bluuebunny/crossref_metadata_2025 huggingface dataset:
Supply Management Under High Goal Incongruence: An Empirical Examination of Disintermediation in the Aerospace Supply Chain
Authors: Rossetti Christian L. , Choi Thomas Y.
Published: July 2008

Aftermarket sales and profits are becoming an increasingly important part of an original equipment manufacturer's (OEM) business model. Because replacement parts often do not require further manufacturing, OEMs act as intermediaries in the aftermarket. As with any intermediary, the OEM must concern itself with suppliers disintermediating its supply chain selling replacement parts directly to the OEM's customers. We frame supply chain disintermediation (SCD) as a principal–agent contracting problem between an OEM buyer and a supplier. Hypotheses relate contract conditions, goal incongruence, supplier capabilities and contract enforcement to SCD. The data are collected from the aerospace industry using a multimethod study, combining an Internet‐based survey with archival data. Causal modeling with structural equation modeling (SEM) shows general support for the hypotheses. Particularly, SCD is positively related to buyer–supplier goal incongruence. The agency model offers insights that differ from previous transaction‐cost‐based models of buyer–supplier relationships. OEM buyers with a lucrative aftermarket should consider aligning goals through incentives rather than relying entirely on economic hostages associated with specific assets.
Global Multisourcing Strategy: The Emergence of a Supplier Portfolio in Services Offshoring
Authors: Levina Natalia , Su Ning
Published: July 2008

In today's global services outsourcing arena, increasing numbers of companies adopt “multisourcing,” that is, they select and combine information technology (IT) and business services from multiple providers. The literature on IT outsourcing and supply chain management has identified critical tradeoffs involved in increasing the number of suppliers and has strongly recommended focusing on a handful of strategic partners to balance these tradeoffs. Committing to a few strategic partners, however, may prevent a firm from discovering new suppliers, or even supply regions. Such missed opportunities may be particularly limiting in the context of offshoring professional services, which has exhibited rapid changes in supplier markets in the last decade. Thus, firms may want to engage in a more intensive multisourcing in services. If they do so, their success will depend on a global sourcing process that effectively addresses the critical tradeoffs involved. To explore how a global sourcing process can support multisourcing, we conducted a qualitative longitudinal case study of a large financial services institution that developed a varied global supply base to obtain offshore professional services. Our analysis results in a theory that emphasizes (i) advantages of a multiple provider strategy in rapidly changing global supply markets; (ii) the critical role of middle managers in enabling continuous innovation in the supplier structure; and (iii) the importance of the global sourcing process combining top–down and bottom–up decision making in multisourcing.
Toward a Typology of Buyer–Supplier Relationships: A Study of the Computer Industry*
Authors: Tangpong Chanchai , Michalisin Michael D. , Melcher Arlyn J.
Published: July 2008

Buyer–supplier relationship typologies are useful analytical tools for purchasing managers in managing exchange relationships with suppliers and monitoring their purchasing portfolios. Existing buyer–supplier relationship typologies are mainly focused on either relational contents or power‐dependence and have limited empirical support for their performance implications. In this study, we developed an alternative buyer–supplier relationship typology that integrates both relational content and power‐dependence dimensions, resulting in four generic relationship types: market, power, autonomous‐link, and constrained‐link relationships. We then performed a longitudinal exploratory investigation of eight leading firms in the U.S. computer industry to explore the performance implications of the typology, using a combinatorial qualitative approach that leverages the strengths of case study research, content analysis, and quasi‐experimental design. The results suggest three theoretical propositions. First, the association between the type of buyer–supplier relationships and buyer firm performance varies such that constrained‐link relationships are superior in terms of operational efficiency while autonomous‐link relationships are superior in terms of product innovation. Second, the positive association between buyer–supplier relational contents (i.e., relationalism) and buyer firm operational efficiency is strengthened as the suppliers' dependence on the buyer firm increases. And finally, the positive association between buyer–supplier relationalism and buyer firm product innovation is weakened as the suppliers' dependence on the buyer firm increases.
Effects of Continuous and Triggered Atrial Overdrive Pacing on Paroxysmal Atrial Fibrillation in Pacemaker Patients
Authors: SCHUCHERT ANDREAS , REBESKI HANS‐PETER , PEIFFER THOMAS , BUB EBERHARD , DIETZ ARMIN , MORTENSEN KAI , ALI AYDIN MOHAMMED , CAMM JOHN , GAZAREK STEFFEN , MEINERTZ THOMAS ,   on behalf of the 3:4 Study Group
Published: July 2008

Background: The aim of the study was to compare the effects of different pacing strategies to prevent paroxysmal atrial fibrillation (AF): triggered atrial overdrive pacing versus the combination of triggered and continuous overdrive pacing.

Methods

: Patients with an indication for dual‐chamber pacing (Selection 9000, Prevent AF; Vitatron B.V., Arnhem, the Netherlands) and a history of paroxysmal AF were randomized to triggered atrial pacing (three pacing functions, “triggered group”: PAC Suppression™, Post‐PAC Response™, and Post‐Exercise Response™) or to the combination of continuous (Pace Conditioning™) and triggered atrial pacing (four pacing functions, “combined group”). After 3 months, there was a crossover to the other pacemaker setting.

Results

: In 171 enrolled patients, the median AF burden of the combined group was with 2.1% versus 0.1% in the triggered group (P = 0.014). Fewer AF episodes were observed in the triggered (median: 7) than in the combined group (median: 116; P = 0.016). The combined group had more frequent atrial pacing (median 97%) than the triggered group with 85% (P < 0.001), but ventricular pacing was not significantly different with 95% and 96% in the combined and triggered group, respectively. After the crossover, the AF burden increased in the triggered group to 0.3% and decreased in the combined group to 0.4%.

