bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Defibrillation Outcome by Epicardial Activation Patterns Following Shocks Near the Defibrillation Threshold
Authors: CHATTIPAKORN NIPON , FOTUHI PARWIS C. , IDEKER RAYMOND E. 
Published: April 2007

Activation Patterns and Defibrillation Outcome. Introduction: Ventricular defibrillation is probabilistic and shock strength dependent. We investigated the relationship between defibrillation outcome and postshock activation patterns for shocks of the same strength (‐50% probability of success for defibrillation [ED50] to yield an equal number of successful and failed shocks). Methods and Results: In five pigs, 10 shocks of ED50 strength (right ventricle‐superior vena cava, biphasic, 6/4 msec) were delivered after 10 seconds of ventricular fibrillation (VF). Epicardial activation sequences following shocks were mapped with a 504‐electrode stock and analyzed by animating dV/dt of the electrograms. Intercycle interval (ICI. time between the onset of successive postshock cycles), wavefront conduction time (WCT, time between the earliest and latest activation of a cycle), and overlapping index (WCT of cycle[n]/ICI of cycle[n+1]) were determined for the first five postshock cycles. An overlapping index > 1 indicates overlap between successive cycles. Of 50 defibrillation attempts, 25 were successes. There was no difference between successful and failed episodes for both ICI (68 ± 9 msec vs 62 ± 10 msec) and WCT (97 ± 24 msec vs 100 ± 14 msec) of cycle 1. However, starting at cycle 2, the ICI was longer, and the WCT was shorter for successful than failed episodes (P < 0.01). Overlapping cycles (index > 1) were found during the transition from cycles 2 through 5 in all failed (index >1) and in no successful episodes. Conclusions: (1) Defibrillation outcome cannot be determined during the first postshock cycle. (2) At least three rapid successive cycles with overlap of cycles 2 and 3 are present in all failed and in no successful episodes. (3) The overlapping index is a marker to predict defibrillation outcome.
Pacing Following Shocks Stronger than the Defibrillation Threshold:
Authors: CHATTIPAKORN NIPON , FOTUHI PARWIS C. , IDEKER RAYMOND E. 
Published: April 2007

VF Induction After Defibrillation Shocks. Introduction: A recent study of shocks near defibrillation threshold (DFT) strength demonstrated that at least three rapid cycles always occur after failed shocks but not after successful shocks, suggestion that the number and rapidity of postshock cycles are important in determining defibrillation success. To test this hypothesis, rapid pacing was performed following a shock stronger than the DFT that by itself did not induce rapid cycles and ventricular fibrillation (VF). Methods and Results: Epicardial activation was mapped in six pigs using a 504‐electrode sock. The DFT was determined by an up/down protocol with SI shocks (right ventricle‐superior vena cava, biphasic). Ten shocks that were 100 to 200 V above the DFT (aDFT) were delivered after 10 seconds of VF to confirm they always defibrillated. Then, S2, S3, etc., pacing at 5 to 10 times diastolic threshold was performed from the left ventricular apex after aDFT shocks during VF. First, the postshock interval after aDFT shocks was scanned with an S2 stimulus to find the shortest S1‐S2 coupling interval (CI) that captured. This was repeated for S3, S4, etc., until VF was induced. To induce VF after aDFT shocks, three pacing stimuli (S2, S3, S4) with progressively shorter CIs were always required; S2 or S2, S3 never induced VF. For the S2‐S4 cycles, the intercycle interval was shorter (P < 0.01), and the wavefront conduction time was longer (P < 0.0l) for episodes in which VF was induced (n = 57) than for episodes in which it was not (n = 60). Following the S4 cycle that induced VF, two types of spontaneous activation patterns appeared: focal (88%) and reentrant (12%). Conclusion: VF induction after aDFT shocks always required at least three rapid successive paced‐induced cycles. Thus, the number and rapidity of the first several postshock cycles rather than just the first postshock cycle may be determining factors for defibrillation outcome.
Ablation of Atypical Atrial Flutter Guided by the Use of Concealed Entrainment in Patients Without Prior Cardiac Surgery
Authors: BOGUN FRANK , BENDER BIRGIT , LI YI‐GANG , HOHNLOSER STEFAN H. 
Published: April 2007

