bluuebunny/crossref_metadata_2025_split huggingface dataset:
Association Between Atrial Fibrillation and Appropriate Implantable Cardioverter Defibrillator Therapy:Results from a Prospective Study
Authors: GRÖNEFELD GERIAN C. , MAUSS OLIVER , LI YI‐GANG , KLINGENHEBEN THOMAS , HOHNLOSER STEFAN H. 
Published: August 2003

Atrial Fibrillation and Appropriate ICD Therapy. Introduction: Atrial fibrillation(AF) is associated with significant morbidity and mortality that may be related to heniodynamic Impairment, thromboembolic events, or enhanced electrical instability of the ventricular myocardium. There is, however, a lack of data concerning the association of AF and ventricular tachyarrhythmias.Methods and Results: Consecutive patients with indication for an implantable cardioverter defibrillator (ICD) were classified for the presence or absence of persistent AF at the time of device implantation. Incidence of device therapy, stored electrograms, and clinical events during follow‐up were evaluated prospectively. Two hundred fifty patients were included. During follow‐up (20 ± 14 months), patients in AF experienced appropriate device therapy for recurrent ventricular arrhythmias more frequently compared with patients in sinus rhythm (SR) (63% vs 38%, P = 0.01). On multivariate analysis, AF was an independent predictor of appropriate ICD therapy (relative risk 1.8; 95% confidence interval [CI] 1.2 to 2.9) and in appropriate device therapy (relative risk 2,3; 95% CI 1,2 to 4.5). Predefined clinical events (cluster endpoint: death, syncope, and hospitalizations) were observed more frequently in AF than in SR patients (55% vs 31%. P = 0.01). Analysis of device‐stored electrograms revealed a higher incidence of short‐long‐short cycles preceding ventricular arrhythmias in AF compared with SR patients (50% vs 16%, P = 0.002), Baseline heart rate preceding ventricular arrhythmias did not differ between the two groups.Conclusion: AF is an independent predictor of recurrent ventricular arrhythmias in ICD recipients. The underlying electrophysiologic mechanism seems to be irregular rather than rapid ventricular activation, with a high incidence of short‐long‐short sequences preceding ventricular tachyarrhythmias in AF patients.
Estimation of Atrial Response to Entrainment Pacing Using Electrograms Recorded from Remote Sites
Authors: TRIEDMAN JOHN K. , ALEXANDER MARK E. , BERUL CHARLES L , BEVILACQUA LAURA M. , WALSH EDWARD P. 
Published: August 2003

Determination of Entrainment Response. Introduction: Assessing the entrainment response by measuring pustpacing intervals (PPIs) at the pacing site facilitates localization of reentrant circuits, but may be technically difficult.Methods and Results: There were 269 right atrial sites entrained in 21 circuits in congenital heart patients left atrial (LA) electrograms were recorded. Entrainment response was measured by two methods: (1) PPI‐tachycardia cycle length, and (2) the difference in latencies between the stimulus artifact and the pacing site electrogram, referenced to the LA electrogram. PPI also was measured from the LA as an index of antidromic activation. Among 43 pacing sites with antidromic LA activation, half showed a discrepancy ≥25 msec between methods 1 and 2. At the other 226 sites, agreement between the two methods was high (mean discrepancy ‐3 ± 8 msec, r = 0.975, 0 sites with discrepancy ≥25 msec). Correcting all sites by LA antidromicity reduced the mean discrepancy to +1 ± 6 msec and improved correlation (r = 0.988).Conclusion: LA electrograms can be used to estimate right atrial entrainment response, if antidromic activation of the LA is recognized and taken into account.
Catheter Ablation of Atrial Flutter Guided by Electroanatomic Mapping (CARTO): A Randomized Comparison to the Conventional Approach
Authors: WILLEMS STEPHAN , WEISS CHRISTIAN , VENTURA RODOLFO , RÜPPEL RUDOLF , RISIUS TIM , HOFFMANN MATTHIAS , MEINERTZ THOMAS 
Published: August 2003

