Absolute Diameter Research Articles

Conceptual advantages of using pupil to limbus ratio over absolute pupil diameter.

Conceptual advantages of using pupil to limbus ratio over absolute pupil diameter.

Foliar and soil concentrations and stoichiometry of nitrogen and phosphorous across European Pinus sylvestris forests: relationships with climate, N deposition and tree growth

Summary This study investigated the factors underlying the variability of needle and soil elemental composition and stoichiometry and their relationships with growth in Pinus sylvestris forests throughout the species' distribution in Europe by analysing data from 2245 forest stands. Needle N concentrations and N:P ratios were positively correlated with total atmospheric N deposition, whereas needle P concentrations were negatively correlated. These relationships were especially pronounced at sites where high levels of N deposition coincided with both higher mean annual temperature and higher mean annual precipitation. Trends towards foliar P deficiency were thus more marked when high N deposition coincided with climatic conditions favourable to plant production. Atmospheric N deposition was positively correlated with soil solution , , K+, P and Ca2+ concentrations, the soil solution :P ratio, total soil N and the total soil N:Olsen P ratio and was negatively correlated with soil Olsen P concentration. Despite these nutrient imbalances, during the period studied (1990–2006), N deposition was positively related with Pinus sylvestris absolute basal diameter (BD) growth, although only accounting for the 10% of the total variance. However, neither N deposition nor needle N concentration was related with relative annual BD growth. In contrast, needle P concentration was positively related with both absolute and relative annual BD growth. These results thus indicate a tendency of European P. sylvestris forests to store N in trees and soil in response to N deposition and unveil a trend towards increased nutrient losses in run‐off as a consequence of higher soil solution N concentrations. Overall, the data show increasing ecosystem nutrient imbalances with increasingly limiting roles of P and other nutrients such as K in European P. sylvestris forests, especially in the centre of their distribution where higher levels of N deposition are observed. Thus, although the data show that N deposition has had an overall positive effect on P. sylvestris growth, the effect of continuous N deposition, associated with decreasing P and K and increasing N:P in leaves and in soil, may in the future become detrimental for the growth and competitive ability of P. sylvestris trees.

Risk of rupture or dissection in descending thoracic aortic aneurysm.

Current practice guidelines recommend surgical repair of large thoracic aortic aneurysms to prevent fatal aortic dissection or rupture, but limited natural history data exist to support clinical criteria for timely intervention. Of 3247 patients with thoracic aortic aneurysm registered in our institutional Thoracic Aortic Center Database, we identified and reviewed 257 nonsyndromic patients (age, 72.4±10.5 years; 143 female) with descending thoracic or thoracoabdominal aortic aneurysm without a history of aortic dissection in whom surgical intervention was not undertaken. The primary end point was a composite of aortic dissection/rupture and sudden death. Baseline mean maximal aortic diameter was 52.4±10.8 mm, with 103 patients having diameters ≥55 mm. During a median follow-up of 25.1 months (quartiles 1-3, 8.3-56.4 months), definite and possible aortic events occurred in 19 (7.4%) and 31 (12.1%) patients, respectively. On multivariable analyses, maximal aortic diameter at baseline emerged as the only significant predictor of aortic events (hazard ratio=1.12; 95% confidence interval, 1.08-1.15). Estimated rates of definite aortic events within 1 year were 5.5%, 7.2%, and 9.3% for aortic diameters of 50, 55, and 60 mm, respectively. Receiver-operating characteristic curves for discriminating aortic events were higher for indexed aortic sizes referenced by body size (area under the curve=0.832-0.889) but not significantly different from absolute maximal aortic diameter (area under the curve=0.805). Aortic size was the principal factor related to aortic events in unrepaired descending thoracic or thoracoabdominal aortic aneurysm. Although the risk of aortic events started to increase with a diameter >5.0 to 5.5 cm, it is uncertain whether repair of thoracic aortic aneurysms in this range leads to overall benefit, and the threshold for repair requires further evaluation.

