bluuebunny/crossref_metadata_2025 huggingface dataset:
Success Factors in New Ventures: A Meta‐analysis*
Authors: Song Michael , Podoynitsyna Ksenia , Van Der Bij Hans , Halman Johannes I. M.
Published: August 2010

Technology entrepreneurship is key to economic development. New technology ventures (NTVs) can have positive effects on employment and could rejuvenate industries with disruptive technologies. However, NTVs have a limited survival rate. In our most recent empirical study of 11,259 NTVs established between 1991 and 2000 in the United States, we found that after four years only 36 percent, or 4,062, of companies with more than five full‐time employees, had survived. After five years, the survival rate fell to 21.9 percent, leaving only 2,471 firms still in operation with more than five full‐time employees. Thus, it is important to examine how new technology ventures can better survive. In the academic literature, a number of studies focus on success factors for NTVs. Unfortunately, empirical results are often controversial and fragmented. To get a more integrated picture of what factors lead to the success or failure of new technology ventures, we conducted a meta‐analysis to examine the success factors in NTVs. We culled the academic literature to collect data from existing empirical studies. Using Pearson correlations as effect size statistics, we conducted a meta‐analysis to analyze the findings of 31 studies and identified the 24 most widely researched success factors for NTVs. After correcting for artifacts and sample size effects, we found that among the 24 possible success factors identified in the literature, 8 are homogeneous significant success factors for NTVs (i.e., they are homogeneous positive significant metafactors that are correlated to venture performance): (1) supply chain integration; (2) market scope; (3) firm age; (4) size of founding team; (5) financial resources; (6) founders' marketing experience; (7) founders' industry experience; and (8) existence of patent protection. Of the original 24 success factors, 5 were not significant: (1) founders' research and development (R&D) experience; (2) founders' experience with start‐ups; (3) environmental dynamism; (4) environmental heterogeneity; and (5) competition intensity. The remaining 11 success factors are heterogeneous. For those heterogeneous success factors, we conducted a moderator analysis. Of this set, three appeared to be success factors, and two were failure factors for subgroups within the NTVs' population. To facilitate the development of a body of knowledge in technology entrepreneurship, this study also identifies high‐quality measurement scales for future research. The article concludes with future research directions.
Incentive Mechanisms, Entrepreneurial Orientation, and Technology Commercialization: Evidence from China's Transitional Economy*
Authors: Li Yuan , Guo Hai , Liu Yi , Li Mingfang
Published: August 2010

Scholars view entrepreneurial orientation as an essential element of high‐performing firms. The extant research has focused extensively on the construct development related to and performance implications of entrepreneurial orientation. Prior research has also identified the significant positive impact of entrepreneurial orientation on technology commercialization. The research community has, however, yet to examine critical antecedents of entrepreneurial orientation and to investigate relevant antecedents and consequences of entrepreneurial orientation in transitional settings such as that of China. Most Chinese firms are embracing significant changes in governance incentive mechanisms as China deepens the economic reform. The extant literature provides limited insight as to how incentive mechanisms such as chief executive officer (CEO) ownership and turnover may affect firm entrepreneurial orientation in China's transitional setting. Furthermore, given the significant changes and uncertainty in the market place, China provides an ideal laboratory to examine the influence of technological turbulence on the relationship between entrepreneurial orientation and technology commercialization. Aimed at filling in these glaring gaps, this study develops a conceptual model, with institutional theory as its underpinning, to examine the relationships among governance incentive mechanisms, entrepreneurial orientation, technological turbulence, and technology commercialization. The empirical results from a sample of 607 Chinese firms reveal several important findings. The CEO ownership has a significant positive effect on entrepreneurial orientation, and CEO turnover frequency has an inverse U curvilinear impact on entrepreneurial orientation. Furthermore, entrepreneurial orientation positively affects technology commercialization, with technological turbulence positively moderating this relationship. This study makes several important contributions. First, the present article brings into sharper focus the differing impacts of CEO ownership and CEO turnover on entrepreneurial orientation. The theoretical deliberation and empirical testing offer useful insights into the formation process of entrepreneurial orientation. Second, the examination of the moderating effect of technological turbulence provides additional richness to the extant literature. In addition, different from prior studies, this study was conducted under China's transitional economy context. By integrating unique institutional arrangements and the turbulent technological environment, two key characteristics of China's transitional economy setting, the study broadened and deepened understanding of key antecedents and consequences of entrepreneurial orientation. The article also discusses managerial implications of the findings and suggests directions for future research.
Beyond Heterodoxy: Dwight Waldo and the Politics–Administration Dichotomy
Authors: Overeem Patrick
Published: August 2010

Dwight Waldo (1913–2000) is commonly known as a “heterodox” critic of the dichotomy between politics and administration. But is this reputation supported by his writings? It seems to be primarily based on The Administrative State (1948) and other early publications, in which he conceptualized politics/administration narrowly as deciding/executing and, indeed, sharply criticized it. Waldo’s later publications, by contrast, offer much broader conceptualizations and a more ambivalent, even positive appraisal of the dichotomy. Such conceptualizations are also found in an important unpublished book Waldo worked on during several phases of his career. On the basis of these published and unpublished writings, we should reconsider Waldo’s reputation and, pursuing his line of reasoning, reconceptualize the politics–administration dichotomy as a layered construct and reappreciate it as a constitutional doctrine.
Beyond Dichotomy: Dwight Waldo and the Intertwined Politics–Administration Relationship
Authors: Svara James H.
Published: August 2010

