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Stress Testing (stress + testing)

Distribution by Scientific Domains
Medical Sciences78%
5 Other Domains22%

Kinds of Stress Testing

  • exercise stress testing
    		•
  • treadmill stress testing
    		•

    Selected Abstracts

    Stress Testing of Financial Industries: A Simple New Approach to Joint Stress Testing of Korean Banking, Securities, and Non-Life Insurance Industries,

    ASIA-PACIFIC JOURNAL OF FINANCIAL STUDIES, Issue 4 2009
    Kook-Hyun Chang
    Abstract This paper proposes a simple joint stress testing model useful in studying the effects of specific stress scenarios on a financial sector. In doing so, we adopt the principal component analysis (PCA) as a main device to interpret various financial information contained in figures and numbers on a financial company. We repeat the principal component analysis across different levels from individual company to a financial industry, and eventually to a financial sector as a whole to derive a financial sector risk index. We then link the sector risk index with stress macro variables, which constitute a much simpler task than devising individual models for each financial components. Once a relationship is established, a joint stress test is conducted by repeating PCA conversely. As a sample of stress scenario in the paper, we use the case of the 2003 credit card distress. We find that securities industry is more sensitive to market stresses than two other industries-bank and insurance-and that financial institutions in such a stress-sensitive industry are, consequently, more affected by the stresses than those in other industries. Despite the simplicity of the proposed model, this model is expected to provide substantial information, particularly for financial supervisors without having to build a complicated joint stress testing model. [source]

    Osteitis condensans ilii: a significant association with sacroiliac joint tenderness in women

    INTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 1 2009
    Katey JENKS
    Abstract Aim:, To determine whether subjects with radiological evidence of osteitis condensans ilii exhibit symptoms and signs in common with sacroiliitis when compared with an age-matched control group and to examine demographic features. Methods:, The Dunedin Hospital radiology database was searched for all subjects with changes of osteitis condensans ilii over a 10-year period. An age-matched control group with plain X-rays of the pelvis was recruited from the same database. All subjects were sent a questionnaire enquiring about back pain and details of previous pregnancies. Those who responded to the questionnaire were invited for clinical assessment. Results:, Thirty-five individuals with osteitis condensans ilii were identified over the 10-year period. All were female and reported prior pregnancy supporting an association between osteitis condensans ilii and pregnancy. Stress testing of the sacroiliac joints was associated with greater tenderness in the osteitis condensans ilii group with a mean of 1.8 positive tests out of a possible 4, compared to 0.8 in the control group (Wilcoxon rank-sum test P = 0.02). Comparison between the two groups showed no difference in number of pregnancies, newborn weight, presence of back pain, back pain assessed by the Oswestry Low Back Pain Questionnaire or loss of function using the Bath Ankylosing Spondylitis Functional Index (BASFI). Conclusion:, Osteitis condensans ilii is associated with tenderness during sacroiliac joint compression tests and should be considered in the differential diagnosis when sacroiliac joint tenderness is elicited. [source]

    Sildenafil-mediated neovascularization and protection against myocardial ischaemia reperfusion injury in rats: role of VEGF/angiopoietin-1

    JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 6b 2008
    Srikanth Koneru
    Abstract Sildenafil citrate (SC), a drug for erectile dysfunction, is now emerging as a cardiopulmonary drug. Our study aimed to determine a novel role of sildenafil on cardioprotection through stimulating angiogenesis during ischaemia (I) reperfusion (R) at both capillary and arteriolar levels and to examine the role of vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1) in this mechanistic effect. Rats were divided into: control sham (CS), sildenafil sham (SS), control + IR (CIR) and sildenafil + IR (SIR). Rats were given 0.7 mg/kg, (i.v) of SC or saline 30 min. before occlusion of left anterior descending artery followed by reperfusion (R). Sildenafil treatment increased capillary and arteriolar density followed by increased blood flow (2-fold) compared to control. Treatment with sildenafil demonstrated increased VEGF and Ang-1 mRNA after early reperfusion. PCR data were validated by Western blot analysis. Significant reduction in infarct size, cardiomyocyte and endothelial apoptosis were observed in SC-treated rats. Increased phosphorylation of Akt, eNOS and expression of anti-apoptotic protein Bcl-2, and thioredoxin, hemeoxygenase-1 were observed in SC-treated rats. Echocardiography demonstrated increased fractional shortening and ejection fraction following 45 days of reperfusion in the treatment group. Stress testing with dobutamine infusion and echocardiogram revealed increased contractile reserve in the treatment group. Our study demonstrated for the first time a strong additional therapeutic potential of sildenafil by up-regulating VEGF and Ang-1 system, probably by stimulating a cascade of events leading to neovascularization and conferring myocardial protection in in vivo I/R rat model. [source]

