bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Endocardial Activation Times at Effective and Ineffective Ablation Sites Within the Pulmonary Veins
Authors: TSE HUNG‐FAT , LAU CHU‐PAK , KOU WILLIAM , PFLOSI FRANK , ORAL HAKAN , KIM MICHAEL , MICHAUD GREGORY F. , KNIGHT BRADLEY P. , MOSCUCCI MAURO , STRICKBERGER S. ADAM , MORADY FRED
Published: April 2007

Pulmonary Vein Arrhythmias. Introduction: Recent studies demonstrated that atrial arrhythmias may be generated within pulmonary veins. The purpose of this study was to compare the endocardial activation times at effective and ineffective ablation sites during radiofrequency catheter ablation of arrhythmias initiated or generated within pulmonary veins.

Methods and Results: Twenty‐one of 28 patients without structural heart disease underwent successful ablation of 23 arrhythmogenic foci within a pulmonary vein. Electrograms were recorded at 75 pulmonary venous sites and categorized into three groups: 23 successful ablation sites; 28 unsuccessful target sites within an arrhythmogenic pulmonary vein; and 24 sites within nonarrhythmogenic pulmonary veins. The endocardial activation time of premature depolarizations arising at successful target sites was significantly earlier than at other sites. During premature depolarizations, an endocardial activation time of ‐75 msec or earlier had a sensitivity of 83% and a specificity of 79% for identification of a successful ablation site. Endocardial activation times earlier than ‐100 msec were recorded only at successful ablation sites, and endocardial activation times later than ‐30 msec were recorded only at sites within nonarrhythmogenic pulmonary veins. The presence of a split potential during sinus rhythm or premature depolarizations was not a specific indicator of a successful ablation site.

Conclusion: The endocardial activation times of premature depolarizations that arise within pulmonary veins and initiate atrial tachycardia/fibrillation are useful in identifying successful ablation sites.
Pacing in Right Ventricular Dysplasia after Disconnection Surgery
Authors: TANG CHUEN , KLEIN GEORGE J. , GUIRAUDON GERARD M. , YEUNG‐LAI‐WAH JOHN A. , QI ANZHEN , KERR CHARLES R.
Published: April 2007

Pacing in Right Ventricular Dysplasia. This report describes a 33‐year‐old patient with arrhythmogenic right ventricular (RV) dysplasia who had a dual chamber pacemaker implanted at age 23 years for drug‐induced bradycardia. Pacing was continued after right ventricular free‐wall disconnection (RVFVVD) at age 24 years. Her pacemaker was not replaced after battery depletion 7 years later. She presented the following year in severe right‐sided heart failure. Her old pacemaker generator was replaced. This was followed by rapid resolution of her clinical failure and return to a full, active, physical lifestyle. This observation suggests the potential benefit of dual chamber pacing in patients with RV dysplasia after RVFWD.
Radiofrequency Catheter Ablation of Atrial Fibrillation Initiated by Pulmonary Vein Ectopic Beats
Authors: Miller John M. , CHEN SHIH‐ANN , TAI CHING‐TAT , TSAI CHIN‐FENG , HSIEH MING‐HSIUNG , DING YU‐AN , CHANG MAU‐SONG
Published: April 2007

Ablation of AF Initiated by PV Ectopic Beats. Ectopic beats from the pulmonary veins (PVs) have been demonstrated to initiate atrial fibrillation (AF). This article describes the conceptual approach to mapping, interpretation of different electrograms, and ablation of AF initiated by PV ectopic beats.
Prevalence and significance of Exit Block During Arrhythmias Arising in Pulmonary Veins
Authors: TSE HUNG‐FAT , LAU CHU‐PAK , KOU WILLIAM , PELOSI FRANK , ORAL HAKAN , KIM MICHAEL , F GREGORY , P BRADLEY , MOSCUCCI MAURO , STRICKBERGER S. ADAM , MORADY FRED
Published: April 2007

Exit Block. Introduction: Recent studies described the occurrence of conduction block within pulmonary veins. The purpose of this study was to evaluate the prevalence of exit block during arrhythmias that arise in pulmonary veins.

Methods and Results: Twenty‐five patients with atrial tachycardia/fibrillation underwent successful ablation of 28 arrhythmogenic foci within a pulmonary vein. The prevalence of exit block in the pulmonary veins was determined in 28 arrhythmogenic pulmonary veins and 40 nonarrhythmogenic pulmonary veins. During isolated premature depolarizations, exit block in a pulmonary vein was observed at 50% of arrhythmogenic pulmonary vein sites and was never observed within pulmonary veins that did not generate a tachycardia (P < 0.01). During tachycardia, exit block from a pulmonary vein was observed in 61% of the arrhythmogenic pulmonary veins. The mean cycle length of the pulmonary vein tachycardias associated with exit block was significantly shorter than the cycle length of tachycardia that were not associated with exit block (163 ± 32 vs 251 ± 45 msec, P < 0.001), Exit block in two pulmonary veins during the same episode of tachycardia was observed in 3 of the 28 arrhythmogenic pulmonary veins (11%) in three different patients. Simultaneous recordings in the two pulmonary veins demonstrated bursts of tachycardia in both veins that were not synchronized. Radiofrequency catheter ablation of the arrhythmogenic site in one of the pulmonary veins eliminated spontaneous recurrences of tachycardia from the other pulmonary vein.

