bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Analysis of Epicardial Atrial Electrograms of Electrically Induced Atrial Fibrillation in Man
Authors: HOEKSTRA BART P.T. , DIKS CEES G.H. , ALLESSIE MAURITS A. , De GOEDB JACOB 
Published: May 2007

Nonlinear Analysis of AF in Man. Introduction: We applied methods from the theory of nonlinear dynamics to characterize unipolar epicardial right atrial electrograms of electrically induced atrial fibrillation (AF) in man. Methods and Results: Electrograms were selected from a high‐density mapping study, which confirmed the existence of at least 3 different types of induced AF (types I, II, and III) in patients undergoing open chest surgery. We analyzed sets of 5 electrograms (4 sec, sampling frequency 1 kHz, resolution 8 bits) in 9 patients (AF type I, n = 3; type II, n = 3; type III, n = 3). The Grassberger‐Procaccia method was applied to estimate the correlation dimension and correlation entropy from the electrograms. In 2 patients (AF type I) some electrograms (2 of 5 and 3 of 5, respectively) showed scaling at normalized distances ranging from 0.2 to 0.5 in phase space. Correlation dimension D ranged from 1.8 to 3.2 and correlation entropy K from 2.2 to 3.8 nats/sec. The patients were ranked according to increasing coarse‐grained correlation dimension Dcg (range 3.7 to 7.9) and coarse‐grained correlation entropy Kcg (range 5.6 to 18.6 nats/sec). The method of surrogate data was applied to detect nonlinearity in the electrograms. Using the correlation integral as test statistic, it could be excluded that electrograms of type I AF have been generated by linear stochastic dynamics. Episodes of sinus rhythm (D ranging from 1.0 to 5.1 and K from 2.0 to 8.6 nats/sec) and induced atrial flutter (D ranging from 2.7 to 4.2 and K from 2.2 to 4.2 nats/sec) in 2 different patients showed features of low‐dimensional chaos. Conclusion: Nonlinear analysis discriminated between electrograms during electrically induced AF in humans. The results are consistent with a classification of AF into 3 types based on the spatiotemporal complexity of right atrial activation patterns.
Evidence for Electrical Organization During Ventricular Fibrillation in the Human Heart
Authors: CLAYTON RICHARD H. , MURRAY ALAN , CAMPBELL RONALD W.F. 
Published: May 2007

Electrical Organization During VF.Introduction: Ventricular fibrillation is a most dangerous cardiac arrhythmia that has received considerable attention, yet its pattern of electrical activation remains controversial. The aim of this study was to investigate the degree of organization during the clinical arrhythmia and to examine the phase relationship between deflections in independent ECG leads.Methods and Results: Ten recordings of ventricular fibrillation were examined. Each had been provoked during routine electrophysiological study. The mean duration of ventricular fibrillation was 21 seconds (range 11 to 34). Independent and approximately orthogonal ECG leads I, aVF, and V2were recorded to computer at a sampling rate of 250 Hz. The phase relationship of each ECG lead pair was measured from the lag of peaks in their cross‐correlation function (CCF). In 61% of The 1‐second ECG epochs analyzed, CCF peak lag changed by < 20 msec compared to The previous epoch. Thus, the overall phase relationship was stable most of the time. Changes in CCF peak lag tended to be either gradual or to punctuate periods of stability.Conclusions: This study provides evidence of organized myocardial activation during human ventricular fibrillation.
The Architecture of the Atrioventricular Conduction Axis in Dog Compared to Man:
Authors: YEN HO SIEW , KILPATRICK LUCIENNE , KANAI TAKAO , GERMROTH PATRICIA G. , THOMPSON ROBERT P , ANDERSON ROBERT H. 
Published: May 2007