    Dynamic Analysis of Exercise Oxygen Consumption Predicts Outcomes in Advanced Heart Failure

    CONGESTIVE HEART FAILURE, Issue 6 2007
    Guy A. MacGowan MD
    It is unclear whether cardiopulmonary stress testing provides prognostic information in patients with very advanced heart failure receiving contemporary medical therapy. Analysis of cardiopulmonary treadmill stress data in a group of patients with advanced heart failure and severe functional impairment was performed (N=102, peak exercise oxygen consumption [VO2] ,14 mL/kg/min, 47% receiving ,-blockers). Dynamic variables (peak - baseline values) better predicted outcomes than did single value peak measurements, especially ,VO2. Multivariate analysis showed that usage of ,-blockers and ,VO2 (both P<.05) independently and significantly predicted outcomes. Subgroup analysis showed that ,VO2 was particularly useful in predicting outcomes in patients with ischemic cardiomyopathy or who were not receiving ,-blockers. Thus, in patients with very advanced heart failure, cardiopulmonary stress testing-derived ,VO2 provides important prognostic information useful to help predict clinical deterioration or death, particularly for patients with ischemic cardiomyopathy or who are not receiving ,-blockers. [source]

    Ten-Year Echo/Doppler Determination of the Benefits of Aerobic Exercise after the Age of 65 Years

    ECHOCARDIOGRAPHY, Issue 1 2010
    Alexander J. Muster M.D.
    As the human lifespan becomes progressively extended, potential health-related effects of intense aerobic exercise after age 65 need evaluation. This study evaluates the cardiovascular (CV), pulmonary, and metabolic effects of competitive distance running on age-related deterioration in men between 69 (±3) and 77 (±2) years (mean ± SD). Twelve elderly competitive distance runners (ER) underwent oxygen consumption and echo/Doppler treadmill stress testing (Balke protocol) for up to 10 years. Twelve age-matched sedentary controls (SC) with no history of CV disease were similarly tested and the results compared for the initial three series of the study. CV data clearly separated the ER from SC. At entry, resting and maximal heart rate, systolic/diastolic blood pressure, peak oxygen consumption (VO2max), and E/A ratio of mitral inflow were better in the ER (P < 0.05 vs. SC). With aging, ER had a less deterioration of multiple health parameters. Exceptions were VO2max and left ventricular diastolic function (E/A, AFF, IVRT) that decreased (P < 0.05, Year 10 vs. Year 1). Health advantages of high-level aerobic exercise were demonstrated in the ER when compared to SC. Importantly, data collected in ER over 10 years confirm the benefit of intensive exercise for slowing several negative effects of aging. However, the normative drop of exercise capacity in the seventh and eighth decades reduces the potential athleticism plays in prevention of CV events. (Echocardiography 2010;27:5-10) [source]

    Role of Parasternal Data Acquisition During Contrast Enhanced Real-Time Three-Dimensional Echocardiography

    ECHOCARDIOGRAPHY, Issue 10 2007
    Attila Nemes M.D., Ph.D.
    Background: Recent technical developments have resulted in high-resolution real time three-dimensional echocardiography (RT3DE). The purpose of this study was to investigate the beneficial role of parasternal-acquired images in addition to apical-acquired images during contrast stress RT3DE. Methods: The study comprised 30 consecutive patients (52 ± 11 years, 18 males) with chest pain referred for routine stress testing. The contrast RT3DE images were acquired from the apical and parasternal window with a Sonos 7500 echo system attached to a X4 matrix array transducer. Results: From the apical and parasternal acquisition, 464 segments (91%) and 267 segments (52%) could be analyzed, respectively (P < 0.001). From the apical window, more basal segments were not analyzable (22 of 180, 12% vs. 24 of 330, 7%; P = 0.06). From the parasternal window, more apical segments were not analyzable (117 of 150, 78% vs. 126 of 360, 35%; P < 0.01). The mean image quality index of the 464 analyzable segments from the apical-acquired images was 2.43. Fourteen of 180 basal segments (8%), 12 of 180 midventricular segments (7%) and 2 of 150 apical segment (1%) were only available with parasternal data acquisition. In addition to these 28 segments, 79 segments (15%) already visualized from the apical window improved in quality. The overall mean image quality index, now assessed from 492 (96%) of all segments, using both the apical and parasternal acquired data, improved to 2.74 (P < 0.05). Conclusions: Addition of parasternal to apical acquisition of contrast RT3DE data can decrease the number of nonvisualized segments and improve mean image quality. [source]