Ablation of Atypical Atrial Flutter. Introduction: Mapping techniques have not been systematically evaluated with respect to atypical atrial flutter (AF) not involving the inferior vena cava isthmus. The purpose of this study was to assess prospectively the use of concealed entrainment (CE) in mapping of AF and to assess the clinical benefit of ablation of clinically relevant atypical AF. Methods and Results: In seven consecutive patients without prior cardiac surgery presenting with atypical AF, mapping was performed in the right and, if necessary, left atrium. At sites with CE, radiofrequency energy was delivered. In a posthoc analysis, the endocardial activation time, stimulus‐flutter wave (F) interval, presence of split potentials and diastolic potentials, and postpacing Interval were assessed, and effective sites were compared to ineffective sites. A total of 22 forms of atypical AE either could be induced or were present at the time of the study. Eleven of the 13 targeted atypical AFs (85%) were successfully ablated. The positive predictive value of CE increased from 45% to 75% in the presence of matching electrogram‐F and stimulus‐F intervals or if flutter terminated during entrainment pacing, and to 88% in the presence of split atrial electrograms or diastolic potentials. During short‐term clinical follow‐up, none of the patients had recurrence of the ablated AE. However, the majority of patients required either medication for atrial fibrillation or repeated interventions for new forms of AF. Conclusion: Mapping and ablation of atypical AF is feasible if sites with CE can be identified. However, the clinical benefit of successful ablations in patients with atypical flutter appears to be limited.
Direct Discrimination and Full‐Day Disclosure of Ventricular Parasystole on New Heart Rate Tachograms
Authors: TAKAYANAGI KAN , TANAKA KAZUHTKO , KAMISHIRADO HIROTOSHI , SAKAI YOSHIHIKO , FUJITO TSUNEO , INOUE TERUO , HAYASHI TERUMI , MOROOKA SHIGENORI , IKEDA NORIAKI 
Published: April 2007

Tachographic Discrimination of Parasystole. Introduction: To discriminate ventricular parasystole from fixed coupling interval ventricular premature complexes (VPCs), we developed a new diagnostic method using a dot distribution pattern corresponding to VPCs recorded on a heart rate tachogram using ambulatory ECG monitoring data. We tested our hypothesis that widely scattered VPC dots on instantaneous heart rate tachograms indicate a constant VPC‐VPC interval compatible with parasystole. Methods and Results: Patients with frequent VPCs > 5,000/day) were divided into two groups depending on the tachogram dot distribution patterns: group F (n = 10, aged 61 ± 16 years) showed widely scattered VPC dot distribution, whereas group F (n = 10, 60 ± 17 years) showed fixed VPC dot distribution limited to a narrow zone. Using digitized R‐R interval data, full‐day heart rate tachograms and VPC‐VPC intervals were depicted simultaneously. Group S demonstrated constant basic VPC‐VPC intervals (1,285 to 2,052 msec, mean 1,738 ± 219), with a coefficient of variation (CV) of 0.061 ± 0.018. Their VPC coupling intervals were markedly variable (651 ± 113 msec; CV = 0.193 ± 0.034). Each patient's basic VPC‐VPC intervals showed small diurnal alterations (minimum ‐13%± 3% to maximum +15%± 6%). VPC‐VPC intervals in group F were not constant and showed marked variation. Group F VPC coupling intervals were shorter and constant (480 ± 30 msec, P = 0.0002; with CV = 0.076 ± 0.013, P < 0.0001). Conclusion: Ventricular parasystole with constant VPC‐VPC intervals consistently became evident based on VPC dot patterns recorded on heart rate tachograms.
Altered Transient Outward Current in Human Atrial Myocytes of Patients with Reduced Left Ventricular Function
Authors: SCHREIECK JÜRGEN , WANG YANGGAN , OVERBECK MATTHIAS , SCHÖMIG ALBERT , SCHMITT CLAUS 
Published: April 2007

Ito1 in Human Atrium and Heart Failure. Introduction: Electrophysicologic remodeling is involved in the self‐perpetuation of atrial fibrillation. To define whether differences in atrial electrophysiology already are present in patients with increased susceptibility for atrial fibrillation, we compared patients in sinus rhythm with and without heart failure. Methods and Results: Atrial specimens were obtained from patients with reduced left ventricular ejection fraction (LVEF; n = 10) and normal LVEF (n = 16) who were undergoing aortocoronary bypass surgery and from donor hearts (n = 4). Enzymatically isolated atrial myocytes were investigated by whole cell, patch clamp techniques. Total outward current was significantly larger in myocytes of hearts with low LVEF than normal LVEF (19.4 ± 1.3 vs 15.1 ± 1.2 pA/pF at pulses to +60 mV, respectively). Analysis of inactivation time courses of different outward current components revealed that the observed current difference is due to the transient calcium‐independent outward current Ito1, which is twice as large in the low LVEF group than in the normal LVEF group (9.4 ± 0.9 vs 4.7 ± 0.4 pA/pF at pulses to +60 mV, respectively). Ito1 recovery from inactivation was significantly more rapid in myocytes of hearts with low LVEF, and action potential plateau in these cells was significantly shorter. The results of Ito1 and action potential measurements in atrial myocytes of donor hearts were very similar to the results of patients with preserved heart function. Conclusion: Itto1 in human atrial myocytes of patients with reduced LVEF has an increased density and altered kinetics in sinus rhythm. These differences in outward current may explain the reduced plateau phase of action potentials.
Microwave Ablation Using a Spiral Antenna Design in a Porcine Thigh Muscle Preparation: In Vivo Assessment of Temperature Profile and Lesion Geometry
Authors: VANDERBRINK BRIAN A. , GU ZEJI , RODRIGUEZ VICTOR , LINK MARK S. , HOMOUD MUNTHER K. , III N.A. MARK ESTES , RAPPAPORT CAREY M. , WANG PAUL J. 
Published: April 2007

