54 C. W. M. Poynter 



of the heart may act independently of, and without disturbing 

 the normal processes of, the remainder of the body. When the 

 physiological function of the circulatory system is seriously inter- 

 fered with by this anomalous development of some portion or 

 portions of the heart it appears that a compensation through 

 arrest or over development of normal parts is attempted in some 

 instances, but with our present knowledge it is not possible to 

 distinguish between primary lesions and secondary effects. 



As has been found in the arteries, factors disturbing develop- 

 ment of the heart apparently act at a very early age and on very 

 restricted areas. A sufficient number of isolated lesions have 

 been encountered to make it a comparatively easy problem to 

 break up any complex into its individual elements for the pur- 

 poses of analysis. 



We are able to interpret many anomalies in their relation to the 

 orderly course of development, but the actual factors producing 

 them are not revealed or even suggested by this method of study. 

 Prenatal inflammations and endocarditis can be apparently disre- 

 garded as primary disturbing factors. 



Near 40 per cent, of the hearts presented but a single lesion, 

 while the total number of separate lesions encountered in the 

 886 hearts was 1,978, or 3^ lesions for each heart showing more 

 than one. Certain complexes were more frequent than others, 

 but no associated lesions were so constant as to be in any way 

 instructive. Other bodily anomalies were occasionally found in 

 association with those of the heart, but none constantly or in any 

 way suggestive of a relation to any specific cardiac lesion. 



The statement has frequently been made that the right side 

 of the heart is more susceptible to developmental disturbances 

 than the left ; this would certainly seem to be true if we consider 

 only the aortic and pulmonary trunks, but if we consider all 

 anomalies as revealed by this study such a claim cannot be sub- 

 stantiated. 



There are no particular diseases to which cases suffering with 

 congenital cardiac lesions are especially susceptible. There are 

 no pathognomic symptoms surely indicating the condition of 

 anomaly. Congenital cyanosis is not a common symptom, in- 

 deed it is not present in one third of the cases. 



