BLOOD PRESSURE
“The heart is a tough organ: a marvelous mechanism that, mostly without repairs, will give valiant pumping service up to a hundred years.” ~ Willis John Potts MD. American Surgeon, 1895-1968
Part 2 of the journey
The heart pumps blood to the aorta and the pressure spreading from the walls of the heart travels to the aorta. This pressure continues to travel along the aorta’s walls in wave after wave until it reaches the walls of the smaller branching arteries that take the blood to the rest of the body. There, the speed of these pressure waves – known as pulse wave velocity – slows, and some are sent back through the aorta walls, becoming what are called wave reflections.
Imagine dropping a pebble into a still pond and the ripples that it creates. When the ripples hit something, then they bounce back.
As the walls of the aorta become stiffer, the pressure waves move more rapidly and, as a result, the wave reflection occurs sooner than they did before. The timing of the wave reflection, in fact, is one of the effects of arterial stiffness that can be measured non-invasively.
The reflecting wave is a key component of the CASP test
When we talk about blood pressure, what we are actually referring to is the pressure within the aorta and the large arteries that connect to it.
Blood pressure is measured in millimeters of mercury (mmHg) and recorded as 2 numbers: systolic blood pressure is the maximum pressure that occurs in the blood vessels when the heart contracts, and diastolic pressure which is the low pressure as the heart relaxes between beats.
As the walls of the large arteries become stiffer, diastolic blood pressure tends to drop and systolic blood pressure rises. Arterial stiffening and thickening contribute to increased pulse pressure. Imagine using a water hose and placing a finger over the opening: the pressure builds up.
Many studies have found that elevated pulse pressure is also an important risk factor for stroke and heart attack.
The age-related stiffening impedes blood flow from the heart and places an increased workload on the heart.