Microwave Ablation with Spiral Antenna Design. Introduction: Theoretical studies have suggested that microwave energy can increase the depth of heating compared with radiofrequency energy. A spiral microwave antenna design may have advantages over previous designs using smaller designs because the resulting power deposition pattern is considerably larger than the catheter diameter. We tested the efficacy of a spiral antenna using microwave energy in a porcine thigh muscle preparation. Methods and Results: In five anesthetized pigs, the thigh muscle was exposed and bathed in heparinized bovine blood (36° to 37°C). A helical microwave catheter with a fiberoptic thermometer attached to the distal end was positioned perpendicular to the thigh muscle. The antenna‐tissue interface and tissue temperatures at depths of 3.0 and 6.0 mm were measured. A 915‐MHz microwave generator delivered energy at one of three power outputs (50, 100, or 150 W) for 60 seconds. Seventy lesions were created: 50 W (n = 23), 100 W (n = 24), and 150 W (n = 23). The mean depths at 50, 100, and 150 W were 4.3 ± 1.8 mm, 7.2 ± 1.7 mm, and 9.4 ± 0.9 mm, respectively. Lesion depth (R = 0.96, P = 0.05), maximum surface dimension (R = 0.99, P = 0.06), and volume (R = 0.99, P = 0.04) were closely correlated to the power applied. Conclusion: Power is an important determinant of lesion size using a spiral microwave antenna. A novel, spiral microwave antenna design can create lesions of significant depth that may be applicable for the ablative therapy of ventricular tachycardia.
Electrophysiologic Characteristics and Radiofrequency Ablation of Concealed Nodofascicular and Left Anterograde Atriofascicular Pathways
Authors: HLUCHY JAN , SCHICKEL STEFAN , JÖRGER URS , JURKOVICOVA OLGA , SABIN GEORG V. 
Published: April 2007

Nodofascicular and Atriofascicular Pathway Ablation. Introduction: True nodoventricular or nodofascicular pathways and left‐sided anterograde decremental accessory pathways (APs) are considered rare findings. Methods and Results: Two unusual patients with paroxysmal supraventricular tachycardia were referred for radiofrequency (RF) ablation. Both patients had evidence of dual AV nodal conduction. In case 1, programmed atrial and ventricular stimulation induced regular tachycardia with a narrow QRS complex or episodes of right and left bundle branch block not altering the tachycardia cycle length and long concentric ventriculoatrial (VA) conduction. Ventricular extrastimuli elicited during His‐bundle refractoriness resulted in tachycardia termination. During the tachycardia, both the ventricles and the distal right bundle were not part of the reentrant circuit. These findings were consistent with a concealed nodofascicular pathway. RF ablation in the right atrial mid‐septal region with the earliest atrial activation preceded by a possible AP potential resulted in tachycardia termination and elimination of VA conduction. In case 2, antidromic reciprocating tachycardia of a right bundle branch block pattern was considered to involve an anterograde left posteroseptal atriofascicular pathway. For this pathway, decremental conduction properties as typically observed for right atriofascicular pathways could be demonstrated. During atrial stimulation and tachycardia, a discrete AP potential was recorded at the atrial and ventricular insertion sites and along the AP. Mechanical conduction block of the AP was reproducibly induced at the annular level and at the distal insertion site. Successful RF ablation was performed at the mitral annulus. Conclusion: This report describes two unusual cases consistent with concealed nodofascicular and left anterograde atriofascicular pathways, which were ablated successfully without impairing normal AV conduction system.
Typical Atrial Flutter Ablation: Conduction Across the Posterior Region of the Inferior Vena Cava Orifice May Mimic Unidirectional Isthmus Block
Authors: SCAGLIONE MARCO , RICCARDI RICCARDO , CALÒ LEONARDO , DI DONNA PAOLO , LAMBERTI FILIPPO , CAPONI DOMENICO , CODA LUISELLA , GAITA FIORENZO 
Published: April 2007

