Dynamic vessel analysis for assessing endothel dysfunction of microcirculatory vessels – method, model and results

Purpose To access the endothel function (flow induced autoregulation) provide a unique potential for vascular risk stratification,early recognition, diagnosis and treatment of big vascular heart and brain diseases by using the eye as a diagnostic window.It is assumed that Dynamic Vessel Analysis by DVA (Dynamic Vessel Analyzer Imedos GmgH Jena,Germany) is a practical and easy test for endothel dysfunction. Methods DVA can access vessel functions by use of flickering light.Online measurements of the diameter enable a highly reproducible observation of local and temporal changes of big retinal vessels with high accuracy.For functional analysis the retina is stimulated by a 12.5 Hz monochromatic flicker light.The stimulation period amounts 20s.The vessel response before, during an after stimuloation is recorded.Vessel dialation is estimated.To understand and for clinical interpretation of the flickering vessel response model of vessel response to flickering light was developed. Results In normal subjects flickering light induces an increase in vessel diameter.Reduced diameter dilatation is caused by exhausted regulative reserve (hypotonics) or by vascular dysfunction.The interpretation of the vascular dysfunction based on the following model:Flickering light is activating the neurovascular coupling, leading to a dilation of the capillaries and small arterioles.This causes an increase in flow leading to increased velocity in the bigger vessels indirectly.The flow induced autoregulation dilates the diameter of the big vessels by increasing nitric oxid NO via eNOS.Different experimental results support this model thesis. Conclusion The vessel dilatation can be explained by eNOS.Endothel dysfunction reduces the flicker dilatation. Commercial interest