Dwight Waldo’s conception of the politics–administration question might be better understood as a “relationship” that contains elements of separation and intermixture rather than a “dichotomy,” according to this author‐commentator.To suggest that Waldo came to support the dichotomy presumes agreement about the meaning of the concept that is missing in Waldo’s writings and in the public administration literature.
The Significance of The Administrative State
Authors: Stivers Camilla
Published: August 2010

To mark the 60th anniversary of the appearance of The Administrative State by reexamining the politics–administration debate is confining and ignores Waldo’s grand enterprise to describe the unique context in which American public administration emerged and developed. Instead of bemoaning or strategizing the reconciliation of a supposed schism, modern scholars should appreciate what is, in fact, a natural and necessary tension.
The Politics–Administration Dichotomy: An Empirical Search for Correspondence between Theory and Practice
Authors: Demir Tansu , Nyhan Ronald C.
Published: August 2010

The politics–administration dichotomy has been one of the most disputed theories of public administration. Despite serious critiques, neither the theoretical utility nor the normative power of the dichotomy has totally disappeared over the past decades. The dichotomy has been advocated on the grounds that the dichotomous division of labor and authority between elected and administrative officials increases the democratic accountability and planning ability of public administrators. This article first builds a theoretical model of the politics–administration dichotomy and then evaluates the model using empirical data collected from a nationwide sample of city managers serving in council‐manager local governments. Results of structural equation modeling illustrate that the politics–administration dichotomy fails to obtain its predicted tendencies in actuality. The authors interpret the findings in light of the contemporary public administration literature. The article aims to make a theoretical‐empirical contribution to one of the most challenging questions in public administration.
Rail Safety: Targeting Oversight and Assessing Results
Authors: Plant Jeremy F.
Published: August 2010

Rail safety has emerged as a significant issue in the past two years as a result of two major factors: a statistical lack of improvement in rail safety in the past decade, and a catalytic event in the form of a major derailment involving loss of life at Graniteville, South Carolina, in January 2005. The convergence of long‐term leveling of rail safety indicators and the shock of a major rail accident prompted the Senate Appropriations Committee to ask the Government Accountability Office to assess the oversight role of the Federal Railroad Administration, the modal agency of the U.S. Department of Transportation charged with overseeing rail safety. The report is a reminder of the continuing importance of regulatory activities and the general movement in federal management toward greater use of data and performance measures since the Government Performance and Results Act of 1993.
Managing Markets for Public Service: The Role of Mixed Public–Private Delivery of City Services
Authors: Warner Mildred E. , Hefetz Amir
Published: August 2010

The privatization experience of U.S. municipalities shows declining use of complete contracts and a dramatic rise in mixed public–private delivery (joint contracting) of city services. The analysis here shows that city managers have recognized the need to move beyond a simple dichotomy between market delivery and public planning to an approach that balances concerns with efficiency, market management, and citizen satisfaction. The New Public Management stresses the importance of competition and efficiency, transaction costs economics emphasizes the challenges of contract management, and New Public Service assigns primary concern to citizen engagement. Nonetheless, city managers see the need to balance all three. The analysis shows the evolution of a middle position where city managers integrate markets with public delivery and give greater attention to citizen satisfaction in the service delivery process.
Improving the Managerial Capacity of the Federal Government: A Public Administration Agenda for the Next President
Authors: Stanton Thomas H.
Published: August 2010

The reputation of a president can be enhanced or diminished depending on the quality of federal management. This transition memorandum draws on the insights of the fellows of the National Academy of Public Administration. It urges the next president to (1) set a tone and strengthen organizational infrastructure to promote effective management across government, (2) create an office to monitor potential major risks and ensure adequate response, and (3) pass on to his successor more capable government than he found. Only then can the incoming administration form the basis for short‐term success and longer‐term effectiveness to implement the president’s policy agenda.
A Quiet Revolution or a Flashy Blip? The Real ID Act and U.S. National Identification System Reform
Authors: Ni Anna Ya , Tat‐Kei Ho Alfred
Published: August 2010

In 2005, Congress passed the Real ID Act despite decades of stalemate in reforming the U.S. national ID system. Using John Kingdon’s policy streams framework, the authors examine the development of reform ideas, the opening of a policy window and the shift in the national mood after the 9/11 attacks, and the legislative tactics by the George W. Bush administration that led to the passage of the act. The analysis illustrates the significance of policy entrepreneurship in national crises but also raises questions about the permanency of policy reforms and the ethical responsibilities of public administrators in such times.
The FBI, A Hundred‐Year Retrospective
Authors: Vizzard William J.
Published: August 2010

No civilian government agency in the United States has received as much attention from authors as the Federal Bureau of Investigation. Much of the early writing consisted of laudatory pieces that parroted the output of the agency’s extensive public relations apparatus. This was followed by a reactive era of critical literature following the Watergate scandal and the death of J. Edgar Hoover. This article surveys the key literature on this controversial agency, including both perspectives and insider memoirs, Hoover biographies, and recent scholarly works.
The Importance of Subjective Data for Public Agency Performance Evaluation
Authors: Shingler John , Van Loon Mollie E. , Alter Theodore R. , Bridger Jeffrey C.
Published: August 2010