Conclusions

: Triggered atrial pacing functions alone resulted in a low AF burden. The additional activation of continuous atrial overdrive pacing increased the percentage of atrial pacing, but had no beneficial effects on the prevention of paroxysmal AF.
Characterization of Transient Atrial Rhythm Occurring between Typical Atrial Flutter and Its Termination with Class III Drugs
Authors: MORITA NORISHIGE , KOBAYASHI YOSHINORI , IWASAKI YU‐KI , HAYASHI MEISO , MIYAUCHI YASUSHI , ATARASHI HIROTSUGU , TANAKA KEIJI , KATOH TAKAO , MIZUNO KYOICHI
Published: July 2008

Background: The transient atrial rhythm intervened between atrial flutter (AFL) and its termination during class III antiarrhythmic drug therapy for AFL has not been characterized well.

Methods: Eighteen patients with typical AFL were included in this study. The transient atrial rhythms converted from AFL with different class III antiarrhythmic drugs, ibutilide (group 1, N = 8) and nifekalant (group 2, N = 10), were determined.

Results: AFL terminated, without any intervened transient atrial rhythms, due to conduction block within the isthmus in three patients in each group. The transient atrial rhythm could be characterized into the following types of rhythm based on the initiating mechanisms. (1) The lower‐loop reentry or atrial fibrillation that was triggered by a premature excitation in the lateral right atrium caused by breakdown of a functional barrier predisposed AFL to the termination in three patients in each group. (2) The return excitation that repetitively emerged within the isthmus collided with the antegrade excitation, resulting in the termination in two group 1 patients and in one group 2 patient. In the patients who developed these atrial rhythms, the cycle length (CL) oscillation coincidently increased with emergence of such rhythms and became significantly greater than that in the patients who did not develop such transient rhythms (P < 0.05).

Conclusions: The transient atrial rhythms that emerged with class III drugs are associated with the disruption of the stable AFL reentry that may be triggered by similar electrophysiologic mechanisms with different class III drugs. The increased flutter CL oscillation developing after such drugs might signal the AFL termination.
Sinus Rhythm Restoration after Atrial Fibrillation: The Clinical Value of N‐Terminal Pro‐BNP Measurements
Authors: DANICEK VLADIMIR , THEODOROVICH NICK , BAR‐CHAIM SHMUEL , MILLER ASAF , VERED ZVI , KOREN‐MORAG NIRA , URIEL NIR , CZURIGA ISTVAN , SHOPEN ANDREY , BRANTRISS NURIT , KALUSKI EDO
Published: July 2008

Aim: To examine the effects of sinus rhythm (SR) restoration on N‐Terminal pro‐BNP (NTP‐BNP) in patients with atrial fibrillation (AF).

Methods: Subjects with paroxysmal and persistent AF and absence of organic heart disease were prospectively studied. Chemical or electrical restoration of SR was attempted within 48 hours (n = 37) or >3 weeks (n = 73). Clinical and laboratory (NTP‐BNP, 72‐hour Holter monitor, and electrocardiogram) assessment were obtained at baseline and at 1, 30, and 180 days after SR restoration. Patients were divided into three predefined “outcome groups”: (a) maintenance of SR for 1 month, (b) SR with recurrent paroxysmal AF (PaAF), and (c) early (<30 days) recurrence persistent AF (RAF).

Results: Of the 110 patients enrolled, 89 had initial successful SR restoration. Baseline NTP‐BNP was 936 pg/mL (interquartile range (IQR) 333–2,026); ratio between baseline and 30‐day NTP‐BNP was 10.2 (IQR 6.42–22.0) for SR group, 3.3 (IQR 2.45–7.34) for PaAF, and 1.07 (IQR 0.87–1.22) for RAF (P < 0.001). Patients with ratio ≤3 were more likely to have PaAF (46% vs 3%, OR 30, P < 0.001).

Conclusion: With SR restoration, NTP‐BNP decline is observed up to 1 month. NTP‐BNP drop is partially or completely abolished by PaAF and RAF, respectively. NTP‐BNP does not predict successful SR restoration.
Integration of Automatic Intrathoracic Fluid Content Measurement into Clinical Decision Making in Patients with Congestive Heart Failure
Authors: KNACKSTEDT CHRISTIAN , MISCHKE KARL , SCHIMPF THOMAS , WARINGER JILL , FACHE KERSTIN , FRECHEN DIRK , GRAMLEY FELIX , KELM MALTE , SCHAUERTE PATRICK
Published: July 2008

Background: Hospitalizations due to decompensation are a frequent problem in treating patients with congestive heart failure (CHF). Continuous impedance measurement via implantable devices may detect pulmonary fluid accumulation due to worsening CHF. An acoustic alert might allow an earlier treatment of impending decompensation. An algorithm that implemented impedance measurement into clinical decision making in treating CHF patients was evaluated.

Methods: Forty‐two CHF patients (ejection fraction: 27 ± 6%; New York Heart Association 2.9 ± 0.6) with cardiac resynchronization therapy and automatic impedance measurements were included. Upon an alert, a stepped therapy was initiated: category (1) overt decompensation, hospitalization; category (2) worsened CHF, increase of diuretics; category (3) no CHF worsening, brain natriuretic peptide (BNP) measurement, elevated BNP: increase of diuretics, normal BNP: no specific treatment.

Results: During 18 ± 4 months, 45 alerts were treated according to the algorithm. Eleven category 1 alerts led to hospitalization; 21 category 2 and 11 category 3 patients (elevated BNP) were treated conservatively. Two category 3 alerts (normal BNP) received no treatment.

Conclusions: Automatic impedance measurement can be integrated into CHF management. BNP measurement restricted to patients with alert but without clinical signs of worsened CHF may prevent premature therapy escalation.
Markers of Coronary Sinus Accessory Pathways in Pediatrics
Authors: AVARI JENNIFER N. , RHEE EDWARD K.
Published: July 2008

Introduction: Coronary sinus accessory pathways (CSAPs), atrioventricular connections formed by the coronary sinus myocardial coat, have been described in adult patients, but not systematically described in pediatric patients.

