DISEASES OF THE GREAT VESSELS. 



co proceed from the larynx, and comes on in paroxysms. Dyspnoea is 

 one of the most common and distressing symptoms of aneurism. 



A second set of signs proceeds from compression of the right auri- 

 cle, the vena cava, or the vena anonyma. If the auricle or vena cava 

 be compressed, the jugular veins swell, blue networks of veins appear 

 upon the skin of the chest, the veins of the arms become distended 

 with blood ; indeed, it is not uncommon for dropsy soon to develop in 

 the upper half of the body. The patient may complain of headache, 

 dizziness, buzzing in the ears, and fits of unconsciousness may be ob- 

 served. If but one of the vena innominata be compressed, the venous 

 dilatation is limited to the corresponding side of the head and chest. 



In consequence of the pressure and strain to which the intercostal 

 nerves and brachial plexus are subjected, most violent pain often arises 

 in the right side of the chest, the armpit, and right arm. Like most 

 other of the troubles to which aneurism gives rise, this pain is often 

 paroxsymal, and may deprive the patient of his sleep, and is reckoned 

 by Lauth among the agents which tend to produce speedy death by 

 exhaustion. 



Compression of the arteria innominata, or of the left subclavian, 

 may render the radial pulse extremely small or quite imperceptible. 

 Inequality between the pulsations at the wrist of either side may also 

 be a result of distortion of the arterial mouths, or of their stoppage by 

 clots. 



To these symptoms of compression of adjacent organs, are added 

 those of retarded circulation. Foremost among the latter is the pause, 

 often so distinctly perceptible, which occurs between the beat of the 

 heart and the wave of the arterial pulse, at a point below the aneu- 

 rism. This phenomenon is most striking when the aneurism is sit- 

 uated between the points of origin of the great vessels of the arch. 

 The pulse is then felt later at one wrist than at the other ; or, if the 

 tumor involve the descending aorta, the pulse below the tumor cannot 

 be felt until after that of the upper extremity. 



As hypertrophy can only temporarily compensate the impediment 

 to the circulation, not only does palpitation eventually set in, such as 

 we encounter wherever the heart's action is overtasked, but the de- 

 rangement in the blood's distribution, so often described, finally is 

 established ; the arteries are ill supplied, the veins and capillaries are 

 gorged, and general marasmus and dropsy ensue. If the patient do 

 not die of disordered circulation or of embarrassed breathing, and 

 should he not succumb to some other intercurrent disease, the aneurism 

 finally bursts. It would be erroneous, however, to regard this mode of 

 termination as constant or even as the most common mode of death. 



When, after coming to the surface in the form of a tumor, it breaks 



