Noninvasive determination of endothelial cell function in the microcirculation in Kawasaki syndrome.

The aim of the study was to noninvasively assess endothelial cell (EC) function in the microcirculation using laser Doppler fluximetry (LDF) in acute and convalescent Kawasaki syndrome (KS) patients and healthy controls. KS is an acute, self-limited vasculitis of childhood that affects the EC of medium-sized arteries. No studies have addressed EC function in the peripheral microcirculation. LDF preacetylcholine and postacetylcholine (ACh) iontophoresis estimates microcirculation EC nitric oxide production leading to smooth muscle relaxation and vasodilatation, which are blunted in EC dysfunction. We studied a total of 97 subjects: 36 acute and 27 convalescent KS patients and 34 normal children. Change in blood flow was measured by LDF for 10 min post-ACh iontophoresis. Acute KS patients had significantly lower average flux when compared to convalescent KS patients and controls in the first 5 min postiontophoresis. However, there was no difference in flux or area under the curve (AUC) between convalescent KS patients and healthy controls. Despite a reduced response of the microvascular EC to ACh in acute KS patients, convalescent patients with and without coronary aneurysms had microvascular EC function similar to normal controls. This suggests that the EC injury in KS is confined to the endothelium of medium-sized arteries and that microvascular EC function is normal after acute KS.