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Wall Thickness (wall + thickness)
Kinds of Wall Thickness Selected AbstractsThe Dependence of the Sensitivity and Reliability of Contactless Conductivity Detection on the Wall Thickness of Electrophoretic Fused-Silica CapillariesELECTROANALYSIS, Issue 3-5 2009Petr T Abstract A contactless conductivity detector (C4D) performance has been tested on a simple capillary electrophoretic separation in a standard fused-silica capillary with an external diameter of 360,,m and in a thin-walled capillary (an external diameter of 150,,m); the internal diameters of the two capillaries were identical, equal to 75,,m. Potassium and sodium ions have been separated in a morpholinoethanesulfonic acid/histidine background electrolyte (MES/His), over a wide range of its concentrations (0,100,mM). At low MES/His concentrations, the C4D response, obtained from the height of the potassium peak, is by 100 to 200 per cent higher for the thin-walled capillary and the calibration dependences are linear, in contrast to the thick-walled capillary. These differences between the two capillaries decrease with increasing MES/His concentration, the C4D response in the thin-walled capillary is then higher by mere 20 per cent and the calibration dependences are linear in both the capillaries. The highest sensitivities have been obtained at a MES/His concentration of 50,mM, with LOD values for potassium ion of 2.0 and 2.6,,M, in the thin- and thick-walled capillaries, respectively. The signal-to-noise ratios and the plate counts are generally similar for the two capillaries. It follows from the results that special thin-walled capillaries can be advantageous when background electrolytes with very low conductivities must be employed. [source] Formation of Nickel Oxide Nanotubes with Uniform Wall Thickness by Low-Temperature Thermal Oxidation Through Understanding the Limiting Effect of Vacancy Diffusion and the Kirkendall PhenomenonADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Yi Ren Abstract In this work, the step-wise oxidation mechanism of nickel (Ni) nanowires is elucidated. Rapid vacancy diffusion plays a significant role at low temperatures in forming heterostructures of nickel oxide (NiO) nanotubes with Ni nanowires. Subsequent investigations of Ni nanowire oxidation at higher temperatures and faster temperature ramp rates show that it is difficult to bypass this rapid vacancy diffusion stage, which affects the formation of the final structure. Therefore, it is unlikely to form solid NiO nanowires or NiO nanotubes with uniform wall thickness through the conventional annealing/oxidation process of Ni nanowires. Instead, a step-wise oxidation process by combining low temperature oxidation with a chemical etching step is utilized to produce for the first time NiO nanotubes with uniform wall thickness from Ni nanowires. [source] Novel Biomarkers for Diagnosis and Therapeutic Assessment of Overactive Bladder: Urinary Nerve Growth Factor and Detrusor Wall ThicknessLUTS, Issue 2009Hann-Chorng KUO Clinical diagnosis of overactive bladder (OAB) varies greatly and is based on subjective symptoms. A better way to diagnose and assess therapeutic outcome in patients who present with OAB needs to be developed. Evidence has shown that urinary proteins, such as nerve growth factor (NGF) and prostaglandin E2 (PGE2) levels increase in patients with OAB, bladder outlet obstruction (BOO) and detrusor overactivity (DO). Urinary NGF level increases physiologically in normal subjects at urge to void, but increases pathologically in OAB patients at small bladder volume and at urgency sensation. Patients with OAB dry and OAB wet have significantly higher urinary NGF levels compared to controls and patients with increased bladder sensation. Urinary NGF levels decrease after antimuscarinic therapy and further decrease after detrusor botulinum toxin injections in refractory OAB. A higher urinary NGF level could be a biomarker for sensory nerve-mediated DO. Urinary NGF levels could be a potential biomarker for diagnosis of OAB and serve for the assessment of the therapeutic effect of antimuscarinic therapy. Another potential biomarker for the diagnosis of OAB is detrusor wall thickness. It has been hypothesized that the bladder wall increases in thickness in patients with OAB. The thickened detrusor wall might decrease in response to antimuscarinic treatment, and measurement of detrusor wall thickness might be a useful biomarker for the evaluation of OAB. However, current investigations do not yet provide a uniform observation among various studies. [source] Menopause Leading to Increased Vaginal Wall Thickness in Women with Genital Prolapse: Impact on Sexual ResponseTHE JOURNAL OF SEXUAL MEDICINE, Issue 11 2009Lúcia Alves Da Silva Lara MD ABSTRACT Introduction., Hypoestrogenism causes structural changes in the vaginal wall that can lead to sexual dysfunction. A reduction in vaginal wall thickness has been reported to occur after menopause, although without precise morphometry. Aim., To measure vaginal wall thickness in women with genital prolapse in normal and hypoestrogenic conditions and to correlate sexual dysfunction with vaginal wall thickness and estradiol levels. Methods., Surgical vaginal specimens from 18 normoestrogenic and 13 postmenopausal women submitted to surgery for genital prolapse grades I and II were examined. Patients were evaluated for FSH, estradiol, prolactin, glycemia, and serum TSH levels. For histological analysis, samples were stained with Masson's trichrome and hematoxylin-eosin. Sexual function was assessed by the Golombok-Rust Inventory of Sexual Satisfaction (GRISS). Main Outcome Measures., GRISS questionnaire, histological analysis, morphometric methods, Masson's trichrome. Results., The vaginal wall was thicker in the postmenopausal than premenopausal group (2.72 ± 0.72 mm and 2.16 ± 0.43, P = 0.01, and 2.63 ± 0.71 mm and 2.07 ± 0.49 mm, P = 0.01, for the anterior and posterior walls, respectively). These thicknesses seem to be due to the muscular layer, which was also thicker in the postmenopausal group (1.54 ± 0.44 and 1.09 ± 0.3 mm, P = 0.02, and 1.45 ± 0.47 and 1.07 ± 0.44 mm, P = 0.03, for the anterior and posterior wall, respectively). The vaginal epithelium was thinner in the middle segment than in the proximal one in the posterior wall (0.17 ± 0.07 mm, 0.15 ± 0.05 mm, 0.24 ± 0.09 mm, P = 0.02). There was no correlation between coital pain, vaginal wall thickness, and estradiol levels in either group. Conclusion., The vaginal wall is thicker after menopause in women with genital prolapse. In this