Atrial Flutter Mapping. Introduction: The aim of this study was to map the low right atrium before and after radiofrequency ablation of the inferior vena cava‐tricuspid annulus (IVC‐TA) isthmus in patients with typical atrial flutter (AFI) to better understand the electrophysiologic meaning of incomplete or unidirectional block following the ablation procedure and its relationship with AFI recurrence. Methods and Results: We performed atrial mapping in 12 patients using a “basket” catheter in the IVC orifice, Halo catheter in the right atrium, and multipolar catheters in the coronary sinus (CS) and His region. In patients in sinus rhythm, atrial activation was analyzed during pacing from the CS and low lateral right atrium (KLRA) before and after ablation. Atrial activation propagated across the isthmus and posterior region of the IVC orifice simultaneously before ablation. Mapping during AFI in four patients showed that the crista terminalis was a site of functional block. After ablation, evaluation of Halo catheter recordings in three patients showed apparent unidirectional counterclockwise block, whereas analysis of basket catheter recordings demonstrated complete bidirectional block. The apparent conduction over the isthmus during pacing from proximal CS was due to conduction along the posterior part of the IVC orifice, which activated the LLRA despite complete isthmus block. Conclusion: Our results demonstrate that limited endocardial mapping may yield a pattern compatible with unidirectional block in the IVC‐TA isthmus, although bidirectional block is present at this anatomic level.
High Uniformity of Left and Right Ventricular Repolarization Dynamics Induced by an Abrupt Decrease in Pacing Cycle Length in a Dog is not Affected by Left Ventricular Ischemia
Authors: LEERSSEN HENDRIK M. , VOS MARC A. , HOUBEN RICHARD , DEN DULK KAREL , WELLENS HEIN J.J. 
Published: April 2007

Ischemia Does Not Alter APD Shortening Dynamics. Introduction: After an abrupt increase in heart rate, action potential duration (APD) will shorten. To assess the effect of ischemia on APD shortening dynamics, we compared right ventricular (RV) and left ventricular (LV) APD shortening induced by an abrupt decrease in pacing cycle length (PCL) during control and LV ischemia. Methods and Results: In eight anesthetized AV block dogs, endocardial LV and RV APD were determined simultaneously after an abrupt PCL decrease from 800 to 350 msec. Measurements were repeated during left anterior descending coronary artery (LAD) occlusion. During control, LV and RV APD shortened 97 ± 27 and 71 ± 14 msec, respectively (P < 0.05). Shortening was pronounced in a short initial phase and gradual in the longer secondary phase. Linear regression analysis revealed very high uniformity of LV and RV APD shortening dynamics (r2= 0.96 ± 0.01). During repeated LAD occlusion, ischemia induced a gradual LV APD shortening from 314 ± 25 msec to a new steady‐state value of 251 ± 23 msec, whereas RV APD remained stable at 289 ± 28 msec. The additional PCL decrease resulted in LV and RV APD shortening of 72 ± 8 and 68 ± 15 msec, respectively, with the same high uniformity of shortening dynamics as seen during control (r2= 0.94 ± 0.03). Conclusion: There is a pronounced difference in APD shortening dynamics induced by an abrupt decrease in PCL compared with ischemia. LV shortening dynamics induced by a decrease in PCL are not affected by LV ischemia, preserving a high interventricular uniformity of repolarization dynamics.
Specific Up‐Regulation of Mitochondrial F0F1‐ATPase Activity after Short Episodes of Atrial Fibrillation in Sheep
Authors: BARBEY ODILE , PIERRE SANDRINE , DURAN MARIE‐JOSÉE , SENNOUNE SOUAD , LÉVY SAMUEL , MAIXENT JEAN‐MICHEL 
Published: April 2007

