bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intra‐Atrial Reentrant Tachycardia After Palliation of Congenital Heart Disease:
Authors: TRIEDMAN JOHN K. , JENKINS KATHY J. , COLAN STEVEN D. , SAUL J. PHILI , WALSH EDWARD P. 
Published: April 2007

Catheter Mapping of IART. introduction: The anatomic substrate of intra‐atrial reentrant tachycardia (IART) following congenital heart surgery is poorly understood, but is presumed to be different than common atrial flutter. Methods and Results: To study the mechanisms of IART, we used a new technique for high‐density endocardial mapping using recordings from a multipolar basket recording catheter (25 bipolar pairs). For each recording, biplane fluorographic reference points were digitized to obtain the spatial locations of electrode pairs, and activation times were calculated using temporal reference points from the surface ECG. Using custom software, data were combined to create three‐dimensional atrial activation sequence maps, which were displayed as animated sequences. Using this technique, recordings were made in induced and/or spontaneous IART in 8 patients following congenital heart surgery (5 Fontan, 2 tetralogy of Fallot repair, 1 ventricular septal defect repair), and in 3 patients with normal intracardiac anatomy (I with type I atrial flutter). Ten discrete IART activation sequences were recorded; 2 patients had 2 sequences each. IART maps were constructed using a median of 108 electrode positions (range 27 to 197) from a median of 6 recordings/sequence (range 3 to 11). Sinus or paced atrial rhythms were also recorded, and maps were created in a similar fashion. Visual analysis of activation sequences of sinus and paced rhythm were anatomically concordant with known mechanisms of atrial activation. IART sequences revealed diverse mechanisms; only 1 IART circuit was similar to that associated with common atrial flutter. Activation wavefront emergence from presumed zones of slow conduction, lines of conduction block, and apparent bystander activation were observed. Conclusions: High‐density atrial activation sequence maps demonstrate that IART following congenital heart surgery utilizes diverse circuits and is distinct from common atrial flutter. The technique used to create these three‐dimensional activation sequences may improve understanding of these complex atrial arrhythmias and assist in the development of ablative therapies.
High‐Resolution Fluorescent Imaging Does Not Reveal a Distinct Atrioventricular Nodal Anterior Input Channel (Fast Pathway) in the Rabbit Heart During Sinus Rhythm
Authors: EFIMOV IGOR R. , FAHY GERARD J. , CHENG YUANNA , VAN WAGONER DAVID R. , TCHOU PATRICK J. , MAZGALEV TODOR N. 
Published: April 2007

Fluorescent Imaging of AVN. Introduction: We sought to determine the precise pathways of engagement of the AV node during sinus rhythm. Methods and Results: Langendorff‐perfused rabbit hearts were stained with 20 μM of the voltage‐sensitive dye di‐4‐ANEPPS. Preparations containing the right atrium, sinoatrial (SA) and AV nodes, and interatrial septum were subsequently dissected and mapped in vitro using a 16 × 16 photodiode array with an adjustable resolution of 150 to 750 μm per diode. Motion artifacts were eliminated by using 15 mM 2,3‐butanedione monoxime (BDM). Activation time‐points were defined as (‐dF/dt)max, where F = fluorescence. Isochronal maps of activation were plotted using the triangulation method. In all preparations, spontaneous activation began at the SA node, rapidly spread along the crista terminalis (CrT), entered the AV nodal region via the posterior “slow” pathway, and retrogradely spread to the septal region with a smaller conduction velocity compared to that along the CrT. Collision of anterograde and retrograde wavefronts was frequently observed in the mid‐septum. Notably, there was no evidence for the presence of a distinct anterior entrance into the AV node. Conclusion: Fast pathway conduction during sinus rhythm results from a broad posterior wavefront that envelops the AV node with subsequent retrograde atrial septal activation.
Noncontact Endocardial Mapping: Reconstruction of Electrograms and Isochrones From Intracavitary Probe Potentials
Authors: LIU ZHIWEI W. , JIA PING , ERSHLER PHILIP R. , TACCARDI BRUNO , LUX ROBERT L. , KHOURY DIRAR S. , RUDY YORAM 
Published: April 2007