study, vaginal thickness and estrogen levels were not related to sexual dysfunction. da Silva Lara LA, Ribeiro-Silva A, Rosa-e-Silva JC, Chaud F, Silva-de-Sá MF, Meireles e Silva AR, and Rosa-e-Silva ACJS. Menopause leading to increased vaginal wall thickness in women with genital prolapse: impact on sexual response. J Sex Med 2009;6:3097,3110. [source] Outcome in Cardiac Recipients of Donor Hearts With Increased Left Ventricular Wall ThicknessAMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2007S. S. Kuppahally The ongoing shortage of donors for cardiac transplantation has led to a trend toward acceptance of donor hearts with some structural abnormalities including left ventricular hypertrophy. To evaluate the outcome in recipients of donor hearts with increased left ventricular wall thickness (LVWT), we retrospectively analyzed data for 157 cardiac donors and respective recipients from January 2001 to December 2004. There were 47 recipients of donor heart with increased LVWT ,1.2 cm, which constituted the study group and 110 recipients of a donor heart with normal LVWT < 1.2 cm that formed the control group. At 3 ± 1.5 years, recipient survival was lower (50% vs. 82%, p = 0.0053) and incidence of allograft vasculopathy was higher (50% vs. 22%, p = 0.05) in recipients of donor heart with LVWT > 1.4 cm as compared to LVWT , 1.4 cm. By Cox regression, donor LVWT > 1.4 cm (p = 0.003), recipient preoperative ventricular assist device (VAD) support (p = 0.04) and bypass time > 150 min (p = 0.05) were predictors of reduced survival. Our results suggest careful consideration of donor hearts with echocardiographic evidence of increased LVWT in the absence of hypovolemia, because they may be associated with poorer outcomes; such hearts should potentially be reserved only for the most desperately ill recipients. [source] Hollow Inorganic Nanospheres and Nanotubes with Tunable Wall Thicknesses by Atomic Layer Deposition on Self-Assembled Polymeric Templates,ADVANCED MATERIALS, Issue 1 2007The construction of inorganic nanostructures with hollow interiors is demonstrated by coating self-assembled polymeric nano-objects with a thin Al2O3 layer by atomic layer deposition (ALD), followed by removal of the polymer template upon heating. The morphology of the nano-object (i.e., spherical or cylindrical) is controlled by the block lengths of the copolymer. The thickness of the Al2O3 wall is controlled by the number of ALD cycles. [source] Reentry in a Morphologically Realistic Atrial ModelJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2001EDWARD J. VIGMOND Ph.D. Reentry in Morphologically Realistic Atria.Introduction: Atrial fibrillation is the most common cardiac arrhythmia. In ablation procedures, identification of the reentrant pathways is vital. This has proven difficult because of the complex morphology of the atria. The purpose of this study was to ascertain the role of specific anatomic structures on reentry induction and maintenance. Method and Results: A computationally efficient, morphologically realistic, computer model of the atria was developed that incorporates its major structural features, including discrete electrical connections between the right and left atria, physiologic fiber orientation in three dimensions, muscle structures representing the crista terminalis (CT) and pectinate muscles, and openings for the veins and AV valves. Reentries were induced near the venous openings in the left and right atria, the mouth of the coronary sinus, and the free wall of the right atrium. The roles of certain muscular structures were ascertained by selectively removing the structures and observing how the propagation of activity was affected. Conclusion: (1) The muscular sheath of the coronary sinus acts as a pathway for a reentrant circuit and stabilizes any circuits that utilize the isthmus near the inferior vena cava. (2) Poor trans-CT coupling serves to stabilize flutter circuits. (3) Wall thickness is an important factor in the propagation of electrical activity, especially in the left atrium. (4) The openings of the inferior and superior venae cavae form natural anatomic anchors that make reentry easier to initiate by allowing for smaller ectopic beats to induce reentry. [source] Diagnostic utility of brain-natriuretic peptide for left ventricular diastolic dysfunction in asymptomatic type 2 diabetic patientsDIABETES OBESITY & METABOLISM, Issue 3 2007M. Shimabukuro Aim:, Left ventricular (LV) diastolic dysfunction has been reported to be prevalent in diabetic subjects, but this recognition could often be missed. We evaluated prevalence of LV diastolic dysfunction and diagnostic utility of brain-natriuretic peptide (BNP) in asymptomatic patients with type 2 diabetes mellitus. Research design and methods:, Plasma BNP levels and LV geometry and diastolic filling indices, including the ratio of peak early transmitral Doppler flow (E) over flow propagation velocity (Vp) measured by colour M-mode Doppler echocardiography, were analysed in 98 consecutive asymptomatic patients with type 2 diabetes mellitus and 51 age-matched controls. Results:, The LV mass index and relative wall thickness were higher in diabetic groups than controls without any differences in LV systolic function. The frequency of diastolic dysfunction defined as E/Vp , 1.5 were 31% in diabetic groups and 15% in controls (,2 = 4.364, p = 0.037). By receiver-operating characteristic (ROC) curve analysis, a BNP cutoff value of 19.2 pg/ml in controls had a 53.1% positive predictive value (53.1%) and a high negative predictive value (94.4%) for E/Vp , 1.5, whereas a BNP cutoff value of 18.1 pg/ml in diabetic groups had a 61.8% positive and 97.3% negative predictive values. Conclusions:, The frequency of E/Vp , 1.5 was higher in asymptomatic diabetic patients, suggesting that LV diastolic dysfunction was prevalent. The plasma concentration of BNP could be used to depict LV diastolic dysfunction in such population. [source] Baseline Echocardiographic Predictors of Dynamic Intraventricular Obstruction of the Left Ventricle during Dobutamine Stress EchocardiogramECHOCARDIOGRAPHY, Issue 10 2009Edmundo Jose Nassri Câmara M.D., Ph.D. Background: Intraventricular obstruction (IVO) during dobutamine stress echocardiogram (DSE) may be associated with or reproduce symptoms. Predictors of IVO are not well established. Methods: 149 patients were studied at rest and during DSE. The normal range of the left ventricular outflow tract (LVOT) velocities was investigated in 68 healthy patients. Results: 19 patients (13%) developed IVO (peak LVOT velocity > 271 cm/sec). A significant linear correlation