Age-related changes in pulse wave contours and their effect on blood pressure

The shape of the arterial pulse changes with age. When you are young and your arteries are flexible, the wave reflection is much slower. Therefore, in younger people it is normal for the wave reflection to return to the heart after the aortic valve has closed. This amplifies diastolic pressure and facilitates blood flow to the coronary arteries.

However, as we age and the arteries stiffen and become less flexible, everything speeds up. The velocity of both the initial pulse wave and the subsequent wave reflection increases. This means that the wave reflection can get back to its point of origin before the aortic valve closes. The effect of this is to produce a marked increase in systolic blood pressure along with a decrease in diastolic pressure blood pressure.

It also means that the wave reflection’s contribution to the filling of the coronary arteries decreases too. These changes can have significant clinical implications in terms of coronary artery blood flow and can contribute to an increase in systolic blood pressure.

Just like PWV, SI varies with age - the older we get, the stiffer our arteries become. Typical values for a healthy subject, in his twenties should be between 5 and 8 m/s. This changes to between 6 and 10m/s for a healthy sixty year old.

The following values provide a general guide to SI:

Arterial stiffness is expected to rise with aging, in other words it would be typical to have an increase in arterial stiffness as we age. As this chart highlights published by Millasseau et al in Clinical Science in 2002. However whilst the average increases you can see that there are people in upper and lower stiffness limits at many different ages, thus it is possible to have poor arteries in younger years and good arteries in older years.

The “trick” of course is to know where you stand and take steps/ measures in the forms of lifestyle, diet, exercise and supplements to improve your condition. BioClip offers you the possibility not only to know your condition, but also to monitor your improvements to see what is working for you.

The following wave forms are typical for each age group. Generally speaking the more pyramid shaped the wave the worse the result, as this indicates a return/ reflected wave that is very similar/ same as the outbound speed from the heart, hence very hard arteries. You can see from the forms below that the younger/ healthier patients have wave forms that look more like camels (two distinct humps) which is indicative of softer arteries as there is a much more pronounced difference between the measured outbound and inbound speeds.

The PPT refers to “point to point time” or the time between the outbound peak of blood from the heart and the inbound reflected wave from the arteries. The longer the time (hence the slower the wave) the better the result. This you can see in the waves below with the 60-year old having a PPT of 147 milliseconds and 29 year old having a PPT of 346 milliseconds. The simplest way to think about it is like this: If you through a stone into the middle of a pond you see a wave ripple out towards the bank, that ripple has a specific speed. When it hits the bank another smaller ripple is returned, but the speed of that return ripple is dependent upon the hardness of the pond wall. For example, if the pond had a hard concrete wall then little of the energy would have been absorbed and thus a fast return wave would be produced. On the other hand, if the pond had a soft muddy wall, then much of the energy is absorbed and hence a slow wave is returned. It is this same principle that determines the difference between a hard and a soft artery- slow return waves (hence higher PPT results) are better!

Note: In rare cases a third wave can also be visualised, this indicates very soft arteries and is normally only seen in teenagers or atheletes.