    Doppler Ultrasound in Mice

    ECHOCARDIOGRAPHY, Issue 1 2007
    Jörg Stypmann
    Color, power, spectral, and tissue Doppler have been applied to mice. Due to the noninvasive nature of the technique, serial intraindividual Doppler measurements of cardiovascular function are feasible in wild-type and genetically altered mice before and after microsurgical procedures or to follow age-related changes. Fifty-megahertz ultrasound biomicroscopy allows to record the first beats of the embryonic mouse heart at somite stage 5, and the first Doppler-flow signals can be recorded after the onset of intrauterine cardiovascular function at somite stage 7. Using 10- to 20-MHz ultrasound transducers in the mouse embryo, cardiac, and circulatory function can be studied as early as 7.5 days after postcoital mucous plug. Postnatal Doppler ultrasound examinations in mice are possible from birth to senescent age. Several strain-, age-, and gender-related differences of Doppler ultrasound findings have been reported in mice. Results of Doppler examinations are influenced by the experimental settings as stress testing or different forms of anesthesia. This review summarizes the present status of Doppler ultrasound examinations in mice and animal handling in the framework of a comprehensive phenotype characterization of cardiac contractile and circulatory function. [source]

    Diagnosing cardiac disease in equine athletes: the role of stress testing

    EQUINE VETERINARY JOURNAL, Issue 2 2005
    M. DURANDO
    No abstract is available for this article. [source]

    Impact of genetic defects on coronary atherosclerosis in patients suspected of having familial hypercholesterolaemia

    EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2003
    O. S. Descamps
    Abstract Background In the present study we assessed whether the presence of genetic mutations typical of familial hypercholesterolaemia (FH) was associated with greater atherosclerosis in the coronary vessels in patients with severe hypercholesterolaemia and a family history of early cardiovascular disease. Materials and methods Two hundred and thirty-five patients selected for having severe hypercholesterolaemia and a family history of cardiovascular disease were classified as FH (57 men and 38 women) or non-FH (84 men and 56 women) according to a genetic analysis of the LDL-R or ApoB genes. Coronary atherosclerosis was evaluated by performing a thoracic CT scan and exercise stress testing. Results Familial hypercholesterolaemia individuals had a significantly higher prevalence of coronary calcification than the non-FH patients from among both the men (OR = 3·90; 95% CI 1·86,8·19; P < 0·001) and the women (OR = 2·34; 95% CI 1·01,5·48; P = 0·05). In exercise stress testing, ECG abnormalities suggestive of cardiac ischaemia were found with a higher prevalence in the FH patients than the non-FH patients from among both the men (OR 6·15; 95% CI 2·16,17·5; P < 0·001) and the women (OR 4·76; 95% CI 0·91,24·6; P = 0·06). All differences were statistically significant after adjusting for age and cholesterol and for most classical risk factors that differed between the FH and non-FH groups. Conclusion Among patients with severe hypercholesterolaemia and a family history of early cardiovascular disease, the presence of a genetically ascertained FH is associated with a higher prevalence of coronary artery calcifications and a positive exercise stress test. These results suggest that despite a similar phenotype, patients carrying mutations suggestive of FH may have a greater cardiovascular risk than patients without these mutations. [source]

    Sonography of the normal scapholunate ligament and scapholunate joint space

    JOURNAL OF CLINICAL ULTRASOUND, Issue 4 2001
    James Francis Griffith FRCR
    Abstract Purpose The aims of this study were to assess the visibility of the normal scapholunate ligament on sonography and to establish the normal scapholunate joint space width in the neutral position and radial and ulnar deviation. Methods Two hundred normal wrists in 100 subjects (55 men and 45 women; mean age, 40 years; range, 19,83 years) were examined with high-resolution sonography (5,12-MHz linear-array transducer). The visibility and thickness of the scapholunate ligament were recorded. The width of the scapholunate joint space, or interval, was measured in the neutral position and radial and ulnar deviation. The width of the distal radius was recorded as a comparative standard for the patients' body habitus. Results The dorsal scapholunate ligament was completely (100%) visible in 95 wrists (48%), partially (, 50%) visible in 60 (30%), barely (< 50%) visible in 15 (8%), and not visible in 30 (15%). The volar scapholunate ligament was completely visible in 13 wrists (7%), partially visible in 17 (9%), barely visible in 15 (8%), and not visible in 151 (76%). The proximal component of the ligament was not visible in any subject. Measurement of the scapholunate interval was limited by the lack of identifiable anatomic marks for reference. The mean width of the dorsal scapholunate interval was 4.2 mm (range, 2.3,6.3 mm) in the neutral position. The interval did not differ more than 2.5 mm between the left and right wrists. No predictable change in width on ulnar or radial deviation was evident. The mean scapholunate intervals and mean distal radial width were significantly wider in men than in women and on the right side than on the left side. Conclusions The dorsal scapholunate ligament is completely or partially visible in 78% of normal wrists. Its detection following injury may help to exclude the possibility of scapholunate dissociation. There is a quite wide variation in scapholunate interval widths on sonography and an unpredictable response with stress testing. The absence of a visible scapholunate ligament on sonography does not indicate injury. © 2001 John Wiley & Sons, Inc. J Clin Ultrasound 29:223,229, 2001. [source]

