bluuebunny/crossref_metadata_2025 huggingface dataset:
Plastid Signals Remodel Light Signaling Networks and Are Essential for Efficient Chloroplast Biogenesis inArabidopsis
Authors: Ruckle Michael E. , DeMarco Stephanie M. , Larkin Robert M.
Published: December 2007

Plastid signals are among the most potent regulators of genes that encode proteins active in photosynthesis. Plastid signals help coordinate the expression of the nuclear and chloroplast genomes and the expression of genes with the functional state of the chloroplast. Here, we report the isolation of new cryptochrome1 (cry1) alleles from a screen for Arabidopsis thaliana genomes uncoupled mutants, which have defects in plastid-to-nucleus signaling. We also report genetic experiments showing that a previously unidentified plastid signal converts multiple light signaling pathways that perceive distinct qualities of light from positive to negative regulators of some but not all photosynthesis-associated nuclear genes (PhANGs) and change the fluence rate response of PhANGs. At least part of this remodeling of light signaling networks involves converting HY5, a positive regulator of PhANGs, into a negative regulator of PhANGs. We also observed that mutants with defects in both plastid-to-nucleus and cry1 signaling exhibited severe chlorophyll deficiencies. These data show that the remodeling of light signaling networks by plastid signals is a mechanism that plants use to integrate signals describing the functional and developmental state of plastids with signals describing particular light environments when regulating PhANG expression and performing chloroplast biogenesis.
Consistency in employee discipline: an empirical exploration
Authors: Cole Nina
Published: December 2007

Purpose

This study seeks to explore the incidence and severity of inconsistency in the application of disciplinary measures between supervisors, given the same disciplinary incident. Consistency is an important aspect of procedural fairness in disciplinary action, but it has received little empirical attention.

Design/methodology/approach

Four employee discipline scenarios were assigned at random to 130 real‐life supervisor‐employee dyads, who role‐played the scenario.

Findings

There was little consistency between supervisors in their decisions regarding disciplinary measures. Overall, having an informal discussion with the employee was the most common response. Only when specific instructions to impose a verbal or written warning were provided did most supervisors move beyond an informal discussion. Even when clear instructions were given, a substantial minority applied a less severe disciplinary outcome.

Research limitations/implications

Even in this role‐play situation, where “real life” variables such as union grievances that could lead to the dilution of disciplinary action were not present, supervisors were generally lenient regarding employee discipline.

Practical implications

The trade‐off between the objectives of consistency and consideration of individual circumstances presents a serious challenge to practising supervisors.

Originality/value

This is a rare empirical paper exploring the issue of consistency in employee discipline.
Assembly issues with Sn/Ag/Cu bumped flip chips
Authors: Gopakumar Sunil , Borgesen Peter , Srihari K.
Published: December 2007

Purpose

The objective of this research is to address issues that relate to the assembly of Sn/Ag/Cu bumped flip chips.

Design/methodology/approach

Flip chips bumped with Sn/Ag/Cu bumps were assembled onto different lead‐free surface finishes at lead‐free soldering temperatures. Sensitivity to fluxes, reflow profiles, pad finishes and pad designs were all investigated and the potential consequences for assembly yields were calculated numerically.

Findings

Soldering defects, such as incomplete wetting and collapse and poor self‐centring were observed in the assemblies. Defect levels were sensitive to contact pad metallurgy and flux type, but not to flux level and reflow profile within the ranges considered. Owing to a particularly robust substrate‐pad design, defects observed in this work were limited to incomplete wetting and collapse, as well as poor self‐centering.

Research limitations/implications

The scope of this work is limited to the lead‐free fluxes available at the time of research. A switch to lead‐free solder alloys in flip chip assemblies raises concerns with respect to the compatibilities of materials and the quality of soldering that is achievable. While this may be less of an issue in the case of larger area array components, such as ball grid arrays and chip scale packages, it is more of a concern for applications that use flip chips due to the smaller size of the solder spheres. Assembly yields tend to become more sensitive to the reduced collapse of the joints. More work is essential to investigate the potential benefits of more active lead‐free fluxes, both no‐clean tacky and liquid fluxes, in reducing or eliminating soldering defects.

Originality/value

The paper offers insights into assembly issues with Sn/Ag/Cu bumped flip chips.
Characterization of SnAgCu and SnPb solder joints on low‐temperature co‐fired ceramic substrate
Authors: Zhong Z.W. , Arulvanan P. , Phone Maw Hla , Lu C.W.A.
Published: December 2007

Purpose

The purpose of this paper is to present the results of experiments performed to attach silicon dies (chips) to low‐temperature co‐fired ceramic (LTCC) substrates with Ag or AgPd pads using SnAgCu or SnPb solder and the results of the characterization of the solder joints.

Design/methodology/approach

LTCC substrates were fabricated by stacking and laminating four green tapes with the top layer screen‐printed with Ag or AgPd paste to form pads. Silicon die sizes of 1 × 1 mm and 2 × 2 mm with electroless nickel immersion gold plated were soldered to 2 × 2 mm pads on the LTCC substrates using SnPb or SnAgCu solder. The solder joints were then characterized using X‐ray, die shear, energy dispersive X‐ray and scanning electron microscopy techniques.

