Atherosclerosis measured by whole body magnetic resonance angiography and carotid artery ultrasound is related to arterial compliance,but not to endothelium‐dependent vasodilation – the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

Background: Arterial compliance and endothelium‐dependent vasodilation are two characteristics of the vessel wall. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, we studied the relationships between arterial compliance and endothelium‐dependent vasodilation versus atherosclerosis as measured with two imaging modalities. Methods: In the population‐based PIVUS study (1016 subjects aged 70), arterial compliance was determined by ultrasound in the carotid artery and the stroke volume to pulse pressure ratio by echocardiography, while endothelium‐dependent vasodilation was assessed by the invasive forearm technique with acetylcholine and brachial artery ultrasound. Intima‐media thickness was evaluated by ultrasound in the carotid artery (n = 954). Stenosis in the carotid, aorta, renal, upper and lower leg arteries were determined by magnetic resonance angiography in a random subsample of 306 subjects. Results: After adjustments for gender, Framingham risk score, obesity, myocardial infarction and stroke, distensibility in the carotid artery and the stroke volume to pulse pressure ratio were both significantly related to a weighted index of stenosis in the five arterial territories evaluated by magnetic resonance angiography (p<0·02 for both). Distensibility in the carotid artery (P = 0·021), but not the stroke volume to pulse pressure ratio (P = 0·08), was also significantly related to intima‐media thickness. Conclusion: In the elderly population, atherosclerosis is mainly related to arterial compliance, but not to endothelium‐dependent vasodilation in peripheral conduit or resistance vessels.     

Arterial stiffness, but not endothelium-dependent vasodilation, is related to a low Ankle-Brachial index. The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS)

Background: Arterial compliance and endothelium‐dependent vasodilation are two characteristics of the vessel wall. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study we studied the relationships between arterial compliance and endothelium‐dependent vasodilation versus the Ankle‐Brachial index (ABI), a clinically used index of peripheral artery disease. Methods: In the population‐based PIVUS study (all aged 70), arterial compliance was determined by ultrasound as the distensibility of the carotid artery and the stroke volume to pulse pressure (SV/PP) ratio by echocardiography, while endothelium‐dependent vasodilation was assessed by the invasive forearm technique with acetylcholine (EDV) and brachial artery ultrasound (FMD) in 519 subjects in whom the Ankle‐Brachial index was investigated. Results: After adjustments for gender and Framingham risk score, distensibility in the carotid artery and the SV/PP ratio were significantly reduced in subjects with a reduced ABI (<0·9) in both legs (n = 15, P = 0·0006 and P = 0·0003, respectively). Endothelium‐dependent vasodilation was not significantly related to a reduced ABI. Conclusion: A reduced arterial compliance, but not endothelium‐dependent vasodilation, was related to a low ABI in both legs after adjustment for major risk factors, suggesting that atherosclerosis in the leg arteries is associated with arterial compliance also in other parts of the vasculature.     

Evaluation of aortic geometries created by magnetic resonance imaging data in healthy volunteers

Introduction: The development of atherosclerotic plaques has been associated with the patterns of wall shear stress (WSS). However, much is still uncertain with the methods used to calculate WSS. Correct vessel geometries are mandatory to get reliable estimations, and the purpose of this study was to evaluate an in vivo method for creating aortic 3D geometry in human based on data from magnetic resonance imaging (MRI) with ultrasound as reference. Methods: The aortas of ten healthy men, 23·4 ± 1·6 years of age, were examined with a 1·5 T MRI system using a 3D gadolinium‐enhanced gradient‐echo sequence. Three‐dimensional geometries were created using manual segmentation of images. Lumen diameters (LD) were measured in the abdominal aorta (AA) and the thoracic aorta (TA) with non‐invasive B‐mode ultrasound as a reference. Results: The anteroposterior diameter of the AA was 13·6 ± 1·1 mm for the MRI and 13·8 ± 1·3 mm for the ultrasound (NS). Intraobserver variability (CV) for MRI and ultrasound was <0·92% and <0·40%, respectively. Interobserver variability for MRI and ultrasound was 0·96% and 0·56%, respectively. The diameter of the TA was 19·2 ± 1·4 mm for the MRI, and the intraobserver variability (CV) was <0·78% and interobserver variability (CV) was 0·92%. Conclusion: Specific arterial geometries can be constructed with a high degree of accuracy using MRI. This indicates that the MRI geometries may be used to create realistic and correct geometries in the calculation of WSS in the aorta of human.     