Comparison of Cine-MRI and Transthoracic Echocardiography for the Assessment of Aortic Root Diameters in Patients with Suspected Marfan Syndrome

Patients with Marfan syndrome require repeated imaging for monitoring of aortic root aneurysms. Therefore, we evaluated the agreement and reproducibility of cine-MRI and echocardiography measurements of the sinuses of Valsalva in patients with suspected Marfan syndrome. 51 consecutive patients with suspected Marfan syndrome were prospectively examined using cine-MRI and echocardiography. Two readers independently measured aortic root diameters at the level of the sinuses of Valsalva in both cine-MRI and echocardiography. Statistics included intraclass correlation coefficient, Pearson correlation coefficient, Bland-Altman analysis, and two-sided t-test. In 38 of the 51 individuals (74.5 %), the diagnosis of Marfan syndrome was established according to the criteria of the Ghent-2 nosology. Cine-MRI measurements of the sinuses of Valsalva revealed a strong correlation with echocardiography (r = 0.929), but a statistically significant bias of -1.0 mm (p < 0.001). The mean absolute diameter for sinuses of Valsalva obtained by cine-MRI was 32.3 ± 5.8 mm as compared to 33.4 ± 5.4 mm obtained by echocardiography. Interobserver agreement of measurements of the sinuses of Valsalva was higher for cine-MRI than for echocardiography (p = 0.029). Despite small, but statistically significant differences in terms of agreement and reproducibility, cine-MRI and echocardiographic measurements of aortic root diameters provide comparable results without a significant clinical difference. Therefore both techniques may be used for monitoring of the aortic root in patients with Marfan syndrome.

Left Atrium Size in Elite Athletes

ObjectivesThe goal of this study was to perform a meta-analysis of the published literature to investigate the relationship of high levels of exercise training to left atrial (LA) size. BackgroundThe “athlete’s heart” is a series of cardiac adaptations to systematic exercise training and may include LA enlargement. MethodsWe conducted a systematic review of English-language studies in MEDLINE and Scopus from inception through April 29, 2014, that reported LA size in elite athletes. ResultsA total of 54 studies comprising 7,189 elite athletes and 1,375 controls were included. Forty-eight of the 54 studies reported absolute LA diameter in 7,018 athletes and 1,044 controls. Nine of the 54 studies (including 992 athletes and 426 controls) presented LA volume corrected for body surface area. The adjusted weighted mean LA diameter was 4.1 mm greater in athletes overall compared with sedentary controls (p < 0.0001), and LA volume index was 7.0 ml/m2 greater in athletes than controls (p < 0.01). Compared with controls, LA diameter was 4.6 mm greater in endurance-trained athletes (p < 0.0001), 2.9 mm greater in strength-trained athletes (p < 0.03), 3.5 mm greater in combined strength- and endurance-trained athletes (p < 0.0001), and 4.2 mm greater in athletes with unspecified training (p < 0.02). ConclusionsTo our knowledge, this is the largest compilation of studies documenting that elite athletes have larger LA dimensions compared with controls when evaluated by either LA diameter or LA volume corrected for body surface area. The largest average LA diameters were reported in endurance athletes. Physicians evaluating athletes should be aware that the LA is increased in both strength- and endurance-trained elite athletes.

A Pilot Study of Diagnostic Neuromuscular Ultrasound in Bell's Palsy.

Neuromuscular ultrasound of the cranial nerves is an emerging field which may help in the assessment of cranial neuropathies. The aim of this study was to evaluate the role of neuromuscular ultrasound in Bell's palsy. A second objective was to assess the possibility of any associated vagus nerve abnormality. Twenty healthy controls and 12 Bell's palsy patients were recruited. The bilateral facial nerves, vagus nerves, and frontalis muscles were scanned using an 18 MHz linear array transducer. Facial nerve diameter, vagus nerve cross-sectional area, and frontalis thickness were measured. Mean facial nerve diameter was .8 ± .2 mm in controls and 1.1 ± .3 mm in patients group. The facial nerve diameter was significantly larger in patients than controls (P = .006, 95% CI for the difference between groups of .12-.48), with a significant side-to-side difference in patients as well (P = .004, 95% CI for side-to-side difference of .08-.52). ROC curve analysis of the absolute facial nerve diameter revealed a sensitivity of 75% and a specificity of 70%. No significant differences in vagus nerve cross-sectional area or frontalis thickness were detected between patients and controls. Ultrasound can detect facial nerve enlargement in Bell's palsy and may have a role in assessment, or follow-up, of Bell's palsy and other facial nerve disorders. The low sensitivity of the current technique precludes its routine use for diagnosis, however, this study demonstrates its validity and potential for future research.

