bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prospective Randomized Comparison of Closed Cooled‐Tip versus 8‐mm‐Tip Catheters for Radiofrequency Ablation of Typical Atrial Flutter
Authors: SCHREIECK JUERGEN , ZRENNER BERNHARD , KUMPMANN JOHANNA , NDREPEPA GJIN , SCHNEIDER MICHAEL A.E. , DEISENHOFER ISABEL , SCHMITT CLAUS 
Published: December 2004

Cooled‐Tip vs 8‐mm‐Tip Ablation of Atrial Flutter.
Introduction: Cooled‐tip and 8‐mm‐tip catheters have been found to be more effective than conventional 4‐mm‐tip catheters for radiofrequency (RF) ablation of common atrial flutter. The aim of this study was to compare the efficacy and safety of cooled‐tip and 8‐mm‐tip catheters for flutter ablation in a randomized, prospective study. Methods and Results: In 100 consecutive patients referred for ablation of common atrial flutter, cavotricuspid ablation was performed with a closed cooled‐tip catheter (n = 50) or an 8‐mm‐tip ablation catheter (n = 50). RF current was applied for 60 to 120 seconds at powers of 40 to 50 W with the closed cooled‐tip catheter and in a temperature‐controlled mode (65°C/70 W) with the 8‐mm‐tip catheter. The endpoint was achievement of a bidirectional isthmus conduction block. Cross‐over was performed after 15 unsuccessful RF applications for each of the catheters. Complete bidirectional isthmus block was achieved in 99% of patients. Cross‐over was performed in 11 patients after primary use of the cooled‐tip catheter and in 9 patients after primary ablation with the 8‐mm‐tip catheter. No significant differences were found in the procedure parameters, such as overall RF applications (12.4 ± 11.3 vs 12.9 ± 8.6), ablation duration (42 ± 43 min vs 39 ± 27 min), and fluoroscopy time (17.0 ± 18.7 min vs 15.7 ± 10.7 min). In a mean follow‐up of 8.3 months, 1 patient in the cooled‐tip group and 3 patients in the 8‐mm‐tip group had recurrence of common atrial flutter. Conclusion: Use of the closed cooled‐tip ablation catheter and the 8‐mm‐tip catheter have equal and high efficacy for RF ablation of common atrial flutter.
Effect of Electrical and Structural Remodeling on Spatiotemporal Organization in Acute and Persistent Atrial Fibrillation
Authors: AKAR JOSEPH G. , EVERETT THOMAS H. , KOK LAI‐CHOW , MOORMAN J. RANDALL , HAINES DAVID E. 
Published: December 2004

Spatiotemporal Organization in Atrial Fibrillation.
Introduction: Atrial fibrillation (AF) may originate from discrete sites of periodic activity. We studied the effect of structural and electrical remodeling on spatiotemporal organization in acute and persistent AF. Methods and Results: Atrial effective refractory periods (AERPs) were recorded from five different sites at baseline and after pacing in acute AF (n = 8 dogs) and persistent AF (n = 8). Four persistent AF dogs subsequently were cardioverted to sinus rhythm to allow AERP recovery. Periodicity was quantified by calculating power spectra on left atrial electrograms obtained from a 64‐electrode basket catheter. Left atrial size was measured by intracardiac echocardiography and structural changes were assessed by electron microscopy. Mean AERPs decreased after pacing in acute (128 ± 16 msec to 108 ± 29 msec, P < 0.001) and persistent AF (135 ± 16 msec to 104 ± 24 msec, P < 0.0001). AERP recovery was established after 7 days of sinus rhythm. Structural changes were mild in acute AF, severe in persistent AF, and remained severe after AERP recovery. A single dominant frequency was identified in 94% of acute AF bipoles, 57% in persistent AF, and 76% after AERP recovery. Average correlation coefficient was 0.82 among acute AF bipoles, 0.63 in persistent AF, and 0.73 after AERP recovery. Conclusion: Transition from acute to persistent AF is associated with loss of spatiotemporal organization. A single dominant frequency recruits the majority of the left atrium in acute AF. Persistent AF, however, is associated with structural remodeling and dominant frequency dispersion. Recovery of refractoriness only partially restores spatiotemporal organization, indicating a major role for structural remodeling in the maintenance of persistent AF.
Development of the Cardiac Conduction System as Delineated by minK‐lacZ
Authors: KONDO RICHARD P. , ANDERSON ROBERT H. , KUPERSHMIDT SABINA , RODEN DAN M. , EVANS SYLVIA M. 
Published: December 2004