Validation of non‐invasive haemodynamic methods in patients with liver disease: the Finometer and the Task Force Monitor

Patients with advanced cirrhosis often present a hyperdynamic circulation characterized by a decrease in systolic and diastolic blood pressure (SBP and DBP), and an increase in heart rate (HR) and cardiac output (CO). Accurate assessment of the altered circulation can be performed invasively; however, due to the disadvantages of this approach, non‐invasive methods are warranted. The purpose of this study was to compare continuous non‐invasive measurements of haemodynamic variables by the Finometer and the Task Force Monitor with simultaneous invasive measurements. In 25 patients with cirrhosis, SBP, DBP and HR were measured non‐invasively and by femoral artery catheterization. CO was measured non‐invasively and by indicator dilution technique. The non‐invasive pressure monitoring was considered acceptable with a bias (accuracy) and a SD (precision) not exceeding 5 and 8 mmHg, respectively, as recommended by the Association for the Advancement of Medical Instrumentation. The accuracy and precision of the Finometer and the Task Force Monitor were as follows: SBP: ?3·6 ± 17·9 and ?8·9 ± 17·5 mmHg, respectively; DBP: 4·2 ± 9·6 and 1·9 ± 8·6 mmHg, respectively; HR: 2·0 ± 6·9 and 2·2 ± 6·2 bpm, respectively; and CO: 0·1 ± 1·6 and ?1·0 ± 2·0 L min^?1, respectively. The study demonstrates that the overall performances of the Finometer and the Task Force Monitor in estimating absolute values of SBP, DBP, HR and CO in patients with cirrhosis are not equivalent to the gold standard, but may have an acceptable performance with repeated measurements.     

Diameter and compliance of the greater saphenous vein - effect of age and nitroglycerine

Objectives: The greater saphenous vein (GSV) is commonly used in autologous vein graft surgery. GSV diameter has proven to influence graft patency, and furthermore venous compliance might be of importance. The purpose of the study was to evaluate the effect of age on GSV diameter and compliance, and to evaluate the effect of nitroglycerine (NTG). Methods: The diameter and compliance of the GSV, with and without NTG, were examined with B‐mode ultrasound in 12 elderly (70·3 ± 1·2 year) and 15 young (25·1 ± 0·6 year) men. The GSV diameter at the thigh and calf level was measured at rest, after 6 min of venous stasis (60 mmHg) and after NTG administration. Pressure–area curves during a linear venous pressure decrease were produced. Venous compliance was calculated using the quadratic regression equation (area) = β₀ + β₁ (cuff pressure) + β₂ (cuff pressure)². Results: GVS diameter between the groups showed significant lower diameter in elderly compared to young men (P<0·05). Venous occlusion increased GSV diameter in elderly men (P<0·01) as well as young men (P<0·001). NTG increased GSV diameter in elderly men (P<0·01) with an equal trend in young men. During venous occlusion, after administration of NTG, GSV diameter increased further in both elderly (P<0·01) and young men (P<0·001). GSV compliance was decreased in elderly (β₁, 0·037 ± 0019, β_2,?0·000064 ± 00017) versus young men (β₁, 0·128 ± 0·013, β₂, ?0·00010 ± 000018) [P<0·001 (β₁), P<0·02 (β₂)]. Conclusions: Baseline GSV diameter as well as GSV compliance is decreased in elderly men compared to the young subjects. As reduced GSV diameter as well as reduced compliance is related to decreased graft patency, these findings might be of importance for the uses of GSV as graft material in cardiovascular bypass surgery. The clinical value has to be clarified in future studies.     

Arterial compliance and endothelium-dependent vasodilation are independently related to coronary risk in the elderly: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

Background: Measurements of both arterial compliance and endothelium‐dependent vasodilation have previously been related to coronary risk factors, but not in the same study. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, we studied the interplay between arterial compliance and endothelium‐dependent vasodilation on coronary risk. Methods: In the population‐based PIVUS study (1016 subjects aged 70 years), arterial compliance was determined by ultrasound in the carotid artery, by pulse wave analysis (augmentation index) and the stroke volume to pulse pressure ratio by echocardiography, while endothelium‐dependent vasodilation (EDV) was assessed by the invasive forearm technique with acetylcholine , brachial artery ultrasound [flow‐mediated dilatation (FMD)] and pulse wave analysis with terbutaline provocation [change in reflection index (RI)]. Results: Factor analysis disclosed three major factors. The first factor was reflecting the three arterial compliance methods, the second factor was reflecting EDV and the change in RI, while the third factor mainly was reflecting FMD. All these three factors were independently related to the Framingham risk score in multiple regression analysis (P<0·0001, P = 0·0002 and P = 0·0046, respectively). Conclusions: In conclusion, both arterial compliance and endothelium‐dependent vasodilation were independently related to the Framingham risk score, suggesting that it is worthwhile to evaluate the parallel use of these two vascular characteristics in a prospective fashion.     

