DISEASES OF THE ARTERIES. 245 



thrombi may act primarily l)y causing partial or complete obstruc- 

 tion, and, secondarily, either by larger or smaller fragments becoming- 

 detached from their end, and by being carried along by the circula- 

 tion of the blood to remote vessels, embolism; or by the coagulum 

 becoming softened and converted into pus, constituting suppurative 

 phlebitis. These substances occur most frequently in those affections 

 characterized by great exhaustion or debility, such as pneumonia, 

 purpura hemoi-rhagica, endocarditis, phlebitis, puerperal fever, 

 hemorrhages, etc. These concretions may form suddenly and i)i'0- 

 duce instantaneous death by retarding the blood current, or they may 

 arise gradually, in which case the thrombi may be organized and 

 attached to the walls of the heart, or they may soften, and frag- 

 ments of them (emboli) may be carried away. The small, wartlike 

 excrescences occurring sometimes in endocarditis may occasionally 

 form a foundation on which a thrombi may develo]). 



Symptoms. — When heart clot, or thrombus, exists in the right side, 

 the return of blood from the body and the aeration in the lungs is 

 impeded, and if death occurs, it is owing to syncope rather than to 

 strangulation in pulmonary respiration. There will be hurried and 

 gasping breathing, paleness and coldness of the surface of the body, a 

 feeble and intermittent or fluttering pulse, and fainting. When a 

 fibrinous coagulum is carried into the pulmonary artery from the 

 right side of the heart, the indications are a swelling and infiltration 

 of the lungs and pulmonary apoplexy. When the clot is situated in 

 the left cavities of the heart or in the aorta, death, if it occurs, takes 

 place either suddenly or at the end of a few hours from coma. 



Pathology. — AVhen a coagulum is observed in the heart it may be- 

 come a question whether it was formed during life or after death. 

 The loose, dark coagula so often found after death are polypi. If 

 the deposition has taken place during the last moments of life, the 

 fibrin will be isolatetl and soft, but not adherent to the Avails; if it 

 be isolated, dense, and adherent or closely intertwined with the 

 muscles of the papilla) and tendinous cords, the deposition has oc- 

 curred more or less remote from the act of dying. Occasionally the 

 fibrin may be seen lining one of the cavities of the heart, like a false 

 endocardium, or else forming an additional coat to the aorta or otlier 

 large vessels without producing much obstruction. Thrombi, in 

 some instances, soften in their centers, and are then observed to con- 

 tain a puslike substance. If this softening has extended considerably 

 an outer shell, or cyst, only may remain. The sources of danger exist 

 not only in the interruption of the circulation of the blood, but also in 

 a morbid state of the system, produced by the disturbed nutrition of a 

 limb or organ, as well as the mingling of purulent and gangrenous 

 elements with the blood. 



Treatment. — The urgent symptoms should be relieved by rest, 