was observed between peak LVOT velocity during DSE and the following rest parameters: LV end-diastolic dimension (r =,0.20, P = 0.018), LV end-systolic dimension (r =, 0.27, P = 0.001), relative wall thickness (r = 0.23, P = 0.006), shortening fraction (r = 0.24, P = 0.004), LVOT diameter (r =, 0.20, P = 0.023) and LVOT velocity (r = 0.29, P < 0.0001). Only relative wall thickness (P = 0.012) and LVOT diameter (P = 0.027) were independent predictors of IVO. As a dichotomous variable, a relative wall thickness ,0.44 was the only independent predictor of IVO (OR 5.7, 95% CI 1.6,20, P = 0.006), with sensitivity, specificity, negative predictive value, and positive predictive value of 77%, 62%, 95%, and 21%, respectively, and global accuracy of 63% (area under the ROC curve = 0.7). IVO was significantly associated with general cardiovascular symptoms (P = 0.0006) and with chest pain (P = 0.008). Conclusions: Relative wall thickness and LVOT diameter were independent predictors of obstruction. As a dichotomous variable, a relative wall thickness , 0.44 was the only independent predictor of dynamic IVO. [source] The Effects of Antihypertensive Treatment on the Doppler-Derived Myocardial Performance Index in Patients with Hypertensive Left Ventricular Hypertrophy: Results from the Swedish Irbesartan in Left Ventricular Hypertrophy Investigation Versus Atenolol (SILVHIA)ECHOCARDIOGRAPHY, Issue 7 2009Stefan Liljedahl M.D. Objectives: To investigate the effects of antihypertensive treatment on the Doppler-derived myocardial performance index (MPI) in patients with hypertensive left ventricular hypertrophy. Methods: The MPI was measured at baseline and after 48 weeks of antihypertensive treatment in 93 participants of the SILVHIA trial, where individuals with primary hypertension and left ventricular hypertrophy were randomized to double blind treatment with either irbesartan or atenolol. Results: Antihypertensive treatment lowered MPI (mean difference ,0.03 ± 0.01, P = 0.04). Changes in MPI by treatment were associated with changes in left ventricular ejection fraction (,-coefficient ,0.35 P = 0.005), stroke volume/pulse pressure (reflecting arterial compliance, ,-coefficient ,0.39 P < 0.001) and peripheral vascular resistance (,-coefficient 0.28 P < 0.04). Furthermore, there was a borderline significant association between changes in MPI and changes in E-wave deceleration time (reflecting diastolic function, ,-coefficient 0.23, P = 0.06). No associations were found between changes in MPI and changes in blood pressure, E/A-ratio, left ventricular mass index, relative wall thickness or heart rate. A stepwise multivariable regression model confirmed the association between changes in MPI and changes in ejection fraction and stroke volume/pulse pressure (all P < 0.05), as well as the trend for E-wave deceleration time (P = 0.08), but not in the case of peripheral vascular resistance. Conclusion: The MPI exhibited a modest decrease after 48 weeks of antihypertensive treatment in patients with hypertensive left ventricular hypertrophy. Changes in MPI were associated with changes in left ventricular function and vascular compliance, rather than with changes in left ventricular remodeling or blood pressure. [source] Echocardiographic Left Ventricular Mass in a Multiethnic Southeast Asian Population: Proposed New Gender and Age-Specific NormsECHOCARDIOGRAPHY, Issue 8 2008M.R.C.P., Raymond Ching-Chiew Wong M.B.B.S. Background: Left ventricular mass (LVM) is an independent risk factor for cardiovascular outcome. We aimed to define normal reference values of LVM/body surface area (BSA) in a multiethnic Southeast Asian population across ages, and define demographic parameters that predict LVM/BSA. Methods: 198 subjects (44% men, mean age 40 ± 14 years, 82% Chinese, 13% Malay and 5% Indian) with no cardiovascular comorbidity and had normal echo images for age were included in the analysis. Echo LVM was calculated as: 1.04 ×[(left ventricular internal diameter at end-diastole {LVIDd}+ interventricular septal thickness at end-diastole {IVSd}+ left ventricular posterior wall thickness at end-diastole {LVPWd})3, LVIDd3× 0.8]+ 0.61, indexed by BSA (LVM/BSA)* and expressed as g/m2. Results: BSA and blood pressure (BP) were comparable between dichotomous age groups < or , 50 years within the same gender. Women aged , 50 years had larger IVSD, LVPWd, LVM and LVM/BSA compared to younger cohort. (p < 0.01 for all variables). The 95th percentile of LVM in men and women were 189 g and 148 g respectively; corresponding values for LVM/BSA were 106 and 96 g/m2. These values are consistently smaller than published values from the West. Age (r = 0.27, P < 0.001), gender (r =,0.30, P < 0.001), and systolic BP (r = 0.25, P = 0.003) were significant univariate predictors of LVM/BSA. Conclusion: We therefore propose a different cutoff value for the diagnosis of LV hypertrophy among Southeast Asians. [source] Two- and Three-Dimensional Transthoracic Echocardiographic Assessment of Hiatal HerniaECHOCARDIOGRAPHY, Issue 7 2008Mohit Gupta M.D. Using two- (2DTTE) and three-dimensional transthoracic echocardiography (3DTTE) and an oral contrast agent (a carbonated beverage), a mass-like lesion behind the left ventricular posterior wall in an elderly female was definitively diagnosed as a hiatal hernia. A 3DTTE provided a more comprehensive evaluation of the hiatal hernia as compared to the 2DTTE in terms of its size and extent and thickness of the wall. The size of the hernia was underestimated by 2DTTE (3.3 × 3.2 cm) as compared to 3DTTE (at least 7 × 4.8 cm). The maximum thickness of the gastric wall was also found to be larger by 3DTTE (11 mm) as compared to 2DTTE (5 mm). Both the size of the hernia and thickness of the wall have important clinical implications. The size has been reported to be the strongest predictor of severity of esophagitis and gastric wall thickness of 10 mm or more has been associated with malignant or potentially malignant gastric lesions. [source] Relationship between Relative Aerobic Power and Echocardiographic Characteristics in Male AthletesECHOCARDIOGRAPHY, Issue 9 2007Zsuzsanna Kneffel M.Ed. The relationship between relative aerobic power (rel.VO2max) as a generally accepted indicator of endurance capacity and certain characteristics of the athlete's heart, such as body-size related (relative) left ventricular (LV) diastolic wall thickness (WTd), internal diameter (LVIDd), muscle mass (MM), WTd/IDd, heart rate (HR), fractional shortening (FS) and E/A ratio, were investigated in 346 young males (18,35 years, 291 athletes of various events and 55 nonathletic