THE EFFECTS OF AGING AND DEGENERATIVE VASCULAR DISEASE ON THE MEASUREMENT OF ARTERIAL RIGIDITY IN MAN*

Abstract

The ratio of the fall in pulse pressure times 100 to the related decrease in diastolic pressure following the inhalation of amyl nitrite has been used as an index of arterial rigidity. In previous studies the upper limit of normal for this index was obtained from data on young medical students. Because arteriosclerosis progresses with age, the normal values for this index also should increase with age if it reflects arterial rigidity. Our data on 115 "normal" subjects demonstrated a strong positive correlation of this index with age and were in agreement with in vitro indices calculated from pressure-volume curves of normal human aortas in similar age groups. An equation representing the upper limit of normal separated the arterial rigidity of aging from that of premature arteriosclerosis. The results suggest that this test offers more than just a qualitative estimate of arteriosclerosis. With a knowledge of the variation of normal values with age, the applicability of this test can be extended to all age groups and a more correct interpretation of previous studies utilizing this index can be made.