MALFORMATIONS OF THE BULBUS CORDIS 9 



infundibulum and body of the right ventricle have developed to a 

 normal extent but they have never completely fused, a constriction 

 remaining between them, representing the ventricular orifice of the 

 bulbus. A typical specimen is shown in figure 3. It is the heart of a 

 young man who sought treatment at the London Hospital, and was for 

 two months under the care of Dr. Percy Kidd, to whom and to Dr. F. J. 

 Smith I am indebted for the opportunity of examining this specimen. 

 The infundibulum is enormously dilated as may be seen from the figure, 

 and is sharply separated from the body of the right ventricle by a 

 muscular partition, which is perforated by an orifice, 10 mm. in diameter. 

 The orifice is surrounded by dense fibrous tissue which resembles, in 

 structure, the tricuspid valve. Just below the orifice is seen a small 

 interventricular foramen (see figure 3, between 4, 5). The infundibular 

 raphe (between A and B), ends at the bulbar orifice ; the septal bands A 

 and B are wide and well marked. The fibrous tissue round the constric- 

 tion I regard as a representation of the valves and fibrous tissue at the 

 lower orifice of the bulbus cordis (see figure i). This condition is 

 certainly not common, but in the same week as I obtained the specimen 

 figured here, 1 received another from Dr. John Hay of Liverpool. It 

 was the heart of a woman who had reached middle age ; the infundibulum 

 was smaller and its orifice not so narrow, as in the specimen figured 

 here. Altogether, I have had an opportunity of examining 15 specimens 

 of this type, and about 50 cases are recorded. In some of them the 

 constriction between the infundibulum and body of the ventricle is but 

 slight, and the fibrous tissue of the margin is represented by a ring of 

 irregular endocardial elevations. The explanation which has hitherto 

 been offered of such a condition is that it is the result of cicatrisation 

 following an endocardial lesion. Evidence in support of such a hypo- 

 thesis is entirely lacking. 



The second class of cases which I now proceed to deal with are 

 common, and are usually described as congenital stenosis of the 

 pulmonary artery ; they are, in reality, due to an arrest of development 

 of the bulbus cordis. In the first class of cases, just described, there was 

 no arrest of development of the infundibulum — the condition was due 

 simply to a persistance of the lower bulbar orifice. In this group, how- 

 ever, the condition is different (see figure 4) ; usually the bulbus is only 

 partly expanded ; the endocardial lining is thick and frequently cor- 



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