Heart studies, chiefly clinical. 1, The pulse-sensations : a study in tactile sphygmology / by Wm. Ewart.

  • Ewart, William, 1848-1929.
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Heart studies, chiefly clinical. 1, The pulse-sensations : a study in tactile sphygmology / by Wm. Ewart. Source: Wellcome Collection.

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    These are also the conditions realised, though im- perfectly, by the button of the sphygmograph. Spontaneous Pulsation Suppressed in Rigid Tubes. In atheromatous or calcified arteries, the conditions are different: there may be considerable volume of the artery, and yet feeble pulse, whilst arteries of more moderate size may yield extensive pulsation. This difference is capable of being explained. In rigid tubes, a glass tube for instance, no pulsation could be seen, although the pumping force might be equal to that of the heart. The rhythmic expansion of the arterial wall is the result and the expression of the elasticity of the tube ; and we may speak of this visible expansion as the objective pulsa- tion referred to in previous remarks. Conversely, a membranous tube, originally elastic, if sufficiently thickened by overgrowth, or if suffi- ciently stretched by its own contents, may lose so much of its elasticity as to pulsate feebly or not at all. This same tube will yield a throbbing if any part of its outer surface be dimpled in by the pressure of a rod, with just enough force to overcome the pressure stretching its walls. The rod will then perform movements analogous to those obtained when the finger is applied to an elastic artery. In this case the pulsation is not spontaneous. It depends upon interference on the part of the observer, and in that sense may be regarded as manufactured. This experiment lies at the root of Sir William Broadbent's explanation. Some arteries are so tense, that their pulse is only obtained by the appli- cation of full pressure. The object of this pressure