bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudoaneurysm of the Mitral‐Aortic Intervavular Fibrosa: A Long‐Term Complication of Infective Endocarditis
Authors: AGIRBASLI MEHMET , FADEL BAHAA M.
Published: December 2007

Pseudoaneurysms of the left ventricle are rare and may occur as a result of transmural myocardial infarction, chest trauma, cardiac surgery, or endocarditis. Although postinfarction pseudoaneurysms commonly arise in the mid and apical segments of the left ventricle, those resulting from endocarditis arise at the base of the heart. Here we report the case of a patient who developed a large pseudoaneurysm as a complication of aortic valve endocarditis. The pseudoaneurysm had two uncommon features; it originated from the intervalvular fibrous body connecting the mitral to the aortic valve, and it eroded through the chest wall, resulting in blood drainage through the skin.
Eustachian Valve Endocarditis in an Elderly Woman
Authors: PUNZO FRANCESCO , GUARINI PASQUALE , DE MICHELE MARIO , ACCADIA MARIA , IRACE LUIGI , CARUSO AURELIO , CORIGLIANO GIUSEPPE GRANATO
Published: December 2007

We describe the transesophageal echocardiographic findings in Eustachian valve endocarditis for a 73‐year‐old woman with a previous history of mitral valve disease. After a 4‐week treatment with antibiotics, follow‐up echocardiographic examination showed a smaller vegetation.
Failure of Serial Electrocardiograms to Exclude a Large Anterior Myocardial Infarction and the Role of Transesophageal Echocardiogram in Acute Myocardial Infarction
Authors: WANG YILI , CHEIRIF JORGE , MEYER STEVEN , KNOCHEL JAMES , TILL MARK
Published: December 2007

When patients present with acute onset of chest pain suggestive of myocardial ischemia, immediate clinical decisions regarding thrombolysis, percutaneous transluminal coronary angioplasty, or both are usually based on the history and abnormal electrocardiograms and confirmed by the presence of abnormally elevated cardiac enzymes. However, there are potential limitations of the electrocardiograms and initial cardiac enzymes in the diagnosis and confirmation of acute myocardial infarction. We describe the case of a patient who presented with an acute onset of chest pain and had a normal electrocardiogram and initial cardiac enzymes yet was found by transesophageal echocardiography to have a large myocardial infarction.
Echocardiographic Recognition of Left Ventricular Mural Thrombus
Authors: BARBERA SAVERIO , HILLIS L. DAVID
Published: December 2007

Left ventricular (LV) mural thrombus is a well recognized complication of acute myocardial infarction. In survivors of infarction, its incidence is influenced by the location and magnitude of infarction: it occurs often in patients with large anterior Q wave infarctions, particularly in the presence of LV apical akinesis or dyskinesis. Although radionuclide imaging with indium‐111‐labeled platelets, computed tomography, and magnetic resonance imaging may be used to identify LV mural thrombus, two‐dimensional echocardiography is the technique of choice for assessing its presence, shape, and size, and recent technical advances in echocardiographic methodology, such as high‐frequency, short‐focal‐length transducers, have improved the echocardiographic assessment of LV mural thrombus. In the patient in whom a mural thrombus is identified, acute and chronic anticoagulation (with heparin and warfarin, respectively) is indicated: first, to prevent further thrombus formation and, second, to reduce the incidence of systemic embolization.
Strain Rate Imaging by Ultrasound in the Diagnosis of Regional Dysfunction of the Left Ventricle
Authors: STOYLEN ASBJORN , HEIMDAL ANDREAS , BJORNSTAD KNUT , TORP HANS G. , SKJAERPE TERJE
Published: December 2007

Background: Regional strain rate in the left ventricle can be assessed by tissue Doppler velocity gradient and color mapped in real time. Regional contractility thus can be visualized and graded. To validate the method, we made a comparison with standard echocardiography. Methods and Results: Fifteen patients with recent myocardial infarction were examined with the use of strain rate imaging (SRI). Velocity gradients were mapped by color. Gray‐scale imaging was performed using the second harmonic mode. Cine loops of two‐dimensional echocardiography (2‐D echo) and SRI images from three standard apical planes were analyzed offline. A four‐grade scale in 16 segments was used to score wall motion by 2‐D echo and by SRI. Of a total of 236 segments, 235 segments were analyzable by 2‐D echo and 218 segments were analyzable by SRI. Correlation of wall motion score index with ejection fraction was – 0.84 by 2‐D echo and – 0.92 by SRI. One hundred fourteen segments had an equal score by the two methods: 51 segments differed by 1 degree and 14 segments differed by 2 degrees (K = 0.45). Conclusions: SRI agrees well with echocardiography in grading regional wall function, and the method can be seen as validated in a clinical setting for assessment of regional systolic wall function and is demonstrated to be applicable for semiquantitative wall motion assessment. SRI has theoretical advantages and may be a valuable addition to standard echocardiography, especially in the field of stress echocardiography.
Reproducibility of Brachial Artery Ultrasound Measurements
Authors: HATA AKIHIRO , REID CHERYL L. , OGATA TORU , TOKUSHIMA TAKASHI , GARDIN JULIUS M.
Published: December 2007

