bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Biatrial Computerized Mapping During Permanent Atrial Fibrillation in Patients with Organic Heart Disease
Authors: WU TSU‐JUEY , DOSHI RAHUL N. , HUANG HSUN‐LUN A. , BLANCHE CARLOS , KASS ROBERT M. , TRENTO ALFREDO , CHENG WEN , KARAGUEUZIAN HRAYR S. , PETER C. THOMAS , CHEN PENG‐SHENG 
Published: August 2003

Activations in Permanent Atrial Fibrillation.
Introduction: Activation patterns during permanent atrial fibrillation (AF) in patients with organic heart diseases are unclear. Methods and Results: We studied six patients with permanent AF and organic heart diseases undergoing surgery. The duration of AF averaged 4.9 ± 7.6 years. Computerized epicardial mappings of the right atrial (RA) free wall and the left atrial (LA) posterior wall were simultaneously performed with 224 bipolar electrodes at 3‐mm spatial resolution. In the RA, large wavefronts and conduction blocks were frequently observed. The lines of block correlated with the crista terminalis and large pectinate muscles. In contrast, the LA had rapid repetitive activities originated from corners of the electrode plaque, near the four pulmonary veins (PVs). On average, 2.8 ± 1.2 sites of rapid repetitive activities were identified per patient. They activated continuously, intermittently, or alternately during AF. The mean activation cycle length in the RA (196 ± 22 msec) was significantly longer than that in the LA (179 ± 26 msec; P = 0.004). The maximum dominant frequency in the LA was higher than that in the RA (6.41 ± 1.18 Hz vs 5.66 ± 0.55 Hz; P = 0.049). The maximum dominant frequency was consistently located in areas with rapid repetitive activations near the PVs. Conclusion: During human permanent AF associated with organic heart diseases, the activation cycle length was shorter in the LA posterior wall than in the RA free wall. Rapid repetitive activities are consistently observed in the LA posterior wall, at or near the PVs.
Survival of Antiarrhythmic or Implantable Cardioverter Defibrillator Treated Patients with Varying Degrees of Left Ventricular Dysfunction Who Survived Malignant Ventricular Arrhythmias
Authors: DOMANSKI MICHAEL J. , EPSTEIN ANDREW , HALLSTROM AL , SAKSENA SANJEEV , ZIPES DOUGLAS P. 
Published: August 2003

Survival with ICD or Antiarrhythmic Therapy.
Introduction: The relative effectiveness of the implantable cardioverter defibrillator (ICD) and antiarrhythmic drugs (AADs) varies with left ventricular ejection fraction (LVEF). However, once an ICD or AAD treatment strategy is chosen, the degree to which the LVEF influences survival is unknown. This article addresses that question. Methods and Results: Using patient data from the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, the impact of LVEF on prognosis of patients who were treated with either an ICD or AAD was assessed. Survival within each quintile of LVEF was estimated by the method of Kaplan‐Meier for patients treated with either the ICD or AADs. The Cox proportional hazards model was used to investigate the prognostic value of LVEF for estimating survival after adjustment for other baseline covariates among all patients in the subgroups treated by ICD or AAD. In the highest two quintiles of LVEF, survival was comparable in AAD‐treated and ICD‐treated patients. In the AAD‐treated patients, higher LVEF was significantly and independently associated with survival free of all‐cause mortality and arrhythmic death. In the ICD‐treated patients, however, the statistical significance of the association was lost and only a trend toward greater survival was present. Death due to congestive heart failure remained independently and significantly associated with survival in both AAD‐treated and ICD‐treated patients. Conclusion: In patients treated with AADs but not patients treated with ICDs, survival is strongly associated with LVEF. The absence of a statistically significant association in the ICD patients is likely related to the effectiveness of the ICD in treating malignant ventricular arrhythmias, but a chance lack of association cannot be excluded.
Arrhythmogenesis of T Wave Alternans Associated with Surface QRS Complex Alternans and the Role of Ventricular Prematurity: Observations from a Canine Model of LQT3 Syndrome
Authors: CHINUSHI MASAOMI , HOSAKA YUKIO , WASHIZUKA TAKASHI , FURUSHIMA HIROSHI , AIZAWA YOSHIFUSA 
Published: August 2003

