Parallel imaging and dobutamine stress magnetic resonance imaging in patients with atypical chest pain or equivocal ECG not suitable for stress echocardiography.

PURPOSE: The aim of this study was to evaluate the clinical utility of cardiac magnetic resonance imaging (MRI) with dobutamine stress in patients with atypical chest pain or equivocal electrocardiography (ECG) stress test, not suitable for stress echocardiography, using steady-state free-precession and parallel imaging technique. MATERIALS AND METHODS: Thirty-three patients (22 men, 11 women; mean age 62.4 years) underwent MRI with a 1.5-Tesla imager (General Electric, HD). We used an eight-channel phase-array dedicated coil. The MRI protocol included short-axis cine steady-state sequences with four-chamber parallel imaging of the left ventricle outflow tract at rest and after stress induction. Images were acquired 3 min after the intravenous injection of 5,10, 20, 30 or 40 microg/kg/min dobutamine. MRIs were analysed both at rest and at incremental dobutamine doses. Results were considered positive for coronary artery disease (CAD) if any new or worsening wall motion abnormality developed during the stress test. Twenty-two patients underwent coronary angiography; in the remaining ten, survival free from cardiovascular events over at least 9 months was considered as absence of disease. RESULTS: One patient presented severe hypertension at rest and was excluded from our study. We analysed 960 segments and observed appearance or worsening of kinesis in 29 different segments in seven patients. Seven patients were considered positive for CAD on the basis of new or worsening wall motion abnormalities during dobutamine stress, yielding an overall sensitivity of 85% and a specificity of 100% in CAD detection. CONCLUSIONS: Dobutamine stress cardiac MRI is an accurate method for assessing myocardial ischaemia in patients with CAD, and it could be useful as a noninvasive tool for excluding the disease. The increase in signal intensity and acquisition speed obtained by using steady-state free precession with parallel imaging proved useful in increasing test specificity with respect to previous similar studies.

Clustering of endothelial markers of vascular damage in human salt-sensitive hypertension: influence of dietary sodium load and depletion.

The contributing role of vascular endothelium in the development of hypertension-related vascular damage is well accepted. Salt-sensitive hypertension is characterized by a cluster of renal, hormonal, and metabolic derangements that might favor the development of cardiovascular and renal damage. To evaluate endothelial involvement in salt-sensitive essential hypertension, plasma levels of several markers of endothelial damage such as endothelin-1 (ET-1), von Willebrand factor (vWf), and soluble (S-) adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and 24-hour urinary albumin excretion (UAE) were measured in 39 nondiabetic, nonobese, never-treated essential hypertensive patients after intermediate (120 mmol/d), high (220 mmol/d), and low (20 mmol/d) NaCl diets. Patients were classified as salt sensitive (n=18) or salt resistant (n=21) according to their blood pressure responses to changes in dietary NaCl intake. Salt-sensitive hypertensives showed higher plasma ET-1 (P<0.05), vWf (P<0.005), and S-E-selectin levels (P<0.04) and increased UAE (P<0.05) than salt-resistant hypertensives. By contrast, circulating S-ICAM-1 and S-VCAM-1 concentrations were not significantly higher in salt-sensitive (596. 56+/-177.05 ng/mL and 541.06+/-157.84 ng/mL, respectively) than salt-resistant patients (516.86+/-147.99 ng/mL and 449.48+/-158.91 ng/mL, respectively). During the intermediate NaCl diet, plasma ET-1 responses to oral glucose load were greater in salt-sensitive (P<0. 05) than in salt-resistant patients. A marked (P<0.05) hyperinsulinemic response to oral glucose load was evident in salt-sensitive but not salt-resistant patients after each diet. This study shows increased plasma levels of the endothelium-derived substances E-selectin, vWf, and ET-1 in salt-sensitive hypertensives. Our findings support the hypothesis that salt sensitivity is correlated with an increased risk for developing hypertension-related cardiovascular damage.

Electrolyte urinary excretion in hypertensive conditions.

Daily variations of electrolyte excretion have been studied in 8 hypertensive and in 4 normotensive women by collecting urine samples every 3 h for a 48-h span. After noticing the absence of a statistically significant circadian rhythm in the hypertensive group, the Authors suggest the hypothesis that a prolonged treatment with diuretic drugs may cause kidney troubles and suppress the circadian rhythm of urinary electrolyte excretion. The Authors conclude affirming that this hypothesis needs further investigation to allow a better chronotherapy of the hypertensive disease in the future.

Essential hypertension, chronobiological study of the circadian variations in urinary excretion of free catecholamines.

Arterial blood pressure and urinary free catecholamine excretion of 8 hypertensive and 4 normotensive women have been evaluated by 3-h interval samples for 2 consecutive days. After noticing the effects of sleep on the arterial blood pressure and on the daily variation of urinary free catecholamine excretion, the authors examined the possible different role of the adrenergic system in hypertensive subjects.

Circadian variation of aldosterone urinary excretion in idiopathic hypertension.

Daily variations of the urinary aldosterone excretion have been studied in 8 hypertensive and in 4 normotensive women. The examined subjects did not receive any drug for at least two weeks before the study and were under the same standardized life-conditions. The urine samples were collected every 3 h for two consecutive days. Population mean cosinor analysis by Halberg did not yield a statistically significant rhythm of aldosterone urinary excretion in the hypertensive group. Further investigation of the temporal structure of the renin-angiotensin-aldosterone system is therefore necessary.