 

 upon the left side of the lower thoracic vertebrae. Where the aneu- 

 rism has perforated the thoracic wall, inspection and palpation dis- 

 cover new symptoms. At first, one intercostal space projects in the 

 form of a hemisphere. The tumor soon extends, admitting of no ar- 

 test of its progress. It sits firmly and immovably upon the chest, and 

 fully conveys the impression that it has sprung from within the thorax. 

 Sometimes the hemispherical form afterward gives place to an irreg- 

 ular shape. In cases of great rarity, where there is an inordinate ac- 

 cumulation of clot hi the sac, there is no pulsation. 



Percussion is absolutely dull and flat all over the tumor, or over 

 the region where it lies in contact with the chest. The sense of re- 

 sistance upon percussion also seems considerably increased. 



Upon auscultation of aneurisms which lie in contact with the side 

 of the chest, we hear either a murmur or a simple or a double " tone." 

 Explanation of these symptoms is obscure. 



The main cause of the systolic murmur and systolic sound is vibra- 

 tion of the aneurismal wall. When the vibrations, into which the 

 atter is thrown by the entrance of the blood, are regular, a systolic 

 sound is the result ; when it is otherwise, there is a murmur. Perhaps, 

 too, a systolic murmur sometimes arises when the aorta or pulmonary 

 artery is compressed by the aneurismal sac, and when the blood enters 

 the aneurism from the aorta through a narrow aperture. Diastolic 

 sounds and diastolic murmurs are respectively the result of healthy 