Conclusion: Exit block from pulmonary veins is a common observation during tachycardias generated within pulmonary veins and indicates that an arrhythmogenic pulmonary vein has been identified. The occurrence of exit block in more than one pulmonary vein most likely is attributable to simultaneous tachycardias, one or both of which may be tachycardia induced and perpetuated by the other.
Junctional Rhythm During Slow Pathway Radiofrequency Ablation in Patients with Atrioventricular Nodal Reentrant tachycardia: Beat‐to‐Beat Analysis and Its Prognostic Value in Relation to Electrophysiologic and Anatomic Parameters
Authors: PORET PHILIPPE , LECLERCQ CHRISTOPHE , GRAS DANIEL , MASOUR HASSAN , FAUCHIER LAURENT , DAUBERT CLAUDE , MABO PHILIPPE
Published: April 2007

Junctional Rhythm and Slow Pathway Ablation. Introduction: Junctional rhythm usually is considered a sensitive hut nonspecific marker of successful ablation of the slow pathway in AV nodal reentrant tachycardia. Nevertheless, this junctional rhythm has been little studied, and its relations to recognized predictors of successful radiofrequency (RF) application were never established in any study.

Methods and Results: Thirty‐nine patients underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia. Ninety RF applications were delivered, and each ablation site was determined using three different fluoroscopic projections. Six anatomic zones were defined from low posterior septum to the site of distal His‐bundle recording (P1, P2, Ml, M2, Al, and A2). Characteristics of junctional rhythm during RF applications were analyzed. Atrial electrogram characteristics at the ablation sites also were studied. All patients had successful slow pathway ablation, without any complication. The ablation sites were located as follows: 41 at PI. 26 at P2, 20 at Ml, and 3 in M2. Forty RF applications were successful: 14 of 41 attempts at P1, 7 of 26 at P2, 16 of 20 at M1, and 3 of 3 at M2. Mid‐septal ablation site (Ml and M2) was associated with higher occurrence of junctional rhythm (P < 0.0001), earlier first junctional heat (P = 0.008), and earlier occurrence of the longest junctional burst (P = 0.03) compared with posterior ablation site (P1 and P2). The combination of a mid‐septal ablation site and a first junctional heat occurring ≤3 seconds after onset of RF application identified successful RF application with 100% accuracy. Using multivariate analysis, the ablation site, duration of atrial electrogram (including slow pathway potential when present), and occurrence of junctional rhythm were independent predictors of success.

Conclusion: Successful slow pathway ablation depends on many factors. Junctional rhythm characteristics are related to the site of RF delivery and can be helpful in assessing successful slow pathway ablation.
Late Fields of the Magnetocardiographic QRS Complex as Indicators of Propensity to Sustained Ventricular Tachycardia after Myocardial Infarction
Authors: KORHONEN PETRI , MOINTONEN JUHA , MÄKINÄRVI MARKKU , KATILA TOIVO , NIEMINEN MARKKU S. , TOIVONEN LAURI
Published: April 2007

MCG Late Fields and Propensity to VT. Introduction: Magnetocardiographic (MCG) mapping is a new method to record cardiac signals. This study examined the association of MCG late fields with the propensity to sustained ventricular tachycardia (VT) after myocardial infarction (MI).

Methods and Results: One hundred patients with remote Ml were studied, 38 with and 62 without history of VT. High‐resolution MCG and signal‐averaged ECG (SAECG) as a comparative method were recorded. Time‐domain parameters describing the abnormal low‐amplitude end QRS activity, MCG late fields, and SAECG late potentials were analyzed. Late field parameters differed significantly between the patient groups: filtered QRS duration was 137 ± 26 msec in the VT group and no ± 18 msec in the control group (P < 0.001), and root mean square amplitude of the last 40 msec was 260 ± 170 and 510 ± 360 IT (P < 0.001), respectively. The optimal MCG parameter combination yielded a sensitivity of 92% and a specificity of 61% in classification to the VT group, whereas those for SAECG were 63% and 66%. In a subgroup of 63 patients with marked left ventricular dysfunction and comparable stage of coronary heart disease, only MCG (sensitivity 73%, specificity 67%) but not SAECG could assign a patient to the VT group.

Conclusion: Late fields of the MCG QRS complex indicate propensity to life‐threatening arrhythmias in post‐MI patients. This discriminative ability persists in the presence of severe left ventricular dysfunction where KCG late potentials lose their informative value. MCG late field analysis is a potential new method for noninvasive risk assessment in post‐MI patients.
Inhibition of Na,K‐ATPase by External Electrical Cardioversion in a Sheep Model of Atrial Fibrillation
Authors: MAIXENT JEAN‐MICHEL , BARBEY ODILE , PIERRE SANDRINE , DURAN MARIE‐JOSÉE , SENNOUNE SOUAD , BOURDEAUX MADELEINE , RICARD PHILIPPE , LÉVY SAMUEL
Published: April 2007

Na,K‐ATPase and Cardioversion. Introduction: Electrical external cardioversion commonly used to treat atrial fibrillation (AF) is associated with myocardial membrane damage and disturbances in ionic homeostasis (hemodynamically unstable). The present study was designed to investigate whether alterations in ionic homeostasis observed were due in part to changes in the myocardial activity of Na,K‐ATPase.

