Marguerite Roth

Adrenal Cortisol Hyper-Responsiveness as a Possible Cause of Obesity, Insulin Resistance and Cardiovascular Risk

Introduction: Increased cortisol concentrations due to endogenous over-secretion or exogenous administration result in obesity, insulin resistance, and increased risk of cardiovascular disease (CVD). We wanted to assess whether non pathological adrenal hyper responsiveness to ACTH could reproduce these changes and thus explain how stress, via the pituitary-adrenal axis, can also cause such abnormalities. Methods: ACTH stimulation test was performed on 1072 non diabetic healthy participants in the St. Francis Heart Study and multiple blood tests, anthropometric measurements and coronary calcium scores were also obtained. Results: Post stimulation cortisol concentrations were correlated with obesity, insulin resistance, lipid abnormalities, Framingham scores (all p ≤ 0.01), but not with blood pressure and not with coronary calcium scores. In multivariate models, increased cortisol secretion was significantly predictive of abdominal fat even after controlling for insulin resistance, and of insulin resistance even after controlling for abdominal fat. Conclusions: Adrenal hyper responsiveness may explain some of the observation of the relationship between stress and the metabolic abnormalities which can lead to CVD. Increased cortisol secretion predicts insulin resistance and obesity , independently of each other.

Left ventricular concentric remodeling in normal aging is associated with decline of diastolic function assessed by multi-modality imaging

In this carefully screened normal cohort, age dependent concentric remodeling was associated with significant decline in diastolic global function and mechanics, increased systolic torsion with preserved LVEF and a mild trend toward reduced systolic strain. Age related changes in diastolic function were more pronounced in women than in men.

The aging effect: The relationship of twist to structural and mechanical remodeling of the left ventricle in a normal population using HARP CMRI

Methods Forty-one normal volunteers were prospectively recruited. Subjects were nonobese, nondiabetic, normotensive and free of cardiovascular history or significant valvular or myocardial disease by screening echocardiography. After volumetric short axis retrospectively gated SSFP cine imaging (1.5 T Siemens Avanto), breath-hold retrospectively gated short axis tagged gradient echo cines were acquired in LV base, midventricular, and apical slices with a nominal FOV 21 × 28 cm, matrix 108 × 144, 6 mm slice thickness, grid tag distance of 8 mm, TE 3.8 ms, TR 58 ms, temporal resolution 35 ms. Tagged images were analyzed using HARP software (Diagnosoft). Results Of 41 individuals, 23 were females. The group was divided by age into tertiles. Twist increased with age>60 years while LV end systolic volume (LVESV) decreased, with associated increases in ejection fraction (LVEF), systolic blood pressure (SBP) and pulse pressure (PP). End diastolic volume (LVEDV), LV mass, systolic circumferential strain and strain rate did not change with age so that LV Mass/ESV ratio increased (Table 1).

Three-compartment modeling of chronic myocardial infarction gadolinium kinetics

Introduction The mechanism behind late gadolinium-enhanced (LGE) chronic myocardial infarct (MI) imaging is widely thought to be an increased gadolinium (Gd) concentration due to fibrotic tissue. Several groups have employed T1 measurements to measure the partition coefficient (ratio of tissue-to-blood Gd-concentrations) using a twocompartment model. A three-compartment model yields not only information about flow of Gd from the capillaries to the intracellular space, but in the case of chronic MI to fibrotic tissue and in the case of acute MI in the myocytes themselves. With model inputs of the LV bloodpool and tissue Gd-concentrations, the model yields transfer constants (K) between the compartments, compartment fractional volumes (v) and Gd-concentrations curves for tissue blood plasma, the extravascular extracellular space (EES) and fibrotic tissue. A detailed model may not only be useful to detect and characterize MI, but non-ischemic cardiomyopathies with global or diffuse fibrosis.

Association between left ventricular myocardial resting perfusion and intramyocardial fat deposition in patients with chronic myocardial infarction

Introduction Ischemic evaluation of the left ventricle (LV) by MR imaging can be performed using a combination of rest and stress images during a bolus contrast injection. Additionally, late-gadolinium-enhanced images are used determine the presence and extent of infarction. Myocardial tissue composition and vascular status may be determinants of myocardial blood flow in the resting and stress states. The effects of fibrosis as well as fat deposition on MR first-pass perfusion images have not been well studied. LV fat deposition is easily detected with MR imaging and is associated with chronic LV myocardial infarction, with a prevalence of approximately 60%. Assessment of perfusion in myocardial segments with fibrosis is clinically relevant for the determination of peri-infarct ischemia.

138 Relationship between coronary calcification and endothelium dependent coronary vaso-reactivity in asymptomatic diabetic patients without overt coronary artery disease

Methods We studied 23 (mean age 63 ± 10, 19 M, 4 F) patients with type II DM, without history, symptom or ECG evidence of CAD. The subjects underwent 1-day rest-stress adenosine nuclear stress test, assessment of coronary calcification by EBCT and absolute measurement of myocardial blood flow at rest (MBF-R), and following cold-water hand immersion for 1 minute (MBF-C). All imaging studies were performed within 24 hours. Flow measurements by CMRI was performed using saturation recovery TurboFLASH imaging sequence: TR/TE/TI/FA = 2.9 ms/1.3 ms/ 90 ms/6°, data matrix 128 × 70, and usual voxel spatial resolution 3.5 × 1.9 × 8 mm3. Contrast dose was 0.05 mmol/kg (Omniscan, Amersham). All scans were processed in a blinded fashion. Using Medis software (Leiden University, the Netherlands), basal, mid-cavity and apical slices were divided into 6 equal transmural sectors. After correction for coil sensitivity variations, model independent deconvolution of myocardial signal intensity curves in the sectors, with blood pool signal intensity curves was performed. MBF-R and MBF-C in mls/g/min were determined. Endothelium dependent perfusion reserve (MPR) in these sectors were calculated as the ratios of MBF-C to MBF-R in each sector. The sectors wre subsequently grouped based on standard coronary vascular distribution.

1010 Plaque burden as a determinant of coronary endothelial function

Introduction Normal coronary endothelial function(CEF) results in both epicardial coronary artery lumen dilation and increased coronary flow due to downsteam microvascular vasodilation during cold pressor testing (CPT) or intracoronary injection of acetylcholine,. We have previously developed noninvasive MRI methods to assess both components of CEF using CPT and have shown that presence of risk factors blunts or abolishes increased flow during CPT.