Evaluating public agency performance has typically been based on objective measurements. However, some researchers contend that evaluation is not complete without considering client perceptions of agency performance. This study supports combining subjective client perceptions with objective data in the evaluation process. Survey results and internal performance data are examined for a state agency charged with investigating citizen disputes with utility companies. Regression analyses show that the factors that most influence the client’s satisfaction with agency performance are the client’s perception of how long it took to resolve the dispute, based on survey results, and whether the case was decided in the client’s favor, from the agency’s internal records. The “real” resolution time recorded in the agency’s information system was not significant. These results indicate that subjective data provide valuable information for evaluating agency performance.
An Organizational Echelon Analysis of the Determinants of Red Tape in Public Organizations
Authors: Walker Richard M. , Brewer Gene A.
Published: August 2010

This article adopts an organizational echelon approach to the study of red tape in public organizations and argues that the nature and extent of red tape will vary at different levels of the organizational hierarchy. These propositions are tested with a multiple‐informant survey using a lagged model. The empirical results across the three organizational echelons sampled indicate modest variations in the levels of perceived red tape and major variations in its determinants. Results from the more senior managers uphold prior research findings and hypotheses on the determinants of red tape. This is not surprising because earlier studies typically sampled senior executives. Yet the lower down the organizational hierarchy one travels, the more red tape officials perceive and the more multifaceted the findings on determinants become. The authors conclude that prior empirical work is likely to have underestimated the extent of red tape in public organizations, and oversimplified its determinants. The implications for theory and practice are discussed.
Executive Orders and Administrative Control
Authors: Ferguson Margaret R. , Bowling Cynthia J.
Published: August 2010

One of the key recommendations of the Winter Commission was the empowerment of governors over the executive branch. However, key institutions have not evolved in this direction; the long ballot still exists in most states, and the formal powers of governors have strengthened to their probable capacity. The authors suggest that a quasi‐formal power—the gubernatorial use of executive orders—may be a significant tool for empowering the governor in the state administrative realm. Analyzing all executive orders in 49 states for 2004 and 2005, they find variation in the aggregate use of and functions performed through these orders. Many executive orders do allow the government more direction and control of state bureaucracy. Finally, the authors suggest that the study of executive orders may be necessary to understand gubernatorial power in the executive arena and beyond.
State and Local Fiscal Sustainability: The Challenges
Authors: Chapman Jeffrey I.
Published: August 2010

At the state and local level, fiscal sustainability is the long‐run capability of a government to consistently meet its financial responsibilities. It reflects the adequacy of available revenues to ensure the continued provision of the service and capital levels that the public demands. After examining separate revenue and expenditure trends for state and local governments, this article identifies three specific sets of pressures that affect subnational fiscal sustainability—cyclical, structural, and intergovernmental. It then presents three specific examples of these pressures: Medicaid, pensions and retiree health benefits, and infrastructure. The author asserts that without changes in the fiscal system—in both revenues and expenditures—state and local fiscal sustainability will disappear. It concludes with some potential solutions but argues that the most difficult reform is to ensure that the public understands that there is no such thing as a free lunch.
Atrial Threshold Variability: Implications for Automatic Atrial Stimulation Algorithms
Authors: BIFFI MAURO , SPITALI GIROLAMO , SILVETTI MASSIMO STEFANO , ARGNANI SELINA , RUBINO IDA , FONTANA PIERLUIGI , BARBATO GAETANO , MAZZINI ELENA , DE SANTO TIZIANA , DRAGO FABRIZIO , BORIANI GIUSEPPE
Published: August 2010

Background:

Automatic management of atrial stimulation by verification of atrial threshold (ACM) has recently been made feasible. We investigated circadian atrial threshold variability over the long term and the predictors of successful automatic atrial threshold measurement, in order to provide practical clues for programming ACM features, in such a way as to achieve daily threshold verification and > 99% effective atrial stimulation.

Methods:

Six daily attempts to measure atrial threshold were programmed in patients receiving an EnPulse™ pacemaker (Medtronic Inc., Minneapolis, MN, USA). Atrioventricular (AV) conduction was maximized by programming Search AV+ (SAV+) to a resting Paced AV delay = 400 ms in the first month, and 600 ms thereafter.

Results:

Seventy‐six patients had a median follow‐up of 12 months. Median ACM success was 77%. Concordance between automatically and manually measured thresholds was observed during the entire follow‐up (Rho = 0.82, P < 0.001). Daily variability in atrial threshold was < 0.5 V in > 94% of measurements in the first trimester after implantation, and < 0.5 V in > 99% of measurements thereafter, as well as any time after pacemaker replacement. Atrial threshold was measured on 86% of days: the predictors of ACM failure were AV block (AVB), high%Atrial pacing, and atrial fibrillation. Programming SAV+ to achieve 600 ms resting Paced AV decreased%Vpacing in patients with normal AV conduction and first‐degree AVB, improving the ability to detect atrial threshold.