Recent findings suggest that systemic artery endothelial function is associated with the preclinical phase of vascular disease and related to traditional atherosclerosis risk factors. Brachial artery diameter changes in response to hyperemia have been proposed recently as a noninvasive tool to assess endothelial function. To evaluate the reproducibility of brachial artery diameter measurements using ultrasound, we studied 12 healthy subjects (eight men and four women, mean age 37 ± 9 years). An ATL HDI 3000 machine with a 5‐ to 10‐MHz broadband transducer was used to image the right brachial artery at rest, approximately 4 cm above the elbow. Gray scale ultrasound and color Doppler long‐axis images were recorded. Brachial arterial outer diameter (i.e., from anterior adventitia to posterior adventitia) and inner diameter (i.e., from anterior lumen‐intima interface to posterior lumen‐intima interface) were measured in each subject by two observers. An offline analysis system was used to make measurements at end‐diastole from four cardiac cycles. Interobserver and intraobserver measurement variabilities (technical error rates) for brachial artery inner diameter were excellent, ranging from 2.5% to 3.8%. However, interobserver technical error rates for outer diameter measurements were significantly greater than those for inner diameter measurements, ranging from 16.3% to 22.1% (P < 0.001), presumably related to the difficulty in accurately defining the adventitial lines. There were no significant differences in interobserver and intraobserver variability for measurements made using gray scale and color Doppler‐aided techniques. We conclude that interobserver and intraobserver reproducibility for brachial artery inner diameter measurements made from ultrasound images is excellent.
Toxic Methemoglobinemia Complicating Transesophageal Echocardiography
Authors: STOIBER THOMAS R.
Published: December 2007

We describe the case of a patient with acute methemoglobinemia after topical oropharyngeal anesthesia with benzocaine spray.
Lambl's Excrescences (Valvular Strands)
Authors: VOROS SZILARD , NANDA NAVIN C. , THAKUR ABHASH C. , WINOKUR THOMAS S. , SAMAL ADITYA K.
Published: December 2007

We review the literature on Lambl's excrescences (valvular strands). With the widespread use of cardiac imaging modalities, most importantly, with transesophageal echocardiography, abnormal valvular structures are frequently identified on both native and prosthetic heart valves. However, there is no consensus in the literature on the correct terminology of these structures. The relationship between valvular strands (the so‐called Lambl's excrescences) and papillary fibroelastomas has not been well established. In this review, we attempt to summarize the available echocardiographic descriptors and the gross macroscopic and histological features of Lambl's excrescences (valvular strands). In addition, we review the etiology, pathogenesis, and clinical implications of these cardiac excrescences. Also, we describe features that help to distinguish between Lambl's excrescences and papillary fibroelastomas. Because valvular strands (Lambl's excrescences) have been implicated in systemic thromboembolism, we also review the available management principles for patients with valvular strands; unfortunately, no specific therapeutic guidelines can be proposed at the present time.
Echocardiographic Doppler Evaluation of Left Ventricular Diastolic Filling in Older, Highly Trained Male Endurance Athletes
Authors: JUNGBLUT PETER R. , OSBORNE JASON A. , QUIGG REBECCA J. , MCNEAL MICHAEL A. , CLAUSER JOSEPH , MUSTER ALEXANDER J. , McPHERSON DAVID D.
Published: December 2007

Previously published data have suggested that endurance training does not retard the normative aging impairment of early left ventricular diastolic filling (LVDF). Those studies, suggesting no effect of exercise training, have not examined highly trained endurance athletes or their LVDF responses after exercise. We therefore compared LVDF characteristics in a group of older highly trained endurance athletes (n= 12, mean age 69 years, range 65–75) and a group of sedentary control subjects (n= 12, mean age 69 years, range 65–73) with no cardiovascular disease. For all subjects, M‐mode and Doppler echocardiographic data were obtained at rest. After baseline studies, subjects underwent graded, maximal cardiopulmonary treadmill exercise testing using a modified Balke protocol. Breath‐by‐breath respiratory gas analysis and peak exercise oxygen consumption (VO2max) measurements were obtained. Immediately after exercise and at 3–6 minutes into recovery, repeat Doppler echocardiographic data were obtained for determination of LVDF parameters. VO2max (44 ± 6.3 vs 27 ± 4.2 mllkglmin, P< 0.001), oxygen consumption at anaerobic threshold (35 ± 5.4 vs 24 ± 3.8 mllkglmin, P< 0.001), exercise duration (24 ± 3 vs 12 ± 6 minutes, P< 0.001), and left ventricular mass index (61 ± 13 vs 51 ± 7.8 kglm2, P< 0.05) were greater in endurance athletes than in sedentary control subjects, whereas body mass index was lower (22 ± 1.7 vs 26 ± 3.4 kglm2, P< 0.001). No differences in any of the LVDF characteristics were observed between the groups with the exception of a trend toward a lower atrial filling fraction at rest in the endurance athlete group versus the control subjects (P= 0.07). High‐intensity endurance exercise training promotes exceptional peak exercise oxygen consumption and cardiovascular stamina but does not appear to alter normative aging effects on left ventricular diastolic function. (ECHOCARDIOGRAPHY, Volume 17, January 2000)
Inhalation of Amyl Nitrite and the Measurement of Left Ventricular Outflow Velocity: Studies in Normal, Young Adults
Authors: VANDENBERG BYRON F. , ZINK MARTIN H. , AYRES RICHARD W. , LINDOWER PAUL D. , RATH LINDA S. , LEWIS JANE
Published: December 2007