Findings

The joints made by AgPd pads with SnAgCu solder provided the best results with the highest shear strength having strong interfaces in the joints. However, the joints of Ag pads with SnPb solder did not provide high‐shear strength.

Originality/value

The findings provide certain guidelines to implement LTCC applications. AgPd pads with SnAgCu solder can be considered for applications where small silicon dies need to be attached to LTCC substrates. However, Ag pads with SnAgCu solder can be considered for lead‐free solder applications.
Low cycle isothermal fatigue properties of lead‐free solders
Authors: Dušek Miloš , Hunt Christopher
Published: December 2007

Purpose

The purpose of this paper is to discuss a new method to measure the fatigue of single solder joints in shear, and hence calculate the joint strain energy density in each fatigue cycle.

Design/methodology/approach

There has been a step change in the requirement to characterise solder joint reliability with the number of new alloys introduced as a result of the recent RoHS legislation. Experimental testing for every configuration is expensive and time consuming, and hence modelling has become more attractive. The accuracy of modelling predictions is limited by the accuracy of the materials data. The data for these new alloys must reflect the miniaturisation of electronics and that solder joints are loaded in shear, two aspects not well reflected in the existing SnPb data. The approach here has been to develop an instrument interconnect properties test machine, where the strain and stress can be measured directly for small solder volumes and in shear. A four‐point measurement system for resistance monitoring has also been evaluated and found to correlate well with load decreases recorded during fatigue testing of solders, and hence provide a method to calculate the crack area.

Findings

The experiments have recorded the stress strain behaviour during isothermal fatigue. The developing crack area has been measured using an electrical resistance technique and has been used to correct the stress values. Using the corrected stress the strain energy data can be calculated.

Research limitations/implications

The work has been limited to a single alloy and a single joint configuration, with time these will be broadened and the experimental fatigue parameters extended.

Practical implications

These measurements will provide a route for calibrating the finite element models. A databank of material properties could be built up for alloys used in a range of configurations. This would help support and widen the use of modelling to predict fatigue life.

Originality/value

There is an increasing awareness of the importance of measuring microelectronic solder joint fatigue properties. There are a number of approaches being pursued, but the work at NPL is important in allowing the experiment to be controlled by either stress, strain or temperature, and with the added ability to measure crack area. This uniquely enables the measurement directly of the strain energy density during a fatigue experiment.
Organizational culture as a discriminating variable of export activities
Authors: Dosoglu‐Guner Berrin
Published: December 2007

Purpose

The paper's purpose is to identify the differences in organizational culture between exporting and non‐exporting firms.

Design/methodology/approach

A binary logit model is used to test organizational cultural differences in four different types; market culture, ad hocracy culture, clan culture, and hierarchy cultures. A univariate t‐test is also used to determine mean differences in organizational culture of exporting and non‐exporting firms.

Findings

Non‐exporting firms tend to be more customer‐driven and competitively oriented (market culture) than exporting firms. However, they are found to be more internally oriented (clan culture) than exporters. There are no significant differences for ad hocracy and hierarchy cultures.

Research limitations/implications

First, the study omits the effects of industry conditions in the firm's cultural orientation. Hence, industry factors need to be studied in relation to exports and organizational culture. Second, organizational culture may play a facilitating rather than predictive role in international expansion since managerial attitudes and characteristics can shape the vision of organizations. It is recommended that future research examine the relationships between managerial characteristics and organizational culture and how this relationship affects the firm's export decisions. Finally, a further classification of non‐exporting companies into interested and not‐interested firms is suggested to further the current literature.

Originality/value

The paper may help interested non‐exporters undertake an organizational change to align their organizational culture with the dynamics of international business so that they can become exporters.
Corporate bankruptcy prediction models applied to emerging economies
Authors: Sandin Ariel R. , Porporato Marcela
Published: December 2007

Purpose

The paper's aim is to test the usefulness of ratio analysis to predict bankruptcy in a period of stability of an emerging economy, such as the case of Argentina in the 1990s.

Design/methodology/approach

Financial profiles of 22 bankrupt and healthy companies are examined and a model is built using the multiple discriminant analysis technique, thus providing comparability with previous studies.

Findings

The set of models tested in this paper show that the financial data of Argentine companies in the 1990s do have information content, but the model to use depends on the preferences of the decision maker. Comparing models it is observed a common use of solvency ratios in terms of total assets and profitability ratios in terms of sales.

Research limitations/implications

Data availability constitutes the primary limitation of this and similar studies, here is reflected in the sample size: 11 healthy and 11 bankrupt.

Practical implications

The model can be used to assist investors, creditors, and regulators in Argentina and other emerging economies to predict business failure. The Z ′‐score model of Altman can be used for public companies in emerging economies because it pays attention to solvency indicators, but in rapid changing environment, profitability ratios should also be considered.