Conclusions:

The reliability of ACM is high over a long follow‐up. On the basis of atrial threshold variability, a practical approach to ACM programming should be two daily atrial threshold measurements in patients with normal AV conduction and%Ap ≤ 40%, or with normal sinus activity and AVB, whereas 3–4 measurements should be recommended in patients with first‐degree AVB and%Ap > 40% or with recurrent atrial fibrillation and AVB. The lowest adapted stimulation output should achieve at least threshold +1 V in the first trimester after implantation, then threshold +0.5 V thereafter, in order to achieve > 99.5% effective atrial stimulation.
Left Ventricular Endocardial Pacing: A Transarterial Approach
Authors: REINIG MICHAEL , WHITE MELVIN , LEVINE MARC , CHA RIDO , CINEL ISMAIL , PURNACHANDRA JASTI , GOLDFARB ROY , YANG ZHONGPING , MULLIGAN LARRY , PARRILLO JOSEPH , GESSMAN LAWRENCE
Published: August 2010

Introduction:

We tested the feasibility of a new technique of direct left ventricular endocardial lead placement across the aortic valve in a chronic (six month) pig model. The potential for aortic valve damage, systemic embolization, and pacing lead maturation and function within the left ventricle are unknown.

Methods:

Ten minipigs were successfully implanted with a transaortic left ventricular lead (Medtronic CapSureFix®, Minneapolis, MN, USA) placed in the left ventricular apex via the carotid artery. Each pig received either a polyurethane (n = 5) or silicone (n = 5) lead. Post implant each pig received clopidogrel and aspirin for seven days. After six months all surviving pigs underwent thorough necropsy.

Results:

Each pig had adequate sensing (12.1 ± 4 mV) and pacing thresholds (0.79 ± 0.2 @ 0.5 V) at implant. Postoperatively two pigs died of a respiratory illness. One pig died postoperatively due to sepsis. At the six‐month follow‐up, all surviving pigs (n = 7) were in a healthy state. Of the pigs without dislodgement (n = 5) there was adequate sensing, but a rise in pacing thresholds. Echocardiography revealed a normal ejection fraction and only trace to mild aortic insufficiency in all pigs. Of the seven surviving pigs there were no thromboembolic events noted. One silicone lead was noted to have thrombosis along the lead screw and shaft.

Conclusion:

Direct transaortic placement of a left ventricular lead is feasible. After six months, there was no significant aortic regurgitation and no evidence of thromboembolism despite no anticoagulation. Lead function was acceptable and only one silicone lead (and no polyurethane lead) was noted to have significant thrombosis.
Accelerometer‐Derived Time Intervals during Various Pacing Modes in Patients with Biventricular Pacemakers: Comparison with Normals
Authors: MARCUS FRANK I. , SORRELL VINCENT , ZANETTI JOHN , BOSNOS MIKE , BAWEJA GURPREET , PERLICK DOUG , OTT PETER , INDIK JULIA , HE DING SHENG , GEAR KATHY
Published: August 2010

Introduction:

Changes due to biventricular pacing have been documented by shortening of QRS duration and echocardiography. Compared to normal ventricular activation, the presence of left bundle branch block (LBBB) results in a significant change in cardiac cycle time intervals.
Some of these have been used to quantify the underlying cardiac dyssynchrony, assess the effects of biventricular pacing, and guide programming of ventricular pacing devices. This study evaluates a simple noninvasive method using accelerometers attached to the skin to measure cardiac time intervals in biventricularly paced patients.

Methods:

Ten patients with biventricular pacemakers previously implanted for congestive heart failure were paced in the AAI mode, then in atrioventricular (AV) sequential mode from the right and left ventricles followed by biventricular pacing. Simultaneous recordings were obtained by 2D, Doppler echocardiography as well as by accelerometers. Similar recordings were obtained from 10 gender, aged matched, normal controls during sinus rhythm.

Results:

Compared to normals, heart failure patients paced in AAI mode had prolonged isovolumetric contraction time (IVCT), shorter ventricular ejection time (LVET), and prolonged isovolumetric relaxation (IVRT). With biventricular pacing the IVCT decreased, but the LVET and IVRT did not change significantly. There was excellent correlation between the echo and accelerometer‐measured intervals.

Conclusions:

Shortening of the IVCT measured by an accelerometer is a consistent time interval change due to biventricular pacing that probably reflects more rapid acceleration of left ventricular ejection. The accelerometer may be useful to assess immediate efficacy of biventricular pacing during device implantation and optimize programmable time intervals such as AV and interventricular (VV) delays.
Comparison of Microvolt T‐Wave Alternans Measurements Using Atrial Pacing Compared to Atropine Administration
Authors: WEBER STEFAN , SCHWAB JÖRG O.
Published: August 2010

Background:

Microvolt T‐wave alternans (MTWA) has been associated with malignant ventricular arrhythmias in patients (pts) with structural heart disease. MTWA has been shown to be a strong heart rate‐dependent arrhythmia marker. However, in clinical practice some pts in which MTWA should be assessed are unable to perform physical exercise to increase heart rate due to various reasons.

Methods:

In this study, we investigated the feasibility of noninvasive MTWA measurement by using intravenous atropine to increase heart rate and compared the results to MTWA measurement by right atrial (RA) pacing during electrophysiologic (EP) study in 27 consecutive pts (53 ± 14 years; nine women). Determining the arrhythmia event‐rate, a follow‐up of 18 months was performed in all pts.

Results:

Using atropine, five pts (18%) did not reach the target heart rate (105 bpm). In the remaining group of pts, concordant results for MTWA assessment could be found in 21 pts (96%). Comparing MTWA positive tests there were slightly higher amplitudes using right atrial (RA) pacing than atropine (7.0 ± 2.3μV vs 6.3 ± 2.2μV, P = 0.03; r = 0.97). During follow‐up all pts with a positive MTWA test had documented ventricular arrhythmias. There were no arrhythmic events in the MTWA negative group.