Methods and Results: AF was induced by pacing in ten anesthetized sheep divided into two groups. Group I (n = 4) received a single external countershock of 360 J after three episodes of AF lasting 10 minutes. Group II (n = 6) served as controls. Activity, responsiveness to ouabain, and membrane expression of catalytic α and β subunits of Na,K‐ATPase in sarcolemmal myocardial membrane fractions were investigated. Membrane fluidity and fatty acid composition, and plasma levels of atrial natriuretic factor (ANF) also were measured. One shock after episodes of AF significantly decreased ventricular Na,K‐ATPase activity up to 50% IP < 0.001) without modification of atrial activity at the membrane level. Sites with low affinity to ouabain showed a fivefold lower affinity for ouabain in the cardioversion group than in the control group (IC50= 7.9 μmol/L vs 40 μmol/L ouabain, P < 0.05). Plasma levels of ANF were significantly increased in the cardioversion group compared with the control group. These changes were independent of membrane modulation in terms of expression of Na,K‐ATPase, membrane fluidity, and fatty acid composition.

Conclusion: This study suggests that left ventricular perturbation of ionic homeostasis subsequent to transthoracic cardioversion could result from inactivation of Na,K‐ATPase activity.
Block of IKs Does Not Induce Early Afterdepolarization Activity but Promotes β‐Adrenergic Agonist‐Induced Delayed Afterdepolarization Activity
Authors: BURASHNTKOV ALEXANDER , ANTZELEVITCH CHARLES
Published: April 2007

Block of IK Does Not Induce EADs.
Introduction: An early afterdepolarization (EAD)‐induced triggered heat is thought to precipitate torsade de pointes (TdP) in the long QT syndrome (LQTS). Previous studies demonstrated the development of EAD activity and dispersion of repolarization under LQT2 (reduced IKr) and LQT3 (augmented late INa). but not LQTl (reduced IKs), conditions. The present study examines these electrophysiologic characteristics during IKs block.

Methods and Results: Canine epicardial (Epi), M, and endocardial (Endo) tissues and Purkinje fibers isolated from the canine left ventricle were studied using standard microelectrode recording techniques. The IKs blocker chromanol 293B (293B, 30 μM), produced a homogeneous rate‐independent prolongation of action potential duration (APD) in Epi, M, and Endo, but little to no APD prolongation in Purkinje. Chromanol 293B I to 30 μM failed to induce EADs or delayed afterdepolarizations (DADs) in any of the four tissue types. Isoproterenol (ISO, 0.1 to 1.0 μM) in the presence of 293B 30 μM significantly prolonged the APD of the M cell (basic cycle length ≥ sec), abbreviated that of Purkinje, and caused little change in that of Epi and Endo. The combination of 293B 30 μM and ISO 0.2 μM did not induce EADs in any of the four tissue types, but produced DAD activity in 4 of 8 Epi, 7 of 10 M cells, and 3 of 8 Endo.

Conclusion: Our results indicate that IKs block alone or in combination with β‐adrenergic stimulation does not induce EADs in any of the four canine ventricular tissue types, but that the combination of the two induces DADs as well as accentuated dispersion of repolarization.
Exit Block of Focal Repetitive Activity in the Superior Vena Cava Masquerading as a High Right Atrial Tachycardia
Authors: INO TAKESHI , MIYAMOTO SHINJIRO , OHNO TADAAKI , TADERA TAKESHI
Published: April 2007

AT Originating from the SVC. An unusual case of atrial tachycardia (AT) originating from the superior vena cava (SVC) is reported. A 34‐year‐old man without structural heart disease underwent catheter ablation for drug‐resistant AT. During the tachycardia, low‐amplitude spiky electrograms with a cycle length of 120 to 175 msec were recorded in the SVC and exhibited 2:1 exit block to the atria, masquerading as the atrial activation observed with high right AT. These spiky electrograms also were observed during sinus rhythm, but they appeared immediately after the local atrial electrograms. The spikes were traced to a point 3 cm above the junction of the right atrium. Radiofrequency ablation at the site of the earliest appearance of the spike in the SVC successfully eliminated the tachycardia. During the following 15 months, no clinically significant atrial arrhythmias, including atrial fibrillation, occurred. This report indicates that careful mapping, including inside the SVC, will be a requisite in patients with high right atrial tachyarrhythmias.
Helical Representation of Atrial Reentry: A Teaching Aid for Electrophysiology
Authors: COSÍO FRANCISCO G.
Published: April 2007

Loop Diagrams of Reentry. Cardiac clinical electrophysiology is difficult to teach because it requires mental integration of complex information on cardiac activation, which includes tridimensional spatial orientation of the cardiac structures involved and variables such as refractory period, conduction velocity, and cycle length. Commonly used representations of cardiac arrhythmias include snapshot sequences or ladder diagrams. The former lack time dimension, and the latter lack spatial dimension. We propose a schematic tridimensional representation of reentry as a helicoidal shape that is the result of adding a time dimension to a circular representation. This presentation, which also can be called a “loop diagram,” allows better integration of spatial phenomena with recorded electrogram sequences and can help the teaching of basic clinical electrophysiology.
Catheter Ablation for Hemodynamically Unstable Monomorphic Ventricular Tachycardia
Authors: ELLISON KRISTIN E. , STEVENSON WILLIAM G. , SWEENEY MICHAEL O. , LEEROY DAVID C. , DELACRETAZ ETIENNE , FRIEDMAN PETER L.
Published: April 2007

Ablation of Unstable Ventricular Tachycardia. Introduction: Hemodynamic collapse precludes extensive catheter mapping to identify focal target regions in many patients with ventricular tachycardia (VT) associated with heart disease. This study tested the feasibility of catheter ablation of poorly tolerated VTs by targeting a region identified during sinus rhythm.

