Applanation tonometry for evaluation of the haemodynamic response to the active orthostatic test

Abstract

Background: Our study was aimed at the assessment of the age-specific hemodynamic response to the active orthostatic test (OT). Methods: Two groups (60-Y/O and 20-Y/O) were subjected to OT (three 5-minute periods: baseline supine, upright standing, recovery supine). Continuous electrocardiogram was recorded and heart rate variability (HRV) analysed. At the end of each period pulse wave analysis was performed (Sphygmocor, AtCor Medical). Results: We observed significantly higher radial and central systolic and pulse pressures in the adults at baseline. We found out reduced efficiency of the hemodynamic compensatory response to orthostasis in the 60-Y/O group: mild heart rate increase (75 ± 2 vs. 88 ± 3 beats per minute); moderate aortic systolic pressure reduction (124 ± 6 to 119 ± 5 vs. 99 ± 2 to 101 ± 3 mm Hg); considerable aortic pulse pressure decrease (47 ± 4 to 38 ± 3 vs. 27 ± 2 to 22 ± 2 mm Hg); absence of diastolic pressure elevation. The adults showed significantly higher baseline augmentation indices (AIx); the young responded to the upright position with noticeable reduction of AIx most probably resulting from the pronounced tachycardia and the consequent delayed timing of pulse wave return. HRV data showed milder sympathetic activation in the 60-Y/O individuals in response to OT as compared to the 20-Y/O. Conclusions: Pulse wave analysis provided new knowledge concerning the age-related hemodynamic response pattern to active orthostasis. We believe the underlying mechanism was the ‘physiological’ arterial stiffening with aging and the ensuing reduced arterial baroreflex sensitivity. HRV data for lesser sympathetic activation in response to the orthostatic challenge in the 60-Y/O group supported this assumption.

Keywords

• Arterial stiffness
• Pulse wave analysis
• Active orthostatic test
• Augmentation index
• Heart rate variability