AV Node in Dog and Man. Introduction Advances in treating patients with dual atrioventricular nodal pathways have called for a better understanding of the morphology of the approaches to the atrioventricular node. In this respect, it has recently been suggested that, in dog, anatomically discrete muscle bundles originating from the sinus node represent the substrate of the dual pathways recognized electrophysiologically in patients with atrioventricular nodal reentrant tachycardia. This concept is at odds with most anatomic studies of the human specialized atrioventricular juuctional area. In this study, therefore, we studied histologically the junctional area in dog hearts, comparing them with our own findings in human heart and the descriptions of the earliest investigators. Methods and Results: Five dog and six human hearts were prepared for histology and sectioned serially in different planes. Reconstructions were then made from each of three dog and two human hearts sectioned in orthogonal planes. Gross differences in the anatomy of the atrioveutricular junctional area and in the structure of the conduction system were obvious between dog and human hearts. The penetrating portion of the conduction axis was longer in the dog, being much more extensively embedded in the central fibrous body. The atrioventricular node, in both dog and man, was composed of a zone of transitional cells overlying a compact region. The zone of transitional cells in the dog was more extensive posteriorly than anteriorly. No bundles insulated anatomically by fibrous tissue were found either in the internodal atrial myocardium or in the approaches to the atrioventricular node. Our findings in both dog and man are comparable with the initial descriptions of the atrioventricular junctional area. Conclusion: Although the disposition of the conduction system in dog and man is basically similar, there are important differences which relate to the gross anatomy. The anatomic substrate for functional duality of the inputs to the atrioventricular node remains unclear, since our study confirms that the concept of insulated atrionodal tracts has no morphologic basis.
Effect of Isoproterenol on Accessory Pathways Without Overt Retrograde Conduction
Authors: LI HUAGUI G. , YEE RAYMOND , KLEIN GEORGE J. 
Published: May 2007

Effect of Isoproterenol on Accessory Pathways. Introduction: Absence of overt retrograde accessory pathway conduction may be related to low resting sympathetic tone in patients with apparent unidirectional anterogradely conducting accessory pathways (UACAP). Methods and Results: To test this hypothesis, we studied the effect of isoproterenol on accessory pathway function and tachycardia induction in 18 patients (12 men and 6 women, ages 34 ± 16 years [mean ± SD]) with UACAP. After baseline study in the drug‐free state, electrophysiologic testing was repeated during infusion of isoproterenol (0.5 to 1.5 μg/min, titrated to increase heart rate by 20%). Isoproterenol shortened the anterograde effective refractory period (398 ± 117 vs 305 ± 63 msec; P < 0.01; basic drive cycle length 600 msec) of the accessory pathway. However, retrograde accessory pathway conduction and atrioventricular reentrant tachycardia were exposed in only 3 (17%) patients by isoproterenol infusion. All 3 patients with retrograde accessory pathway revealed after isoproterenol had clinically documented tachycardia (supraventricular tachycardia in 2, atrial fibrillation in 1) during exercise, while none of the patients with persistent absence of retrograde accessory pathway conduction had this symptom. Conclusions: We conclude that absence of overt retrograde conduction over accessory pathways may be related to low resting sympathetic tone in some individuals. Restoration of retrograde conduction with isoproterenol is unusual and most likely to be observed in patients with clinically documented paroxysmal supraventricular tachycardia related to exercise.
Activation Time Determination by High‐Resolution Unipolar and Bipolar Extracellular Electrograms in the Canine Heart
Authors: NDREPEPA GJIN , CAREF EDWARD B. , YIN HONG , El‐SHERIF NABIL , RESTIVO MARK 
Published: May 2007