Amyl nitrite inhalation is useful in the identification of patients with provocable left ventricular (LV) outflow tract obstruction. However, there are no prospective studies that assess the normal change in LV outflow velocity during this intervention. Eighteen normal subjects (mean age, 34 ± 5 years; 9 men and 9 women) inhaled amyl nitrite during measurement of LV outflow velocity. Peak velocity increased from 109 ± 16 cm/s to 144 ± 24 cm/s (P < 0.001). There were no significant gender differences in velocity measurements at baseline or at peak. Our study provides prospective data that may be useful when evaluating young adults for LV outflow tract obstruction with Doppler echocardiography during amyl nitrite inhalation.
Definition of Flow Parameters in Proximal Nonstenotic Coronary Arteries Using Transesophageal Doppler Echocardiography
Authors: KASPRZAK JAROSŁAW D. , DROŻDŻ JAROSŁAW , PERUGA JAN Z. , RAFALSKA KRYSTYNA , KRZEMIŃSKA‐PAKUŁA MARIA
Published: December 2007

Transesophageal echocardiography (TEE) enables the visualization of proximal coronary arteries. We investigated the feasibility of coronary flow evaluation using TEE, as well as to define flow parameters found in normal proximal coronary arteries. The subgroups of patients with normal proximal segments of coronary arteries were selected from the cohort of 210 patients undergoing routine coronary angiography. The left main coronary artery (LMCA), proximal segment of left anterior descending coronary artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) were analyzed separately in 147, 64, 53, and 70 patients, respectively. Proximal coronary arteries were evaluated in the transverse plane using a 5‐MHz TEE probe, and the flow in normal arteries was registered using pulsed‐wave Doppler. The registration of flow with pulsed‐wave Doppler was feasible in 88% of studies for the LMCA, 85% for the LAD, 58% for the LCx, and 65% for the RCA. Normal flow was laminar with distinct phasic character (diastolic predominance). Mean ± SD values of peak coronary flow velocity were (systole/diastole) for the LMCA, 36 ± 11171 ± 19 cm/sec; the LAD, 31 ± 9/67 ± 19 cm/sec; the LCx, 36 ± 13/75 ± 24 cm/sec; and the RCA, 25 ± 8/39 ± 12 cm/sec. Peak diastolic coronary flow velocity was most significantly correlated with heart rate. Doppler evaluation of proximal coronary flow is feasible using TEE in the majority of patients. The knowledge of normal flow values, which is different for the left and the right coronary artery, provides the background for proper interpretation of flow in diseased coronary arteries.
Papillary Fibroelastoma of the Mitral Valve with Systemic Embolization
Authors: KARAEREN HAYRETTIN , ILGENLI T. FIKRET , CELIK TURGAY , DEVECI SALIH , BARCIN CEM , UZUN MEHMET , GENg CELAL , DEMIRTAS ERTAN , KURALAY ERKAN
Published: December 2007

Primary tumors of the heart are rare disorders. In autopsy studies, their incidence was reported to be 0.01–0.5%. We present the case of a papillary fibroelastoma of the mitral valve with systemic embolization in a young man.
Transesophageal Echocardiographic Identification of Left Subclavian Artery Stenosis with Steal Phenomenon
Authors: MUKHTAR OSMAN M. , MILLER ANDREW P. , NANDA NAVIN C. , FUISZ ANTHON R. , PURI VIRENDER K. , AALURI SRINIVASA R. , YESILBURSA DILEK , HUANG WEN YING , ANSINGKAR KAMLESH , ROSS PAULA
Published: December 2007

In this report, we present the first case of the transesophageal echocardiographic identification of left subclavian artery stenosis and steal phenomenon.
Age Dependency of Myocardial Structure: A Quantitative Two‐Dimensional Echocardiography Study in a Normal Population
Authors: MORALES MARIA‐AURORA , FERDEGHINI EZIO‐MARIA , PIACENTI MARCELLO , DATTOLO PIETRO , DISTANTE ALESSANDRO , MAGGIORE QUIRINO
Published: December 2007

Histological changes of the myocardium occur with aging due to an increase in collagen content, hypertrophy of fibers, and patchy fibrosis. Quantitative analysis of conventional echocardiographic images provides an in vivo assessment of myocardial structure by the evaluation of the gray level distribution; with this technique, a relation between myocardial fibrosis and pathological ultrasonic response has been documented. The aim of this study was to evaluate the relation between ultrason‐ically assessed myocardial structure and age in a normal population. Seventy‐eight subjects (47 men; mean age, 51 years; age range, 23–87 years) without apparent cardiovascular and systemic disease underwent conventional two‐dimensional echocardiographic examinations. Still frames at end‐diastole from apical four‐chamber view were digitized and converted in matrices of 256 × 256 pixels. First‐order statistical analysis was performed to describe a region of interest in the interventricular septum. The following parameters were studied: mean (gray level amplitude), standard deviation (overall contrast), uniformity (tonal organization), and entropy (tendency of gray levels to be spread). Myocardial structure was assessed in 75 of 78 subjects, divided into three groups: I, age 23–40 years; II, age 41–65 years; and III, > 65 years. Significant differences for all the parameters were found between the age groups. Age correlated directly with mean and entropy (r = 0.77 and 0.69, respectively) and inversely with uniformity (r = 0.70). Our results suggest that quantitative echocardiography can reveal age‐related changes in myocardial structure that are characterized by a greater echogenicity and loss in tonal organization, possibly due to increased collagen content within the fibers.
Identification of Viable Myocardium by Perfusion Imaging with Intravenous Contrast Echocardiography After Acute Myocardial Infarction
Authors: KUVIN JEFFREY T. , YAO JIEFEN , BLOMBERG PATRICK J. , PANDIAN NATESA G.
Published: December 2007

