Heart-beat and pulse-wave / by C.S. Roy and J.G. Adami.

  • Charles Smart Roy
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Heart-beat and pulse-wave / by C.S. Roy and J.G. Adami. 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.

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    ventricular wall, to distinguish it from that obtained from a part lying between two points on any line running round the ventricles, parallel to the auriculo-ventricular sulcus, which may similarly be termed the transverse ventricular curve. The curves (A, B, C) shown in Fig. 2 are examples of tracings registering the contraction between two points in the middle third of a line joining the base and apex of the left ventricle at some distance from the ventricular septum. The illustration shows three different tracings, in all of which a rise of the record- ing lever corresponds to contraction of the ventricle wall, and a descent to expansion. The contraction begins, then, in each at a. It can be seen that the heart-wall contracts at first rapidly, until the shortening is suddenly arrested at the point b, the height of which on the ascending line varies under different conditions. In curve A (Fig. 2), it is low down, near the com- mencement of the ascent; in curve B it is about half-way up; while in curve C it is near the top. This arrest of the contrac- tion is often followed by a certain degree of expansion, producing a more or less well-marked notch at c. On the other hand, it may (as in Fig. 4, A) be followed by a simple cessation of the contraction, or even by mere slowing, though this, according to our experience, is unusual. After the notch at c, the contraction continues, but is more slow than before. What is the cause of this interruption of the shortening ? We at first thought that it must be due to the tightening of the auriculo-ventricular valves as a result of the rise of the intra-ventricular pressure, produced by the contraction of the heart-wall. That it results from something more than this will be seen when we come to compare the curve of contraction of the musmli papillares with that of the heart-wall itself. We need only remark here that the time between the com- mencement of t he contraction of the heart-wall and this break in the shortening varies under varying conditions, all of which how- ever affect the amount of blood contained within the ventricle at the commencement of systole. The greater the expansion of the heart in diastole, the sooner does this break m the ascending line of the contraction curve follow its commencement, and viceversd. The part of the curve from c to d shows that the heart contracts more slowlv at that part than it did at the beginning of systole. As