Embolus

“ Embolic Gangrene# (Fig. 21) .--This is the most typical form of gangrene resulting from the _sudden_ occlusion of the main artery of a part, whether by the impaction of an embolus or the formation of a thrombus in its lumen, when the collateral circulation is not sufficiently free to maintain the vitality of the tissues.
There is sudden pain at the site of impaction of the embolus, and the pulses beyond are lost. The limb becomes cold, numb, insensitive, and powerless. ”

“ It is probable that a simple embolus cannot be followed by a gangrenous focus in the lung. This result is recognized frequently when the embolus originates in a purulent deposit, whether it be the consequence of an abscess, of puerperal fever,59 of a compound fracture, etc. The gangrenous cavity finally softens, its contents are expectorated, and the pulmonary tissue becomes indurated and cicatrizes around the excavation. ”

“ When an embolus lodges in an artery and produces complete occlusion, the portion of brain supplied thereby becomes at once entirely anæmic, since the arteries on the surface have so slight anastomoses that they are entirely unable to supply the deficiency, except to a slight extent around the edges of the vascular territory involved. The anæmia, however, does not extend beyond the territory originally affected, and consequently we may have extensive paralysis from embolism without a marked apoplectic attack. In extreme congestion of the brain the reverse may seem to be the case. ”

“ When suppurative hepatitis arises from an embolus, or emboli, the [p. 1006] first step is the change in the appearance of the acini, which are enlarged and grow softer by disintegration of their cells; then at the centre a yellowish spot appears, and is made up of the detritus, granules of fat, and pus. Surrounding such softening portions of the hepatic tissue is a zone of congestion. When the morbid processes are excited by emboli, there will be as many centres of pus-formation as there are particles distributed by the vessels—from two or three to fifty or more. ”

“ Again, the size and seat of the embolus will always have great importance in regard to the prognosis. If the trunk or primary divisions of the pulmonary artery be suddenly and completely obstructed by emboli, sudden death will surely follow. If secondary divisions of the pulmonary artery are filled up, more or less grave symptoms will usually follow. When emboli are carried into the tertiary or still smaller branches of the artery, they may not occasion any appreciable phenomena other than a moderate and passing dyspnoea. ”

“ It is probable that in many cases these arteries are too small to be of great value in re-establishing the circulation in the anterior portion of the brain when it is suddenly interrupted by an embolus. ”

“ A long and narrow embolus might pass through a vessel which would not admit one which was short and thick. A jagged and dense embolus, by repeated blows or prolonged and forcible contact, might cause a weakening or rupture of the wall of a vessel, and thus produce an aneurism. Certain vessels (the terminal arteries of Cohnheim) furnish the sole supply of arterial blood to a district, and when they are obstructed, the results, to be mentioned later, differ widely from those taking place where free vascular anastomoses exist. ”

“ Embolism is a sudden attack which may be as severe at first as even a few minutes afterward. It is also prepared for by disease of other organs, which may or may not have symptoms according to the origin of the embolus. As embolism affects especially those regions where the motor centres are spread out, while hemorrhage attacks more frequently the conductors in their locality of concentration, the paralyses arising from the former affection may be more narrowly limited. ”

“ When a vein is inflamed the blood in it is apt to form a clot, or thrombus, which, if loosened and displaced from its original position, may be carried as an embolus towards the heart and there be arrested ”

“ By the irritative character of the thrombi themselves, they excite inflammatory action in the adjoining tissues; in this way are produced multiple abscesses. Therefore, we find in persons who die under such conditions, abscesses in the brain, heart, lungs, kidneys and intestines; further we may find purulent inflammation and abscesses in the connective tissues.
It is now necessary to explain the nature and composition of both the thrombus and embolus, and how, through their mechanical agency, the process of embalming may become seriously impaired, if not altogether arrested. ”

