[Assessment of arterial compliance and elasticity during graded head-up tilt in healthy people]

Abstract

Head-up tilting causes many changes in cardiovascular system (CVS), and stimulates sympathetic nervous system, which leads to increase of total peripheral resistance (TPR) and acceleration of heart rate (HR). The hemodynamic changes influence pulse wave shape and mechanical properties of the arterial system. Arterial compliance (C) and elastance (Ea) are parameters used to describe mechanical properties of the arterial system. The study aim was to evaluate arterial stiffness by evaluation of arterial elastance and compliance during graded head-up tilting and assessment of the relationship between the change of the tilt angle and those parameters in healthy young subjects.

Material and methods: The study was conducted in 32 healthy volunteers (21-30 years old, 17 female). After 20 minutes of supine rest, the head-up tilting was performed with the use of a tilt-table with electrical engine. The tilt-table was stopped for 1 minute after reaching the angle of 15 degrees and its multiples (i.e. 30, 45, 60, 75 and 90 degrees). Hemodynamic parameters were measured by means of chest bioelectrical impedance method (BioZcom monitor, CardioDynamics, USA). The association of the sine of the tilt angle with Ea and C was calculated with the use of Pearson correlation.

Results: A strong positive correlation between the sine of the tilt angle and Ea was noted (r = 0. 5084; p < 0.0001). A negative correlation between the change of the tilt angle during head-up tilting and C was found (r = -0.4608; p < 0.0001).

Conclusion: During graded head-up tilting, arterial stiffness increases in young healthy people.