control subjects). Rel.VO2max was measured by spiroergometry; cardiac characteristics were determined by two-dimensionally guided M-mode and Doppler-echocardiography. When the groups were pooled, correlation of rel.VO2max with the cardiac parameters was significant: LVMM·BSA,1.5= 0.413, LVWTd·BSA,0.5= 0.327, LVIDd·BSA,0.5= 0.292, HR =,0.434, E/A = 0.272 (P < 0.001), but no significant relationship was seen with FS and WTd/IDd. In the endurance trained group, rel. VO2max correlated significantly with LVMM·BSA,1.5, LVWT·BSA,0.5, HR, and E/A, in the ballgame players with LVMM·BSA,1.5, LVWT·BSA,0.5, and E/A, in the power-and-sprint event athletes with HR and E/A. In the control group, no significant relationship was observed. Results indicate that in athletes having higher endurance capacity maximal oxygen consumption depends largely on cardiac condition, while in athletes with a lower endurance capacity it can be limited by peripheral conditions. [source] A Pilot Study of the Clinical Impact of Hand-Carried Cardiac Ultrasound in the Medical ClinicECHOCARDIOGRAPHY, Issue 6 2006Lori B. Croft M.D. Background: Small, hand-carried ultrasound devices have become widely available, making point-of-care echocardiograms (echos) accessible to all medical personnel as a means to augment and improve the increasingly inefficient physical examination. This study was designed to determine the clinical utility of hand-carried echo by medical residents in clinical decision making. Methods: Nine residents underwent brief, practical echo training to perform and interpret a limited hand-carried echo as an integral component of their office examination. The residents' hand-carried echo consisting of four basic views to define left ventricular (LV) function and wall thickness, valvular disease, and any pericardial effusions was compared to one performed by a level III echocardiographer. Results: Seventy-two consecutive medical clinic patients were enrolled with an average image acquisition time of 4.45 minutes. Residents obtained diagnostic images in 94% of the cases and interpreted them correctly 93% of the time. They correctly identified 92% of the major echo findings and 78% of the minor findings. Their diagnosis of LV dysfunction, valvular disease, and LV hypertrophy improved by 19%, 39%, and 14% with hand-carried echo compared to history and physical alone. Management decisions were reinforced in 76% and changed in 40% of patients with the use of hand-carried echo. Conclusion: This study demonstrates that it is possible to train medical residents to perform an effective and reasonably accurate hand-carried echo during their physical examination, which can impact clinical management. [source] Hepatopulmonary Syndrome and Right Ventricular Diastolic Functions: An Echocardiographic ExaminationECHOCARDIOGRAPHY, Issue 4 2006Aziz Karabulut M.D. Aim: Liver functions are affected in the course of cardiac diseases, and similarly, liver diseases affect cardiac functions. Many studies in the literature have shown that left ventricular systolic and/or diastolic dysfunction may develop during chronic liver disease. However, there are limited studies investigating right ventricular functions during chronic liver diseases. Methods: A total of 84 patients who had no systolic and/or diastolic dysfunction in the left ventricle (LV) were evaluated; 46 patients with liver cirrhosis; 10 (21.74%) cirrhotic patients with hepatopulmonary syndrome (HPS) (group 1), 36 (78.26) cirrhotic patients without HPS (group 2), and 38 healthy individuals were treated as control. Results: Right ventricular diastolic dysfunction was determined in all patients of group 1 (100%), 26 of group 2 (72.22 %), and 4 of the controls (10.52%) (P < 0.05). Tricuspid deceleration time (dt) was significantly different between the groups (P < 0.05). In addition, right atrium (RA) diameters, right ventricle (RV) diameters, and RV wall thickness were significantly different between the groups (P < 0.05). Pulmonary artery pressure (P < 0.05) and pulmonary vascular resistance (P < 0.05) were also seen to be higher in group 1 than those in group 2 and control group. Conclusions: Right ventricular diastolic dysfunction rate is high in chronic liver diseases. In the presence of HPS, right ventricular diastolic dysfunction is more remarkable in patients than those without HPS. Right ventricular diastolic dysfunction may result in dilatation and hypertrophy in the right heart. [source] Quantitative Evaluation of Left Ventricle Performance from Two Dimensional Echo ImagesECHOCARDIOGRAPHY, Issue 2 2006J. Manivannan M.E. Objectives: We sought to quantify the left ventricle systolic dysfunction by a geometric index from two-dimensional (2D) echocardiography by implementing an automated fuzzy logic edge detection algorithm for the segmentation. Background: The coronary injuries have repercussions on the left ventricle producing changes on wall contractility, the shape of the cavity, and as a whole changes on the ventricular function. Methods: 2D echocardiogram and M-mode recordings were performed over the control group and those with the dysfunctions. From 2D recordings, individual frames were extracted for at least five cardiac cycles and then segmentation of left ventricle was done by automated fuzzy systems. In each frame, the volumes are measured and a geometric index, eccentricity ratio (ER), was derived. The endocardial fractional shortening (FS), midwall fractional shortening (mFS), and the relative wall thickness (RWT) were also measured in each case. Results: Depressed value of endocardial FS (20.39 ± 5.43 vs 34.28 ± 9.36, P = 0.0046), mFS (33 ± 8.3 vs 52.5 ± 11.7, P = 0.0047), and the RWT (0.337 ± 0.096 vs 0.525 ± 0.119, P = 0.0002) was observed with dysfunction. ER measured at end-diastole (2.86 ± 0.703 vs 4.14 ± 0.38) and end-systole (3.14 ± 0.79 vs 5.48 ± 0.74) was found to be decreased in the dysfunction group and more significant at the end-systole (P = 0.00017 vs 6.6E,06). Conclusion: This work concludes that the regional and global left ventricle systolic dysfunction can be assessed by the ER measured at end-diastole and end-systole from 2D echocardiogram and may contribute to the high rate of cardiovascular disorders. [source] An Echocardiographic Analysis of the Long-Term Effects of Carvedilol on Left Ventricular Remodeling, Systolic Performance, and Ventricular Filling Patterns in Dilated CardiomyopathyECHOCARDIOGRAPHY, Issue 7 2005Peter S. Rahko M.D. Background: The long-term clinical benefit of beta blockade is well recognized, but data quantifying long-term effects of beta blockade on remodeling of the left