bluuebunny/crossref_metadata_2025_split huggingface dataset:
“Tuned” Defibrillation Waveforms Outperform 50/50% Tilt Defibrillation Waveforms: A Randomized Multi‐Center Study
Authors: NATARAJAN SENTHIL , HENTHORN RICHARD , BURROUGHS JEFFERSON , ESBERG DOUGLAS , ZWEIBEL STEVEN , ROSS TERENCE , KROLL MARK , GIANOLA DON , OZA ASHISH 
Published: January 2007

Introduction: A superior performance of a tuned waveform based on duration using an assumed cardiac membrane time constant of 3.5 ms and of a 50/50% tilt waveform over a standard 65/65% tilt waveform has been documented before. However, there has been no direct comparison of the tuned versus the 50/50% tilt waveforms.
Methods: In 34 patients, defibrillation thresholds (DFTs) for tuned versus 50/50% tilt waveforms in a random order were measured by using the optimized binary search method. High voltage lead impedance was measured and used to select the pulse widths for tuned and 50/50% tilt defibrillation waveforms.
Results: Delivered energy (7.3 ± 4.6 J vs 8.7 ± 5.3 J, P = 0.01), stored energy (8.2 ± 5.1 J vs 9.7 ± 5.6 J, P = 0.01), and delivered voltage (405.9 ± 121.7 V vs 445.0 ± 122.6 V, P = 0.008) were significantly lower for the tuned than for the 50/50% tilt waveform. In four patients with DFT ≥15 J, the tuned waveform lowered the mean energy DFT by 2.8 J and mean voltage DFT by 45 V. For all patients, the mean peak delivered energy DFT was reduced from 29 J to 22 J (24% decrease). Multiple regression analysis showed that a left ventricular ejection fraction <20% is a significant predictor of this advantage.
Conclusion: Energy and voltage DFTs are lowered with an implantable cardioverter defibrillator that uses a tuned waveform compared to a standard 50% tilt biphasic waveform.
Noninvasive Classification of Ventricular Preexcitation with Unshielded Magnetocardiography and Transesophageal Atrial Pacing and Follow‐Up
Authors: BRISINDA DONATELLA , FENICI RICCARDO 
Published: January 2007

Background: Ventricular preexcitation (VPx) is usually localized noninvasively by means of electrocardiogram (ECG) algorithms, which vary in their concordance levels. Contactless magnetocardiography (MCG) has been used as an alternate 3‐dimensional (3D) method of accessory pathways (AP) localization. The sensitivity of MCG can be increased for preoperative evaluations and planning of ablation procedures by combining it with transesophageal pacing (TEP) and electrophysiological (EP) studies. This study compared the accuracy of VPx localization with MCG with ECG algorithms, and examined the increment in diagnostic accuracy achievable with TEP.
Methods: Multisite mapping from the anterior chest wall was performed with a 36‐channel MCG system. TEP allowed the evaluation of anterograde conduction properties and inducibility of arrhythmias. The reproducibility of the test and follow‐up was examined in 88 patients with Wolff–Parkinson–White (WPW) syndrome. The accuracy of MCG localization was reevaluated during pacing‐induced maximal VPx in 36 patients in whom, during MCG, the degree of VPx was highest during TEP. The gold standard for validation was effective ablation of the AP.
Results: The MCG classification of VPx was accurate in 94% of AP, versus 64% and 67% with ECG, during sinus rhythm and during pacing‐induced maximal VPx, respectively. In 4.5% of cases with unclear ECG localization, MCG suggested a complex septal VPx. In all patients with successful ablations, the 3D MCG localization of the AP corresponded to the ablation site.
Conclusions: MCG was more accurate than ECG for the classification of VPx and provided additional information in the non‐invasive EP assessment of patients with WPW syndrome.
High Prevalence of False Chordae Tendinae in Patients Without Left Ventricular Tachycardia
Authors: GUALANO SARAH K. , BOLLING STEVEN F. , GORDON DAVID , WILSON ALLECIA , BACH DAVID S. 
Published: January 2007

