2 Gruber, Virchow's Archiv, 1865.
More serious congenital malpositions, but of less practical importance, are the cases of ectopia cordis, which may exist in all grades, from simple failure of closure in the sternum—fissura sterni—to the most extreme condition, in which the naked heart lies outside the chest-wall. Hodgen3 and March4 have each described remarkable examples of the latter condition. In other instances the heart lies free in the neighborhood of the neck, or it may be in a congenital umbilical hernia.
3 American Practitioner, xviii. p. 107.
4 Trans. of the New York State Medical Society, 1859.
The malpositions with which we are more immediately concerned arise from disease of the heart itself or its membranes, or from disease of contiguous organs.
We judge of the situation of the heart by the site of the apex-beat, by the position and extent of the area of dulness, and by the character of the sounds. So constant in health is the position of the apex-beat in the fifth intercostal space that in our examination of the heart we seek first to determine its existence as affording the most important information of the normal situation of the organ. The area of dulness is a much more variable guide, depending as it does so greatly on the degree of distension of the lungs. When, as sometimes happens, neither apex-beat nor area of dulness can be obtained, the position of maximum intensity of the heart sounds becomes an important indication.
In regard to the effect of respiratory movements in the position of the heart, with each inspiration it is drawn down slightly by the descent of the diaphragm, and it is separated from the chest-wall by the inflation and descent of the left lobe of the lung—in deep inspiration to such a degree as to obliterate the area of dulness and to prevent the systolic impulse from reaching the intercostal space.
The effect of gravity on the position of the heart is well illustrated by the more forcible and extended beat when the chest is bent forward or when the person is turned toward the left side—procedures frequently resorted to when from any cause the apex-beat is obscure.
Of diseases of the heart itself, dilatation and hypertrophy are very common causes of displacement, and in general enlargement the organ may occupy a very considerable part of the left side of the chest, and the apex-beat in the seventh or eighth space in the axillary line. Hypertrophy of the left ventricle alone pushes out the apex-beat, while enlargement of the right ventricle gives a stronger impulse toward the left border of the sternum and a more marked pulsation below the ensiform cartilage. Hypertrophy and dilatation of the auricles increase the width of the cardiac dulness, and may cause marked pulsation in the second and third spaces on either side of the sternum.
In pericardial effusion the heart is pressed backward and the apex slightly raised.