Methods and Results: Ablation was attempted in five patients, ages 44 to 59 years, with left ventricular ejection fractions of 0.15 to 0.20 and poorly tolerated VT causing multiple implantable defibrillator therapies (6 to 30 episodes/month). VT was due to prior infarction in three patients and nonischemic cardiomyopathy in two. Target regions were sought that met the following criteria: (1) evidence of slow conduction from fractionated sinus rhythm electrograms and stimulus‐QRS delays during pace mapping, and (2) evidence that the region contains the reentrant circuit exit from pace mapping. In 4 of 5 patients, a target region was identified and radiofrequency lesions applied. Ablation abolished all recurrences of VT in 3 of 4 patients during follow‐up of 14 to 22 months. There were no complications.

Conclusion: Ablation of poorly tolerated VT is feasible in some patients by mapping during sinus rhythm and performing ablation over a region of identifiable scar that contains abnormal conduction and a presumptive VT exit.
Ionic Basis for Action Potential Prolongation by Phenylephrine in Canine Epicardial Myocytes
Authors: ROBINSON RICHARD B. , LIU QIN‐YUE , ROSEN MICHAEL R.
Published: April 2007

Phenylephrine Action on Repolarization. Introduction: In canine ventricle, α‐adrenergic agonists prolong action potential duration (APD) without any effect on the action potential notch, suggesting that, in this species, the effect on repolarization might he independent of inhibition of Ito. The present study investigated the action of the α‐adrenergic agonist phenylephrine on the action potential and the repolarizing currents Ito and IK in isolated canine epicardial myocytes.

Methods and Results: Isolated cells from canine epicardial tissue, and Purkinje fibers, were studied with the whole cell, voltage clamp method. Phenylephrine 0.1 μM increased APD by 13%± 4% at 90% repolarization without affecting the notch or amplitude. Under voltage clamp, concentrations of phenylephrine as high as 10 μM had no effect on Itp in canine epicardial myocytes. However, Ito of isolated canine Purkinje myocytes was reduced to 69%± 7% of control by 1 μM phenylephrine. Further studies in canine epicardial myocytes revealed an action of phenylephrine to inhibit Ik, and in particular IKs Using a voltage protocol that included a two‐step repolarization to separate IKs and IKr tail components, the largely 1Ke, component was not significantly affected by 1 μM phenylephrine, whereas the largely IKs component was reduced to 81%± 5% of control value.

Conclusion: α‐Adrenergic prolongation of repolarization in canine epicardium does not result from inhibition of Ito. Rather, it appears that reduction of IKs contributes to the action of phenylephrine. The unresponsiveness of epicardial Ito is not a general characteristic of the canine heart, because Purkinje myocyte Ito was inhibited, suggesting regional differences in the molecular basis of lto, and/or a‐adrenergic signaling in the canine heart.
How Constant Anatomically is the Tendon of Todaro as a Marker for the Triangle of Koch?
Authors: YEN HO SIEW , ANDERSON ROBERT H.
Published: April 2007

Tendon of Todaro. Introduction: Although well recognized by anatomists as a border of the triangle of Koch demarcating the location of the A V node, the tendon of Todaro is not visible in the operating room or in the catheterization laboratory. Instead, clinicians use as surrogate a projected line between the eustachian valve and the central fibrous body. The constancy of the tendon of Todaro within this border remains to be determined.

Materials and Results: We reexamined serial histologic sections from 25 adults and 50 infants and gross dissections in four normal hearts. The tendon of Todaro was identified in all cases and traced to the central fibrous body in all but one case. It tended to be thicker in the hearts of infants cases (0.2 to 0.8 mm vs 0.1 to 0.6 mm). The tendon and the binge‐line of the septal leaflet of the tricuspid valve were consistent as landmarks for location of the compact AV node in all the cases studied by histology. Gross dissections traced the tendon to the free edge of the eustachian valve.

Conclusion: The tendon of Todaro is present in hearts obtained from both adults and infants. It or its surrogate, is a reliable border for the triangle of Koch and serves as a landmark to location of the atrial components of the AV conduction axis.
An Innovative Application of Anatomic Electromagnetic Voltage Mapping in a Patient with Ebstein's Anomaly Undergoing Permanent Pacemaker Implantation
Authors: KLOOSTERMAN E. MARTIN , YAMAMURA KENNETH , ALBA JULIA , MITRANI RAUL D. , MYERBURG ROBERT J. , INTERIAN ALBERTO
Published: April 2007

Anatomic Electromagnetic Voltage Mapping. A novel application of the Biosense CARTO System anatomic electromagnetic voltage mapping is presented, utilized as a guide for permanent pacemaker placement. The technique is illustrated in the successful implantation of an atrial lead in a patient with Ebstein's anomaly characterized by a severely dilated right atrium and extremely low‐amplitude voltage signals, requiring a DDD pacemaker. Electromagnetic voltage mapping can be used in selected patients with structural heart disease to determine the optimal site for permanent pacemaker lead placement.
Gender‐Related Differences in Modulation of Heart Rate in Patients with Congestive Heart Failure
Authors: ARONSON DORON , BURGER ANDREW J.
Published: April 2007

Gender and HRV in Heart Failure

Introduction. The prognosis of women with congestive heart failure (CHF) is better than that for men, but the mechanisms underlying the female survival advantage are not well understood. CHF is characterized by profound abnormalities in cardiac autonomic control that contribute to progressive circulatory failure and influence survival.

