Plethysmographic characterization of vascular wall by a new parameter--minimum rise-time: age dependence in health

Analysis of the plethysmographic pulse volume contour in terms of "crest time", made in 1940-1960, revealed age dependence and clinically significant variations between health and disease, including arteriosclerosis, hypertension and various dermatoses. A new parameter--"minimum rise-time" (MRT) is suggested and defined from pulse volume contour. In health it was found to be age dependent using finger photoplethysmography. The MRT of the pulse volume is shown by a model 1) to be associated with the mechanical properties (viscoelasticity) of the vascular wall, 2) to approximate the MRT of the pulse pressure, and 3) to be free of ambiguities found in "crest time" and "half rise-time" previously used. The analysis suggests that the gradient of the MRT along peripheral vessels might be a clinical indication of variations in the mechanical properties of the vascular wall.