    Aortic Stenosis: Assessment of the Patient at Risk

    JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 6 2007
    KHUNG KEONG YEO M.B.B.S.
    The true incidence of aortic stenosis among the general population is unknown but aortic sclerosis, its precursor, has been estimated to affect about 25% of people over age 65, while an estimated 3% of the population over age 75 have severe aortic stenosis. Severe aortic stenosis, when accompanied by symptoms of angina, syncope, or heart failure, is associated with high mortality rates. Two-dimensional and Doppler echocardiography are cornerstone tools for the evaluation and monitoring of aortic stenosis. Echocardiography helps identify the patient at risk of death and guide timing of aortic valve replacement. Other important diagnostic tools include cardiac catheterization, treadmill stress testing, and dobutamine stress echocardiography, although their use is limited to specific patient populations. Aortic valve replacement carries a significant operative risk of approximately 4.0%. However, risk of operative mortality varies according to comorbidities and disease presentation. There are many risk models that guide estimation of the risk of operative mortality. Understanding operative risk is important in patient care and the selection of patients for aortic valve replacement. [source]

    Exercise-Induced Nonsustained Ventricular Tachycardia: A Significant Marker of Coronary Artery Disease?

    JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 3 2002
    MARTIN FEJKA M.D.
    Diagnostic exercise stress testing is commonly performed in patients with known or suspected cardiovascular disease. The significance of an ischemic response, manifested as significant ST-segment depression, angina pectoris, transient myocardial perfusion abnormalities, or combinations thereof, is well established. However, the diagnostic implications of exercise-induced nonsustained VT are uncertain, especially as an isolated finding. The patient had threatening ventricular arrhythmias at peak exercise without an ischemic response. Subsequent cardiac catheterization revealed significant CAD requiring percutaneous coronary intervention. [source]

    The Effects of Rate-Adaptive Atrial Pacing Versus Ventricular Backup Pacing on Exercise Capacity in Patients with Left Ventricular Dysfunction

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2009
    M.S.C.E., ROD PASSMAN M.D.
    Background: Atrial rate-adaptive pacing may improve cardiopulmonary reserve in patients with left ventricular dysfunction. Methods: A randomized, blinded, single-crossover design enrolled dual-chamber implantable defibrillator recipients without pacing indications and an ejection fraction ,40% to undergo cardiopulmonary exercise treadmill stress testing in both atrial rate-adaptive pacing (AAIR) and ventricular demand pacing (VVI) pacing modes. The primary endpoint was change in peak oxygen consumption (VO2). Secondary endpoints were changes in anaerobic threshold, perceived exertion, exercise duration, and peak blood pressure. Results: Ten patients, nine males, eight with New York Heart Association class I, mean ejection fraction 24 ± 7%, were analyzed. Baseline VO2 was 3.6 ± 0.5 mL/kg/min. Heart rate at peak exercise was significantly higher during AAIR versus VVI pacing (142 ± 18 vs 130 ± 23 bpm; P = 0.05). However, there was no difference in peak VO2 (AAIR 23.7 ± 6.1 vs VVI 23.8 ± 6.3 mL/kg/min; P = 0.8), anaerobic threshold (AAIR 1.3 ± 0.3 vs VVI 1.2 ± 0.2 L/min; P = 0.11), rate of perceived exertion (AAIR 7.3 ± 1.5 vs VVI 7.8 ± 1.2; P = 0.46), exercise duration (AAIR 15 minutes, 46 seconds ± 2 minutes, 54 seconds vs VVI 16 minutes, 3 seconds ± 2 minutes, 48 seconds; P = 0.38), or peak systolic blood pressure (AAIR 155 ± 22 vs VVI 153 ± 21; P = 0.61) between the two pacing modes. Conclusion: In this study, AAIR pacing did not improve peak VO2, anaerobic threshold, rate of perceived exertion, or exercise duration compared to VVI backup pacing in patients with left ventricular dysfunction and no pacing indications. [source]

