bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased Levels of Tissue Plasminogen Activator Antigen and Factor VIII Activity in Nonvalvular Atrial Fibrillation: Relation to Predictors of Thromboembolism
Authors: WANG TZUNG‐DAU , CHEN WEN‐JONE , SU SOPHIA SEH‐YI , SU TA‐CHEN , CHEN MING‐FONG , LIAU CHIAU‐SUONG , LEE YUAN‐TEH 
Published: August 2003

Atrial Fibrillation and Hypercoagulability.
Introduction: Given that nonvalvular atrial fibrillation (AF)‐associated stroke can be either cardioembolic or atherothrombotic, we investigated the relationships between nonvalvular AF and hemostatic factors reflecting intrinsic thrombogenic and atherogenic potentials (tissue plasminogen activator [t‐PA] antigen, plasminogen activator inhibitor‐1, and factor VIII activity). We also evaluated the clinical applicability of these hemostatic factors by examining whether AF subjects with established clinical or echocardiographic predictors of thromboembolism had higher levels of these factors. Methods and Results: Of the 3,212 participants of a Chinese population‐based study, 53 subjects (1.7%) with AF were identified. Among the hemostatic factors measured, t‐PA antigen (median 12.8 vs 8.1 ng/mL; P < 0.01) and factor VIII activity (median 155% vs 133%; P < 0.05) were significantly higher in AF subjects after adjustment for age and sex. In multivariate analysis, features independently associated with t‐PA antigen levels were AF, age, sex, body mass index, systolic blood pressure, total cholesterol, triglycerides, and left ventricular systolic dysfunction. Features independently associated with factor VIII activity levels included AF, age, and total cholesterol. Levels of both t‐PA antigen and factor VIII activity were primarily elevated in AF subjects with predictors of thromboembolism (age > 75 years, hypertension, diabetes, and left ventricular systolic dysfunction), whereas in AF subjects with no thromboembolic predictors, plasma levels of hemostatic factors examined were similar to those without AF. Conclusion: We demonstrated that nonvalvular AF was independently associated with increased peripheral levels of t‐PA antigen and factor VIII activity. Levels of both hemostatic factors were primarily elevated in AF subjects with predictors of thromboembolism. Whether these hemostatic factors are independently predictive of future thromboembolic events in AF patients requires further investigation.
Acquired Pulmonary Vein Stenosis after Radiofrequency Catheter Ablation of Paroxysmal Atrial Fibrillation
Authors: YU WEN‐CHUNG , HSU TSUI‐LIEH , TAI CHING‐TAI , TSAI CHIN‐FENG , HSIEH MING‐HSIUNG , LIN WEI‐SHIANG , LIN YUNG‐KUO , TSAO HSUAN‐MING , DING YU‐AN , CHANG MAU‐SONG , CHEN SHIH‐ANN 
Published: August 2003

PV Stenosis after AF Ablation.
Introduction: Elimination of the initiating focus within the pulmonary vein (PV) using radiofrequency (RF) catheter ablation is a new treatment modality for treatment of drug‐refractory atrial fibrillation. However, information on the long‐term safety of RF ablation within the PV is limited. Methods and Results: In 102 patients with drug‐refractory atrial fibrillation and at least one initiating focus from the PV, series transesophageal echocardiography was performed to monitor the effect of RF ablation on the PV. There were 66 foci in the right upper PV and 65 foci in the left upper PV. Within 3 days of ablation, 26 of the ablated right upper PVs (39%) had increased peak Doppler flow velocity (mean 130 ± 28 cm/sec, range 106 to 220), and 15 of the ablated left upper PVs (23%) had increased peak Doppler flow velocity (mean 140 ± 39 cm/sec, range 105 to 219). Seven patients had increased peak Doppler flow velocity in both upper PVs. No factor (including age, sex, site of ablation, number of RF pulses, pulse duration, and temperature) could predict PV stenosis after RF ablation. Three patients with stenosis of both upper PVs experienced mild dyspnea on exertion, but only one had mild increase of pulmonary pressure. There was no significant change of peak and mean flow velocity and of PV diameter in sequential follow‐up studies up to 16 (209 ± 94 days) months. Conclusion: Focal PV stenosis is observed frequently after RF catheter ablation applied within the vein, but usually is without clinical significance. However, ablation within multiple PVs might cause pulmonary hypertension and should be considered a limiting factor in this procedure.
Activation Patterns in the Left Atrium During Counterclockwise and Clockwise Atrial Flutter
Authors: NDREPEPA GJIN , ZRENNER BERNHARD , WEYERBROCK SONJA , SCHNEIDER MICHAEL A.E. , SCHMITT CLAUS 
Published: August 2003