Activation Time Determination by High‐Resolution Electrograms. Introduction: To identify the optimal criteria for activation time (AT) determination of bipolar electrograms from normal hearts, a high‐resolution cross electrode array comprising 128 unipolar electrodes of 500‐μm spacing was used to record extracellular potentials from the left ventricular epicardium of 12 dog hearts. Methods and Results: Recordings were made during broad wavefront propagation (B wave) local elliptical wavefront propagation (E wave). Characteristics of 863 bipolar electrograms (1‐mm spacing) were constructed from unipolar data standardized for differences in polarity, then classified morphologically. Features for bipolar AT determination were compared to the time of the negative peak of the firrst temporal derivative of a unipolar electrogram situated mid‐way between the bipoles. During B wave, three distinct morphologies were observed: unipbasic (61%), biphasic (23%), and triphasic (16%). Peak voltage of uniphasic and triphasic signals was the best predictor of AT (error: 0.6 ± 0.6 msec and 0.6 ± 0.8 msec, respectively). During E wave, parallel orientation of the bipoles with respect to the direction of impulse propagation wavefront resulted in uniphasic signals (> 99%), while for perpendicular orientation of the bipoles, electrogram morphology was variable. For parallel orientation of the bipoles, peak negative voltage was the best predictor of AT for both longitudinal and transverse propagation, while for perpendicular bipole orientation, peak negative voltage was a less reliable predictor for propagation along both fiber axes. Increasing interpolar distance resulted in a degradation in AT accuracy for B wave (from 0.6 ± 0.6 msec at 1 mm to 1.1 ± 1.2 msec at 7 mm) and for E wave (from 0.4 ± 0.3 msec at 1 mm to 3.1 ± 2.9 msec at 7 mm). Conclusions: (1) The accuracy of bipolar electrograms is sensitive to wavefront direction, bipole orientation, and interpolar distance; (2) peak negative voltage of uniphasic and triphasic signals is a reliable predictor of AT, but only for B wave; (3) a maximum interpolar distance of 2 mm and bipole orientation parallel to the direction of the impulse wavefront are minimally required for accurate determination of AT during impulse propagation initiated near the recording electrodes; and (4) for impulses initiated near the recording site in normal tissue, a bipbasic or triphasic morphology almost certainly indicates that the bipolar electrode is oriented perpendicular to the wavefront direction, irrespective of fiber orientation.
The Effect of Flunarizine and Ryanodine on Acquired Torsades de Pointes Arrhythmias in the Intact Canine Heart
Authors: VERDUYN S. CORA , VOS MARC A. , GORGELS ANTON P. , van der ZANDE JOLANDA , LEUNISSEN JET D.M. , WELLENS HEIN J. 
Published: May 2007

Flunarizine and Ryanodine in Acquired TdP. Introduction: Ryanodine, a specific blocker of the Ca2+ release channel of the sarcoplasmic reticulum, and flunarizine, a[Ca2+], overload blocker, possess antiarrhythmic effects against delayed after depolarizations (DADs) and DAD‐dependent arrhythmias. In vitro controversy exists about their effect on early after depolarizations (EADs): no effect was reported on cesium‐induced EADs, while ryanodine did prevent EADs induced by isoproterenol. To study the possible role of intracellular Ca2+ overload in acquired EAD‐dependent torsades de pointes (TdP) arrhythmias, we tested the effects of flunarizine and ryanodine in our animal model of TdP. Methods and Results: Anaesthetized dogs with chronic AV block received d‐sotalol or almokalant followed by pacing. A subset of dogs with reproducible TdP (≥ 3 times) were selected to receive flunarizine (2 mg/kg per 2 min) or ryanodine (10 μg/kg per 10 min). After dsotalol, TdP was induced at a mean cycle length of the idioventricular rhythm (CL‐IVR) of 2070 ± 635 msec and a QT(U) interval of 535 ± 65 msec. Induction of TdP was prevented by flunarizine in all experiments (8/8): electrophysiologically this was associated with a decrease in CL‐IVR, QT(U), and QTc interval (390 ± 100 to 320 ± 45, P < 0.05). Ryanodine prevented TdP induction in 4 of 5 experiments and decreased the CL‐IVR, QT(U), and the QTc interval from 385 ± 75 to 320 ± 20 msec (P < 0.05). Both drugs also suppressed the almokalant‐induced EADs and related ectopic activity. This antiarrhythmic action corresponded with the inability to reinduce TdP by pacing. Conclusions: Blockade of the Ca2+ release channel of the sarcoplasmic reticulum by ryanodine or the reduction of [Ca2+] overload by flunarizine prevents induction of EAD‐dependent acquired TdP arrhythmias, suggesting a role for [Ca2+]i overload in acquired TdP.
Variants of Preexcitation—Specialized Atriofascicular Pathways, Nodofascicular Pathways, and Fasciculoventricuiar Pathways:
Authors: KOTTKAMP HANS , HINDRICKS GERHARD , SHENASA HOSSEIN , CHEN XU , WICHTER THOMAS , BORGGREFE MARTIN , BREITHARDT GUNTER 
Published: May 2007