Electroanatomic vs Conventional Mapping for Atrial Flutter Ablation. Introduction: Three‐dimensional electroanatomic (CARTO) activation mapping of the cavotricuspid isthmus can be helpful to guide atrial flutter ablation, but to date has not heen investigated in comparison to conventional strategies. The aim of the present study was to assess the efficacy of the CARTO navigation system, especially with respect to the fluoroscopy time required for successful atrial flutter ablation.Methods and Results: Eighty patients with recurrent common‐type atrial flutter were randomly assigned to temperature‐controlled radiofrequency (RF) catheter ablation, either guided by conventional criteria (group 1) or additionally oriented on electroanatomic mapping (group 2). In all patients, similar multipolar catheters were inserted into the coronary sinus and placed at the tricuspid annulus. respectively. In group 2, positioning of the mapping electrode and delivery of RF pulses within the cavotricuspid isthmus was mainly oriented on the CARTO map to achieve the most linear and continuous RF lesions. Abolition of intra‐atrial conduction verified by conventional criteria (group 1) and electroanatomic mapping (group 2) could be verified in all patients. The overall number of RF pulses (group 1: 16.7 ± 6.5; group 2: 13.2 ± 5.3) and mean procedure duration (group 1: 172.5 ± 47.4 min; group 2: 169.3 ± 47.3 min) were not different between the two groups, but mean fluoroscopy time was significantly shorter when the CARTO tecbnology was used (group 1: 29.2 ± 9.4 min; group 2: 7.7 ± 2.8 min; F = 0.0001). Recurrence of atrial flutter was observed in 3 (9%) patients in each group after a mean follow‐up of 8.5 ± 2.months.Conclusion: Atrial flutter can be abolished effectively using the conventional technique as well as oriented on electroanatomic mapping. However, overall X‐ray exposure can he significantly reduced by the CARTO‐guided approach without prolongation of procedure duration.
Effect of Verapamil on Immediate Recurrence of Atrial Fibrillation
Authors: DAOUD EMILE G. , HUMMEL JOHN D. , AUGOSTINI RALPH , WILLIAMS STACY , KALBFLEISCH STEVEN J. 
Published: August 2003

Immediate Recurrence of AF. Introduction: The purpose of this study was to assess the effect of verapamil on immediate recurrences of atrial fibrillation occurring after successful electrical cardioversion.Methods and Results: The effect of verapamil on the recurrence of atrial fibrillation within 5 minutes after successful transthoracic cardioversion was assessed in 19 (5%) of 364 patients undergoing electrical cardioversion. The mean duration of atrial fibrillation was 4.44 ± 3.0 months. In the 19 patients, cardioversion was successful after each of three consecutive cardioversion attempts per patient; however, atrial fibrillation recurred 0.4 ± 0.3 minutes after cardioversion. Verapamil 10 mg was administered intravenously and fourth cardioversion was performed. Cardioversion after verapamil was successful in each patient, and atrial fibrillation did not recur in 9 (47%) of 19 patients (P < 0.001 vs before verapamil). In the remaining 10 patients in whom atrial fibrillation recurred, the duration of sinus rhythm was significantly longer compared with before verapamil (3,6 ± 2.4 min, P < 0.001). The density of atrial ectopy occurring after cardioversion was significantly less after verapamil (21 ± 14 ectopic beats per min) compared with before verapamil (123 ± 52 ectopic beats per min, P < 0.001).Conclusion: Among patients with immediate recurrence of atrial fibrillation after electrical cardioversion, acute calcium channel blockade by verapamil reduces recurrence of atrial fibrillation and extends the duration of sinus rhythm.
Electrophysiologic Endocardial Mapping from a Noncontact Nonexpandable Catheter: A Validation Study of a Geometry‐Based Concept
Authors: JIA PING , PUNSKE BONNIE , TACCARDI BRUNO , RUDY YORAM 
Published: August 2003

Electrophysiologic Noncontact Endocardial Mapping. Introduction: The need for high‐resulution simultaneous mapping of cardiac excitation and arrhythmias on a heat‐hy‐heat basis is widely recognized. Here we validate a noncontact mapping approach that combines a spiral catheter design with mathematical reconstruction to generate potential maps, electrograms, and activation maps (isochrones) on the entire left ventricular endocardial surface during a single beat. The approach is applicable to any heart chamher.Methods and Results: The catheter is 3 mm (9 French) in diameter and carries 96 electrodes. Reconstruction accuracy is evaluated through direct comparison with endocardial data measured with 95 needle electrodes. Results show that endocardial potentials, electrograms, and isochrones are reconstructed with good accuracy during pacing from single or multiple sites (simulating ectopic activity). Pacing sites can be located to within 5 mm of their actual position, and intersite distances of 17 mm can be resolved during dual pacing. The reconstructed potential pattern reflects the intramural depth of pacing. The reconstructions are robust in the presence of geometric errors, and the accuracy is minimally reduced when only 62 catheter electrodes are used (32 are sufficient for pacing site localization).Conclusion: The study demonstrates that simultaneous endocardial mapping can be accomplished during a single beat from a spiral‐shaped noncontact catheter with good accuracy.
Early Down‐Regulation of K+ Channel Genes and Currents in the Postinfarction Heart
Authors: HUANG BOYU , QIN DAYl , EL‐SHERIF NABIL 
Published: August 2003