ventricle (LV) is limited. Methods: This consecutive series evaluates the long-term response of the LV to the addition of carvedilol to conventional therapy for dilated cardiomyopathy. There were 33 patients who had a LV ejection fraction <45%, LV enlargement and symptomatic heart failure. Quantitative Doppler echocardiography was performed at baseline 6, 12, 24, and 36 months after initiation of carvedilol to evaluate LV ejection fraction, LV volume, wall stress, mass, regional function, and diastolic performance. Results: Compared to baseline there was a significant and sustained reduction in end-systolic volume and end-systolic wall stress with a corresponding improvement in LV ejection fraction. The LV mass did not decline but relative wall thickness increased toward normal. An analysis of regional wall motion responses showed an improvement in all areas, particularly the apical, septal, and lateral walls that was significantly more frequent in patients with a nonischemic etiology. Filling patterns of the LV remained abnormal throughout the study but changed with therapy suggesting a decline in filling pressures. These changes were sustained for 3 years. Conclusion: (1) The addition of carvedilol to conventional therapy for a dilated cardiomyopathy significantly improves LV ejection fraction and reduces LV end-systolic volume and wall stress for at least 3 years, (2) the response to 6 months of treatment predicts the long-term response, (3) the typical response is partial improvement of the LV, complete return to normal size, and function is uncommon, and (4) abnormalities of LV filling persist in virtually all patients throughout the course of treatment. [source] Catheterization,Doppler Discrepancies in Nonsimultaneous Evaluations of Aortic StenosisECHOCARDIOGRAPHY, Issue 5 2005Payam Aghassi M.D. Prior validation studies have established that simultaneously measured catheter (cath) and Doppler mean pressure gradients (MPG) correlate closely in evaluation of aortic stenosis (AS). In clinical practice, however, cath and Doppler are rarely performed simultaneously; which may lead to discrepant results. Accordingly, our aim was to ascertain agreement between these methods and investigate factors associated with discrepant results. We reviewed findings in 100 consecutive evaluations for AS performed in 97 patients (mean age 72 ± 10 yr) in which cath and Doppler were performed within 6 weeks. We recorded MPG, aortic valve area (AVA), cardiac output, and ejection fraction (EF) by both methods. Aortic root diameter, left ventricular end-diastolic dimension (LVIDd) and posterior wall thickness (PWT) were measured by echocardiography and gender, heart rate, and heart rhythm were also recorded. An MPG discrepancy was defined as an intrapatient difference > 10 mmHg. Mean pressure gradients by cath and Doppler were 36 ± 22 mmHg and 37 ± 20 mmHg, respectively (P = 0.73). Linear regression showed good correlation (r = 0.82) between the techniques. An MPG discrepancy was found in 36 (36%) of 100 evaluations; in 19 (53%) of 36 evaluations MPG by Doppler was higher than cath, and in 17 (47%) of 36, it was lower. In 33 evaluations, EF differed by >10% between techniques. Linear regression analyses revealed that EF difference between studies was a significant predictor of MPG discrepancy (P = 0.004). Women had significantly higher MPG than men by both cath and Doppler (43 ± 25 mmHg versus 29 ± 15 mmHg [P = 0.001]; 42 ± 23 mmHg versus 32 ± 15 mmHg [P = 0.014], respectively). Women exhibited discrepant results in 23 (47%) of 49 evaluations versus 13 (25%) of 51 evaluations in men (P = 0.037). After adjustment for women's higher MPG, there was no statistically significant difference in MPG discrepancy between genders (P = 0.22). No significant interactions between MPG and aortic root diameter, relative wall thickness (RWT), heart rate, heart rhythm, cardiac output, and time interval between studies were found. In clinical practice, significant discrepancies in MPG were common when cath and Doppler are performed nonsimultaneously. No systematic bias was observed and Doppler results were as likely yield lower as higher MPGs than cath. EF difference was a significant predictor of discrepant MPG. Aortic root diameter, relative wall thickness, heart rate, heart rhythm, cardiac output, presence or severity of coronary artery disease, and time interval between studies were not predictors of discrepant results. [source] Impact of Body Mass Index on Markers of Left Ventricular Thickness and Mass Calculation: Results of a Pilot AnalysisECHOCARDIOGRAPHY, Issue 3 2005Ranjini Krishnan M.D. Specific correlations between body mass index (BMI) and left ventricular (LV) thickness have been conflicting. Accordingly, we investigated if a particular correlation exists between BMI and echocardiographic markers of ventricular function. Methods: A total of 122 patients, referred for routine transthoracic echocardiography, were included in this prospective pilot study using a 3:1 randomization approach. Patient demographics were obtained using a questionnaire. Results: Group I consisted of 80 obese (BMI was >30 kg/m2), Group II of 16 overweight (BMI between 26 and 29 kg/m2), and Group III of 26 normal BMI (BMI < 25 kg/m2) individuals. No difference was found in left ventricular wall thickness, LV end-systolic cavity dimension, fractional shortening (FS), or pulmonary artery systolic pressure (PASP) among the groups. However, mean LV end-diastolic cavity dimension was greater in Group I (5.0 ± 0.9 cm) than Group II (4.6 ± 0.8 cm) or Group III (4.4 ± 0.9 cm; P < 0.006). LV mass indexed to height2.7 was also significantly larger in Group I (61 ± 21) when compared to Group III (48 ± 19; P < 0.001). Finally, left atrial diameter (4.3 ± 0.7 cm) was also larger (3.8 ± 0.6 and 3.6 ± 0.7, respectively; P < 0.00001).Discussion: We found no correlation between BMI and LV wall thickness, FS, or PASP despite the high prevalence of diabetes and hypertension in obese individuals. However, obese individuals had an increased LV end-diastolic cavity dimension, LV mass/height2.7, and left atrial diameter. These findings could represent early markers in the sequence of cardiac events occurring with obesity. A larger prospective study is needed to further define the sequence of cardiac abnormalities occurring with increasing BMI. [source] Echocardiographic Left Ventricular Mass in African-AmericansECHOCARDIOGRAPHY, Issue 2 2003The Jackson Cohort of the Atherosclerosis Risk in Communities Study Characterization of target organ damage from hypertension is of particular interest in African-Americans, and evidence