Local endothelial dysfunction does not affect global endothelial function

Background: The purpose of this study was to evaluate two alternative non-invasive techniques for assessment of endothelial function in adults with special focus on their ability to monitor acute changes. Patients and methods: Twenty-five clinically healthy men (mean age 24 +/- 2 years) underwent endothelial function measurements twice in fasting state and twice after experimental induction of transient endothelial dysfunction by oral application of 0.1g/kg L-methionine and by ingestion of 500 ml whipped cream (30% fat), respectively. Microvascular vasodilator responses to Flickering-light by retinal vessel analysis and vascular responses to inhaled salbutamol by pulse wave analysis were assessed at each occasion. Ultrasound based flow-mediated dilation (FMD) was used as reference method. Results: Transient endothelial dysfunction in response to acute hyperlipidaemia and hyperhomocysteinaemia was verified by blunted brachial responses to hyperaemia. Retinal vessel analysis demonstrated significantly impaired flicker-responses of retinal vessels to both challenges depending on the vessel type. Pulse wave analysis did not show any significant changes in salbutamol responses. Reproducibility of retinal vessel analysis was comparable to FMD and slightly better than pulse wave analysis. Conclusions: Acute changes in endothelial function can be monitored by retinal vessel analysis with comparable reproducibility as FMD. Salbutamol based pulse wave analysis is currently unsuited to detect endothelial dysfunction in serial measurements.