On the state of the circulation in acute diseases / by A. L. Galabin.

  • Alfred Lewis Galabin
Date:
[cbetween 1800 and 1899?]
Catalogue details

Licence: Public Domain Mark

Credit: On the state of the circulation in acute diseases / by A. L. Galabin. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    5/48 (page 3)
    descending curve, shows a gradually diminishing magnitude as compared with the primary. The primary wave, when separated from the tidal, denotes the steepness of front of the true pulse-wave, and, therefore, by inference, the initial vigour of the heart's contraction. I do not, therefore, greatly object to the term percussion-wave, which has been commonly applied to it, although I believe that no percussion takes place except in the communication of motion from the artery to the sphygmograph, and that what occurs even there is not percussion, in the strict sense of the word. As to the dicrotic wave, I think that the common theory, which attributes it to a recoil produced by the closure of the aortic valves, is only partially true^ and that two causes mainly contribute to its formation. The first of these is a recoil from the aortic valves, as the common theory supposes. I think, however, that, as to the mode of origin of this, sufficient regard has not generally been paid to the effect of the inertia of the fluid. It is evident that all changes of state in the aorta close to the valves will be propagated as waves to the periphery, although these waves may become modified as they proceed. Considering, then, the state of things in the aorta near to the valves at the moment that the ventricle ceases to contract, the blood will for an instant continue to flow away in consequence of its acquired velocity, and, the propelling force behind having ceased, the pressure will fall. As soon as the acquired velocity is checked by the pressure in front there is a slight retrograde motion, which closes the aortic valves, and, being reflected from them, causes a second forward wave of increased pressure and expansion. The preceding retrograde motion and fall of pressure is also as a wave propagated forwards, although the motion of indi- vidual particles is at first backwards, and thus it does not in- volve any reflection from the periphery. As soon as it has pro- ceeded a short distance from the heart it consists no longer of any actual retrograde movement of particles, but only of a dimi- nution of forward velocity. Since, therefore, the fall and subsequent elevation of pressure, which constitutes the first cause of the dicrotic wave, depends on acquired velocity in the fluid, dicrotism is increased if the density of the fluid be increased, or if the tension in the