Methods and Results. Time‐ and frequency‐domain heart rate variability (HRV) indexes were obtained from 24‐hour Holter recordings and compared to assess the role of gender in 131 men and 68 women with CHF (mean age 60 ± 13.6 years, range 21 to 87; New York Heart Association Functional Class III [66%] and IV [34%]). Gender‐related differences in HRV were observed only in the subset of patients with nonischemic heart failure (55 men and 39 women). Among the time‐domain indexes, the SD of the RR intervals (76 ± 5.3 msec vs 55.3 ± 3.2 msec, P < 0.0001) and indexes denoting parasympathetic modulation, the percentage of RR intervals with >50 msec variation (4.0%± 1.0% vs 6.5%± 1.3%, P = 0.02), and the square root of mean squared differences of successive RR intervals (19.1 ± 3.3 vs 28.4 ± 3.8, P = 0.004) were higher in women. Among the frequency‐domain indexes, the total power (7.5 ± 0.13 In‐msec2 vs 8.3 ± 0.14 In‐msec2, P = 0.0002), the ultralow‐frequency power (7.2 ± 0.11 In‐msec2 vs 8.0 ± 0.14 In‐msec2, P < 0.0001), the low‐frequency power (3.8 ± 0.25 In‐msec2 vs 4.8 ± 0.28 In‐msec2, P = 0.006), and the high‐frequency power (3.8 ± 0.24 In‐msec2, vs 4.6 ± 0.26 In‐msec2, P = 0.003) were greater in women than in men.

Conclusion. Women with nonischemic CHF have an attenuated sympathetic activation and parasympathetic withdrawal compared with men. Gender‐based differences in autonomic responses in the setting of CHF may be related to the female survival advantage. (J Cardiovasc Electrophysiol, Vol. 11, pp. 1071‐1077, October 2000)
Circadian Variation of Vasovagal Syncope
Authors: MINEDA YORIAKI , SUMIYOSHI MASATAKA , TOKANO TAKASHI , YASUDA MASAYUKI , NAKAZATO KAORU , NAKAZATO YUJI , NAKATA YASURO , YAMAGUCHI HIROSHI
Published: April 2007

Circadian Variation of Vasovagal Syncope. Introduction. Circadian patterns have been demonstrated for several cardiovascular catastrophes. Chronobiologic factors play a role in the emergence of vasovagal syncope (VVS); however, diurnal variation of syncopal episodes in VVS has not been reported previously.

Methods and Results. We assessed daily distribution of the time of syncopal episodes in VVS. Time of syncope could be determined in 80 episodes in 54 patients (32 men and 22 women; mean age 37 years, range 12 to 67). Patients who were prescribed beta blockers or vasodilators, and who had syncopes related to alcohol intake, were excluded from the study. Head‐up tilt testing was performed in 53 patients. The distribution of the episodes of VVS in 3‐hour intervals differed significantly from uniform occurrence (P < 0.0001). with a peak frequency between 6 A.M. and noon (67.5% of total episodes). In patients who had experienced the initial syncope in the morning, most (78%) of the next syncopal episodes also occurred in the morning. There was no significant correlation between the time of last syncopes and tilt testing results.

Conclusion. We demonstrated a prominent circadian variation in the frequency of VVS, with a peak in the morning. Recognition of the daily distribution of VVS is useful for patient education and therapeutic strategy. (J Cardiovasc Eleciroptiysiol. Vol. 11. pp. 1078‐1080, October 2000)
Long‐Term Effects of Biatrial Synchronous Pacing to Prevent Drug‐Refractory Atrial Tachyarrhythmia: A Nine‐Year Experience
Authors: D'ALLONNES GILLES REVAULT , PAVIN DOMINIQUE , LECLERCQ CHRISTOPHE , ECKE JEAN EMMANUEL , JAUVERT GAEL , MABO PHILIPPE , DAUBERT JEAN‐CLAUDE
Published: April 2007

Biatrial Pacing for Atrial Tachyarrhythmia Prevention. Introduction. Results of previous studies suggest that atrial resynchronization by multisite atrial pacing may coutribute to prevention of recurrences in patients with drug‐refractory atrial tachyarrbythmias and significant intra‐atrial conduction delay.

