MODULE SUPPLEMENT: CARDIOVASCULAR SYSTEM
Functional Changes

The changes we've discussed alter how the heart functions.

As noted earlier, the vascular system, including the heart, becomes less compliant, although this is difficult to measure directly. There is some increase in vascular resistance causing an increase in systolic blood pressure but not much change in diastolic pressure. However, even with this increase, blood pressure should stay within what is currently considered normal limits; it does not mean that hypertension is a normal change with age.

The increase in ventricular wall thickness, which is variable, can lead to increased oxygen demand. This may regress in very late life.

Another change is that there is a decrease in the aortic contribution to the forward flow of blood, and an increase in the pulse wave velocity.

What does this mean and why is it important?

First--aortic contribution to forward flow.

The aorta is strong and elastic; it expands to contain the blood ejected during systole. It then contracts and pushes the blood forward, helping to maintain an even flow throughout the cardiac cycle. As the aorta gets stiffer and less elastic and distensible, it can't expand as well during systole so it can't hold as much blood in reserve. Then it can't contract as well and so it's contribution to forward flow is diminished. This contributes to the widening pulse pressure that is often seen in older adults. Interestingly, a widened pulse pressure is increasingly viewed as an important cardiovascular risk factor.