6 Path. Anat., vol. iv. p. 59.
Wilson Fox affirms that he has found alveolar thickening in considerable tracts in this affection, with a distinct increase of fibrous tissue in the walls of the alveoli; but this change, he goes on to say, is not uniformly present, and in some places the alveoli are found filled with epithelial products like those of catarrhal pneumonia.
The true explanation of the condition is probably this: that, beginning as a passive congestion, such as might be expected to result from the mitral disease with which it is almost constantly associated, the affection afterward assumes an inflammatory condition of a low type with epithelial proliferation, and in some cases with thickening of the alveolar walls and the interlobular connective tissue. Passive hyperæmia is, however, always the basis of the disease. The brownish spots visible in a section are caused by the leakage of blood from the congested capillaries into the alveoli or interstitial tissue without the occurrence of any large extravasation. The blood thus exuded undergoes pigmentary change, with the production of hæmatoidin, the shades of color varying accordingly as the exudation has been recent or of longer duration.
The failure of the lungs to collapse is due to the encroachment of the dilated capillaries on the air-cells, and perhaps to the thickening of the cell-walls and the partial occupation of the cells themselves by epithelial products.
SYMPTOMS.—The general symptoms and the physical signs of this affection are of the same character as those that occur in other forms of pulmonary congestion. Dyspnoea is felt, especially on making exertion; and this may be attributable in part to the associated cardiac disease as well as to the condition of the lungs. Loss of resonance on percussion and feebleness of respiratory murmur are observable; and when the condensation is great bronchial breathing may be heard.
DIAGNOSIS.—It is evident that there is nothing in these signs distinctive of this particular form of congestion, which is, in fact, not diagnosticable with absolute certainty during life. The probability of its existence may, however, be inferred if along with the above symptoms and signs a presystolic or regurgitant mitral murmur is heard, showing constriction or incompetency of the mitral valve.
PROGNOSIS.—The prognosis of this affection is of course always unfavorable, because the condition depends upon mechanical disease of the heart of an incurable nature. Temporary improvement may, however, sometimes take place under proper treatment.
TREATMENT.—Such treatment must be used as serves to support the weakened heart and hold in check the tendency to dilatation. With this view digitalis or convallaria may be employed, with tonics and alcoholic or ammoniacal stimulants as occasion may require. Counter-irritation over the lungs may be used and expectorants may be given. If dyspnoea be urgent, the preparations of ether, such as Hoffman's anodyne, or the carbonate of ammonia, may be administered.