99 Rational and Design of the MICORDIS study Figure 3. Contrast-enhanced transthoracic apical 4-chamber view end-systolic. After microbubble destruction with a high MI-pulse, replenishment of contrast is visible in the myocardium. (A–C) Subsequent replenishment of myocardial contrast, (D) ROI in the myocardial septum, (E) Example of myocardial replenishment in a time-video intensity curve. Fluctuations in the myocardial blood volume during replenishment, as demonstrated in this figure, is caused by the cardiac cycle of systole and diastole. Abbrevations: MI: Mechanical Index; ROI: Region of Interest; M: Myocardial; LV: Left Ventricle MCE is performed using the Philips iE33 (Philips Healthcare, Eindhoven, The Netherlands) ultrasound machine and is performed at baseline, after 2 h of hyperinsulinemia and during intravenous infusion of dobutamine. Following the first MCE-measurement at baseline, hyperinsulinemia is induced using the hyperinsulinemic-euglycemic (HE) clamp technique, developed by DeFronzo et al.44 The goal of HE-clamping is to raise insulin plasma concentrations to postprandial levels while maintaining normoglycemia. During HE-clamp insulin and glucose are simultaneously infused to minimize the effect of hyper- and hypoglycemia. At the start of the HE-clamp, the blood glucose level is measured. The clamp starts with two boluses of insulin, to lower stress-induced hyperglycemia. The first dose is 5 min of 4 times the normal insulin dose and the second bolus is 5 min of 2 times the normal insulin dose. The normal insulin dose is calculated with the formula: body surface area * 0,04 * 60.45 After 10 min insulin is infused in a continuous rate of 40 mU/m for 110 min.2 Infusion of 20% glucose solution is initiated simultaneously to maintain normoglycemia. During the administration of insulin, the blood glucose level is measured in 5 min intervals, and the glucose infusion rate is adjusted to maintain normoglycemia (i.e., blood glucose between 5 and 5.5 mmol/l). After 120 min of HE-clamp, steady-state glucose uptake has been reached and MCE is repeated. The insulin-induced ΔMBV is the difference between MBV at baseline and during hyperinsulinemia. The amount of glucose infused between the 90 and 120 min steady5
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