Pathology


Categories: Uncategorized
Sources: Disturbances Of The Heart

The part of the heart most affected is the part which has the most

work to do--the left side of the heart--and of this side the left

ventricle and therefore the mitral and aortic valves; the most

frequent valve to be inflamed and to stiffer permanent disability is

the a mitral valve, the valve which in its inflamed condition is

subjected to the greatest amount of pressure and therefore

irritation. Not infrequently soft systolic murmurs are heard at the

pulmonary and tricuspid valves during acute endocarditis. It is

rare, however, that these valves are so affected during childhood or

adult life as to be permanently disabled.



Whether a diminished alkalinity of the blood in rheumatism has

anything to do with the cause of the frequent complication of

endocarditis has not been determined. Whether the administration of

alkalies to the point of increasing the alkalinity of the blood is

any protection against the complication of endocarditis has also not

been positively demonstrated, although clinically such treatment is

believed by a large number of practitioners to be wise.



A chronic endocarditis with permanent lesions of the valves may

become an acute inflammation with an infectious provocation.



It has been shown that even in a few hours after endocarditis has

started, little vegetations composed of fibrin, with white blood

cells, red blood pigment and platelets, may develop. Practically in

all instances such vegetations develop, and later become more or

less organized into connective tissue. These little vegetations,

generally minute, perhaps not exceeding 4 mm. in height, are

irregular in contour like a wart. Some of these may have small

pedicles, and as such, of course, are more likely to become loosened

and fly off into the blood stream. It is of interest to note that

these little vegetations are more likely to be on the left side of

the heart than the right; on the valves than any other part, and on

the mitral valve than on the aortic. The consequence is a more

frequent permanent disability of the valves of the left side of the

heart, and of these more frequently the mitral. Although these

little vegetations and excrescences sooner or later become mostly

connective tissue, still fibrin and white blood cells may form thin

layers over them, more or less permanent. In this fibrin are

frequently found bacteria, even when there has been no recent acute

inflammation. The deeper layers of the endocardium during acute

inflammation may become infiltrated with young cells, with resultant

softening and destruction of the intercellular substance. This

softening and some swelling of the lower layers of the endocardium

allow the pushing up of these extravasated blood cells which, being

covered with fibrin, makes the little vegetations above described;

and as just stated, the fibrin may form a more or less permanent

cap. If this cap is disintegrated or lost and the cells under it

washed away in the blood stream, ulceration takes place, which may

be more or less serious, even to the perforation of a valve or

actual erosion of one of its cusps, and the parts of the valves most

seriously affected are the parts which strike against each other on

closure; as previously stated, the parts subjected to the greatest

strain and the greatest amount of friction during the inflammation

are the parts most seriously affected afterward.



If a perforation has occurred, it may make a permanent leak. If an

erosion of the edge of the valve has occurred, it may make permanent

insufficient closure. If the valve has become thickened and

stiffened during the cicatricial healing, it may not only be

incompetent, but may not open perfectly, and a narrowed orifice may

be the consequence. During the healing of these granulating ulcers

there may be thickening of the part or shrinking of the tissue, and

the valve may become shortened by adhesion to the wall, or the cusps

of the valve may adhere together so that the valve becomes

permanently unable to open properly or to close properly, or to do

either.



Not infrequently and probably more frequently than we recognize,

recovery without any of the pathologic lesions just described

follows mild endocarditis. The occurrence of simple endocarditis is

undoubtedly frequent during acute disease, and is unrecognized

because there are no lesions of the heart at the time or

subsequently; but valvular lesions only too frequently follow the

endocarditis which occurs with rheumatism. Occasionally the

ulcerations become serious, and ulcerative endocarditis or malignant

endocarditis develops on the mild inflammation. In this form the

little vegetations are liable to become loosened, fly off into the

blood stream, and cause emboli in different parts of the body.



Recently Fraenkel [Footnote: Fraenkel: Beitr. z. path. Anat. u. z.

allg. Path., 1912, iii, 597.] concluded that the microscopic nodules

which occur in endocarditis in the myocardium, and which consist of

the several varieties of white blood corpuscles first referred to by

Aschoff in 1904, are characteristic only of acute rheumatism.

Fraenkel found these nodules in the myocardium in a case of chorea,

showing the close relationship between it and rheumatism.



While repeated careful examination of the heart during acute

infections will generally show signs of endocarditis if it is

present, even if there are no subjective symptoms, the disease may

be so insidious as not to be noted until a valvular lesion occurs.

Often, however, during the course of the disease, especially in

rheumatism, there is a slight increase in fever and there is a

discomfort complained of in the region of the heart, frequently

accompanied by slight dyspnea. Real pain is seldom present unless

the pericardium is affected. If the myocardium is much inflamed at

the same time, the heart becomes more rapid and the blood tension

lowered, and the apex beat diminished in intensity and perhaps not

palpable. If there is pain, with or without pericarditis, it is

often referred to the epigastrium, especially in children. The

patient is often nervous, restless and sleepless. In simple

endocarditis emboli rarely occur. If they do, of course the signs

will be in the part in which the infarct occurs. Besides the

diminished intensity of the apex beat and its greater diffusion, the

valve sounds may be muffled, and sooner or later there may be

systolic murmurs over the different orifices. Of course systolic

murmurs may be due to a disturbed condition of the blood, but if

they occur with the above-mentioned symptoms and signs, endocarditis

should be diagnosed. If the heart becomes seriously weak and the

patient suffers much dyspnea, myocarditis should be known to be

present with the endocarditis. If there is a diastolic murmur, there

can be no question of serious endocarditis having occurred.

Unexplainable palpation during acute illness liar been thought to be

a distinct symptom of endocarditis.





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