Intramural TWA and Its Arrhythmogenesis.
Introduction: T wave alternans (TWA) is characterized by cycle‐to‐cycle changes in the QT interval and/or T wave morphology. It is believed to amplify the underlying dispersion of ventricular repolarization. The aim of this study was to examine the mechanisms and arrhythmogenesis of TWA accompanied by QRS complex and/or blood pressure (BP) waveform alternans, using transmural ventricular electrogram recordings in an anthopleurin‐A model of long QT syndrome. Methods and Results: The cardiac cycle length was gradually shortened by interruption of vagal stimulation, and TWA was induced in six canine hearts. Transmural unipolar electrograms were recorded with plunge needle electrodes from endocardial (Endo), mid‐myocardial (Mid), and epicardial (Epi) sites, along with the surface ECG and BP. The activation‐recovery interval (ARI) was measured to estimate local refractoriness. During TWA, ARI alternans was greater at the Mid than the Epi/Endo sites, and it was associated with the development of marked spatial dispersion of ventricular repolarization. As TWA increased, ventricular activation of the cycles associated with shorter QT intervals displayed delayed conduction at the Mid sites as a result of a critically longer ARI of the preceding cycle and longer QT interval, while normal conduction was preserved at the Epi site. Delayed conduction at the Mid sites manifested as surface ECG QRS and BP waveform alternans, and spontaneous ventricular tachyarrhythmias developed in absence of ventricular prematurity. In other instances, in absence of delayed conduction during TWA, ventricular premature complexes infringed on a prominent spatial dispersion of ventricular repolarization of cycles with long QT intervals and initiated ventricular tachyarrhythmia. Conclusion: TWA accompanied by QRS alternans may signal a greater ventricular electrical instability, since it is associated with intramural delayed conduction, which can initiate ventricular tachyarrhythmia without ventricular premature complexes.
T Wave Alternans Threshold Late After Repair of Tetralogy of Fallot
Authors: CHEUNG MICHAEL M.H. , WEINTRAUB ROBERT G. , COHEN RICHARD J. , KARL TOM R. , WILKINSON JAMES L. , DAVIS ANDREW M. 
Published: August 2003

TWA Threshold After TOF Repair.
Introduction: Sustained microvolt‐level T wave alternans (TWA) is a marker of increased risk for malignant ventricular arrhythmia. There is a significant risk of arrhythmia and sudden death after repair of congenital heart disease. The aim of this study was to determine the prevalence and characteristics of TWA after repair of tetralogy of Fallot (TOF). Methods and Results: TWA was evaluated during bicycle exercise in 49 subjects who had consecutively undergone transatrial‐transpulmonary repair. Median values for age, age at repair, and follow‐up duration were 14.9 years (11.5–20.8), 1.6 years (0.2–4.9), and 11.6 years (9.4–17.2), respectively. All patients were in New York Heart Association functional class I and were asymptomatic. Median QRS duration was 120 msec (80–150). Sustained TWA was detected in 7 (23%) of 31 subjects with adequate tests. In these 7 subjects, median onset heart rate (HR) was 120 (98–155). Median HR threshold as a percentage of predicted maximum HR (220 – age) was 58%(48–77). Sustained TWA prevalence was not significantly different compared with normal subjects (7/31 vs 9/83; P = 0.1). Onset HR in the TOF group was significantly lower [mean (SD) of 122 (20) vs 139 (12), P < 0.05]. In the TOF group with sustained TWA, the TWA occurred in 4 of 7 at < 60% predicted maximum HR versus 1 of 9 normal subjects (P < 0.05); 3 of 7 had onset HR < 120 versus 0 of 9 normal subjects (P < 0.03). There was no significant difference in age, gender, transannular patch use, restrictive right ventricular physiology, QRS duration, QTc, QT/QRS dispersion, or nonsustained ventricular tachycardia in subjects with or those without sustained TWA. Conclusion: The onset HR for sustained TWA is significantly lower after repair of TOF. Further study is required to determine whether this represents an increased risk for arrhythmia in this patient group.
Nonexcitatory Stimulus Delivery Improves Left Ventricular Function in Hearts with Left Bundle Branch Block
Authors: MARROUCHE NASSIR F. , PAVIA STEPHEN V. , ZHUANG SHAOWEI , KIM YUNG‐JIN , TABATA TOMOTSUGU , WALLICK DON , SAAD EDUARDO , ABDUL‐KARIM AHMAD , SCHWEIKERT ROBERT , SALIBA WALID , TCHOU PATRICK , NATALE ANDREA 
Published: August 2003

