Obesity and vascular dysfunction: the fat-e of rich and poor

Endothelium-dependent vasoactivity of the human internal mammary artery

Coronary artery disease is recognized as a major health problem worldwide, particularly because of the associated morbidity and mortality. Coronary artery bypass grafting has been an established mainstay in the treatment of this disease for almost half a century and is arguably the most intensively studied surgical procedure ever undertaken. Because of its unique properties, the human internal mammary artery has long been considered the best graft to use in this type of surgery. Previous studies have shown several advantages of this graft compared with others, that is, lower incidence of atherosclerosis. However, few comparative studies on the reactivity of this artery have been published. Moreover, these studies usually focus on isolated cardiovascular risk factors rather than combined risk factors. In fact, patients who require coronary revascularization usually present multiple risk factors, which can interfere with several pathways of regulation of vascular function, namely endothelial function. Several diseases and cardiovascular risk factors have been shown to interfere with endothelial function, promoting the production of vasoconstrictors, inhibiting the production of vasodilators, or both, and thus eventually leading to endothelial dysfunction. Therefore, it is of great interest to study the endothelial function, particularly of the human internal mammary artery, in the presence of combined cardiovascular risk factors and concomitant diseases. Many techniques have been developed to assess the endothelial function, in particular, studies on isolated arteries, as well as spectroscopic, electrochemical, and immunological methods, among others.

Orlistat improves endothelial function in obese adolescents: a randomised trial

AIM

To investigate the effect of orlistat on endothelial function in obese adolescents.

METHODS

Single-blind 10-week controlled trial of 67 normolipidaemic obese adolescents randomised into three groups. Group 1 (diet alone), Group 2 (diet and orlistat), Group 3 (diet, orlistat and exercise). Endothelial function measured by flow-mediated dilatation (FMD) of the brachial artery, anthropometric parameters, blood pressure, fasting blood lipids, insulin and glucose levels were recorded at baseline and at 10 weeks.

RESULTS

Sixty four subjects completed the study. Groups were comparable at baseline. FMD increased significantly with orlistat (Groups 2 and 3) but not in Group 1. Orlistat treatment resulted in significantly reduced bodyweight, body mass index (BMI), waist circumference, total and low-density lipoprotein (LDL) cholesterol levels. High-density lipoprotein cholesterol levels were unchanged. Triglyceride and insulin levels were significantly reduced in all three groups. The reduction in cholesterols did not correlate with reductions in weight and BMI. A slight reduction of body fat, both with and without orlistat treatment, correlated with reduction in BMI after adjustment for baseline values. Blood pressure was unaltered by orlistat. Calorie intake was reduced with orlistat, and the decrease noted in % fat and increase in % carbohydrate was significant only in those taking orlistat. The addition of exercise (Group 3 compared with Group 2) altered no parameter.

CONCLUSIONS

Orlistat improves endothelial function and reduces bodyweight, BMI, fasting total and LDL-cholesterol in obese adolescents when combined with dietary control. Improvement in endothelial function if maintained could reflect long-term cardiovascular benefit.