Activation of the LA During Atrial Flutter.
Introduction: Activation of the left atrium (LA) in patients with isthmus‐dependent right atrial flutter (AFL) has not yet been studied. The aim of this study was to analyze the activation patterns in the LA in patients with counterclockwise and clockwise AFL. Methods and Results: The study population consisted of 12 patients (10 men and 2 women; mean age 61 ± 13 years) with documented AFL and atrial fibrillation referred for ablation. The LA was mapped with a 64‐electrode basket catheter inserted through a transseptal approach (10 patients) or an open foramen ovale (2 patients). In patients with counterclockwise AFL (10 episodes), the LA was activated for a mean of 133 ± 28 msec. Two endocardial breakthroughs of earliest activity on the left side of the interatrial septum, separated in time by an interval of 38 ± 15 msec, were observed in 9 episodes (90%). Two wavefronts originated from these breakthroughs, which activated the posterior and the anterior LA walls, respectively. In one patient, the entire LA was activated from the inferior breakthrough. In patients with clockwise AFL (five episodes), the LA activation time was 130 ± 13 msec. During ongoing episodes, two early electrical breakthroughs, separated in time by an interval of 41 ± 15 msec, appeared in the high anteroseptal and low posteroseptal LA regions. The superior wavefront that emerged from the high anterolateral LA region was the dominant activation pathway in 4 (80%) of 5 episodes. Conclusion: In patients with AFL, the LA is activated by two wavefronts originating from the high anterior and the low posterior regions of the interatrial septum. The sequence of activation of these interatrial connections in counterclockwise or clockwise AFL and the conductive properties of the LA conduction pathways determine the activation patterns in the LA.
Clinical Outcome after Radiofrequency Catheter Ablation of Focal Atrial Fibrillation Triggers
Authors: GERSTENFELD EDWARD P. , GUERRA PETER , SPARKS PAUL B. , HATTORI KYOKO , LESH MICHAEL D. 
Published: August 2003

Ablation of Focal Atrial Fibrillation.
Introduction: Ablative therapy for atrial fibrillation (AF) by targeting initiating triggers, usually in or around the pulmonary veins, has been reported by several centers. Evidence for an overall improvement in quality of life (QOL) and amelioration of symptoms is lacking. Methods and Results: Seventy‐one patients undergoing attempted ablation of focal AF were followed for 60 ± 33 weeks. QOL and symptom questionnaires were completed 1 month before and 6 months after electrophysiologic study. Twenty‐three patients (32%) underwent electrophysiologic mapping but no ablation because of either insufficient or multifocal ectopy; the other 48 patients (68%) underwent attempted ablation. Sixteen of 48 patients (33%) undergoing ablation, or 16 (23%) of 71 on an intention to‐treat basis, were found at last follow‐up to have persistent sinus rhythm without antiarrhythmic drugs. Patients who underwent mapping without ablation reported no improvements in any QOL or symptom score, whereas patients who had long‐term successful ablation had significant improvements in all six QOL measures. Interestingly, patients who developed AF recurrence after ablation still reported significant improvements in 4 of 6 QOL measures. Four of 48 patients (8.3%) undergoing ablation developed pulmonary vein stenosis. Conclusion: Paroxysmal AF can be treated successfully in some patients by ablating initiating triggers in the pulmonary veins; however, in our experience the recurrence rate (32/48 [68%]) and risk of pulmonary vein stenosis (8%) after ablation are high. Patients with recurrent AF after ablation of focal AF triggers have significant improvement in QOL and symptoms compared with before ablation. Patients and their physicians should carefully balance the risks and benefits before considering ablation.
Prevention of Chronic Atrial Fibrillation by Pacing in the Region of Bachmann's Bundle: Results of a Multicenter Randomized Trial
Authors: BAILIN STEVEN J. , ADLER STUART , GIUDICI MICHAEL 
Published: August 2003

