11EART, ABNORMAL CONDITIONS OR—There is no organ in the body in which the variousdeviations from the normal state have been more diligently or more carefully explored than the heart ; nor ought it to be otherwise, when we take into account the important part which the heart performs in the organism, and the serious nature of the derangements which its diseases in general produce,—how many or gans and how many functions are involved in the break-up which too often follows the oc currence of morbid alterations of the heart. The great frequency* of diseases of this organ, and the manifest and tangible shape which these diseases assume, as well as the little liability of its component structures to those appearances which have been denominated pseudo-morbid, these circumstances render it comparatively easy to detect and observe its abnormal condi tions. To one who has made the natural condition of the whole organ, as well as of its several parts, the subject of careful study, there is no field of investigation in morbid anatomy which presents fewer difficulties.
The records of anatomy are not without in stances of total absence of the central organ of circulation (acardia); and it may well be supposed that such cases would also afford examples of the defective development of other not less important organs. In short, it is in ace plialous and anencephalous fcetuses that the heart is most frequently wanting, although its ab sence is not, as some observers suppose, a con stant characteristic of these forms of monstro sity ; nor on the other hand does acardia ne cessarily imply acephalia or anencephalia. Thus in the case recorded by Marriguest, and quoted at length in Breschet's Memoir Sur l'Ectopie du CTur,1 the brain was present, while all the usual contents of the thorax were wanting, their place having been supplied by a large bladder full of clear water which occu pied the whole thoracic cavity. The details of another case were communicated many years ago to the Royal Society by Sir Benjamin Brodie, and are published in the volume of their Transactions for 1809. The fcetus was one of twins, as is most frequently the case when the heart is absent. The brain was " nearly the natural size, and nothing unusual was observed in it." The heart, thymus gland, and pleura were absent, and the lungs most imperfectly developed. The aorta, however, was tolerably perfectly developed, but as a con tinuation of the umbilical artery extending from the left groin upwards on the fore-part of the spine to the upper part of the thorax, where it gave off the two subclavian, and afterwards divided into the two carotid arteries without forming an arch. The external and internal
iliac arteries of the left side came from this artery in the left groin immediately after it left the umbilicus, and the common iliac of the right was given off from it in the lumbar region after it had gained the situation of the aorta.
We shall first examine the congenital devia tions from the normal state in this organ, and secondly its morbid alterations.
1. Congenital abnormal conditions.—These are observed under three heads. 1. Congeni tal aberrations of position, or ectopim of the heart. 2. Malformations by defect in deve lopement. 3. Malformations by excess of de velopement.
1. Congenital aberrations of position.—The simplest form of malposition is that in which the heart retains the vertical position which it occupies during the early periods of intraute rine life ; but of this the authentic instances are rare.* Better known is that deviation in which the heart is directed downwards, forwards, and to the right side. This malposition generally occurs as a part of a universal transposition of the abdominal and thoracic viscera, of which many well-marked examples are now on re cord ; however, it sometimes, although more rarely, exists alone without ectopia of any other organ. Breschett records four cases of this latter kind. Out:it has met with three in stances, and many other examples are scattered among the records of anatornists.§ In this form of transposition of the heart, the aorta sometimes passes down along the right side of the spine, and at other times down its left side. In the latter case the transposition is not so complete, the ventricles retaining their natural position with reference to the anterior and pos terior aspects of the body. Again the heart may be pushed too much to the left side, as a mechanical result of congenital diaphragmatic hernia of the right side; and it has been found laid across in the chest from one side to the other, the apex being at one time directed to the right side, and at another to the left, or turned upside down, the base toward the abdomen, or in that cavity, the apex upwards still remaining in the thorax.