from electrocardiographic studies suggests that left ventricular hypertrophy is a frequent clinical finding of considerable prognostic importance. Echocardiographic studies may permit more precise characterization of the pathologic impact of hypertension on cardiac structure and function. The objective of this study is to characterize left ventricular (LV) structure including measures of wall thickness, septal thickness, internal dimension, and mass in a middle-aged sample of African-Americans using echocardiography. This study is a cohort (cross-sectional) study in which 2445 middle-aged African-American study participants from a population-based sample initially enrolled by the Atherosclerosis Risk in Communities, Jackson, Mississippi Examination Center in 1987,1989 underwent an M-mode echocardiograpic examination at their third or fourth clinic visit in 1993,1996. Measures of LV mass, even where indexed by size were conspicuously greater in men compared to women, and men exhibited a demonstrably steeper gradient of LV mass across the rather restricted age range of the study. However, when gender specific thresholds for LV hypertrophy were utilized, African-American men appear to have lower prevalence of LV hypertrophy than women. The lowest prevalence of LV hypertrophy was observed in African-American men who did not have hypertension (28.4%). The findings confirm previous suggestions from electrocardiographic investigations that cardiac hypertrophy is common, if not epidemic in middle-aged African-American men and women, whether or not they have hypertension. (ECHOCARDIOGRAPHY, Volume 20, February 2003) [source] Is Left Ventricular Diastolic Thickening Documented During Dobutamine and Pacing Stress Echocardiography Related to Myocardial Ischemia?ECHOCARDIOGRAPHY, Issue 1 2002An Animal Model Study Transient increase in diastolic wall thickness (pseudohypertrophy) during pacing stress echocardiography has been reported in normal myocardium. To evaluate the occurrence of pseudohypertrophy and to investigate the contribution of myocardial ischemia on its production during pacing and dobutamine stress echocardiography, we produced a physiologically significant coronary stenosis in 14 open chest dogs. The stenosis in the circumflex artery was measured by quantitative coronary angiography (range: 50% to 89% reduction in luminal diameter), and no resting segmental wallmotion abnormalities were observed by epicardial echocardiography (short-axis, papillary level). In each study, dobutamine (5,40 ,g/kg/min) and pacing (up to 260 beats/min) were performed randomly. Positivity of stress echocardiography tests was quantitatively determined by a significant (P < 0.05) reduction or failure to increase in absolute and percent systolic wall thickening in the myocardial area supplied by the stenotic artery as compared to the left anterior descending (LAD) artery-related areas. Diastolic wall thickness and left ventricular diastolic area were compared before and after each stress test in the circumflex and LAD artery-related regions. Pseudohypertrophy was observed in 57% and 86% of dogs for pacing and dobutamine, respectively, in the circumflex region, and in 50% and 64% in the LAD region. Despite its increased incidence in the circumflex region, the augmented diastolic wall thickness did not correlate with coronary stenosis severity or stress test positivity, but correlated inversely with changes in left ventricular diastolic area. In addition, it correlated directly with changes in heart rate only for pacing. In conclusion, pseudohypertrophy was a frequent finding during pacing and dobutamine stress echocardiography tests but was not related to myocardial ischemia in this animal model. [source] Role of Transthoracic Echocardiography in Atrial FibrillationECHOCARDIOGRAPHY, Issue 4 2000RICHARD W. ASINGER M.D. Atrial fibrillation is a major clinical problem that is predicted to be encountered more frequently as the population ages. The clinical management of atrial fibrillation has become increasingly complex as new therapies and strategies have become available for ventricular rate control, conversion to sinus rhythm, maintenance of sinus rhythm, and prevention of thromboembolism. Clinical and transthoracic echocardiographic features are important in determining etiology and directing therapy for atrial fibrillation. Left atrial size, left ventricular wall thickness, and left ventricular function have independent predictive value for determining the risk of developing atrial fibrillation. Left atrial size may have predictive value in determining the success of cardioversion and maintaining sinus rhythm in selected clinical settings but has less value in the most frequently encountered group, patients with nonvalvular atrial fibrillation, in whom the duration of atrial fibrillation is the most important feature. When selecting pharmacological agents to control ventricular rate, convert to sinus rhythm, and maintain normal sinus rhythm, transthoracic echocardiography (TTE) allows noninvasive evaluation of left ventricular function and hence guides management. The combination of clinical and transthoracic echocardiographic features also allows risk stratification for thromboembolism and hemorrhagic complications in atrial fibrillation. High-risk clinical features for thromboembolism supported by epidemiological observations, results of randomized clinical trials, and meta-analyses include rheumatic valvular heart disease, prior thromboembolism, congestive heart failure, hypertension, older (> 75 years old) women, and diabetes. Small series of cases also suggest those with hyperthyroidism and hypertrophic cardiomyopathy are at high risk. TTE plays a unique role in confirming or discovering high-risk features such as rheumatic valvular disease, hypertrophic cardiomyopathy, and decreased left ventricular function. Validation of the risk stratification scheme used in the Stroke Prevention in Atrial Fibrillation-III trial is welcomed by clinicians who are faced daily with balancing the benefit and risks of anticoagulation to prevent thromboembolism inpatients with atrial fibrillation. [source] Regional distribution of collagen and haemosiderin in the lungs of horses with exercise-induced pulmonary haemorrhageEQUINE VETERINARY JOURNAL, Issue 6 2009F. J. Derksen Summary Reasons for performing study: Regional veno-occlusive remodelling of pulmonary veins in EIPH-affected horses, suggests that pulmonary veins may be central to pathogenesis. The current study quantified site-specific changes in vein walls, collagen and haemosiderin accumulation, and pleural vascular