Originality/value

The incremental information content of profitability and solvency in predicting bankruptcy is examined and a simple and reliable failure prediction model for large Argentinean firms is developed. Also this paper offers a classification method that is publicly available to all investors and creditors interested in Argentinean companies.
An empirical investigation of users' views on corporate annual reports in Qatar
Authors: Alattar Jalal M. , Al‐Khater Khalid
Published: December 2007

Purpose

This study is the first attempt to explore in depth users' views on corporate annual reports in Qatar, which has a rapidly growing economy and underdeveloped accounting systems.

Design/methodology/approach

A questionnaire was distributed to 80 individual investors, 40 institutional investors, 30 financial analysts, 30 bank credit officers and 40 government officers who are involved with investment decisions. A total of 150 completed questionnaires were returned giving a response rate of 68 percent. Descriptive statistics and Kruskal‐Wallis and Mann Whitney tests were used to analyze the results.

Findings

The respondents considered annual reports to be important and useful and to be the main source of information for investment decisions. The respondents rated the balance sheet, auditor's report, cash flow statement, income statement and notes to the accounts as the most important and understandable sections in the annual reports. Additionally, respondents considered government publications and newspapers, magazines and journals to be very important sources of up to date, useful and easy to access information. Respondents differed significantly in their perceptions about the importance of the cash flow section, the use of accounting information for monitoring investment decisions and the use of other available sources of information.

Research limitations/implications

Findings reported in the paper reveal the need for research into the reasons for such differences and also may help accounting association bodies in Qatar to play an active role in improving users' awareness of the importance and usefulness of corporate annual reports when making investment decisions.

Originality/value

This project explores what sections of the corporate annual reports are most important to the users in the state of Qatar which has unique attributes in terms of its economic and accounting developments. Several findings are particularly relevant for preparers of corporate annual reports in this unique developing country. Although several studies investigated this issue in developing countries such as the Kuwait, Saudi Arabia, Bahrain, Jordan and Iran, the findings of these studies might not be generalized on Qatar.
Relationships among industry environment, diversification motivations and corporate performance
Authors: Tan Bertram , Chang Hae‐Ching , Lee Chen‐Kuo
Published: December 2007

Purpose

This paper aims to examine empirically the relationships among industry environment, diversification motivations and corporate performance for a sample of Taiwanese automobile enterprises.

Design/methodology/approach

A 55‐item survey questionnaire was developed to obtain the responses from companies in the automobile industry in Taiwan. Independent sample t‐test and χ2 tests were employed to confirm the homogeneity between the respondents and non‐respondents by firm's characteristics, including by industry, number of employees, and capital.

Findings

The results suggest that industry environment has positive and significant impact on diversification motivations, and has positive but not significant impact on corporate performance. Diversification motivations has positive and significant impact on corporate performance. The results also indicate that firms of higher capital amounts have greater influence on diversification motivations and corporate performance, firms of publicly listed have greater influence on industry environment, diversification motivations and corporate performance and firms of higher degree of diversification have greater influence on diversification motivations only.

Research limitations/implications

Several limitations exist in this study. This study adopts the cross‐sectional research design and examines firms at one point time and because of the constraints of time and data availability, longitudinal research was not viable in this study. Also the amount of variation for some regression models is low.

Originality/value

The paper's results not only provide researchers with a theoretical basis for further research, but also provide top management teams with important data when engaging in diversification.
Sale‐and‐leaseback as a British real estate model
Authors: Tipping Malvern , Bullard Richard K.
Published: December 2007

Purpose

Many established trading companies have had considerable capital value locked into their operational properties. These properties have been identified as producing lower returns on invested capital than core business activities. Consequently, there has been a growing trend for the splitting of operational property from core business activity. This paper seeks to identify trends in sale‐and‐leaseback, which is the most common model in the UK.

Design/methodology/approach

This paper reviews, the existing literature and some past transactions in order to identify the motivations of both operational businesses and property investors in adopting the model. Some transaction case studies are also highlighted.

Findings

Identification of the motives behind this approach. Accounting, taxation and capital release are identified as the main drivers when the model first became widespread in the UK two decades ago. It is now driven by taxation and capital release. Originally adopted by leading companies, sale‐and‐leaseback has more recently been used by weaker covenants. The model has remained popular with investors, but there have been some recent failures.

Originality/value

This paper examines recent trends and seeks to identify how the sale‐and‐leaseback model may develop in the UK. Furthermore, the application of the model in the UK may give some insight into its application in other parts of the world, where it is either gaining further acceptance or may have greater potential application.
Corporate real estate management (CREM) in Estonia
Authors: Ilsjan Veronika
Published: December 2007

Purpose

The purpose of this paper is to identify the development trends of corporate real estate management (CREM) in Estonia and to compare them with more developed western countries in order to define the actual problems.

Design/methodology/approach

An explorative survey with direct interviews among the 17 largest organisations in a certain sector (four banks, five infrastructure companies, five universities, three municipalities).

Findings

In some fields Estonia recovered from the lost experience stages quickly (organisational structure and outsourcing), while in other fields it has not yet recovered (disposal of owned properties), but in several aspects the problems are similar to western countries (information issues). No differences are found between the public and private sectors or between larger and smaller organisations. The smallness could be regarded as an advantage at the organisational and state levels since it allows for better communication, but requires more flexibility. Strategies and tools justified in more developed markets and in larger organisations could limit development in a smaller environment and therefore, should not be transferred automatically.