Conclusion:

Whenever target heart rate for MTWA evaluation is obtained by intravenous atropine, the results are comparable to RA pacing. In using atropine there has been observed no pharmacologically influenced increase of MTWA voltage leading to false positive MTWA results. Therefore the use of atropine can be recommended as a safe, non‐invasive, and reliable method for MTWA assessment.
Exercise Does Not Increase QTcmax and QTcd in Diabetic Patients with Autonomic Neuropathy
Authors: YAZICI MEHMET , OZDEMIR KURTULUS , ALTUNKESER BULENT BEHLUL , YAZICI RAZIYE , KAYRAK MEHMET , ULGEN MEHMET SIDDIK , ALIHANOGLU YUSUF , GOK HASAN
Published: August 2010

Background:

The purpose of this study was to examine the effects of exercise on maximum QTc interval (QTcmax) and QTc dispersion (QTcd) in diabetic patients without clinically evident heart disease.

Methods

: Seventy‐six diabetic patients who had no coronary artery disease or hypertension (group I; mean age 48 ± 9 years old) and 40 healthy volunteers (group II; mean age 46 ± 13 years old) were enrolled in the study. Cases with clinically evident heart disease were excluded from the study. Resting 12‐lead electrocardiogram (ECG) and maximal treadmill exercise test (according to Bruce protocol) were performed in all cases. The QTcmax interval was determined at rest (RQTcmax) and during peak exercise (PQTcmax). Also, the QTcd was measured at rest (RQTcd) and during peak exercise (PQTcd). Autonomic neuropathy was assessed by measuring the heart rate variability (HRV).

Results

: There was no significant difference between clinical characteristics of two groups. In group I, HRV parameters were significantly lower than group II. RQTcd, PQTcd, RQTcmax, and PQTcmax were significantly longer in group I (56 ± 16 vs 34 ± 11; P< 0.001, 62 ± 22 vs 40 ± 15; P < 0.001, respectively). In diabetic patients, there was no significant difference between RQTcmax and PQTcmax (428 ± 19 vs 420 ± 31; P > 0.05), and no significant difference was present between RQTcd and PQTcd (56 ± 16 vs 62 ± 22; P > 0.05, respectively).

Conclusion

: Exercise does not affect QTcd in patients with diabetes mellitus and without clinically evident heart disease.
Tilt Training: Does It Have a Role in Preventing Vasovagal Syncope?
Authors: GUREVITZ OSNAT , BARSHESHET ALON , BAR‐LEV DAVID , ZIMLICHMAN EYAL , ROSENFELD GAIL F , BENDERLY MICHAL , LURIA DAVID , AMITAL HOWARD , KREISS YITSHAK , ELDAR MICHAEL , GLIKSON MICHAEL
Published: August 2010

Background:

Vasovagal syncope is one of the most common medical conditions in young adults. Previous trials have shown effectiveness of tilt training in treating this condition. We conducted a prospective, randomized study in order to evaluate the role of tilt‐training in young adults with vasovagal syncope.

Methods:

Forty‐six soldiers (mean age 19.4 ± 0.8 years, 25 males), with a clinical diagnosis of vasovagal syncope supported by positive tilt test, were randomized to either three months of daily tilt training (treatment group), or no training (control group). Patients in both groups were instructed to increase fluid and salt intake, and to refrain from syncope‐inducing situations, such as prolonged standing.

Results:

Compliance, defined as performing 50% or more of the tilt training daily sessions, was 91% during the first month, and declined to 58% during three months. Treatment group patients had a median (interquartile range) of 5.0 (0.5–16.0) syncope episodes during one‐year follow up, compared to a median of 2.0 (0–6.0) episodes in the control group (P = 0.737). Also, there was no difference in time to first syncope after randomization between groups: a median of 1.0 (0.5–2.0) month in the treatment group, compared to 0.8 (0.5–2.0) month in the control group (P = 0.336).

Conclusions:

Adding daily three‐month tilt training to modifications in lifestyle does not improve treatment results in young adults with vasovagal syncope. Good compliance is difficult to achieve in a tilt training program.
Spatial and Topologic Distribution of Verapamil‐Sensitive Atrial Tachycardia Originating from the Vicinity of the Atrioventricular Node
Authors: KOYAMA JUNJIROH , YAMABE HIROSHIGE , TANAKA YASUAKI , MORIHISA KENJI , UEMURA TAKASHI , KAWANO HIROAKI , OGAWA HISAO , ODAGAWA YUKINARI , HONDA TOSHIHIRO , HONDA TAKASHI
Published: August 2010

Background:

Little information exists regarding the precise distribution of verapamil‐sensitive atrial tachycardia originating from the vicinity of the atrioventricular node (V‐AT).

Methods:

In 12 patients with V‐AT, we examined the spatial and topologic distribution of tachycardia origin relative to the His bundle (HB) site. The V‐AT origin was divided into six areas: anterior (A‐HB), posterior (P‐HB), superior (S‐HB), inferior (I‐HB), lateral (L‐HB), and septal (SP‐HB) portion of HB catheter. Three dimensional distance between the distal pair of the electrodes of HB catheter and that of V‐AT origin (DIS) was obtained by calculating the distances on the right and left anterior fluoroscopic images. Topologic distribution was expressed as the interval between the onset of the atrial electrogram of V‐AT origin and that of HB catheter (INT).