Noncontact Endocardial Mapping.Introduction: Mapping endocardial activation and repolarization processes is critical to the study of arrhythmias and selection of therapeutic procedures. Previously, we developed methodology for reconstructing endocardial potentials from potentials measured with a noncontact, intracavitary probe. This study further develops and evaluates the ability of the approach to provide detailed information on the spatiotemporal characteristics of the activation process. Specifically, we reconstructed endocardial electrograms and isochrones throughout the activation process over the entire endocardium during a single beat.Methods and Results: Cavity potentials were measured with a 65‐electrode probe placed inside an isolated canine left ventricle. Endocardial potentials were measured simultaneously using 52 electrodes. Potentials were acquired during subendocardial pacing from different locations. Computed electrograms at various sites closely resemble the measured electrograms (correlation coefficient > 0.9 at 60% of the electrodes). Computed isochrones locate subendocardial pacing sites with 10‐mm accuracy. Two pacing sites, 17 mm apart, were resolved. Critical regions, such as areas of isochrone crowding, were accurately reconstructed.Conclusions: Results indicate the applicability of the approach to mapping the cardiac excitation process on a beat‐by‐beat basis without occluding the ventricle. The ability of locating electrical events (e.g., single or multiple initiation sites) is demonstrated. Importantly, the method is shown to be capable of reconstructing electrograms over the entire endocardium and determining nonuniformities of activation spread (e.g., areas of slow conduction). These capabilities are important to clinical application in the electrophysiology laboratory and experimental studies of arrhythmias in the intact animal.
Ablation of Ventricular Tachycardia Associated with Tetralogy of Fallot: Demonstration of Bidirectional Block
Authors: HORTON RODNEY P. , CANBY ROBERT C. , KESSLER DAVID J. , JOGLAR JOSE A. , HUME ANDREW , JESSEN MICHAEL E. , SCOTT WILLIAM P. , PAGE RICHARD L. 
Published: April 2007

Ablation of VT in Tetralogy of Fallot. Introduction: Ventricular tachycardia is commonly seen in patients following surgical repair for tetralogy of Fallot. The technique of ablation for this arrhythmia is not well defined. Methods and Results: In two patients with ventricular tachycardia following surgical repair of tetralogy of Fallot, the traditional indicators for a site for ventricular tachycardia ablation did not yield cure. Based on careful mapping, the circuit was found to involve the isthmus between the outflow tract patch and the tricuspid annulus; linear radiofrequency lesions across this isthmus resulted in cure of ventricular tachycardia. Not only was the tachycardia no longer inducible, but bidirectional block at the line of ablation confirmed interruption of the reentrant circuit. Conclusion: A linear radiofrequency lesion was effective in eliminating ventricular tachycardia in both patients. The demonstration of bidirectional block confirms a cure independent of inducibility of ventricular tachycardia.
Electrophysiologic Characteristics and Radiofrequency Catheter Ablation in Atrioventricular Node Reentrant Tachycardia with Second‐Degree Atrioventricular Block
Authors: LEE SHIH‐HUANG , CHEN SHIH‐ANN , TAI CHING‐TAI , CHIANG CHERN‐EN , WEN ZU‐CHI , UENG KWO‐CHANG , CHIOU CHUEN‐WANG , CHEN YI‐JBN , YU WEN‐CHUNG , HUANG JIN‐LONG , CHENG JUN‐JACK , CHANG MAU‐SONG 
Published: April 2007

Second‐Degree AV Block During AVNRT. Introduction: Detailed electrophysiologic study of AV nodal reentrant tachycardia (AVNRT) with 2:1 AV block has been limited. Methods and Results: Six hundred nine consecutive patients with AVNRT underwent electrophysiologic study and radiofrequency catheter ablation of the slow pathway. Twenty‐six patients with 2:1 AV block during AVNRT were designated as group I, und those without this particular finding were designated as group II. The major findings of the present study were: (1) group I patients had better anterograde and retrograde AV nodal function, shorter tachycardia cycle length (during tachycardia with 1:1 conduction) (307 ± 30 vs 360 ± 58 msec, P < 0.001), and higher incidence of transient bundle branch block during tachycardia (18/26 vs 43/609, P < 0.001) than group II patients: (2) 21 (80.8%) group I patients had alternans of AA intervals during AVNRT with 2:1 AV block. Longer AH intervals (264 ± 26 vs 253 ± 27 msec, P = 0.031) were associated with the blocked beats. However, similar HA intervals (51 ± 12 vs 50 ± 12 msec, P = 0.363) and similar HV intervals (53 ± 11 vs 52 ± 12, P = 0.834) were found in the blocked and conducted beats; (3) ventricular extrastimulation before or during the His‐bundle refractory period bundle could convert 2:1 AV block to 1:1 AV conduction. Conclusions: Fast reentrant circuit, rather than underlying impaired conduction of the distal AV node or infranodal area, might account for second‐degree AV block during AVNRT. Slow pathway ablation is safe and effective in patients who have AVNRT with 2:1 AV block.
Paroxysmal Atrioventricular Block Induced During Head‐Up Tilt Testing in an Apparently Healthy Man
Authors: SUMIYOSHI MASATAKA , NAKATA YASURO , MINEDA YORIAKI 
Published: April 2007