profiles in the lungs of horses suffering EIPH. Hypothesis: In the caudodorsal lung regions of EIPH-affected horses, there is veno-occlusive remodelling with haemosiderosis, angiogenesis and fibrosis of the interstitium, interlobular septa and pleura. Methods: Morphometric methods were used to analyse the distribution and accumulation of pulmonary collagen and haemosiderin, and to count pleural vascular profiles in the lungs of 5 EIPH-affected and 2 control horses. Results: Vein wall thickness was greatest in the dorsocaudal lung and significantly correlated with haemosiderin accumulation. Increased venous, interstitial, pleural and septal collagen; lung haemosiderin; and pleural vascular profiles occurred together and changes were most pronounced in the dorsocaudal lung. Further, haemosiderin accumulation colocalised with decreased pulmonary vein lumen size. Vein wall thickening, haemosiderin accumulation and histological score were highly correlated and these changes occurred only in the caudodorsal part of the lung. Conclusion: The colocalisation of these changes suggests that regional (caudodorsal) venous remodelling plays an important role in the pathogenesis of EIPH. Potential relevance: The results support the hypothesis that repeated bouts of venous hypertension during strenuous exercise cause regional vein wall remodelling and collagen accumulation, venous occlusion and pulmonary capillary hypertension. Subjected to these high pressures, there is capillary stress failure, bleeding, haemosiderin accumulation and, subsequently, lung fibrosis. [source] Fatty acid metabolism assessed by 125I-iodophenyl 9-methylpentadecanoic acid (9MPA) and expression of fatty acid utilization enzymes in volume-overloaded heartsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2004T. Miyamoto Abstract Background, The peroxisome proliferator-activated receptor (PPAR) , is a member of the nuclear receptor superfamily and regulates gene expression of fatty acid utilization enzymes. In cardiac hypertrophy and heart failure by pressure-overload, myocardial energy utilization reverts to the fetal pattern, and metabolic substrate switches from fatty acid to glucose. However, myocardial metabolism in volume-overloaded hearts has not been rigorously studied. The aim of the present study was to examine fatty acid metabolism and protein expressions of PPAR, and fatty acid oxidation enzymes in volume-overloaded rabbit hearts. Methods, Volume-overload was induced by carotid-jugular shunt formation. Sham-operated rabbits were used as control. Chronic volume-overload increased left ventricular weight and ventricular cavity size, and relative wall thickness was decreased, indicating eccentric cardiac hypertrophy. 125I-iodophenyl 9-methylpentadecanoic acid (9MPA) was intravenously administered, and animals were sacrificed at 5 min after injection. The 9MPA was rapidly metabolized to iodophenyl-3-methylnonanoic acid (3MNA) by ,-oxidation. Lipid extraction from the myocardium was performed by the Folch method, and radioactivity distribution of metabolites was assayed by thin-layer chromatography. The protein was extracted from the left ventricular myocardium, and levels of PPAR, and fatty acid oxidation enzymes were examined by Western blotting. Results, Myocardial distribution of 9MPA tended to be more heterogeneous in shunt than in sham rabbits (P = 0·06). In volume-overloaded hearts by shunt, the conversion from 9MPA to 3MNA by ,-oxidation was faster than the sham-control hearts (P < 0·05). However, protein levels of PPAR, and fatty acid utilization enzymes were unchanged in shunt rabbits compared with sham rabbits. Conclusions, These data suggest that myocardial fatty acid metabolism is enhanced in eccentric cardiac hypertrophy by volume-overload without changes in protein expressions of PPAR, and fatty acid utilization enzymes. Our data may provide a novel insight into the subcellular mechanisms for the pathological process of cardiac remodelling in response to mechanical stimuli. [source] Correlation of ,-skeletal actin expression, ventricular fibrosis and heart function with the degree of pressure overload cardiac hypertrophy in ratsEXPERIMENTAL PHYSIOLOGY, Issue 3 2006Donatella Stilli We have analysed alterations of ,-skeletal actin expression and volume fraction of fibrosis in the ventricular myocardium and their functional counterpart in terms of arrhythmogenesis and haemodynamic variables, in rats with different degrees of compensated cardiac hypertrophy induced by infra-renal abdominal aortic coarctation. The following coarctation calibres were used: 1.3 (AC1.3 group), 0.7 (AC0.7) and 0.4 mm (AC0.4); age-matched rats were used as controls (C group). One month after surgery, spontaneous and sympathetic-induced ventricular arrhythmias were telemetrically recorded from conscious freely moving animals, and invasive haemodynamic measurements were performed in anaesthetized animals. After killing, subgroups of AC and C rats were used to evaluate in the left ventricle the expression and spatial distribution of ,-skeletal actin and the amount of perivascular and interstitial fibrosis. As compared with C, all AC groups exhibited higher values of systolic pressure, ventricular weight and ventricular wall thickness. AC0.7 and AC0.4 rats also showed a larger amount of fibrosis and upregulation of ,-skeletal actin expression associated with a higher vulnerability to ventricular arrhythmias (AC0.7 and AC0.4) and enhanced myocardial contractility (AC0.4). Our results illustrate the progressive changes in the extracellular matrix features accompanying early ventricular remodelling in response to different degrees of pressure overload that may be involved in the development of cardiac electrical instability. We also demonstrate for the first time a linear correlation between an increase in ,-skeletal actin expression and the degree of compensated cardiac hypertrophy, possibly acting as an early compensatory mechanism to maintain normal mechanical performance. [source] Formation of Nickel Oxide Nanotubes with Uniform Wall Thickness by Low-Temperature Thermal Oxidation Through Understanding the Limiting Effect of Vacancy Diffusion and the Kirkendall PhenomenonADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Yi Ren Abstract In this work, the step-wise oxidation mechanism of nickel (Ni) nanowires is elucidated. Rapid vacancy diffusion plays a significant role at low temperatures in forming heterostructures of nickel oxide (NiO) nanotubes with Ni nanowires. Subsequent investigations of Ni nanowire oxidation at higher temperatures and faster temperature ramp rates show that it is difficult to bypass this rapid vacancy diffusion stage, which affects the formation of the final structure. Therefore, it is unlikely to form solid NiO nanowires or NiO nanotubes with uniform wall thickness through the conventional annealing/oxidation process of Ni nanowires. Instead, a step-wise oxidation process by combining low temperature oxidation with a chemical etching step is utilized to produce for the first time NiO nanotubes with uniform wall thickness from Ni nanowires. [source] An overview of the damage approach of durability modelling at elevated temperatureFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2001J.