Association of carotid arterial distensibility with Doppler indices of left ventricular filling in 50-year-old subjects

Doppler indices of left ventricular diastolic filling are associated with various cardiac and extracardiac factors. Afterload is one of the extracardiac factors influencing left ventricular diastolic filling. The distensibility of the great arteries is one of the components of afterload. In this study, the relation between Doppler indices of left ventricular filling and the distensibility of the common carotid arteries was investigated. We studied 237 subjects at 50 years of age with Doppler echocardiography and ultrasound examination of the common carotid arteries. The following Doppler indices of left ventricular filling were studied: peak early diastolic velocity E-wave, peak atrial diastolic velocity A-wave and early to atrial peak velocity ratio, E/A. Carotid arterial characteristics were: distensibility coefficient, carotid arterial diameter change in systole and fractional change in the carotid arterial diameter. The relation between Doppler indices of left ventricular filling and carotid arterial characteristics was assessed by univariate and multivariate regression analysis. There was a significant univariate, positive association between E/A ratio and carotid arterial distensibility (r = 0·27, P<0·001), carotid arterial systolic diameter change (r = 0·19, P<0·005) and fractional change of the carotid arterial diameter (r = 0·20, P<0·005). In multivariate analysis, E/A ratio was independently associated with carotid arterial distensibility (P<0·005), after adjusting for heart rate, body mass index and gender. Decreased carotid arterial distensibility was associated with a reduction in E/A ratio, suggesting that arterial distensibility may have an effect on left ventricular diastolic filling or that changes in the arterial elastic properties are associated with corresponding structural changes in the left ventricle.     

Factors influencing 133‐xenon washout in a nose‐sinus model

The 133‐xenon washout technique is a non‐invasive method for the evaluation of ventilation of the paranasal sinuses. The half‐time of 133‐xenon washout (T½) is considered to reflect sinus ostial function and sinus ventilation. However, it is not known how morphological and physiological factors affect the washout from the paranasal sinuses. The aim of the present study was to evaluate how sinus volume, ostial diameter and nasal ventilation influence 133‐xenon washout in a nose‐sinus model. This is important for the interpretation of measurements of 133‐xenon washout from paranasal sinuses in healthy subjects and in subjects with sinus disease. The 133‐xenon washout was measured with a scintillation camera. The statistical analysis of the results showed that the logarithm (to the base 10) of the half‐time of 133‐xenon washout is linearly related to the ostial diameter, the sinus volume and the nasal ventilation in the model. In a multiple linear regression model, the most important factor contributing to 133‐xenon washout was found to be the ostial diameter, which explained 76% of the variation in log T½. In the same statistical model the sinus volume explained 7·5% and the ventilation 5·3% of the variation in log T½. Calculations of the functional ostial diameter in healthy subjects were made, based on the results of the model study. The mean functional ostial diameter was found to be 3·5 mm (range 0·5–7·5 mm). The results obtained with the present model experiments may be of importance for the correct interpretation of the results of measurements of 133‐xenon washout in healthy subjects and patients.     

Impaired coronary artery distensibility is an endothelium‐dependent process and is associated with vulnerable plaque composition