Paroxysmal AV Block During HUT Testing. Introduction: Prolonged asystole during head‐up tilt testing has been reported, but the occurrence of paroxysmal AV block appears to he rare. Methods and Results: A 25‐year‐old man with no history of syncope underwent head‐up tilt testing. After 11 minutes of 80° tilting, he developed syncope with paroxysmal AV block and asystole lasting 10.5 seconds. However, this response was not reproduced during a subsequent tilt test 4 weeks later. Treadmill exercise testing and Holter monitoring showed no abnormalities. Power spectral analysis of heart rate variability revealed a marked increase in sympathetic activity several minutes before the induction of paroxysmal AV block. Conclusion: We report a case of paroxysmal AV block that occurred during head‐up tilt testing but did not recur on a subsequent test in an apparently healthy young man.
Electrophysiology of the Atrio‐AV Nodal Inputs and Exits in the Normal Dog Heart
Authors: HIRAO KENZO , SCHERLAG BENJAMIN J. , POTY HERVE , OTOMO KENICHIRO , TONDO CLAUDIO , ANTZ MATTHIAS , PATTERSON EUGENE , JACKMAN WARREN M. , LAZZARA RALPH 
Published: April 2007

Ablation of Atrionodal Connections. Introduction: We studied the effects of selective and combined ablation of the fast (FP) and slow pathway (SP) on AV and VA conduction in the normal dog heart using a novel epicardial ablation technique. Methods and Results: For FP ablation, radiofrequency current (RFC) was applied to a catheter tip that was held epicardially against the base of the right atrial wall. SP ablation was performed epicardially at the crux of the heart. Twenty‐three dogs were assigned to two ablation protocols: FP/SP ablation group (n = 17) and SP/FP ablation group (n = 6). In 12 of 17 dogs, FP ablation prolonged the PR interval (97 ± 10 to 149 ± 22 msec. P < 0.005) with no significant change in anterograde Wenckebach cycle length (WBCL), Subsequent SP ablation performed in 8 dogs further prolonged tbe PR interval and the anterograde WBCL (117 ± 22 to 193 ± 27, P < O.(M)5). Complete AV block was seen in I of 8 dogs, whereas complete or high‐grade VA block was seen in 6 of 8 dogs. In the SP/FP ablation group, SP ablation significantly increased WBCL with no PR changes. Combined SP/FP ablation in A dogs prolonged the PR interval significantly, but no instance of complete AV block was seen. VA block was found in 50% of these cases. Histologic studies revealed that RFC ablation affected the anterior and posterior atrium adjacent to the undamaged AV node and His bundle. Conclusion: Using an epicardial approach, combined ablation of tbe FP and SP AV nodal inputs can be achieved with an unexpectedly low incidence of complete A V block, although retrograde VA conduction was significantly compromised.
Mode of Onset of Malignant Ventricular Arrhythmias in Idiopathic Ventricular Fibrillation
Authors: VISKIN SAMI , LESH MICHAEL D. , ELDAR MICHAEL , FISH ROMAN , SETBON ISRAEL , LANIADO SHLOMO , BELHASSEN BERNARD 
Published: April 2007

Mode of Onset of Idiopathic VF. Introduction: The mode of onset of malignant ventricular arrhythmias (ventricular tachycardia [VT] or ventricular fibrillation [VF] has been well described in patients with organic heart disease and in patients with the long QT syndromes. Less is known about the mode of onset of VF in patients with out‐of‐hospital VF who have no evidence of organic heart disease or identifiable etiology. Methods and Results: We reviewed the ECGs of all our patients with Idiopathic VF. Documentation of the onset of spontaneous arrhythmias was available for 22 VK episodes in 9 patients (6 men and 3 women; age 41 ± 16 years). In all instances, spontaneous VF followed a rapid polymorphic VT, which was initiated by premature ventricular complexes (PVCs) with very short coupling intervals. The PVC initiating VF had a coupling interval of 302 ± 52 msec and a prematurity index of 0.4 ± 0.07. These PVCs occurred within 40 msec of the peak of the preceding T wave. Pause‐dependent arrhythmias were never observed. Concltision: Cardiac arrest among patients with idiopathic VF has a very distinctive mode of onset. Documentation of a polymorphic VT that is not pause dependent is of diagnostic value.
Use of Only a Regular Diagnostic His‐Bundle Catheter for Both Fast and Reproducible “Para‐Hisian Pacing” and Stable Right Ventricular Pacing
Authors: HEIDBÜCHEL HEIN , ECTOR HUGO , ADAMS JEF , VAN DE WERF FRANS 
Published: April 2007