Methods: Patients who underwent CSAP ablation were compared to patients with right posteroseptal (RPS) pathway ablation (control group) from November 2004 to June 2007. Retrospective reviews of preablation 12‐lead electrocardiogram (EKG), fluoroscopic, and intracardiac electrogram data were then performed to identify electrophysiologic markers of CSAP.

Results: A total of 23 patients were identified: 13 with CSAP and 10 with RPS pathways. Preablation EKGs demonstrated preexcitation in 8/10 (80%) patients with RPS pathways versus 9/13 (69%) patients with CSAP (P = 0.66). Preexcitation with a negative delta wave in lead II was seen in 5/9 (56%) patients with CSAP versus 0/8 in RPS (P = 0.029), and preexcitation with a positive delta wave in augmented vector right (aVR) was seen in 9/9 (100%) patients with CSAP versus 3/8 (37.5%) with RPS (P = 0.009). Accessory pathway (AP) potentials were seen on the coronary sinus (CS) catheter in 6/13 (46%) of CSAP and in 0 RPS ablations (P = 0.019). Recurrence of tachycardia occurred in 5/13 (38%) of patients with CSAP and 1/10 (10%) of patients with RPS pathways (P = 0.18).

Conclusions: CSAPs should be considered when preablation EKG demonstrates preexcitation with a negative delta wave in lead II and a positive delta wave in aVR, and if an AP potential is seen on the CS catheter. Recurrence of tachycardia postablation or the need for multiple ablations should raise suspicion for a CSAP.
Lack of Diurnal Variation of P‐Wave and QT Dispersions in Patients with Heart Failure
Authors: GUNES YILMAZ , TUNCER MUSTAFA , GUNTEKIN UNAL , AKDAG SERKAN , GUMRUKCUOGLU HASAN A.
Published: July 2008

Background:

P‐wave dispersion (PWD) is a new parameter for the assessment of risk of atrial fibrillation and has been reported to be increased in heart failure. Diurnal variation of the PWD has been reported in patients with coronary artery disease (CAD). QT dispersion (QTD) has also a circadian variation. In this study we aimed to search diurnal variation of PWD and QTD in patients with heart failure.

Methods:

Fifty‐three clinical heart failure patients having left ventricular ejection fraction (LVEF) <40% were divided into two groups according to presence of CAD. Twelve‐lead ECGs were obtained in the morning (07:00–08:00 hours), at noon (12:00–14:00 hours), and at night (22:00–24:00 hours).

Results:

All the patients were in New York Heart Association class II except one in class I. β‐blocker and angiotensin‐converting enzyme inhibitor or angiotensin receptor blocker usage was over 80% and spiranolactone usage was around 75% in the study group. PWD and QTD were not significantly different between patients with (n = 27) and without (n = 26) CAD. There was no significant diurnal variation of P wave and QT parameters.

Conclusions:

We found that PWD and QTD do not show diurnal variation in patients having either ischemic or nonischemic origin of heart failure treated with optimal drug therapy.
Termination of Long‐Lasting Persistent Versus Short‐Lasting Persistent and Paroxysmal Atrial Fibrillation by Ablation
Authors: FIALA MARTIN , CHOVANČÍK JAN , NEVŘALOVÁ RENÁTA , NEUWIRTH RADEK , JIRAVSKÝ OTAKAR , JANUŠKA JAROSLAV , BRANNY MARIAN
Published: July 2008

Background: Left atrial (LA) structures for the maintenance of different atrial fibrillation (AF) forms are not uniform. The incidence, electrophysiological patterns, and LA sites of sinus rhythm (SR) restoration during ablation of different AF forms were evaluated.

Methods: One hundred patients with long‐lasting persistent AF were retrospectively compared to 35 patients with short‐lasting persistent AF and 59 patients with a sustained episode of paroxysmal AF. All patients underwent a first ablation using a stepwise ablation approach with the endpoint of SR restoration by ablation.

Results: SR was restored in 38%, 83%, and 97% of patients with long‐lasting persistent, short‐lasting persistent, and paroxysmal AF, respectively (P <0.001 for long‐lasting persistent vs paroxysmal AF; P = 0.02 for long‐lasting persistent vs short‐lasting persistent AF). When modes and sites of SR restoration were evaluated among the patients with long‐lasting persistent, short‐lasting persistent, and paroxysmal AF, SR was restored via conversion into LA tachycardia in 79%, 52%, and 4% of patients (P <0.001 for long‐lasting persistent vs paroxysmal AF); by the pulmonary vein encircling in 8%, 24%, and 93% patients (P <0.001 for long‐lasting persistent vs paroxysmal AF); and by ablation at the LA anterior wall or inside the coronary sinus in 66%, 45%, and 2% patients (P <0.001 for long‐lasting persistent and paroxysmal AF). During the 31 ± 14 month follow‐up since the first ablation, of the 50 patients with long‐term SR maintenance (38 patients free of class I or III antiarrhythmic drugs), SR was restored by ablation in 29 (58%) patients versus nine (18%) patients out of 50 patients with unsuccessful clinical outcome (P = 0.009).

Conclusion: Ablation of long‐lasting persistent AF was characterized by more frequent failure to restore SR, and predominant conversion into LA tachycardia prior to SR restoration, and SR restoration by ablation outside the LA posterior wall. SR restoration by ablation was associated with better clinical outcome in these patients.
Effects of Corticosteroid Therapy on the Long‐Term Outcome of Radiofrequency Lesions in the Swine Caval Veins
Authors: FENELON GUILHERME , NASCIMENTO THAIS , DE ARAÚJO SÉRGIO , OKADA MIEKO , FRANCO MARCELLO , DE PAOLA ANGELO A. V.
Published: July 2008

Background: We explored the angiographic and pathological effects of corticosteroids on the long‐term outcome of radiofrequency (RF) ablation lesions in the swine caval veins.