Myocardial perfusion contrast echocardiography is evolving into an effective method for the evaluation of myocardial blood flow after acute coronary events. The direct injection of ultrasound contrast agents into the aortic and coronary circulation has been shown to accurately identify areas of viable myocardial tissue. Recently, intravenous ultrasound contrast has been found to be useful in detecting microvascular blood flow after the restoration of blood flow in patients with myocardial infarction. We present the case of a patient in whom intravenous ultrasound contrast assisted in the detection of viable myocardial tissue after an acute ischemic syndrome.
Surgical Timing for Mitral Valve Regurgitation
Authors: OFILI ELIZABETH , ODUWOLE ADEFISAYO , LAPA‐BULA RIGOBERT
Published: December 2007

Advances in diagnostic and surgical techniques in the management of mitral regurgitation have resulted in improved survival rates and clinical outcomes. Echocardiography is a valuable noninvasive diagnostic tool in the determination of the timing of surgical correction of mitral regurgitation. Improved surgical techniques, the growing role of mitral valve repair, low operative mortality rates, and improved long‐term survival rates are important considerations for earlier surgical intervention in symptomatic patients and in asymptomatic patients with echocardiographic criteria of left ventricular dilatation. Intraoperative transesophageal echocardiography is very useful in mitral valve repair and valve replacement with preservation of chordal structures.
Timing of Surgery in Chronic Aortic Regurgitation
Authors: KATZ ALAN S. , DEVEREUX RICHARD B.
Published: December 2007

When deciding on therapy for aortic regurgitation (AR), it is imperative to distinguish between acute and chronic AR. Symptoms and echocardiographic findings are essential in distinguishing acute from chronic AR and in assessing the severity. Vasodilators have been shown to be helpful in treating patients with chronic severe AR. The timing of aortic valve replacement in chronic severe AR remains controversial. Symptoms, left ventricular function, and response to exercise have been shown to be the most important prognostic indicators.
Effect of Inotropic Stimulation on Left Atrial Appendage Function in Atrial Myopathy of Chronic Atrial Fibrillation
Authors: KAMALESH MASOOR , COPELAND T. BURTON , SAWADA STEPHEN
Published: December 2007

Atrial fibrillation (AF) leads to remodeling of the left atrium (LA) and left atrial appendage (LAA), resulting in atrial myopathy. Reduced LA and LAA function in chronic AF leads to thrombus formation and spontaneous echo contrast (SEC). The effect of inotropic stimulation on LAA function in patients with chronic AF is unknown. LAA emptying velocity (LAAEV) and maximal LAA area at baseline and after dobutamine were measured by transesophageal echocardiography in 14 subjects in normal sinus rhythm (NSR) and 6 subjects in AF. SEC in the LA was assessed before and after dobutamine. LAAEV increased significantly in both groups. However, the LAAEV at peak dobutamine in patients with AF remained significantly lower than the baseline LAAEV in patients who were in NSR (P= 0.009). Maximal LAA area decreased significantly with dobutamine in both groups, but LAA area at peak dose of dobutamine inpatients with AF remained greater than baseline area in those in NSR (P= 0.01). Despite the increase in LAAEV, SEC improved in only two of five patients. We conclude that during AF, the LAA responds to inotropic stimulation with only a modest improvement in function.
Transesophageal Echocardiography Risk Factors for Stroke in Nonvalvular Atrial Fibrillation
Authors: FAGAN SUSAN M. , CHAN KWAN‐LEUNG
Published: December 2007

Atrial fibrillation is a common arrhythmia, particularly in the older age groups. It confers an increased risk of thromboembolism to these patients, and multiple clinical risk factors have been identified to be useful in predicting the risks of thromboembolic events. Recent studies have evaluated the role of transesophageal echocardiography (TEE) in the evaluation of patients with atrial fibrillation. The purpose of this review is to evaluate the significance of transesophageal echocardiography findings in the prediction of thromboembolic events, particularly stroke, in patients with nonvalvular atrial fibrillation, with an emphasis on recently reported prospective studies. Aortic plaque and left atrial appendage abnormalities are identified as independent predictors of thromboembolic events. Although they are associated with clinical events, they also have independent incremental prognostic values. Other transesophageal echocardiographic findings, such as patent foramen ovale and atrial septal aneurysm, have not been found to be predictors of thromboembolic events in this patient group. Thus, TEE is a useful tool in stratifying patients with nonvalvular atrial fibrillation into different risk groups in terms of thromboembolic events, and it will likely play an important role in future studies to assess new treatment strategies in high‐risk patients with atrial fibrillation.
Spontaneous Echo Contrast: Where There's Smoke There's Fire
Authors: BLACK IAN W.
Published: December 2007