Agreement between inferior vena cava diameter measurements by subxiphoid versus transhepatic views.

Context:Correcting hypovolemia is extremely important. Central venous pressure measurement is often done to assess volume status. Measurement of inferior vena cava (IVC) is conventionally done in the subcostal view using ultrasonography. It may not be possible to obtain this view in all patients.Aims:We therefore evaluated the limits of agreement between the IVC diameter measurement and variation in subcostal and that by the lateral transhepatic view.Settings and Design:Prospective study in a tertiary care referral hospital intensive care unit.Subjects and Methods:After Institutional Ethics Committee approval and informed consent, we obtained 175 paired measurements of the IVC diameter and variation in both the views in adult mechanically ventilated patients. The measurements were carried out by experienced researchers. We then obtained the limits of agreement for minimum, maximum diameter, percentage variation of IVC in relation to respiration.Statistical Analysis Used:Bland–Altman's limits of agreement to get precision and bias.Results:The limits of agreement were wide for minimum and maximum IVC diameter with variation of as much as 4 mm in both directions. However, the limits of agreement were much narrower when the percentage variation in relation to respiration was plotted on the Bland–Altman plot.Conclusions:We conclude that when it is not possible to obtain the subcostal view, it is possible to use the lateral transhepatic view. However, using the percentage variation in IVC size is likely to be more reliable than the absolute diameter alone. It is possible to use both views interchangeably.

Should Tricuspid Annuloplasty be Performed With Pulmonary Valve Replacement for Pulmonary Regurgitation in Repaired Tetralogy of Fallot?

Indications for prophylactic tricuspid annuloplasty in patients with pulmonary regurgitation (PR) after tetralogy of Fallot (TOF) repair are unclear and often extrapolated from acquired functional tricuspid regurgitation (TR) data in adults, where despite correction of primary left heart pathology, progressive tricuspid annular dilation is noted beyond a threshold diameter >4 cm (21 mm/m(2)). We hypothesized that unlike in adult functional TR, in pure volume-overload conditions such as patients with PR after TOF, the tricuspid valve size is likely to regress after pulmonary valve replacement (PVR). A total of 43 consecutive patients who underwent PVR from 2005 until 2012 at a single institution were retrospectively reviewed. Absolute and indexed tricuspid annulus diameters (TADs), tricuspid annulus Z-scores, grade of TR along with right ventricular size, and function indices were recorded before and after PVR. Preoperative and postoperative echocardiographic data were available in all patients. A higher tricuspid valve Z-score correlated with greater TR both preoperatively (P = 0.005) and postoperatively (P = 0.02). Overall reductions in the absolute and indexed TAD and tricuspid valve Z-scores were seen postoperatively, with greater absolute as well as percentage reduction seen with larger preoperative TAD index (P = 0.007) and higher tricuspid annulus Z-scores (P = 0.06). In pure volume-overload conditions such as patients with PR after TOF, reduction in the tricuspid valve size is seen after PVR. Concomitant tricuspid annuloplasty should not be considered based on tricuspid annular dilation alone.

Echocardiographic Assessment of Centenary Patients

Background: Echocardiography is a diagnostic tool capable of detecting different parameters with the potential to assist the cardiologists in patients management. Being aware of these parameters in centenary patients may lead to greater understanding of the health/disease process in this population. Objectives: To evaluate echocardiographic parameters in centenary patients, since no study covering such data in that group was found in the literature. Methods: Sixteen centenary patients with low state of dependence and weakness and no history of heart disease were assessed by transthoracic echocardiography. Results: Diameters, areas, volumes and indexed left atrial volumes were found to be increased by 31.25%, 50%, 68.75% and 87.5% of patients, respectively. Absolute and indexed left ventricular diastolic diameters were found to be increased by 6.25% and 68.75%, respectively. Absolute and indexed left ventricular mass was increased by 37.5% and 75% of elderly patients. The study found that 62.5% of individuals presented a pattern of eccentric hypertrophy. Deficit of segmental contractility occurred in 31.25% of the sample. Pulmonary arterial systolic pressure above 40 mm Hg occurred in 61.5% of patients. Conclusion: Increased dimensions of left chambers and left ventricular mass especially when quantified by body surface point out to the need for indexing the values in these individuals. The presence of segmental deficit in 31.25% of patients suggests that silent ischemia is relatively common in centenarians. Pulmonary hypertension in 61.5% of patients without elevated pulmonary capillary pressure leads to suspected undiagnosed lung disease. (Arq Bras Cardiol: Imagem cardiovasc. 2015; 28(1):25-29)

