The pulmonary circulation in cystic fibrosis.

The hearts and lungs of 36 patients dying of cystic fibrosis have 
been studied to establish the relationship between right ventricular hypertrophy (RVH), 
pathological changes in the pulmonary circulation, and the clinical features. The 
presence and degree of RVH were measured by Fulton's technique of 
weighing the ventricles separately. Of the subjects who died after the 
age of 3 years, one in six had no RVH, although 
the mean age of this group was not significantly different from 
that of the remainder. There was no correlation between duration of 
cyanosis, haemoglobin levels, and RVH. Although not statistically significant, the cases 
without RVH tended to have had clubbing of the finger-nails for 
longer periods before death. The electrocardiogram was useful in the diagnosis 
of RVH. Right ventricular hypertrophy was common in children with lungs 
of large volume as judged by the radiographic centile of lung 
length. Cases with RVH show reduced background haze in the arteriogram 
and fewer arteries per unit area of lung. For the first 
time thickening of the medial muscle layer proportional to the degree 
of RVH has been demonstrated, only in the smaller arteries. Arterial 
subintimal fibrosis is more common in cases with RVH, as is 
thickening of the walls of small pulmonary veins. The implications of 
these findings are discussed. 