Results:

The tachycardia origin was observed at the P‐HB in four, S‐HB in two, I‐HB in two, SP‐HB in three, and L‐HB in one patient. The tachycardia cycle length, DIS, and INT were 369 ± 67 ms, 12 ± 3 mm, and −12 ± 8 ms, respectively. After successful ablation of initial V‐AT (1st V‐AT), V‐AT with a different origin (2nd V‐AT) was induced in five patients. The tachycardia origin, tachycardia cycle length, DIS, and INT of the 2nd V‐AT (P‐HB in three, S‐HB in one, and SP‐HB in one patient; 333 ± 66 ms, 8 ± 3 mm, and −11 ± 4 ms, respectively) were not different from those of 1st V‐AT.

Conclusions:

V‐AT often shows a shift in tachycardia origin to another site where the spatial and topologic distributions are similar to those of 1st V‐AT.
Psychological Intervention Following Implantation of an Implantable Defibrillator: A Review and Future Recommendations
Authors: PEDERSEN SUSANNE S. , VAN DEN BROEK KRISTA C. , SEARS SAMUEL F.
Published: August 2010

Background:

The medical benefits of the implantable cardioverter defibrillator (ICD) are unequivocal, but a subgroup of patients experiences emotional difficulties following implantation. For this subgroup, some form of psychological intervention may be warranted. This review provides an overview of current evidence on the efficacy of psychological intervention in ICD patients and recommendations for future research.

Methods:

We searched the PubMed and PsycInfo databases in the period between January 1980 and April 2007, using a set of a priori determined keywords. Based on the search and a hand search of the reference lists of the included articles, we identified nine studies that fulfilled the inclusion criteria.

Results:

The majority of studies used a randomized controlled trial design, but studies varied considerably in sample size, response, attrition rate, and type of intervention. However, most interventions were multifactorial, using cognitive behavioral therapy as one of the mainstays of treatment. Overall, psychological interventions seem to have little impact on shocks and heart rate variability. Some studies found a decrease in depressive symptoms and gains in quality of life, but the most notable effects are seen in improved exercise capacity and reductions in anxiety. Effect sizes for changes in anxiety in the intervention group ranged from small to large compared to small in the usual care group, using Cohen's effect size index.

Conclusions:

Preliminary evidence from small‐scale intervention trials suggests that psychological intervention is worthwhile in ICD patients. Nevertheless, large‐scale, well‐designed trials are warranted to substantiate these findings. A multifactorial approach using a cognitive behavioral component paired with exercise training is likely to be the most successful.
Retrieval of Pacemaker Lead Tip Embolized into the Distal Pulmonary Arterial Bed during Extraction Procedure
Authors: GOLZIO PIER GIORGIO , BONGIORNI MARIA GRAZIA , GIUGGIA MARCO , VINCI MELISSA , GAZZERA CARLO , BREATTA ANDREA DORIGUZZI
Published: August 2010

A patient required lead extraction of a dual chamber implantable cardioverter defibrillator system for a chronic pocket infection. Using a right subclavian approach, the right ventricular leads were removed by dilation/counter traction. During the procedure, the tip of the atrial lead was cut and, while the body of the lead was extracted, the tip embolized into a distal branch of the right pulmonary artery. Despite its distal location, we were able to extract the lead tip by an Amplatz goose neck snare kit for intravascular foreign body retrieval, commonly used by interventional radiologists, in cooperation with our radiology staff.
Needle Directed Re‐entry to Cross a Subclavian Occlusion Following Failed Microdissection
Authors: WORLEY SETH JOSEPH , GOHN DOUGLAS CHARLES , PULLIAM ROBERT WARD
Published: August 2010

Patients with existing internal cardioverter defibrillators (ICDs) often require upgrading to a biventricular ICD for treatment of congestive heart failure. Placement of a left ventricular (LV) lead can be technically challenging in the best of circumstances. A subclavian vein stenosis or occlusion related to previously placed leads adds a major obstacle to a successful implant. We report a technique to implant an LV lead from the same side as the existing ICD system despite failed microdissection of a complete occlusion of the subclavian vein.
Characterization of Human Coronary Sinus Valves by Direct Visualization during Biventricular Pacemaker Implantation
Authors: ANH D.J. , EVERSULL CHRISTIAN S. , CHEN HENRY A. , MOFRAD PIROOZ , MOURLAS NICHOLAS J. , HARDWIN MEAD R. , ZEI PAUL C. , HSIA HENRY H. , WANG PAUL J. , AL‐AHMAD AMIN
Published: August 2010

Background: The precise reasons for failure to cannulate the coronary sinus during biventricular device implantation are unknown. Visualization of the coronary sinus ostium during electrophysiology procedures may enhance understanding of how unusual anatomy can affect successful cannulation of the coronary sinus.

Objectives: The aim of this study was to describe the morphology of valves at the coronary sinus ostium (CSO) visualized directly with an illuminated fiberoptic endoscope during implantation of biventricular devices.

Methods: The coronary sinus anatomy of one hundred consecutive patients undergoing implantation of biventricular devices was investigated using a fiberoptic endocardial visualization catheter (EVC).

Results: The CSO was clearly visualized in 98 patients using the EVC. A Thebesian valve was seen in 54% of these. Almost all Thebesian valves were positioned at the inferior (61%) or posterior (33%) aspect of the CSO. Only six patients had Thebesian valves that covered more than 70% of the CSO, but all were successfully implanted with a transvenous left ventricular pacing lead after cannulating the coronary sinus under direct visualization.

