Superiority of 24-Hour Aortic Over 24-Hour Brachial Pressure to Associate With Carotid Arterial Damage on the Basis of Pressure Amplification Variability: the SAFAR Study

Background: Evidence suggests marginal superiority of static aortic systolic blood pressure (aSBP) compared with brachial SBP regarding the association with organ damage and prognosis of cardiovascular disease. The noninvasive 24-hour aSBP assessment is feasible and associates better with presence of left ventricular hypertrophy compared with 24-hour brachial systolic blood pressure. We aimed at comparing the association of 24-hour aSBP and 24-hour brachial systolic blood pressure with indices of arterial damage and examining the role of 24-hour SBP amplification variability (within-subjects’ SD) in this association. Methods: Consecutive subjects referred for cardiovascular disease risk assessment underwent 24-hour aortic and brachial ambulatory BP monitoring using a validated oscillometric device (Mobil-O-Graph). Arterial damage was assessed by carotid intima-media thickness and detection of carotid and femoral atheromatosis (plaque presence). Results: Cross-sectionally 501 individuals (aged 54±13 years, 57% men, 80% hypertensives) were examined. Multivariable analysis revealed superiority of 24-hour aSBP regarding the association with intimal-medial thickness, carotid hypertrophy and carotid—but not femoral—atheromatosis. In receiver operator characteristics analysis, 24-hour aBP displayed a higher discriminatory ability—compared to 24-hour brachial systolic blood pressure—for the detection of both carotid hypertrophy (area under the curve, 0.662 versus 0.624, P <0.05) and carotid atheromatosis (area under the curve, 0.573 versus 0.547, P <0.05). This effect was more prominent in individuals with above-median 24-hour SD of SBP amplification. Conclusions: Our results suggest that 24-hour aSBP assessment may be of significant value in clinical practice to detect site-specific arterial damage on the basis of pressure amplification variability and should be prospectively examined in clinical trials.

Evaluating a Human Ear-Inspired Sound Pressure Amplification Structure with Fabry–Perot Acoustic Sensor Using Graphene Diaphragm

In order to enhance the sensitivity of a Fabry–Perot (F-P) acoustic sensor without the need of fabricating complicated structures of the acoustic-sensitive diaphragm, a mini-type external sound pressure amplification structure (SPAS) with double 10 μm thickness E-shaped diaphragms of different sizes interconnected with a 5 mm length tapered circular rod was developed based on the acoustic sensitive mechanism of the ossicular chain in the human middle ear. The influence of thickness and Young’s modulus of the two diaphragms with the diameters of 15 mm and 3 mm, respectively, on the amplification ratio and frequency response were investigated via COMSOL acoustic field simulation, thereby confirming the dominated effect. Then, three kinds of dual-diaphragm schemes relating to steel and thermoplastic polyurethanes (TPU) materials were introduced to fabricate the corresponding SPASs. The acoustic test showed that the first scheme achieved a high resonant response frequency with lower acoustic amplification due to strong equivalent stiffness; in contrast, the second scheme offered a high acoustic amplification but reduced frequency range. As a result of sensitivity enhancement, adapted with the steel/TPU diaphragm structure, an optical fiber Fabry–Perot sensor using a multilayer graphene diaphragm with a diameter of 125 μm demonstrated a remarkable sensitivity of 565.3 mV/Pa @1.2 kHz due to the amplification ratio of up to ~29.9 in the range of 0.2–2.3 kHz, which can be further improved by miniaturizing structure dimension, along with the use of microstructure packaging technology.