Methods: Under fluoroscopy guidance, a single linear RF lesion (4‐mm tip, 60°C, 180 seconds) was created in each vena cava (from ±2 cm into the vein to the venoatrial junction) of 20 anesthetized minipigs (35± 2 kg). Three groups were studied: acute (n = 4), killed 1 hour after RF; control (n = 8), sacrificed 83± 1 days after RF; and pigs (n = 8) receiving hydrocortisone (400 mg i.v. after RF) and prednisone (25 mg po for 30 days), killed 83± 1 days post‐RF. Angiography was performed before, immediately after ablation, and at follow‐up. Then, animals were sacrificed for histological analysis.

Results: Mild (<40%) or moderate (41–70%) acute luminal narrowing occurred in 19/20 (95%) inferior veins and in 13/20 (65%) superior veins. Severe (>70%) stenosis and occlusions were not noted. At follow‐up, in both chronic groups, mean vessel diameters returned to baseline and progression of luminal narrowing did not occur in any vein. Of note, superior and inferior vena cava angiographic diameter for control and treated pigs did not differ. The same was observed for the cross‐sectional luminal area. Acute lesions displayed transmural coagulative necrosis whereas chronic lesions revealed marked fibrosis. Histological findings were similar in controls and treated pigs.

Conclusion: In this model, mild and moderate stenosis, occurring immediately after ablation, seems to resolve over time. Corticosteroids do not affect the long‐term outcome of such RF lesions in the caval veins.
A Pilot Study of a Low‐Tilt Biphasic Waveform for Transvenous Cardioversion of Atrial Fibrillation: Improved Efficacy Compared with Conventional Capacitor‐Based Waveforms in Patients
Authors: GLOVER BENEDICT M. , McCANN CONOR J. , MANOHARAN GANESH , WALSH SIMON J. , MOORE MICHAEL J. , ALLEN JAMES D. , ESCALONA OMAR , ANDERSON JOHN MCC. , TROUTON TOM G. , STEVENSON MIKE , ROBERTS MICHAEL J. , ADGEY JENNIFER AA.
Published: July 2008

Background:

The optimal waveform tilt for defibrillation is not known. Most modern defibrillators used for the cardioversion of atrial fibrillation (AF) employ high‐tilt, capacitor‐based biphasic waveforms.

Methods:

We have developed a low‐tilt biphasic waveform for defibrillation. This low‐tilt waveform was compared with a conventional waveform of equivalent duration and voltage in patients with AF. Patients with persistent AF or AF induced during a routine electrophysiology study (EPS) were randomized to receive either the low‐tilt waveform or a conventional waveform. Defibrillation electrodes were positioned in the right atrial appendage and distal coronary sinus. Phase 1 peak voltage was increased in a stepwise progression from 50 V to 300V. Shock success was defined as return of sinus rhythm for ≥30 seconds.

Results:

The low‐tilt waveform produced successful termination of persistent AF at a mean voltage of 223 V (8.2 J) versus 270 V (6.7 J) with the conventional waveform (P = 0.002 for voltage, P = ns for energy). In patients with induced AF the mean voltage for the low‐tilt waveform was 91V (1.6 J) and for the conventional waveform was 158 V (2.0 J) (P = 0.005 for voltage, P = ns for energy). The waveform was much more successful at very low voltages (less than or equal to 100 V) compared with the conventional waveform (Novel: 82% vs Conventional 22%, P = 0.008).

Conclusion:

The low‐tilt biphasic waveform was more successful for the internal cardioversion of both persistent and induced AF in patients (in terms of leading edge voltage).
Asymmetric Dimethylarginine Concentration and Early Recurrence of Atrial Fibrillation after Electrical Cardioversion
Authors: XIA WEI , QU XIUFEN , YU YANG , ZHANG XUELI , FENG WEI , SONG YING
Published: July 2008

Background:

The purpose of this study was to determine whether high asymmetric dimethylarginine (ADMA) levels could predict early recurrence of atrial fibrillation (AF) after successful electrical cardioversion (CV).

Methods

: Seventy patients with persistent AF, but without known heart disease, who underwent elective electrical CV were enrolled. Blood samples for ADMA determination were drawn from all patients just before the CV.

Results

: The study population comprised 64 patients (men 73%, age 62.56 ± 7.72 years, duration of AF 6.00 ± 1.90 months) in whom sinus rhythm was restored. After 1‐month follow‐up, 30 (47%) patients had recurrence of AF. The median ADMA concentration was significantly higher in patients with AF recurrence (1.93 μmol/L vs 1.43 μmol/L; P = 0.001). AF recurrence was associated with higher pre‐CV ADMA levels (odds ratio [OR]= 4.20; 95% confidence interval [CI], 1.44–12.22; P = 0.001). On multivariate analysis, ADMA was the only independent predictor of arrhythmia recurrence (OR = 4.19; 95%CI, 1.12–15.77; P = 0.034).

Conclusion

: Our data suggest that high levels of ADMA are associated with an increased risk of AF recurrence within 1 month after electrical CV, supporting the hypothesis that ADMA might participate in the process of atrial remodeling.
Resynchronization: What if the Left Ventricular Lead Cannot Reach the Lateral or Posterolateral Wall?
Authors: D'IVERNOIS CHRISTOPHE , LESAGE JÉRÔME , BLANC PATRICK
Published: July 2008

Background:

The recommended left ventricular (LV) lead position for cardiac resynchronization therapy (CRT) is at the lateral or posterolateral wall. However, LV leads cannot always be implanted at this site. The objective of our study was to compare the clinical response to CRT when the LV lead could be implanted or not at the lateral or posterolateral wall.