Research limitations/implications

The office sector was selected for a comprehensive but comparable overview for several reasons.

Originality/value

Practically no CREM research has been conducted in either Estonia or any other Eastern European country. Estonia lost about half a century's experience of the open market environment during the Soviet period (1945‐1990), when there was no private ownership of enterprises and properties. Since the second‐half of the 1990s the economy, and especially the property market in Estonia have risen rapidly. Estonia could be handled as a representative example (case) to explore CREM development in countries with a similar history.
Left Atrial Systolic Performance in the Presence of Elevated Left Ventricular End‐Diastolic Pressure: Evaluation by Transesophageal Pulsed Doppler Echocardiography of Left Ventricular Inflow and Pulmonary Venous Flow Velocities
Authors: OKI TAKASHI , FUKUDA NOBUO , IUCHI ARATA , TABATA TOMOTSUGU , TANIMOTO MASATO , MANABE KAZUYO , KAGEJI YOSHIMI , SASAKI MIWA , YAMADA HIROTSUGU , ITO SUSUMU
Published: December 2007

We recorded left ventricular inflow (LVIF) and pulmonary venous flow (PVF) velocities by trans‐esophageal pulsed Doppler echocardiography in 25 patients with a ratio of peak atrial systolic to early diastolic LVIF velocity of < 1 and a left ventricular end‐diastolic pressure (LVEDP) of 15 mmHg or greater, as well as in 30 normal subjects. The group consisted of 14 patients with prior myocardial infarction, 7 with dilated cardiomyopathy, and 4 with cardiac amyloidosis, and were divided into: (1) group A (n = 7): peak atrial systolic LVIF velocity of 40 cm/sec or greater; (2) group B (n = 7): peak atrial systolic LVIF velocity of < 40 cm/sec and peak atrial systolic PVF velocity of 30 cm/sec or greater; and (3) group C (n = 11): peak atrial systolic LVIF velocity of < 40 cm/sec and peak atrial systolic PVF velocity of < 30 cm/sec. Although LVEDPs in groups B and C were significantly greater than in group A, there was no difference between groups B and C. The mean pulmonary capillary wedge pressure (mPCWP) in group C was significantly greater than in groups A and B, but there was no difference between groups A and B. The difference between LVEDP and mPCWP (LVEDP — mPCWP) in group B was significantly higher than in groups A and C. Dilatation of the left atrium (LA) was seen in all three groups, particularly in groups B and C. There were no differences in peak atrial systolic LVIF velocity and LA volume change during atrial contraction between group A and the control group, and there were no differences in LA volume change and peak second systolic PVF velocity between groups A and B. LA volume change and peak second systolic PVF velocity were significantly less in group C than in groups A and B. Among the four patients whose courses could be observed after medical treatment with diuretic and vasodilator, one changed from group B to A, one from group B to C, one from group C to A, and one remained in group C. Thus, recording of peak atrial systolic LVIF and PVF by transesophageal pulsed Doppler echocardiography permits detailed evaluation of LA systolic performance in the presence of elevated LVEDP. These two variables provide important information for less invasive differentiation of LA afterload mismatch from LA myocardial failure.
Stimulated Acoustic Emission: Nonbackscatter Contrast Effect of Microbubbles Seen with Harmonic Power Doppler Imaging
Authors: TIEMANN KLAUS , BECKER HARALD , BIMMEL DIETER , SCHLIEF REINHARD , NANDA NAVIN C.
Published: December 2007

Transient imaging has been introduced to enhance the signal intensities when using echo contrast agents. However, this phenomenon is not clearly understood. To evaluate the mechanisms of this phenomenon, isolated pig hearts were investigated with different echo imaging techniques in the beating, working heart as well as in an asystolic state without any motion of the heart. The hearts of five German farm pigs (21 ± 2.5 kg) were surgically explanted and inserted in an artificial circulation providing physiological flow and pressures. Levovist in the dosage of 0.05–0.3 g was injected into the left atrium and contrast effects evaluated in the left ventricular (LV) cavity and in the myocardium with an ultrasound imager (ATL, HDI 3000) equipped with a prototype software for harmonic imaging. Harmonic B‐scans and power Doppler registrations were performed with continuous and intermittent recordings (ECG triggered at end‐systole) in the beating heart and using an external trigger in the asystolic heart in which perfusion was interrupted for 20 seconds. In the beating pig heart, transient harmonic power Doppler imaging provided intensive opacification of the LV cavity and visible myocardial uptake when ECG triggering was performed. In the asystolic pig heart, with uninterrupted perfusion, both triggered and nontriggered registrations showed contrast signals in the LV cavity and in the myocardium. These findings cannot be explained with the known physics of ultrasound contrast media. Stimulated acoustic emission occurring during disintegration of the microbubbles in the acoustic field would explain this phenomenon, which has not yet been described for Levovist.
Practical Approach to a Digital Echocardiographic Laboratory
Authors: FEIGENBAUM HARVEY
Published: December 2007

