CONGENITAL MALFORMATIONS AND DISPLACEMENTS OF THE HEART.
Ectopia Cordis. Cyanosis, pervious foramen ovale. Symptoms, blue mucosæ, coldness, staring coat, unthriftiness. Unequal to exertion, palpitations, murmur before the first heart sound. Obstructed circulation in the lungs as a cause of cyanosis, cyanosis as a cause of lung disease.
These have been much less frequently observed in the lower animals than in man. The anomalies observed in mammals include the following: The displacement of the heart to the right side of the chest; displacement entirely out of the chest (ectopia cordis); permanent communication between the right and left auricles (cyanosis); entire absence of heart; two hearts; one common ventricle communicating with two auricles as in reptiles; three ventricles; only one auricle; absence of one or several valves; absence of the pericardium; variations in the mode of connection of the heart and large vessels, etc.
Displacements of the heart have been especially studied by Hering on calves. The breast bone remained as originally developed in two lateral halves, and the heart remained outside connected with the interior of the chest only by its large vessels. The heart thus exposed and covered only by its investing membrane (pericardium) afforded an excellent opportunity to study its action, of which Hering freely availed himself. Animals affected in this way survived their birth but a very short time. An approach to this condition was thirty years ago made familiar to the medical world in the person of M. Gouz, a German mechanic, the movements of whose heart could be easily watched through a fissure in the breast bone.
Permanent communication between the two auricles. Pervious foramen ovale. Cyanosis. Previous to birth there is an opening between the right and left auricle, allowing the blood to flow from the former into the latter in place of, as in after life, descending into the right ventricle and thence circulating through the lungs. At birth this is contracted, and in a few days is completely closed in accordance with the new life, which demands that all blood must circulate through the lungs in order to its æration. Sometimes this fails to be effected, and venous blood from the right side of the heart continues to mix with arterial in the left, deteriorating it in quality and unfitting it for nutrition, secretion, calorification, and other essential processes. The semi-venous blood circulating in the arteries gives a bluish hue to the visible mucous membrane, hence the name of the blue disease. This blood is unfit for sustaining the vital changes essential to the production of animal heat, so that the animal suffers from coldness of the surface and extremities, staring coat and general unthrifty appearance. Such subjects grow badly, and refuse to lay on flesh, but are said to arrive at maturity in some instances and to have their imperfection recognized only because of the short breathing, and irregular heart’s action when subjected to exertion. A heart murmur preceding the first sound of health is usually present, as in anæmia.
Drs. Abernethy and Wardrop draw attention to the frequency of previous foramen ovale in the human subject in connection with pulmonary consumption, and opine that it is reopened as a consequence of this disease. The coincidence has not been observed in the lower animals, though if it were found to exist the question would arise whether the deterioration of the blood and general health in open foramen ovale did not also favor the deposit of tubercle in the lungs. When from deficient ventilation the atmosphere and blood become impregnated with carbonic dioxide the production of tubercle in man or in animals is correspondingly frequent.
The subjects of previous foramen ovale die young or prove worthless when they arrive at maturity. Nothing can be done to ameliorate the condition.