bluuebunny/crossref_metadata_2025_split huggingface dataset:
Critical Atrial Site for Ablation of Pacing‐Induced Atrial Fibrillation in the Normal Dog Heart
Authors: TONDO CLAUDIO , SCHERLAG BENJAMIN J. , OTOMO KENICHIRO , ANTZ MATTHIAS , PATTERSON EUGENE , ARRUDA MAURICIO , JACKMAN WARREN M. , LAZZARA RALPH 
Published: April 2007

Site for Ablation of AF in Dogs. Introduction: Radiofrequency catheter ablation (RFA) has been used recently to treat atrial fibrillation (AF). The purpose of this study was to investigate a new approach to preventing AF by RFA. Methods and Results: In open chest, anesthetized dogs, AF (lasting > 30 sec) was induced after burst stimulation, and electrophysiologic parameters were recorded before and after RFA. In group 1 (9 dogs) we performed selective and combined slow and fast pathway RFA, whereas in group 2(11 dogs) RFA was applied as a linear lesion at the mid‐atrial septum between the inferior vena cava and the fossa ovalis. After ablation, the Wenckebach cycle length was significantly prolonged only in group 1 (194 ± 23 vs 282 ± 35 msec, P = 0.002). whereas the interval between the stimulus (S) artifact applied at the high right atrium to the His hundle (H) (SH interval) prolonged to the same extent in both groups (162 ± 14 vs 146 ± 45 msec. P = NS); group 1 due to an A‐H prolongation whereas in group 2 it was due to an intra‐atrial conduction delay. In group 1 AF still remained inducible, although with a longer mean R‐R interval (215 ± 16 vs 433 ± 88 msec, P < 0.05). No instance of complete AV block developed. In group 2, sustained AF was noninducible in 10 dogs and its duration was markedly shorter in the remaining one (8 sec). Gross anatomy and histology did not reveal any damage inside of Koch's triangle, and particularly to the compact AV node. Conclusion: These findings suggest that RFA at the mid‐atrial septum prevents AF in the normal dog heart. This approach might also be successful in those clinical settings in which the atrial septum plays a critical role in the maintenance of sustained AF.
Three‐Dimensional Electromagnetic Catheter Technology:
Authors: KOTTKAMP HANS , HINDRICKS GERHARD , BREITHARDT GÜNTER , BORGGREFE MARTIN 
Published: April 2007

Electroanatomical Mapping. Introduction: The difficult catheter orientation and navigation associated with conventional technology and mono‐/multiplane fluoroscopy may complicate ablation procedures of atrial tachycardias. A new three‐dimensional catheter technology for electroanatomical mapping of the right atrium and ablation of ectopic atrial tachycardia is described. Methods and Results: A novel electromagnetic catheter‐based mapping system was investigated for electroanatomical mapping of the entire right atrium in 12 patients. The system reconstructed three‐dimensional maps from the multitude of endocardial sites that were sequentially mapped and color coded the individual activation times. The electrophysiologic information was superimposed on the geometry of the mapped area. The anatomical landmarks of the right atrium, i.e., the tricuspid annulus. mouth of the coronary sinus, ostia of the superior and inferior venae cavae, and right atrial appendage, could he depicted in all cases. The sinus node area and the preferential conduction along the crista terminalis could be delineated. In four patients with ectopic atrial tachycardia, the earliest endocardial activation could be identified with high spatial resolution as a “hot spot.” After completion of the mapping procedure, the ablation catheter could be reliably renavigated to the site of origin, and ablation was successful with one or two impulses. In one patient with previous atrial septal repair, the activation map allowed the reconstruction of a long line of conduction block induced by the atriotoniy. Conclusion: Three‐dimensional electroanatomical mapping of the right atrium allowed detailed reconstruction of the chamber geometry and activation sequence. The sites of origin of ectopic atrial tachycardias could be identified precisely. The system allowed accurate renavigation to the site of earliest activation, thereby guiding successful ablation of the foci.
Inappropriate Sinus Tachycardia After Radiofrequency Ablation of Para‐Hisian Accessory Pathways
Authors: PAPPONE CARLO , STABILE GIUSEPPE , ORETO GIUSEPPE , DE SIMONE ANTONIO , RILLO MARIANO , MAZZONE PATRIZIO , CAPPATO RICCARDO , CHIERCHIA SERGIO 
Published: April 2007

