K. Takazawa et al., ASSESSMENT OF VASOACTIVE AGENTS AND VASCULAR AGING BY THE 2ND DERIVATIVE OF PHOTOPLETHYSMOGRAM WAVE-FORM, Hypertension, 32(2), 1998, pp. 365-370
To evaluate the clinical application of the second derivative of the f
ingertip photoplethysmogram waveform, we performed drug administration
studies (study 1) and epidemiological studies (study 2). In study 1,
ascending aortic pressure was recorded simultaneously with the fingert
ip photoplethysmogram and its second derivative in 39 patients with a
mean+/-SD age of 54+/-11 years. The augmentation index was defined as
the ratio of the height of the late systolic peak to that of the early
systolic peak in the pulse. The second derivative consists of an a, b
, c, and d wave in systole and an e wave in diastole. Ascending aortic
pressure increased after injection of 2.5 mu g angiotensin from 126/7
4 to 160/91 mm Hg and decreased after 0.3 mg sublingual nitroglycerin
to 111/73 mm Hg. The d/a, the ratio of the height of the d wave to tha
t of the a wave, decreased after angiotensin from -0.40+/-0.13 to -0.6
2+/-0.19 and increased after nitroglycerin to -0.25+/-0.12 (P<0.001 an
d P<0.001, respectively). The negative d/a increased with increases in
plethysmographic and ascending aortic augmentation indices (r=0.79, P
<0.001, and r=0.80, P<0.001, respectively). The negative d/a reflects
the late systolic pressure augmentation in the ascending aorta and may
be useful for noninvasive evaluation of the effects of vasoactive age
nts. In study 2, the second derivative of the plethysmogram waveform w
as measured in a total of 600 subjects (50 men and 50 women in each de
cade from the 3rd to the 8th) in our health assessment center. The b/a
ratio increased with age, and c/a, d/a, and e/a ratios decreased with
age. Thus, the second derivative aging index was defined as b-c-d-e/a
. The second derivative wave aging index (y) increased with age (x) (r
=0.80, P<0.001, y=0.023x-1.515), The second derivative aging index was
higher in 126 subjects with any history of diabetes mellitus, hyperte
nsion, hypercholesterolemia, and ischemic heart disease than in age-ma
tched subjects without such a history (-0.06+/-0.36 versus -0.22+/-0.4
1, P<0.01). Women had a higher aging index than men (P<0.01). The b-c-
d-e/a ratio may be useful for evaluation of vascular aging and for scr
eening of arteriosclerotic disease.