Left atrial (LA) spontaneous echo contrast (SEC), or “smoke,” is a frequent finding on transesophageal echocardiography (TEE), but it is rarely detected with transthoracic echocardiography. LA SEC is characterized by dynamic smoke‐like echoes within the LA cavity or appendage. Most patients with LA SEC have atrial arrhythmias, mitral stenosis, or a mitral valve prosthesis, and they have an enlarged LA, conditions that are associated with LA stasis. Conversely, mitral regurgitation is protective against LA SEC. LA SEC is present in almost all patients with LA thrombus and is associated with previous embolic events in many patient populations. In patients with nonvalvular atrial fibrillation, LA SEC predicts future embolism and death. LA SEC may therefore assist in selecting patients with atrial fibrillation or with mitral stenosis and sinus rhythm who benefit the most from anticoagulation. Hematological studies have shown that LA SEC is a marker of an hypercoagulable state. LA SEC is a manifestation of red cell aggregation, arising from an interaction between red cells and plasma proteins such as fibrinogen, at low shear rates. LA SEC does not require platelets. The detection of LA SEC on ultrasound arises from the increased amplitude of backscatter from red cell aggregates rather than single cells. Patients with LA SEC should be considered for anticoagulant therapy and may require correction of underlying cardiovascular abnormalities. Future directions in LA SEC include further assessment of integrated backscatter for quantification, assessment of its prognostic role in clinically low‐risk patients with nonvalvular AF, and novel pharmacological treatment.
Influence of the Orifice Inlet Angle on the Velocity Profile Across a Flow Convergence Region by Color Doppler In Vitro
Authors: Giesler Martin , Stein Michael , Grossmann Georg , Hombach Vinzenz
Published: December 2007

The converging flow field proximal to a leaking valve is determined among other things by the orifice inlet angle formed by the leaflets. Thus, the inlet angle affects the determination of regurgitant flow rate by the flow convergence method. Based on the hypothesis of spheric isovelocity surfaces, others had postulated that a local velocity within the flow convergence should change inversely proportional to changes in the three‐dimensional inlet angle. This concept would allow correction of the determination of regurgitant flow for nonplanar orifice inlet angles. We tested this concept in vitro. In a flow model, the flow convergence region proximal to different orifice plates was imaged by color Doppler: funnel‐shaped, planar and tip‐shaped (inverted funnels) orifice plates, with circular orifices of 2‐ and 7‐mm diameter. Velocity profiles across the flow convergence along the flow centerline were read from the color maps. As predicted, the local velocities were inversely related to the inlet angle, but only at the 2‐mm funnel orifices, this effect was inversely proportional to the three‐dimensional inlet angle (i.e., in agreement with the mentioned concept). However, for any 7‐mm orifice and/or inlet angle of > 180°, the effect of the inlet angle was considerably less than predicted by the aforementioned concept. With increasing orifice diameter and with decreasing distance to the orifice, the effect of the orifice inlet angle was reduced. The effect of the orifice inlet angle on the flow convergence region is modulated by orifice size and the distance to the orifice. Therefore, correction of flow estimates in proportion to the three‐dimensional inlet angle will lead to considerable errors in most situations of clinical relevance, namely to massive overcorrection when analyzing velocities located close to wide orifices.
Diagnostic and Prognostic Use of Stress Echo in Acute Coronary Syndromes Including Emergency Department Imaging
Authors: Zabalgoitia Miguel , Ismaeil Magdi
Published: December 2007

Early treatment of acute myocardial infarction (AMI) can improve the rate of coronary patency, salvage myocardium, and ultimately save lives; thus, rapid recognition of patients at a higher risk of developing AMI is very important. The clinical history in patients with documented AMI is sometimes atypical, and the initial cardiac enzyme levels often are within the normal range. Moreover, the typical ST‐segment elevation is often absent on the initial electrocardiogram in patients who subsequently sustain an AMI. Stress‐induced segmental wall motion abnormalities (SWMAs) in coronary artery disease patients can be readily detected by conventional two‐dimensional echocardiography. Moreover, echocardiography is the only technique available that allows real‐time assessment of stress‐induced reduction in systolic wall thickening, a highly specific sign of myocardial ischemia. Echocardiography for the diagnosis of acute ischemia is most helpful in subjects with a high clinical suspicion but nondiagnostic electrocardiograms. Under these circumstances, reversible SWMA confirms the diagnosis of acute coronary syndrome. The location of regional SWMAs correlates well with the distribution of the artery involved and pathological evidence of infarction. A trained eye can easily recognize cardiac causes of acute chest pain other than coronary diseases such as aortic stenosis, hypertrophic cardiomyopathy, mitral valve prolapse, pericarditis, and aortic dissection. When echocardiography is performed soon after the patients arrival at the emergency department (ED) or during a chest pain episode, SWMAs are detected in 90–95% of transmural infarctions and in 80–90% of nontransmural or subendocardial infarctions, and the specificity of echocardiography is ˜‐ 80–90% Although stress echocardiography performed in the ED and interpreted at a distance through the use of telemedicine has the potential of being convenient, in our opinion, any form of stress echocardiography should be performed in the echocardiography laboratory only after an AMI has been completely ruled out. The detection of jeopardized myocardium early after AMI can identify patients at a higher risk to develop subsequent events. In conclusion, echocardiography is cost effective in the triage of patients presenting with acute chest pain when performed soon after ED admission or during a chest pain episode. However, echocardiography must be readily available, expeditiously performed, and skillfully interpreted. The clinical use of stress echocardiography in acute coronary syndromes has been greatly improved with the introduction of digital and second harmonics technology and further enhanced by the availability of contrast agents.
Reversible Left Ventricular Dysfunction
Authors: Chaudhry Farooq A. , Singh Binoy , Galatro And Kathleen
Published: December 2007

