A system of practical medicine. By American authors. Vol. 3

by Unknown

CLINICAL HISTORY.—In by far the majority of cases there is an evident source for an embolus. Pain in the abdomen is the first symptom, and usually remains one of the most prominent throughout. At first it may be a dull aching just below the borders of the ribs, but soon there is superadded paroxysmal pain resembling colic, and which may at times even be relieved by pressure. The occurrence of this colic in cases where embolism might happen ought to put the physician on his guard for other symptoms; for, though insufficient in itself to establish a diagnosis of embolism, the presence of a colic resisting treatment in the course of cardiac disease justifies the suspicion that this may be the case. The pain is usually located near or above the umbilicus.

Intestinal hemorrhage occurs in nearly every case; death may take place before any change in color of the stools is observed or any blood appears at the anus, but on post-mortem examination blood is found in the intestine. The cause of this hemorrhage is the infarction of the intestine analogous to that which takes place in other organs supplied by end arteries, the superior mesenteric having been proved experimentally to be functionally such an artery, owing to its great length, the extent of tissue supplied by it, and the comparative smallness of the vessels with which it anastomoses on the borders of its territory. The collateral circulation is thus so long in being established that ample time is allowed for those disturbances of nutrition in the walls of the vessel which render them permeable and allow the blood to escape. In view of the hemorrhage certain other symptoms are readily accounted for, as, for example, pallor of the face and surface of the body, the considerable and rapid fall of the temperature, syncope, hæmatemesis, diarrhoea, and melæna. These two latter symptoms are important though inconstant. There is reason to believe that the first effect of the embolism is to paralyze the bowel and prevent peristaltic action. Diarrhoea is of frequent occurrence, and may be profuse, the stools remaining of their natural color; or fresh blood may be passed at first from the rectum, followed by the continuous passage of tar-like masses; or the stools may be of pulpy consistence, mixed with blood, or consisting of tarry blood. Lastly, profuse hemorrhage may take place in which the stools resemble tar-water. The character of the blood does not give any kind of clue to the locality of the lesion.

Vomiting is a frequent symptom, and may consist of altered blood of variable consistency. A fall in temperature can often be determined by the thermometer, especially after severe hemorrhage. Not rarely the temperature is normal or may be even increased, especially if secondary inflammation has set in.

Tension and tympanitic swelling of the abdomen may occur or fluid may be detected late in the case, these being evidence of peritonitis.

PATHOLOGY.—Before proceeding to consider the pathological changes occurring in embolism, a few words on the blood-supply of the intestine might perhaps render what follows clearer. The superior mesenteric artery supplies the whole of the small intestine except the first part of the duodenum; it also supplies the cæcum and the ascending and transverse colon. The inferior mesenteric supplies the descending and sigmoid flexure of the colon and the greater part of the rectum. The anastomoses are as follows: The pancreatico-duodenalis, a very small artery and a branch of the hepatic, anastomoses with the first branch of the superior mesenteric, also a very small artery and given off under cover of the pancreas. The middle colic artery anastomoses with a branch of the inferior mesenteric. Both these arteries are given off from the main trunks of the arteries.

The experiments of Litten in 1875 show that the superior mesenteric artery, though not so anatomically, is functionally a terminal artery, the anastomosis not being developed with sufficient rapidity in case of extensive embolism to ensure the integrity of the circulation.

1. The result of sudden total closure by embolism of the trunk of this artery, therefore, is precisely like that of ligature of this artery in animals, and is first to produce sudden abdominal pain, attacks of colic, vomiting, uncontrollable intestinal hemorrhage, death. The intestine from the lower transverse portion of the duodenum to the middle of the transverse colon is found to be suffused, brown-red, blackish, or grayish. All the layers are swollen; innumerable capillary extravasations of small and great extent are seen, with venous hyperæmia and oedematous infiltration. In other words, there occurs necrosis with oedema and hemorrhage in all those portions of the intestines which are supplied by this artery.

2. Closure of large branches by embolism gives rise to infarction of the portion of intestine concerned, followed by death. The symptoms differ only in intensity, if at all, from the preceding. A case has been seen where there was every reason to believe that embolism had occurred, and yet the patient recovered. (The patient, suffering from acute rheumatism complicated with peri- and endocarditis, suddenly developed profuse intestinal hemorrhage of tar-like color, which was repeated twice. Colic pains, tympanites, depression of the temperature of the body, followed. At the same time symptoms of embolism of various other arteries were present. Recovery took place after eight weeks.) This result of course depended on the subsequent perfection of the collateral circulation.

3. Closure of the smallest branches may produce the same kind of symptoms as the above, though less in degree. Limited portions of intestine have been found to be in a gangrenous condition from embolism of very minute branches, more especially when the embolus extended well into the artery. In place of gangrene of the intestine ulcers of the mucous membrane have been seen independent of typhoid fever or tuberculosis. Considerable stenosis has followed such ulcers.

The affected portion of intestine in embolism is found to contain a variable amount of blood mixed with the other contents of the gut. Peritonitis, dry and limited or general and accompanied by effusion, is the rule. The mesenteric glands are found enlarged and succulent, with perhaps here and there necrosed spots. Thrombosis of the corresponding veins is not uncommon. Large collections of blood under the peritoneum and in the mesentery have been observed. The color of the mucous membrane has been slaty, and a diphtheritic appearance has been observed.