Table 1.

Advantages and disadvantages of the most commonly used techniques to assess endothelial function

Technique	Vascular bed	Advantages	Disadvantages	Stimulus (examples)
Coronary epicardial vasoreactivity (QCA)	Epicardial macrovascular Conduit arteries	Assessment directly in the coronary vascular bed Gold standard	Invasive Expensive Time intensive Limited to those undergoing coronary angiography Challenging for serial measurements	Ach Exercise Pacing CPT
Coronary microvascular function – Doppler wires	Coronary microvascular Resistance arteries	Assessment directly in the coronary microvasculature	Invasive Expensive Time intensive Limited to those undergoing coronary angiography Challenging for serial measurements	Ach Adenosine Papaverine
Flow- Mediated- Dilation (FMD)	Brachial Artery Conduit artery	Easy access Correlation with invasive epicardial vascular function Many outcome studies Inexpensive Possibility to assess other important parameters (flow, baseline arterial diameters, FMC)	Challenging to perform well Disparate protocols for performance and standardizations Need for standardization	Reactive Hyperemia
Venous occlusion plethysmography	Forearm vasculature Microvasculature	Easy access Vasoactive substances infused to generate a dose-response relationship Contralateral arm as a control	Invasive (cannulation of the brachial artery) Time consuming	Ach and other vasoactive substances
EndoPAT	Finger Microvasculature	Easy to access and perform Automated Low inter- and intraobserver variability Correlation with invasive microvascular vascular function	Expense of disposable finger probes PAT signal influenced by variable non endothelial factors	Reactive hyperemia