The Hunterian lectures on malformations of the heart : delivered before the Royal College of Surgeons of England on March 8th, 10th, and 12th, 1909 / by Arthur Keith.

  • Keith, Arthur, Sir, 1866-1955.
Date:
1909
    taken as representative of this group—hearts in which there has been an arrest in the developmental expansion of the infundibular cavity. In the type specimen (Fig. 3) the infundibular cavity is fusiform in shape, measuring 12 millimetres from the orifice by which it communicates with the body of the right ventricle (the ostium infundibuli) to the pulmonary valves above. The lining of the infundi- bular cavity has the appearance of ground glass because the subendocardial tissue is fibro-cellular in texture, and embryonic rather than inflammatory in its microscopic struc- ture. The ostium infundibuli may be as well marked as in the type specimen (Fig. 3), or it may be indicated merely by a circular thickening of the endocardium, or even that indi- cation may be absent. The pulmonary valves in less than half of the hearts of this nature which I have examined—44 in number, of which 16 are in the College collection—were fused to a greater or less degree, the condition of arrest of the infundibulum being thus accompanied by a true pul- monary stenosis. In more than half of these cases—I do not give the exact numbers because in some of the specimens examined the heart was insufficiently opened—an interventri- cular foramen was present; the size of that foramen was variable. In only a small percentage was there an open condition of the foramen ovale or ductus arteriosus. 3. Hearts in which there is almost Complete Arrest in the Developmental Expansion OF THE Infundibulum. A third group of cases represents an almost complete developmental arrest of the infundibulum. The typical con- dition is shown in Figs. 4a and 4b, drawn from a specimen presented to me by Dr. J. A. Milne. The infundibulum is represented by a mere slit or irregular chink situated at the orifice of the pulmonary artery and lined by thickened endocardium. The orifice of the pulmonary artery may be represented by merely a small cicatricial mass or a very small lumen may be present in which the fused semilunar valves can be distinguished. The pulmonary artery, perhaps represented by a fibrous thread at its origin, rapidly increases in calibre as it passes into its point of division into right and left branches. An intraventricular foramen is always present, but only in about 30 per cent, of the cases—which numbered 37 in all—was there a patency of the ductus arteriosus. In such cases the branches of the pulmonary artery are very thin-walled and often greatly dilated. How are they filled with blood in such cases ? The orifice of the pulmonary artery is closed or almost closed. Dr. Bertrand E. Dawson gave me the opportunity of injecting the arteries in a case
    where there was marked congenital pulmonary stenosis. The bronchial arteries and other accessory branches derived from the intercostals were so enlarged that some of them were equal in size to the radial arteries, but one was espe- cially struck by the number rather than by the size of the accessory arterial communications; they formed Fig. 4. Heart of a girl, aged two years, showing complete arrest of the development of the infundibulum, a. Unopened heart viewed from the ventral aspect, b. Right ventricle opened in the same specimen. 1, Pulmonary artery; 2, aorta; 3, position of infundibulum; 4, ostium infundibuli; 5, body of right ventricle and large interventricular orifice; 6, tri- cuspid ; 7, right auricle; 8, left ventricle ; and 9, left auricle. a leash like plexus. The arteries accompanying the phrenic nerves were greatly enlarged and sent branches to the lungs. In those cases where there is complete arrest of the infundibulum, the arterial system of the lungs is filled from the systemic circulation. To merely live—and that is the condition of patients with such hearts—a wonderfully small supply of oxygenated blood is apparently sufiBcient.