Pacing from the Diagnostic His‐Bundle Catheter. Introduction: Para‐Hisian pacing, i.e., pacing the anteroseptal right ventricle (RV) with or without direct capture of the His bundle (HB), allows the differentiation of VA conduction over the AV node from conduction over an accessory pathway. Classically, it is performed by maneuvering a separate pacing catheter around the HB catheter, which may be difficult and time‐consuming. Methods and Results: This study prospectively evaluated the use of a single standard octapolar HB catheter with 2‐mm interelectrode spacing for simultaneous (para‐Hisian) pacing from the distal bipole and recording from the three proximal bipoles in 148 consecutive patients. Para‐Hisian pacing was successful in 146 of 148 patients, performed within a median of only 10 seconds, and easily repeated several times during the course of an electrophysiologic study. Retrograde HB activation could he recorded in 132 of 146 patients; a clearly different surface ECG configuration confirmed the presence or absence of HB capture in all other patients. Interestingly, stable RV pacing could he performed from the HB catheter for the rest of the electrophysiologic study in 138 of 142 patients in whom this was tried. RV pacing from this site also led to better interpretation of retrograde conduction, due to clear visualization of retrograde HB activation. Conclusion: Pacing from the distal dipole of a regular diagnostic HB catheter provides a fast and reliable way to perform para‐Hisian pacing. Therefore, it may be advocated as a routine diagnostic protocol during electrophysiologic procedures. Moreover, pacing from this site obviates the need for a separate RV pacing catheter in most patients.
Ablation of Ventricular Tachycardia Due to a Postinfarct Ventricular Septal Defect:
Authors: ELLISON KRISTIN E. , STEVENSON WTLLIAM G. , COUPER GREGORY S. , FRIEDMAN PETER L. 
Published: April 2007

Outer Loop Tachycardia. Introduction: Ventricular tachycardia (VT) alter postinfarct ventricular septal defect (VSD) repair has not been well characterized. Methods and Results: A 55‐year‐old man developed refractory VT after inferior wall infarction and VSD repair. Entrainment demonstrated a broad reentry circuit path (outer loop) between the tricuspid annulus and VSD patch. A series of radiofrequency (RF) lesions transected this path, abolishing VI’ and producing conduction block between the inferior and superior aspects of the basal right ventricular septum. Conclusion: Some VTs have broad reentry loops requiring ablation by a series of RF lesions across the path to create a line of block. This approach is analogous to that for atrial flutter.
Carotid Sinus Hypersensitivity in Patients Undergoing Coronary Arteriography:
Authors: KALLIKAZAROS IOANNIS , STRATOS COSTAS , TSIOUFIS COSTAS , STEFANADIS CHRISTODOULOS , SIDERIS ASIMAKIS , SIDERIS SKEVOS , TOUTOUZAS PAVLOS 
Published: April 2007