Coronary endothelial‐dependent microvascular dysfunction, an early reversible stage of coronary artery disease (CAD), is associated with poor clinical outcome. The current study investigated whether coronary artery distensibility index (CDI) is associated with: (i) coronary endothelial‐dependent microvascular dysfunction and (ii) vulnerable plaque composition among subjects with non‐obstructive CAD. Seventy‐four subjects with non‐obstructive CAD (luminal stenosis <30%) were studied. In 20 subjects with and without coronary endothelial‐dependent microvascular dysfunction, coronary flow reserve (CFR) of target segment during intracoronary (IC) infusion of acetylcholine (Ach) and bolus injection of adenosine as well as CDI at rest of corresponding target segment were measured. In 54 subjects, plaque compositions and CDI at rest of 154 non‐obstructive coronary segments as well as proximal segment without disease were measured by intravascular ultrasound (IVUS). CDI was defined as: [(Early‐diastolic cross‐sectional‐area (CSA) – End‐diastolic CSA of target segment)/(end‐diastolic CSA of target segment × coronary‐pulse‐pressure) × 10³]. There is a direct association between endothelial dysfunction and impaired CDI of a coronary segment both in the given coronary segment and corresponding microvessels in which a strong agreement between CDI and CFR Ach (r² = 0·85, P = 0·0001) was observed. Multivariable regression‐analysis showed that CDI was an independent predictor of the vulnerable plaque characteristics. The risk of impaired CDI was 125% higher in segments with necrotic core and 60% higher in segments with fibrofatty components as compared to normal segments (P = 0·001). In conclusions, the current study reveals that impaired CDI is an endothelial‐dependent process of both given coronary segment and corresponding microvessels and is associated with vulnerable plaque composition.     

In Vivo Noninvasive Temperature Measurement by B‐Mode Ultrasound Imaging

Objective. This study investigated the use of ultrasound image analysis in quantifying temperature changes in tissue, both ex vivo and in vivo, undergoing local hyperthermia. Methods. Temperature estimation is based on the thermal dependence of the acoustic speed in a heated medium. Because standard beam‐forming algorithms on clinical ultrasound scanners assume a constant acoustic speed, temperature‐induced changes in acoustic speed produce apparent scatterer displacements in B‐mode images. A cross‐correlation algorithm computes axial speckle pattern displacement in B‐mode images of heated tissue, and a theoretically derived temperature‐displacement relationship is used to generate maps of temperature changes within the tissue. Validation experiments were performed on excised tissue and in murine subjects, wherein low‐intensity ultrasound was used to thermally treat tissue for several minutes. Diagnostic temperature estimation was performed using a linear array ultrasound transducer, while a fine‐wire thermocouple invasively measured the temperature change. Results. Pearson correlations ± SDs between the image‐derived and thermocouple‐measured temperature changes were R² = 0.923 ± 0.066 for 4 thermal treatments of excised bovine muscle tissue and R² = 0.917 ± 0.036 for 4 treatments of in vivo murine tumor tissue. The average differences between the two temperature measurements were 0.87°C ± 0.72°C for ex vivo studies and 0.97°C ± 0.55°C for in vivo studies. Maps of the temperature change distribution in tissue were generated for each experiment. Conclusions. This study demonstrates that velocimetric measurement on B‐mode images has potential to assess temperature changes noninvasively in clinical applications.     

Analysis of human myocardial dynamics using virtual markers based on magnetic resonance imaging

Background: Myocardial dynamics are three‐dimensional (3D) and time‐varying. Cineradiography of surgically implanted makers in animals or patients is accurate for assessing these events, but this invasive method potentially alters myocardial motion. The aim of the study was to quantify myocardial motion using magnetic resonance imaging (MRI) and hence to provide a non‐invasive approach to characterize 3D myocardial dynamics. Methods: Myocardial motion was quantified in ten normal volunteers by tracking the Lagrangian motion of individual points (i.e. virtual markers), based on time‐resolved 3D phase‐contrast MRI data and Fourier tracking. Nine points in the myocardium were tracked over the entire cardiac cycle, allowing a wire frame model to be generated and systolic and diastolic events identified. Results: Radius of curvature of the left ventricular (LV) wall was calculated from the virtual markers; the ratio between the anterior–posterior (AP) and septal–lateral (SL) walls in the LV shows an oval shape of the apical short axis plane at end systole (ES) and more circular at end diastole (ED). The AP/SL ratio for the basal plane shows an oval shape at ES and ED. We found that the rotation of the basal plane in ES was less compared to the apical plane [?2·0 ± 2·2 versus 4·1 ± 2·6 degrees (P<0·005)]. The apical plane rotated counter clock wise as viewed from the apex. Conclusion: This new non‐invasive tool, despite current limitations in temporal and spatial resolution, may provide a comprehensive set of virtual myocardial markers throughout the entire LV without the confounding effects introduced by surgical implantation.     