Routine digital storage of echocardiograms offers considerable advantages over video tape, including random access to images within a study, side‐by‐side comparison with prior studies, and duplication and transmission of images without degradation. The massive storage requirements for complete echo studies has discouraged many laboratories from adopting digital storage, but through judicious use of “clinical compression” routine digital echocardiography can be a reality today. By limiting storage to quad screen displays of images, it is possible to store the most relevant data from an examination in just a few megabytes.
Absent Pulmonary Valve: Echocardiographic Features
Authors: PACHIRAT ORATHAI , SEWARD JAMES B. , O'LEARY PATRICK W.
Published: December 2007

Congenital absence of the pulmonary valve, a rare anomaly, is characterized by absent or rudimentary pulmonary valve, often with annular stenosis, and aneurysmal dilatation of the pulmonary arteries. This defect is most commonly an accompaniment of tetralogy of Fallot but occasionally occurs alone. Four patients with this abnormality were examined by two‐dimensional echocardiography at the Mayo Clinic. Doppler echocardiography provided hemodynamic assessment of the magnitude of outflow obstruction and valve regurgitation. The two‐dimensional echocardio‐graphic and Doppler features of absent or rudimentary pulmonary valve provided diagnostic information sufficient to proceed directly to surgical correction.
Doppler Study of Transmitted Transmitral A Wave in Patients with a Fourth Heart Sound
Authors: VOON WEN‐CHOL , SHEU SHENG‐HSIUNG , HWANG YUH‐YAU
Published: December 2007

To investigate the characters of the transmitted transmitral A wave associated with a fourth heart sound, left ventricular inflow, and outflow Doppler echocardiography and phonocardiography were recorded in 13 patients with a fourth heart sound and 9 age‐matched control subjects. The Doppler echocardiographic data were compared between both groups and the peak velocity and acceleration rate of the transmitted transmitral A wave were correlated with other parameters.

The peak velocity and acceleration rate of the transmitted transmitral A wave were significantly greater, but the A wave transit time from the mitral valve to the left ventricular outflow tract (A‐Ar interval) was significantly shorter in patients with a fourth heart sound. There was a significant correlation between the A‐Ar interval and the peak velocity (r = ‐0.54, P = 0.01) or acceleration rate (r = ‐0.63, P = 0.002) of the transmitted transmitral A wave. The A‐Ar interval was shown to be the independent determinant of both the peak velocity and acceleration rate of the transmitted transmitral A wave by stepwise multiple linear regression. In conclusion, the presence of a fourth heart sound was associated with a higher peak velocity and acceleration rate of the transmitted transmitral A wave, to which increased ventricular stiffness may make some contributions.
Prediction of Intraoperative Hypovolemia in Patients with Left Ventricular Hypertrophy: Comparison of Transesophageal Echocardiography and Swan‐Ganz Monitoring
Authors: ÇIEK SERTAÇ , DEMIRKILIÇ UFUK , KURALAY ERKAN , ARSLAN MEHMET , TATAR HARUN , ÖZTÜRK ÖMER Y.
Published: December 2007

We have compared the pulmonary artery catheterization and transesophageal echocardiography (TEE) as an index of left ventricular (LV) volume in 32 patients with LV hypertrophy. Twenty‐four of the 32 patients had episodes of low LV volume using TEE. Of these 24 patients, five had low pulmonary capillary wedge pressures ranging from 6–11 mmHg (mean ± SD, 8.8 ± 1.9 mmHg). Nineteen patients had elevated pulmonary capillary wedge pressures (PCWPs) (mean 18.3 ± 2.2 mmHg) and TEE showed signs of hypovolemia. Volume repletion resulted in increased blood pressure in these patients. The poor correlation between PCWP and LV end‐diastolic volume in the present study may result from impaired compliance of the ventricle. Diagnosis of hypovolemia should not be solely based on hemodynamic parameters alone and TEE provides accurate estimates of ventricular volume.
The Role of Echocardiography in the Management of Patients with Massive Pulmonary Embolism
Authors: HARRIS KEVIN M. , MUIR J. CAMERON , HANEY MICHAEL F. , PLEHN JONATHAN F.
Published: December 2007

Acute massive pulmonary embolus (PE) when undiagnosed may lead to hemodynamic compromise and death. Echocardiography offers several clues to the diagnosis of PE. We describe how transesophageal echo was used in the diagnosis and management of two patients with this disorder.
Rapid Development of a Papillary Fibroelastoma with Associated Thrombus: The Role of Transthoracic and Transesophageal Echocardiography
Authors: JOFFE IAN I. , JACOBS LARRY E. , OWEN ALYSON N. , IOLI ALFRED , KOTLER MORRIS N.
Published: December 2007

Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) are frequently utilized in patient's with suspected cerebral vascular ischemia. We describe a patient with suspected cerebral vascular ischemic event whom was found to have a mobile valvular mass by TTE and TEE. The lesion was unusual due to its rapid development over a period 6 months, which was documented on serial echocardiography. The mass was excised surgically and pathology showed a papillary fibroelastoma with extensive thrombus. The differential diagnosis of a cardiac valvular mass and the treatment of cardiac fibroelastomas are reviewed. In this case, both TTE and TEE were valuable in diagnosis and facilitating surgical management of a cardiac fibroelastoma.
Transesophageal Echocardiographic Detection of Malignant Lymphoma
Authors: HANSEN TODD H. , TARVER ROBERT D. , SEGAR DOUGLAS S.
Published: December 2007

Transesophageal echocardiography (TEE) is an excellent method for visualizing pathology of the mediastinum. We present a case in which TEE detected an unsuspected lymphoma posterior to the descending thoracic aorta in a man suspected of having endocarditis. This case illustrates the advantages of TEE over transthoracic echocardiography in examining the mediastinum and the importance of performing a complete TEE examination.
Identification of Perfusion Abnormalities Using FSO69, a Novel Contrast Agent, in Conscious Dogs
Authors: MOBAREK SAMEH , KATES MARC , MEZA MARIO , MORENO CARLOS , REVALL SUSAN , BARBEE WAYNE , MURGO JOSEPH P. , CHEIRIF JORGE
Published: December 2007

Recent advances in the production of echocardiographic contrast agents has resulted in the ability to delineate areas of hypoperfusion after coronary occlusions and stenoses following their intravenous injection. Most of these studies though have been done in open chest animals. This study was done to determine if we could assess myocardial perfusion following the intravenous administration of FSO69, a suspension of perfluoropropane filled albumin microspheres (3.6 μm average microbubble size, concentration 8 × 108), in spontaneously breathing closed chest dogs. Twenty‐seven mongrel dogs were instrumented on day 1. The chest was then closed and the dogs were restudied 3–7 days later, while spontaneously breathing. Homogeneous perfusion was observed in most dogs by all three independent and blinded observers. Perfusion abnormalities were likewise identified in most instances by all blinded reviewers on interventions designed to decrease regional blood flow. A good correlation between perfusion defect size between investigators was observed. In summary, our data suggest that FSO69 can be used to assess regional myocardial perfusion in spontaneously breathing dogs. These results support its use in humans.
Prediction of Homograft Aortic Valve Size by Transthoracic and Transesophageal Two‐Dimensional Echocardiography
Authors: FAN CHAO MEI , LIU XING , PANIDIS JOHN P. , WIENER DAVID H. , POLLACK PIA S. , ADDONIZIO V. PAUL
Published: December 2007

To avoid the problem of patient valve mismatch we assessed the reliability of echocardiographic measurements in selecting an appropriate‐sized homograft aortic valve. Preoperative transthoracic echocardiography (TTE) was performed in 26 consecutive patients undergoing aortic valve replacement with a cryopreserved human homograft; 19 of the patients also had intraoperative transesophageal echocardiography (TTE). The diameters of left ventricular outflow tract (LVOT), aortic annulus, sinuses of Valsalva, and ascending aorta were measured by the same technique in all patients. There was a strong correlation between LVOT diameter measured by intraoperative TEE and homograft aortic valve size selected by the surgeon (r = 0.91, P < 0.001). A good correlation was also found between LVOT measured by preoperative TTE and the homograft valve size (r = 0.82, P = 0.001). The correlation between the homograft aortic valve size and the diameter of aortic annulus was less optimal; the correlation was poor for the diameter of aorta measured at the level of the sinuses of Valsalva and ascending aorta. Measurement of the LVOT diameter by intraoperative TEE and preoperative TTE is reliable and clinically useful for the preparation of homograft aortic valves and selection of proper size, particularly in those patients undergoing repeat aortic valve replacement, with heavily calcified aortic valve or with ascending aortic aneurysm.
Improved Assessment of Pathological Regurgitation in Patients with Prosthetic Heart Valves by Multiplane Transesophageal Echocardiography
Authors: KUPFERWASSER IRI , MOHR‐KAHALY SUSANNE , ERBEL RAIMUND , NOLTING AXEL , DOHMEN GUIDO , OELERT HELLMUT , MEYER JÜRGEN
Published: December 2007

The aim of this study was to evaluate the diagnostic increment of individually optimized axes in the assessment of pathological prosthetic valve regurgitation. Forty‐two patients with pathologically regurgitant prostheses in the aortic (n = 21), mitral (n = 15), and tricuspid (n = 6) positions were examined by multiplane transesophageal echocardiography. The investigation was performed utilizing the transverse axis first, the longitudinal axis second, and the intermediate axes afterwards. The presence of regurgitation, the differentiation between trans‐ and perivalvular origin, and the localization of perivalvular leakages at the sewing ring were evaluated. Findings in the biplane and intermediate axes were compared to surgery or autopsy in all patients. There was slightly higher detection rate for aortic prosthetic regurgitation using the intermediate axes than the biplane axes. The intermediate axes revealed significantly fewer differences to the morphological control than the biplane axes with regard to the differentiation of peri‐ and transprosthetic aortic regurgitation and to the localization of a periprosthetic aortic regurgitant origin. The intermediate axes provided significantly better agreement to surgery/autopsy than the biplane axes regarding the localization of the origin of mitral periprosthetic regurgitation. Morphological visualization of the perivalvular gap adds important information on the precise localization of the regurgitant origin. The pathological gap was visualized significantly more often using the intermediate than the biplane axes in all types of prostheses. The data in this study therefore suggest that multiplane transesophageal echocardiography is superior to biplane transesophageal echocardiography in the assessment of pathologic prosthetic regurgitation.
Dynamic Left Ventricular Outflow Tract Obstruction During Myocardial Ischemia in Mitral Valve Prolapse Syndrome
Authors: DE CONTI FABIO , PIOVESANA PIERGIUSEPPE , NICOLOSI GIANLUIGI , LAFISCA NICOLÒ , MANTOVANI ENZO , VIENA PIETRO , PANTALEONI ATTILIO
Published: December 2007