Methods and Results. To verify this hypothesis, a prospective noncontrolled study of 86 patients (mean age 66 ± 10 years) was conducted in a single center between January 1989 and February 1998. Inclusion criteria were P wave duration ≥120 msec with interatrial conduction time ≥100 msec, and history of multiple recurrences of atrial tacbyarrbythmias (mean 7 ± 4.8 episodes) evolving in a persistent mode for at least 6 montbs despite optimized drug treatment (mean 2.7 ± 1.8 drugs/patient). Patients were chronically implanted with a pacing system that ensured permanent biatrial pacing using two atrial leads, one placed in the high right atrium and the other one into the mid or the distal part of the coronary sinus. P wave duration decreased from a mean value of 187 ± 29 msec before implant to 106 ± 14 msec (P < 0.0001) under biatrial pacing. After a 33‐month mean follow‐up (range 6 to 109), 55 patients (64%) remained in sinus rhythm, including 28 patients (32.6%) without any documented recurrence and 27 patients with one or more recurrences in a paroxysmal or in a persistent form. In these 55 patients, drug treatment was significantly reduced in relation to the preimplantation period (1.4 ± 0.6 vs 1.7 ± 0.5 drugs/patient; P = 0.011). The other 31 patients went into chronic atrial arrhythmia after a mean period of 26 momths. The only predictive factor of positive response was a spontaneous P wave duration ≤160 msec at baseline.

Conclusion. The results are consistent with a preventive effect of permanent biatrial pacing on recurrent and drug‐refractory atrial arrhythmias associated with intra‐atrial conduction delay. (J Cardiovasc Electrophy, Vol. 11, pp. 1081‐1091, October 2000)
Dual Chamber Arrhythmia Detection in the Implantable Cardioverter Defibrillator
Authors: DIJKMAN BARBARA , WELLENS HEIN J.J.
Published: April 2007

Dual Chamber Arrhythmia Detection hy ICD. Introduction. Dual chamber implantable cardioverter detibrillator (ICD) technology extended ICD therapy to more than termination of hemodynamicaly unstable ventricular tachyarrhythmias. It created the basis for dual chamber arrhythmoa management. In which dependable detection is important for treatment and prevention of both ventricular and atrial arrhythmias.

Methods and Results. Dual chamber detection algorithms were investigated in two Medironic dual chamber ICDs; the 7250 Jewel AF (33 patients) and the 7217 Gem DR (31 patients). Both ICDS use the same PR Logic algorithm to interpret tachycardia as ventricular tachycardia (VT), supraventricular tachycardia (SVT), or dual (VT+SVT), The accuracy of dual chamber detection was studied in 310 of 1,367 spontaneously occurring tachcardias in which rate criterion only was not sufficient for arrhythmia diagnosis. In 78 epidoses there was a double tachycardia, in 223 episodes. SVT was detected in the VT or veutricular fibrillation zone, and in 9 episodes arrhythmia was detected outside the boundaries of the PR Logic functioning. In 100% of double techycardias the VT was correctly diagonsed and reveived priority treatment. SVT was seen in 59 (19%) episodes diagonsed as VT. The causes of inappropriate detection were (1) algorithm failure (inability to fulfill the PR<RP condition in atrial tacharrhythmias with 1:1 AV conduction, and far‐filed R wave sensing intermittently present during sinus tachycardia); (2) programming settings (atrial fibrillation atrial flutter with ventricular rate above the SVT limit); and (3) algorithm limitations (atrial tachycardia with ventricular rate around the shortest programmable SVT limit and SVT redetection following VT therapy). Programming measures improved detection ability 13 of 59 of inappropriately detected arrhythmias.

Conclusion. Dual chamber detection algorithms evaluated in subset of diagnostically difficult arrhythmias allow safe detection of double tachycardias but require further extension and programmability to improve VT:SVT discrimination rules (J Cardiovasc Electrophysiol. Vot. 11. pp. 1105‐1115. October 2000)
Laplacian Electrograms and the Interpretation of Complex Ventricular Activation Patterns During Ventricular Fibrillation
Authors: CORONEL RUBEN , WILMS‐SCHOPMAN FRANCIBN J.G , DE GROOT JORIS R. , JANSE MICHIEL J. , VAN CAPELLE FRANS J.L. , DE BAKKER JACQUES M.T.
Published: April 2007

Laplacian Electrograms and Ventricular Fihrillation. Introduction. During ventricular fibrillation (VF) interpretation of a local electrogram and determination of the local activation moment are hampered by remote activity or intervening repolarization waves. Successful defibrillation depends on critical timing of the shock relative to local activation. We tested the applicabillity of Laplacian electrograms for detection of the moment of local activation during VF.

Methods and Results. From isolated perfased porcine infact heart, 247 local unipolar electrograms were recorded simultaneously (13 × 19 matrix, interelectrode distance 0.3 mm) from the left ventricular wall during sinus rhythm, following pacing or during VF, Activation maps were constructed based on local unipolar electrograms, and Laplacian electrograms were calculated from local electrograms ane its eight neighbors. The Laplacian electrogram displayed a sharp R/S complex with local activation iodicted by the moment of zero crossing without interference from remote activity or repolarization waves. Its amplitude increased with decreasing interelectrode distance, Following epicardial stimulation, Laplacian amplitude was significantly larger than during complexes with different morphology. Collision of wavefronts was associated with entirely positive Laplacian waveforms; “focal” appearancce of acitivity was associated with an entirely negative waveform. Activation block in the activation maps was correlated with the appearance of substanined episodes of negativity or positivity in the Laplacian electrogram (depending on the location of the recording site relative to the line of block).

