Bacteriologically, it should be mentioned that a large number of different microbes have been found in verrucose ancl ulcerative endocar ditis, staphylococci, streptococci, typhoid bacilli, pneurnococci, bacillus pyogenes fcetidits, gonococci, etc. The occurrence of endocarditis depends, according to Frankel and Sanger, upon the blood in the left side of the heart containing more oxygen, which better supplies the oxygen needed by the above-mentioned micro-organisms than does the venous blood of the right side of the heart.
Normally small nodules are frequently found on the valves of the heart, in newborn and young children, during the first year of life, which are usually situated near the free edges of the valves and must be noted here only because they have for some time been mistaken for endocarditis excrescences and because Bouchut. Labadie and Lagrave, who found them in children dead from diptheria, considered them as diphtheritic endocarditis. These conditions, wholly without clinical significance, are to be differentiated anatomically from the round nod ules of .11bini, as big as the head of a pin, seated at the free edge of the venous valves, 20 to 30 in number, and from the peculiar valvular luernatomata which are, according to Haushalter and Thiry, small spherical tumors, dark violet in color, varying front the head of a pin to a grain of rice in size, located some distance back from the free edge of the valve, from 3 to 10 in number.
(b) SPECIAL PATHOLOGY ()F ENDOCARDITIS Clinically acute and chronic endocarditis of children are to be differentiated, the acute form being subdivided into a benign and malignant endocarditis. But acute malignant endocarditis is a great rarity in childhood.
1. Acute Endocarditis in Children Symptorns.—The most important and in many cases the only clin ical symptom is a systolic murmur at the apex, corresponding to the mitral valve, with but slight transmission to the rest of the precordial region at first. As valvular endocarditis in childhood affects the raitral valve almost exclusively, the localization of the murmur is easily under stood. The especial anatomical relation of endocarditis in children to the aortic tip of the mitral valve depends upon the exceptionally great tension of this part of the valve, when the ventricles contract with systole. Murmurs localized at the aortic ostium are very rare in child
hood. Among 33 cases of endocarditis observed by Hochsinger the aortic valves were affected only in four.
Goodardt found among 256 cardiac affections of childhood Affections of the mitral valves in 142, Affections of the aortic valves in 11, Affections of the aortic and mitral valves in 22, and a doubtful diagnosis in 56.
The production of the murmurs in acute endocarditis in childhood may be due to roughness, papillary excrescences, or diminished tension of the valves, chordre tendinete and papillary muscles, from inflammatory changes. The pos.sibility of a relative inability of the mitral valves to close 111 acute parietal endocarditis is not to be denied, although the extraordinarily resistent heart in childhood possesses no especial ten dency toward the rapid development of dilatation. The production of the murmur in valvular endocarditis in children is preceded in most cases by a weakening, impurity or dull quality of the first sound of the heart; Potain even considers this sound anomaly the essential auscul tatory phenomena of mitral endocarditis of childhood; and explains the murmurs which may appear later as extracardial cardiopulmonary mur murs (see p. 456), a point of view which is incompatible with the great constancy of this murmur, with its continuation during respiratory pauses and during expiration, and with its accentuation during crying, as has been observed by Hochsinger repeatedly.
Although, acoustically, as a rule, the murmurs of endocarditis childhood represent a low- blowing or whistling sound joined to the first heart sound, musical murmurs which may completely conceal the first sound of the heart have been observed, even when the endocarditis has lasted only a short time. Sometimes a rnitral murmur witich has ap peared rapidly is heard more loudly in children ill the third intercostal space on the left side than at the apex, if as the result of sudden inability of the mitral valve to close, the murmur becomes accentuated because of the backward movement of blood toward the left auricle. The mur mur of acute rnitral enclocarditis of children is only transmitted imper ceptibly or not at all to the aortic and tricuspid ostia.