The extent and degree of myocardial viability are important parameters in the risk stratification of patients with significant left ventricular dysfunction secondary to coronary artery disease. Although several imaging modalities can identify viable myocardium, dobutamine stress echocardiography has gained considerable importance as an accurate, safe, and reliable method. In patients with significant left ventricular dysfunction secondary to coronary artery disease, identification of the presence and extent of contractile reserve and, therefore, viable myocardium during low‐dose dobutamine infusion can predict the recovery of left ventricular function after revascularization, survival rate, and future cardiac events.
Myocardial Contrast Echocardiography: Clinical Benefit and Practical Issues
Authors: Sieswerda Gertjan T.J. , Kamp Otto , Visser Cees A.
Published: December 2007

Real‐time bedside evaluation of myocardial perfusion after intravenous application of micro‐bubbles is the ultimate goal for contrast echocardiography. Over the past decade rapid evolution has occurred in the development of contrast agents, ultrasound equipment tailored to their detection, and image interpretation. This article offers a review of the basic concepts of the technique's background, contrast agent design, and imaging technology. The major clinical indications of myocardial contrast echocardiography are evaluation of acute ischemic syndromes, diagnosis of viable myocardium following AMI, and the detection of CAD using stress contrast perfusion imaging. Furthermore, the article addresses the most significant practical problems and suggested solutions to master those problems. As major new achievements are realistic expectations for the first decade of the twenty‐first century, we conclude that the coupling of a new generation of contrast agents with innovative echocardiographic instrumentation will ultimately enable the full potential of myocardial contrast echocardiography to be realized which may revolutionize modern echocardiography.
The calcium channel α2/δ1 subunit is involved in extracellular signalling
Authors: García Kelly , Nabhani Thomas , García Jesús
Published: December 2007

The α2/δ1 subunit forms part of the dihydropyridine receptor, an essential protein complex for excitation–contraction (EC) coupling in skeletal muscle. Because of the lack of a viable knock‐out animal, little is known regarding the role of the α2/δ1 subunit in EC coupling or in other cell functions. Interestingly, the α2/δ1 appears before the α1 subunit in development and contains extracellular conserved domains known to be important in cell signalling and inter‐protein interactions. These facts raise the possibility that the α2/δ1 subunit performs vital functions not associated with EC coupling. Here, we tested the hypothesis that the α2/δ1 subunit is important for interactions of muscle cells with their environment. Using confocal microscopy, we followed the immunolocalization of α2/δ1 and α1 subunits with age. We found that in 2‐day‐old myotubes, the α2/δ1 subunit concentrated towards the ends of the cells, while the α1 subunit clustered near the centre. As myotubes aged (6–12 days), the α2/δ1 became evenly distributed along the myotubes and co‐localized with α1. When the expression of α2/δ1 was blocked with siRNA, migration, attachment and spreading of myoblasts were impaired while the L‐type calcium current remained unaffected. The results suggest a previously unidentified role of the α2/δ1 subunit in skeletal muscle and support the involvement of this protein in extracellular signalling. This new role of the α2/δ1 subunit may be crucial for muscle development, muscle repair and at times in which myoblast attachment and migration are fundamental.
Effect of Hyperactivity of the Lateral Pterygoid Muscle on the Temporomandibular Joint Disk
Authors: Tanaka Eiji , Hirose Miho , Inubushi Toshihiro , Koolstra Jan Harm , van Eijden Theo M. G. J. , Suekawa Yohei , Fujita Ryuji , Tanaka Masao , Tanne Kazuo
Published: December 2007

In this study, the effect of hyperactivity of the lateral pterygoid muscle (LPM) on the temporomandibular joint (TMJ) disk during prolonged clenching was examined with a mathematical model. Finite element models of the TMJ were constructed based on magnetic resonance images from two subjects with or without internal derangement of the TMJ. For each model, muscle forces were used as a loading condition for stress analysis for 10 min clenching. Furthermore, an intermittent increase of the LPM force with intervals of 1 min was applied. In the asymptomatic model, large stresses were found in the central and lateral part of the disk at the onset of clenching. In the retrodiscal tissue, stress relaxation occurred during the first 2 min of clenching. When the force of the LPM increased temporarily, the disk moved anteriorly and returned to its original position afterward. In the symptomatic model, large stresses were observed in both the posterior region of the disk and the retrodiscal tissue throughout clenching. Upon temporary increase of the LPM force, the disk was elongated anteriorly, which appeared to be irreversible. These results indicate that hyperactivity of the LPM may be involved in the progression of disk displacement.
Finite Element Modeling of the Left Atrium to Facilitate the Design
of an Endoscopic Atrial Retractor
Authors: Jernigan S. R. , Buckner G. D. , Eischen J. W. , Cormier D. R.
Published: December 2007