Conclusion. Laplacian electrograms allow detection of the moment of local activation without interference from remote activity or repolarization, especially during complex arrhythmias. The technique applied toe automatic sensing devices, such its the internal defibrillator, may optimize defibrtilation success. (J Cardiovasc Electrophysiol, Vol. 11, pp. 1119‐1128, October 2000)
Effects of Electrode‐Myocardial Separation on Cardiac Stimulation in Conductive Solution
Authors: KNISLEY STEPHEN B. , POLLARD ANDREW E. , EAST VLADIMIR G.
Published: April 2007

Electrode‐Myocardial Separation. Introduction. Effects of a conductive bath and electrodemyocardial separation on cardiac stimulation have not been elucidated. These factors may play a role in endocardial catheter stimulation or defibrillation.

Methods and Results. We studied effects of a bath and separation on transmembrane voltage changes during stimulation (ΔVm) and excitation thresholds in rabbit hearts, cultured rat cardiac cell monolayers and cardiac bidomain computer models. Similar to previous epicardial measurements with no bath, a dogbone pattern of ΔVm during stimulation was found in bathed epicardium and right ventricular septal endocardium and in models of bathed anisotropic myocardium. Electrode‐myocardial separation altered spatial distributions of ΔVm, moved reversals of the sign of ΔVm farther from the stimulation epicenter, and decreased aspect ratio of ΔVm (i.e., length/width of dogbone contours of ΔVm). The separation increased thresholds and reduced maximal ΔVm, while ΔVm at sites away from maxima increased or decreased. Anodal thresholds in models initially were larger than those in experiments and decreased when models were altered to include nonuniform cellular coupling. Existence of nonuniformity in monolayers was indicated by irregular excitation patterns.

Conclusion. Electrode‐myocardial separation alters spatial distributions of ΔVm, which may impact on arrhythmia induction by altering distributions of states of ΔVm‐sensitive ion channels. The results also indicate that excitation thresholds may depend on tissue nonuniformities. (J Cardiovasc Electrophysiol, Vol. 11. pp. 1132‐1143, October 2000)
Morphology of the Human Atrioventricular Node is Age Dependent: A Feature of Potential Clinical Significance
Authors: WAKI KENJI , KTM JUNG‐SUN , BECKER ANTON E.
Published: April 2007

AVN Morphology Related to Age. Introduction. Advances in catheter ablation procedures have created the need to understand better the morphology of the AV node (AVN), particularly as it relates to age.

Methods and Results. This study was based on 40 normally structured hearts obtained at autopsy from patients without a history of tachyarrhythmia in the following age ranges: <1 year (n = 19); 1‐12 years (n = 11); and 12‐20 years (n = 10). In 38 hearts, the AV septal junctional area was removed en bloc and serially sectioned at 10‐μm thickness at right angles to the AV annulus. The length of the compact node and the rightward and leftward inferlor extensions were calculated. Computer‐assisted three‐dimensional reconstructions were made of six hearts. The ratio of right extension to compact AVN showed a statistically significant increase with age; the increase in ratio of left extension to compact AVN was not statistically significant. In addition, with increasing age the geometry of the AVN changed from a half‐oval to a spindle shape, concomitant with development of a distinct so‐called muscular AV septum. The three‐dimensional reconstructions showed widening of the transitional cell zone with an increase in fibrofatty tissue related to age.

Conclusion. The AVN, inferlor extensions, and transitional cell zone show distinet age‐related changes that may be clinically relevant. The increase in length of the inferior extensions may set the scene for AVN reentry and could explain why this condition is more frequent in young adults than in infants. (J Cardioyasc Electrophysiol, Vol. 11, pp. 1144‐1151. October 2000)
Radiofrequency Ablation of Focal Atrial Tachycardia and Atrioatrial Conduction from Recipient to Donor after Orthotopic Heart Transplantation
Authors: STROHMER BERNHARD , CHEN PENG‐SHENG , HWANG CHUN
Published: April 2007

RF Ablation of Recipient‐to‐Donor Atrial Tachycardia. After cardiac transplantation, atrial arrhythmias may develop in the residual recipient atrium and conduct to the donor heart. Radiofrequency (RF) ablation of the atrioatrial conduction may be effictive in arrhythmia control, although the recipient atrium continues its tachycardia. We hypothesize that in patients with posttransplant atrial tachycardia, it is possible to ablate both the arrhythmogenic focus in the recipient atrium and the atrioatrial conduction. A 47‐year‐old patient who had orthotopic heart transplantation 9 months earlier underwent RF ablation procedure because of medically uncontrolled atrial arrhythmia. By conventional electrophysiologic mapping, we localized the locus of the atrial tachycardia in the recipient atrium and the electrical atrioatrial connection across the anastomotic suture line. Selective applications of RF energy eliminated both targets successfully. RF ablation of recipient atrial tachycardia and atrioatrial conduction from recipient to donor may lead to long‐term success of arrhythmia control.
Nonfluoroscopic Three‐Dimensional Mapping for Arrhythmia Ablation: Tool or Toy?
Authors: KHONGPHATTHANAYOTHIN APICHAI , KOSAR EROL , NADEMANEE KOONLAWEE
Published: April 2007

Arrhythmia Ahlation with Nonfluoroscopic 3D Mapping. Introduction: Conventional mapping and ablation rely on fluoroscopy, which can result in imprecise positioning of the ablation catheter and long fluoroscopic exposure times. We evaluated a nonfluoroscopic three‐dimensional mapping system, termed CARTO, and compared the results of ablation using this technique with those of conventional mapping.