“ So far as we can tell, the causes leading to endarteritis or atheroma are essentially the same as those which produce the periarteritis described in connection with cerebral hemorrhage, and we may therefore put down old age, alcohol, and strain as among the causes of cerebral embolism. Injuries of the lungs leading to thrombosis of the veins may be considered as possible sources for the formation of an embolus, and we might suppose that phthisis and pneumonia would furnish plugs which would lodge in the brain, though as a matter of fact they seldom do so. ”

“ On several occasions in which blood has been effused freely into the pelvic cavity, either as a consequence of tubal pregnancy, or as a sequel to an operation, such as an abdominal myomectomy, and the blood has been allowed to remain, or it has been inefficiently drained, the patients have died from septic pneumonia.
In cases of septic thrombosis the patients run a definite risk from pulmonary embolism. When the embolus is large the patient sometimes dies in a few minutes (see p. 101) ”

“ At the post-mortem examination the left and right branches of the pulmonary artery contained an embolus. From the surgical point of view there are no reasons why such a bold example should not be repeated with success.
When patients who are profoundly anæmic from menorrhagia due to fibroids undergo hysterectomy, it is a useful measure to give them twenty grains of citrate of sodium twice daily in order to diminish the abnormal tendency of the blood to coagulate in the vessels. Certainly this drug should be administered if there is the least evidence of thrombosis. ”

“ LIII) . In this instance, the thrombus originated in the right iliac veins; and, although no attempt was made to demonstrate the primary vascular lesion, so many similar cases are recorded (7, 82) , and vascular damage is so frequent in this disease, that the hypothesis attributing pulmonary embolus to a thrombus initiated by a phlebitis is strongly supported.
Parenchymatous and skeletal lesions of hemorrhagic type, although variable quantitatively, are frequent and involve the muscles, the parenchymatous organs,—the adrenal especially,—and the mucosa of the alimentary canal. ”

“ The circulation in the muscles is enough for a moderate nutrition but altogether inadequate to sustain active work.
Chronic Embolism of the Internal Iliac Artery. In this case the control of the muscles of the limb may be perfect but there is some indication of paresis of tail, bladder, rectum and anus. Impaction of the rectum is liable to occur. By examination through the rectum the pulsations are felt to be strong in the aorta and external iliac, but imperceptible in the internal iliac blocked by the embolus. ”

“ Prognosis and Treatment.—In the majority of instances, when there is occasioned serious inconvenience, the outcome is not likely to be favorable, according to Möller. Detachment of a portion of the thrombus, according to Hoare, may result in the lodgment of an embolus in the brain or kidneys. The latter authority also states that muscular atrophy may occur owing to lack of blood supply in some of these cases. Möller states that moderate exercise or work stimulates the establishment of collateral circulation. Massage per rectum is condemned as dangerous by Cadiot.
Fracture of the Patella. ”

“ Wilson Fox summed up from the records between 50 and 60 deaths from effusion in the pleural sac. Moreover, many patients have died where the disease was not recognized. The condition of the circulatory apparatus is such that we can readily understand that emboli would form in the heart, in the large blood-vessels, and in the parenchyma of the lung itself. These clots produce grave results. If they form in the pulmonary veins or in the left heart, they determine an embolic obstruction of the central artery, with all its consequences—apoplexy, hemiplegia, etc. ”

“ The primary infection is usually in a wound--for example, a compound fracture--but cases occur in which the point of entrance of the bacteria is not discoverable. The dissemination of the organisms takes place through the medium of infected emboli which form in a thrombosed vein in the vicinity of the original lesion, and, breaking loose, are carried thence in the blood-stream. These emboli lodge in the minute vessels of the lungs, spleen, liver, kidneys, pleura, brain, synovial membranes, or cellular tissue, and the bacteria they contain give rise to secondary foci of suppuration. ”