Methods:

In consecutive patients implanted with a CRT device, we documented the final position achieved by the tip of the LV lead in the left anterior oblique projection. Patients were prospectively followed for 6 months after implantation. They were defined as responders if they were alive, had gained 1 New York Heart Association (NYHA) functional class, and had not been hospitalized for heart failure.

Results:

The study population consisted of 77 patients (56 men, 71 ± 10 years, 62 NYHA class III, 15 NYHA class IV). The LV lead was implanted at the lateral or posterolateral wall in 54 patients (group A) and at the anterior or anterolateral wall in 23 patients (group B). At 6 months, seven patients (9%) died (all in group A). There were 37 responders (69%) in group A as compared to 22 (96%) in group B.

Conclusions:

The responder rate was not inferior when the LV lead was implanted at the anterior or anterolateral wall. Thus, in case of failed implantation at the lateral or posterolateral wall, positioning the LV lead in a more anterior location appears to be a reasonable alternative. Further studies are required to confirm these findings.
Electrocardiographic Features in a Patient with the Coexistence of Long QT Syndrome and Coronary Vasospasm
Authors: TANAKA YASUAKI , NISHIZAKI MITSUHIRO , YAMAWAKE NORIYOSHI , SAKURADA HARUMIZU , HIRAOKA MASAYASU
Published: July 2008

A 20‐year‐old woman suffered from cardiopulmonary arrest due to ventricular fibrillation. The electrocardiogram after resuscitation showed prolonged QTc interval with bifid T wave. On the third hospital day, the QTc interval and the T‐wave changes improved. However, the QTc interval was distinctively prolonged after administration of epinephrine, oral glucose load, and intracoronary acetylcholine (Ach) into the left coronary artery. Moreover, an injection of Ach into the right coronary artery provoked severe coronary spasm. This is a case of the coexistence of long QT syndrome (LQTS) and coronary vasospasm, which may give an important clinical implication for the treatment of LQTS.
Cardiac Conduction Disturbances and Ventricular Tachycardia after Prolonged Propofol Infusion in an Infant
Authors: ROBINSON JOSHUA D.C. , MELMAN YONATHAN , WALSH EDWARD P.
Published: July 2008

We report an infant who, after prolonged intravenous propofol infusion for treatment of status epilepticus, developed dramatic cardiac conduction disturbances and tachyarrhythmias in the setting of only mild metabolic acidosis and good ventricular function. Certain electrocardiographic findings were similar to those observed in the Brugada syndrome as well as in adult patients with propofol toxicity who suffered fatal ventricular arrhythmias. This case illustrates that serious arrhythmias can occur during prolonged high‐dose propofol infusion in young patients, probably through a direct electrophysiologic membrane effect.
Cardiac Resynchronization Therapy in a Patient with a Mitral Annuloplasty Device
Authors: MUELLER DIRK , TSCHOEPE CARSTEN , SPENCKER SEBASTIAN
Published: July 2008

We present a case of a 58‐year‐old man. Due to high‐degree mitral regurgitation an anuloplasty device (MONARC™) was inserted. During continuous pacing, inter‐ and intraventricular asynchrony occurred and heart failure worsened. The indication for cardiac resynchronization was established. A biventricular ICD was successfully inserted with the left ventricular approach via the coronary sinus over the MONARC™ device (Edward Lifescience, Irvine, CA, USA).
Biventricular pacing significantly shortened the QRS duration and improved the clinical status as well as the 6‐minute walking test.
Venoplasty of Innominate Bridge during Implantation of Single‐Chamber ICD in a Patient with a Persistent Left‐Sided Superior Vena Cava
Authors: TAURAS JAMES M. , PALMA EUGEN C.
Published: July 2008

The persistent left‐sided superior vena cava (PLSVC) is a common congenital abnormality, occurring in approximately 1% of patients. The presence of a PLSVC can complicate the implantation of a pacemaker or an automatic implantable cardioverter‐defibrillator (AICD). In this case, we report a procedure, venoplasty of an innominate branch, to facilitate implantation of a right ventricular lead in a single‐chamber AICD. This approach could potentially reduce procedure and fluoroscopy time in other similar cases.
Ropinirole‐Induced Symptomatic Sinus Node Dysfunction
Authors: SZYMANSKI CATHERINE , BOEY SERGE , HERMIDA JEAN S.
Published: July 2008

Restless legs syndrome is a neurological disorder that can be treated with ropinirole. We report the case of a patient who presented with syncope during treatment with ropinirole due to prolonged sinus pauses. The treatment was discontinued and the patient remained asymptomatic. Ropinirole may induce symptomatic sinus pauses in patients without organic sinus node dysfunction.
Asystole Caused by Vegetation and Abscess of Right Ventricle Attached to a Tip of Pacemaker Lead
Authors: YAMAOKA MASAYA , NODA TAKASHI , NAGASAWA HIKARU , NAGANUMA MASAKI , OTSUBO RYOICHI , OKAMURA HIDEO , ISHIBASHI‐UEDA HATSUE , KAMAKURA SHIRO
Published: July 2008

A 69‐year‐old man with pacemaker was referred to our center for cerebral infarction. He had a high fever for 10 days during his hospitalization. Pacing failures deteriorating to asystole were observed responsible for bacterial vegetation around the tip of the pacemaker lead, which is rare but important for the cause of pacing failure.
Ranolazine Shortens Repolarization in Patients with Sustained Inward Sodium Current Due to Type‐3 Long‐QT Syndrome
Authors: MOSS ARTHUR J. , ZAREBA WOJCIECH , SCHWARZ KARL Q. , ROSERO SPENCER , MCNITT SCOTT , ROBINSON JENNIFER L.
Published: July 2008

Introduction: One form of the hereditary long‐QT syndrome, LQT3‐ΔKPQ, is associated with sustained inward sodium current during membrane depolarization. Ranolazine reduces late sodium channel current, and we hypothesized that ranolazine would have beneficial effects on electrical and mechanical cardiac function in LQT3 patients with the SCN5A‐ΔKPQ mutation.

