Aortic Pulse Wave Velocity (PWVao)
The most frequently used parameter in the medical scientific literature for describing arterial stiffness is pulse wave velocity (PWV). PWV is mainly related to aortic wall characteristic. Basically, the more rigid the aortic wall, the faster the aortic PWV.
Aortic Pulse Wave Velocity (PWVao) is an independent predictor of coronary heart disease and stroke in asymptomatic, apparently healthy subjects and it is a strong indicator for cardiovascular risk and used increasingly in clinical practise. Moreover, it is also related to the sub-clinical coronary atherosclerosis independently from conventional risk factors, including blood pressure indices.
Pulse Wave Velocity Test
Measurement of PWVao provides some of the strongest evidence concerning the prognostic significance of large artery stiffening. Furthermore, increased PWVao has been shown to predict cardiovascular, and in some cases all cause, mortality in individuals with end stage kidney disease, hypertension, diabetes mellitus and in the general population. In fact, Aortic Pulse Wave Velocity is the velocity at which blood pressure pulse propagates in the aorta and it is used clinically as a measure of arterial stiffness and can be measured non-invasively by Arteriograph.
Arteriograph is equipped with an inflatable cuff placed on the patient’s upper arm and inflated 45 mmHg above the individual’s Systolic Blood Pressure (SBP). Pressure variations are detected by a pressure sensor and signal is transferred to a computer. PWV acquirement is based on the generation of two systolic peaks: the first peak (P1) results from the systolic volume ejection in the aorta, whereas the second and lower peak P2 is given by wave pressure reflection from peripheral arteries. Return time is the difference between the first peak (P1) and the reflected systolic peak (P2). PWV is calculated as shown:
PWV = S (Jug-Sy)/(RT/2)
Distance (S) is measured from jugular (Jug) to symphysis (Sy), RT: return time
This parameter predicts future cardiovascular events and all-cause mortality independent of conventional cardiovascular risk factors. Increased values of PWVao are related to elevated cardiovascular risk and atherosclerotic organ damage. Vascular age assessment is based on the values of it. Pulse Wave Velocity varies with blood pressure, and it increases with pressure. Higher systolic blood pressure and/or heart rate can increase values of aortic Pulse Wave Velocity causing enhanced lateral tension (i.e. stiffness) on the aortic wall and can lead false arterial age assessment
What is Normal Pulse Wave Velocity?
To begin with, by advancing age, PWV could be increased. But, several studies show that PWVao is normal under 9 m/s. It should be noted, most of the current devices in the market (except Arteriograph) measure other form of PWV which are criticised by different literature. The most reliable form of PWV measurement is aortic one.