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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![<(eems tohavebeen almost implicitly adopted un- itil the appearance of a paper by the late Professor iTurner, in 1829. Professor Turner there re- called to the attention of medical men the Dbservations of Harvey, Lancisi, Senac, and lllaller, upon the order of succession in which lithe cavities of the heart contract, which appear iito have been forgotten amidst admn-ation at I the brilliancy of Laennec's progress. He also ipointed out from their experiments that if the Msecond sound was dependent upon the con- ilraction of the auricles, it ought to precede i instead of following the first sound, and that i the pause ought to occur after the first sound, ..and not after the second. He also adduced, in (farther ])roof of Laennec's error, observations dirawn from the effects of disease, when, from s6ome impediment to the passage of the blood lifrom the right auricle into the ventricle, a dis- t.tinct regurgitation takes place into the large \tems at the root of the neck, and showed that iiin these cases the regurgitation marking the tcontraction of the auricles occurs without any aiccompanying sound ; that immediately after- \wards the impulse is felt attended by the first ■sound, and that the second sound takes [place during the diastole of the ventricles aaud the passive condition of the auricles. IHe suggested that the second sound might be accounted for by the falling back of the heart ir.nto the pericardium during its diastole, to which the elasticity of the ventricles at the [Commencement o the diastole, attracting the lliluid by suction from their corresponding auri- ibles, may perhaps contribute. Soon after the ijippearance of Mr. Turner's paper, Laennec's ;3xplanation of the cause of the second sound iiippears to have been pretty generally aban- il3oned ; and numerous attempts, both in this :ountry and in France, have since that time seen made to solve this difficulty. Some of I .hese explanations appear to be mere guesses, >Dccasionally at total variance with the anato- imical structure of the organ, and at times pre- leenting even as wide a departure from its nor- imal action as that given by Laennec himself. Others, again, have entered upon an experi- mental investigation of the subject with en- lightened views of its anatomy and physiology, laave furnished us with much additional infor- mation, and lead us to indulge in the pleasing lorospect that in a short time the matter will be completely set at rest. The result of the experiments of Hope and Williams, attested a.s they have been by various (gentlemen well qualifiied to judge of their occuracy,—also those of JVIr.Carlisle, Magendie, Bouillaud, and the Dublin Committee, have satisfactorily determined that the account of the mrder of the contractions of the heart, and iiheir isochronism to the sounds as stated by \Mr. Turner, are perfectly correct. As, how- ' • !ver, so many different circumstances attend ■ac:h movement of the heart, any one of which nay be capable of producing these sounds, it Kjcame a much more difficult matter, and one '•quiring great perseverance and accuracy of iivestigation,to determine upon what particular y^'ne or more of these, each sound depends. For accompanying, and synchronous with the first sound, we have the contraction of the ven- tricles, tiie collision of the different currents of blood contained there thus set in motion, the approximating of the auriculo-ventricular valves, the impulse of the heart against the chest, and the propulsion of tlie blood along the large arteries; while attending the second sound, we have the diastole of the ventricles, and the rush of a certain quantity of blood from the auricles into the ventricles, the sudden separation of the auriculo-ventricular valves towards the walls of the ventricles, and the regurgitalion of part of the blood in the arteries upon the semi- lunar valves, throwing them inwards towards the axes of the vessels; so we will find that each of these in its turn has been thought ca- pable of producing the sound which it accompa- nies, and stillhas,oruntil lately had, its advocates and supporters. As the subjectisonesurrounded with numerous and unusual difficulties, and is of comparatively recent investigation, it has fol- lowed, as was to be anticipated, that as new facts and observations are collected, many of the opinions first promulgated on this question have required to be modified or changed ; and the scientific candour displayed by several of these authors in renouncing former published opinions is deserving of the highest praise. Several of the explanations of the cause of the sounds of the heart proceed, however, upon the supposition that the relation of these sounds to the movements of the organ is different from what has been here represented. We shall merely state these without alluding to the arguments adduced in support of them, as we believe that they are founded upon inaccurate observation. Sir D. Barry believed that the first sound was synchronous with the diastole of the auricles, and the second sound with the diastole of the ventricles. Mr. Pigeaux, Dr. Corrigan also untd lately, Dr. Stokes, Mr. Hart, and Mr. Beau, have maintained that the first sound is synchronous with the diastole and not with the systole of the ventricles. Ac- cording to Mr. Pigeaux, when the auricles contract they project the blood against the walls of the ventricle, and a dull sound (first sound) is produced ; on the other hand, whilst the ventricles contract, they project the blood against the thin walls of the great vessels which spring from them, and a clear sound (second sound) is the result. Dr. Corrigan supposed that the first sound was produced by the rush of blood from the auricles into the dilating ventricles, and that the second sound owed its origin to the striking together of the internal surfaces of the ventricles during their contrac- tion, after they had expelled all their blood. Mr. Beau believes with M. Magendie that the first sound arises from the impulse of the heart against the inner surface of the chest, but difl^ers from him in maintaining that this occurs during its diastole, and not during its systole. The second sound he believes to depend upon the dilatation of the auricles. M. Piorry has revived the obsolete and perfectly untenable opinion of NichoU, that the two ventricles contract at different times, and attributes](https://iiif.wellcomecollection.org/image/b21908503_0043.jp2/full/800%2C/0/default.jpg)