Introduction: Due to the lack of good molecular markers, for decades the morphogenetic origin of the cardiac conduction system has been a matter of debate. More recently, the spatial expression of minK‐lacZ in the adult mouse heart has been shown, for the larger part, to be coincident with the conduction tissues.
Methods and Results: To trace the embryonic development of this system, we performed an analysis of the expression of this construct throughout early cardiac development. Expression was first seen at the eighth embryonic day. Subsequently, discrete rings were found at the sinuatrial, atrioventricular, interventricular, and ventriculoarterial junctions. With time, the expression became restricted to boundary regions of the heart, such as the hinges of the leaflets of the pulmonary and aortic valves, the atrioventricular rings, and the venous valves, as well as becoming incorporated into the definitive conduction tissues themselves. In the postnatal heart, the areas retaining minK‐lacZ positivity outside of the definitive conduction tissues are known to be the site of origin of abnormal cardiac rhythms, suggesting that ectopic foci may derive from tissues that share a common developmental pathway with the definitive conduction system.
Conclusion: Our findings suggest that the boundary regions between compartments, along with the atrioventricular conduction axis, share a common developmental pathway.
(J Cardiovasc Electrophysiol, Vol. 14, pp. 383‐391, April 2003)
P Wave Polarities of an Arrhythmogenic Focus in Patients with Paroxysmal Atrial Fibrillation Originating from Superior Vena Cava or Right Superior Pulmonary Vein
Authors: KUO JEN‐YUAN , TAI CHING‐TAI , TSAO HSUAN‐MING , HSIEH MING‐HSIUNG , TSAI CHIN‐FENG , LIN WEI‐SHIANG , LIN YUNG‐KUO , DING YU‐AN , JIA‐YIN HOU CHARLES , TSAI CHENG‐HO , CHEN SHIH‐ANN 
Published: December 2004

Introduction: The superior vena cava (SVC) and right superior pulmonary vein (RSPV) are anatomically close structures. Using 12‐lead ECG may facilitate identification of ectopic foci from SVC or RSPV. The aim of this study was to assess whether P wave polarity on surface ECG is helpful in distinguishing an arrhythmogenic focus of paroxysmal atrial fibrillation (AF) from SVC or RSPV.
Methods and Results: Thirty‐four patients with paroxysmal AF from the SVC (group I: 17 patients, 10 men and 7 women; mean age