ГЕОМЕТРИЧЕСКОЕ МОДЕЛИРОВАНИЕ ООЛОГИЧЕСКОЙ ВАРИАБЕЛЬНОСТИ У ВРАНОВЫХ ПТИЦ

We analyzed the egg shape in bird family Corvidae using a polynomial model and a compound ovoid model. We constructed a geometric model that reflects the relationship between cloacal and infundibular arcs, and the length and the diameter of the egg. Specifically, we quantified the shape of the egg via seven indices: the traditional index of elongation and six novel indices. Morphological parameters of bird eggs within three genera of Corvids (Corvus, Pica, and Garrulus) revealed that although there was overlap with their minimum and maximum values, the mean values remained different. Cluster analysis, using suggested indices and polynomial equations based on the absolute length and diameter of eggs, demonstrated different values within three main groups: the Hooded Crow, Carrion Crow, and Common Raven group, the European Jackdaw and Eurasian Jay group, and the Rook and Eurasian Magpie group. This is best explained by the variation in the elongation indices, suggesting that spheroid eggs are the optimal for clutches of 1-2 eggs or more than 5 eggs. Geometrical schemes, formulas of compound ovoid, and polynomial equations generated for seven species of corvids are supplied, which provide evidence of species-specific patterns of egg shapes.

Atenolol versus Losartan in Children and Young Adults with Marfan's Syndrome

BackgroundAortic-root dissection is the leading cause of death in Marfan's syndrome. Studies suggest that with regard to slowing aortic-root enlargement, losartan may be more effective than beta-blockers, the current standard therapy in most centers.MethodsWe conducted a randomized trial comparing losartan with atenolol in children and young adults with Marfan's syndrome. The primary outcome was the rate of aortic-root enlargement, expressed as the change in the maximum aortic-root-diameter z score indexed to body-surface area (hereafter, aortic-root z score) over a 3-year period. Secondary outcomes included the rate of change in the absolute diameter of the aortic root; the rate of change in aortic regurgitation; the time to aortic dissection, aortic-root surgery, or death; somatic growth; and the incidence of adverse events.ResultsFrom January 2007 through February 2011, a total of 21 clinical centers enrolled 608 participants, 6 months to 25 years of age (mean [±SD] age, 11.5±6.5 years in the atenolol group and 11.0±6.2 years in the losartan group), who had an aortic-root z score greater than 3.0. The baseline-adjusted rate of change in the mean (±SE) aortic-root z score did not differ significantly between the atenolol group and the losartan group (−0.139±0.013 and −0.107±0.013 standard-deviation units per year, respectively; P=0.08). Both slopes were significantly less than zero, indicating a decrease in the aortic-root diameter relative to body-surface area with either treatment. The 3-year rates of aortic-root surgery, aortic dissection, death, and a composite of these events did not differ significantly between the two treatment groups.ConclusionsAmong children and young adults with Marfan's syndrome who were randomly assigned to losartan or atenolol, we found no significant difference in the rate of aortic-root dilatation between the two treatment groups over a 3-year period. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT00429364.)

Energetic Implications of Vessel Growth and Flow Changes Over Time in Fontan Patients

As patients with a single-ventricle physiology age, long-term complications inherent to this population become more evident. Previous studies have focused on correlating anatomic and hemodynamic performance, but there is little information of how these variables change with time. Vessel growth and flow rate changes were quantified using cardiac magnetic resonance and their effects on hemodynamics were assessed, which could affect the long-term outcome. Forty-eight patients with a lateral tunnel or extracardiac conduit Fontan who underwent two cardiac magnetic resonance scans (average interval, 5.1 ± 2.3 years) were studied. Total cavopulmonary connection anatomic and flow variables were reconstructed and normalized to body surface area(1/2). Total cavopulmonary connection hemodynamic efficiency (indexed power loss) was obtained through computational fluid dynamic modeling. Absolute vessel diameters increased with time, normalized diameters decreased, and vessel mean flow rates remained unchanged. Indexed power loss changed significantly in the cohort, as well as in patients in whom the minimum normalized left pulmonary artery decreased. Age at first scan and connection type (lateral tunnel or extracardiac conduit) were not associated with changes in indexed power loss. We present the largest serial cardiac magnetic resonance Fontan cohort to date. Although flow rates increased proportionally to body surface area, vessel diameters did not match somatic growth. As a result, energy losses increased significantly with time in the cohort analyzed.

