We will now proceed to consider the Anomalies and Diseases of the Heart, including those of the Valves; but wherever it may prove of great practical interest to acquire a more correct knowledge, both generally and specially, of the anomalies of the valves treated of in the different sections, we purpose, at the close of each, entering more fully into the details of the subject.

We will, moreover, consider simultaneously all original malformations of the heart and of the vascular trunks, not only on account of the unnatural connection existing between them, but also with a view of furnishing the premises necessary for the better comprehension of the appendix on cyanosis, which is subjoined to our remarks on the anomalies of the heart. In order, as far as possible, to facilitate a reference to the most important original malformations, we have arranged the following sections somewhat differently from those by which they are preceded.

1. Deficiency And Excess Of Formation

Absence of the Heart - Acardia - is generally of very rare occurrence, but is a common phenomenon in Acephalia (absence of the brain), especially where there is an absence of the upper half of the trunk. It has only been observed in very rare cases where the nervous system is perfect and complete.

In the consideration of deficiency of the heart we include a series of deficient formations (arrested developments) which may be arranged as follows.

a. The lowest type of formation is that in which a single cavity without valves represents a ventricle in which a dilatation of the vena cava appears as the rudiment of an auricle. The latter is membranous, and the former has only thin muscular walls and weak trabeculae.

b. Next we have a heart consisting of one ventricle and one auricle, with simple vascular trunks, into the former of which opens an aorta, and into the latter a vena cava. In many cases this formation approximates to the succeeding one in which there are two auricles with a single ventricle.

c. In this form there is a single ventricle and one auricle, which is either partially or wholly divided into two cavities by means of a partition wall. The arterial and venous trunks may be either single or separated.

d. Here a capacious ventricle presents the rudiment of a septum ven-triculorum, which becomes so far developed as finally to exhibit only an aperture which is usually situated at its upper extremity. The most common anomaly of the vascular system combined with this form is the origin of the aorta from both ventricles, and the displacement of the pulmonary artery. The foramen ovale in the partition between the auricles remains open. In other cases the septum is perfect, but so situated as considerably to diminish the size of one or other of the ventricles, interfering with its valvular apparatus, and giving the auriculo-ventricular opening a very contracted and even closed appearance, - a condition of things that involves the patency of the foramen ovale and of the ductus arteriosus.

e. Here we have a form of the heart in which the partition between the auricles is defective, although there is a perfect separation of the ventricles. The degree and form of this defective structure are very variable. The septum is sometimes entirely absent, its line of direction being simply indicated by several soft membranous filaments which pass from the posterior to the anterior wall of the common cavity of the auricles. In other cases the rudiment of a septum atriorum developes itself in the form of a crescentic band, either from the arch of the auricle, or below the septum ventriculorum. The wide aperture of communication between the two auricles is round or oval, and has its major axis inclined from before backwards. In other cases, the rudimentary structure is sometimes so far developed round the septum that this deficiency is often represented by a smaller and obtuse triangular aperture; and in other cases, again, the septum seems so far developed from above that it may easily contain a foramen ovale. There are, in this case, two apertures in the partition between the auricles, the former, which depends on defective formation, is not closed, and the latter (the foramen ovale) remains open.

Cases of this nature are generally characterized by a congenital contraction or insufficiency of the aorta, by extraordinary dilatation of the pulmonary artery, and by eccentric hypertrophy of the right side of the heart.

f. In this form the foetal passages, - the foramen ovale, and the ductus arteriosus, - remain open. The degree of the patency of the foramen ovale varies considerably, its valve being very nearly or entirely absent in some cases, but more commonly the upper third or fourth portion of it is wanting, and most frequently of all there is a mere deficiency of attachment at the upper part of the isthmus, by which means a fissure rather than a foramen is formed, which communicates in a very oblique direction from below and behind upwards and forwards from the right into the left auricle. This foetal condition is sometimes persistent to a greater or less degree, and consists in this - that under a marginal projecting rudiment of the Eustachian valve, which penetrates into the anterior columna isthmi fossae ovalis, there is a communication with this fissure-like aperture, or with the still patent foramen ovale. The opening at the upper boundary of the isthmus is either formed as a simple fissure, or consists of several small and roundish apertures. The cause of the patency of the foramen ovale frequently depends on the different malformations of the heart already enumerated, and on the different anomalies of the arterial vascular trunks and of the ductus arteriosus, which still remain to be noticed. The patency of the foramen ovale most frequently corresponds with an incidental arrest of development. In some cases it is associated with smallness of the heart, and retraction of the apex (the foetal condition). It is of very frequent occurrence in its lesser degrees.

The patency of the ductus arteriosus will be more fully noticed in a future page.