Background: Left ventricular (LV) false chordae tendinae (false chords) have been implicated as a source of idiopathic left (IL) ventricular tachycardia (VT). However, it is unknown whether pretest bias contributes to an apparent association with disease. The purpose of this study was to determine the prevalence of false chords on direct inspection of the LV endocardium.
Methods: In a prospective series, 75 hearts were examined to identify and characterize false chords, including 20 specimens examined at autopsy and 55 consecutive patients undergoing mitral valve surgery. Medical records were reviewed for history of VT, including ILVT.
Results: Of 75 patients whose hearts were studied, none had a history of ILVT and only 5 had a history of any VT. False chords were present in 34 of 75 (45%) hearts, including 13 of 20 (65%) at postmortem and 21 of 55 (38%) examined at surgery (P = 0.07). The prevalence of false chords was not different among patients with (3 of 5 [60%]) versus those without (31 of 70 [44% p = 0.65]) a history of VT (P = 0.65).
Conclusions: In this prospective anatomic series, the prevalence of LV false chords on autopsy and surgical inspection was approximately 45% among patients without ILVT. Previously reported associations of false chords with ILVT likely underestimated the prevalence of false chords in a normal population.
Low Doses of Intracoronary Enalaprilat Suppress Reperfusion‐Associated Ventricular Arrhythmias after Primary Percutaneous Coronary Interventions for Acute Myocardial Infarction
Authors: BONNEMEIER HENDRIK , SCHÄFER ULRICH , ORTAK JASMIN , KURZ THOMAS , KATUS HUGO A. , RICHARDT GERT , SCHUNKERT HERIBERT 
Published: January 2007

Background: In the era of early reperfusion therapy, life‐threatening ventricular arrhythmias (VA) remain common after recanalization of an occluded coronary artery. Experimental studies reported that angiotensin‐converting (ACE) inhibitors suppress reperfusion‐induced VA. However, whether ACE inhibitors lower the incidence of reperfusion clinical VA is unknown. We examined the effects of low doses of intracoronary (i.c.) enalaprilat (EN) as an adjunct to direct percutaneous coronary interventions (PCI) on reperfusion VA in the acute phase of myocardial infarction (MI).
Methods: We randomly assigned 22 patients with a first acute MI, who underwent successful direct PCI, to EN, 50 μg, i.c., or placebo (PL), administered immediately after reperfusion. VA were manually edited and counted from 24‐hour Holter recordings begun upon hospital admission.
Results: There were no significant between‐groups differences in clinical characteristics. Mean RR interval before and after PCI, and the incidence of VA before PCI were similar in both groups. After PCI the incidence of reperfusion‐induced VA was significantly lower in the EN‐treated group (VPB/h: PL 29.9 ± 12 vs EN 43.2 ± 42, P < 0.05; couplets/h: EN 0.9 ± 0.7 vs PL 4.1 ± 5.0, P < 0.01; triplets/h: EN 0.3 ± 0.2 vs PL 1.2 ± 1.5, P < 0.05; ventricular tachycardia/h: EN 0.3 ± 0.1 vs PL 0.8 ± 0.5, P < 0.01).
Conclusions: Compared with PL, i.c. EN significantly lowered the incidence of reperfusion‐associated VA. This previously unrecognized antiarrhythmic effect might be an important therapeutic benefit conferred by ACE inhibitors, beyond limitation of infarct size.
Microvolt T‐Wave Alternans During Atrial and Ventricular Pacing
Authors: SHALABY ALAA A. , VOIGT ANDREW , EL‐SAED AIMAN , MAINS MARTIN , SHUSTERMAN VLADIMIR 
Published: January 2007

