On the law which regulates the relative magnitude of the areas of the four orifices of the heart / by Herbert Davies.
- Davies, Herbert, 1818-1885.
- Date:
- 1870
Licence: Public Domain Mark
Credit: On the law which regulates the relative magnitude of the areas of the four 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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![fibres pass from the left to the right ventricle and dip in or bend at the track of the anterior coronary artery to become continuous with fibres having a similar direction in the septum”*. 2. In the next place, it must be admitted that equal volumes of blood pass in exactly equal and the same times through any two corresponding orifices of the heart; for it, for example, we could suppose the quantity thrown out through the pulmonic orifice into the lungs to be persistently greater than the amount thrown out in the same time through the aortic opening into the general circulation, it would inevitably follow that over- whelming pulmonary engorgement, cessation of flow from the right heart, and death would rapidly ensue. The alternative supposition of the right %entricle persistently discharging into the lung-capillaries an amount of blood actually less than the quantity as persistently set forth by the left ventricle into the systemic circulation, involves a physical contradiction un- necessary to refute. Whatever, therefore, may be the actual capacities of the ventiieles, or the quantities which under pressure they maybe made to contain, this law must be always paramount to enable the healthy heart to act freely and without the production of a congested or overloaded condition of the pulmonic or systemic circulations ; the quantities of blood entering the ventricles synchronously must be equal, and the quantities leaving them synchronously must also be equal; and to prevent the occurrence or pro- duction of cardiac congestion the quantity of blood received by the ventricles in diastole must equal the quantity expelled by the ventricles in systole, small deviations being allowed within certain limits of health. We shall see the bearing of these latter remarks when we consider the mode in which hearts much diseased in their orifices and valvular apparatus are often enabled to carry on a tolerably unembarrassed circulation, and with but little functional disturbance experienced by the individual so circumstanced. The anatomy of the organ fully corroborates the principle we are seeking to establish ; for we are told that “ the capacities of the ventricles are pro- bably equal ” (Cruveilhier); and again, “there are reasons for believing that during life any difference between the capacities of the ventricles is very trifling, if it exist at all ”f. And lastly, “ the whole, or very nearly the whole of the blood contained in the ventricles is discharged from them at each systole; for the left ven- tricle is frequently found quite empty after death; and if a transverse section be made through the heart in a state of well-marked rigor mortis (which may be considered as representing its ordinary state of complete contraction), the ventricular cavity is found to be completely obliterated ” From these considerations we may, I believe, fairly assume that (]) i Equal times of ventricular contraction, I Equal times of ventricular dilatation, * Pliil. Trans, part .3, 18(i4. t Qunin’s ‘ Anatomy,’ by Dr. Sliarppy, yol. iii. p. 2.’).).](https://iiif.wellcomecollection.org/image/b22454883_0015.jp2/full/800%2C/0/default.jpg)