Inappropriate Sinus Tachycardia After Catheter Ablation. Introduction: Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinical significance of IST following RFA of para‐Hisian accessory pathways (APs). Methods and Results: Twenty‐eight patients (pts) with para‐Hisian APs underwent RFA. An AP was defined as para‐Hisian whenever its atrial and ventricular insertions were associated with a His‐bundle potential ≥ 0.1 mV. RF current was always delivered at the atrial aspect of the tricuspid annulus. to a site where the His‐bundle potential was < 0.15 mV. Time‐ and frequency‐domain analysis of heart rate variability was performed in 22 patients, before and after RFA. Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred. Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure. In 5 of them, IST disappeared spontaneously within 72 hours, whereas in 1 pt β‐blockers were required for 2 months. The atrial potential amplitude (1.217 ± 0.264 mV vs 0.882 ± 0.173 mV, P = 0.009) and A/V potential amplitude ratio (2.633 vs 1.686, P = 0.05) were significantly higher in pts who developed IST than in those who did not. A marked decrease in heart rate variability was observed only in pts who developed IST. Conclusion: IST is a relatively frequent complication after RFA of para‐Hisian APs: it is generally short‐lasting and usually does not require any treatment. IST after catheter ablation is likely to depend upon transient parasympathetic denervation of the sinus node.
Architecture of the Atrial Musculature In and Around the Triangle of Koch:
Authors: SANCHEZ‐QUINTANA DAMIAN , WYN DAVIES D. , YEN HO SIEW , OSLIZLOK PAUL , ANDERSON ROBERT H. 
Published: April 2007

Atrial Fibers. Introduction: Recent studies suggest that atrial fibers in the approaches to the AV node form part of the dual pathways recognized electrophysiologically in patients with AV nodal reentrant tachycardia (AVNRT). Our aim was to determine, by gross dissection, the arrangement of the superficial musculature in the area of the triangle of Koch In normal hearts and in hearts with documented AVNRT. hoping to ascertain anatomic features that might contribute to the debate. Methods and Results: We used blunt dissection to study the architecture of the superficial atrial musculature in 16 autopsied hearts from adults who died of noncardiac disease. A well‐defined pattern of architecture of muscle fibers was found in the region of the triangle of Koch, showing marked variations in 7 of the 16 specimens. The relationship of these fibers to the histologically specialized AV node was confirmed by histology in three cases. Two hearts from patients with known AVNRT, treated by ablation in one, were examined further histologically. These sections showed that the site of ablation was well distant from the histologically discrete AV node. Conclusion: The variability in the arrangement of the superficial atrial muscle fibers in the area of the triangle of Koch may be one of the factors influencing the route for impulses entering the AV node. Lesions that ablate nodal reentry are within these atrial fibers rather than the histologically specialized AV node.
Low‐Energy Transvenous Cardioversion of Atrial Fibrillation Using a Single Atrial Lead System
Authors: HEISEL ARMIN , JUNG JENS , NEUZNER JORG , MICHEL ULI , PITSCHNER HEINZ 
Published: April 2007