Bachmann's Bundle Pacing for AF Prevention.
Introduction: Atrial pacing locations that decrease atrial activation and recovery time may be preferable in patients with a history of atrial arrhythmias. This multicenter prospective randomized study compared the efficacy of Bachmann's bundle (BB) region pacing to right atrial appendage (RAA) pacing in patients with recurrent paroxysmal atrial fibrillation (AF). Methods and Results: Patients with standard pacing indications (n = 120, 70 ± 11 years) were randomized to atrial pacing in either the RAA (n = 57) or BB region (n = 63). Implantation time was similar between groups (88 ± 36 min[n = 38] for BB vs 83 ± 34 min [n = 34] for RAA). No differences in pacing threshold, impedance, or sensing between BB and RAA groups were observed at implantation or after the 6‐week, 6‐month, and 1‐year follow‐up periods. Average length of follow‐up was 12.6 ± 7.4 months for the BB group and 11.8 ± 8.0 months for the RAA pacing group. The percentage of atrial pacing was similar between groups (61% ± 34% RAA vs 65% ± 31% BB at 2 weeks after implant). BB atrial pacing significantly (P < 0.05) shortened p wave duration compared with sinus rhythm (123 ± 21 msec vs 132 ± 21 msec, n = 50) 2 weeks after implant. In contrast, p wave duration was longer during atrial pacing from the RAA position compared with sinus rhythm (148 ± 23 msec vs 123 ± 23 msec, n = 37). Additionally, p wave duration was shorter during BB pacing than during RAA pacing. Patients with BB pacing had a higher (P < 0.05) rate of survival free from chronic AF (75%) compared with patients with RAA pacing (47%) at 1 year. Conclusion: BB region pacing is safe and effective for attenuating the progression of AF.
Defibrillation Efficacy Comparing a Subcutaneous Array Electrode versus an “Active Can” Implantable Cardioverter Defibrillator and a Subcutaneous Array Electrode in Addition to an “Active Can” Implantable Cardioverter Defibrillator: Results from Active Can versus Array Trials I and II
Authors: GRADAUS RAINER , BLOCK MICHAEL , SEIDL KARLHEINZ , BRUNN JÜRGEN , ISGRO FRANK , HAMMEL DIETER , HAUER BERND , BREITHARDT GÜNTER , BÖCKER DIRK 
Published: August 2003

Defibrillation Efficacy.
Introduction: Placement of implantable cardioverter defibrillators (ICDs) has been simplified by using the shell of a pectorally implanted ICD as a defibrillation electrode in combination with an endocardial right ventricular defibrillation lead. However, a sufficiently low defibrillation threshold (DFT) cannot be obtained in a few patients. Therefore, alternative approaches were systematically tested in the Active Can versus Array Trial (ACAT). Methods and Results: In the first of two prospective randomized studies, the DFT of a subcutaneous left dorsolateral array anode introduced from a pectoral incision was compared to that of a standard active can anode in 68 patients. Intraoperatively, the DFT was determined twice in each patient using either the active can or, in patients with a subcutaneous array lead, once with all three fingers and once omitting the middle finger of the array. The second prospective randomized study included 40 patients. DFT also was determined twice in each patient using an active can in a left pectoral position as anode alone and combined with a left dorsolateral array electrode with two fingers. In ACAT I, stored energy at DFT decreased from 13.1 ± 7.7 J (active can) to 9.6 ± 6.1 J (three‐finger array lead) (P = 0.04), impedance decreased from 53 ± 8 Ω to 40 ± 6 Ω (P < 0.0001). Omitting the middle finger of the array lead, stored energy at DFT increased by 0.9 J (P = 0.47) and impedance by 2 Ω (P < 0.0001). In ACAT II, DFT and impedance using an active can device were significantly lower when a two‐finger array lead was added that decreased stored energy at DFT from 10.1 ± 5.2 J to 6.9 ± 3.9 J (P = 0.001) and impedance from 56 ± 5 Ω to 42 ± 5 Ω (P < 0.0001). Conclusion: In combination with a right ventricular defibrillation electrode, a left pectoral subcutaneous array lead improves defibrillation efficacy if used instead of, or in addition to, a left pectoral active can ICD device. Implantation of the array lead can be simplified by using two instead of three fingers, without a significant loss of defibrillation efficacy.
Electrophysiologic Characteristics of Ventricular Extrastimulation‐Induced Dissipation of Functional Bundle Branch Block Associated with Supraventricular Tachycardia
Authors: WANG SHANE HAW , HAN JENNIFER , HOU CHARLES , SUNG RUEY J. 
Published: August 2003