Nonexcitatory Stimulation.
Introduction: Preliminary data in a heart failure animal model and isolated muscle preparation have suggested that nonexcitatory stimulation (NES) improves left ventricular (LV) function. Methods and Results: We compared biventricular (BV) pacing with NES in an animal model with left bundle branch block (LBBB). The left bundle branch (LBB) was ablated in eight normal heart pigs and led to > 50% increase in QRS duration (mean 100 ± 15 msec). End‐diastolic LV pressure, end‐systolic LV pressure, LV pressure (LV dP/dtmax), aortic pulse pressure, and LV ejection fraction were measured before pre‐LBB ablation and compared with post‐LBB ablation (AAI pacing), BV pacing, NES delivery, and BV + NES. Moreover, to evaluate LV diastolic function, we measured the early (E wave) and late flows (A wave) through the mitral valve using spectral Doppler. Compared with post‐LBB ablation, NES led to a significant increase in LV dP/dtmax (1,047 ± 224 mmHg/sec vs 897 ± 116 mmHg/sec; P < 0.05), LV ejection fraction (64% ± 18% vs 49% ± 17%; P < 0.05), and aortic pulse pressure (18 ± 3.6 mmHg vs 16 ± 2.8 mmHg; P < 0.05). Moreover, improvement in LV hemodynamic parameters was significantly higher during NES delivery when compared with BV pacing. No significant changes in E wave, A wave, and E/A were recorded during NES, NES + BV, and BV pacing. Conclusion: Our preliminary data demonstrate that NES is superior to BV pacing in improving LV function in an animal model with LBBB. Moreover, we demonstrated that NES does not affect transmitral valve flow and subsequently LV diastolic function.
Identification and Characterization of Atrioventricular Parasympathetic Innervation in Humans
Authors: QUAN KARA J. , LEE JAI H. , VAN HARE GEORGE F. , BIBLO LEE A. , MACKALL JUDITH A. , CARLSON MARK D. 
Published: August 2003

AV Parasympathetic Innervation.
Introduction: We hypothesized that in humans there is an epicardial fat pad from which parasympathetic ganglia supply the AV node. We also hypothesized that the parasympathetic nerves innervating the AV node also innervate the right atrium, and the greatest density of innervation is near the AV nodal fat pad. Methods and Results: An epicardial fat pad near the junction of the left atrium and right inferior pulmonary vein was identified during cardiac surgery in seven patients. A ring electrode was used to stimulate this fat pad intraoperatively during sinus rhythm to produce transient complete heart block. Subsequently, temporary epicardial wire electrodes were sutured in pairs on this epicardial fat pad, the high right atrium, and the right ventricle by direct visualization during coronary artery bypass surgery in seven patients. Experiments were performed in the electrophysiology laboratory 1 to 5 days after surgery. Programmed atrial stimulation was performed via an endocardial electrode catheter advanced to the right atrium. The catheter tip electrode was moved in 1‐cm concentric zones around the epicardial wires by fluoroscopic guidance. Atrial refractoriness at each catheter site was determined in the presence and absence of parasympathetic nerve stimulation (via the epicardial wires). In all seven patients, an AV nodal fat pad was identified. Fat pad stimulation during and after surgery caused complete heart block but no change in sinus rate. Fat pad stimulation decreased the right atrial effective refractory period at 1 cm (280 ± 42 msec to 242 ± 39 msec) and 2 cm (235 ± 21 msec to 201 ± 11 msec) from the fat pad (P = 0.04, compared with baseline). No significant change in atrial refractoriness occurred at distances > 2 cm. The response to stimulation decreased as the distance from the fat pad increased. Conclusion: For the first time in humans, an epicardial fat pad was identified from which parasympathetic nerve fibers selectively innervate the AV node but not the sinoatrial node. Nerves in this fat pad also innervate the surrounding right atrium.
Characteristics of Right Atrial Activation During Coronary Sinus Pacing
Authors: BETTS TIM R. , HO SIEW YEN , SANCHEZ‐QUINTANA DAMIAN , ROBERTS PAUL R. , ANDERSON ROBERT H. , MORGAN JOHN M. 
Published: August 2003