“ In air-embolism the pulmonary arteries contain a mixture of blood and air looking like a stiff-beaten white of egg of red color. Large emboli of liver-tissue or liver-cells may be found in the pulmonary arteries after traumatic rupture of the liver. Fat-emboli of the smaller arteries can be recognized by the naked-eye. Thrombosis of both pulmonary arteries and veins is very common in chronic valvular lesions, pneumonia, terminal infections, burns of the skin, poisoning with hemolytic agents, etc. ”

“ The very marked symptoms of vascular obstruction—the sero-hæmorrhagic intestinal infarct—in embolism and thrombosis of the mesenteric arteries are easily explained by paralysis of the muscular coat of the intestine, by the absence or paucity of valves in the portal vein, by the readiness with which meteorismus (or flatus) arises, especially in herbivora, and by the loose consistence of the intestinal walls or villi.
13. The occlusion of the intestinal arteries, especially that arising suddenly, always has for its result a partial or complete paralysis of the portion of bowel which they supply. ”

“ Embolism, Thrombosis, Hemorrhage, and Abscess of the Spinal Cord.
Although the spinal cord is a segment of the same central organ as the brain, nourished in a similar way, and subject to the same physiological and pathological laws, lesions of the vascular apparatus, which play so important a part in brain pathology, play a comparatively insignificant one in that of the spinal cord. Embolic, thrombic, and primary hemorrhagic lesions of the cord are so rare that their possible existence has even been denied. ”

“ Sooner or later, in most instances of the severe form of this disease, emboli from the ulcerations in the heart reach the different organs of the body, and of course the symptoms will depend on the place in which the emboli locate. If in the abdomen, there are colicky pains with disturbances, depending on the organs affected; if in the brain, there may be paralysis, more or less complete. In all infaret occurs in one of the organs of the body there must of necessity occur a necrosis of the part and an added focus of infection. ”

“ In the thorax the heart is flabby, pale, and small; clots are found in the right and left side extending into the pulmonary artery and aorta. Sudden death has been attributed to cardiac thrombosis. That coagula [p. 706] do form in the heart during life is shown by the sudden occurrence of cerebral embolism with aphasia.32
32 The writer has seen one case of this kind occurring during the effort at stool in a patient who was very feeble and very anæmic from chronic intestinal inflammation with ulceration. ”

“ Thrombosis and Embolism.
A blood-clot formed within a blood-vessel during life is called a thrombus. The entire process of which the thrombus is the essential element is designated thrombosis.
These terms were introduced by Virchow17 to avoid the confusion which resulted from regarding the process and result as synonymous with inflammation of the vessel. All writers, even at present, do not adhere to this strictness of meaning. For a thrombus of the vulva indicates a clot of extravasated blood within the connective tissue of the labium ”

“ Practically there is no harm done by the injection of air under the skin, yet it elevates the skin at the site of the defect and hinders the surgeon in accomplishing the best results.
These emboli cause a bulging up of the skin for the time being and may occasion more or less pain to the patient, which passes away in ten or twelve hours, leaving the parts as injected except for such reactionary symptoms or edema, already referred to.
10. Paraffin Embolism.—The creation of an embolism is invariably due to an injection of the foreign substance directly into a blood vessel. ”

“ In a great number of cases the thrombus of the worm-aneurism is continued past the mouth of the anterior mesenteric artery, into the lumen of the aorta, and, as such, is the exclusive cause of the embolisms of the pelvic and crural arteries which bring about the intermittent hobblings (the author says “intermitterenden Hinken,” not “Hahnentritten,” the usual equivalent term for stringhalt) . ”

“ If the drop is examined, it is possible by careful focusing, to discover in the spaces between the masses of corpuscles many examples of delicate fibrin net work. The physiological value of the clotting of blood in life is that it stops hemorrhages by closing the openings of the wounded blood vessels, but the clotting of the blood after death, is to the embalmer one of the bugbears, and a real method of preventing it, or of dissolving [67] the clot after it has once formed in the blood vessels is one of those difficult problems which remains as yet unsolved. ”