Licence: Public Domain Mark
Credit: Heart / by John Reid. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![the dull sound to the contraction of the left ventricle, and the clear sound to the contraction of the right ventricle. Dr. David Williams, while he believes that the first sound depends upon the rush of blood into the large arteries during the systole of the ventricles, attributes the second sound to the musculi papillares, which he considers as forming part of the val- vular apparatus, causing the valves to strike against the walls of the ventricles. Tiiese mus- culi papillares do not, in his opinion, contract during the systole of the ventricles, but imme- diately afterwards, for the purpose of throwing open the auriculo-ventricular valves. In a former part of this article several circum- stances are stated adverse to this o]Dinion. We shall now proceed to the explanation of the cause of these sounds given by those who maintain the views of the rhythm of the heart which we have here adopted, as resting upon the concurrent testimony of numerous accurate observers. These may be divided into those who attribute both sounds to causes intrinsic to the organ, or, in other words, to circumstances occurring within the organ itself, and into those who place them external to the organ, and depending upon extraneous objects. The only supporters of the latter opinion are Magendie and his followers. Magendie maintains that in contracting,and for causes long since known, the ventricles throw the apex of the heart against the left lateral part of the thorax, and thus produce the first sound, i. e., the dull sound. In dilating, in a great measure under the influence of the rapid influx of the blood, the heart gives a shock to the anterior paries on the right of the thorax, and thus produces the second sound, the clear sound. In proof of this, he states that on removing the sternum of a swan (an animal selected expressly for the experiment, as it interfered less with the natural action of the heart than in the Mam- malia), he found that the movements of the heart produced no sound, while, on replacing the sternum, and allowing the heart to impinge upon its posterior surface as in the natural state, both sounds were again distinctly heard. He adduces several arguments drawn from the action of the heart both in its healthy and dis- ' eased state in favour of his opinion; and he ingeniously attempts to get rid of the objection which must instantly suggest itself, that in many cases, such as frequently occur in hyper- trophy of the organ, the loudness of the sounds is diminished, while the force of the impulse is increased, by arguing that in these cases this increased impulse depends rather upon a heaving of the chest produced by the heart, which from its increased size is brought close to its inner surface, than upon a distinct im- pingement upon it, such as takes place in the healthy state. Dr. Hope, M. Rouillaud, Dr. C. J. B. Williams, and the Dublin and London Heart Cominitees have, however, distinctly heard both sounds of the heart, after that por- tion of the chest against which it impinges had been removed. It may, nevertheless, be objected to these experiments, tliat as the stetlioscope was used in many of them, the impulse of the heart against the extremity may have produced ai, effect similar to its impulse against the parietc of the thorax. M. liouillaud, having appa rently this objection in view, states that tlu rubbing of the heart during its movement- against the extremity of the stethoscope, i easily distinguished from the sounds of the heart; and that he has distinctly heard both sounds, though feebler than througli a stetho- scope, as was to be expected when nothing but a cloth was interposed between his naked ear and the surface of the heart. Dr. C.J. B. Williams, in his.experiments, heard both sounds when the stethoscope was placed over the origin of the large arteries, and wliere no external impulse could take place ; and this observation was repeated by the Dublin Committee. The Dublin Committee heard both sounds through the stethoscope, though feebler after the peri- cardium had been injected with tepid water; and in another experiment they were also heard when the ear was simply approximated to the organ. From all these experiments, I think there can be little doubt that the move- ments of the heart, independent of all extra- neous circumstances, are attended by a double sound. As die impulse of the heart against the chest must produce some sound, as any one may convince himself by making the ex- periment in the dead body, and as this occurs during the systole of the heart, or, in other words, during the first sound, it may increase the intensity of that sound. Dr. R. Spittal,* after relating several experiments in which a sound similar to that of the first sound of the heart was heard by tapping gently with the apex of the heart or tiie point of the finger against the chest, both when empty and when filled with water, and after pointing out several sources of fallacy which he supposes were not sufBciendy guarded against in the experiments which we have adduced above as subversive of this view, and which deserve the attention of future experimenters, comes to the conclusion that it is highly probable that the percussion of the heart against the thoracic parietes during the contraction of the ventricles assists mate- rally in the production of the first sound. He is also inclined to believe that the act of the separation of the heart from the thorax after its approach, which was found in his experiment to produce a sharp, short sound, somewhat resembling the ordinary sound, may in certain circumstances be an assistant cause to the second sound.f Magendie's explanation of the second sound is completely untenable. Among those who maintain that these sounds depend upon causes intrinsic to the heart, the first sound is referred by Rouanet, Billing, Bryan, and Bouillaud to the rapid ap])roxima- tion of the auriculo-ventricular valves during the systole of the ventricles, to which Bouillaud • Edin. Med. and Surg. Journal, July 1836. ' t Though Dr. Spittal is inclined to believe that the impulse of the heart against the chest lias con- siderable share in the production of the first sound, he docs not concur witli Majcndie in the explana- tion of the second sound.](https://iiif.wellcomecollection.org/image/b21908503_0044.jp2/full/800%2C/0/default.jpg)
