Abstract
Local pulse-wave velocity (PWV) is an accurate indicator of the degree of arteriosclerosis (stiffness) in an artery, providing a direct characterization of the properties of its wall. Devices currently available for local PWV measurement are mainly based on ultrasound systems and have not yet been generalized to clinical practice since they require high technical expertise and most of them are limited in precision, due to the lack of reliable signal processing methods. The present work describes a new type of probe, based on a double-headed piezoelectric (PZ) sensor. The principle of PWV measurement involves determination of the pulse transit time between the signals acquired simultaneously by both PZs, placed 23 mm apart. The double probe (DP) characterization is accomplished in three main studies, carried out in a dedicated test bench system, capable of reproducing a range of clinically relevant properties of the cardiovascular system. The first study refers to determination of the impulse response (IR) for each PZ sensor, whereas the second one explores the existence of crosstalk between both transducers. In the last one, DP time resolution is inferred from a set of three different algorithms based on (a) the maximum of cross-correlation function, (b) the maximum amplitude detection and (c) the zero-crossing point identification. These values were compared with those obtained by the reference method, which consists of the simultaneous acquisition of pressure waves by means of two pressure sensors. The new probe demonstrates good performance on the test bench system and results show that the signals do not exhibit crosstalk. A good agreement was also verified between the PWV obtained from the DP signals (19.55 +/- 2.02 ms(-1)) and the PWV determined using the reference method (19.26 +/- 0.04 ms(-1)). Although additional studies are still required, this probe seems to be a valid alternative to local PWV stand-alone devices.

Abstract
Local pulse-wave velocity (PWV) is recognized as the simplest and most reproducible process of non-invasively assessing the vascular marker of arterial stiffness that allowing the risk of cardiovascular diseases to be determinate. Devices currently available for local PWV measurement have not yet been generalized to clinical practice since they require high technical expertise and most of them are limited in precision, due to the lack of reliable signal processing methods. This work describes a new type of probes, based on a piezoelectric sensor in different configurations, single probe and double probe. The principle of PWV measurement involves determination of the pulse transit time between the signals acquired simultaneously by both piezoelectric placed 23 mm apart in the same probe. The double probe characterization is accomplished in different studies, carried out in a dedicated test bench system, capable of reproducing a range of clinically relevant properties of the cardiovascular system.

Abstract
This paper envisages showing the potential of innovative non-invasive techniques based on affordable and easily operated instrumentation as well as user-friendly computer aided algorithms in the screening of cardiovascular (CV) diseases. These techniques are based on the assumption that arterial stiffness is currently an important predicator of the CV diseases development and can be assessed by analyzing the arterial pressure waveform (APW). A previously developed PZ based device for non-invasive APW capture is currently under test in clinical environment, using a heterogeneous population constituted by healthy and unhealthy subjects. A dedicated Matlab analysis tool was designed and developed to extract relevant information and further APW analysis. Several recordings of the APW in the same day and in consecutive months are being performed by trained observers, to evaluate its reproducibility. Data mining analysis is subsequently the last task where the Weka 3-6-5 package software is used. The usefulness of developing data mining algorithms for cardiovascular applications can benefit the CV screenings contributing for the early identification of arterial stiffness related patterns.

Abstract
The social and economic impact of cardiovascular diseases and the importance of efficient early diagnostic tools are self-evident. This project finds its motivation in the foreseeable impact that an accurate, non-invasive and easy-to-use instrument for hemodynamic condition assessment could introduce on the diagnosis and follow-up of these diseases. It aims at developing and testing of a microcontroller based signal monitoring device for cardiovascular studies. The advantages of this system show up in decreasing the associated cost, as well as in increasing its functionality, making the necessary human intervention minimal. The algorithmic component of the project will focus on the main hemodynamic issues currently addressed in literature: separating incident from reflected pulse waves (augmentation index), waveform variability and transfer function Although, additional studies are still required to attain clinical validation, this system seems to be a valid, low cost and easy to use alternative to the highly costly devices in the market. © 2011 IEEE.

Abstract
Four optical probes were developed to measure the arterial distension waveform generated by the ventricular contraction and assess clinically relevant information. The pressure wave propagates through the arterial tree and can be measured in the peripheral arteries. The probes make use of two distinct photo-detectors: planar and avalanche photodiodes. Independently, two different light sources were tested: visible and infrared light. Performance of the probes was evaluated in a test setup that simulates the fatty deposits commonly seen in the obese, between skin and the artery. The probes show good overall performance in the test setup with less than 8% root mean square error (RMSE). However, the probes lit with IR sources show better results for the more extreme cases, with a better resolution in the waveform, higher definition of notable points and higher SNR when compared to the visible source signals. In vivo, the IR probes allow easier waveform detection, even more relevant with the increasing of the deposit structures.

Abstract
In this work, we discuss an algorithm that reliable and accurately identifies the prominent points of the cardiac cycle: the systolic peak (SP), reflection point (RP), dicrotic notch, (DN) and dicrotic peak (DP). The prominent point's identifier algorithm (PPIA) action is based on the analysis a number of features of the arterial pressure waveform and its first derivative, and is part of the fundamental software analysis pack for a new piezoelectric probe designed to reproduce the arterial pressure waveform from the pulsatile activity taken non-invasively at the vicinity of a superficial artery. The output PPIA is the coordinates (in time and amplitude) of the above referred points. To assess the accuracy of the algorithm, a reference database of 173 pulses from eight volunteers, was established and the values yielded by the PPIA were compared to annotations from a human expert engineer (HEE). The quality of the results is statistically quantified either in time as in amplitude. Average values of 4.20% for error, 99.09% for sensitivity and 96.77% for positive predictive value were found to be associated to time information while amplitude yields averages of 2.68%, 99.08% and 98.22%, respectively, for the same parameters.