Methods: We assessed the effects of 8‐hour intravenous ranolazine infusions (45 mg/h for 3 hours followed by 90 mg/h for 5 hours) on ventricular repolarization and myocardial relaxation in 5 LQT3 patients with the SCN5A‐ΔKPQ mutation. Changes in electrocardiographic repolarization parameters from before to during ranolazine infusion were evaluated by time‐matched, paired t‐test analyses. Cardiac ultrasound recordings were obtained before ranolazine infusion and just before completion of the 8‐hour ranolazine infusion.

Results: Ranolazine shortened QTc by 26 ± 3 ms (P < 0.0001) in a concentration‐dependent manner. At peak ranolazine infusion, there was a significant 13% shortening in left ventricular isovolumic relaxation time, a significant 25% increase in mitral E‐wave velocity, and a meaningful 22% decrease in mitral E‐wave deceleration time compared with the baseline. No adverse effects of ranolazine were observed in the study patients.

Conclusion: Ranolazine at therapeutic concentrations shortened a prolonged QTc interval and improved diastolic relaxation in patients with the LQT3‐ΔKPQ mutation, a genetic disorder that is known to cause an increase in late sodium current.
High‐Density Mapping of Atrial Fibrillation in Humans: Relationship Between High‐Frequency Activation and Electrogram Fractionation
Authors: STILES MARTIN K. , BROOKS ANTHONY G. , KUKLIK PAWEL , JOHN BOBBY , DIMITRI HANY , LAU DENNIS H. , WILSON LAUREN , DHAR SHASHI , ROBERTS‐THOMSON ROSS L. , MACKENZIE LORRAINE , YOUNG GLENN D. , SANDERS PRASHANTHAN
Published: July 2008

Introduction: Sites of complex fractionated atrial electrograms (CFAE) and dominant frequency (DF) have been implicated in maintaining atrial fibrillation (AF); however, their relationship is poorly understood.

Methods and Results: Twenty patients underwent biatrial high‐density contact mapping (507 ± 150 points/patient) during AF. CFAE were characterized using software to quantify electrogram complexity (CFE‐mean). Spectral analysis determined the frequency with greatest power and sites of high DF with a frequency gradient. CFE‐mean was higher (less fractionated) for right compared with left atria (P < 0.001) and in paroxysmal compared with persistent AF (P < 0.001). DF was lower for right compared with left atria (P = 0.02) and in paroxysmal compared with persistent AF (P < 0.001). There was significant regional variation in DF in paroxysmal (P < 0.001) but not persistent AF. Highest DF points clustered together with 5.2 ± 1.7 clusters/patient. Correlation between CFE‐mean and DF was poor on a point‐by‐point basis (r =−0.17, P < 0.001), but moderate on an individual basis (r =−0.50, P = 0.03). Exploration of their spatial relationship demonstrated CFAE areas in close proximity (median 5 mm, IQR 2–10) to high DF sites; within 10 mm in 80% and 10–20 mm in 10%. Simultaneous activation mapping at these sites further supports this observation.

Conclusion: Greater fractionation and higher DF are seen in persistent AF and left atria during AF. Preferential areas of high DF are observed in paroxysmal but not persistent AF. CFAE and DF correlate within an individual but not point‐by‐point. Exploration of their spatial relationship demonstrates CFAE in areas adjacent to high DF, and this is supported by activation mapping at these sites.
Magnetic Navigation and Catheter Ablation of Right Atrial Ectopic Tachycardia in the Presence of a Hemi‐Azygos Continuation: A Magnetic Navigation Case Using 3D Electroanatomical Mapping
Authors: ERNST SABINE , CHUN JULIAN K.R. , KOEKTUERK BUELENT , KUCK KARL‐HEINZ
Published: July 2008

Introduction: We report on a 63‐year‐old female patient in whom an electrophysiologic study discovered a hemi‐azygos continuation. Using the magnetic navigation system, remote‐controlled ablation was performed in conjunction with the 3D electroanatomical mapping system.

Methods and Results: Failing the attempt to advance a diagnostic catheter from the femoral vein, a diagnostic catheter was advanced via the left subclavian vein into the coronary sinus. The soft magnetic catheter was positioned in the right atrium via the hemi‐azygos vein, and 3D mapping demonstrated an ectopic atrial tachycardia. Successful ablation was performed entirely remote controlled. Fluoroscopy time was only 7.1 minutes, of which 45 seconds were required during remote navigation.

Conclusion: Remote‐controlled catheter ablation using magnetic navigation in conjunction with the electroanatomical mapping system proved to be a valuable tool to perform successful ablation in the presence of a hemi‐azygos continuation.
Effects of Gender and Aging on Differential Autonomic Responses to Orthostatic Maneuvers
Authors: BARANTKE MELANIE , KRAUSS TIMOTHY , ORTAK JASMIN , LIEB WOLFGANG , REPPEL MICHAEL , BURGDORF CHRISTOF , PRAMSTALLER PETER P. , SCHUNKERT HERIBERT , BONNEMEIER HENDRIK
Published: July 2008

Background: There are gender differences in heart rate and blood pressure response to postural change. Also, normal aging is often associated with diminished cardiac autonomic modulation during postural change from supine to upright position. Nevertheless, the exact mechanisms of these physiological alterations are not entirely understood.

