OBJECTIVE Arterial hypertension leads to vascular structural and functional adaptive processes that are influenced by angiotensin II. To analyze the effects of AT receptor blockade on vascular function we determined augmentation index. METHODS AND DESIGN A total of 60 patients (53 +/- 10 years) with essential hypertension mean [blood pressure (BP) 173 +/- 9/102 +/- 3 mmHg] were randomized to 6 weeks double-blind therapy with either valsartan 80 mg, hydrochlorothiazide (HCTZ) 25 mg or placebo once daily. Radial artery pressure wave was determined by applanation tonometry before and after therapy. The central aortic pressure wave and augmentation index were derived by a generalized transfer function. RESULTS Active therapy similarly reduced systolic and diastolic blood pressure (SBP, DBP) (valsartan: -22 +/- 18/-11 +/- 11 mmHg, HCTZ: -22 +/- 23/-14 +/- 14 mmHg, all P < 0.001). However, only valsartan, but no HCTZ reduced the augmentation index (valsartan: from 148 +/- 18 to 126 +/- 24, < 0.001; HCTZ: from 145 +/- 19 to 142 +/- 18, NS). Augmentation index reduction was greater with valsartan (-22 +/- 11) than with HCTZ (-3 +/- 11) and placebo (0 +/- 13) (P < 0.01 for pairwise comparison of valsartan versus HCTZ and placebo after Bonferroni correction). Differences remained significant after taking changes in supine BP into account (covariance, P < 0.01). CONCLUSIONS Blood pressure reduction with the AT receptor antagonist valsartan but not with hydrochlorothiazide reduced the augmentation index in essential hypertension.

AT1-receptor blockade improves augmentation index: a double-blind, randomized, controlled study.

This paper proposes an improved DTW algorithm to recognize pulse waveform. Our approach avoids the pathologic alignment that can be caused by original DTW algorithm and DDTW algorithm. Extensive experiments on 1000 pulse waveforms demonstrate the effect of our approach. Compared with original DTW and DDTW algorithms, our algorithm reduces the FRR and FAR greatly. By calculating the similarities between the pulse sample and the five pulse templates, our approach has 92.3% agreement rate with expert.

Recognizing wrist pulse waveforms with improved dynamic time warping algorithm

Long-term and continuous non-invasive blood pressure monitoring has shown that it is the most important to clinical diagnosis of cardiovascular diseases and personal home health care. Currently, there are many preferable non-invasive methods, including optical sensor, pressure-sensitive transducers, and applanation tonometry, to get insight of blood pressure and flow signal detection. However, the operation of traditional monitors is cuff accessories needed, and also the sensing probes needed to exert pressure to the user directly. The measurement procedure is limited by long-term, continuous measurement and also easy to cause discomfort. To improve these issues, the non-pressurized and non-invasive measuring method will become an important innovation improvement. In this paper, the novel nanosecond pulse near-field sensing (NPNS) based screening technology with dual-antenna, which includes radio frequency (RF) pulse transmission and two combined flat antenna connected to transceiver of miniature radar, is proposed to derive relative blood pressure parameters from measured blood flow activity (Pulse Wave Velocity, PWV). A dedicated analysis software is also provided to calculate cardiovascular parameters, including PWV, average systolic time, diastolic and systolic pressure, for clinical and homecare applications. To evaluate the performance, the proposed method was applied on blood pressure measurement at the body site of limbs (brachial and leg). As a result, it shows error of DBP and SBP is 5.18±1.61 and 4.09 ± 1.69 mmHg in average compared with the measurement result from commercial product, and performs the capability of continuous long-term monitoring in real-time.

Using dual-antenna nanosecond pulse near-field sensing technology for non-contact and continuous blood pressure measurement

Pulse Wave Velocity(PWV) is an established measure of arterial stiffness. We present a method of measuring local pulse wave velocity by the use of Magnetic Plethysmograph(MPG) sensors. The design of a Compact Single element MPG (CS-MPG) sensor is presented. The functionality of the sensor is verified by phantom experiments. The utility of this sensor for in-vivo measurements of PWV is also demonstrated. Further, a Dual-element MPG (D-MPG) for evaluation of local PWV is also presented. The error in measurement of PWV using this sensor is characterised experimentally and shown to be within acceptable limits. The ability of this dual element sensor to measure local PWV in-vivo is also demonstrated by trials on volunteers.

Local Pulse Wave Velocity estimation using Magnetic Plethysmograph

Clinically arterial stiffness has shown that it is the most important cause of cardiovascular complications and also an independent risk factor to several cardiovascular diseases. In routine, there are many preferable non-invasive methods, including pressure-sensitive transducers, applanation tonometry, Doppler ultrasound and MRI, to get insight of cardiovascular condition. However, the operation of traditional monitors is relied on professionals' experience, and also the sensing probes needed to exert pressure to the user directly. The measurement procedure is short-term and easy to cause discomfort. To improve the issues of these measuring techniques, the non-contact and non-invasive measuring method will become an important innovation. In this paper, the novel nanosecond pulse near-field sensing (NPNS) based screening technology, which includes radio frequency (RF) pulse transmission and a flat antenna connected to transceiver of miniature radar, is proposed to monitor cardiovascular activity. A dedicated analysis software is also provided to calculate cardiovascular parameters, including PWV, average systolic time, reflection index (RI), heart and heart rate variability (HRV), for clinical applications. To evaluate the performance, the proposed method was applied on aortic pulse measurement at the body site of chest. As a result, it shows 0.92 correlations with the measurement result from commercial product, and performs the capability of continuously long-term monitoring in real-time.

M. Van der Steen

Papers

B046: Increased arterial stiffness assessed by pulse wave analysis in patients with hypercholesterolaemia