Arterial stiffness Assessment of arterial stiffness was performed by a noninvasive technique using the commercially available SphygmoCor System (AtCor Medical LTD, Australia). All measurements were performed while the patient was in a recumbent position at room temperature of 25۫ C, between 06:30 and 08:30 A.M. after an overnight fasting (8-10 hours) and after a short period of rest. Peripheral pressure waveforms were recorded from the radial artery at the wrist, using applanation tonometry with a high fidelity micromanometer. When sequential waveforms were recorded, a validated 16-18 generalized transfer function was applied to generate the corresponding central pressure waveform. The integral system software was used to calculate an average radial artery waveform and to derive a corresponding central aortic pressure waveform using a previously validated generalized transfer function. From these data the indexes of arterial stiffness were obtained. The augmentation of central arterial pressure is the difference between the first and second systolic peaks of the central pressure waveforms, and the central augmentation index (AIx) is the augmentation expressed as a percentage of the pulse pressure.