1127 Hepatic Blood Flow and Oxygen Delivery in Metabolic Syndrome

Abstract

INTRODUCTION: Metabolic syndrome MS is defined as the co-occurrence of metabolic risk factors for both DMII and cardiovascular disease. There is no consensus on the diagnostic criteria of the MS due to unclear pathogenesis uniting its components. We propose that compromised hepatic arterial blood supply and oxygen delivery as a response to a nutrient load in patients with MS will lead to hepatorenal activation of sympathetic overdrive, which can be the single common factor in MS pathogenesis METHODS: This prospective case-control study included patients 18-65 y/o diagnosed with MS and control healthy individuals with BMI 30-50 kg/m2. Subjects underwent an initial pre-prandial US, followed by drinking 8 oz of TwoCal high calorie drink immediately and in 15 mins. A second post-prandial US was performed 15mins after completing the second drink. US using the standard procedure for mesenteric artery examination for intestinal ischemia was performed to evaluate the diameter, velocity and flow of the superior mesenteric artery, hepatic artery, and portal vein. Both US images were interpreted by experienced diagnostic US radiologist. The results were analyzed using t-test RESULTS: Ten MS patients (age 55 ± 8) and ten control subjects (age 38 ± 11) with BMI 30-50 kg/m2 (37.6 ± 6.1) were compared. The relative change in blood flow in response to the nutrient load was reflected by the ratio of post- to pre-prandial readings. Total hepatic blood flow was calculated as the sum of HA and PV blood flow. The mean difference between post to pre-prandial ratio of total hepatic blood flow and total blood flow in all three vessels in MS group vs control group were 1.66 ± 0.57 vs 1.37 ± 0.40 (P = 0.162), 1.80 ± 0.42 vs 1.42 ± 0.27 (P = 0.025); respectively. The increase in postprandial total hepatic blood was 17.65% less in MS group. CONCLUSION: Why some obese patients develop MS while others don't raises the question of what is different between these cohorts. Excessive eating can produce obesity by causing chronic relative hypoxia in the liver. This produces sympathetic overdrive which causes insulin resistance, hypertension and dyslipidemia. Bariatric surgeries limit contact of nutrient with the GI mucosa resulting in increased splanchnic O2 delivery to the liver and preventing the hepatorenal reflex. The relative increase in total hepatic blood flow in response to a nutrient load was less in patients with MS compared to healthy obese controls. The difference was not statistically significant. Further studies with larger sample size needed.