Variants of Preexcitation. introduction: In the present report, the electrophysiiologic findings in patients with different types of variants of preeexcitwtion, i.e., atriofascicualr, nodofacicular, and fasciculoventricular fibers, and the results of radiofrequency catheter ablation using different target sites are described. Methods and Results: Twelve patients (mean age 36 ± 17 years) with variants of the preexcitation syndromes underwent electrophysiologic study and radiofrequency catheter ablation. The atrial origin of atriofascicular pathways remote from the normal AV node was assessed by application of late atrial extrastimuli that advanced (“reset”) the timing of the next QRS complex without anterograde penetration into the AV node. In patients with atriofacicular pathways, ablation of the accessory pathway or the retrograde fast AV node pathway was attempted. Ablation of the atriofascicular pathways was guided by a stimulus‐delta wave interval mapping in the first live patients and by recording of atriofascicular pathway activation potentials in the next five patients. A nodofascicular pathway was suggested if VA dissociation occurred during tachycardia and if atrial extrastimuli failed to reset the tachycardia without anterograde penetration into the AV node. A fasciculoventricular connection was suggested if the proximal insertion of the accessory pathway was found to arise from the His bundle or bundle branches. The PR interval was expected within normal limits during sinus rhythm and the QRS complex to he slightly prolonged with a discrete slurring of the R wave, suggesting a small delta wave. Ten of the 12 patients had evidence for atriofascicular pathways and one patient each for a nodofascicular and fasciculoventricular pathway. In six patients, the atriofascicular pathways were successfully ablated, and in two patients, the retrograde fast AV node pathway. In one patient, a concealed right posteroseptal accessory AV pathway served as the retrograde limb and was successfully ablated. The nodofascicular pathway was shown to he a bystander during AV node reentrant tachycardia. After successful fast AV node pathway ablation resulting in marked PR prolongation, no preexcitation was present during sinus rhythm because of the proximal insertion of the nodofascicular pathway distal to the delay producing parts of the AV node. The proximal insertion of the fasciculoventricular pathway was suggested to arise distal to the AV node at the site of the penetrating AV bundle. The earliest ventricular activation at the His‐bundle recording site indicated the ventricular insertion of this accessory connection into the ventricular summit. The fasciculoventricular connection gave rise to a fixed ventricular preexcitation and served as a bystander during orthodromic AV reentrant tachycardia incorporating a left‐sided accessory AV pathway.
Electrocardiographic Patterns and Results of Radiofrequency Catheter Ablation of Clockwise Type I Atrial Flutter
Authors: SAOUDI NADIR , NAIR MOHAN , ABDELAZZIZ AHMED , POTY HERVE , DAOU ABDOU , ANSELME FREDERIC , LETAC BRICE 
Published: May 2007

Clockwise Rotation of Atrial Flutter. Introduction: Counterclockwise right atrial propagation is usually observed in common atrial flutter, but little is known regarding flutter with clockwise right atrial rotation. The aim of this study is to describe the ECG characteristics and results of catheter ablation of atrial flutter with clockwise right atrial rotation. Methods and Results: Among the 38 patients with type I atrial flutter in this study population, right atrial impulse propagation was counterclockwise in 20 and clockwise in 8. In the remaining 10 patients, both clockwise and counterclockwise patterns were seen. Clinical and ECG parameters associated with clockwise flutter were compared to those of 28 cases of counterclockwise atrial flutter. Ablation was performed in 11 of 18 cases using a technique identical to that used for counterclockwise flutter. A classical “sawtooth” pattern of the flutter wave was observed in 28 of 28 counterclockwise and 14 of 18 clockwise flutter. A shorter plateau phase, a widening of the negative component of the F wave in the inferior leads, and a negative F wave in V1 were the most consistent findings in clockwise flutter. Coronary sinus recording always showed septal to lateral left atrial impulse propagation. Ablation was successful in 11 of 11 cases of clockwise flutter in whom this procedure was performed, with 9.5 ± 11.6 radiofrequency pulses delivered between the tricuspid valve and the coronary sinus ostium (n = 5) or the inferior vena cava (n = 5), and in the proximal coronary sinus (n = 1). After a follow‐up of 46.6 weeks, two recurrences of clockwise flutter were encountered, which were successfully treated with a second session. Conclusion: Contrary to commonly accepted concepts, clockwise rotation of atrial flutter Ls not an infrequent phenomenon and can mimic counterclockwise rotation. It can also be successfully ablated by radiofrequency pulses.
Alternation of Atrioventricular Nodal Conduction Time During Atrioventricular Reentrant Tachycardia:
Authors: AMELLAL FARID , HALL KEVIN , GLASS LEON , BILLETTE JACQUES 
Published: May 2007