Dissipation of Functional Bundle Branch Block.
Introduction: Linking‐related anterograde functional bundle branch block during supraventricular tachycardia (SVT) is due to repetitive concealed retrograde conduction of impulses from the contralateral bundle branch and can be eliminated by a critically timed premature ventricular beat (PVB). We assessed the electrophysiologic characteristics of PVB‐induced dissipation of functional bundle branch block during SVT. Methods and Results: During SVT with functional bundle branch block, PVB was delivered from the right ventricular apex, scanning the tachycardia cycle length (CL) with 10‐msec decrements in the coupling interval in 14 patients (3 AV nodal reentrant tachycardia and 11 orthodromic AV reciprocating tachycardia). Dissipation was achieved in group 1: functional right bundle branch block (RBBB) in 4, functional left bundle branch block (LBBB) in 4, and both functional RBBB and LBBB in 1 with a dissipation zone occupying 4% to 13% (mean 8.5%) of the tachycardia CL. The outer limits were 22 ± 16 msec and 68 ± 14 msec < tachycardia CL; the inner limits were 56 ± 18 msec and 90 ± 24 msec < tachycardia CL for RBBB and LBBB, respectively (both P < 0.05). Dissipation could not be achieved in group 2 (4 RBBB and 1 LBBB) due to CL‐dependent bundle branch block and/or local ventricular refractoriness. Conclusion: During SVT, functional bundle branch block due to “linking” often can be dissipated by timely PVB delivered from the right ventricular apex within a narrow zone of the tachycardia CL. Our findings suggest that the dissipation zone is affected by the pattern of functional bundle branch block relative to the site of PVB delivery.
Usefulness of Midodrine in Patients with Severely Symptomatic Neurocardiogenic Syncope: A Randomized Control Study
Authors: PEREZ‐LUGONES ALEJANDRO , SCHWEIKERT ROBERT , PAVIA STEPHEN , SRA JASBIR , AKHTAR MASOOD , JAEGER FREDRICK , TOMASSONI GERY F. , SALIBA WALID , LEONELLI FABIO M. , BASH DIANNA , BEHEIRY SALWA , SHEWCHIK JEANNE , TCHOU PATRICK J. , NATALE ANDREA 
Published: August 2003

Midodrine for Neurocardiogenic Syncope.
Introduction: The efficacy of midodrine for the management of patients with neurocardiogenic syncope was assessed prospectively in a randomized control study. Methods and Results: Patients who had at least monthly occurrences of syncope and a positive tilt‐table test were included in the study. A total of 61 patients were randomly allocated to treatment either with midodrine or with fluid, salt tablets, and counseling. Midodrine was given at a starting dose of 5 mg three times a day and increased up to a dose of 15 mg three times a day when required. Midodrine was given during the daytime every 6 hours. Thirty‐one patients were assigned to treatment with midodrine; the other 30 patients were advised to increase their fluid intake and were instructed to recognize their prodromes and abort the progression to syncope. Patients were followed‐up for at least 6 months. A quality‐of‐life questionnaire was administered at the time of randomization and 6 months after. At the 6‐month follow‐up, 25 (81%) of 31 midodrine‐treated patients and 4 (13%) of the 30 fluid‐therapy patients had remained asymptomatic (P < 0.001). One patient had to discontinue taking midodrine due to severe side effects and another six patients experienced minor side effects that did not require drug discontinuation. Conclusion: Midodrine appeared to provide a significant benefit in patients with neurocardiogenic syncope. To prevent recurrence of symptoms, dose adjustments were required in about one third of patients.
Prolongation of Activation‐Recovery Interval over a Preexcited Region before and after Catheter Ablation in Patients with Wolff‐Parkinson‐White Syndrome
Authors: INDEN YASUYA , HIRAI MAKOTO , TAKADA YASUNOBU , SHIMIZU ATSUYA , SHIMOKATA KEIKO , YOSHIDA YUKIHIKO , AKAHOSHI MAKOTO , KONDO TAKAHISA , SAITO HIDEHIKO 
Published: August 2003

Activation‐Recovery Interval in WPW Syndrome.
Introduction: Preexisting changes in repolarization properties play an important role in T wave abnormalities (cardiac memory) after ablation in patients with Wolff‐Parkinson‐White (WPW) syndrome. However, no report has provided direct evidence for prolongation of action potential duration (APD) over a preexcited region before and after ablation. Methods and Results: We studied 10 patients with ventricular preexcitation due to a left‐sided accessory pathway (AP) (group M) and 12 patients with concealed left‐sided AP (group C) to clarify prolongation of APD using activation‐recovery intervals (ARIs) from epicardial and endocardial unipolar electrograms in patients with WPW syndrome. ARI was calculated from unipolar electrograms at the His bundle and the coronary sinus adjacent to the AP during atrial pacing (100 beats/min) before and 30 minutes after ablation. Before ablation, ARIs at the AP site were significantly longer in group M than in group C (255 ± 21 msec vs 211 ± 24 msec; P < 0.01), whereas ARIs at the His bundle did not differ between the two groups (255 ± 20 msec vs 245 ± 27 msec; P = NS). After ablation, group M showed no significant changes in ARIs at the AP and His bundle (256 ± 19 msec and 253 ± 15 msec) compared with before ablation. Conclusion: We found by direct analysis of ARIs from the epicardium that APD prolongation over the preexcited region was present before catheter ablation and persisted after catheter ablation. The gradual changes in repolarization properties, including APD prolongation after discontinuation of AP, may be one mechanism of cardiac memory after catheter ablation in patients with WPW syndrome.
Virtual Electrode Polarization Leads to Reentry in the Far Field
Authors: LINDBLOM ANNETTE E. , AGUEL FELIPE , TRAYANOVA NATALIA A. 
Published: August 2003

