Acute Endocarditis is a secondary condition occurring in the course of an infectious disease as a result of the action of bacteria. It is characterized by the formation of cauliflower growths upon the valves or by ulceration of the leaflets.

It is found particularly in acute articular rheumatism, chorea, in pneumonia, scarlet fever, puerperal sepsis, and gonorrhea. The organisms most commonly found have been the staphylococcus, streptococcus, and diplococcus pneumoniae, also the gonococcus. In many cases the bacteria probably gain entrance through the tonsils.

The most common seats are the mitral valve, then the aortic and pulmonary valves. In fetal endocarditis the right side of the heart is more frequently involved. Instead of the edge the lesion first occurs on the line of closure. The endocardium becomes opaque and small, irregular nodules appear {verrucous endocarditis). These elevations consist of layers of fibrin, beneath which is the endocardium, showing desquamation of the endothelium with also round-cell infiltration and proliferation of the fixed connective-tissue cells. In the masses of fibrin will be found blood plates, leukocytes, and frequently bacteria.

The process may terminate by a degeneration of the vegetations with the formation of scar tissue and subsequent thickening and contraction. There may also be marked calcareous infiltration.

If the condition continues there may be destruction of the valve, ulcerative endocarditis. In this there is a superficial necrosis of the valve with a deposit of fibrin upon the ulcerated surface. As the lesion progresses the leaflet may become weakened and distended by the blood-pressure, forming an aneurysm of the valve. Perforation may occur and portions of the leaflet, or of the fibrin mass, may be set free in the blood as emboli. These generally contain bacteria, and, lodging in the brain, kidney, and spleen, will give rise to metastatic abscesses.

Fig. 133. - Chronic Verrucous Endocarditis of the Aortic Valves, showing the Warty Projections from Their Edges. The Valves are at the Same Time Thickened and Stiffened by Sclerotic Changes (McFarland).

Either of these two varieties may terminate in the chronic form.

In chronic or sclerotic endocarditis there is an overgrowth of fibrous tissue, usually with calcification, causing a distortion of the valves. The leaflets become thickened, less elastic, rigid and hard, and frequently shortened. As a result the lumen of the orifice may be decreased and give rise to obstruction to the flow of blood (stenosis). On account of the lack of elasticity the valves are no longer able to completely close the orifice, so there is a backflow of blood (regurgitation).

There is also frequently present a shortening and thickening of the chordae tendineae, which on account of preventing the valves from closing gives rise to regurgitation.

This form of endocarditis may be a sequel to the acute vari eties, or it may gradually develop independently of such conditions, as in gout, chronic rheumatism, alcoholism, and syphilis.

There may also be bits of tissue or fibrin broken off, with resulting embolism.

As a result of the disturbances of the circulation which call for increased effort, there is hypertrophy of the heart, with subsequent dilatation.