Activation Patterns and Coronary Sinus Pacing.
Introduction: Anatomic and electrical connections between the left atrium and right atrium (RA) have been described. The relationship between coronary sinus (CS) pacing site and RA activation has not been examined. Methods and Results: Fifteen anesthetized swine underwent high‐density noncontact mapping of the RA during pacing from up to five different sites within the CS. Isopotential mapping identified the site of earliest RA depolarization and the pattern of subsequent activation. Hearts were excised and endocardial dissection performed. Earliest RA activation occurred at the CS os with proximal CS pacing sites and at Bachmann's bundle at distal pacing sites. The mean depth at which a shift in earliest RA activation site occurred was 46 ± 13 mm (range 21 to 63 mm). RA activation times following earliest activation at the CS and Bachmann's bundle were 40 ± 4 msec and 51 ± 6 msec (P < 0.002). Conduction delay or block was recorded at the lateral cavotricuspid isthmus, terminal crest, and tendon of Todaro. Latest RA activation always occurred in the high anterolateral atrium after ascending the anterolateral wall. The lateral RA was activated by the wavefront that traversed the posterior wall rather than by the wavefront crossing the cavotricuspid isthmus, even with earliest RA activation at the CS os. Conclusion: The site of earliest RA activation during CS pacing is dependent upon the pacing depth within the CS. In the porcine heart, areas of conduction delay influence RA activation patterns and timings. These findings may have implications for patients undergoing assessment of radiofrequency ablation of atrial flutter.
Endocardial Mapping of Electrophysiologically Abnormal Substrates and Cardiac Arrhythmias Using a Noncontact Nonexpandable Catheter
Authors: JIA PING , PUNSKE BONNIE , TACCARDI BRUNO , RUDY YORAM 
Published: August 2003

Noncontact Mapping of Arrhythmogenic Substrates.
Introduction: In previous studies, we established methodology for reconstructing endocardial potential maps, electrograms, and isochrones from a noncontact intracavitary catheter during a single beat. Recently, we evaluated this approach using a 9‐French (3‐mm) spiral catheter in a normal heart preparation. Here we extend the approach to hearts with structural disease and examine its ability to detect and characterize abnormal electrophysiologic (EP) substrates and to map ventricular arrhythmias on a beat‐by‐beat basis. Methods and Results: Reconstruction of endocardial potentials from cavity potentials measured with 82 electrodes mounted on a 9‐French spiral catheter was performed in an isolated canine left ventricle (LV). Endocardial potentials were recorded with 91 intramural needles, providing a gold standard for evaluating the noncontact reconstruction. Studies were performed in a normal LV (control) and the same LV 3 hours after left anterior descending coronary artery occlusion and ethanol injection to create an infarct. Abnormal EP characteristics over the infarct were faithfully reconstructed, including (1) low potentials and electrogram derivatives; (2) fractionated electrograms; (3) small deflections on electrograms reflecting local activation; and (4) slow discontinuous conduction transverse to fibers. During arrhythmia, beat‐to‐beat dynamic shifts of initiation site and activation pattern were captured by the reconstruction. Conclusion: Noncontact, nonexpendable catheter mapping can locate and characterize abnormal EP substrates and can capture the endocardial sequence of an arrhythmia during a single beat.
Effect of Action Potential Duration and Conduction Velocity Restitution and Their Spatial Dispersion on Alternans and the Stability of Arrhythmias
Authors: BANVILLE ISABELLE , GRAY RICHARD A. 
Published: August 2003

Restitution and Spatial Heterogeneities vs Arrhythmias.
Introduction: The slope of the action potential duration (APD) restitution curve has been used to explain wavebreaks during arrhythmia initiation and maintenance. This hypothesis remains incomplete to fully describe the experimental data. Other factors contributing to wavebreaks must be studied to further understand arrhythmia dynamics. Methods and Results: Control APDs were measured from isolated rabbit hearts using a monophasic action potential probe. APD and conduction velocity (CV) restitution were quantified over the heart surface for two drugs, diacetyl monoxime (DAM) and cytochalasin D (CytoD), using a dual camera video imaging system. For all pacing intervals: (1) control APDs were shorter than for CytoD but longer than for DAM; and (2) CV was greater for CytoD compared with DAM. APD dispersion increased as pacing interval decreased for both drugs. For DAM, increased dispersion was due to a difference in APD restitution between the right and left ventricle. For CytoD, increased dispersion was due to discordant alternans, with no significant spatial variation in restitution. Fibrillation was sustained only in the control hearts; with DAM, stable reentry was sustained with shorter APD and cycle length compared with CytoD for which only nonsustained unstable reentry occurred. Conclusion: Alternans and arrhythmia dynamics are affected by the spatial dispersion of APD restitution as well as CV restitution, not simply the slope of APD restitution. Therefore, a direct link of the APD restitution slope to alternans and arrhythmia dynamics in rabbit heart does not exist. Designing antiarrhythmic drugs to alter only the restitution slope may not be appropriate.
Noninvasive Assessment of Cardiac Resynchronization Therapy for Congestive Heart Failure Using Myocardial Strain and Left Ventricular Peak Power as Parameters of Myocardial Synchrony and Function
Authors: POPOVIĆ ZORAN B. , GRIMM RICHARD A. , PERLIC GEORGE , CHINCHOY EDWARD , GERACI MARIA , SUN JING PING , DONAL ERWAN , XU XIAO‐FANG , GREENBERG NEIL L. , WILKOFF BRUCE L. , THOMAS JAMES D. 
Published: August 2003