Labelling dendritic cells with SPIO has implications for their subsequent in vivo migration as assessed with cellular MRI

An optimized non‐invasive imaging modality capable of tracking and quantifying in vivo DC migration in patients would provide clinicians with valuable information regarding therapeutic DC‐based vaccine outcomes. Superparamagnetic iron oxide (SPIO) nanoparticles were used to label bone marrow‐derived DC. In vivo DC migration was tracked and quantified non‐invasively using cellular magnetic resonance imaging (MRI) in a mouse model. Labelling DC with SPIO reflects the kinetics of DC migration in vivo but appears to reduce overall DC migration, in part due to nanoparticle size. Magnetic separation of SPIO‐labelled (SPIO⁺) DC from unlabelled (SPIO^?) DC prior to injection improves SPIO⁺ DC migration to the lymph node. Corresponding MR image data better correlate with the presence of DC in vivo; an improved immunological response is also seen. Cellular MRI is a viable, non‐invasive imaging tool that can routinely track DC migration in vivo. Consideration should be given to optimizing MRI contrast agent‐labelling of clinical‐grade DC in order to accurately correlate DC fate to immunological outcomes in patients. Copyright © 2011 John Wiley & Sons, Ltd.     

Factors associated with compliance to thiazide diuretics among 8551 Chinese patients

What is known and Objective: Good compliance to anti‐hypertensive medications has been recognized as a crucial factor to achieve optimal blood pressure control, but there were few studies addressing this issue among ethnic Chinese patients. This study aims to evaluate the factors associated with compliance to thiazide diuretics in a Chinese hypertensive population. Methods: From a clinical database, all adult Chinese patients aged ≥18 years who were prescribed a thiazide diuretic from the public health care sector in one large Territory of Hong Kong during January 2004 to June 2007 and attended at least twice for anti‐hypertensive drug refill were included. Medication Possession Ratios were used to measure drug compliance for each patient, with a level ≥80% defined as compliant. We used binary logistic regression analysis to evaluate the factors associated with good compliance. Results and Discussion: From 8551 eligible patients, 84·5% were compliant (defined as MPR ≥ 80%). Fee payers (adjusted odds ratio [aOR] 1·28; 95% CI 1·12–1·46, P < 0·001) and follow‐up visitors (aOR 2·47, 95% CI 2·13–2·87, P < 0·001) were significantly associated with better anti‐hypertensive compliance. Patients who were newly prescribed thiazide diuretics and those with poorer socioeconomic status were more likely to be non‐compliant to anti‐hypertensive therapies. Patients’ age, gender and number of co‐morbidities were not significant associated factors. What is new and Conclusion: Among Chinese patients, those who were newly prescribed thiazide diuretics and those with poorer socioeconomic status were more likely to be non‐compliant to anti‐hypertensive therapies. Closer monitoring and more intensive compliance‐enhancing strategies had to be targeted towards these patients to enhance clinical outcomes.     

Relationship of asymmetric dimethylarginine with flow-mediated dilatation in subjects with newly detected severe hypercholesterolemia

Background: Little is know about the relationship between asymmetric dimethylarginine (ADMA) and percent flow‐mediated dilatation (%FMD) in subjects with severe hypercholesterolemia (HH). Aim: The aim the present study was the evaluation of the relationship of ADMA to %FMD, as well as to lipid parameters and other markers of endothelial dysfunction in newly detected subjects with severe HH. Methods: One hundred and twenty asymptomatic patients with severe, newly detected HH and 100 controls were evaluated. The plasma level of ADMA was tested by ELISA and total homocysteine (tHcy) – through fluid chromatographic analysis. The %FMD was evaluated by the diameter of brachial artery with 7·5 MHz transducer of HP SONOS 5500. Results: Significant difference was found between patients and controls, (P<0·05) regarding lipid total cholesterol, triglycerides, high‐density lipoprotein, low‐dencity lipoprotein, atherogenic indices) and non‐lipid markers (ADMA, sICAM‐1, sVCAM‐1), as well as the endothelium dependent %FMD in contrast to flow independent vasodilation. (P>0·05) No significant difference was found between the groups with respect to tHcy, P‐selectine and E‐selectine. (P>0·05) A strong negative correlation was found between %FMD and ADMA. (r_xy = ?0·895; P<0·001), Apolipoprotein‐B (r_xy = ?0·687; P<0·0001, tHcy (r_xy = ?0·560; P<0·001) and Apolipoprotein index –B/A1 (r_xy = ?0·518; P<0·001). The subsequent linear and multiple regression analysis selected ADMA as the most significant factor in relation to %FMD. Conclusion: It is concluded that ADMA is the basic modulator of %FMD among all tested atherogenic risk biomarkers in in newly detected subjects with severe HH.     