Determination of Particle Size Distributions, Molecular Weight Distributions, Swelling, Conformation, and Morphology of Dilute Suspensions of Cross-Linked Polymeric Nanoparticles via Size-Exclusion Chromatography/Differential Viscometry

Size-exclusion chromatography (SEC), coupled with differential viscometry detection (SEC/DV), is applied to the dilute suspension characterization of solvent-swollen cross-linked polymeric nanoparticles (PNPs). Cross-linked, unimolecular polymeric nanoparticles in the 5–50 nm weight-average diameter (dw) range were prepared by batch and semibatch microemulsion polymerization techniques and isolated. SEC and SEC/DV characterization techniques yield, based on the principle of universal calibration, a wealth of information regarding the structural attributes of PNPs, including apparent and absolute molecular weight distributions, apparent and absolute molecular weight averages, peak and weight-average particle diameters, particle size distributions in both the solvent-swollen and solvent-free states, particle conformation (shape), and an estimate of the volumetric swell factor. These structural parameters are critical to understanding PNP performance, and all are obtained in a single rapid chromatographic ex...

Normal Values of Aortic Root Dimensions in Healthy Adults

The reported ranges of aortic root (AR) diameters are limited by small sample size, different measurement sites, and heterogeneous cohorts. The aim of this study was to explore the full spectrum of AR diameters by 2-dimensional transthoracic color Doppler echocardiography (TTE) in a large cohort of healthy adults. From June 2007 to December 2013, a total of 1,043 Caucasian healthy volunteers (mean age 44.7 ± 15.9 years, range 16 to 92 years, 503 men [48%]) underwent comprehensive TTE. TTE measurements of the AR were made at end-diastole in parasternal long-axis views at 4 levels: (1) annulus, (2) sinuses of Valsalva, (3) sinotubular junction, and (4) proximal ascending aorta. The absolute aortic diameters were significantly greater in men than in women at all levels, whereas body surface area-indexed aortic diameters were greater in women (p = 0.0001). No significant gender differences were registered for sinuses of Valsalva and sinotubular junction to annulus diameter ratios (p = 0.9), whereas ascending aorta to annulus diameter ratio was higher in women (p = 0.0001). There was a straight correlation between aortic diameters (absolute and indexed values), their ratios, and age in both genders (p = 0.0001). In conclusion, we provide the full range of AR diameters by TTE. Knowledge of upper physiological limits of aortic dimensions is mandatory to detect aorta dilatation, follow up the disease over time, and plan appropriate therapeutic interventions.

Calibration-Free Coronary Artery Measurements for Interventional Device Sizing using Inverse Geometry X-ray Fluoroscopy: In Vivo Validation.

Proper sizing of interventional devices to match coronary vessel dimensions improves procedural efficiency and therapeutic outcomes. We have developed a novel method using inverse geometry x-ray fluoroscopy to automatically determine vessel dimensions without the need for magnification calibration or optimal views. To validate this method in vivo, we compared results to intravascular ultrasound (IVUS) and coronary computed tomography angiography (CCTA) in a healthy porcine model. Coronary angiography was performed using Scanning-Beam Digital X-ray (SBDX), an inverse geometry fluoroscopy system that performs multiplane digital x-ray tomosynthesis in real time. From a single frame, 3D reconstruction of the arteries was performed by localizing the depth of vessel lumen edges. The 3D model was used to directly calculate length and to determine the best imaging plane to use for diameter measurements, where out-of-plane blur was minimized and the known pixel spacing was used to obtain absolute vessel diameter. End-diastolic length and diameter measurements were compared to measurements from CCTA and IVUS, respectively. For vessel segment lengths measuring 6 mm to 73 mm by CCTA, the SBDX length error was -0.49 ± 1.76 mm (SBDX - CCTA, mean ± 1 SD). For vessel diameters measuring 2.1 mm to 3.6 mm by IVUS, the SBDX diameter error was 0.07 ± 0.27 mm (SBDX - minimum IVUS diameter, mean ± 1 SD). The in vivo agreement between SBDX-based vessel sizing and gold standard techniques supports the feasibility of calibration-free coronary vessel sizing using inverse geometry x-ray fluoroscopy.

