Arterial stiffness cut-off value and white matter integrity in the elderly.

OBJECTIVE: Central artery stiffness is a confirmed predictor of cardiovascular health status that has been consistently associated with cognitive dysfunction and dementia. The European Society of Hypertension has established a threshold of arterial stiffness above which a cardiovascular event is likely to occur. However, the threshold at which arterial stiffness alters brain integrity has never been established. METHODS: The aim of this study is to determine the arterial stiffness cut-off value at which there is an impact on the white matter microstructure. This study has been conducted with 53 cognitively elderly without dementia. The integrity of the white matter was assessed using diffusion tensor metrics. Central artery stiffness was evaluated by measuring the carotid-femoral pulse wave velocity (cfPWV). The statistical analyses included 4 regions previously denoted vulnerable to increased central arterial stiffness (the corpus callosum, the internal capsule, the corona radiata and the superior longitudinal fasciculus). RESULTS: The results of this study call into question the threshold value of 10 m/s cfPWV established by the European Society of Hypertension to classify patients in neuro-cardiovascular risk groups. Our results suggest that the cfPWV threshold value would be approximately 8.5 m/s when the microstructure of the white matter is taken as a basis for comparison. CONCLUSIONS: Adjustment of the cfPWV value may be necessary for a more accurate distinction between lower and higher risk group of patients for white matter microstructural injury related to arterial stiffness. Targeting the highest risk group for prevention methods may, in turn, help preserve brain health and cognitive functions.

A novel methodology for rat aortic pulse wave velocity assessment by Doppler ultrasound: validation against invasive measurements.

There is still lack of a simple, accurate, and noninvasive method for rat aortic pulse wave velocity (PWV) measurement, especially the transit distance cannot be accurately measured. Thus, we aimed to derive an equation for aortic transit distance as a function of the nose-to-rump length (L) and to test the hypothesis that aortic PWV measured by new equation combined with Doppler ultrasound (the "equation method") may have stronger correlation with invasive measurements than traditional "body surface method." Two-hundred male Sprague-Dawley (SD) rats (age ranged 5-24 wk) were included in protocol 1, and the aortic transit distances were measured postmortem. In protocol 2, heart-femoral PWV and carotid-femoral PWV were measured by equation method (hfPWVE, cfPWVE) and also by traditional body surface method (hfPWVS, cfPWVS) in another 30 young and 28 old rats. These measurements were then validated against invasively measured hfPWVI and cfPWVI from the same animal. Protocol 1 showed that the heart-femoral transit distance could be calculated by 0.6086 × L - 1.6523, and the carotid-femoral transit distance by 0.4614 × L + 1.8335. In protocol 2, in young rats, the Pearson r between hfPWVE, cfPWVE, hfPWVS, and cfPWVS and their corresponding invasive measurement were 0.8962, 0.8509, 0.8387, and 0.7828, respectively (all P < 0.0001). In the old group, the results were 0.8718, 0.7999, 0.8330, and 0.7112, respectively (all P < 0.0001). The hfPWVE and cfPWVE showed better agreement with hfPWVI and cfPWVI and lower intra- and interobserver variability compared with hfPWVS and cfPWVS in both groups. These findings demonstrate that this novel methodology provides a simple and reliable method for rat noninvasive aortic PWV measurement.NEW & NOTEWORTHY First, when measuring aortic PWV in SD rat models, the heart-femoral transit distance can be estimated by 0.6086 × L - 1.6523, and the carotid-femoral distance transit distance can be estimated by 0.4614 × L + 1.8335, where L (in mm) is nose-to-rump length. Second, this novel methodology for aortic PWV measurement was validated with a closer correlation with the invasive measurements than traditional approach in young and old rats. Third, this study provides a simple and reliable method for rat noninvasive aortic PWV measurement.