ENDOTHELIAL DYSFUNCTION OCCURS IN CHILDREN WITH 2 GENETIC HYPERLIPIDEMIAS - IMPROVEMENT WITH ANTIOXIDANT VITAMIN THERAPY

Objective: To measure endothelium-dependent vascular relaxation in chi ldren with two genetic hyperlipidemias and to assess the effect of ant ioxidant vitamins on endothelial dysfunction. Study design: Vascular r eactivity in the brachial artery was measured in 45 individuals betwee n 6 and 21 years of age (18 with familial hypercholesterolemia [FH], 1 5 with familial combined hyperlipoproteinemia [FCH], 12 control subjec ts) with the use of high-resolution two-dimensional ultrasonography. F ollow up studies were done for 11 children after 6 weeks of treatment with tocopherol (400 IU twice a day) and ascorbic acid (500 mg twice a day). Results: The mean percent change in diameter during reactive hy peremia was 2.1 +/- 2.2 (SD) and 2.7 +/- 4.4, in FH and FCH, respectiv ely, compared with 12.4 +/- 4.9 among control subjects (p < 0.001 in e ach case). The mean percent dilation was significantly increased (2.8 +/- 1.6 to 9.1 +/- 2.3) (p < 0.001) after antioxidant therapy. Conclus ions: Impaired endothelium-dependent vasoregulation occurs in children with FCH as well as in those with FH. The improvement in vascular rea ctivity observed during supplementation with antioxidant vitamins sugg ests that reactive oxygen species derived from oxidized lipoproteins m ay be responsible for the impairment of vasoregulation in subjects wit h hyperlipidemia.