    Biventricular Pacing as Alternative Therapy for Dilated Cardiomyopathy Associated with Congenital Heart Disease

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2001
    EDWIN RODRÍGUEZ-CRUZ
    RODRÍGUEZ-CRUZ, E., et al.: Biventricular Pacing as Alternative Therapy for Dilated Cardiomyopathy Associated with Congenital Heart Disease. Biventricular, alternative, and multisite pacing are currently being explored to improve cardiac function among patients with medically refractory, end-stage dilated cardiomyopathies. Although, due to inherent myocardial abnormalities, patients with repaired congenital heart defects may be at a greater risk than others to develop heart failure, often requiring cardiac transplantation. The efficacy of biventricular pacing among these patients is unknown. This report presents a patient with successfully repaired congenital heart disease in infancy who developed a symptomatic dilated cardiomyopathy at 22 years of age. Following biventricular pacing, systemic ventricular function showed a 14% improvement in ventricular dP/dt. One month later, subjective symptoms improved and cardiac ultrasound illustrated a 125% increase in fractional area of change. Exercise stress testing showed a 17% improvement in aerobic work capacity. [source]

    Adenosine Induced Monomorphic Ventricular Tachycardia

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2000
    DEEPIKA MISRA
    Polymorphic ventricular tachycardia has been reported following the administration of adenosine for the treatment of SVT. We present a case of monomorphic ventricular tachycardia in a 75-year-old man following the intravenous administration of adenosine for stress testing. [source]

    Cardiopulmonary responses of asthmatic children to exercise: Analysis of systolic and diastolic cardiac function

    PEDIATRIC PULMONOLOGY, Issue 3 2007
    Bulent Alioglu MD
    Abstract The aim of this study was to evaluate aerobic exercise capacity, cardiac features and function in a group of asthmatic children who underwent medical treatment. Dynamic exercise testing was done to evaluate aerobic exercise capacity. Echocardiography was performed to identify the effects that asthma-induced pulmonary changes have on respiratory and cardiac function in these patients. The study involved 20 asthmatic children (aged 7,16 years) who were followed at our hospital and 20 age- and sex-matched, healthy control subjects. Sixteen of the asthma cases were moderate and four were severe. All 40 subjects underwent similar series of assessments: multiple modes of echocardiography, treadmill stress testing, pulmonary function testing. The means for forced expiratory volume in 1 sec, forced expiratory flow 25,75%, maximal voluntary ventilation and inspiratory capacity were all significantly higher in the control group. The patient group had significantly lower mean maximal oxygen uptake and mean endurance time than the controls but there were no significant differences between the groups with respect to respiratory exchange ratio or the ventilatory threshold. The control group means for ejection fraction, fractional shortening, left ventricular mass, and left ventricular mass index were significantly higher than the corresponding patient group results. Children with moderate or severe asthma have lower aerobic capacity than healthy children of the same age. The data suggest that most of these children have normal diastolic cardiac function, but exhibit impaired systolic function and have lower LVM than healthy peers of the same age. Pediatr Pulmonol. 2007; 42:283,289. © 2007 Wiley-Liss, Inc. [source]

    GaN HEMT thermal behavior and implications for reliability testing and analysis

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
    Daniel S. Green
    Abstract GaN HEMT reliability evaluation in a typical Arrhenius manner requires establishing peak junction temperature for a particular stress condition. Several new techniques have yielded promising results toward establishing peak temperature for these devices in combination with detailed physical modeling, particularly micro-Raman imaging. This paper compares results from finite element modeling to measurements by infrared imaging and micro-Raman imaging. The limitations of IR imaging were confirmed similar to earlier reports. Two techniques for establishing temperature from micro-Raman measurements were used to reveal excellent correlation to the model, and also provide insight into the relationship between temperature and structural change in the device. Temperature modeling data is reported for base plate temperature from 85°C to 250°C for practical GaN HEMT devices. Implications of the measurements for GaN HEMT reliability stress testing and analysis will be discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Chest pain is inversely associated with blood pressure during exercise among individuals being assessed for coronary heart disease

