4.1 OverviewThis chapter provides some information on pulse wave analysis and its relation to arterial disease. The arterial pulse waveform is a rising wave that travels forward with the reflected wave. The amount of wave reflection depends on properties of the arterial wall such as arterial stiffness and is expressed in terms of the enhancement index. This approach has been extensively studied using various measurement techniques, each of which has respective advantages and disadvantages. The purpose of the PWA can be seen in the section describing medical conditions that affect the waveform. Discussion is included to help the reader understand the purpose of pulse wave analysis. 4.2 Description of the pulse waveform O'Rourke [13] describes the pulse waveform as: “A sharp upward motion, a straight rise to the first systolic peak and near-exponential decay of pressure in late diastole. " Arteries are compliant structures that buffer the change in pressure resulting from the pumping action of the heart. Arteries function by expanding and absorbing energy during systole (contraction of the heart muscle) and releasing this energy by retracting during diastole (relaxation of the heart muscle ) This feature produces a smooth pulse wave that includes a sharp rise and gradual decay of the wave, as shown in Figure 5. As arteries age, they become less compliant and do not completely buffer the pressure change results in an increase in systolic pressure and a decrease in diastolic pressure.Figure 5: Example of pulse waveform4.3 Wave reflectionIn an arterial system, the input impedance of the vessel varies with changes in size and in the properties of the vase. For compliant arteries, which...... middle of paper ......exsure in the central arteries. • Hypertension: Hypertension is an abnormal increase in systolic, diastolic, or mean blood pressure, or all three. This is due to increased arterial stiffness and can be monitored using PWA• Diabetes mellitus: Diabetes mellitus (type I diabetes and type II diabetes) has been associated with increased arterial stiffness. O'Rourke's studies have shown that PWA does not aid in the diagnosis of diabetes mellitus. Further research by Cruickshank demonstrated that PWV is a powerful independent predictor of diabetes mortality. • Chronic renal failure: Savage et al conducted an investigation of the reproducibility of PWA in patients with chronic renal failure (CKD). Their study concluded that indices of arterial stiffness, such as AiX and Time to Reflection (TR), determined by PWA, can aid in the assessment of CRF