Systolic anterior motion of the mitral valve (MV) with dynamic left ventricular (LV) outflow tract obstruction is a well known phenomenon in hypertrophic cardiomyopathy, or other forms of hyper‐dynamic LV function associated with hypovolemic states, or LV hypertrophy. We report three patients with MV prolapse in the absence of the above predisposing factors, who developed an LV outflow dynamic gradient during acute transient myocardial ischemia. An interaction between structural abnormalities of the mitral apparatus and ischemia‐dependent LV shape deformity most likely accounted for the outflow gradient.
Diagnosis of Supravalvular Aortic Stenosis by Transesophageal Echocardiography
Authors: SUBAHI SAAD A. , NOUH MOHAMMED S. , ALLAM ABDULKADER R. , AKHTAR M. JAWAID
Published: December 2007

The role of transesophageal echocardiography (TEE) in diagnosis of disorders of the thoracic aorta is well established. In this report the TEE findings in an adult patient with supravalvular aortic stenosis are presented. This showed narrowing of the ascending aorta just above the sinuses, due to fibromuscular thickening, causing an hour‐glass shaped deformity. The excellent image quality obtained by TEE is far superior to transthoracic echocardiography. Coronary artery ostial obstruction a known association of supravalvular aortic stenosis can be caused by different mechanisms including adherence of the aortic valve leaflet to the ridge of obstructive muscle or premature atherosclerosis. TEE can define the mechanism of coronary artery ostial obstruction associated with supravalvular aortic stenosis.
Gender Differences in Mitral Inflow Parameters of Doppler Echocardiography
Authors: SADANIANTZ ARA , HADI BETSY J. , LAURENT LINDA SAINT
Published: December 2007

Background: Doppler echocardiographic parameters are useful in understanding cardiac function. Previous studies have evaluated the physiologic effects of heart rate, body position, and age on left ventricular (LV) Doppler inflow variables. Objective: The aim of this study was to investigate the effect of gender on LV Doppler inflow variables. Methods: A complete echocardiographic study was performed in the left lateral position on 25 male and 25 female normal subjects. The Doppler variables, of E and A wave velocities, acceleration and deceleration times of the E wave velocity, and cardiac chamber dimensions were measured. Results: The aortic root size (3.2 ± 0.4 vs 2.8 ± 0.4 cm, P = 0.002), LV end systolic (2.8 ± 0.3 vs 2.5 ± 0.5 cm, P = 0.03), and LV end diastolic dimensions (5.0 ± 0.4 vs 4.5 ± 0.6 cm, P = 0.003) were larger in men compared to women. E wave deceleration time (233 ± 40 vs 197 ± 37 msec, P = 0.002) was longer in men compared to women. Using univariate analysis, deceleration time of the E wave was correlated with heart rate (P = 0.001), maximal A wave velocity (P = 0.007), acceleration time of the E wave (P = 0.01), LV systolic dimension (P = 0.03), maximal E wave velocity (P = 0.04), LV diastolic dimension (P = 0.06), and height (P = 0.07). E/A ratio, body surface area, age, weight, and left atrial dimension had no signifant correlation with the deceleration time of the E wave. In the multivariate model, heart rate (P = 0.001) had the most significant (inverse) correlation with deceleration time of the E wave. Conclusions: In this cohort of subjects, there were signifcant differences in LV systolic and diastolic measurements and Doppler measurements of deceleration time of the E wave between men and women. The differences in Doppler measurements between men and women are most likely affected by the higher heart rate in women. Therefore, when interpreting deceleration time of the E wave, the effect of heart rate should be considered.
Differences in Myocardial Contrast Produced with Transient Response Imaging When Using Intravenous Microbubbles Containing Gases of Different Molecular Weight
Authors: PORTER THOMAS R. , XIE FENG , LI SHOUPING
Published: December 2007