Down‐Regulation oi K+ Channel Genes and Currents. Introduction: Down‐regulaticn of key K+ channel subunit gene expression and K+ currents is a universal response to cardiac hypertrophy, whatever the cause, including the postmyocdardial infarction (post‐Ml) remodeled heart.Methods and Results: We investigated the hypothesis that down‐regulation of K+ channel genes and currents post‐MI occurs early and before significant remodeled hypertrophy of the noninfarcted myocardium could be detected. We investigated (1) the incidence of induced ventricular tachyar‐rhythmias (VT) in 3‐day post‐MI rat heart; (2) action potential (AP) characteristics of isolated left ventricular (LV) myocytes from sham‐operated and 3‐day post‐MI heart; (3) time course of changes in outward K+ currents Ito‐fast(f) Ikin isolated myocytes from 3‐day and 4‐week post‐MI noninfarcted LV and compared the changes with sham‐operated animals; and (4) changes in the messenger and protein levels of Kv2.1, Kv4.2. and Kv4.3 in the LV and right ventricle of 3‐day post‐MI heart. Sustained VT was induced in 6 of 10 3‐day post‐MI rats and in none of 8 sham rats. The membrane capacitance of myocytes isolated from 3‐day post‐MI noninfarcted LV was not significantly different from control, whereas membrane capacitance 4‐week post‐MI was significantly higher, reflecting the development of hypertrophy. AP duration was increased and the density of Ito‐f and Ik were significantly decreased in 3‐day post‐MI LV myocytes compared with sham. The reduced density of Ito, did not significantly differ in 4‐week post‐MI LV myocytes, whereas the density of Ik was decreased further at 4 weeks post‐MI. The changes in Ito‐f and Ik correlated with decreased messenger and protein levels of Kv4.2/Kv4.3 and Kv2.l, respectively.Conclusion: These results support the hypothesis that down‐regulation of K+ channel gene expression and current in the post‐MI LV occurs early and may be dissociated from the slower time course of post‐MI remodeled hypertrophy. These changes may contribute to early arrhythmogenesis of the post‐MI heart.
Atrial Fibrillation in the Goat Induces Changes in Monophasic Action Potential and mRNA Expression of Ion Channels Involved in Repolarization
Authors: VAN DER VELDEN HUUB M.W. , VAN DER ZEE LUCIE , WIJFFELS MAURITS C.E.F. , VAN LEUVEN CARLO , DORLAND RICK , VOS MARC A. , JONGSMA HABO J. , ALLESSIE MAURITS A. 
Published: August 2003

MAP Changes and Ion Channel Expression in Goat AF. Introduction: Sustained atrial fibrillation (AF) is characterized by a marked shortening of the atrial effective refractory period (AKRP) and a decrease or reversal of its physiolonic adaptation to heart rate. The aim of the present study was to investigate whether the AF‐induced changes in AKKP in the goat are associated with changes in the atrial monophasic action potential (MAP) and whether an abnormal expression of specific ion channels underlies such changes.Methods and Results: Following thoracotomy, MAPs were recorded from the free wall of the right atrium hoth before induction of AF (control) and after cardioversion of sustained AF (>2 months) in chronically instrumented goats. In control goats. MAP duration at 80% repolarization (MAPD80) shortened (P < 0.01) from 132 ± 4 msec during slow pacing (400‐msec interval) to 86 ± 10 msec during fast pacing (180 msec). After cardioversion of sustained AF, the MAPD80, during slow pacing was as short as 67 ± 5 msec (electrical remodeling). Increasing the pacing rate resulted in prolongation (P = 0.02) of the MAPD80 to 91 ± 6 msec. Also. MAPD20 (20% repolarization) shortened (P = 0.05) from 32 ± 4 msec (400 msec) to 14 ± 7 msec (180 msec) in the control goats, whereas it prolonged (P = 0.03) from 20 ± 3 msec (400 msec) to 33 ± 5 msec (180 msec) in sustained AF, mRNA expression of the L‐type Ca2+ channel α1c gene and Kv1.5 potassium channel gene, which underlie Ica, and Ikur respectively, was reduced in sustained.AF compared with sinus rhythm hy 32% (P = 0.01) and 45% (P < 0.01). respectively. No significant changes were found in the mRNA levels of the rapid Na+ channel, the Na+/Ca2+ exchanger, or the Kv4.2/4.3 channels responsible for I10.Conclusion: AF‐induced electrical remodeling in the goat comprises shortening of MAPD and reversal of its physiologic rate adaptation. Changes in the time course of reploarization of the action potential are associated with changes in mRNA expression of the α subunit genes of the L.‐type Ca2+ channel and the Kvl.5 potassium channel.
Connexin40‐Deficient Mice Exhibit Atrioventricular Nodal and Infra‐Hisian Conduction Abnormalities
Authors: VANDERBRINK BRIAN A. , SELLITTO CATERINA , SABA SAMIR , LINK MARK S. , ZHU WEI , HOMOUD MUNTHER K. , ESTES N.A. MARK , PAUL DAVID L. , WANG PAUL J. 
Published: August 2003

