Non-invasive assessment of arterial stiffness by pulse-wave velocity correlates with endothelial dysfunction.

BACKGROUND: Pulse-wave velocity is the speed of the blood pressure wave to travel a given distance between two sites of the arterial system and is determined by the elasticity, wall thickness and blood density. Pulse-wave velocity correlates well with arterial distensibility and stiffness and is a useful non-invasive index to assess arteriosclerosis. Arterial endothelial dysfunction is one of the key early events in atherogenesis, preceding structural atherosclerotic changes. This study sought to establish the correlation of non-invasive estimation of arterial wall stiffness by pulse-wave velocity and its association with endothelial dysfunction in subjects at higher risk for atherosclerosis.

METHODS AND RESULTS: A total of 102 subjects (60 males and 42 females, mean age 51 years), including those with hypertension (n = 39), type 2 diabetes mellitus (n = 26), concomitant type 2 diabetes mellitus and hypertension (n = 29) and primary dyslipidemia without diabetes mellitus and hypertension (n = 8). Pulse-wave velocity was measured by the Vascular Profiler 1000 (VP-1000) waveform analysis and vascular evaluation system, an automated, non-invasive, screening device. Endothelial function was assessed by flow-mediated dilation of the brachial artery. The brachial-artery diameter was measured on B-mode ultrasound images, with the use of a 7.0 MHz linear-array transducer. Mean brachial artery pulse-wave velocity on the right extremity was 1699 cm/s and on the left 1694 cm/s. Mean flow-mediated dilation in the study subjects was 3.6 +/- 8.4%. Mean brachial artery pulse-wave velocity in the right and left extremities and the higher value of brachial artery pulse-wave velocity of the two extremities showed a negative and significant correlation with flow-mediated dilation of the brachial artery (correlation coefficient r = -0.32, p = 0.001; r = -0.40 p < 0.0001; r = -0.37, p = 0.001, respectively). Mean heart-brachial pulse-wave velocity also showed a negative and significant correlation with flow-mediated dilation of the brachial artery (r = -0.23, p = 0.022). Mean arterial stiffness was 36.2 +/- 22%. Arterial stiffness in the right extremity and the higher value of the two extremities showed a negative and significant correlation with flow-mediated dilation of the brachial artery (correlation coefficient r = -0.31, p = 0.002; r = -0.32, p = 0.001, respectively).

CONCLUSIONS: Increased values of pulse-wave velocity reflecting upon arterial stiffness show an excellent correlation with reduced values of brachial artery flow-mediated dilation. We propose that the non-invasive modalities of estimation of the pulse-wave velocity and endothelial function estimation by flow-mediated dilation of brachial artery be used in clinical practice in assessment of pre-clinical atherosclerosis.