    PSYCHOPHYSIOLOGY, Issue 2 2007
    Blaine Ditto
    Abstract Acute and chronic increases in blood pressure have been related to decreases in pain perception. This phenomenon has been studied primarily using acute experimental pain stimuli. To extend the literature to naturalistic pain and in particular the problem of silent cardiac ischemia, this study examined the relationship between blood pressure and chest pain during exercise stress testing. Nine hundred seven (425 men, 482 women) individuals undergoing exercise stress testing for diagnosis of possible myocardial ischemia completed the McGill Pain Questionnaire (MPQ) immediately afterward and other questionnaires before and after testing. Blood pressure was measured before, during, and after exercise. Systolic blood pressure at the end of exercise was inversely related to a number of measures of pain such as total score on the MPQ. The relationship could not be explained by individual differences in exercise duration, medication use, sex, or other measured variable. In sum, the inverse relationship between blood pressure and sensitivity to pain that has been observed in other populations in experimental and naturalistic conditions was observed for chest pain during exercise. Blood pressure may contribute to episodes of silent ischemia. [source]

    Total System Reliability: Integrated Model for Growth and Test Termination

    QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 4 2005
    John Donovan
    Abstract Reliability demonstration testing is not the most efficient method of assuring product reliability prior to shipment. It is costly, time consuming and has inherent technical and social limitations. The dilemma facing the reliability and quality engineer is whether to continue demonstration testing and risk shipping a product late or ship the product and risk warranty and field service returns. Either option can cause the company to lose significant market share and profit. This paper sets out to solve this dilemma by meeting both the time to market constraints and the product reliability goals. The weaknesses of existing reliability demonstration techniques are explored and a comprehensive methodology is introduced involving controlled development processes, stress testing, root cause determination and process change feedback mechanisms. All prototype products are manufactured on the final volume process line resulting in the early identification and correction of process-related problems. Testing commences on the first available prototypes with system stress/robust testing being employed to stimulate failures, determine their root cause and correct them. Reliability growth modelling assesses the ongoing improvements occurring in reliability during the development cycle, while a statistical stopping rule is used to determine the optimal product release time without risking product warranty. The approach is applicable to systems incorporating both hardware and software elements. The methodology has been validated on three development projects of telecommunication systems comprising hardware and software. In addition to enhancing team behaviour and performance, the development times have been reduced by 14% and the ramp-up time to full worldwide product shipments has been reduced by 50%. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Hormone Replacement Therapy Shortens QT Dispersion in Healthy Postmenopausal Women

    ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2001
    Aylin Yildirir M.D.
    Background: The aim of the study was to investigate the effects of hormone replacement therapy (HRT) on myocardial repolarization characteristics in postmenopausal women without coronary artery disease. Methods: Fifty-one consecutive healthy postmenopausal women (age 48 ±; 5) with negative exercise stress testing were prospectively enrolled into the study. Standard 12-lead electrocardiograms were obtained to evaluate the effects of 6 months of HRT on QT intervals, corrected QT intervals (QTcmax and QTcmin), QT dispersion (QTd), and corrected QTd (QTcd). Hormone regimens were continuous 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone depending on the hysterectomy status. Results: Although not statistically significant, CEE alone or in combination with MPA increased QTmax and QTmin values. However, the increase in QTmin was greater than the increase in QTmax, which resulted in statistically significant shortening of QTd (P = 0.007 in CEE and P < 0.001 in CEE + MPA groups). There was a significant prolongation of QTcmin values after 6 months in patients assigned to the CEE group (P = 0.001). The QTcd values were significantly shortened by HRT with both regimens (for CEE group 49 ±; 13 ms vs 38 ±; 13 ms, P = 0.01; for CEE + MPA group 49 ±; 14 ms vs 36 ±; 13, P < 0.001). Conclusion: HRT significantly decreased the QTd and QTcd in postmenopausal women without coronary artery disease, independent of the addition of MPA to the regimen. This improvement in myocardial repolarization may be one of the mechanisms of the favorable effects of HRT on cardiovascular system. However, the clinical implications of the shortening of QTd in postmenopausal women with HRT must be clarified. A.N.E. 2001; 6(3):193,197 [source]

    Piecewise analysis and modeling of circuit pack temperature cycling data

    BELL LABS TECHNICAL JOURNAL, Issue 3 2006
    Toby Joyce
    Temperature cycling environmental stress testing (EST) of circuit packs is a standard test procedure for the precipitation of latent defects in order to minimize early product lifecycle customer returns. EST is an expensive, energy-intensive bottleneck in the manufacturing process, one that is based on empiricisms that may be out of date. This presents great opportunity for optimization and test cost reduction. This paper describes the characterization of temperature cycling through analysis and modeling of process data in order to optimize the test parameters,ramp rate, temperature extremes, dwell times, and number of cycles. Failure data from circuit packs tested at a Lucent facility is analyzed using a regression technique and graphical inspection. The dwell and ramp periods of the test are considered in a piecewise manner. A cost model is applied based on distributions fitted to the failure data. The analysis yields a methodology for the dynamic, value-based optimization of temperature cycling EST. © 2006 Lucent Technologies Inc. [source]

