Investigating vascular function

To assess the state of vascular function in humans, several methods have been available on the “vascular function exploration” technical platform since 2010. The development of these non-invasive methods was carried out in collaboration with the Clermont-Ferrand Clinical Investigation Center (CIC) (Prof. C. Dubray) and the Cardiology Department of the Clermont-Ferrand CHRU (Prof. P. Mottref, Dr N. Barber-Chamoux). Marie-Anne Verny (NutriVasc Team), has been trained in these techniques and carries out all the vascular measurements required for clinical studies.
The platform is located at the CIC.

Equipement et measurements :

To assess vascular function using non-invasive methods, the technical platform is equipped with the following equipment :

Echographe Vivid S5 (GE)

•  Vasodilatation Dépendante du Débit (VDD) ou Flow Mediated Dilatation (FMD) et Débit sanguin.

In the macro-circulation, endothelial function is assessed after induction of post-occlusive reactive hyperemia by measuring VDD (or FMD) and blood flow in the brachial artery using Doppler ultrasound (VIVID S5 GE).

FMD (%) = ((maximum artery diameter – basal artery diameter) / basal artery diameter) *100

• Intima/media thickness

Intima-media thickness in the carotid artery is correlated with the occurrence of cardiovascular events. This parameter is measured by ultrasound (VIVID S5).

Endo-PAT 2000 (Itamar Medical Ltd)

In the peripheral circulation, endothelial function is assessed by tonometry using the Endo-PAT 2000 system (Itamar) before and after induction of post occlusive reactive hyperemia. Endothelium-induced changes in vascular tone are measured at fingertip level using a pair of disposable plethysmographic sensors.
The result is the Reactive Hyperemia Index (RHI, %), which corresponds to the ratio between the amplitudes of the PAT® signal during hyperemia and the basal amplitudes on the occluded side, normalized by the values of the control arm.
Normal: RHI > 1.67
Abnormal: RHI ≤ 1.67
This device also provides the value of the Augmentation Index (AIx), a measure of microvascular stiffness calculated from the pulse waveform recorded in basal. This measure is a recognized marker of cardiovascular risk, not necessarily correlated with endothelial function.

The AI value is inversely proportional to vessel stiffness.

Periflux Perimedes (SA)

At microcirculation level, the PF 5010 Doppler laser (Perimed) measures changes in total local microcirculatory blood perfusion induced by post-occlusive hyperemia, local heating or iontophoresis

SphygmoCor (CPV ATCOR Medical)

Arterial stiffness is considered the main factor in arterial aging and a major risk factor for cardiovascular disease.
This parameter is assessed by measuring the Pulse Wave Velocity (PWV) between the carotid and femoral arteries using tonometry with the Sphygmocor. The PWV value is proportional to arterial stiffness