ATPase Activity and Atrial Fibrillation. Introduction: Ventricular fibrillation induced by either digitalis intoxication or electrical stimulation is reported to alter myocardial energy by impairing the sarcolemmal Na,K‐ATPase or the receptor for digitalis and the mitochondrial ATPase synthase or F0,F1‐ATPase. However, little is known about these membrane functions during atrial fibrillation (AF). Methods and Results: We analyzed the effects of electrically induced AF on biochemical activities of atrial F0F1‐ATPase and Na,K‐ATPase in sheep. A group of six sheep was subjected to direct short electrical stimulation of the right atrium to induce AF. Sham‐operated sheep served as a control group. Microsomal and mitochondrial membranes of atrial muscle were isolated and tested for enzymatic activity. All paced sheep developed multiple episodes of sustained AF, with a mean total duration of 110 minutes over a 2‐hour period. Data showed that short‐term pacing‐induced AF significantly activated membrane F0F1‐ATPase activity (P < 0.05) without changes in cytochrome‐c oxidase activity, Na,K‐ATPase activity, ouabain sensitivity, and α1‐subunit expression. Conclusion: Specific activation of F0F1‐ATPase activity is an early molecular consequence of sustained AF in sheep.
Relationship of Specific Electrogram Characteristics During Sinus Rhythm and Ventricular Pacing Determined by Adaptive Template Matching to the Location of Functional Reentrant Circuits that Cause Ventricular Tachycardia in the Infarcted Canine Heart
Authors: CIACCIO EDWARD J. , SCHEINMAN MELVIN M. , WIT ANDREW L. 
Published: April 2007

Localization of Reentrant Circuits. Introduction: It would be advantageous, for ablation therapy, to localize reentrant circuits causing ventricular tachycardia by quantifying electrograms obtained during sinus rhythm (SR) or ventricular pacing (VP). In this study, adaptive template matching (ATM) was used to localize reentrant circuits by measuring dynamic electrogram shape using SR and VP data. Methods and Results: Four days after coronary occlusion, reentrant ventricular tachycardia was induced in the epicardial border zone of canine hearts by programmed electrical stimulation. Activation maps of circuits were constructed using electrograms recorded from a multichannel array to ascertain block line location. Electrogram recordings obtained during SR/AP then were used for ATM analysis. A template electrogram was matched with electrograms on subsequent cycles by weighting amplitude, vertical shift, duration, and phase lag for optimal overlap. Sites of largest cycle‐to‐cycle variance in the optimal ATM weights were found to be adjacent to block lines bounding the central isthmus during reentry (mean 61.1% during SR; 63.9% during VP). The distance between the mean center of mass of the ten highest ATM variance peaks and the narrowest isthmus width was determined. For all VP data, the center of mass resided in the isthmus region ocurring during reentry. Conclusion: ATM high variance measured from SR/AP data localizes functional block lines forming during reentry. The center of mass of the high variance peaks localizes the narrowest width of the isthmus. Therefore, ATM methodology may guide ablation catheter position without resorting to reentry induction.
Catheter Ablation of Chronic Atrial Fibrillation Targeting the Reinitiating Triggers
Authors: HAÏSSAGUERRE MICHEL , JAÏS PIERRE , SHAH DIPEN C. , ARENTZ THOMAS , KALUSCHE DIETRICH , TAKAHASHI ATSUSHI , GARRIGUE STÉPHANE , HOCINI MÉLÈZE , PENG JING TIAN , CLÉMENTY JACQUES 
Published: April 2007

Trigger Ablation in Chronic AF. Introduction: We assessed the mode of reinitiation of atrial fibrillation (AF) after cardioversion and the efficacy of ablating these foci of reinitiation in patients with chronic AF. Methods and Results: Fifteen patients, 7 with structural heart disease, underwent mapping and catheter ablation of drug‐resistant AF documented to he persistent for 5 ± 4 months. In all patients, cardioversion was followed by documentation of P on T atrial ectopy and early recurrence, which allowed mapping of the reinitiating trigger or the source of ectopy. Radiofrequency (RF) ablation was performed at pulmonary vein (PV) ostia using a target temperature of 50°C and a power limit of 30 to 40 W, with the endpoint being interruption of all local muscle conduction. A total of 32 arrhythmogenic PVs and 2 atrial foci (left septum and left appendage) were identified: 1, 2, and 3 or 4 PVs in 5, 3, and 6 patients. RF applications at the ostial perimeter resulted in progressively increasing delay, followed by abolition of PV potentials in 8, but potentials persisted in 6. A single ablation session was performed in 7 patients and 8 underwent two or three sessions because of recurrence of AF; ablation was directed at the same source due to recovery of local PV potential or at a different PV. No PV stenosis was noted either acutely or at repeated follow‐up angiograms. Nine patients (60%) were in stable sinus rhythm without antiarrhythmic drugs at follow‐up of 11 ± 8 months. Anticoagulants were interrupted in 7 patients. Conclusion: PVs are the dominant triggers reinitiating chronic AF in this patient population. Elimination of PV potentials by ostial RF applications results in stable sinus rhythm in 60%. A larger group and longer follow‐up are needed to investigate further the role of trigger ablation in curative therapy for chronic AF.