Assessment of Carotid Stiffness and Intima‐Media Thickness From Ultrasound Data

Objective. Increased arterial stiffness and carotid intima‐media thickness (IMT) are considered independent predictors of cardiovascular events. The aim of this study was to compare a system recently developed in our laboratory for automatic assessment of these parameters from ultrasound image sequences to a reference radio frequency (RF) echo‐tracking system. Methods. Common carotid artery scans of 21 patients with cardiovascular risk factors and 12 healthy volunteers were analyzed by both devices for the assessment of diameter (D), IMT, and distension (ΔD). In the healthy volunteers, analyses were repeated twice to evaluate intraobserver variability. Agreement was evaluated by Bland‐Altman analysis, whereas reproducibility was expressed as a coefficient of variation (CV). Results. Regarding the agreement between the two systems, bias values ± SD were 0.060 ± 0.110 mm for D, –0.006 ± 0.039 mm for IMT, and –0.016 ± 0.039 mm for ΔD. Intraobserver CVs were 2% ± 2% for D, 5% ± 5% for IMT, and 6% ± 6% for ΔD with the RF echo‐tracking system and 2% ± 1% for D, 6% ± 6% for IMT, and 8% ± 6% for ΔD with our automated system. Conclusions. Although B‐mode‐based devices are less precise than RF‐based ones, our automated system has good agreement with the reference method and comparable reproducibility, at least when high‐quality images are analyzed. Hence, this study suggests that the presented system based on image processing from standard ultrasound scans is a suitable device for measuring IMT and local arterial stiffness parameters in clinical studies.     

Correlations between Arteriograph-derived pulse wave velocity and aortic elastic properties by echocardiography

Introduction: There is an increased scientific interest on the evaluation of parameters characterizing aortic elasticity. The current study was designed to compare two characteristics of aortic distensibility: Arteriograph‐derived pulse wave velocity (PWV) and augmentation index standardized to 80 per minutes heart rate (AIx80) and aortic elastic properties by echocardiography. Methods: The study comprised 21 adult healthy volunteers. In all cases, systolic and diastolic ascending aortic diameters were recorded during transthoracic echocardiography in M‐mode at a level 3 cm above the aortic valve from a parasternal long‐axis view. Using forearm blood pressure values, the following aortic elastic properties were calculated: aortic strain, distensibility and stiffness index. All patients were examined by Arteriograph at the same time, as well. Results: The Arteriograph‐derived AIx80 and PWV correlated with aortic strain (R = ?0·495, P = 0·023 and R = ?0·527, P = 0·014, respectively) and aortic stiffness index (R = 0·454, P = 0·039 and R = 0·608, P = 0·003, respectively). Aortic distensibility did not correlated with AIx80 (R = ?0·344, P = 0·127), only with PWV (R = ?0·593, P = 0·005, respectively). Discussion: Low to moderate correlations could be demonstrated between Arteriograph‐derived PWV and aortic elastic properties by echocardiography.     

A methodological study of arterial wall function using ultrasound technique

We aimed to establish reference values for three important properties of the arterial wall using a conventional ultrasound scanner. We measured: (1) intima–media thickness (IMT) of the carotid arteries with the internal trace function of the ultrasound system; (2) wall stiffness by pulsatile diameter changes in the right common carotid artery assessed by M-mode; and (3) endothelial function expressed as flow-mediated dilatation (FMD) of the brachial artery. IMT and wall stiffness measurements and reproducibility were compared with those obtained by external analysing systems. All variables were obtained in healthy subjects (n = 20), 29–53 years old. IMT increased with age (P<0·01). There was no difference in IMT between men and women. The inter-operator variability for measuring IMT was 6–9%. The same order of reproducibility was obtained with an external PC-based analysing system. Regarding wall stiffness, no correlation was found with age, nor any difference between men and women. A low intra-operator variability (CV < 10%) was found for measurements of wall stiffness with both M-mode and an external wall tracking system. FMD of the brachial artery diminished with age (P<0·01). There was a relation between FMD and brachial artery size (P<0·01) and, therefore, as men have larger arterial diameters (P<0·01), smaller FMD in men. We conclude that it is possible to characterize arterial wall function non-invasively in an adequately reproducible manner using a conventional ultrasound system in healthy middle-aged men and women.     