Atrial Cardioversion Using a Single Atrial Lead System. Introduction: Clinical studies have shown that electrical conversion of atrial fibrillation (AF) is feasible with transvenous catheter electrodes at low energies. We developed a single atrial lead system that allows atrial pacing, sensing, and defibrillation to improve and facilitate this new therapeutic option.Methods and Results: The lead consists of a tripolar sensing, pacing, and defibrillation system. Two defibrillation coil electrodes are positioned on a stylet‐guided lead. A ring electrode located between the two coils serves as the cathode for atrial sensing and pacing. We used this lead to cardiovert patients with acute or chronic AE. The distal coil was positioned in the coronary sinus, and the proximal coil and the ring electrode in the right atrium. R wave synchronized biphasic shocks were delivered between the two coils. Atrial signal detection and pacing were performed using the proximal coil and the ring electrode. Eight patients with acute AF (38 ± 9 min) and eight patients with chronic AF (6.6 ± 5 months) were included. The fluoroscopy time for lead placement was 3.5 ± 4.3 minutes. The atrial defibrillation threshold was 2.0 ± 1.4 J for patients with acute AE and 9.2 ± 5.9 J for patients with chronic AF (P < 0.01). The signal amplitude detected was 1.7 ± 1.1 mV during AF and 4.0 ± 2.9 mV after restoration of sinus rhythm (P < 0.001). Atrial pacing was feasible at a threshold of 4.4 ± 3.3 V (0.5‐msec pulse width).Conclusions: Atrial signal detection, atrial pacing, and low‐energy atrial defibrillation using this single atrial lead system is feasible in various clinical settings. Tbis system might lead to a simpler, less invasive approach for internal atrial cardioversion.
QT and JT Dispersion in Children with Long QT Syndrome
Authors: SHAH MAULLY J. , WIEAND TAMMY S. , RHODES LARRY A. , BERUL CHARLES I. , VETTER VICTORIA L. 
Published: April 2007

QT and JT Dispersion in Long QT Syndrome. Introduction: Abnormalities of ventricular repolarization leading to ventricular arrhythmias place children with long QT syndrome at high risk for sudden death. Dispersion of the QT (QTd) and JT (JTd) intervals, as markers of cardiac electrical heterogeneity, may be helpful in evaluating children with long QT syndrome and identifying a subset of patients at high risk for development of critical ventricular arrhythmias (ventricular tachycardia, torsades de pointes, and/or cardiac arrest).Methods and Results: The QTd and JTd intervals in 39 children with long QT syndrome were compared to those of 50 normal age‐matched children. In the long QT syndrome group, QTd measured 81 ± 70 msec compared to 28 ± 14 msec in the control group (P < 0.05), and JTd in the long QT syndrome group was 80 ± 69 msec compared to 25 ± 15 msec in the control group (P < 0.05).Conclusion: Children with long QT syndrome have an increased QTd and JTd when compared to normal controls. A QTd or JTd ≥ 55 msec correlates with the presence of critical ventricular arrhythmias. These ECG measures of dispersion can be useful in stratifying children with the long QT syndrome who are at higher risk for developing critical ventricular arrhythmias.
Optimized First Phase Tilt in “Parallel‐Series” Biphasic Waveform
Authors: YAMANOUCHI YOSHIO , MOWREY KENT A. , KROLL MARK W. , BREWER JAMES E. , DONOHOO ANN M. , WILKOFF BRUCE L. , TCHOU PATRICK J. 
Published: April 2007