Methods: A total of 362 volunteers (206 females, age range: 10–88 years) underwent continuous, noninvasive, beat‐to‐beat blood pressure and ECG recordings in supine and upright position. To calculate spontaneous baroreflex sensitivity (BRS), blood pressure and RR interval fluctuations were reconstructed using the time‐domain sequential technique. Furthermore, mean systolic and diastolic blood pressure, mean heart rate, and frequency‐domain parameters of heart rate variability (low‐frequency power [LF], low‐frequency power in normalized units [LFn] high‐frequency power [HF], high‐frequency power in normalized units [HFn], low‐/high‐frequency ratio [LF/HF], and total power [TP]) were analyzed in both supine and standing positions. To investigate age‐related differences, subjects were divided into four equally sized groups (quartile l: 10–33 years; ll: 34–42 years; III: 43–57 years; and lV: 58–88 years), as well as decades (l: 10–19 years; ll: 20–29 years; lll: 30–39 years; lV: 40–49 years; V: 50–59 years; Vl: 60–69 years; Vll: ≥ 70 years).

Results: A continuous decline in BRS, LF, HF, and TP was observed with increasing age in both male and female subjects, regardless of posture. Gender comparison showed significantly higher values of LF (supine P < 0.001; upright P < 0.05), LFn (supine P < 0.001; upright P < 0.01), and TP (supine P < 0.05; upright P < 0.05) in men than women in supine and standing positions. HF revealed no gender difference and HFn (supine P < 0.001; upright P < 0.05) was larger in women. Log BRS correlated well with log LF and log HF in both supine and standing positions.

Conclusions: There are significant differences in postural cardiac autonomic modulation between men and women, and the degree of autonomic response to orthostatic maneuvers varies with normal aging. These results may explain gender‐ and age‐related differences in orthostatic tolerance.
Congenital Long‐QT Syndrome Concealed by Hypercalcemia in Williams Syndrome
Authors: CZOSEK RICHARD J. , BERUL CHARLES I.
Published: July 2008

We report a case of gene‐positive long‐QT syndrome (KCNH2) in a patient with concomitant Williams Syndrome. The hypercalcemia that developed in association with Williams Syndrome pseudo‐normalized the QTc interval on surface ECG, concealing the clinical and electrocardiographic manifestations of the disease. Initiation of medical therapy for hypercalcemia unmasked the prolonged QT interval, allowing for the diagnosis of long‐QT syndrome to be made.
Constrictive Pericarditis Impressing and Narrowing the Ascending Aorta
Authors: Tugcu Aylin , Yildirimturk Ozlem , Duran Cihan , Aytekin Saide
Published: July 2008

A 77‐year‐old male patient was admitted to our institution with 1‐year history of progressive dyspnea on exertion, and lower extremity edema. His chest x‐ray showed a circumferential pericardial calcification and right‐sided pleural effusion. The electrocardiography revealed atrial fibrillation with low voltage in all derivations and diffuse nonspecific T‐wave inversions. The transesophageal echocardiography showed a thickened pericardium with biatrial enlargement and normal right and left ventricular systolic functions. A thick echogenic structure that caused impression and narrowing of the ascending aorta was observed. Simultaneous right and left heart catheterization showed elevation and equalization of right‐sided and left‐sided diastolic filling pressures, with characteristic dip and plateau. Aortic angiogram showed the ascending aorta was impressed and narrowed by calcified pericardium. Cine magnetic resonance imaging showed pericardial calcifications impressing and narrowing of the ascending aorta. All these findings were consistent with constrictive pericarditis. The patient had no history of tuberculosis, cardiac surgery, or mediastinal irradiation. His HIV antibody test was negative. Marked pericardial thickening and calcifications were evident during pericardiectomy. Histological analysis of the pericardium showed dense collageneous matrix, mild chronic inflammation and calcification. The culture of pericardial tissue revealed no identifiable cause including tuberculosis. The patient was diagnosed as idiopathic constrictive pericarditis. The patient's symptoms and edema decreased remarkably after pericardial stripping. He remained well at 1‐year follow‐up.
Continuing Medical Education Program in Echocardiography
Authors: Fan Pohoey , Kerut Edmund Kenneth , Dearstine Marie , Dottery Patricia , Nanda Navin C.
Published: July 2008

Article Title: Particulate Matter Within the Inferior Vena Cava.
Engagement on the Backroads: Insights for Anthropology and Education
Authors: Gilmore Perry
Published: July 2008

This article is a slightly revised version of the Presidential Address delivered at the annual business meeting of the Council on Anthropology and Education, Washington, D.C., December 1, 2007. [“little communities,” ethnography as picaresque, parrhesia]
Using Visual Stimuli in Ethnography
Authors: Spindler George
Published: July 2008

In this article, the work of George and Louise Spindler is reviewed with visual stimuli ranging from the Rorschach technique and Thematic Apperception Technique to inventions of their own, the Cross‐Cultural Sensitization Technique, the Instrumental Activities Inventory, and the Cross‐Cultural, Comparative, Reflective Interview Technique. The sites of the various researches, the methods of application, and a brief analysis of the results are included. [interview techniques, culture and personality, ethnography and education]
Broken Brains and Broken Homes: The Meaning of Special Education in an Appalachian Community
Authors: Smardon Regina
Published: July 2008

In this article, I explore the meaning of disability within the everyday lives of Clear River third‐grade students. The concept of a disability narrative is developed to explain how expert disability labels shape the experience of academic performance and failure. Previous studies of disability labeling have neglected the life of the label after it has become entextualized. I focus on how the layperson translates the technical language of experts into the moral language of everyday life. [labeling, special education, narrative, discourse, cultural circulation]
“They See Us as Resource”: The Role of a Community‐Based Youth Center in Supporting the Academic Lives of Low‐Income Chinese American Youth
Authors: Wong Nga‐Wing Anjela
Published: July 2008

