These are either congenital and original, or acquired. The former are very numerous, and admit, in part, of being referred to an arrest of development. Many depend on different adhesions of the heart resulting from inflammation in the foetus, and some again on different anomalies of neighboring organs, as, for instance, on the deficient development of a lung, the partial deficiency of the diaphragm, and the position of the abdominal viscera in the thorax. These anomalies are very various in their character, and the most important, together with the vascular anomalies included in this case, are as follows:

Position Of The Heart Exterior To The Body

This anomaly occurs associated with a partial absence of the diaphragm and the abdominal and thoracic walls. Where the former of these is absent, the heart is generally situated with all or several of the viscera externally to the body, in a closed or open sac occasionally contained in the sheath of the umbilical vessels.

Position Of The Heart Within The Body, But External To The Thoracic Cavity

According to the direction in which the heart is placed, it assumes either a cervical position (ectopie cephalique), or an abdominal one (Breschet).

Anomalous Positions Of The Heart In The Thoracic Cavity

These possess various points of interest from their presenting considerable analogy with many acquired anomalous positions of the heart, and also on account of their apparently arising from similar conditions. To these belong the position of the heart on the right side, without the simultaneous transposition of other viscera, its perpendicular position in the centre of the thoracic cavity, its horizontal, oblique positions, etc.

Anomalous Origin Of The Vascular Trunks

To this class belong:

The displacement of the aorta towards the right side, and its origin from both ventricles, associated with a defect in the ventricular septum; or the aorta may take its origin, conjointly with the pulmonary artery, from the right ventricle, where no such anomaly exists. We sometimes find a similar relation of the pulmonary artery, that is to say, it takes its origin from both ventricles, or conjointly with the aorta from the left ventricle. This vessel has also been observed to spring from abnormal positions in the right ventricle.

Many anomalies of the systemic and pulmonary veins, as, for instance, the opening of a left descending vena cava into the auricle, an opening of the pulmonary veins of the right side into the right auricle, into the upper vena cava, etc, also belong to this class.

Actual transposition may exist with reference to the heart alone, or conjointly with the thoracic and abdominal viscera generally. A more important transposition is, however, that affecting the vascular trunks, which often present the anomaly of the aorta, springing from the right, and the pulmonary artery from the left ventricle, while the veins open normally. Otto found, in the case of a double monster, that the venae cavae opened into the left, and the pulmonary veins into the right auricle, while the arterial trunks presented the normal mode of origin.

The acquired changes of position of the heart are very numerous, but as they are merely secondary phenomena, they generally possess a very subordinate interest. An exception occurs, however, in the case of those anomalies of position of the heart, which arise from empyema, pneumothorax, pulmonary emphysema, atrophy of the lungs, etc, and which are of great importance with regard to diagnosis.

The majority of these consist in a displacement of the heart from its normal position. It may occur in the most opposite inclinations either to one or the other side, or downwards, upwards, forwards, or backwards. The most common causes of these displacements are, on the one hand, excessive dilatation of one or other of the pleural sacs from exudations into its cavity, from pneumothorax, or pulmonary emphysema; and on the other, the formation of a vacuum in it by the cure of chronic pleurisies, by wasting and atrophy of the lungs consequent on indurated pneumonia, by bronchial dilatation, etc. The displacements of the heart towards one or the other side resemble similar congenital and original anomalies of the heart's position. A change in the position of the heart is but rarely occasioned by pneumonic and tuberculous enlargements of a lung, and still more unfrequently by an acquired position of the abdominal viscera in one side of the thorax, arising from laceration of the diaphragm, etc. The heart may likewise be differently displaced from its position by aneurisms of the aorta, the contiguity of voluminous adventitious products, etc. Flatulence, extreme ascites, and large adventitious products in the abdomen, may also displace the heart in an upward direction; whilst a corresponding anomaly in the position of the heart is likewise induced by curvature of the spine, irregularity in the form of the thorax, etc.

In contrast with the above-named anomalies, this change of position may sometimes be spontaneous, in consequence of the heart assuming an anomalous position and anomalous relations of contact with the diaphragm and ribs, arising from an uniform or a varying enlargement, and from its simultaneous increase in weight.