On the interpretation of cardiographic tracings, and the evidence which they afford as to the causation of the murmurs attendant upon mitral stenosis / by A. L. Galabin, M.D.

  • Galabin, Alfred Lewis, 1843-1913.
Date:
[cbetween 1800 and 1899?]
Catalogue details

Licence: Public Domain Mark

Credit: On the interpretation of cardiographic tracings, and the evidence which they afford as to the causation of the murmurs attendant upon mitral stenosis / by A. L. Galabin, M.D. 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.

    11/64 (page 9)
    It often happens that when the centre of impulse corres- ponds to a rib and not to an intercostal space, or when the heart is covered by emphysematous lung, only a partially or wholly inverted tracing can be obtained at the apex. The mixed tracings are often too complex to interpret (PI. II, fig. 2), but those wholly inverted may be available (PI. I, figs. 10, II, 12, 16), although they rarely show the minor waves so distinctly as those that are positive. Negative tracings are obtained most perfectly when the breath is held in deep inspi- ration, instead of in expiration. To see most clearly their correspondence with positive tracings, they should be turned upside down and read from right to left. If we consider what sort of curve would be produced by the hardening of the ventricle, it is evident that it would rapidly rise to its maximum height, which would be reached almost immediately upon the closure of the auriculo-ventricular valves, and that from the summit there would be a continuous descent during the rest of systole due to the diminution of size of the heart as it contracts. This point may also be tested by direct experiment. The tracing in PI. I, fig. 8, was obtained from the heart of a dog whose thorax had been opened. The spring-pad was placed upon the surface of the right ventricle, near the auriculo-ventricular groove, so that no elevation in the trace could be produced by the locomotion of the heart in the direction of its apex. The spring indented the heart during its relaxation, and its elevation was obviously due to the hardening of the ventricle, and commenced from the moment that contraction was first visible. Fig. 7 was obtained from the same heart when its contractions were becoming slow, short, and imperfect, resembling those which may be supposed to occur in a dilated heart. It had then adopted a peculiar rhythm, so that its motions occurred in pairs, each stronger contraction being followed by one more feeble, as sometimes occurs with the human heart in cases of mitral disease, and especially when that valve is contracted. Looking at fig. 8, it is evident that the systolic portion of the curve has exactly the shape already anticipated on a pinori grounds. Therefore the hardening of the ventricle accounts fully for the main part of the elevation in the curve, and for the first pointed summit d, but not for the elevation