Introduction: Assessment of microvolt T‐wave alternans (MTWA) by the spectral analysis (SA) method requires the heart rate to be stable within a certain range. This can be achieved by ventricular pacing (VP). We compared MTWA during short‐term VP versus atrial pacing (AP).
Methods: Patients presenting for evaluation of risk of sudden cardiac death underwent an invasive electrophysiologic study. The concordance of results of MTWA‐VP with MTWA‐AP was evaluated, as well as the specificity, sensitivity, negative, and positive predictive values of MTWA‐VP versus MTWA‐AP. The maximum recorded amplitude of MTWA (MValt) in concordant positive results, as well as noise levels in all, were compared in both pacing modes.
Results: We studied 42 consecutive patients, of whom 31 completed both tests (32 by AP, 40 by VP). Compared to AP, VP—MTWA SA had a sensitivity of 93%, specificity of 71%, negative predictive value of 92%, and positive predictive value of 72%. The results were concordant in 25 patients (80%, κ= 0.62, P < 0.001). The noise level was significantly higher during VP than AP (1.4 ± 0.8 vs 1± 0.8, P< 0.01), and there was a trend toward a higher amplitude of TWA by VP (10.7 ± 5.3 vs 7.8 ± 3.9, P = 0.058).
Conclusions: MTWA SA is more likely to be completed during VP than AP. Overall there was concordance between both tests. VP generates higher amplitudes and noise, and a higher percentage of nonnegative results.
Impact of Diabetes on QT Dynamicity in Patients With and Without Myocardial Infarction: The KORA Family Heart Study
Authors: LIEB WOLFGANG , VOSS CHRISTIAN , ORTAK JASMIN , BARANTKE MELANIE , HENGSTENBERG CHRISTIAN , LOEWEL HANNELORE , HOLMER STEPHAN , ERDMANN JEANETTE , SCHUNKERT HERIBERT , BONNEMEIER HENDRIK 
Published: January 2007

Introduction: Patients with diabetes mellitus (DM) have an unfavorable prognosis after myocardial infarction (MI), partially due to a higher risk of sudden cardiac death (SCD). QT dynamicity is an independent predictor of SCD in post‐MI patients. However, the effects of diabetes on QT dynamicity in patients with MI have not been described.
Methods: We studied 468 survivors of MI (67 with DM) from the population‐based MONICA registry (KORA Family Heart Study), Augsburg, Germany, by standardized questionnaire, anthropometry, electrocardiogram (ECG), 30‐minute‐Holter‐ECG‐recordings and echocardiography. In addition, 422 siblings without prior MI (22 with DM) were studied by the same protocol.
Results: Among post‐MI patients, the QT/RR slope was significantly steeper in diabetics than in nondiabetics (0.096 ± 0.057 vs 0.077 ± 0.045; P = 0.002). Likewise, among siblings without MI, the QT/RR slope was steeper in diabetics than in nondiabetics (0.104 ± 0.053 vs 0.080 ± 0.042; P = 0.008). The association of DM with steeper QT/RR slope remained significant in multivariate models in post‐MI patients (β: −0.14; P = 0.004) as well as in individuals without MI (β: −0.10; P = 0.047).
Conclusions: In a large population of survivors of MI and unaffected siblings, patients and siblings presenting with DM exhibited an abnormal QT rate‐dependence, compared with individuals without DM in both groups. Thus, diabetes itself may be a major determinant of ventricular arrhythmias, independently of a previous MI. These observations might in part explain the higher incidence of sudden cardiac death and ventricular arrhythmias in patients with DM.
Abnormal Nocturnal Heart Rate Variability and QT Dynamics in Patients with Brugada Syndrome
Authors: PIERRE BERTRAND , BABUTY DOMINIQUE , PORET PHILIPPE , GIRAUDEAU CEDRIC , MARIE OLIVIER , COSNAY PIERRE , FAUCHIER LAURENT 
Published: January 2007

Background: In Brugada syndrome (BSY), most of the ventricular arrhythmic events are nocturnal, suggesting an influence of the autonomic nervous system.
Methods: In 46 patients (mean age = 41 ± 14 years, 43 men) with electrocardiograms (ECG) consistent with BSY and structurally normal hearts, we measured heart rate variability (HRV) and QT dynamics (QT/RR slopes) on 24‐hour ambulatory ECG. Type 1 BSY‐ECG was spontaneous in 23 (50%) and induced in 23 patients.
Results: History of syncope was present in 23 patients (50%). Programmed ventricular stimulation induced ventricular tachyarrhythmias (VTA) in 13 patients (28%). A single patient developed ventricular tachycardia during a mean follow‐up of 34 months. Compared to a control group matched for age and sex, HRV was decreased over 24 hours and during nighttime in patients with BSY (SDNN 122 ± 44 vs 93 ± 36 ms, P = 0.0008 and SDANN 88 ± 39 vs 54 ± 24 ms, P < 0.0001). QTend /RR slopes were decreased over 24 hours in patients with BSY (0.159 ± 0.05 vs 0.127 ± 0.05, P = 0.003) and particularly at night (0.123 ± 0.04 vs 0.089 ± 0.04, P = 0.0001). QTend /RR slopes were significantly decreased during nighttime in patients with spontaneous versus provoked BSY‐ECG patterns. By contrast, HRV and QT/RR slopes were similar in symptomatic and asymptomatic patients, whether VTA were induced or not.
Conclusions: Patients with a BSY‐ECG pattern had lower HRV and QT/RR slopes than control subjects during nighttime. High‐risk patients with spontaneous BSY‐ECG patterns had the lowest nocturnal QTend/RR slopes. These unique repolarization dynamics might be related to the frequent nocturnal occurrence of VTA in BSY.
Effects of Atrial Tachypacing on Symptoms and Blood Pressure in Severe Orthostatic Hypotension
Authors: KOHNO RITSUKO , ABE HARUHIKO , OGINOSAWA YASUSHI , NAGATOMO TOSHIHISA , OTSUJI YUTAKA 
Published: January 2007