“Parallel‐Series” Biphasic Waveform. Introduction: A biphasic defibrillation waveform can achieve a large second phase leading‐edge voltage by a “parallel‐series” switching system. Recently, such a system using two 30‐μF capacitances demonstrated better defibrillation threshold than standard waveforms available in current implantable devices. However, the optimized tilt of such a “parallel‐series” system had not been defined.Methods and Results: Defibrillation thresholds were evaluated for five different biphasic “parallel‐series” waveforms (60/15 μF) and a biphasic “parallel‐parallel” waveform (60/60 μF) in 12 anesthetized pigs. The five “parallel‐series” waveforms had first phase tilts of 40%, 50%, 60%, 70%, and 80% with second phase pulse width of 3 msec. The “parallel‐parallel” waveform had first phase tilt of 50% with second phase pulse width of 3 msec. The defibrillation lead system comprised a left pectoral “hot can” electrode (cathode) and a right ventricular lead (anode). The stored energy at defibrillation threshold of the “parallel‐series” waveform with first phase tilts of 40%, 50%, 60%, 70%, and 80% was 7.0 ± 2.1, 6.1 ± 2.8, 6.8 ± 2.8, 7.2 ± 2.9. and 8.4 ± 3.1 J, respectively. The stored energy of the “parallel‐series” waveform with a 50% first phase tilt was 16% less than the nonswitching “parallel‐parallel” waveform (7.3 ± 2.8 J, P = 0.006).Conclusions: A first phase tilt of 50% maximized defibrillation efficacy of biphasic waveforms implemented with a “parallel‐series” switching system. This optimized “parallel‐series” waveform was more efficient than the comparable “parallel‐parallel” biphasic waveform having the same first phase capacitance and tilt.
Electrophysiologic Effects of Interactions Between Activated Canine Neutrophils and Cardiac Myocytes
Authors: HOFFMAN BRIAN F. , FEINMARK STEVEN J. , GUO SHI‐DUO 
Published: April 2007

Effects of Neutrophils on Cardiac Myocytes. Introduction: Myocardial ischemia causes neutrophils to bind to activaled myocytes and liberate platelet‐activating factor (PAF). PAF causes delayed repolarization, early afterdepolarizations (EADs), and arrest of repolarization. We studied the effect of activation of neutrophils bound to canine cardiac myocytes to determine if such activation causes PAF generation and similar changes in transmembrane potentials.Methods and Results: Myocytes from canine left ventricle and neutrophils from the same dog were superfused with Tyrode's solution and transmembrane potentials recorded from the former. Neutrophils (100 μL, 10‐6/mL) were added and allowed to bind to the myocytes. Neutrophils were activated with 1% zymosan‐activated serum (ZAS). CV‐6209 (100 nM) was used to block receptors for PAF. Liberation of PAF by activated neutrophils was quantified with a commercial radioimmunoassay kit. Neutrophils activated with ZAS caused changes in myocyte transmembrane potentials like those induced by PAF: action potential prolongation, runs of EAD, and periods of plateau arrest. PAF receptor blockade prevented neutrophil activation from altering transmembrane potentials. Neutrophils activated with 1 % ZAS liberated significant amounts of PAF.Conclusions: When neutrophils bound to cardiac myocytes are activated by exposure to 1% ZAS, they cause prompt and consistent changes in myocyte electrical activity that could be arrhythmogenic for the in situ heart. These changes are similar to those caused by PAF in pharmacologic studies. Neutrophils activated in this manner generate PAF, and the effects of their activation are prevented by blockade of PAF receptors. We conclude that, during reperfusion of ischemic myocardium, PAF generated by activated neutrophils most likely is a cause of some arrhythmias.
Bundle Branch Reentry Ventricular Tachycardia with Two Distinct Left Bundle Branch Block Morphologies
Authors: WANG CHAO‐WEN , STERBA RICHARD , TCHOU PATRICK 
Published: April 2007

