Arterial Stiffness for beginners

Some evidence:

 
A - The pulse wave velocity (PWV) is the best surrogate for arterial stiffness.

Arterial stiffness is an independent risk factor correlated with cardiovascular morbidity and mortality better than conventional risk factors (i.e. hypertension, high cholesterol, diabetes, tobacco)

It plays a role in the early detection, prevention, management, and prognosis of patients at risk

 

B - It is important to distinguish between pulse wave and blood flow. Blood flows at 0.25 m / s, while the pulse wave propagates at 5-16 m / s.

 

C - The pulse waves propagate like the waves on the surface of a pool of water where you throw a pebble, there are three phenomena:

1 - you can hear the pebble drop in water
2 - The wave on the surface distorts the surface of the water: the water molecules do not move, there is resonance, or shock.
3 - Water moves under the stone that fell into the water generating flow.

 

D - The "blow of the ram": refers to the sound of water in the pipes of old houses: when you close the faucet violently, the shock of the flow of water against the closed valve causes a back wave which resonates upstream.

In the past, it could lead to a rupture in the piping system.

Nowadays we install plastic pipes that absorb the shock waves, hence the sudden disappearance of this phenomenon from houses. In addition we install a "flexible" before every tap in order to protect against this shock.

Similarly, the arrival of the pulse wave in a stiffen arteries cause serious damage in the small arteries.

E - The glass bottle of orange juice: If you struggle to twist off the lid, hit the bottom of the bottle: the result is a pulse wave large enough for the lid to come unstuck and open easily.

Imagine this effect on stiff arteries.

If the bottle were made of softer material, the shock would not have caused the detachment of the lid; the blow would have been absorbed by the container.

The propagation of the wave is dependent on the viscoelastic properties of the medium in which it operates.
The more artery is stiff, the quicker the wave propagates.

F - The Balloon: When you blow a balloon, its wall becomes more stiff ! one more evidence ...
 

G - Indians and trains: Indians used to put their ears to the ground to hear the vibrations of the train. They knew that waves travel faster when the medium is dense! By the time they could hear the train coming, it was already too late to prepare an attack...

Seriously: What is the pulse wave?

It's the wave of deformation of the arterial wall following the shock of blood in the ascending aorta during a cardiac ventricular ejection shock.

While in a pool of water the wave propagates horizontally on the water surface, a pulse wave spreads over the surface of the blood in the arteries, then in a circular form in a centrifugal direction.

It's a wave that propagates faster than the speed of blood flow, on which is not dependent. (It travels more than ten times faster.)

The flow of blood through the arteries is parallel to the axis of the artery.

The pulse wave causes a measurable deformation of the arterial wall (it is perpendicular to the axis of the artery). It then propagates along the artery.