Characterization of a double probe for local pulse wave velocity assessment

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.

Photoplethysmographic logger with contact force and hydrostatic pressure monitoring

“…It will consist of a multichannel systems that incorporate some conventional sensors (including pulse oximetry and photoplethysmography) allied with pioneer sensors developed at the group [12][13][14][15].…”

New instrumentation for cardiovascular risk assessment: The role of pulse wave velocity

“…The probe's mechanical interface consists of two mushroomshaped PVC pieces, located in the centre of the PZ discs. These elements are responsible for transmitting the distension imparted to tissues by the pressure waveform, to each PZ sensor [10]. …”

“…Through deconvolution principle, it was possible to recover the (input) pressure waveform. More details about these two issues can be found in [10] and [11]. Figure 5 concerns test bench characterization and it depicts the propagation of a Gaussian pressure wave (50ms width) along the silicone tube.…”

Comparison of Low-Cost and Noninvasive Optical Sensors for Cardiovascular Monitoring

“…This is hard to achieve, since the sensor has to be correctly placed to obtain zero stress of the artery and no deformational stress, which turns applanation tonometry an operator mastery dependent technique [6]. In the last years, piezoelectric based probes have been widely used in arterial pressure waveform assessments, which generate a measurable voltage at the output contacts if they are mechanically deformed [7], [8], and [9]. The photoplethysmography is another available solution, based on the transmission of the infrared light produced by a light emitting diode (LED) through a finger or earlobe, which is detected by a photodetector, producing an attenuation profile volume waveform from which changes in volume can be measured.…”