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.