Tham khảo tài liệu 'new developments in biomedical engineering 2011 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 392 New Developments in Biomedical Engineering monitoring. However the only available technique for measuring arterial stiffness non-invasively so far is the so-called Pulse Wave Velocity PWV . In this chapter we will see that the state of the art in PWV assessment is not compatible with the requirements of ambulatory monitoring. The goal of our work is thus to examine the limitations of the current techniques and to explore the introduction of new approaches that might allow PWV to be established as the new gold-standard of vascular health in ambulatory monitoring. This chapter is organized as follows in Section 2 we introduce the phenomenon of pulse propagation through the arterial tree. In section 3 we provide a large review on the clinical relevance of aortic stiffness and its surrogate PWV. In Section 4 we perform an updated analysis of the currently existing techniques available for the non-invasive assessment of PWV. Section 5 describes a novel approach to the measurement of PWV based on a non-obtrusive and unsupervised beat-to-beat detection of pressure pulses at the sternum. Finally Section 6 reviews the historic and current trends on the use of PWV as a non-obtrusive surrogate for arterial blood pressure. 2. The genesis and propagation of pressure pulses in the arterial tree In cardiovascular research and clinical practice PWV refers to the velocity of a pressure pulse that propagates through the arterial tree. In particular we are interested in those pressure pulses generated during left ventricular ejection at the opening of the aortic valve the sudden rise of aortic pressure is absorbed by the elastic aorta walls. Subsequently a pulse wave naturally propagates along the aorta exchanging energy between the aortic wall and the aortic blood flow Figure 1 . At each arterial bifurcation a fraction of the energy is transmitted to the following arteries while a portion is reflected backwards. Note that one can easily palpate the arrival of arterial pressure .