Conclusions: Over half of patients undergoing biventricular device implantation have identifiable Thebesian valves. Even valves covering the majority of the ostial area may be traversed using direct visualization and modern catheterization techniques.
Pacemaker Malfunctions in Danon's Disease
Authors: MARRAS ELENA , SCIARRA LUIGI , BOCCHINO MANUELA , DELISE PIETRO
Published: August 2010

We describe a case of a 30‐year‐old man with Danon's disease, an X‐linked genetic disorder due to deficiency of lysosomal‐associated membrane protein 2 with secondary intracytoplasmatic glycogen and autophagic material storage. This disease is characterized by skeletal muscle involvement, mental retardation, ophthalmic abnormalities, and cardiac disease. In this patient, cardiac involvement was characterized by hypertrophic cardiomyopathy in young age, preexcitation, and parossistic atrioventriular block. The patient underwent to an implantable cardioverter defibrillator implantation for conduction disorders and for primary prevention of sudden death, a frequent event in Danon's disease. This case report describes cardiac involvement with conduction disorders and multiple pacemaker malfunctions in Danon's disease.
Mechanisms of Ventricular Fibrillation Initiation in MADIT II Patients with Implantable Cardioverter Defibrillators
Authors: ANTHONY RYAN , DAUBERT JAMES P. , ZAREBA WOJCIECH , ANDREWS MARK L. , McNITT SCOTT , LEVINE ETHAN , HUANG DAVID T. , HALL W. JACKSON , MOSS ARTHUR J. ,   For The Multicenter Automatic Defibrillator Implantation Trial‐II (MADIT‐II) Investigator
Published: August 2010

Background:

The availability of stored intracardiac electrograms from implantable defibrillators (ICDs) has facilitated the study of the mechanisms of ventricular tachyarrhythmia onset. This study aimed to determine the patterns of initiation of ventricular fibrillation (VF) in Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients along with associated electrocardiogram (ECG) parameters and clinical characteristics.

Methods:

Examination of stored electrograms enabled us to evaluate the rhythm preceding each episode of VF and to calculate (intracardiac) ECG parameters including QT, QT peak (QTp), coupling interval, and prematurity index.

Results:

Sixty episodes of VF among 29 patients (mean age 64.4 ± 2.5 years) were identified. A single ventricular premature complex (VPC) initiated 46 (77%) episodes whereas a short‐long‐short (SLS) sequence accounted for 14 (23%) episodes. Of the 29 patients studied, 23 patients had VF episodes preceded by a VPC only, two patients with SLS only, and four patients with both VPC and SLS‐initiated episodes. There were no significant differences between initiation patterns in regards to the measured ECG parameters; a faster heart rate with SLS initiation (mean RR prior to VF of 655 ± 104 ms for SLS and 744 ± 222 ms for VPC) approached significance (P = 0.06). The two patients with SLS only were not on β‐blockers compared to 83% of the VPC patients.

Conclusion:

Ventricular fibrillation is more commonly initiated by a VPC than by a SLS sequence among the MADIT II population. Current pacing modes designed to prevent bradycardia and pause‐dependent arrhythmias are unlikely to decrease the incidence of VPC‐initiated episodes of VF.
Risk of Interference from Transcutaneous Electrical Nerve Stimulation on the Sensing Function of Implantable Defibrillators
Authors: HOLMGREN CHRISTINA , CARLSSON TOBIAS , MANNHEIMER CLAS , EDVARDSSON NILS
Published: August 2010

Background:

The use of transcutaneous electrical nerve stimulation (TENS) for pain relief is increasing. At the same time the implantable cardioverter defibrillator (ICD) is a routine treatment for malignant tachyarrhythmias. Today patients often need devices for more than one condition, and consideration must be given to the interaction between them. We studied the risk of interference between TENS and the ICD function.

Methods and Results:

Thirty patients who had received an ICD underwent a test protocol including TENS at the mammilla and hip levels, at two energy levels, and at the highest comfortable stimulation level. The effects of TENS on the electrocardiogram lead II, intracardiac electrograms, and the ICD marker channels were analyzed. Disturbance from TENS on the sensing function was seen at all stimulation attempts. Interference between the systems was observed in 16 patients. In eight patients (27%) the interpretation was VT/VF and in 14 patients (47%) as ventricular premature extra beats. Other kinds of interactions were seen in five patients (16%). Each patient could have more than one kind of interference.

Conclusions:

Noise reversion and undersensing might prevent the ICD from delivering shock when it should and the interpretation as VT/VF could result in inappropriate shocks. Because of the potentially serious consequences of interference we do not recommend the use of TENS in patients with ICD.
Left Ventricular Dysfunction after Cardiac Resynchronization Therapy in Congenital Heart Disease Patients with a Failing Systemic Right Ventricle
Authors: KIESEWETTER CHRISTOPH , MICHAEL KEVIN , MORGAN JOHN , VELDTMAN GRUSCHEN R
Published: August 2010

Background:

Cardiac resynchronization therapy is rapidly emerging as an effective strategy for managing ventricular dysfunction and heart failure associated with congenital heart disease. Indications for therapy, optimal lead placement, and late outcomes are however lacking.

Methods:

We present three patients, one with Mustard procedure and two with congenitally corrected transposition of great arteries, who developed subpulmonic ventricular dysfunction 3–6 months after biventricular pacing ± implantable cardioverter defibrillator implantation, despite initial favorable result of resynchronization therapy. Possible factors for adverse outcome are relatively high pacing rate, unfavorable alteration of torsional contraction, and increased atrioventricular valve regurgitation due to suboptimal placement of larger diameter defibrillation leads.

