Aim: To investigate the distensibility of the common carotid artery (CCA), baroreflex sensitivity (BRS) and its relation to plasma homocysteine concentration in exfoliation syndrome or exfoliation glaucoma (XFS/XFG). Methods: Homocysteine concentrations were measured in 30 XFS/XFG patients and 18 age matched controls. In 21 patients and 17 controls the end diastolic diameter of the CCA and pulsatile distension were measured and BRS was calculated.Results: There was no significant difference between the groups in sex distribution, age, heart rate, blood pressure, systemic diseases, or medication. In XFS/XFG patients homocysteine concentration was significantly elevated (unpaired t test, p = 0.023), and CCA stiffness was higher (p,0.05), while strain, cross sectional compliance coefficient, distensibility, and BRS were significantly reduced compared to the controls (Mann-Whitney U test, p(0.013 for each parameter). In XFS/XFG patients a positive correlation was found between age and plasma homocysteine level (Pearson's correlation, r = 0.490, p = 0.007), and a negative correlation between age and BRS (Kendall's correlation r = 20.374, p = 0.021), as well as between homocysteine concentration and BRS (Kendall's correlation r = 20.377, p = 0.024). No correlation was seen between these variables in the control group. Conclusions: These results suggest a pathological large artery function as well as altered parasympathetic vascular control in XFS/XFG which increases with age and with higher homocysteine concentration.

Stiffening of the carotid artery significantly contributes to the impairment of baroreflex sensitivity during pregnancy, and represents a region specific change as global arterial distensibility was found to increase during pregnancy.

In clinical studies, the elastic behavior of central arteries is usually assessed by measuring dynamic distensibility. In this study, we aimed to investigate how dynamic and static distensibility of the common carotid artery (D_dyn and D_stat, respectively) are related in 28 healthy volunteers of 20–71 years. The carotid diameter and its change with the pressure pulse were measured using an ultrasound echo-tracking device. Arterial blood pressure was measured by Finapres and carotid pressure was determined by applanation tonometry. D_dyn was determined at rest using the pressure pulse, while D_stat was determined during pressor responses induced by handgrip or cold pressor test. Data are given as mean ± 1 SD. In younger subjects (<35 years), D_stat did not differ from D_dyn (7.0 ± 3.4 vs. 6.5 ± 2.1·10^–3·mm Hg^–1, respectively), whereas in older subjects (>35 years), D_stat was significantly higher than D_dyn (3.8 ± 1.4 vs. 2.1 ± 0.9· 10^–3·mm Hg^–1, p < 0.001). For all subjects, D_stat and D_dyn decreased with increasing age and mean arterial pressure (MAP). Using stepwise multiple regression analysis, the strongest predictor of D_stat proved to be MAP, while that of D_dyn was age. D_stat was found to be linearly related to the hysteresis loop area of the pressure-diameter relation (r = 0.94), i.e. to vessel wall viscosity. It is concluded that, with increasing age, static distensibility overestimates the distension capacity of large arteries.

Stiffening of the barosensory vessel wall in hypertension has been suggested to play a role in the associated baroreflex impairment. The carotid distensibility-BRS (baroreflex sensitivity) relationship, however, has not been studied in pre-eclampsia, a condition where hypertension is spontaneously reversible. Twelve normotensive pregnant women and 12 patients with pre-eclampsia matched for maternal age and week of gestation were studied in the third trimester and 3 months postpartum. Carotid artery diastolic diameter and pulsatile distension was measured by echo-wall tracking and carotid pulse pressure by applanation tonometry, and the carotid distensibility coefficient was calculated. Spontaneous BRS was determined by the sequence and spectral methods from 10 min continuous recording of ECG and finger arterial blood pressure. In the third trimester, carotid distensibility was lower in patients with pre-eclampsia than in normotensive pregnant women (2.47+/-0.17 compared with 4.08+/-0.16 x 10(-3)/mmHg); postpartum, it increased moderately in patients, but remained below normotensive values (3.25+/-0.12 compared with 4.25+/-0.19 x 10(-3)/mmHg). In the third trimester, both patients and healthy pregnant women had equally low BRS values; postpartum, the various BRS indices increased markedly (by 60-190%) and to the same level in both groups. No correlation was found between changes in carotid artery distensibility and those in BRS from the third trimester to postpartum period in patients and healthy pregnant women. The lack of association between changes in carotid distensibility and BRS suggest that stiffening of the carotid artery in pre-eclampsia is not responsible for baroreflex dysfunction.

Our results suggest that in patients with chronic open-angle glaucoma the arterial rigidity is significantly increased and therefore the baroreflex function is significantly decreased. These findings may have relevance in the understanding of the autonomic dysfunction and vascular dysregulation in glaucoma.