57 ± 12 years

) or RSPV (group II: 17 patients, 15 men and 2 women, mean age

62 ± 14 years

) underwent electrophysiologic study and radiofrequency (RF) catheter ablation. All of the AF foci were confirmed by successful ablation. P wave polarities on surface ECG inferior leads were positive during sinus rhythm and ectopic beats in both groups. Leads I, aVR, aVL, and V1 were further analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in predicting an arrhythmogenic focus of AF from SVC or RSPV were provided. P wave polarity in lead aVR was negative in all 34 patients. P wave polarity in lead V1 was positive in 47.1% of SVC ectopy but positive in all RSPV ectopy. The combination of a biphasic or isoelectric P wave polarity in lead V1 or a biphasic P wave polarity in lead aVL had a sensitivity of 71%, specificity of 82%, PPV of 80%, and NPV of 74% in predicting an arrhythmogenic focus of AF from SVC.
Conclusion: P wave polarity in leads V1 and aVL may predict an arrhythmogenic focus of AF from SVC or RSPV. (J Cardiovasc Electrophysiol, Vol. 14, pp. 350‐357, April 2003)
Additional Gene Variants Reduce Effectiveness of Beta‐Blockers in the LQT1 Form of Long QT Syndrome
Authors: KOBORI ATSUSHI , SARAI NOBUAKI , SHIMIZU WATARU , NAKAMURA YOSHIHIDE , MURAKAMI YOSUKE , MAKIYAMA TAKERU , OHNO SEIKO , TAKENAKA KOTOE , NINOMIYA TOMONORI , FUJIWARA YUICHIRO , MATSUOKA SATOSHI , TAKANO MAKOTO , NOMA AKINORI , KITA TORU , HORIE MINORU 
Published: December 2004

Introduction: Beta‐blockers are widely used to prevent the lethal cardiac events associated with the long QT syndrome (LQTS), especially in KCNQ1‐related LQTS (LQT1) patients. Some LQT1 patients, however, are refractory to this therapy. Methods and Results: Eighteen symptomatic LQTS patients (12 families) were genetically diagnosed as having heterozygous KCNQ1 variants and received beta‐blocker therapy. Cardiac events recurred in 4 members (3 families) despite continued therapy during mean follow‐up of 70 months. Three of these patients (2 families) had the same mutation [A341V (KCNQ1)]; and the other had R243H (KCNQ1). The latter patient took aprindine, which seemed to be responsible for the event. By functional assay using a heterologous mammalian expression system, we found that A341V (KCNQ1) is a loss‐of‐function type mutation (not dominant negative). Further genetic screening revealed that one A341V (KCNQ1) family cosegregated with S706C (KCNH2) and another with G144S (KCNJ2). Functional assay of the S706C (KCNH2) mutation was found to reduce the current density of expressed heterozygous KCNH2 channels with a positive shift (+8 mV) of the activation curve. Action potential simulation study was conducted based on the KYOTO model to estimate the influence of additional gene modifiers. In both models mimicking LQT1 plus 2 and LQT1 plus 7, the incidence of early afterdepolarization was increased compared with the LQT1 model under the setting of beta‐adrenergic stimulation. Conclusion: Multiple mutations in different LQTS‐related genes may modify clinical characteristics. Expanded gene survey may be required in LQT1 patients who are resistant to beta‐blocker therapy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 190‐199, February 2004)
Relationship Between Connexins and Atrial Activation During Human Atrial Fibrillation
Authors: KANAGARATNAM PRAPA , CHERIAN ASHOK , STANBRIDGE REX D.L. , GLENVILLE BRIAN , SEVERS NICHOLAS J. , PETERS NICHOLAS S. 
Published: December 2004

Introduction: Gap junctional connexin proteins (connexin40 [Cx40], connexin43 [Cx43]) are a determinant of myocardial conduction and are implicated in the development of atrial fibrillation (AF). We hypothesized that atrial activation pattern during AF is related to connexin expression and that this relationship is altered by AF‐induced remodeling in the fibrillating atria of chronic AF. Methods and Results: Isochronal activation mapping was performed during cardiac surgery on the right atria of patients in chronic AF (n = 13) using an epicardial electrode array. The atrial activation pattern was categorized using a complexity score based on the number of propagating wavefronts of activation and by grouping atria into those capable of uniform planar activation (simple) and those that were not (complex). The activation pattern was correlated with the levels of Cx43 and Cx40 signal measured by immunoconfocal quantification of biopsies from the mapped region. We studied the impact of electrical remodeling by comparing these findings with the unremodeled atria of patients in sinus rhythm during pacing‐induced sustained AF (n = 17). In chronic AF, atria with complex activation had lower Cx40 signal than atria showing simple activation (0.013 ± 0.006 μm2/μm2 vs 0.027 ± 0.009 μm2/μm2, P < 0.02), with the relative connexin signal (Cx40/Cx40+Cx43) correlating with complexity score (P = 0.01, r =−0.74). This relationship did not occur in the unremodeled atria, and increased heterogeneity of distribution of Cx40 labeling in chronic AF was the only evidence of connexin remodeling that we detected in the overall group. Conclusion: The pattern of atrial activation is related to immunoconfocal connexin signal only in the fully remodeled atria of chronic AF. This suggests that intercellular coupling and pattern of atrial activation are interrelated, but only in conjunction with the remodeling of atrial electrophysiology that occurs in chronic AF. (J Cardiovasc Electrophysiol, Vol. 15, pp. 206‐213, February 2004)
Sinus Rhythm Electrogram Shape Measurements are Predictive of the Origins and Characteristics of Multiple Reentrant Ventricular Tachycardia Morphologies
Authors: CIACCIO EDWARD J. , COROMILAS JAMES , COSTEAS CONSTANTINOS A. , WIT ANDREW L. 
Published: December 2004

