DISEASES or TnE ARTERIES. The diseased conditions affecting' arteries consist of (1) de generation of the arterial walls (of either fatty, calcareous, or hyaline variety) ; (2) arterio sclerosis: and (3) aneurism. Fatty degeneration of the intima (or inner coat of an artery) is very common. it occurs as yellowish spots in the aorta and larger vessels. Calcareous degenera tion succeeds the fatty change, and occurs as flakes or plates of chalky deposit in the intima. It is the terminal stage of arterio-selerosis. Hyaline degeneration is a change usually found at the beginning of arteriosclerosis. It oc curs as a smooth. homogeneous substance re placing the tonica intima, generally distributed throughout the smaller arteries and capillaries, especially in the kidney. The substance which replaces the normal tissue of the arterial coat is called athcroma (from Greek meal), whether hyaline, fatty, or calcareous: it consists of a pulpy or hardened mass of cholestrine, oil, albuminous and chalky material. In sonic arte ries. such as those over the temples and at the wrists, chalky deposits or atheromatous thicken ing may be felt easily. Atheromatous deposit is at first attended with a narrowing of the calibre of the vessel. varying with the thickness of the deposit, and most marked at the points of bifur cation. Smaller arteries may be obliterated, while the larger arteries may be very much contracted. A later consequence is dilatation of the vessel. The power of the outer coats being insufficient to compress the deposit and to close in upon the blood, with which each contraction of the left ventricle of the heart distends them, they remain wide and distended during the relaxation of the ventricle. and the artery thus slowly expands; the enlargement being most marked at parts where there is most obstruction to the blood-current—as, for exam ple, in curved arteries. These dilatations are apt
to terminate in regular aneurism. The arteries sometimes become abnormally lengthened, and consequently become not only dilated, hut also tortuous. Another condition involving much danger is this: an ossified artery loses the smoothness which the interior of the vessel ought to present. and from the displacement or crack ing of a bony plate, there may be sharp, rough projections exposed. to which the fibrin of the circulating blood may adhere. These little clots, becoming detached, may be carried with the blood till they become arrested. and plug up an artery. thus presenting cases of embolism or thrombosis (q.v.). A blow may crush a diseased artery, when a healthy elastic vessel might have eseaped injury. A ligature applied to any ossi fied artery is very apt to cause it to break, and the difficulty of securing such vessels is often very great. It is to this form of disease that most of the failures of operations for aneurism are clue. The heart's action in pumping blood through stiff, unyielding arteries whose calibre is diminished causes a permanent rise in the blood pressure. resulting in hypertrophy of the heart, disease of the kidneys, cerebral hemor rhage, aneurism. gangrene or sclerosis of the coro nary arteries. The treatment of disease of the arteries consists in removing the cause when pos sible. maintaining a quiet. well-regulated life, and the adherence to hygienic rules. A rteritis. or inflammation of the arteries, is no longer recog nized by physicians as a specific general disease.
See ARTERIO-SCLEROSIS; HEART; KIDNEYS; APO