Carotid Sinus Hypersensitivity and Atherosclerosis. Introduction: The purpose of the present investigation was to study the precise relationship between carotid sinus hypersensitivity (CSH) and both the severity of carotid atherosclerosis and the extent of coronary artery disease in patients who were referred for evaluation for suspected ischemic heart disease. Methods and Results: Duplex echocardiography and coronary angiography were used to assess carotid and coronary artery atherosclerosis in 130 consecutive patients. Carotid sinus stimulation was performed before coronary arteriography with simultaneous recordings of the ECG and aortic pressure. Coronary artery disease was present in 103 patients (79%). Thirty patients (23.08%) had one‐vessel disease (1‐VD), 31 (23.85%) had 2‐VD, 29 (22.31%) had 3‐VD, and 13 patients (10%) had left main coronary artery disease. Carotid artery atherosclerosis was present in 100 patients (76.92%) and carotid disease (diameter stenosis ≥ 50%) was present in 24 patients (18.46%). CSH was found in 33 patients (25%). The incidence of CSH was 9% in patients with carotid stenosis 1%‐15%, 17% in patients with stenosis 16%‐49%, 85% in patients with stenosis 50%‐79%, and 100% in patients with stenosis ≥ 80%. The incidence of CSH was 11%, 17%, 23%, 34%, and 62% in patients with no VD, 1‐VD, 2‐VD, 3‐VD, and left main coronary artery disease, respectively. Stepwise multiple logistic regression analysis revealed that carotid disease and left main coronary artery disease were the most significant determinants of CSH (P < 0.001 and P = 0.013, respectively). Conclusion: The incidence of CSH increased in proportion to the severity of carotid and coronary atherosclerosis. These data provide evidence that CSH is closely related to severe carotid atherosclerosis or left main coronary artery disease in patients being evaluated for suspected ischemic heart disease.
Comparison of the Effects of Regional Ischemia and Hyperkalemia on the Membrane Action Potentials of the In Situ Pig Heart
Authors: WATANABE ICHIRO , KANDA AKIHIRO , ENGLE CONNIE L. , GETTES LEONARD S. 
Published: April 2007

APD During Ischemia. Introduction: This study was designed to determine the role of increased extracellular potassium [K+]e on action potential duration (APD) in the in situ porcine heart during acute regional no‐flow ischemia. Methods and Results: In open chest, anesthetized swine, an arterial shunt from the carotid artery to the mid‐left anterior descending coronary artery was created through which a solution of KCl was infused to raise [K+]e, Myocardial [K+]e, was determined by potassium‐sensitive electrodes, and transmembrane action potential was recorded by floating glass microelectrode. During the first 2 minutes of ischemia, APD at 90% repolarization (APD90) lengthened by 31.2 ± 1.1 msec (P < 0.05). The comparable increase in [K+]e alone shortened APD90, During the next 6 minutes of ischemia. [K+]e, rose to 11.3 ± 0.3 mM and APD90, showed a decrease. However, the comparable increase in |K+]e, by infusion of KCl caused further shortening of APD90, at similar levels of [K+]e. Conclusions: Acutely ischemic myocardium showed a brief increase in APD90, during the first 2 minutes of ischemia, followed by a fall in APD90, after 2 minutes of ischemia, but the shortening is less than anticipated by the rise in [K+]e. Thus, we hypothesize that other component(s) of ischemia may inhibit action potential repolarization.
Importance of Electrode Conductive Surface Area and Edge Effects on Ventricular Defibrillation Efficacy
Authors: TOMASSONI GERY , Ph.D. RAJESH PENDEKANTI , DIXON‐TULLOCH ELLEN , MINER BILL , FAIN ERIC S. , HOFEMANN DREW A. , WOLF PATRICK D. 
Published: April 2007

Surface Area, Edge Effects, and Ventricular Defibrillation. Introduction: The role of edge effects and electrode surface area of the right ventricular (RV) trausveuous lead (TVL) on defibrillation efficacy is unknown. Methods and Results: Defibrillation threshold (DFT) testing was conducted randomly in 12 dogs using ring electrode leads in an RV/SVC (superior vena cava) or RV/SVC/patch system. The leads (RV‐4, RV‐8t, RV‐8, RV‐15) had electrode surface areas of 20%, 20%, 40%, and 70%, respectively. A computer model predicted the magnitude of electrode surface current (RV‐8t > RV‐4 > RV‐8 > RV‐15) and the potential distribution (PD) at four sites: electrode surface (site a) and at 2 mm (b), 4 mm (c), and 8 mm (d) away from the surface. Despite different near‐field PDs (sites a, b, c), PDs were nearly identical at site d. Resistance decreased as the surface area increased. DFT energy for the RV‐15 lead was lower than the RV‐4 and RV‐8t. There was no difference between energy requirements for the RV‐15 and RV‐8 leads. No difference was found in DFT current for each lead. Comparison of the RV‐8t and RV‐4 leads showed no difference in DFT energy despite a lower resistance and a greater number of edges. Conclusions: Increasing the RV TVL surface area lowered the resistance. However, surface area coverages ≥ 40% did not lower DFT energy. No significant change in DFT current occurred despite different predicted near‐Held current densities. PDs were nearly identical 8 mm from the electrode surface. Thus, the far‐field current density appears to play a more important role in determining defibrillation success.