Introduction: During clinical electrophysiologic study, multiple clinical tachycardia morphologies often can be induced in the infarct border zone, and all morphologies must be targeted for ablation therapy to be successful. Analysis of sinus rhythm electrogram shape for localizing figure‐of‐eight reentrant circuits in cases of multiple morphologies is proposed. Methods and Results: Sinus rhythm activation maps were constructed from bipolar electrograms acquired at 196 to 312 sites in the epicardial border zone in 10 postinfarction canine hearts. In each heart, at least two distinct figure‐of‐eight reentrant ventricular tachycardia morphologies were inducible by premature electrical stimulation, as determined by activation maps of sustained tachycardias. Sinus rhythm maps were used to predict the location of the isthmus (central common pathway [CCP]), which is the protected region of the circuit bounded by arcs of block (mean accuracy 76.7 ± 4%). Although reentrant circuits differed, the positions of the entrance point of each CCP were common. The location of the line that would span the CCP at its narrowest width also was estimated (mean accuracy 91.3 ± 5%). Ablation at this line is expected to prevent reentry recurrence. In one test experiment, ablation prevented recurrence of both sustained reentrant tachycardia morphologies. Conclusion: Sinus rhythm electrogram analyses are useful for (1) localizing multiple reentrant circuits with differences in morphology that are inducible by premature stimulation in the infarct border zone, and (2) locating and orienting the position of a linear lesion for preventing recurrence of all morphologies with minimal damage to the heart.
Atrial Ultrastructural Changes During Experimental Atrial Tachycardia Depend on High Ventricular Rate
Authors: SCHOONDERWOERD BAS A. , AUSMA JANNIE , CRIJNS HARRY J.G.M. , VAN VELDHUISEN DIRK J. , BLAAUW ENGBERT H. , VAN GELDER ISABELLE C. 
Published: December 2004

