Background: We recently reported that central blood pressure (BP) obtained non-invasively in chronic kidney disease (CKD) patients significantly underestimated the central BP with decreasing eGFR in ...comparison with invasively measured true central BP in the aorta. This post-hoc analysis investigated whether the presence of aortic calcification affected non-invasive estimates of central BP. Methods: CKD stage 4–5 patients undergoing coronary angiography were included. Invasive aortic BP was measured through angiography catheters. Non-invasive central BP was obtained with the SphygmoCor device. Calcium score (CS) in the aorta was quantified using CT. Results: Twenty-four patients were enrolled (meanSD): 63% males, age 53±11 years, and eGFR 95 ml/min/1.73 m2. Invasive aortic SBP was 152±23 mmHg. Estimated central SBP was 133±20 mmHg. Ten patients had a CS=0 in both ascending and descending aorta, 2 patients had ascending aortic CS>0 while 8 patients had descending aortic CS>0 and 4 patients had both ascending and descending aortic CS>0. In patients with CS>0 in the descending aorta, central SBP was underestimated by 4(117) mmHg (P=0.02) compared to patients with CS=0. No significant difference was found between patients with and without calcium in the ascending aorta (P=0.13). In patients with CS>0 in both descending and ascending aorta central SBP was underestimated by 14(326) mmHg (P=0.02) compared to patients with CS=0 in both segments. Conclusion: In advanced CKD, aortic calcification significantly affected the difference between estimated and invasively measured central BP. This may question the usefulness of non-invasive estimates of central BP in high-risk patients with severe aortic calcification.
In this paper we present a refined model of the wireless multipath channel along with a thorough analysis on the impact of spatial smoothing techniques when used for improved channel estimation. The ...state-of-the-art channel estimation algorithm for pilot-aided OFDM systems is robustly designed and operates without knowledge of the time-varying multipath propagation delays in the wireless channel. However, algorithms exploiting knowledge of these time-varying delay parameters can outperform the state-of-the-art solution. We demonstrate from simulations how the Unitary ESPRIT algorithm together with spatial smoothing techniques exhibit a promising potential for multipath propagation delay estimation. Furthermore, we show that the optimum smoothing parameters depend notably on the channel model assumed, specifically in terms of the dynamical behavior of the multipath delays.
A total of 60 attendees at a medical conference had their peripheral and central blood pressure measured before and after the conference dinner. While heart rate increased, all measurements of ...peripheral and central blood pressure showed lower values after dinner. Furthermore, attendees' central vascular age was reduced by 13 years after dinner when augmentation index was evaluated in relation to age. Although 13% experienced postprandial hypotension, the present study motivates attendance at medical conference dinners due to the health implications of lowered blood pressure.
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