Clinical electrocardiography / by Sir Thomas Lewis.

  • Thomas Lewis
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: Clinical electrocardiography / by Sir Thomas Lewis. Source: Wellcome Collection.

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    the time-relations of contraction in upper and lower chambers of any given heart. In the mammalian electrocardiograms there is no evidence of a sinus contraction such as is present in the amphibia and reptilia (see Fig. 1 lc^). Fig. 9. A diagram illustrating the simple theory of electric curves. It represents a strip of somatic muscle connected to the galvanometer and stimulated to contract at one or other end. The deflections, which arc shown to the right, vary in direction according to the point at which the contraction originates and with the relation of muscle to electrodes. Supposing that we take a simple strip of muscle, the fibres of which are parallel, and connect its two ends, which we will term proximal (p) and distal (d), to the galvanometer. If this strip is stimulated by a single induction shock, say at its proximal end (Fig. fh4), then a wave of contraction flows from p to d. When the contraction begins at p, the muscle at this end becomes active, it also becomes relatively negative to d, as shown by the swing of the galvanometric recorder ; the swing is in a definite and known direction, it is the same as that given when p is replaced by the zinc terminal of a