Gender-related changes in aortic geometry throughout life

Aortic geometry changes throughout life are not well defined. This investigation delineates aortic geometry across the adult age spectrum and determines the gender-related influence of aging on aortic morphometry. Contrast-enhanced computed tomography scans of all aortic segments in 195 subjects (94 women, 101 men, average age 57 ± 20 years) free of vascular disease were analysed. Lengths and diameters of each aortic segment as well as width, height and tortuosity of the thoracic aorta were compared between both genders. Aortic diameters and lengths were larger in men than women (P < 0.001); however, after adjustment for body surface area (BSA), the ascending aorta and aortic arch revealed greater diameters in women than in men (P = 0.001 and P = 0.011, respectively). All aortic segment dimensions increased in a similar pattern with age for both genders, except the ascending aorta diameter, which increased +3.4% (P < 0.001) per decade in women and +2.6% (P < 0.001) per decade in men. Owing to more dynamic ascending aortic growth in women, absolute diameters were similar in both genders at an older age (>70 years old: 3.4 ± 0.3 vs 3.5 ± 0.3 cm, P = 0.241). Female gender is associated with smaller aortic dimensions, but only at a young age. The dynamics of aortic growth throughout life are greater in women than in men. Gender-related changes in aortic geometry provide a hypothesis for the predominance of aortic dissection in young male patients, which normalizes between genders with increasing age.

Pattern of Ascending Aortic Dimensions Predicts the Growth Rate of the Aorta in Patients With Bicuspid Aortic Valve

This study sought to identify risk factors for rapid growth of the ascending aorta in patients with bicuspid aortic valve (BAV) disease, taking into account its phenotypic variability. Phenotypic heterogeneity of BAV-related aortopathy has recently been widely recognized. However, few studies have addressed the determinants of aortic growth so far, not distinguishing among morphological phenotypes. Serial retrospective data on 133 adult outpatients with BAV undergoing echocardiographic follow-up were analyzed to search for factors associated with aortic diameter growth over time and with rapid aortic growth (fifth quintile of growth rate distribution), focusing on the impact of different valve morphotypes (i.e., cusp fusion pattern: right-left coronary [RL] and right-noncoronary [RN]) and previously defined aortic phenotypes (nondilated aorta, ascending dilation, root dilation). The RL pattern was present in 69% of patients with BAV and RN in 31%. At baseline, an ascending dilation phenotype was observed in 57% of patients and a root phenotype in 13.5%. No patient with RN-BAV had a root dilation phenotype at either baseline or last examination. Follow-up time averaged 4.0 ± 2.7 years (535 patient-years). The mean growth rate was 0.3 mm/year at the sinuses and 0.6 mm/year at the ascending level. Aortic regurgitation predicted an increase in ascending diameter over time (odds ratio [OR]: 2.3; p= 0.03). Root phenotype at presentation, not absolute baseline diameter, was an independent predictor of fast progression (>0.9 mm/year) for the ascending tract (OR: 14; p= 0.001). Fast growth was rarely seen in patients with the RL morphotype and ascending phenotype (6% at the root and 10% at the ascending level). In patients with BAV, the root phenotype (aortic dilation predominantly at the sinuses, with normal or less dilated ascending tract) may be a marker of more severe aortopathy, warranting closer surveillance and earlier treatment. The more common ascending phenotype proved to be a more stable disease entity, generally with slower progression.

