nd transported from the interior of the heart or of some vessel.
Thrombi occur as the result of an injury to the wall of the vessel or
may follow its compression or dilatation; they may result from some
alteration of the wall of the vessel by disease or by the retardation of
the circulation. These formations may occur during life, in the heart,
arteries, veins, or in the portal system. When a portion of fibrin
coagulates in one of the arteries and is carried along by the
circulation, it will be arrested, of course, in the capillaries, if not
before; when in the veins, it may not be stopped until it reaches the
lungs; and when in the portal system the capillaries of the liver will
prevent its further progress. The formation of thrombi may act primarily
by causing partial or complete obstruction, and, secondarily, either by
larger or smaller fragments becoming detached from their end and by
being carried along by the circulation 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 hemorrhagica, endocarditis,
phlebitis, puerperal fever, hemorrhages, etc. These concretions may form
suddenly and produce 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
fragments 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 develop.

_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.

_Path