Resynchronization Therapy for Heart Failure.
Introduction: Although invasive studies have shown that cardiac resynchronization therapy by biventricular pacing improves left ventricular (LV) function in selected heart failure patients, it is impractical to apply such techniques in the clinical setting. The aim of this study was to assess the acute effects of cardiac resynchronization therapy by noninvasive techniques. Methods and Results: Twenty‐two patients enrolled in the InSync trial (age 64 ± 9 years, 18 men and 4 women; all with ejection fraction <35% and QRS >130 msec) were studied 1 to 12 months after pacemaker implantation during pacing, and while ventricular pacing was inhibited. Regional myocardial strains of the interventricular septum, LV free wall, and right ventricular free wall were derived from color Doppler tissue echocardiography. Peak power index was calculated as a product of simultaneously recorded noninvasive blood pressure and pulse‐wave (PW) Doppler velocity of the LV outflow tract. The Z ratio (sum of LV ejection and filling times divided by RR interval) and tei index were calculated from PW Doppler data. During pacing, overall regional strain improved (P = 0.01), while the LV strain coefficient of variation decreased from 2.7 ± 2.4 to 1.3 ± 0.7 (P = 0.009). Additionally, peak power index improved from 84 ± 24 to 94 ± 27 cm· mmHg/sec (P = 0.004). The Z ratio increased from 0.71 ± 0.08 to 0.78 ± 0.07 (P = 0.0005), while the tei index decreased from 0.86 ± 0.33 to 0.59 ± 0.16 (P = 0.0002). Conclusion: Using novel noninvasive indices, we demonstrated that cardiac resynchronization therapy improves LV performance.
Accessory Pathway Localization by QRS Polarity in Children with Wolff‐Parkinson‐White Syndrome
Authors: BOERSMA LUCAS , GARCÍA‐MORAN EMILIO , MONT LLUÍS , BRUGADA JOSEP 
Published: August 2003

AP Localization by QRS Polarity in Children.
Introductions: Location of the accessory pathway (AP) in Wolff‐Parkinson‐White (WPW) syndrome can be determined accurately by the QRS polarity on resting ECG. These ECG characteristics may be different in children, and no algorithm has yet been tested. Methods and Results: A total of 153 resting ECGs of symptomatic children with WPW syndrome were retrospectively analyzed. The anatomic AP location had been established fluoroscopically at eight possible sites during radiofrequency catheter ablation. Two independent observers predicted AP location on blinded ECGs with a QRS polarity algorithm for adults using leads II, III, aVL, V1, and V2. Subsequently, the QRS polarity for all individual ECG leads was evaluated and a new algorithm for children was devised. With the adult algorithm, the observers correctly predicted only 55% to 58% of AP locations. The septal and right‐sided pathways often were inseparable, and mid‐septal and parahisian pathways were missed. In the new children's algorithm, left lateral, left posteroseptal, and posteroseptal pathways shared a positive or intermediate QRS polarity on V1, with the left lateral pathway separated by a positive QRS polarity on lead III. Negative QRS polarity on lead V1 and positive QRS polarity on lead V3 were shared by right posteroseptal, mid‐septal, parahisian, and anteroseptal pathways, with the latter two having a positive QRS polarity on lead aVF. Right lateral pathways had negative QRS polarity on lead V1 and negative or intermediate QRS polarity on lead V3. Overall accuracy for these five regions was 90%. Conclusion: AP characterization by QRS polarity in children with WPW syndrome is more diverse than in adults and requires other ECG leads to establish five AP regions.