Bundle Branch Reentry VT with Two Morphologies. Introduction: Bundle branch reentry ventricular tachycardia (VT) is usually amenable to treatment with radiofrequency ablation. Different QRS morphologies during VT are possible when anterograde ventricular activation is over the left bundle branch. Manifestations of tbis reentrant tachycardia with more than one QRS morphology with anterograde activation via the right bundle have not been reported and would be unusual due to the more discrete anatomy of the right bundle branch.Methods and Results: An electropbysiologic study was conducted in a patient with dilated ventricle and diminished ventricular function with VT, Typical characteristics of bundle branch reentry were noted when VT was induced. The study was notable for the presence of a right bundle recording only during macroreentrant beats or VT and the distal location of the recording. Radiofrequency ablation was performed. Postablation stimulation again induced VT, proven to be of the same bundle branch reentry mechanism but of a different QRS morphology. A second ablation was required for complete ablation of this patient's bundle branch reentry VT.Conclusion: In bundle branch reentry utilizing the left bundle as the retrograde limb and the right bundle branch as the anterograde limb of the circuit, VT of more than one distinct morphology can be seen. Careful evaluation to assess for the persistence of VT of the same mechanism is necessary to ensure complete ablation of the reentrant circuit. Preexisting right bundle disease and a dilated heart with more dispersed distal right bundle branches may predispose to such a phenomenon.
Pretreatment with Antithrombotic Agents During Radiofrequency Catheter Ablation: A Randomized Comparison of Aspirin Versus Ticlopidine
Authors: MANOLIS ANTONIS S. , MAOUNIS THEMOS , VASSILIKOS VASSILIS , MELITA‐MANOLIS HELEN , PSARROS LEFTERIS , TERZOGLOU GEORGE , COKKINOS DENNIS V. 
Published: April 2007

Aspirin Versus Ticlopidine in Radiofrequency Ablation. introduction: D‐dimer is a product of fibrin degradation and can serve as a biochemical marker of thrombus formation and reactive fibrinolysis. According to our previous observations, and as reflected by elevated plasma D‐dimer levels, lesions produced by radiofrequency (RF) ablation have a thrombogenic effect, Pretreatment with combined aspirin and ticlopidine mitigates this thrombogenicity; however, the effect of either agent alone remains unknown. Methods and Results: In this study, 59 patients undergoing RF ablation were randomized to pretreatment with aspirin (group I; n = 30) or ticlopidine (group II; n = 29) for 3 days prior to RF ablation. D‐dimer levels were measured by enzyme immunoassay before and after the electrophysiologic study (EPS), and both immediately and at 48 hours after RF ablation. Results also were compared with those of 31 patients (nonrandomized group III) who bad received both aspirin and ticlopidine. At all stages, D‐dimer levels were higher in groups I and II when compared with group III. Baseline D‐dimer (31 ± 20 vs 24 ± 13 vs 17 ± 11 Mg/L, respectively; P= 0.002) rose after EPS to higher levels in groups I and II (91 ± 100 Mg/L and 51 ± 35 μg/L) compared with group III (31 ± 17 μg/L; P= 0.001). After RF ablation, D‐dimer levels increased in all groups, but this increase was much higher in groups I and II (214 ± 210 μg/L and 201 ± 222 μg/L) than in group III (74 ± 60 μg/L; P= 0.005). At 48 hours, D‐dimer levels decreased in all groups, but remained higher in groups I and II (91 ± 100 μg/L and 95 ± 99 μg/L) than in group III (35 ± 31 μg/L; P= 0.009). There were no differences among the three groups in the number of RF ablation lesions or the duration of the RF ablation procedure. Conclusion: Pretreatment with aspirin or ticlopidine alone does not decrease the thrombogenic potential of RF ablation. Only combined therapy with aspirin and ticlopidine has a favorable effect, as reflected by the lower degree of D‐dimer elevation.
Does Radiofrequency Ablation Induce a Prethrombotic State? Analysis of Coagulation System Activation and Comparison to Electrophysiologic Study
Authors: DORBALA SHARMILA , COHEN ALICE J. , HUTCHINSON LEIGH A. , MENCHAVEZ‐TAN EDITH , STEINBERG JONATHAN S. 
Published: April 2007