Virtual Electrode Polarization.
Introduction: Our previous article examined cardiac vulnerability to reentry in the near field within the framework of the virtual electrode polarization (VEP) concept. The present study extends this examination to the far field and compares its predictions to the critical point hypothesis. Methods and Results: We simulate the electrical behavior of a sheet of myocardium using a two‐dimensional bidomain model. The fiber field is extrapolated from a set of rabbit heart fiber directions obtained experimentally. An S1 stimulus is applied along the top or left border. An extracellular line electrode on the top delivers a cathodal or anodal S2 stimulus. A VEP pattern matching that seen experimentally is observed and covers the entire sheet, thus constituting a far‐field effect. Reentry arises from break excitation, make excitation, or a combination of both, and subsequent propagation through deexcited and recovered areas. Reentry occurs in cross‐field, parallel‐field, and uniform refractoriness protocols. For long coupling intervals (CIs) above CImakemin (defined as the shortest CI at which make excitation can take place), rotors move away from the cathodal electrode and the S1 site for increases in S2 strength and CI, respectively. For cathodal S2 stimuli, findings are consistent with the critical point hypothesis. For CIs below CImakemin, reentry is initiated by break excitation only, and the resulting reentrant patterns are no longer consistent with those predicted by the critical point hypothesis. Conclusion: Shock‐induced VEP can explain vulnerability in the far field. The VEP theory of vulnerability encompasses the critical point hypothesis for cathodal S2 shocks at long CIs.
Atrial Defibrillation Thresholds of Electrode Configurations Available to an Atrioventricular Defibrillator
Authors: BENSER MICHAEL E. , WALCOTT GREGORY P. , KILLINGSWORTH CHERYL R. , GIROUARD STEVEN D. , MORRIS MILTON M. , IDEKER RAYMOND E. 
Published: August 2003

Atrial Defibrillation Thresholds.
Introduction: Little investigation has been conducted to assess the atrial defibrillation thresholds of electrode configurations using electrodes designed for internal ventricular defibrillation (right ventricle [RV], superior vena cava [SVC], and pulse generator housing [Can]) combined with coronary sinus (CS) electrodes. We hypothesized that a CS → SVC+Can electrode configuration would have a lower atrial defibrillation threshold than a standard configuration for defibrillation, RV → SVC+Can. We also tested the atrial defibrillation thresholds of five other configurations. Methods and Results: In 12 closed chest sheep, we situated a two‐coil (RV, SVC) defibrillation catheter, a left‐pectoral subcutaneous Can, and a CS lead. Atrial fibrillation was burst induced and maintained with continuous infusion of intrapericardial acetyl‐β‐methylcholine chloride. Using fixed‐tilt biphasic shocks, we determined the atrial defibrillation thresholds of seven test configurations in random order according to a multiple‐reversal protocol. The peak voltage and delivered energy atrial defibrillation thresholds of CS → SVC+Can (168 ± 67 V, 2.68 ± 2.40 J) were significantly lower than those of RV → SVC+Can (215 ± 88 V, 4.46 ± 3.40 J). The atrial defibrillation thresholds of the other test configurations were RV+CS → SVC+Can 146 ± 59V, 1.92 ± 1.45 J; RV
→ CS+SVC+Can:191 ± 89V, 3.53 ± 3.19 J; CS → SVC: 188 ± 98V, 3.77 ± 4.14 J; SVC → CS+Can: 265 ± 145 V, 7.37 ± 9.12 J; and SVC → Can: 516 ± 209 V,
24.5 ± 15.0 J. Conclusions: The atrial defibrillation threshold of CS → RV SVC+Can. In addition, the low atrial defibrillation threshold of RV+CS → SVC+Can merits further investigation. Based on corroboration of low atrial defibrillation thresholds of CS‐based configurations in humans, physicians might consider using CS leads with atrioventricular defibrillators.