DETERMINATION OF 'SIZE OF HEART BY X-RAYS 44^ 



and the great individual variations found in the transverse di- 

 ameter the averages in my own cases correspond fairly well with 

 the standard. Dietlen's cases studied in the supine position 

 show a greater transverse diameter than the standard which is 

 based on the sitting position. On the other hand, the individuals 

 studied by Otten show an average difference of 0.43 cm. below 

 the standard for each group. This is probably due in the main 

 to the fact that the individuals were relatively slender, averaging 

 3.2 per cent above the normal height for the average weight at 

 age thirty, as given in tables A and B. Yet Otten gives the 

 position of the long axis of the heart in the individuals studied 

 by him in the supine position as obliquely placed in 35 per cent 

 of the cases, perpendicularly placed in 13 per cent and trans- 

 versely placed in 52 per cent so that in over half the cases the 

 transverse diameter should be relatively large. The individuals 

 studied by Claytor and Merrill have unusually narrow hearts. 

 The upright position chosen by these investigators may have 

 tended to bring the heart into the vertical position but with due 

 regard for this the hearts seem to average abnormally narrow. 



In general it may be said that for the supine or prone position 

 about 7 per cent should be added to the transverse diameter over 

 the figures given in the standard table ; for the standing position, 

 about 4 per cent should be subtracted. 



I have found in seven cases at the end of deep inspiration in 

 the prone, sitting and standing positions that the transverse 

 diameter averaged respectively 14.1, 13.1 and 12.6 cm. In these 

 the average for the prone position was 7.6 per cent greater than 

 for the sitting, 3.8 per cent less for the standing than the sit- 

 ting position. In eight cases studied during normal respiration 

 but at the height of inspiration in the sitting and prone positions, 

 the average transverse diameter sitting was 13.3, prone, 14.3, or 

 7.5 per cent greater in the prone than in the sitting position. In 

 deep inspiration the change in the transverse diameter corresponds 

 with the change ^in the area of the heart silhouette but in quiet 

 inspiration the heart is relatively broader in the prone than in 

 the sitting position. 