Introduction: Atrial structural and electrophysiologic changes occur during atrial tachycardia. The role of high ventricular rate in these processes remains to be established. Methods and Results: Six goats were subjected to 4 weeks of rapid atrioventricular (AV) pacing at an atrial and ventricular rate of 240 beats/min, resulting in development of congestive heart failure. In another five goats, AV block was created. These goats then were subjected to 4 weeks of atrial pacing, also at 240 beats/min while the ventricular rate was kept low and regular at 80 beats/min (A‐paced). Pacing was interrupted only for measurement of atrial effective refractory period and right atrial diameter. The ultrastructure of both atria was examined by light and electron microscopy, including quantification of the percentage of atrial extracellular matrix (%ECM). A group of six goats served as controls. In the AV‐paced group, severe structural remodeling occurred in the atria, including severe loss of sarcomeres, glycogen accumulation, disruption of sarcoplasmic reticulum, and appearance of numerous small mitochondria and nuclei with homogeneously distributed chromatin. In contrast, structural changes were virtually absent in the atria of A‐paced goats. Only a redistribution of nuclear chromatin and the appearance of numerous mitochondria were observed. The ultrastructure was normal in control animals. The%ECM was increased in AV‐paced goats (29%) compared to A‐paced animals (18%) and controls (17%) (P < 0.05). Finally, right atrial diameter increased by 51% in AV‐paced goats but was unchanged in A‐paced goats (P < 0.05). In both experimental groups, atrial effective refractory period shortened during pacing. Conclusion: Structural remodeling during chronic atrial tachycardia is related to the concomitant presence of a high ventricular rate and hence the occurrence of congestive heart failure rather than a high atrial rate. Electrical remodeling can occur in the absence of significant structural changes.
Impact of Coronary Sinus Lead Position on Biventricular Pacing:
Authors: ROSSILLO ANTONIO , VERMA ATUL , SAAD EDUARDO B. , CORRADO ANDREA , GASPARINI GIANNI , MARROUCHE NASSIR F. , GOLSHAYAN ALI REZA , McCURDY RICHARD , BHARGAVA MANDEEP , KHAYKIN YAARIV , BURKHARDT J. DAVID , MARTIN DAVID O. , WILKOFF BRUCE L. , SALIBA WALID I. , SCHWEIKERT ROBERT A. , RAVIELE ANTONIO , NATALE ANDREA 
Published: December 2004

Introduction: Biventricular pacing is an established treatment for congestive heart failure. Whether the anatomic location of the coronary sinus (CS) lead affects outcomes is unknown. The aim of this study was to evaluate the clinical response and mortality in patients who had transvenous CS leads placed in different anatomic branches for biventricular pacing. Methods and Results: We evaluated 233 consecutive patients with New York Heart Association (NYHA) class III–IV heart failure and ejection fraction <35% who had successful placement of a transvenous left ventricular lead through a CS venous branch. Patients were divided into two groups based on anatomic lead position. Group 1 (n = 66) included leads in the anterior and anterolateral branches. Group 2 (n = 167) included leads in the lateral and posterolateral branches. Postimplant, functional capacity improved from an average 3.1 to 2.7 in group 1 (P = 0.001) and from 3.1 to 2.3 in group 2 (P = 0.001). Left ventricular ejection fraction (LVEF) measured by transthoracic echocardiography did not improve significantly in group 1 (pre‐LVEF 18%, post‐LVEF 20%; P = NS) but increased significantly from 19% to 27% in group 2 (P = 0.008). Despite the difference in ejection fraction response, the mortality in the two groups after a mean follow‐up of 546 days was similar (13.6% group 1 vs 17.9% group 2). Conclusion: Placement of the CS lead in the lateral and posterolateral branches is associated with significant improvement in functional capacity and greater improvement in left ventricular function compared with the anterior CS location. This improvement does not appear to influence mortality.
Adaptive Diastolic Interval Control of Cardiac Action Potential Duration Alternans
Authors: JORDAN PETER N. , CHRISTINI DAVID J. 
Published: December 2004

Introduction: Recent experimental and computational studies have shown that beat‐to‐beat alternation in action potential duration can trigger cardiac reentry, suggesting that such “alternans” is a mechanistic precursor to arrhythmias. Given such a link, termination of alternans may help prevent the onset of arrhythmias. To this end, recent efforts have shown that chaos control methods can modulate the timing of electrical stimulation to eliminate alternans. Methods and Results: We have developed an alternative control method founded entirely in cardiac electrophysiology (rather than borrowing techniques from the control of physical systems as with existing control techniques). Using computer simulations, we show that this method, which exploits the rate‐dependent behavior of cardiac tissue, can be used to control alternans (and higher‐order) rhythms, and is robust to drift and noise. When applied to individual model cells exhibiting alternans, the algorithm converges to the period‐1 rhythm over as wide, and in some cases a wider, range of feedback proportionality constant values relative to existing methods. Control success comparable to existing methods is achieved when the algorithm is applied to a simulated one‐dimensional Purkinje fiber exhibiting alternans. Conclusion: We have developed a method that adaptively controls the timing of electrical stimulation to rapidly eliminate action potential duration alternans in cardiac tissue. This control method may prove valuable in future arrhythmia prevention therapies.
Improved Localization of Right‐Sided Accessory Pathways with Microcatheter‐Assisted Right Coronary Artery Mapping in Children
Authors: SHAH MAULLY J. , JONES THOMAS K. , CECCHIN FRANK 
Published: December 2004

