MALFORMATIONS OF THE BULBUS CORDIS II 



this form of infundibulum ; the right interpretation appears to be that 

 these congenital constrictions are specially susceptible of becoming the 

 site at which vegetations form. 



In the third class of cases of malformation of the bulbus cordis, the 

 arrest of development is more complete than in the second class, but of 

 course stages intermediate to these two classes occur. The condition is 

 shown in figure 5, where the heart of a boy aged 6 yrs. with the right 

 ventricle laid widely open is represented. The infundibulum is small 



Figure 5, heart of a boy aged 6 with the right ventricle laid widely open. 



(i) Pulmonary artery. 



(2) Aorta also laid open ; below its orifice is seen a wide interventricular foramen 



leading into the left ventricle. 



(3) Infundibulum or bulbus arrested in its expansion. 



(4) (5) Lower orifice of infundibulum or bulbus. 4 represents septal band A 



in section (see figures 2, 3, 4). 



(6) Body of right ventricle. 



(7) Tricuspid valve. 



(8) Left ventricle. 



(9) Right auricle. 



(7 mm. in depth, 4 mm. in width), lined by opaque thickened endocardium, 

 with a well-marked narrow lower orifice, formed by a fibrous thickening 



(65) ^ 