Evaluation of intima-media thickness and vascular elasticity of the common carotid artery in patients with isolated systolic hypertension using ultrasound radiofrequency-data technology

Background: Radiofrequency (RF) data technology is a newly developed method to evaluate vascular disease, especially subclinical atherosclerotic change. Data regarding predictors of intima‐media thickness (IMT) and vascular elasticity of the common carotid artery (CCA) in subjects with isolated systolic hypertension (ISH) using ultrasound RF‐data technology are scarce. Aims: We evaluated the change in IMT and vascular elasticity of the CCA in patients with ISH at an early phase using US RF‐data technology. Methods: Thirty‐nine patients with ISH and 41 age‐matched control subjects were the study population. The common carotid arterial systolic diameter (Ds), diastolic diameter (Dd), IMT, carotid distensibility (CD), local pulse wave velocity (PWVβ) and stiffness (β) were compared between the two groups, as were correlations between pulse pressure (PP) and parameters of vascular stiffness. Results: Common carotid arterial Ds, Dd, IMT, PWVβ and β increased whereas CD decreased more significantly in the ISH group than in age‐matched controls. The level of PP in the ISH group had significant positive correlations with PWVβ (r = 0·298, P<0·05) and β (r = 0·291, P<0·05), whereas significant correlations with CD were not observed. Conclusions: US RF‐data technology could be used to accurately and quantitatively evaluate increased IMT and decreased arterial elasticity of the CCA in patients with ISH compared with normal subjects.     

Right ventricular myocardial isovolumic relaxation time and pulmonary pressure

Aims: Non‐invasive assessment of pulmonary artery systolic pressure (PASP) has several limitations. As previously described by Burstin, the right ventricular (RV) isovolumic relaxation time (IVRt) is sensitive to changes in PASP. We therefore compared RV myocardial IVRt, derived by Doppler tissue imaging (DTI), with simultaneously measured invasive PASP. Methods and results: Twenty‐six consecutive patients (18 males, mean age 52 ± 12 years, range 23–75) underwent a simultaneous Doppler echocardiography, including DTI, and cardiac catheterization examination for measurement of PASP and right atrial mean pressures. IVRt was measured using the myocardial velocities by pulsed DTI at both basal and mid cavity segments of the RV free wall. As diastolic time intervals are influenced by heart rate IVRt was corrected for heart rate (IVRt/RR%). A significant correlation was found between PASP and regional IVRt/RR% at both the basal (r = 0·42, P<0·05) and mid cavity segment (r = 0·71, P<0·001). Furthermore, when only patients with normal right atrial pressures (<7 mmHg) were taken into account, the correlation coefficient improved at both basal and mid cavity segments (r = 0·74, P<0·05 and r = 0·83, P<0·01). Conclusion: Pulsed Doppler‐derived IVRt correlates well with PASP. The use of pulsed DTI for measurement of IVRt is simple, reproducible and easy to obtain. We propose this method as an additional non‐invasive tool in the assessment of PASP.     

高频超声对脑梗死患者颈动脉结构与功能改变的评价

目的应用高频超声研究脑梗死患者颈动脉血管结构与功能的改变。方法应用高频超声对46例脑梗死患者和40例健康老年人颈动脉行二维超声检查,观察并记录颈动脉内-中膜有无增厚、有无斑块、斑块数目和回声情况,测量舒张期内-中膜厚度(IMT);M-型超声记录颈总动脉前后壁在收缩期和舒张期运动幅度变化,测量舒张期和收缩期的内径,计算内-中膜横截面积(IMSCA)、僵硬度β指数、扩张性(distensibility)和顺应性(compliance)等参数。结果脑梗死患者比健康老年人斑块数目及低回声斑块检出率增加,最大IMT和平均IMT增厚,内-中膜横截面积、收缩期内径和舒张期内径、僵硬度指数增大,扩张性和顺应性降低(P<0.05)。IMT与僵硬度指数、扩张性和顺应性无明显相关性。IM-SCA、僵硬度指数、扩张性和顺应性与脉压相关(P<0.01),而与收缩压、舒张压等无明显相关性(P>0.05)。结论高频超声是无创诊断颈动脉早期动脉硬化的简便有效的方法,颈动脉IMT结合僵硬度、扩张性和顺应性等指标可反映脑梗死患者颈动脉血管结构和功能变化的特征,可提供更全面的信息。