    Actual Financial Comparison of Four Strategies to Evaluate Patients with Potential Acute Coronary Syndromes

    ACADEMIC EMERGENCY MEDICINE, Issue 7 2008
    Anna Marie Chang MD
    Abstract Objectives:, Small studies have shown that a negative computed tomography coronary angiogram (CTA) in low-risk chest pain patients predicts a low rate of 30-day adverse events. The authors hypothesized that an immediate CTA strategy would be as effective but less costly than alternative strategies for evaluation of patients with potential acute coronary syndrome (ACS). Methods:, The authors retrospectively compared four strategies for evaluation of patients after initial physician determination that the patient required admission and testing to rule out ACS. Patients were frequency-matched by age, race, gender, thrombolysis in myocardial infarction (TIMI) score, and initial electrocardiogram (ECG). The four groups were immediate CTA in the emergency department (ED) without serial markers (n = 98); clinical decision unit/observation unit (CDU) with biomarkers and CTA (n = 102); CDU evaluation with serial cardiac biomarkers and stress testing (n = 154); and usual care, defined as admission with serial biomarkers and hospitalist-directed evaluation (n = 289). The main outcomes were actual cost of care (facility direct and indirect fixed, facility variable direct labor and supply costs), length of stay (LOS), diagnosis of coronary artery disease (CAD), and safety (30-day death or myocardial infarction [MI]). Results:, Patients in each group were of similar age (mean ± standard deviation [SD] 46 ± 9 years), race (62% African American), and gender (57% female) and had similar TIMI scores (100% between 0,2). Comparing immediate CTA versus CDU CTA versus CDU stress versus usual care, median costs were less ($1,240 vs. 2,318 vs. 4,024 vs. 2,913; p < 0.01), and LOS was shorter (8.1 hr vs. 20.9 hr vs. 26.2 hr vs. 30.2 hr; p < 0.01). Diagnosis of CAD was similar (5.1% vs. 5.9% vs. 5.8% vs. 6.6%; p = 0.95), but fewer patients had 30-day death/MI (0% vs. 0% vs. 0.7% vs. 3.1%; p = 0.04) or 30-day readmission (0% vs. 3.2% vs. 2.3% vs. 12.2%; p < 0.01). Conclusions:, Compared to the other strategies, immediate CTA was as safe, identified as many patients with CAD, had the lowest cost, had the shortest LOS, and allowed discharge for the majority of patients. Larger prospective studies should confirm safety before immediate CTA replaces other strategies to rule out possible ACS. [source]

    Reproducible microvascular dysfunction with dobutamine infusion in Takotsubo cardiomyopathy presenting with ST segment elevation

    CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 5 2006
    Stacy D. Brewington MD
    Abstract Takotsubo (ampulla) cardiomyopathy, or broken heart syndrome, is an underrecognized cardiac illness that usually presents as an acute coronary syndrome in postmenopausal females. The disorder is frequently associated with episodes of mental or physical stress, implicating an abnormal cardiac response to increased catecholamines. Although death has been reported during the index event, the long-term prognosis is good with full recovery of left ventricular function. We present a case of Takotsubo cardiomyopathy mimicking anterior ST segment elevation myocardial infarction precipitated by dobutamine stress testing. Reinfusion of dobutamine in the catheterization laboratory reproduced symptoms with angiography and intravascular ultrasound supporting the theory of abnormal microvascular circulation as the etiology of Takotsubo cardiomyopathy. Acute and delayed magnetic resonance imaging demonstrated no infarction with complete recovery of ventricular function. © 2005 Wiley-Liss, Inc. [source]

    Gender Bias in Cardiovascular Testing Persists after Adjustment for Presenting Characteristics and Cardiac Risk

