Abstract-Central-to-peripheral amplification of the pressure pulse leads to discrepancies between central and brachial blood pressures. This amplification depends on an individual's hemodynamic and (patho)physiological characteristics. The aim of this study was to assess the magnitude and correlates of central-to-peripheral amplification in the upper limb in a healthy, middle-aged population (the Asklepios Study). Carotid, brachial, and radial pressure waveforms were acquired noninvasively using applanation tonometry in 1873 subjects (895 women) aged 35 to 55 years. Carotid, brachial, and radial pulse pressures were calculated, as well as the absolute and relative (with carotid pulse pressure as reference) amplifications. With subjects classified per semidecade of age, carotid-to-radial amplification varied from Ϸ25% in the youngest men to 8% in the oldest women. Amplification was higher in men (20Ϯ14%) than in women (13Ϯ12%; PϽ0.001) and decreased with age (PϽ0.001) in both. Amplification over the brachial-to-radial path contributed substantially to the total amplification. In univariate analysis, the strongest correlation was found with the carotid augmentation index (Ϫ0.51 in women; Ϫ0.47 in men; both PϽ0.001). In a multiple linear regression model with carotid-to-radial amplification as the dependent variable, carotid augmentation index, total arterial compliance, and heart rate were identified as the 3 major determinants of upper limb pressure amplification (R 2 ϭ0.36). We conclude that, in healthy middle-aged subjects, the central-to-radial amplification of the pressure pulse is substantial. Amplification is higher in men than in women, decreases with age, and is primarily associated with the carotid augmentation index. Key Words: cardiovascular physiology Ⅲ blood pressure Ⅲ large arteries Ⅲ wave reflection Ⅲ hemodynamics I t has long been demonstrated that, when the blood pressure waveform is measured along the arterial tree, it changes continuously in shape and amplitude. 1,2 In large-and medium-sized arteries, the systolic upstroke of the wave generally becomes steeper from the central aorta toward the periphery, whereas the amplitude also increases, mainly through an increase in the peak value (systolic blood pressure) of the waveform. Overall, the minimum (diastolic) and mean (mean blood pressure) values, and especially the difference between both, change little from one location to the other. 3 These are well-known features described in physiological textbooks, and these phenomena can be explained on the basis of wave travel and reflection. The heart generates a forward-running pressure wave, which is reflected in the periphery. The measured pressure at any location is, thus, composed of this forward component, as well as backward components, arising from reflections. 4,5 The closer the blood pressure is measured to the reflection site (ie, the further in the periphery), the earlier the forward and backward waves will interact, leading to the steeper systolic upstroke and the more peaked appearance o...

Both carotid artery SBP and central SBP obtained via a transfer function are highly sensitive to the calibration of the respective carotid artery and radial artery pressure waveforms. Our data suggest that the one-third rule to calculate MAP from brachial cuff BP should be avoided, especially when used to calibrate radial artery pressure waveforms for subsequent application of a pressure transfer function. Until more precise estimation methods become available, it is advisable to use 40% of brachial pulse pressure instead of 33% to assess MAP.

No abstract

The tape measure distance from CA-FA, multiplied by 0.8, corresponds best with the real travelled aortic path length. This distance is moderately (yet statistically significantly) influenced by age and minimally by BMI.