-L. Chaboche Lifetime prediction techniques for components working at elevated temperature are revisited. Two damage approaches in which time effects at high temperature are introduced in different ways are discussed in greater detail. First, a creep,fatigue damage model considers the interaction of the two processes during the whole life before macrocrack initiation; and second, a creep,fatigue,oxidation model separates the fatigue life into two periods: during initiation the environment-assisted processes interact with fatigue, although bulk creep damage only interacts during the micropropagation period. The second model is illustrated by its application to a coated single-crystal superalloy used in aerojet turbine blades. Its capabilities are illustrated in a number of isothermal and thermomechanical fatigue tests. Anisotropy effects are also briefly discussed and a special test, introducing cyclic thermal gradients through the wall thickness of a tubular component, demonstrates the predictive capabilities for actual engine conditions. [source] Effect of suramin on the human pathogen Candida albicans: implications on the fungal development and virulenceFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2007Lys Adriana Braga-Silva Abstract Candida albicans is an opportunistic pathogen that is of growing medical importance because it causes superficial, mucosal and systemic infections in susceptible individuals. Here, the effect of suramin, a polysulfonated naphthylurea derivative, on C. albicans development and virulence was evaluated. Firstly, it was demonstrated that suramin (500 ,M) arrested its growth, showing a fungicidal action dependent on cell number. Suramin treatment caused profound changes in the yeast ultrastructure as shown by transmission electron microscopy. The more important changes were the enlargement of the fungi cytoplasmic vacuoles, the appearance of yeasts with an empty cytoplasm resembling ghost cells and a reduction in cell wall thickness. Suramin also blocked the transformation of yeast cells to the germ-tube and the interaction between C. albicans and epithelial cells. In order to ascertain that the action of suramin on C. albicans growth is a general feature instead of being strain-specific, the effects of suramin on 14 oral clinical strains isolated from healthy children and HIV-positive infants were analyzed. Interestingly, the strains of C. albicans isolated from HIV-positive patients were more resistant to suramin than strains isolated from healthy patients. Altogether, the results produced here show that suramin interfered with essential fungal processes, such as growth, differentiation and interaction with host cells. [source] One- and Two-Dimensionally Structured Polymer Networks in Liquid Crystals for Switchable Diffractive Optical Applications,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2004P. Kossyrev Abstract We have created one- and two-dimensionally structured polymer networks dispersed in a liquid-crystal solvent using a holographic exposure technique. These structures have potential for electrically switchable, reverse-mode, polarization selective and non-selective diffractive optical elements. Using a simple phenomenological model to describe our diffraction measurements in conjunction with microscopic studies, we are able to estimate the structured polymer wall thickness as a function of monomer concentration. [source] Uremic hyperhomocysteinemia: A randomized trial of folate treatment for the prevention of cardiovascular eventsHEMODIALYSIS INTERNATIONAL, Issue 2 2007Areuza C. A. VIANNA Abstract Homocysteine is a risk factor for atherosclerosis in the general population, and serum homocysteine levels are almost universally elevated in chronic renal failure patients. When such patients are treated with dialysis, cardiovascular disease accounts for more than 50% of their mortality, which, in some proportion, may be pathophysiologically related to the elevated serum homocysteine levels. From April 2003 to March 2005, we conducted a 2-year, double-blind, randomized, placebo-controlled trial of 186 patients with end-stage kidney disease due to any cause, who were older than 18 years and stable on hemodialysis. Patients were assigned to receive either oral folic acid 10 mg 3 times a week immediately after every dialysis session under nurse supervision or an identical-appearing placebo for the entire study. On admission, plasma total homocysteine (tHcy) levels were above 13.9 ,mol/L in 96.7% of patients (median 25.0 ,mol/L, range 9.3,104.0 ,mol/L). In the placebo group, tHcy levels remained elevated at 6, 12, and 24 months, while oral folate significantly decreased tHcy to a median value of 10.5 (2.8,20.3) ,mol/L, (p<0.01). During the study, 38 patients (folic acid group 17 vs. placebo group 21; p=0.47) died from cardiovascular disease. Kaplan,Meier life table analysis dealing with the incidence of cardiovascular events, both fatal and nonfatal (myocardial infarction, arrhythmias, angina, heart failure, cerebrovascular accident), showed that 2 years of folic acid treatment and the lowering of the homocysteine blood levels had no effect on cardiovascular events (p=0.41; hazard ratio 1.24, 95% CI 0.74,2.10). However, the carotid artery intima-media wall thickness measured in a blinded fashion decreased from 1.94 ± 0.59 mm to 1.67 ± 0.38 mm (p<0.01) after 2 years of folate therapy. In this short-term study of uremic patients, 2 years of folic acid supplementation normalized the tHcy blood levels in 92.3% of patients but did not change the incidence of cardiovascular events compared with the control group. However, ultrasonography of the common carotid arteries performed at entry and 24 months later showed a significant decrease in intima-media thickness with folate supplementation. This suggests that early folate supplementation may benefit patients with chronic renal failure by preventing cardiovascular deterioration. [source] | ||||||||||||||||||||||||||||||||||||||||