The murmurs of mitral disease / by Edward Mansfield Brockbank.

  • Edward Mansfield Brockbank
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: The murmurs of mitral disease / by Edward Mansfield Brockbank. Source: Wellcome Collection.

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    A theory which explains the prevention of regurgitation at the onset of ventricular systole in mitral stenosis must hold good, not only when the auricle is hypertrophied or even of normal thick- ness, but also when the auricular wall, as so often is the case, is atrophied or abnormally thin; and the above theory, to my mind, entirely fails in this. But although the question of the rhythm of the so-called presystolic murmur has been so much discussed in the past fifty years, as far as I can find, no explanation of the causation of the very important characteristic of ascending pitch, which the murmur always possesses, was offered until I published a paper on this subject in June 1897.1 The method of causation of the murmur in question is, in the present writer's opinion, all-important, for once the means by which the murmur obtains its peculiar characteristics be recog- nised, the simpler becomes the attempt to define the true rhythm of the murmur. This theory is dealt with fully in the next chapter. Cowan, in 1898,2 propounded a theory which agrees with my contention, that the ascending pitch characteristic of the crescendo murmur is due to blood being forced through the mitral valve whilst its orifice is being rapidly diminished in lumen, and also with the view held by others as well as by myself, that the terminal abrupt sound is caused by the impact of the hard roughened edges of the diseased mitral valve. He believes, however, that the crescendo murmur of mitral stenosis is caused during ventricular systole by blood flowing from the auricle through the mitral valve into the ventricle whilst changes in the tension of the valves and alterations in the lumen of the orifice are taking place, the result of contraction of the ventricle as a whole, and of the musculi papillares in particular. Cowan is of the opinion that at the commencement of ventri- cular systole the pressure of the blood in the ventricle will be slight compared with that in the auricle, and until the ventricular pressure rises above the auricular pressure, as the result of the ventricular systole, the valves will not be closed, and blood will flow into the ventricle from the auricle. The objections to such a theory are practically the same as those offered to Samways' views on the previous page. 1 Med,. C'hron., Manchester, June 1897.
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