1. Tuberculosis

This is rare as a lesion of the heart itself, but frequent and important in the pericardium. Tuberculosis of the heart is an occasional accompaniment of acute general tuberculosis, and is not infrequent in children. There are the usual nodules in the muscular substance and in the endocardium. In some cases a more definite tubercular endocarditis has been observed with the usual features of an acute endocarditis.

Tubercular pericarditis arises by infection from some part in the neighbourhood of the heart. This is mostly the mediastinal glands (Weigert), but may be the pleura. A tuberculosis of the mediastinal glands may slumber on for many years, and an accidental extension to the parietal pericardium may result in the launching of the infective agent into the sac. The bacillus is dispersed throughout the sac, where it multiplies and produces its toxine.

At the outset there is usually an acute inflammation with the features of acute pericarditis described above, but there is not usually much serous exudation. A fibrinous deposit is formed beneath which small miliary nodules are visible. As the disease becomes chronic there is great new-formation of connective tissue and of tubercles. The process occurs in both the visceral and parietal layers of the pericardium, and the two layers are liable to coalesce so that adherent pericardium results. The condition, however, differs greatly from ordinary adhesion of the pericardium in respect that there is very great thickening. In the case from which Fig. 233 is taken the pericardium had a thickness of from 15 to 2.5 cm. The heart is thus encased in a dense thick capsule which must have greatly impeded its movements.

Fig. 233. - Tubercular pericarditis. The ventricles are shown in section. There is very great thickening of the pericardium, and the two layers have coalesced.

Fig. 234. - Gutnmata in wall of left ventricle. A large portion of the wall is occupied by gummatous tissue. (From a coloured drawing by Dr. Alex. Macphail).

In the thick adherent pericardium it is usually possible to distinguish two layers of tubercles, one belonging to the visceral, and one to the parietal layer of the pericardium. Under the microscope there will be found large masses having the indefinite characters of caseous necrosis with occasional fresh tubercles, in the midst of tissue which presents in some parts evidences of recent inflammation and in others merely dense connective tissue.

2. Syphilis

This occurs in the heart chiefly in the form of gum-mata which have their seat in the muscular substance in any region. The gumma, which may attain considerable dimensions (see Fig. 234) is a dense tough body of somewhat indefinite structure, and it is-surrounded in the usual way by cicatricial connective tissue which replaces the muscular substance, producing an interstitial myocarditis. The endocardium and pericardium are thickened, and the latter may show adhesions. Besides the gummata a limited fibrous induration may have a syphilitic origin. A syphilitic affection of the valves has been described, but is very rare.

Actinomycosis and Hodgkin's disease may extend from the mediastinum and lungs to the pericardium and heart, but are not independent diseases.

Literature

Tuberculosis. - Tripier, Arch, de med. exper., 1890; . Weigert,. Virch. Arch., vol. lxxv., 1879; Pollak, Zeitsch. f. klin. Med., xxi., 1892 (literature). Syphilis. - Virchow, Geschwiilste ii., 441, 1865; Lancereaux, Traite de la Syph. 1873; Lang, Path, und Ther. der Syph., 1896, Syph. des Herzens, 1889; Volmar, Ueber Gummata des Herz, 1893; Mracek, Arch. f. Dermat. Suppl. 1893 (with literature).