With the worldwide prevalence of cardiovascular diseases, much attention has been focused on simulating the characteristics of the human heart to better understand and treat cardiac disorders. The purpose of this study is to build a finite element model of the left atrium (LA) that incorporates detailed anatomical features and realistic material characteristics to investigate the interaction of heart tissue and surgical instruments. This model is used to facilitate the design of an endoscopically deployable atrial retractor for use in minimally invasive, robotically assisted mitral valve repair. Magnetic resonance imaging (MRI) scans of a pressurized explanted porcine heart were taken to provide a 3D solid model of the heart geometry, while uniaxial tensile tests of porcine left atrial tissue were conducted to obtain realistic material properties for noncontractile cardiac tissue. A finite element model of the LA was constructed using ANSYS™ Release 9.0 software and the MRI data. The Mooney–Rivlin hyperelastic material model was chosen to characterize the passive left atrial tissue; material constants were derived from tensile test data. Finite element analysis (FEA) models of a CardioVations Port Access™ retractor and a prototype endoscopic retractor were constructed to simulate interaction between each instrument and the LA. These contact simulations were used to compare the quality of retraction between the two instruments and to optimize the design of the prototype retractor. Model accuracy was verified by comparing simulated cardiac wall deflections to those measured by MRI. FEA simulations revealed that peak forces of approximately 2.85N and 2.46N were required to retract the LA using the Port Access™ and prototype retractors, respectively. These forces varied nonlinearly with retractor blade displacement. Dilation of the atrial walls and rigid body motion of the chamber were approximately the same for both retractors. Finite element analysis is shown to be an effective tool for analyzing instrument/tissue interactions and for designing surgical instruments. The benefits of this approach to medical device design are significant when compared to the alternatives: constructing prototypes and evaluating them via animal or clinical trials.
Isometric Finger Device for Assessment and Training of Force Coordination Using Virtual Reality
Authors: Kurillo Gregorij , Mihelj Matjaž , Munih Marko , Bajd Tadej
Published: December 2007

Grasping of stroke patients is often affected by improper coactivation of muscles controlling the fingers. The restoration of hand function therefore represents an important goal in rehabilitation. Quantitative data on coordination between fingers can be helpful for the assessment of therapy effectiveness. We have designed a novel isometric finger device to assess three-dimensional forces applied by the thumb, index, and middle finger. The device was used in connection with a simple virtual reality task where the patient had to open a safe by sequentially rotating a knob using the isometric finger input. The presented virtual reality application was evaluated in a group of healthy subjects and a chronic stroke patient to obtain preliminary performance results. We analyzed the coordination of fingertip forces between the thumb and opposing fingers. Pearson correlation coefficient was determined to assess the coordination of force in each direction. In healthy subjects, the analysis of the fingertip forces showed precise coordination of force between the fingers to control a virtual object. The performance of the stroke patient was considerably lower due to reduced muscle control and presence of strong spasticity. The results showed use of excessive force in both hands and lower coordination of force between the fingers as compared to the healthy subjects. The proposed virtual reality system is considered as a complementary method to the existing methods used in physical and occupational therapy. Specific virtual reality tasks could be designed to train coordination of force between the affected fingers.
Reduced North Atlantic Deep Water Coeval with the Glacial Lake Agassiz Freshwater Outburst
Authors: Kleiven Helga (Kikki) Flesche , Kissel Catherine , Laj Carlo , Ninnemann Ulysses S. , Richter Thomas O. , Cortijo Elsa
Published: December 2007

An outstanding climate anomaly 8200 years before the present (B.P.) in the North Atlantic is commonly postulated to be the result of weakened overturning circulation triggered by a freshwater outburst. New stable isotopic and sedimentological records from a northwest Atlantic sediment core reveal that the most prominent Holocene anomaly in bottom-water chemistry and flow speed in the deep limb of the Atlantic overturning circulation begins at ∼8.38 thousand years B.P., coeval with the catastrophic drainage of Lake Agassiz. The influence of Lower North Atlantic Deep Water was strongly reduced at our site for ∼100 years after the outburst, confirming the ocean's sensitivity to freshwater forcing. The similarities between the timing and duration of the pronounced deep circulation changes and regional climate anomalies support a causal link.
Rare AU-1-Like G3P[9] Human Rotaviruses with a Kun-Like NSP4 Gene Detected in Children with Diarrhea in Italy
Authors: De Grazia S. , Giammanco G. M. , Martella V. , Ramirez S. , Colomba C. , Cascio A. , Arista S.
Published: December 2007

Three G3P[9] rotaviruses, detected in children hospitalized with gastroenteritis in Palermo, Italy, were found to be genetically related to strains of either human or feline origin in the VP7, VP4, and VP6 genes. In contrast, in the NSP4 gene the viruses resembled G2P[4] human strains, suggesting a reassortment between AU-1-like and Kun-like strains.
Abundance and distribution of pelagic 0-group cod (Gadus morhua) in Newfoundland waters: inshore versus offshore
Authors: Anderson J. T. , Dalley E. L. , Carscadden J. E.
Published: December 2007

The Northern cod stock has previously been described as undergoing a large-scale denatant–contranatant migration during which spawning occurs primarily in the north off Labrador. Eggs and larvae are advected southward to the inshore areas along the NE coast of Newfoundland where they settle as juveniles, then there is a gradual return migration to the northern spawning areas. We examined abundance distributions of pelagic juvenile (0-group) cod in the fall between inshore and offshore areas to determine if these fish occurred predominantly inshore following pelagic drift. Comparison between areas demonstrated no differences in abundances and mean sizes. Our results do not support the concept of large-scale advection of eggs and larvae spawned offshore to inshore areas, but indicate that cod eggs spawned offshore remain offshore. Back calculations of spawning times indicate the pelagic juvenile cod sampled offshore were spawned predominantly in April, whereas fish caught inshore were spawned predominantly in May-June, as well as April. Estimates of spawning abundance indicate that the inshore areas along the NE coast of Newfoundland may represent <10% of eggs spawned annually. Historically, the offshore area appears to have been the primary habitat for pelagic juvenile cod.
Invasion of the exotic cladoceran Daphnia lumholtzi into North American reservoirs
Authors: Havel John E. , Mabee William R. , Jones John R.
Published: December 2007

