The Hunterian lectures on malformations of the heart : delivered before the Royal College of Surgeons of England on March 8th, 10th, and 12th, 1909 / by Arthur Keith.

  • Keith, Arthur, Sir, 1866-1955.
Date:
1909
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Licence: In copyright

Credit: The Hunterian lectures on malformations of the heart : delivered before the Royal College of Surgeons of England on March 8th, 10th, and 12th, 1909 / by Arthur Keith. 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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    LECTURE II. Delivered on March 10th. Transposition of the arterial stems.—If the theory of a bulbus element in the human heart helps us to understand the numerous abnormalities which were discussed in my last lecture, it is of even greater assistance in clearing up the various abnormal and very puzzling conditions included under the term of transposition of the aorta and pulmonary artery. The pulmonary artery in these cases of trans- position arises behind the aorta, over the left ventricle, while the aorta springs from the infundibulum of the right ventricle. Thus the venous blood is thrown by the right side of the heart into the aorta and systemic circulation while the arterial blood is carried back to the lungs by the pulmonary artery. Altogether I have examined 25 hearts in which the arterial trunks were transposed, six of them being in the College collection. Fig. 11 shows the arrange- ment of parts in a specimen which may be regarded as typical of the group. The aorta, recognised not only by its distribution but also by the fact that the coronary arteries are given off from it, arises from the infundibulum of the right ventricle - that part of the ventricle which is derived from the bulbus cordis. The pulmonary artery occupies the position of the aorta and springs from the left ventricle. The exact condition of parts is best seen by examining a section made at the base of the heart (Fig. 12). In the normal heart the aortic orifice is situated behind the pulmonary orifice and immediately anterior to the left auricle and left auriculo-ventricular orifice. The aortic cusps corresponding to the origin of the right and left coronary arteries—right and left coronary cusps—are situated towards the sternal margin of the aorta, the non-coronary towards the dorsal margin. In the abnormal heart the position of parts is reversed ; now the aorta is in front and the pulmonary artery behind ; the position of the aortic cusps is reversed, the non-coronary cusps being now not on the dorsal but on the sternal margin of the aorta. Further, it is to be noted that the aorta arises from the infundibulum or persistent bulbus cordis, while the pulmonary artery arises directly from the left ventricle, the part of the bulbus corresponding to it ha^fing atropied, but the atrophy is some- times only partial. How is transposition brought about? The explanation offered by Rokitansky—the only explanation yet given—is that the aortic end of the heart may undergo an abnormal