Results:

Careful evaluation of patients, particularly indications for therapy, need to be rigorous; assessment of hemodynamic response at the time of implant and appropriate programming may improve the effectiveness of cardiac resynchronization therapy (CRT) in this patient population.

Conclusion:

Our case series emphasizes the need for a registry in the absence of randomized controlled trials, in order to identify patients who benefit most from CRT, and, importantly, recognize subgroups that respond poorly.
Rate Responsive Pacemakers: A Rapid Assessment Protocol
Authors: SHABER JUSTIN D. , FISHER JOHN D. , RAMACHANDRA INDIRESHA , GONZALEZ CHRISTIAN , ROSENBERG LAUREN , FERRICK KEVIN J. , GROSS JAY N. , KIM SOO G.
Published: August 2010

Background:

Rate responsive (RR) pacemakers are commonly implanted with nominal conservative factory‐set responsiveness, which is usually accepted because established exercise protocols are time‐consuming. We aimed for efficient assessment of RR pacemaker settings.

Methods:

We tested exercise heart rates in controls and paced patients using a brief exercise test that approximates real‐life levels of exertion. The test used a nonmotorized treadmill: 30 seconds walking at patient‐determined speed followed by 15 seconds brisk exertion. Subjects totaled 110: 26 with RR pacemakers; 22 with non‐RR pacers; 27 “sick” nonpaced control patients; and 35 healthy controls. Heart rate (HR) was measured prior to exercise, after 30 seconds of casual walk, after 15 seconds of brisk walk, and 1 minute into recovery. Testing required <5 minutes from set‐up to recovery.

Results:

The 26 RR pacer patients had a mean HR at rest = 74 ± 10 beats per minute (bpm), walk = 87 ± 14, and brisk = 94 ± 18 (increase 27%). Non‐RR pacer patients (n = 22): rest = 73 ± 12 bpm, walk = 88 ± 14, and brisk = 94 ± 17 (increase 24.3%, P = 0.60 vs RR patients). “Sick” controls (n = 27): rest = 78 ± 14 bpm, walk = 102 ± 17, and brisk = 117 ± 18 (increase 51.9%, P< 0.001 vs RR pts). For the healthy controls, HRs were at rest 83+/11 bpm, walk = 104 ± 12, and brisk = 117 ± 13 (P< 0.001 compared to both paced groups; P = NS vs sick controls).

Conclusions:

Nominal RR settings may be suboptimal for many patients. The nonmotorized treadmill test allows quick and inexpensive assessment of RR programming, with the potential for efficient RR optimization.
Evaluation of Fractal‐Coated Temporary Pacing Leads in the Early Postoperative Course
Authors: MELLERT FRITZ , KONIETZKO PETER , SCHNEIDER CHRISTIAN , GERSING EBERHARDT , KREUZ JENS , BALTA OSMAN , PREUSSE CLAUS J. , WELZ ARMIN
Published: August 2010

Background:

The performance of temporary pacing wires is still limited by capture and sensing problems. Fractal coating can enhance electrical properties and reliability. We therefore investigated fractal‐laminated wires in comparison with conventional wires.

Methods:

In 21 patients two unipolar, fractal‐coated pacing wires (fe) and one conventional bipolar electrode (se) were implanted in ventricular position. Afterward pacing threshold (V), R‐wave sensing (mV), lead impedance (ohm), and slew‐rate (mV/s) were measured. Loss of capture or sensing and dislocation was documented. fe wires were examined with energy dispersive x‐ray diffraction (EDX)‐analysis and scanning electrode microscopy (SEM).

Results:

Failure in pacing was less frequent in fe wires. Also fe leads had lower pacing thresholds at implantation (0.76 ± 0.15 V vs 1.51 ± 0.95 V, P< 0.0001) and afterward. Furthermore fe wires showed lower increase of pacing threshold/time (0.25 V/day vs 0.42 V/day). R‐wave sensing and slew‐rate values in the fe group on day of operation (5.81 ± 4.80 mV; 0.63 ± 0.71 V/s) were lower than in the se group (10.37 ± 6.89 mV; 1.85 ± 1.71 V/s P< 0.0001) and afterward. Nevertheless, decrease of amplitude/time was lower in fe wires (0.17mV/day vs 0.46 mV/day). fe wires always had lower impedance values.

Conclusions:

Lower pacing threshold and increase of threshold/time in fe wires indicate more reliable function. Initial lower sensitivity values are still not understandable and must be investigated. However, fe wires, constancy of sensing and impedance values was more stable, so fe epicardial wires can be recommended for safe and feasible use.
Coronary Vein Angioplasty with Noncompliant Balloon for Resistant Coronary Vein Stenosis During Left Ventricular Lead Implantation
Authors: CHAUHAN KETUL , SAYAD DANY , BOWERMAN RICHARD , BAROLD S. SERGE
Published: August 2010

This report describes a patient who underwent cardiac resynchronization therapy (CRT) in the setting of a severe stenosis in the lateral coronary vein that prevented passage of a left ventricular lead. The stenosis was unresponsive to standard compliant balloon dilatation but was successfully treated with a noncompliant balloon. Venoplasty with noncompliant balloon should be considered for resistant coronary vein stenosis encountered during CRT device implantation.