Objectives: in this study we address the relationship between spontaneous baroreflex sensitivity and carotid mechanical properties in a clinical setting. Methods: Spontaneous indices of baroreflex regulation are obtained from normal volunteers non-invasively in the time (Baroreflex Slope) and frequency domains ( index and SAP-RR transfer Gain) as well as using an exogenous autoregressive causal model (A.XAR); carotid mechanical properties are approximated using advanced ultrasound coupled with arterial pressure measures. Multivariate analysis and linear modeling provide an estimate of the link between mechanical measures and spontaneous baroreflex indices. Results: subjects are divided in five age groups (from 20 to 60 yrs, mean 44±13). Spontaneous baroreflex indices are reduced with advancing age (BRS from 31.2 to 16.3; index from 27.4 to 13.6; RR-SAP Gain at HF from 31±3.0 to 14±3.0 msec/mmHg all P<<0.001); carotid intima media thickness (IMT: from 0.53 to 0.69 mm; p<<0.001) and local Pulse Wave Velocity (PWV: from 4.0 to 6.9 m/sec) increase with age (both p<<0.001). A significant correlation is present between spontaneous indices of baroreflex sensitivity and carotid mechanical properties, particularly PWV (r = -0.328, p<<0.001). After correcting for age and gender, a significant correlation remains between RR-SAP gain and PWV and between A.XAR and IMT. Factor analysis and automatic linear modeling corroborates the notion that mechanical carotid properties are strong predictors of the age-related reduction of spontaneous baroreflex. Conclusions: a significant correlation between spontaneous baroreflex indices and local carotid mechanical properties supports the idea that they should also be factored in the physiology of baroreflex regulation.
Relationship between carotid artery mechanics and the spontaneous baroreflex: a non invasive investigation in normal humans
2012-01-01
Abstract
Objectives: in this study we address the relationship between spontaneous baroreflex sensitivity and carotid mechanical properties in a clinical setting. Methods: Spontaneous indices of baroreflex regulation are obtained from normal volunteers non-invasively in the time (Baroreflex Slope) and frequency domains ( index and SAP-RR transfer Gain) as well as using an exogenous autoregressive causal model (A.XAR); carotid mechanical properties are approximated using advanced ultrasound coupled with arterial pressure measures. Multivariate analysis and linear modeling provide an estimate of the link between mechanical measures and spontaneous baroreflex indices. Results: subjects are divided in five age groups (from 20 to 60 yrs, mean 44±13). Spontaneous baroreflex indices are reduced with advancing age (BRS from 31.2 to 16.3; index from 27.4 to 13.6; RR-SAP Gain at HF from 31±3.0 to 14±3.0 msec/mmHg all P<<0.001); carotid intima media thickness (IMT: from 0.53 to 0.69 mm; p<<0.001) and local Pulse Wave Velocity (PWV: from 4.0 to 6.9 m/sec) increase with age (both p<<0.001). A significant correlation is present between spontaneous indices of baroreflex sensitivity and carotid mechanical properties, particularly PWV (r = -0.328, p<<0.001). After correcting for age and gender, a significant correlation remains between RR-SAP gain and PWV and between A.XAR and IMT. Factor analysis and automatic linear modeling corroborates the notion that mechanical carotid properties are strong predictors of the age-related reduction of spontaneous baroreflex. Conclusions: a significant correlation between spontaneous baroreflex indices and local carotid mechanical properties supports the idea that they should also be factored in the physiology of baroreflex regulation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
