Abstract
Diabetes mellitus affects distal small vessels earlier and to a greater extent than proximal vessels. Vascular disease starts from activation of the endothelial cells, which if prolonged may lead to reduced distensibility of the vessel when maximally stimulated. Hence a device which measures distensibility of a distal vessel should be a good biomarker for subclinical disease. We have developed a device capable of measuring reactive hyperaemia induced changes in the radial artery flow, volumetric changes and accompanying effects on the vessel wall. The measurement is based on the magnetic flux disturbance upon haemodynamic modulation as blood flows through a uniformly applied magnetic field, and generates what we have termed the radial artery maximum distensibility index (RA-MDI). In a proof-of-concept study we found significant correlations between RA-MDI and cardiovascular risk factors, scoring systems and carotid artery intima-media thickness. Further large scale prospective studies need to be conducted to ascertain the correlations with cardiovascular events.
Highlights
There are several methods that measure endothelial function in a research setting such as cardiac catheterisation, venous occlusion plethysmography, ultrasound brachial artery flow-mediated dilation (FMD) and pulse amplitude tonometry (PAT)[9,10]
Patients with T2DM had a higher body mass index (BMI), waist circumference, and systolic and diastolic blood pressure (BP) compared to healthy volunteers
The patients with T2DM had a much higher cardiovascular risk estimated by all the Framingham risk scores
Summary
There are several methods that measure endothelial function in a research setting such as cardiac catheterisation, venous occlusion plethysmography, ultrasound brachial artery flow-mediated dilation (FMD) and pulse amplitude tonometry (PAT)[9,10]. The use of brachial artery FMD for measurement of endothelial dysfunction was described and a standardised protocol was developed[2] This method measures the flow-mediated changes in the diameter of the brachial artery using ultrasound. The brachial artery diameter is affected by reflex stimuli resulting in direct sympathetic vasoconstriction[14] It is a muscular artery and flow related dynamics will be dependent to some extent on the muscular build of the individual. This method has high inter-user and intra-operator variability as a result of the angle and location of the ultrasonic scanner. The capillaries are much smaller and may provide an even earlier indicator, they are prone to changes in the environment like exposure to cold
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