AV Nodal Conduction Time Alternation. Introduction: Alternation of atrial cycle length and AV nodal conduction time (NCT) is often observed during AV reentrant tachycardia. Both AV nodal dual pathway and rate‐dependent function have been postulated to be involved in this phenomenon. This study was designed to determine the respective role of these two mechanisms in the alternation observed in an in vitro model of orthodromic AV reentrant tachycardia. Methods and Results: The tachycardia was produced by detecting each His‐bundle activation and stimulating the atrium after a retrograde delay, thereby simulating retrograde pathway conduction, in six isolated rabbit heart preparations. After a 5‐minute stabilization period at a fast rate, the retrograde delay was decremented by 2 msec every minute until nodal blocks occurred. We observed a sequential alternation of the cycle length and NCT in four preparations in the short retrograde delay range. The magnitude of the alternation gradually increased as the retrograde delay was decreased and reached 4.6 ± 0.5 msec during 1:1 conduction. The alternation increased further just prior to termination of the tachycardia by an AV nodal block. None of the preparations showed discontinuous AV nodal recovery curves. Moreover, an electrode positioned over the endocardial surface of the node showed that the alternation developed distally to the nodal inputs, which are believed to constitute a major component of dual pathways. A mathematical model predicted the alternation from known characteristics of rate‐dependent nodal functional properties. Conclusions: NCT and cycle length alternation can arise during orthodromic AV reentrant tachycardia when the retrograde delay is sufficiently short. The characteristics of the alternation, presence of continuous recovery curves, intranodal location of the alternation, and mathematical modeling suggest that the alternation is predictahle from the known functional properties of the AV node without postulating dual pathway physiology.
Dimension and Related Anatomical Distance of Koch's Triangle in Patients with Atrioventricular Nodal Reentrant Tachycardia
Authors: UENG KWO‐CHANG , CHEN SHIH‐ANN , CHIANG CHERN‐EN , TAI CHING‐TAI , LEE SHIH‐HUANG , CHIOU CHUEN‐WONG , WEN ZU‐CHI , TSENG CHI‐JEN , CHEN YI‐JEN , YU WEN‐CHUNG , CHEN CHUNG‐YIN , CHANG MAU‐SONG 
Published: May 2007

Koch's Triangle in AVNRT. Introduction: The dimension of Koch's triangle in patients with AV nodal reentrant tachycardia has not been well described. Understanding the dimension and anatomical distance related to Koch's triangle might be useful in avoiding accidental AV block during ablation of the slow pathway. The purposes of this study were to define the dimension of Koch's triangle and its related anatomical distance and correlate these parameters with the successful ablation sites in patients with AV nodal reentrant tachycardia. Methods and Results: We studied 218 patients with AV nodal reentrant tachycardia. The distance between the presumed proximal His‐bundle area and the base of the coronary sinus orifice (DHis‐Os) measured in the right anterior oblique view was used to define the dimension of Koch's triangle. The distance of the proximal His‐bundle recording site from the successful ablation site (DHis‐Ab) and the distance as a fraction of the entire length of Koch's triangle (DHis‐Ab/DHis‐Os) were determined. The mean DHis‐Os, and DHis‐Ab were 25.9 ± 7.9 and 13.4 ± 3.8 mm, respectively. DHis‐os negatively correlated with patient age (r = ‐0.41, P < 0.0001) and body mass index (r = ‐0.18, P = 0.004). Among the patients with successful ablation sites in the medial area, DHis‐Os was longer (27.2 ± 6.6 vs 24.6 ± 8.4 mm, P < 0.005), DHis–Ab was similar (12.9 ± 3.1 vs 13.9 ± 4.0, P > 0.05) and DHis‐Ab/DHis‐Os was smaller (0.48 ± 0.04 vs 0.74 ± 0.11, P < 0.05). Furthermore, the patients with successful ablation sites in the medial location needed more radiofrequency pulse numbers than those in the posterior location (6 ± 4 vs 4 ± 3, P < 0.05). Conclusion: The site of successful slow pathway ablation was consistently about 13 mm from the site recording the proximal His‐bundle deflection in patients with AV nodal reentrant tachycardia despite marked variability in the dimensions of Koch's triangle: therefore, patients with large triangles required ablation in the medial region rather than the posterior region. Care should be taken when delivering radiofrequency energy to the posteroseptal area in patients with shorter DHis‐Os to avoid injury to AV node.