272 REVISTA ARGENTINA DE CARDIOLOGÍA / VOL 76 Nº 4 / JULY-AUGUST 2008 BASIC SCIENCES Index of Pressure Wave Reflection Assessed from Radial Pulse Wave Analysis FERNANDO M. CLARA *, 1 , ALFREDO CASARINI **, 2 , ADRIANA G. SCANDURRA *, 3 , GUSTAVO J. MESCHINO *, 4 , ANÍBAL R. INTROZZI *, 5 Key words > Abbreviations > * Laboratory of Bioengineering, Universidad Nacional de Mar del Plata. Mar del Plata, Argentina ** Clínica 25 de Mayo. Mar del Plata, Argentina 1 Telecomunications Engineer. Head Professor - Researcher 2 Medical Doctor specialized in Cardiology 3 Electrical and Electronic Engineer. Head of Practical Assignments - Researcher 4 Electronical Engineer. Assistant Professor of Practical Assignments - Researcher 5 Medical Doctor specialized in Peripheral Vascular Surgery. Associated Professor - Researcher Received: 09/13/2007 Accepted: 05/13/2008 Address for reprints: FERNANDO M. Clara - Rawson 999 (7600) Mar del Plata, Provincia de Buenos Aires e-mail: fmclara@fi.mdp.edu.ar Phone: (0223) 451-1015 ABSTRACT Systolic wave width, a parameter obtained from the record of radial pulse wave, is easier to measure than the radial augmentation index. The aim of this study was to analyze the possibility of using systolic wave width as a complementary tool for the assessment of systolic wave reflection which is directly related to the degree of endothelial dysfunction and to aortic augmentation. We performed a population study on 120 healthy men between 17 and 65 years old with normal blood pressure. Records of the radial wave pulse were obtained, based on the movement of the arterial walls, by a capacitive sensor in contact with the surface of the wrist over the radial artery. Each record was processed and its amplitude was normalized; the augmentation index and systolic wave width at half its maximum height were calculated. We found that systolic wave width was different among subjects with the same augmentation index, showing different values of the amplitude of the reflected wave. Both parameters increased with age (r correlation value 0.9). The systolic wave width is an alternative index of ageing. It might assess the arterial system when it is difficult to meas- ure augmentation index or when comparisons between individuals result ambiguous. REV ARGENT CARDIOL 2008;76:272-277. Arterial pulse - Radial artery - Physiology SWW Systolic wave width SW Systolic pressure wave RAIx Radial augmentation index SR Systolic reflection DW Diastolic wave PS Propagation speed PW Arterial pulse wave BACKGROUND Analysis of the arterial pulse wave (PW) from the record of the radial pulse reveals the existence of a reflection of the systolic pressure wave (SW) in the end arteries. (1) This systolic reflection (SR) occurs during the down slope of the SW from the radial pres- sure record. Figure 1 shows the typical records of a young subject, an adult and an elder. Systolic pres- sure and diastolic pressure are represented in the graph as amplitudes of 100% and 0%, respectively. Basically, in young subjects the SW is narrow and the diastolic wave (DW) is wide. As years go by, the SW expands and the amplitude of the DW decreases. The amplitude of the SR is low in young people and is lo- cated at the bottom of the SW. As age increases, the SR arrives earlier at the recording site as a conse- quence of a rise in the propagation speed (PS) of the pressure wave and in the arterial vasoconstrictor tone; thus the amplitude of the SR increases. In the elder, the amplitude of the SR is great and it appears next to the vertex of a wide SW. (2) The effects of hyper- tension are similar to natural ageing, though they appear in younger persons. (3) The magnitude and the location of the SR reflect the extent of aortic augmentation which is harmful to the left ventricle and the aortic wall. Aortic aug- mentation starts in the ascending aorta and is fre- quent in adults and in the elder with a high propaga- tion speed of the PW that anticipates the arrival of the SR. When SR coincides with the plateau of the aortic SW, the aortic pressure rises. The myocardium is overstrained in order to maintain the systolic vol- ume, and arterial walls are subjected to a greater ten- sion, producing the breakage of elastin fibers in the arterial wall, with the subsequent reduction in aortic