AV Nodal and Infra‐Hisian Conduction in Cx40 Mice. Introduction: Previous electrophysiologic investigations have described AV conduction disturbances in connexin4(Cx40)‐deficient mice. Because expression or(Cx40 occurs predominantly in the atria and His‐Purkinje system of the mouse heart, the AV conduction disturbances were thought to be secondary to disruption in His‐Pnrkinje function. However, the lack of a His‐bundle electrogram recording in the mouse has limited further investigation of the importance of Cx40. Using a novel technique to record His‐bundle recordings in Cx40‐deficient mice, we define the physiologic importance of defciencies in Cx40.Methods and Results: Ten Cx40‐/‐ mice and 11 Cx40+/+ controls underwent a blinded, in vivo, closed chest electrophysiology study at 9 to 12 weeks of age. In the Cx40+/+ mice, the PR interval was significantly longer compared with Cx40+/+ mice (44.6 ± 6.4 msec vs 36.0 ± 4.1 msec, P = 0.002). Not only the HV interval (14.0 ± 3.0 msec vs 10.4 ± 1.2 msec, P = 0.003) but also the AH interval (33.2 ± 4.8 msec vs 27.1 ± 3.7 msec, P = 0.006), AV Wenckebach cycle lengths, and AV nodal effective and functional refractory periods were prolonged in Cx40‐/‐ compared with Cx40+/+ mice.Conclusion: Cx40‐deficient mice exhibit significant delay not only in infra‐Hisian conduction, as would be expected from the expression of Cx40 in the His‐Purkinje system but also in the electrophysiologic parameters that reflect AV nodal conduction. Our data suggest a significant role of Cx40 in atrionodal conduction and/or in proximal His‐bundle conduction,
Localization of Arrhythmogenic Triggers of Atrial Fibrillation
Authors: ASHAR MANISHA S. , PENNINGTON JOSEPH , CALLANS DAVID J. , MARCHLINSKI FRANCIS E. 
Published: August 2003

Arrhythmogenic Triggers of Atrial Fibrillation. Introduction: Mapping procedures to identify triggers of atrial fibrillation from pulmonary veins (PVs) are not well established. We sought to determine the value of multipolar recordings from the coronary sinus (CS) and crista terminalis (CT) for identifying the origin of paced and atrial premature depolarizations (APDs) initiating atrial fibrillation from left versus right PVs. Methods and Results: Fifteen patients with paroxysmal atrial fibrillation refractory to medications had decapolar catheters (5‐mm electrode, 2‐nmi interelectrode spacing) placed in the CS and posterior medial to the CT. Bipolar electrograms were recorded at each site. Electroanatomic left atrial endocardial maps were created in sinus rhythm, and each PV was identified and paced. During spontaneous APDs initiating atrial fibrillation and PV pace maps, the atrial activation and the earliest electrogram at CS and CT were compared. PV sites were designated as sites of origin of APDs when (1) intracardiac electrograms in the CS and CT during arrhythmogenic APDs matched those of Pv pace maps, (2) local activation preceded CS and CT recordings by at least 40 msec (all sites), and (3) atrial depolarizations were eliminated by application of radiofrequency energy (24/26 sites). Pacing from each of the 30 right PV sites resulted in proximal to distal CS activation and later recordings at the CS than the CT (earliest CS‐CT activation range: ‐15 to ‐ 58 msec, mean ‐32 ± 12). In contrast, pacing from the left PV sites typically (28/30 sites) activated the CS from the distal to proximal poles and demonstrated simultaneous or earlier (CS‐CT range: ‐14 to +54 msec, mean 13 ± 17) recordings of the CS than the CT (P < 0.0001). For 13 APDs mapped to the right PVs, CS minus CT activation was ‐17 to ‐49 msec (mean ‐ 31 ± 8). For 13 APDs localized to the left PVs, the CS minus CT activation time ranged from ‐8 to +28 msec (mean 14 ± 15). Conclusion: Activation sequence mapping from multipolar catheters placed in the CS and along the posterior medial CT rapidly differentiates right and left PV sites of origin of atrial depolarization.
Importance of the Atrial Channel for Ventricular Arrhythmia Therapy in the Dual Chamber Implantable Cardioverter Defibrillator
Authors: DIJKMAN BARBARA , WELLENS HEIN J.J. 
Published: August 2003