Wall motion in the stenotic carotid artery: association with greyscale plaque characteristics, the degree of stenosis and cerebrovascular symptoms

BackgroundSystolic dilation of the atherosclerotic carotid artery depends on several factors including arterial compliance and the haemodynamic environment. The purpose of this study was to quantify wall motion in stenotic carotid arteries and investigate any associations with the ultrasound greyscale plaque characteristics, the degree of stenosis, and the presence of cerebrovascular symptoms.MethodsVariations in the lumen diameters of 61 stenotic carotid arteries (stenosis range 10%-95%) from 47 patients were measured before the proximal shoulder of the atherosclerotic plaque using ultrasound image sequences over several cardiac cycles. Absolute and percentage diameter changes from diastole to systole were calculated and their relationship to the degree of stenosis, greyscale plaque characteristics, and the presence of ipsilateral hemispheric symptoms were studied.ResultsThe mean absolute diameter change from diastole to systole was 0.45 mm (s.d. 0.17), and the mean percentage diameter change was 6.9% (s.d. 3.1%). Absolute and percentage diameter changes did not have a statistically significant relationship to the degree of stenosis, greyscale plaque characteristics, or the presence of ipsilateral hemispheric symptoms (p > 0.05). Parameters significantly correlated with the presence of symptoms were the degree of stenosis (p = 0.01), plaque greyscale median (p = 0.02) and the plaque surface irregularity index (p = 0.02).ConclusionsOur study confirmed the degree of stenosis, plaque greyscale median and our surface irregularity index were significant predictors of symptoms, but found no significant correlation between diameter changes of stenosed carotid arteries and the presence of ipsilateral hemispheric symptoms.

Interferometric diameter determination of a silicon sphere using a traceable single laser frequency synthesizer

To determine the absolute diameter of a silicon sphere for the Avogadro constant project, we present a phase-shifting interferometer based on a flat etalon and a traceable single laser frequency synthesizer. By using an optical frequency comb to calibrate a frequency-tunable diode laser, the single laser frequency synthesizer can produce an arbitrary laser frequency with a relative uncertainty of 9.2 × 10−12 in the range of 4 THz. According to the laser frequency tuning system, the Carré algorithm with arbitrary but equal phase steps is employed to calculate the fractional interference phases. The absolute diameter is obtained by measuring the fractional and integral parts based on the principles of phase-shifting interferometry and frequency-sweeping interferometry, respectively. The uncertainty of a single diameter measurement in air is estimated to be 5 nm, whose uncertainty sources from the laser frequency and the phase-shifting algorithm are negligible.

Knowledge, attitudes, and practice patterns in surgical management of bicuspid aortopathy: A survey of 100 cardiac surgeons

Clinical practice guidelines have been established for surgical management of the aorta in bicuspid aortic valve disease. We hypothesized that surgeons' knowledge of and attitudes toward bicuspid aortic valve aortopathy influence their surgical approaches. We surveyed cardiac surgeons to probe the knowledge of, attitudes toward, and surgical management of bicuspid aortopathy. A total of 100 Canadian adult cardiac surgeons participated. Fifty-two percent of surgeons believed that the mechanism underlying aortic dilation in those with bicuspid aortic valve was due to an inherent genetic abnormality of the aorta, whereas only 2% believed that altered valve-related processes were involved in this process. Only a minority (15%) believed that bicuspid valve leaflet fusion type is associated with a unique pattern of aortic dilatation aortic phenotype. Sixty-five percent of surgeons recommended echocardiographic screening of first-degree relatives of patients with bicuspid aortic valve. Most surgeons (61%) elected to replace the aorta when the diameter is 45 mm or greater at the time of valve surgery. Fifty-five percent of surgeons surveyed suggested that in the absence of concomitant valvular disease, they would recommend ascending aortic replacement at a threshold of 50 mm or greater. Approximately one third of surgeons suggested that they would elect to replace a mildly dilated ascending aorta (40 mm) at the time of valve surgery. The most common surgical approach (61%) for combined valve and aortic surgery was aortic valve replacement and supracoronary replacement of the ascending aorta, and only a minority suggested the use of deep hypothermic circulatory arrest and open distal anastomosis. More aggressive approaches were favored with greater surgeon experience, and when circulatory arrest was chosen, the majority (68%) suggested they would use antegrade cerebral perfusion. In the setting of aortic insufficiency and a dilated aorta, 42% of surgeons suggested that they would perform valve-sparing surgery. Of note, 40% of respondents used an index measure of aortic size to body surface area in addition to absolute aortic diameter in assessing the threshold for intervention. This large survey uncovered significant gaps in the knowledge and attitudes of surgeons toward the diagnosis and management of bicuspid aortopathy, many of which were at odds with current guideline recommendations. Efforts to promote knowledge translation in this area are strongly encouraged.