    ACADEMIC EMERGENCY MEDICINE, Issue 7 2007
    Anna Marie Chang MD
    Objectives:Previous studies have found that female patients receive fewer invasive tests for cardiovascular disease than male patients. The authors assessed whether different clinical characteristics at emergency department presentation account for this gender bias. Methods:Patients with potential acute coronary syndrome (ACS) who presented to a university hospital were prospectively identified. A structured data instrument that included demographic information, chest pain description, history, physical examination, chest radiography, and electrocardiogram (ECG) data was completed. Hospital course was tracked daily. Patients received 30-day telephone follow-up. The main outcome was whether the patients received objective evaluation for coronary artery disease after adjustment for cardiac risk, including race, age, total number of risk factors, Thrombolysis in Myocardial Infarction (TIMI) score, ECG, and whether the patient sustained an acute myocardial infarction on index hospitalization. Results:There were 3,514 women (58%) and 2,547 men (42%) studied. They had similar presenting characteristics: chest pain quality (pressure/tightness: female 60% vs. male 59%, p = 0.6), location (substernal: female 82% vs. male 80%; p = 0.2), radiation (female 27% vs. male 26%; p = 0.3), and most associated symptoms. Men had more cardiac risk factors (mean 1.5 vs 1.4; p < 0.001), more abnormal ECGs (59% vs. 48%; p < 0.001), and a higher TIMI risk score (p < 0.001). With respect to the main outcome, men received more cardiac catheterizations (12.6% vs. 6.0%; odds ratio [OR], 2.25; 95% confidence interval [CI] = 1.88 to 2.70) and more stress tests (14.7% vs. 12.3%; OR, 1.22; 95% CI = 1.05 to 1.42). After adjustment for age, race, cardiac risk factors, ECG, and TIMI risk score, men still received more cardiac catheterizations (adjusted OR, 1.72; 95% CI = 1.40 to 2.11) and stress tests (adjusted OR, 1.16; 95% CI = 1.01 to 1.33). Models adjusting for acute myocardial infarction or death, high-risk initial clinical impression, or emergency department disposition found similar results for increased likelihood of cardiac catheterization in men but no difference in stress testing between men and women. Conclusions:Female patients with potential ACS receive fewer cardiac catheterizations than male patients, even when presenting complaint, history, ECG, and diagnosis are taken into account. The gender bias cannot be explained by differences in presentation or clinical course. [source]

    Myocardial Perfusion Profile in a Young Population With and Without Known Coronary Artery Disease: Comparison by Gender

    CLINICAL CARDIOLOGY, Issue 2 2010
    Nili Zafrir MD
    Background More and more young people are being referred for evaluation or screening for coronary artery disease (CAD). However, the value of myocardial perfusion imaging (MPI) in this population is unclear, especially in the absence of symptoms. Methods The study sample included 1765 consecutive patients less than 51 years old who were referred to a major medical center for stress/rest MPI study. Clinical and MPI variables were compared between patients with and without known CAD, by gender. Results There were 1346 (76%) men and 419 (24%) women of mean age 44 ± 6 years; 461 (26%) had known CAD. Stress-induced ischemia was detected in 321 patients (18.2%) and significant ischemia in 131 (7.4%); there was no difference in the rate or severity of ischemia by presence of symptoms. Among those without known CAD, the rate of stress-induced ischemia by MPI was significantly lower in women than men. On logistic regression analysis, the independent predictors of ischemia in men were high cholesterol, diabetes, angina during stress testing, ST depression, and smoking (P<.0001); and in women, the independent predictors were diabetes and high cholesterol. Conclusion Known CAD and stress-induced ischemia are significantly more prevalent in young men than in young women, irrespective of risk factors. The independent predictors of ischemia differ between men and women. Copyright © 2010 Wiley Periodicals, Inc. [source]

    Arterial concentration of 99mTc-sestamibi at rest, during peak exercise and after dipyridamole infusion

    CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2004
    Niels Peter Rønnow Sand
    Summary Tracers for myocardial perfusion imaging during stress should not only have high cardiac uptake but they should also have a fast blood clearance to prevent myocardial tracer uptake after the ischaemic stimulus. The present study characterize the early phase of the arterial 99mTc-sestamibi (MIBI) time-activity curve after venous bolus injection at rest, during peak exercise and after dipyridamole infusion. We included 11 patients undergoing angioplasty for one-vessel disease (rest study) and 20 patients evaluated for the detection of haemodynamic significant coronary stenoses by 99mTc-sestamibi single photon emission computed tomography (SPECT) using either bicycle exercise testing (10 patients) or standard dipyridamole testing (10 patients). Arterial blood samples of 1 ml were taken from the left femoral artery (rest study) or the right radial artery (exercise and dipyridamole studies) every 5 s during the first 5 min postinjection. In the exercise and the dipyridamole studies blood sampling were extended to include blood samples every 5 min 5,30 min postinjection. Peak MIBI concentration was lower and decrease in concentration slower after tracer injection during exercise than during dipyridamole stress testing. This may cause an underestimation of perfusion defects during exercise because of MIBI uptake after the ischaemic stimulus. The implications of the study not only refer to the choice of stress modality when using MIBI. This study also underlines the importance of considering early blood clearance in addition to regional myocardial tracerkinetic aspects such as myocardial extraction fraction when new tracers are introduced. [source]