. Heart disease, with special reference to prognosis and treatment. c mitral murmur, strictly speaking. These varietiesof murmur may be represented diagrammatically as shownin Fig. 11. The disappearance of the second sound at the left of theapex, which, with the short, sharp character of the firstsound, marks the second stage of mitral stenosis, is probablyexplained by the following considerations. In the normal o i94 HEART DISEASE. heart, a second sound is always audible at and to the leftof the apex; and repeated careful examinations have con-vinced me that it is the aortic second sound whic
. Heart disease, with special reference to prognosis and treatment. c mitral murmur, strictly speaking. These varietiesof murmur may be represented diagrammatically as shownin Fig. 11. The disappearance of the second sound at the left of theapex, which, with the short, sharp character of the firstsound, marks the second stage of mitral stenosis, is probablyexplained by the following considerations. In the normal o i94 HEART DISEASE. heart, a second sound is always audible at and to the leftof the apex; and repeated careful examinations have con-vinced me that it is the aortic second sound which is hereheard, and not the pulmonic, even when this is accentuatedand unduly loud. In mitral stenosis, there are two influencestending to prevent the aortic second sound from reachingthe surface of the chest. First, the left ventricle, notundergoing dilatation and hypertrophy, while the rightenlarges greatly, is overlapped by the latter, which usurpsthe position of the apex, and thus the left ventricle cannotconduct the aortic sound to the chest wall. Again, the. FIG. 11.—1. PRESYSTOLIC MURMUR CORRESPONDING WITH AURICULAR MURMUR OCCUPYING WHOLE DIASTOLIC INTERVAL. 3. MURMUR DIVIDEDINTO DIASTOLIC AND PRESYSTOLIC PORTIONS. aortic second sound will be weak, because the diminishedamount of blood entering the ventricle, in consequence ofthe narrowed mitral orifice, will not distend the aorta, andwill, therefore, fail to produce a powerful recoil such as isnecessary for the production of a loud second sound. The modification of the first sound in mitral stenosis isremarkable, and in searching for an explanation of this, oneis struck by the analogy of the sharp, sudden, and tappingcharacter of the apex beat to the shortness and sharpness ofthe first sound, which would seem to imply that somecommon cause has been instrumental in the production ofthese peculiarities in both instances. If this be the case, MITRAL STENOSIS. 195 it is clear that the ventricular Avail must be
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