Comparative study of microvascular function: Forearm blood flow versus dynamic retinal vessel analysis.

Objective: Recently, dynamic retinal vessel analysis (DVA) has gained interest for investigation of microvascular function but comparative measurements with standard methods like the forearm blood flow technique (FBF) are uncommon till now.
Methods: We recruited 23 high-risk cardiovascular patients (Risk) and 17 healthy persons (Ctrl). During the FBF experiment, postocclusive reactive hyperaemia (RH) as well as endothelium-dependent and independent vasodilation was measured by infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) into the brachial artery. The dynamic vessel analyzer was applied for measurement of the retinal arterial and venous response to flickering light during DVA and for determination of the central retinal arterial (CRAE) and venous equivalent (CRVE).
Results: Forearm blood flow technique was significantly attenuated in the patient group during postocclusive RH (p < .005). The increase of FBF in response to SNP did not differ significantly between the two groups (p = .09). In contrast, the FBF response to ACh was significantly blunted in the patient group (p < .05), indicating endothelial dysfunction. DVA did not detect any difference of retinal arterial (p = .68) or retinal venous (p = .93) vasodilation between both groups. The CRAE (p = .55) and CRVE (p = .83) did not differ significantly in either group.
Conclusions: Forearm blood flow and DVA cannot be regarded as equivalent methods for testing of microvascular function. Possible explanations include differences in the vascular beds and vessel diameters examined as well as differences in the trigger mechanisms applied. Further studies are needed to define the role of DVA in this context.
(© 2020 The Authors. Clinical Physiology and Functional Imaging published by John Wiley & Sons Ltd on behalf of Scandinavian Society of Clinical Physiology and Nuclear Medicine.)