Diseases of the heart and circulation in infancy and adolescence / by John M. Keating and William A. Edwards.

  • Keating, John M. (John Marie), 1852-1893.
Date:
1889, ©1887
Catalogue details

Licence: Public Domain Mark

Credit: Diseases of the heart and circulation in infancy and adolescence / by John M. Keating and William A. Edwards. Source: Wellcome Collection.

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    1st Short 2d LoDg Sound. Pause. Sound. Pause complex sound,—the mus- culo-valvular sound; the muscular element being made apparent by the stroke of the heart against the chest-wall and by the audible contraction of the cardiac muscle. It is the long, low, dull boom. The second, or valvular, sound is short, clacking, abrupt, and ringing; it is almost purely valvular, and is due to the sudden closure of the semilunar valves, the aortic and pulmonary. While this is happening the blood is slowly find- ing its way from auricles to ventricles through the opened mitral and tricus- pid valves in order to pro- duce another systolic ac- tion. The aortic and pul- monary arteries at their origin, the chordae tendinese, and the whirl of blood in the ventricles severally as- sist in the- production of the cardiac sounds. Just how much of it they con- tribute is as yet a moot question. The sounds and pauses of the cardiac rhythm will perhaps be made clear by the accompanying diagram- matic representation with which we have been accus-