PP.41.12

Abstract

Objective: Vascular remodeling in the retinal circulation represents an easily accessible, non-invasive, in-vivo possibility to assess early microvascular changes, especially as a model of brain microperfusion. In addition to the assessment of functional (e.g. retinal capillary flow, RCF) and retinal arterial structural parameters (e.g. wall-to-lumen-ratio, WLR) we now introduce a new parameter reflecting the resistance in small retinal arterioles. Design and method: In 66 normotensive (NT) and 107 hypertensive (HT) patients we assessed RCF, WLR, arteriolar diameter, lumen diameter and cross section area in the retinal circulation by using scanning laser doppler flowmetry SLDF at 670 nm (Heidelberg Retina Flowmeter, Heidelberg Engineering, Germany). Patients have been included in various randomized controlled trials, but with all the same study protocol at baseline. Mean arterial pressure was measured immediately before the SLDF measurement. We calculated the vascular resistance of the retinal arterioles (VRRA = MAP/RCF). In a separate study the test-retest reliability was determined in 6 volunteers from our clinical staff by assessing VRRA three times within six weeks. Results: The analysis of the volunteers revealed a coefficient of variation for VRRA of 7.75 ± 2.11% and Cronbach[Combining Acute Accent]s alpha was 0.90. The HT group did not show a more pronounced vascular remodeling of retinal arterioles (WLR, CSA, see table 1) compared to the NT group. In contrast RCF was greater in the HT group than in the NT group (p = 0.023). Our new suggested parameter VRRA was significantly greater in the HT group than in the NT group (p < 0.001). In both groups there is a significant correlation of VRRA with WLR (NT: r = 0.34, p = 0.006; HT: r = 0.25, p = 0.01), indicating that the VRRA reflects vascular remodeling in the retinal circulation.Conclusions: The analysis of the study data showed an increased vascular resistance in retinal arterioles in hypertensive patients compared to non-hypertensive patients before the occurrence of a change in structural retinal vascular remodeling parameters. The appearance of a significant correlation between VRRA and WLR indicates VRRA to be a new, reliable, non-invasive and early-sensitive marker of hypertensive disease.