Based on a 15‐week ethnographic‐based research, this article examines the role of a community‐based youth center in supporting the academic lives of Chinese American youth from low‐income families in an east coast city I call “Harborview.” This study demonstrates the significant role that community‐based organizations play for low‐income immigrant youth in providing them with social capital. This study also challenges the portrayal of Asian Americans as model minorities who do not face any barriers. [Asian American education, community‐based organizations, out‐of‐school‐time programs, social capital]
The Political Coherence of Educational Incoherence: The Consequences of Educational Specialization in a Southern Moroccan Community
Authors: Boum Aomar
Published: July 2008

This article is based on an ethnographic study I conducted in southern Morocco during 2004. I explore the historical, ideological, and cultural background behind educational specialization among Moroccan university students. I describe how French colonial educational policies and postindependence Moroccan national schooling ideologies have created a national system of double standards that: (1) privileges French‐educated urban middle‐ and upper‐class students, (2) emphasizes the Arabization of the national education system, and (3) discriminates against Arabized, largely rural students, which have exacerbated regional educational and socioeconomic inequalities. I finally contend that educational specialization in noncompetitive degrees such as Arabic language and literature, Islamic studies, geography, and general law is the result of an ideological matrix I have termed political coherence of educational incoherence. Political coherence of educational incoherence naturalizes the reliance of certain disfranchised regional groups on a traditional preschool Islamic education that is largely based on memorization and inefficient pedagogy and is unsuitable for the modern educational requirements. [Islamic education, school ethnography, Arabization, school failure, minority education]
Effect of TiO2 Nanopowder on the Sintering Behavior of Nickel–Alumina Composites for Functionally Graded Materials
Authors: Kruft Jonathan G. , Bruck Hugh A. , Shabana Yasser M.
Published: July 2008

The use of TiO2 nanopowder as a sintering aid in a pressureless sintering process has been investigated to improve the compatibility of the shrinkage rate in graded nickel–alumina composites. The results indicate that a 3 wt% TiO2 nanopowder ball mixed into Al2O3 powder substantially reduces sintered porosity in nickel–alumina composite specimens, improving the compatibility of shrinkage rates while increasing Vickers microhardness. Previously developed porosity reduction and sintering models were used to quantify improvement in shrinkage rates. However, the porosity reduction model had to be modified to account for sintering of agglomerated reinforcing particles in alumina‐rich composites. A power law sensitivity of Vickers microhardness to relative density was determined from homogeneous specimens. Vickers microhardness profiles of graded composites were then used to provide an insight into the effects of hydrostatic internal stresses that develop due to differential shrinkage, indicating that substantial hydrostatic stress retards shrinkage, which reduces microhardness at the interface of the nickel‐ and alumina‐rich regions and leads to crack formation without a nanopowder sintering aid.
Spark Plasma Sintering of Zirconium Diborides
Authors: Guo Shu‐Qi , Nishimura Toshiyuki , Kagawa Yutaka , Yang Jenn‐Ming
Published: July 2008

The densification behavior and grain growth of single‐phase ZrB2 ceramics by a spark plasma sintering (SPS) process were systematically investigated. The sintering was conducted at temperatures ranging from 1800° and 1950°C in vacuum under a pressure of 50 MPa. The heating rate and the soaking time varied from 50° to 430°C/min and from 0 to 20 min, respectively. The microstructure was observed by field emission scanning electron microscopy. A near‐fully dense ZrB2 ceramic can be obtained at a lower temperature, within a much shorter time, than those used in conventional hot‐pressing process. The density of the sintered ceramics increases with increase in sintering temperature, heating rate, and holding time. On the other hand, microstructural examination shows a strong dependence of grain growth on sintering temperature, heating rate, and holding time. The fully dense ZrB2 ceramic with fine grain and homogeneous structure could be achieved by the processing conditions as follows: sintering temperature of 1900°C, holding time of 3 min, and heating rate of 200°–300°C/min.
Microwave Dielectric Properties of Low Temperature Firing Bi2Mo2O9 Ceramic
Authors: Zhou Di , Wang Hong , Yao Xi , Pang Li‐Xia
Published: July 2008

Preparation, phase stability, sintering behavior, microwave dielectric properties of single‐phase Bi2Mo2O9 ceramic and its chemical compatibility with Ag have been investigated. The single‐phase Bi2Mo2O9 ceramic can be well densified in the temperature range from 620° to 645°C with relative density about 96%. X‐ray diffraction data show that Bi2Mo2O9 has a monoclinic structure (P21/n), with lattice parameters a=11.9664 Å, b=10.8089 Å, and c=11.8871 Å. When sintering temperature ≥650°C, Bi2Mo3O12 appears as a secondary phase. Pure monoclinic Bi2Mo2O9 ceramic sintered at 620°C for 2 h exhibits good microwave dielectric properties with permittivity about 38, Qf value about 12 500 GHz and temperature coefficient of resonant frequency about +31ppm/°C. The permittivity of single‐phase Bi2Mo2O9 corrected for porosity is about 40.17. However, the reaction between Bi2Mo2O9 and Ag will affect its further application in low‐temperature cofired ceramic.
Effects of Oxidizing Additives on Optical Properties of Bi2O3–B2O3–SiO2 Glasses
Authors: Zhang Yaping , Yang Yunxia , Zheng Jianhua , Hua Wei , Chen Guorong
Published: July 2008

Glasses with compositions (65‐x)Bi2O3–10B2O3–25SiO2–xSb2O3/As2O3/CeO2 (x=0, 0.5, 1) have been prepared by conventional melt quench technique. X‐ray diffraction patterns indicated existence of Bi0 particles dispersed in glass in the glass x=0. Great improvement in transmittance was observed by adding Sb2O3, As2O3, or CeO2. The color lightening effect of these oxidizing additives on bismuth oxide glasses and the variation of UV absorption edge were discussed in terms of specific role these different types of metal ions played in glasses.