The treatment of severe orthostatic hypotension (OH) is currently unsatisfactory and usually includes various pharmaceuticals to expand the blood volume and promote peripheral vasoconstriction. This study examined the short‐ and intermediate‐term effects of atrial tachypacing (ATP) in patients with severe OH. We implanted dual chamber pacemakers in five patients (mean age 64 ± 7 years; four men), presenting with drug refractory, recurrent syncope, and OH due to panautonomic failure with severe chronotropic incompetence and absence of rate acceleration upon assuming the upright posture. The blood pressure (BP) was measured in the supine and passive upright postures, during sinus rhythm, and during atrial pacing at 90, 100, and 110 ppm, at 1 week and at discharge and/or 3 months after pacemaker implantation. Alleviation of symptoms and a delay in the fall in upright BP were observed in a single patient at 1 week, while at discharge and/or 3 months, all patients were markedly improved. The mean fall in systolic/diastolic BP between supine and upright position decreased from 73 ± 17/46 ± 13 mmHg before, to 56 ± 27/41 ± 30 mmHg during ATP. Although these changes did not reach statistical significance, the time required for the fall in BP lengthened significantly from 2.1 ± 0.2 minutes during sinus rhythm to 9.3 ± 1.5 minutes during ATP (P < 0.001).
Conclusions: At discharge and/or 3 months of follow‐up, ATP conferred beneficial effects on orthostatic BP and alleviated symptoms in patients with severe OH. The short‐term effects of ATP did not reflect its longer‐term effects in four of the five patients.
Difference in Autonomic Nervous Control between Ventricular Septal Defect and Atrial Septal Defect Based on Heart Rate Variability
Authors: HATA TADAYOSHI , MANO SEIKO , KUSUKI MASAFUMI , MATSUURA HIDEAKI , MIYATA MASAFUMI , YAMAZAKI TOSHIO , NAGAOKA SYUNJI 
Published: January 2007

Background: We hypothesized that patients with atrial (ASD) and ventricular septal defects (VSD) have similarly reduced heart rate variability (HRV) since both defects cause similar increases in pulmonary blood flow and right ventricular filling pressure. We examined the correlation between HRV and respiratory frequency (RSA) characteristics and left‐to‐right shunt ratio (Qp/Qs) measured by Doppler echocardiography.
Methods: The study included 83 patients with diagnoses of ASD (n = 43) or VSD (n = 40). The electrocardiogram and respiratory waves were recorded during Doppler echocardiography test, and HRV was measured to calculate the low frequency (LF), high frequency (HF), total frequency (TF), and RSA components, and the LF/HF, RSA/TF, and LF/RSA ratios. Qp/Qs was calculated from Doppler echocardiography and its relationship with HRV parameters was examined by multivariate analysis.
Results: There was a positive correlation between Qp/Qs and LF/RSA in the ASD group, and a negative correlation in the VSD group. In contrast, Qp/Qs correlated negatively with RSA/TF in the ASD group, and positively in the VSD group.
Conclusion: Different effects of respiratory vagal activity on HRV were observed in patients with ASD versus VSD.
Diffusion and spillover of new technology: a heterogeneous‐agent model for cassava in West Africa
Authors: Johnson Michael E. , Masters William A. , Preckel Paul V. 
Published: January 2007

