Short-Term Arterial Compliance Changes in the Context of Systolic Blood Pressure Influence

Abstract

Arterial compliance (C) is a complex parameter influencing ventricular-arterial coupling depending on structural (arterial wall remodeling) and functional (blood pressure, smooth muscles tone) changes. Based on Windkessel model, C can be calculated as the ratio of a time constant Tau characterizing diastolic blood pressure decay and total peripheral resistance (TPR). The aim of this study was to assess changes of C in the context of systolic arterial pressure (SAP) perturbations during four physiological states (supine rest, head-up tilt, supine recovery, mental arithmetic). In order to compare pressure independent changes of C a new index of C120 was proposed predicting C value at 120 mm Hg of SAP. Eighty-one healthy young subjects (48 f, average age 18.6 years) were examined. Hemodynamic parameters were measured beat-to-beat using volume-clamp photoplethysmographic method and impedance cardiography. We observed that C was strongly related to SAP values on the beat-to-beat time scale. Interestingly, C120 decreased significantly during stress phases. In conclusion, potential changes of SAP should be considered when measuring C. Arterial compliance changes in the opposite direction to TPR pointing towards influence of vascular tone changes on its value.

Spectral analysis of the beat-to-beat variability of arterial compliance

“…Our results document that orthostasis challenges arterial compliance by causing a significant decrease of its mean values and variability (Table 1). This is in accordance with previous findings [3], [6] and suggests that, when higher sympathetic activity is assumed, the well-known changes of heart rate and total peripheral resistance via fast baroreflex mechanisms occurs together with a concomitant increase of arterial stiffness. Furthermore, it was demonstrated that vasomotion has an important influence on the arterial compliance [3].…”

“…This is in accordance with previous findings [3], [6] and suggests that, when higher sympathetic activity is assumed, the well-known changes of heart rate and total peripheral resistance via fast baroreflex mechanisms occurs together with a concomitant increase of arterial stiffness. Furthermore, it was demonstrated that vasomotion has an important influence on the arterial compliance [3]. The significant increase of LF and the decrease of HF power with tilt (Fig.…”

“…The arterial compliance time series analyzed in this study are taken from a larger database recently collected [3]. Stationary segments of 300 consecutive beats were extracted from the original recordings in the resting supine position (REST) and in the upright position reached after passive head-up tilt (TILT).…”

“…In this work, only 39 subjects were selected for further analysis after visual inspection of the time series. We refer the reader to [3] for further information about the database.…”

“…To fill this gap, the present study aims at investigating the short-term variability of arterial compliance in both time and frequency domains. To this end, beat-to-beat time series of C measured in young healthy subjects undergoing a head-up tilt procedure using a recently developed noninvasive methodology [3] were analyzed computing standard time domain parameters as well as frequency-domain measures derived from the method of spectral decomposition [4], [5]. In particular, the use of spectral decomposition allows to retrieve the power content associated to specific oscillations with central frequency in the low frequency (LF, 0.04 − 0.15 Hz) and high frequency (HF, 0.15 − 0.4 Hz) bands of the spectrum.…”