In such cases as have been just detailed, the heart still retains its title to be considered as a thoracic viscus ; but other and more re markable malpositions of it have been found, where it is excluded from that cavity. These are, in fact, congenital thoracic hernime in va rious directions, of which Breschet, whose memoir already referred to contains the most complete account of this subject, enumerates three principal varieties, according to the situ ation in which the heart is found, viz. the superior or cervical displacement, the abdo minal or inferiur, and the thoracic or anterior.
Thus 13reschet details a case in which the heart, lungs, and thymus gland were all con tained in the anterior part of the neck, forming a large tumour under the lower jaw. The point of the heart was attached to the base of the tongue, and placed between two branches of the lower jaw. The thorax was occupied by the abdominal viscera, which had passed up through a fissure in the diaphragm. In a second instance of this high displacement the apex of the heart adhered to the palate; but in this case the malposition appears to have been owing to a morbid adhesion of the umbilical cord to the head, by which all the viscera were drawn out of their natural positions. A less degree of cervical displacement is where the heart is found immediately above the thorax, in the front of the neck, which, however, is very rare.
When the malposited heart is found in the abdomen, the diaphragm is generally deficient to a greater or less extent.
In a case narrated by Mr. Wilson,* the heart was in a fissure on the convex surface of the liver—the infant lived seven days I Itamel also gives an instance of the heart being placed in the region of the stomach, and the indi vidual in whom he observed it was ten years of age. And in the extraordinary case related by Deschamps, the heart occupied the place of the left kidney I Not the least marvellous cir cumstance about this ease is, that the indi vidual was an old soldier, who had served several campaigns, and enjoyed excellent health, with the exception of nephritic pains, which ultimately procured him his discharge from the service. The right kidney alone existed, and was found in a state of suppuration.f The vessels emanating from the heart passed through an opening in the diaphragm into the thorax.
Dr. Paget mentions some instances of vari eties of position which parts of the heart may assume with respect to each other. In a case recorded in the first volume of the Edinburgh Medico-ChirurgicalTransactions by Dr.l Iolmes of Canada, the right auricle, enlarged to the capacity of a pint, was found to open into the left ventricle in place of the right, into which, however, the blood afterwards found its way through a small perforation in the septum of the ventricles.
The aorta and pulmonary artery may arise from one ventricle alone, either right or left, and instances of each prteternatural origin are pre served in the museum of the Edinburgh Col lege of Surgeons.
When the anterior wall of the thorax is de ficient, the heart may be found protruding through the opening, as in fissure of the ster num, or a defect in its inferior portion as well as in some of the ribs; nor does this mal position necessarily destroy life. Where the deficiency is not confined to the wall of the thorax, but also extends to the abdomen, the stomach, liver, and spleen, with the heart, are found occupying a large hernial sac in front of the opening, which is sometimes contained in the sheath of the umbilical cord, or covered by an extension of the common integument. In the case of simple fissure of the sternum, it has occurred that the heart had not protruded, but occupied its natural position, being simply exposed to view by the abnormal opening in the chest.* 2. Malformations by defect in development. —Our limits compel us to restrict the present account to little more than an enumeration of the congenital malformations which may be placed in this class. In these malformations we find a diminution in the normal number of the heart's cavities, either from a very early arrest in the developement of the whole organ, or from a total non-developement of the sep tum, or from its imperfect developement. A few rare instances, many of which have oc curred in the lower quadrupeds, of an ex tremely imperfect state of the heart, are quoted by Otto, in which that organ seemed to consist of nothing but a fleshy enlargement at the commencement of the aorta, described as " a mere fleshy mass without any cavity," or " a longish solid mass from which the vessels arise," " or a mere expanded vascular trunk." The dicalions heart of Hunter, or that with two cavities, exists at a very early period of the developement of the Mammiferous embryo : it is described and figured by Baer in the em bryo of a dog, of three weeks, only four lines in length, as consisting of a single auricle and a single ventriele.f The permanence of this state of the heart, similar to the natural con dition of that organ in fishes, constitutes one of the simplest but rarest malformations in the human subject. From the ventricle a single vessel arises which subdivides into the aorta and pulmonary artery. A very perfect example of this malformation is described by Mr.Wilson in the Philosophical Transactions for 1798 ; it is the same case which has been already al luded to as affording an instance of malposition. In this case the blood was returned from the lungs by two veins which joined the superior vena cava, and entered the auricle along with it, the inferior cava being formed in the usual way. Other examples are recorded by Mr. Standert,/ Dr. Farre,§ Professor Mayer,11 and Dr. Ramsbotham.1 The heart with three cavities (tricoilia of Hunter), that is, containing two auricles and one ventricle, or that form of the heart which belongs to the Batrachian reptiles, must be very rare, if indeed it ever occurs.