Ablation and Coagulation Activation. Introduction: Although thromboembolism is an uncommon complication of radiofrequency (RF) ablation, some preliminary reports have suggested that RF ablation results in activation of the coagulation system, possibly increasing this risk. We hypothesized that the insertion of intravenous catheters and their prolonged intravenous placement rather than RF ablation activates the coagulation cascade. Methods and Results: Thirty‐seven patients, group 1 (n = 21) during RF ablation, and group 2 (n = 16) during routine electrophysiologic studies (EPS), were studied prospectively. Blood was drawn for coagulation and fibrinolytic studies following insertion of venous sheaths (TO), following catheter placement (T1), and 1 hour after completion of RF ablation or EPS {T2). Conversion of prothrombin to thrombin was measured using thrombin‐antithrombin complex (TAT) and prothrombin activation peptide (F1+2). and fibrinolytic activity was assessed using D‐dlmer concentration. Levels of D‐dimer increased in group 1 from 823.52 ± 323.52 ng/mL at TO to 1,314.28 ± 297.63 ng/mL at T2 (P= 0.005), and in group 2 from 658.15 ± 161.70 ng/mL at T0 to 1625 641.45 ng/mL at T2 (P=±0.064). TAT levels increased from to 27.74 ± 5.6 μg/L at T0 to 52.99 ± 5.93 μg/L at T2 in group 1 (P= 0.09), and from 19.79 ± 5.14 μg/L at T0 to 73.5 ± 24.15 μg/L at T2 in group 2 (P= 0.05). F1+2 concentration increased from 1.52 ± 0.30 nmol/L at T0 to 3.06 ± 0.41 nmol/L at T2 in group 1 (P= 0.004), and from 1.32 ± 0.30 nmol/L at T0 to 3.11 ± 0.46 nmol/L at T2 in group 2 (P= 0.087). There was no significant difference in the concentration of the three coagulation variables between group 1 and group 2 at any given time point. No correlation was demonstrable between concentration of D‐dimers, TAT, or F1+2 and variables of RF delivery such as cumulative energy, number of RF energy applications, or number of impedance rises. However, a significant positive correlation (r = 0.65, P < 0.01) was noted between the duration of the RF ablation procedure and the concentration of D‐dimers. Conclusion: We conclude that activation of the coagulation cascade in RF ablation procedures is not related to the delivery of RF energy, but is related to the placement of intravascular catheters and to the duration of the ablation procedure.
Atrial Electrograms and Activation Sequences in the Transition Between Atrial Fibrillation and Atrial Flutter
Authors: EMORI TETSURO , FUKUSHIMA KENGO , SAITO HIRONORI , NAKAYAMA KAZUAKT , OHE TOHRU 
Published: April 2007

Transition Between Atrial Fibrillation and Flutter. Introduction: The eletrophysiologic mechanism of atrial fibrillation (AF) has a wide spectrum, and it seems that some atrial regions are essential for the occurrence of a particular type of AF. We focused on one type of AF: AF associated with typical atrial flutter (AFI), which was right atrial (RA) arrhythmia, and sought to investigate intra‐atrial electrograms and activation sequences in the transition between AF and AFL. Methods and Results: Intra‐atrial electrograms and activation sequences in the R.A free wall and the septum were evaluated in the transition between AF and AFL in seven patients without organic heart disease (all men; mean age 57 ± 11 years). In five episodes of the conversion of AFL into AF, the AFL cycle length was shortened (from 211 ± 6 msec in stable AFL to 190 ± 15 msec before the conversion, P, 0.001). Interruption of the AFL wavefront and an abrupt activation sequential change induced by a premature atrial impulse resulted in fractionation and disorganization of the septal electrograms. During sustained AF, septal electrograms were persistently fractionated with disorganized activation sequences. However, the RA free‐wall electrograms were organized, and the activation sequence was predominantly craniocaudal rather than caudocranial throughout AF. In 12 episodes of the conversion of AF into AFL, the AF cycle length measured in the RA free wall increased (from 165 ± 26 msec at the onset of AF to 180 ± 24 msec before the conversion, P, 0.001). AFL resumed when fractionated septal electrograms were separated and organized to the caudocranial direction, despite the RA free‐wall electrograms remaining discrete and sharp with an isoelectric line. Conclusion: Changes of the electrogram and activation sequence in the atrial septum played an important role in the transition between AF and AFL.