AbstractUnderstanding what determines the geographic spread of innovations can help guide the funding and implementation of research and extension programs. Our approach uses household survey data as model parameters, to simulate behavior across the entire surveyed population and avoid the aggregation bias associated with representative‐farm models. Such a “heterogeneous agent” approach allows us to infer the distribution of a technology's impacts across one set of households, and predict the potential for spreading to another set that shares similar characteristics with respect to natural resource endowments and farming systems. We apply the technique to new cassava varieties in West Africa, finding a strongly poverty‐alleviating impact, with substantial spillover potential from Nigeria to neighboring countries.
Incorporating nutrients into meat demand analysis using household budgets data
Authors: Angulo Ana María , Gil José María 
Published: January 2007

AbstractThe objective of this article is to analyze the Spanish demand for meat, taking into account the consumer's concern about the relationship between food diet and health. This concern is forcing food demand analysts to assume that consumer utility is a function of nutrients instead of simply the food products themselves. Nevertheless, these utility function arguments are not produced in the marketplace but rather at home. As a consequence, in this article household production theory is followed in order to analyze Spanish demand for meat using the Quarterly National Expenditure Survey for 1999. Demands for several meat products (the input in the model) are derived from the translog cost function. Censored regression models are used in the estimation process, since many zero responses are reported. Five broad categories, eight nutrients, and the most relevant socioeconomic variables are considered. Finally, a set of elasticities is calculated with respect to all the variables included in the analysis.
Effective dimensionality and factors affecting crop‐livestock integration in West African savannas: a combination of principal component analysis and Tobit approaches
Authors: Manyong V. M. , Okike I. , Williams T. O. 
Published: January 2007

AbstractCrop‐livestock integration (CLI) to improve natural resource management for increased productivity is evolving in Nigeria and West Africa. Processes in the evolution and factors that influence it still need to be well understood. This article proposes and tests a new framework for measuring the multiple dimensionality of CLI. The framework derives a CLI index using the principal components of its most common single measures; it develops geographic information systems (GIS)‐based village‐level ecological and market factors; and it estimates parameters of factors affecting CLI using the derived index as the dependent variable in a Tobit model. The framework is tested using empirical data from 634 farm households in 11 geo‐referenced villages in the Sudan savanna (SS) and northern Guinea savanna (NGS), Nigeria. Along a north–south (SS to NGS) axis, CLI initially increases, peaking around 11.2°N, and then declines. This latitude probably identifies the boundary below which disease challenge constrains traditional livestock production and CLI. This polynomial pattern of CLI is contrary to an expected linear increase along lines of perceived potentials for rain‐fed crop production. Household resources, GIS‐derived village‐level market factors, and institutional factors also significantly affect CLI. Ecological and institutional factors have most impact on the probability of adoption and use intensities of CLI. The incorporation of GIS‐derived market factors with household and institutional variables in an econometric model offers new opportunities for assessing patterns of evolution of CLI, comparing results across sites, and targeting recommendation domains objectively. A comparison with results from more common methods of running independent models for individual indicators of CLI shows that this new framework is an effective way of reducing the multiple dimensionality of CLI to gain quicker, well‐focused knowledge of the processes of agricultural intensification.
Demand for rural tourism: the effects of quality and information
Authors: Skuras Dimitris , Petrou Anastasia , Clark Gordon 
Published: January 2007

AbstractThe development of rural tourism is regarded as a promising diversification strategy especially for lagging and mountainous areas of the European Union. Research concerning the demand and/or supply of rural tourism services has been limited within the agricultural economics domain despite the significance attached to rural tourism by various rural development policy measures and initiatives. The article examines the expenditure behavior of rural tourists within a framework of demand for composite (heterogeneous) goods. The proposed framework captures the quality of the tourism experience as the commodity's unit value, a quantifiable economic variable, examines its effects on expenditures and allows for the estimation of elasticity in prices regarding expenditure and quantity. Empirical analysis is facilitated by a survey recording the expenditure behavior of 465 tourists in two rural and lagging areas of Greece. The quality of the tourism experience is significantly and positively affected by the income, the source from which information about the trip is retrieved (Internet, newspapers as well as general press and special travel press) and by the amount of information sought by the consumer prior to the trip. In turn, the quality of the tourism experience is the major endogenous factor that positively influences expenditures for rural tourism. Further research is needed before evidence provided in this work can be used to draw policy conclusions and recommendations.