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R. Heitmar, D. Gherghel, R. P. Cubbidge, G. Y. Lip; Retinal and Peripheral Micro-vascular Reactivity in Patients Suffering From Coronary Artery Disease. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3273.
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To examine retinal and peripheral vascular reactivity in patients suffering from coronary artery disease (CAD) compared to age-matched healthy controls.
28 patients suffering from CAD and 30 age-matched healthy controls underwent nail-fold capillaroscopy (CAM1 Laser Doppler Capillary Anemometer, KKTechnology, Devon, UK) and dynamic retinal vessel assessment (DVA, Imedos GmbH, Jena, Germany). Capillary flow in nail-fold capillaries was assessed at baseline and the time needed to recover after cold provocation in both study groups. Retinal vascular diameters of arterioles and venules was measured continuously for 350 seconds according to following protocol: after an initial baseline measurement 3 cycles of each 20sec flicker light provocation followed by 80sec recovery was recorded, from those recordings we determined maximum dilation (MD), maximum constriction (MC), dilation amplitude (DA) and the time needed to reach maximum dilation (RT) in both, retinal arterioles and veins. Systemic BP has been continuously measured throughout the study day with an ambulatory BP unit (Cardio Tens-01, Meditech Ltd., Hungary) furthermore, IOP values were obtained by contact tonometry using the TonopenXL (TonopenXL, Medtronic Solan, PMS Instuments, Maidenhead, UK).
Although at the start of the experiment the measured circulatory parameters were comparable in both study groups, in patients suffering from CAD the blood flow at the level of the nail-fold capillaries needed significantly longer to recover to pre-provocation values after cold stimulation than in healthy controls (p=0.009). No significance in retinal vessel dynamics was found for MD, MC, DA and venous RT (all p>0.05) as assessed using RVA. However, arterial RT significantly increased for each stimulation cycle within the patient group, but not the control group (ANOVA, p=0.017).
CAD patients exhibit an impaired endothelial vascular response at the level of retinal arterioles, manifesting through a gradual increase in reaction time when stimulated with flickering light. Furthermore, a longer recovery time after cold provocation could suggest an increased vascular stiffness in micro-vascular beds at all levels in patients suffering from CAD.
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