Introduction: Radiofrequency ablation of some right‐sided accessory pathways continues to be challenging. The purpose of this study was to evaluate the efficacy of introducing a multielectrode microcatheter in the right coronary artery to localize accessory pathways when conventional mapping was unsuccessful. Methods and Results: A retrospective study was conducted of all right‐sided accessory pathway radiofrequency ablation procedures in which a multielectrode microcatheter as a reference in the right coronary artery was used to assist mapping. Between January 1998 and January 2002, 10 patients (5 males) underwent mapping of 11 accessory pathways with this technique at mean age of 12.3 ± 3.8 years. Five patients had Ebstein's anomaly of the tricuspid valve. Accessory pathways were identified in the following locations: right anterior 3, right anterolateral 2, right lateral 1, right posterolateral 2, and right posterior 3. Mean procedure time was 285 ± 70.3 minutes, and fluoroscopy time was 68.7 ± 21 minutes. Average mapping duration prior to microcatheter insertion in the right coronary artery was 136 ± 40 minutes. After microcatheter placement in the right coronary artery, the time to successful ablation of accessory pathways was 38 ± 11 minutes. All 11 (100%) accessory pathways were successfully ablated. Conclusion: Mapping in the right coronary artery with a microcatheter is an effective method to improve localization and successful ablation of difficult right‐sided accessory pathways.
Contagion Phenomena in Financial Crises: Evidence from the Portuguese and Spanish Exchange Rate Crises in the Early 1990s
Authors: Abreu Margarida 
Published: December 2004

AbstractBased on the experience of the Portuguese and Spanish financial crises in the early 1990s, this paper suggests that the spillover of exchange rate crises may reveal a particular dimension of the financial contagion effect: the presumption of mimetic behaviour by monetary authorities.This paper analyses the evolution of the credibility of the Escudo and the Peseta. We set out to test the existence of a contagion effect: that is, in what way does the polarization of exchange rate expectations in a scenario of devaluation of one currency explain the building up of a similar scenario for the other currency? We also examine the transmission mechanisms of such a scenario.Our results suggest the existence of a one‐way contagion effect, of the Escudo by the Peseta. Speculative attacks against the Peseta necessarily give rise to speculative attacks against the Escudo, regardless of the evolution of the ‘fundamentals’ of the Escudo. In this case, the spillover of financial crises could be better understood by the anticipated mimetic behaviour of monetary authorities, rather than by the geographical proximity of the countries in question or by the identical performance of the economies of both.
The Party System in the European Parliament: Collusive or Competitive?
Authors: Hix Simon , Kreppel Amie , Noury Abdul 
Published: December 2004

AbstractThis article looks at the development of the two main features of the party system in the European Parliament (EP): the organization of the party groups, and the nature of competition between these groups. On the organizational side, we examine the foundation of the party groups in the Common Assembly and the evolution of party organization from the appointed to the elected Parliament. On the competition side, we focus on the main axis of competition: the relationship between the Party of European Socialists (PES) and the European People's Party (EPP). We develop a set of competition propositions about PES‐EPP collusion, and test these arguments in a statistical analysis of PES and EPP roll‐call voting since 1979. We conclude that, contrary to what might be expected, the party system in the EP has become more consolidated and more competitive as the powers of the EP have increased.