The purpose of this study was to determine the effect of different microbubble gases on the amount of myocardial contrast (MC) produced from intravenously (IV) injected dextrose albuinin microbubbles when using a new imaging modality termed transient response imaging (TRI). In 6 dogs (4 closed chest, 2 open chest) the peak anterior myocardial videointensity (PMVI) and visual degree of MC were determined following IV injections of equivalent doses of perfluorocarbon exposed sonicated dextrose albumin (PESDA), sulfur hexafluoride‐exposed sonicated dextrose albumin (SHESDA), and room air exposed sonicated dextrose albumin (RASDA) microbubbles. TRI was performed by triggering ultrasound impulses to 1 point every one to two cardiac cycles. The PMVI produced with TRI was compared to conventional 30 Hz frame rate imaging (CI) for each gas. Visual anterior and posterior MC was evident with TRI in all six dogs using PESDA, but not in any dog with CI. Although RASDA and SHESDA did not produce MC with CI, visually evident anterior MC was seen after 7 of 8 SHESDA and 4 of 9 RASDA injections when using TRI with both gases. PESDA produced the higest peak PMVI of all three microbubbles when using TRI, while SHESDA produced a significantly higher PMVI than RASDA. We conclude that although MC can be produced with TRI using microbubble gases of lower molecular weight, the brightest and most consistent contrast is produced with fluorocarbon containing microbubbles.
Right Ventricular Outflow Tract Tumor Mimicking a Thrombus in the Main Pulmonary Artery
Authors: AMUCHASTEGUI LUIS M. , MARANI LEANDRO P. , CAEIRO ANDRES
Published: December 2007

Primary sarcomas of the pulmonary artery and right ‘ventricle are rare, and their presentation is unusual in clinical practice; therefore, their diagnosis is often missed or delayed. The progression of the obstruction from the outflow tract of the right ventricle to the pulmonary artery resembles massive pulmonary embolism. We present a case of one of these tumors which mimicked transesophageal echocardiography (TEE), a massive pulmonary embolism. We conclude that TEE represents a non‐invasive method of diagnosis and evaluation when the suspicion is massive pulmonary thromboembolism or a heart tumor.
Valve Resistance in Mitral Stenosis
Authors: HENRIQUE WEITZEL LUÍS , LIMA DE MARCA WEITZEL EVANICE , NEVAL MOLL FILHO JORGE
Published: December 2007

To evaluate the value and the determinants of valve resistance in mitral stenosis, 95 patients with pure mitral stenosis were examined by Doppler echocardiography during their clinical follow‐up, measuring cavity dimensions, left ventricular function, mitral area (by planimetry and pressure half time), mean transmitral pressure gradient, aortic flow, and pulmonary artery systolic pressure. The mitral resistance was calculated as mean transmitral pressure gradient/aortic flow ratio. To graduate the severity of the morphological abnormalities in valvular structure, we used a point score system with evaluation of leaflet and subvalvular thickness, calcification, and valvular mobility. The functional class was determined according to NYHA classifcation. In this study, both mitral area (r = ‐0.79, P < 0.001 and rp= ‐0.60, P < 0.001) and mitral score (r = 0.68, P < 0.001 and rp= 0.25, P = ‐0.013) were independent determinants of mitral resistance. In multivariate analysis, mitral resistance and female gender were selected by multiple linear regression analysis as determinants of pulmonary artery systolic pressure, and mitral area and pulmonary artery systolic pressure were selected by logistic linear regression analysis as determinants of NYHA functional class. In patients with moderate or severe mitral stenosis, the estimated probability for III and IV NYHA functional class considering mitral area 1 cm2 or below went from 51.1–86.4% when mitral resistance below or above 130 dynes.sec.cm,−5 respectively, was considered together. Thus, mitral valve resistance should be used as a complement to the mitral area method in assessment of mitral stenosis, adding the effects of the reduction in mitral area and the damage in mitral valve apparatus.
Quantification of Atherosclerotic Burden in the Descending Aorta by Transesophageal Echocardiography
Authors: KHOURY ZAHI , RINAT CHONI , BENHORIN JESAIA , STERN SHLOMO , KEREN ANDRE
Published: December 2007

Atherosclerotic plaques had been imaged but not quantitated in the thoracic aorta using transesophageal echocardiography. The aim of this study was to describe a method for measuring the atherosclerotic plaque area in the descending aorta by transesophageal echocardiography (TEE) and to evaluate its reproducibility. TEE examinations were performed by two independent sonographers, in 21 patients with angiographically proven coronary artery disease. Two hundred fifty‐six transverse segments (mean 12 ± 3 patient) of the descending aorta were adequately recorded. In each segment the plaque and the lumen areas in the half of the aortic segment distant from the transesophageal probe were measured by one reader in the two studies (intersonographer reproducibility). Interreader reproducibility was also evaluated. The correlation coefficient between the first and second study (intersonographer reproducibility) was 0.81. The standard deviation of the difference between examinations equaled 0.137 cm2 and the mean absolute difference between examinations was 0.003 cm2 (95% CI: –0.015; 0.021; P = 0.75). The correlation coefficient between the two readers was 0.86, the standard deviation of the difference between readers was 0.175 cm2 and the mean absolute difference was 0.006 cm2 (95% CI: –0.029; 0.018; P = 0.63). A method for quantitative measurement of aortic atherosclerotic plaque area was evaluated and found to have high intersonographer and intereader reproducibilities. This method might be used in the future for noninvasive evaluation of regression or progression of aortic atherosclerosis.