Atrial Channel and VT Therapy in ICD. Introduction: Performance of dual chamber implantable cardioverter defibrillator (ICD) systems bas been judged based on functioning of the ventricular tachycardia:supraventricular tachycardia (VT:SVT) discrimination criteria and DDD pacing. The purpose of this study was to evaluate the use of dual chamber diagnostics to improve the electrical and antiarrhythmic therapy of ventricular arrhythmias. Methods and Results: Information about atrial and ventricular rhythm in relation to ventricular arrhythmia occurrence and therapy was evaluated in 724 spontaneous arrhythmia episodes detected and treated by three types of dual chamber K Ds in 41 patients with structural heart disease. Device programming was based on clinically documented and induced ventricular arrhythmias. In ambulatory patients, sinus tachycardia preceded ventricular arrhythmias more often than in the hospital during exercise testing. The incidence of these VTs could be reduced by increasing the dose of a beta‐blocking agent in only two patients. In five patients in whom sinus tachycardia developed after onset of hemodynamic stable VT, propranolol was more effective than Class III antiarrhythmics combined with another beta‐blocking agent with regard to the incidence of VT and pace termination. In all but three cases, atrial arrhythmias were present for a longer time before the onset of ventricular arrhythmias. During atrial arrhythmias, fast ventricular rates before the onset of ventricular rate were observed more often than RR irregularities and short‐long RR sequences. Dual chamber diagnostics allowed proper interpretation of detection and therapy outcome in patients with different types of ventricular arrhythmia. Conclusion: The advantages of the dual chamber ICD system go further than avoiding the shortcomings of the single chamber system. Information from the atrial chamber allows better device programming and individualization of drug therapy for ventricular arrhythmia.
Effect of Sodium Channel Blockers on ST Segment, QRS Duration, and Corrected QT Interval in Patients with Brugada Syndrome
Authors: SHIMIZU WATARU , ANTZELEVITCH CHARLES , SUYAMA KAZUHIRO , KURITA TAKASHI , TAGUCHI ATSUSHI , AIHARA NAOHIKO , TAKAKI HIROSHI , SUNAGAWA KENJI , KAMAKURA SHIRO 
Published: August 2003

ST Elevation in Brugada Syndrome. Introduction: Brugada syndrome is characterized by an ST segment elevation in leads V1‐V3 and a high incidence of ventricular fibrillation (VF). A mutation in a cardiac Na+ channel gene, SCN5A, has been linked to Brugada syndrome, and sodium channel blockers have been shown to be effective in unmasking the syndrome when concealed. The aim of this study was to examine the effects of Na+ channel blockers on ST segment elevation, QRS, corrected QT (QTc) interval, and ventricular arrhythmias in patients with Brugada syndrome. Methods and Results: We examined the effects of three different Na+ channel blockers (flecainide, disopyramide, and mexiletine) on the amplitude of the ST segment 20 msec after the end of QRS (ST20), QRS duration, QTc interval measured from 12‐lead ECG, and ventricular arrhythmias in 12 Brugada and 10 control patients. Maximum ST20 observed in the V2 or V3 leads under baseline conditions was greater in the Brugada patients than in control patients, whereas QRS duration and maximum QTc interval were no different between the two groups. Flecainide and disopyramide, but not mexiletine, significantly increased maximum ST20 and QRS duration in both groups, although these effects were much more pronounced in the Brugada patients. The increases in ST20 and QRS duration with flecainide were significantly larger than those with disopyramide. An increase of 0.15 mV in ST20 with flecainide separated the two groups without overlap. Ventricular premature complexes developed only with flecainide in Brugada patients (3/12) displaying a marked ST elevation but not widening of QRS. Conclusion: Our findings suggest that Na+ channel blockers amplify existing INa and possibly other ion channel defects, with a potency inversely proportional to the rate of dissociation of the drug from the Na+ channel, thus causing a prominent elevation of the ST segment and, in some cases, prolongation of QRS duration in patients with Brugada syndrome.