Chronic heart failure (CHF) is associated with impaired endothelial dysfunction, including impairment of endothelium- mediated flow-dependent dilation (FDD). There is evidence that nitric oxide (NO) may be inactivated by radicals in CHF, resulting in impairment of the endothelium. Vitamin C is an antioxidant that may prevent the inactivation of NO by free radicals. This study explored the effect of intra-arterial and oral vitamin C on endothelial function in patients with CHF.
Fifteen patients with CHF and 8 healthy volunteers were studied. High-resolution ultrasound and Doppler probe were used to measure vascular changes. The vascular effects of vitamin C and placebo were determined at rest and during reactive hyperemia before and after intra-arterial infusion of N-monomethyl-L-arginine (L-NMMA) to inhibit endothelial synthesis of NO. Subjects received intra- arterial administration of either vitamin C (25 mg/min over 10 minutes) or placebo; 10 of the CHF patients later received 4 weeks of oral therapy with vitamin C (2 g/day) or placebo.
FDD was impaired in CHF patients compared to healthy controls. Vitamin C restored FDD in CHF patients (FDD was significantly increased and normalized) after acute intra-arterial administration and after 4 weeks of oral therapy, especially the portion of FDD mediated by nitric oxide (i.e., inhibited by L- NMMA). Neither forearm blood flow nor radial artery diameter was affected by vitamin C. FDD was not affected by vitamin C in the healthy individuals.
source: cardio consult reviews heart failure animations
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