    4. Cases in which the Stenosis is merely due to Fusion of the Semilunar Valves. In my list of specimens I have noted 23 in which there was apparently no developmental arrest of the infundibulum yet the pulmonary semilunar valves were united, giving rise to a true condition of pulmonary stenosis. Five of the specimens on my list are in the College collection, but when they were taken out of their jars and examined it was seen that in four of them there was an arrested condition of the Fig. 5.—Pulmonary valves exposed by opening the pulmonary artery in a case of arrested development of the in- fundibulum to show the peculiar form of stenosis. Fig. 6.—The pulmonary valves in a case of stenosis exposed by cutting across the pulmonary artery just above the valves. There is a trace of a third cusp. infundibulum. It is very probable that if all specimens of this nature were so displayed as to show the infundibular part of the right ventricle there would remain only a few in which pulmonary stenosis is present by itself. Still, the condition does occur and is the only form which one could conceive to be the result of a foetal endocarditis. In Figs. 5 and 6 is shown the usual condition of the valves. They are fused so as to form a bell-shaped perforated diaphragm. In most cases traces of only two valves can be made out, but occ.asionally a third can be distinguished. Many patients who suffer from pulmonary stenosis die
    from broncho-pneumonia or other forms of infection ; in such cases it is usual to find the margin of the pulmonary orifice carpeted with vegetations. It is difficult, however, to con- ceive that the peculiar form of the pulmonary valves in these cases could result from an inflammatory condition in the foetus. The condition is totally unlike the stenosis which occurs after birth. Under the microscope the valves, in cases of congenital pulmonary stenosis, are seen to be composed of dense laminated fibrous tissue at their margins, but the body of the valves shows a reticulated tissue distinctly embryonic in character. Fig. 7. Heart showing infundibulum developed but the body of the right ventricle atrophied. 1, Pulmonary artery opened ; 2, infundibulum opened ; 3, ostium infundibuli, leading by an interventricular foramen into left ventricle ; 4, aorta; 5, superior vena cava; 6, right auricle; 7, left ventricle; and 8, left auricle. 5. Cases in which the Infundibulum is Present and THE Body of the Right Ventricle is Small OR Absent. The group of cases I am now going to describe illustrates further the dual constitution of the right ventricle. The type specimen of this group is shown in Fig. 7, drawn from
    a heart sent to me by Dr. F. S. Mackenzie. Here, while the infundibulum of the right ventricle is well developed the body of that chamber is atrophied or obliterated. The con- dition is usually accompanied by a congenital stenosis or complete obliteration of the right auriculo-ventricular orifice. In such cases the foramen ovale is patent, so that the venous blood can pass from the right to the left auricle and ventricle. From the left ventricle part of the blood passes into the infundibulum by a patent interventri- cular foramen. There is also another form in which the infundibular cavity is present and the body of the right ventricle is apparently absent—namely, those cases where the right and left ventricles are unseparated by an inter- ventricular septum. Of the seven specimens belonging to this group five are cases in which the right ventricle is obliterated, two in which the two ventricles form a common chamber. 6. Cases of Subaortic Stenosis. Turning now to the left side of the heart, a condition— very rare, it is true— is found similar in nature to the mal- formations just described on the right side with this difference. The part of the foetal heart from which the infundibulum is derived—the bulbus cordis—normally dis- appears completely from the left side of the heart, but a trace of it may persist giving rise to the condition known as subaortic stenosis—a condition which has hitherto not received a satisfactory explanation. Thus, while the abnormality on the right side of the heart depends on an arrest of growth, that on the left side depends on an arrest of atrophy. The type specimen, which belonged to the museum of the London Hospital, and was lost in the disastrous fire at Toronto University, is shown in Fig. 8. Just below the orifice of the aorta a fibrous collar is seen to surround the infundibulum of the left ventricle. It is formed by an irregular thickening of the endocardium. The ostium infundibuli is in every way homologous to the corresponding abnormal constriction which occurs in the right ventricle. I have seen only four hearts showing subaortic stenosis—one in the museum of St. George’s Hospital, one in St. Bartholomew’s, one in Guy’s, and the one figured here. We have, unfortunately, no specimen in the College collection. 7. Cases of Congenital Aortic Stenosis. The condition of congenital aortic stenosis is rare in England. Altogether I noted only four cases in the museums of the metropolitan medical schools. The malformation is apparently much more frequently seen in St. Petersburg, for