Daphnia lumholtzi, a large cladoceran native to Africa, Asia, and Australia, has recently invaded reservoirs of the southern United States. We examined its distribution, history of invasion, and population dynamics in Missouri reservoirs. Surveys detected the species in 7 of 112 reservoirs in 1992 and 11 of 119 reservoirs in 1993. Analysis of quantitative zooplankton samples from two reservoirs over a 7-year period indicated that D. lumholtzi first reached detectable densities in 1990 and persisted during 1991–1993. Population maxima typically occurred in late summer, with the species absent from the plankton during winter and spring. Based on its current distributional patterns, D. lumholtzi appears to be capable of colonizing most reservoirs in the southern regions of North America.
Mitochondrial DNA and allozyme variation in Atlantic salmon (Salmo salar) populations in Wales
Authors: O'Connell M. , Skibinski D. O. F. , Beardmore J. A.
Published: December 2007

Four restriction enzymes were used to assay mitochondrial DNA (mtDNA) variation in Atlantic salmon (Salmo salar) in Wales. A total of 122 fish from 22 sites, within three catchments, were analyzed. A further 368 fish from seven of these sites were also investigated at 19–21 allozyme loci. The allozyme and mtDNA data revealed significant genetic differentiation between and within catchments. The allozyme data were as informative as mtDNA restriction fragment length polymorphisms in distinguishing between populations of Atlantic salmon. The similarity between data sets in information content is in contrast with previous studies. The relative value of both techniques to fishery managers is discussed.
A class of multicriteria shortest path problems for real-time in-vehicle routing
Authors: Park Dongjoo , Rilett Laurence R , Choi Changho
Published: December 2007

In-route guidance systems fastest path routing has typically been adopted because of its simplicity. However, empirical studies on route choice behavior have shown that drivers use numerous criteria in choosing a route. The objective of this paper is to develop computationally efficient algorithms for identifying a manageable subset of the nondominated (i.e., Pareto optimal) paths for real-time in-vehicle routing. The basic notion of the proposed approach is that (i) enumerating all nondominated paths is computationally too expensive, (ii) obtaining a stable mathematical representation of the driver's utility function is theoretically difficult and impractical, and (iii) identifying the optimal path given a nonlinear utility function is a nondeterministic polynomial time (NP)-hard problem. Consequently, a heuristic two-stage strategy that identifies multiple routes and then selects the near-optimal path may be effective and practical. As the first stage, we relax the uniqueness of the utility function by measuring the context-dependent preference using an entropy model and propose a branch-and-bound technique that discards most of the nondominated paths. To make sure that the paths identified are dissimilar in terms of links used, the portion of shared links between routes is limited. The test of the algorithm in a large real-life traffic network shows that the algorithm can significantly reduce computational complexity while identifying reasonable alternative paths. Key words: real-time vehicle routing, multiple routes, utility function, optimal path.
In situ jet-testing of the erosional resistance of cohesive streambeds
Authors: Shugar Daniel , Kostaschuk Ray , Ashmore Peter , Desloges Joe , Burge Leif
Published: December 2007

Fletchers Creek is located in an urbanizing basin near Toronto and has a bed and banks composed primarily of cohesive Halton Till. Critical shear stress and an erodibility coefficient for the till were determined using an in situ jet-tester that directs a submerged jet of water perpendicular to the sediment surface. The results from 10 jet-tests indicate that the till has a relatively low critical shear stress and relatively high erodibility coefficient and could be susceptible to bed scour during flood events. Many other streams in southern Ontario have urbanizing watersheds with cohesive till beds that may also be susceptible to erosion.Key words: critical stress, submerged jet, erodibility, cohesive soils.
Canadian Standards Association standard A23.3-04 resistance factor for concrete in compression
Authors: Bartlett F M
Published: December 2007

This paper presents the rationale for increasing the resistance factor for concrete in compression in the 2004 edition of the Canadian Standards Association (CSA) standard A23.3, Design of concrete structures, from 0.60 to 0.65 and for precast concrete produced in CSA-certified plants from 0.65 to 0.70. The new values are supported by a probability-based resistance factor calibration and an investigation of their impact in the context of current American standards and past editions of A23.3. The work was initiated because parameters for the rectangular concrete stress block introduced in the 1994 edition of A23.3 give smaller factored resistances for concretes with strengths between 20 and 40 MPa. Minimum target reliability indices for components that fail suddenly are maintained using the new resistance factors. In the regions of compressive force – bending moment interaction diagrams that are controlled by the resistance factor for concrete, the factored resistances computed using the 2004 edition of A23.3 are similar to those of current American design criteria.Key words: code calibration, compression-initiated failure, concrete, interaction diagram, rectangular stress block, ultimate limit state.
Hydrodynamic loadings on a floating guard wall at a navigation lock
Authors: Alarcon Cristhian A. Mancilla , McAnally William H , Stockstill Richard L
Published: December 2007

New float-in technology is being applied to construction of floating guard walls in navigation projects such as Olmsted lock and dam on the Ohio River. Guard wall fluid-structure interaction design can be decoupled if the effects of the structural response on the fluid load pattern are negligible. The assumption that the hydrodynamic pressures acting on a floating guard wall can be decoupled from the structural response of the wall is tested. The effects of the flow and pressure distribution in the presence of a typical guard wall were modeled and used as boundary conditions for structural analysis of the guard wall. The deformation of the guard wall was then used to recompute the fluid loads. Because the fluid loading did not change significantly, decoupling is considered to be valid.Key words: hydrodynamic forces, lock guard walls, navigation locks, numerical modeling.