On the four chief orifices of the heart / by Herbert Davies.

  • Davies, Herbert, 1818-1885.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: On the four chief orifices of the heart / by Herbert Davies. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    of the blood, by filling the sacculi on the under surface, unfurls, flattens out, and enlarges the valve, so as to maintain it almost of full size to the end of systole.” If, then, it be true that all the chief orifices of the heart are circular in form when in action, and that their respective areas are constant during systole and diastole, certain objections which have been raised to the truth of the statements made in my former paper are removed, and the correctness of the formula which I have discovered, viz.:— Area of Tricuspid _ Area of Pulmonic Area of Mitral ~ ArcaTof Aortic becomes more fully established. And if it be also true as it undoubtedly is—that equal volumes of blood must pass synchronously through the pulmonic and aortic openings, and that the two ventricles exert very unequal pressures upon these equal volumes of blood in systole, it must follow, if the velocities are unequal, that equal times of efflux can be only obtained by the areas of the aortic and pulmonic orifices being inversely as the velocities of the streams which traverse them. During the period of each systole, the left ventricle has not only to sustain and neutralise the pressure of the aortic column, but also to send forth nearly five cubic inches of blood into that vessel. The latter is by far the smallest portion of its task, as shown in an able paper written by Di. Andrew Buchanan, of the University of Glasgow upon the “Effective Force of the Heart;” but the principle’ the formula, for the truth of which I am contending (the result of the correlation of the forces of the two hearts), does not involve the objects for which the forces of the two ventricles are put forth. It is sufficient to know that the velocities are unequal, that they result from the operation of unequal forces m equal times upon equal masses of blood, to be convinced t at the areas of the openings must be inversely as the velo-