Methods and Results: We compared the results of 88 arrhythmia ablations (79 patients) using CARTO with 100 ablations (94 patients) using the conventional technique. The ablations were separated into four groups: (1) AV nodal reentrant tachycardia (AVNRT); (2) atrial tachycardia/flutter; (3) ventricular tacbycardia (VT); and (4) bypass tract tachycardia. We compared the success rate, complications, and fluoroscopy and procedure times. Tbe ablation outcomes were excellent and comparable in all four types of the arrhythmias between the two techniques. Major complications included one cardiac tamponade in each group and one second‐degree AV block in the conventional group. Fluoroscopy time was shorter using the CARTO technique: 10 ± 7 versus 27 ± 15 minutes for AVNRT (P < 0.01), 18 ± 17 versus 44 ± 23 minutes for atrial tachycardia and flutter (P < 0.01), 15 ± 12 versus 34 ± 31 minutes for VT (P < 0.05), and 21 ± 14 versus 53 ± 32 minutes for bypass tract tachycardia (P < 0.01). Procedure times were similar except for the bypass tract patients, wbich was shorter in the CARTO group, 4 ± 1.3 versus 5.5 ± 2.5 hours (P < 0.01).

Conclusion: The electroanatomic three‐dimensional mapping technique reduced fluoroscopy time and resulted in excellent outcome without increasing the procedure time.
Role of Virtual Electrodes in Arrhythmogenesis: Pinwheel Experiment Revisited
Authors: LINDBLOM ANNETTE E. , ROTH BRADLEY J. , TRAYANOVA NATALIA A.
Published: April 2007

Virtual Electrodes in Arrhythmogenesis. Introduction: Recent experimental evidence demonstrates that a point stimulus generates a nonuniform distribution of transmembrane potential (virtual electrode pattern) consisting of large adjacent areas of depolarization and hyperpolarization. This simulation study focuses on the role of virtual electrodes in reentry induction.

Methods and Results: We simulated the electrical behavior of a sheet of myocardium using a two‐dimensional bidomain model with straight fibers. Membrane kinetics were represeuted by the Beeler‐Reuter Drouhard‐Roberge model. Simulations were conducted for equal and unequal anisotropy ratios. S1 wavefront was planar and propagated parallel or perpendicular to the fibers. S2 unipolar stimulus was catbodal or anodal. With regard to unequal anisotropy, for both cathodal and anodal stimuli, the S2 stimulus negatively polarizes some portion of membrane, deexciting it and opening an excitable pathway in a region of otherwise unexcitable tissue. Reentry is generated by break excitation of this tissue and subsequent propagation through deexcited and recovered areas of myocardium. Figure‐of‐eight and quatrefoil reentry are observed, with figure‐of‐eight most common. Figure‐of‐eight rotation is seen in the direction predicted by the critical point hypothesis. With regard to equal anisotropy, reentry was observed for cathodal stimuli only at strengths > ‐95 A/m.

Conclusion: The key to reentry induction is the close proximity of S2‐induced excited and deexcited areas, with adjacent nonexcited areas available for propagation.
Involvement of NF‐κB subunit p65 and retinoic acid receptors, RARα and RXRα, in transcriptional regulation of the human GnRH II gene
Authors: Hoo Ruby L. C. , Chan Kathy Y. Y. , Leung Francis K. Y. , Lee Leo T. O. , Leung Peter C. K. , Chow Billy K. C.
Published: April 2007

Gonadotropin‐releasing hormone (GnRH) I and II are hypothalamic decapeptides with pivotal roles in the development of reproductive competence and regulation of reproductive events. In this study, transcriptional regulation of the human GnRH II gene was investigated. By scanning mutation analysis coupled with transient promoter assays, the motif at −641/−636 (CATGCC, designated GII‐Sil) was identified as a repressor element. Mutation of this motif led to full restoration of promoter activity in TE671 medulloblastoma and JEG‐3 placenta choriocarcinoma cells. Supershift and chromatin immunoprecipitation assays showed in vitro and in vivo binding of NF‐κB subunit p65 and the retinoic acid receptors, RARα and RXRα, to the promoter sequences. Over‐expression of these protein factors indicated that p65 is a potent repressor, and the RARα/RXRα heterodimer is involved in the differential regulation of the GnRH II gene in neuronal and placental cells. This was confirmed by quantitative real‐time PCR. Treatment of cells with the RARα/RXRα ligands, all‐trans retinoic acid and 9‐cis‐retinoic acid, reduced and increased GnRH II gene expression in TE671 and JEG‐3 cells, respectively. Taken together, these data demonstrate the differential roles of NF‐κB p65 and RARα/RXRα, interacting with the same sequence in the promoter of the human GnRH II gene to influence gene expression in a cell‐specific manner.
Male reproductive allocation in fireflies (Photinus spp.)
Authors: Demary Kristian C. , Lewis Sara M.
Published: April 2007

Abstract. Resource allocation between somatic and reproductive structures has important fitness consequences for individuals, and optimal trade‐offs are expected to depend not only on mating system differences among species but also on levels of resource stress within species. We tested the prediction that polyandry (associated with increased sperm competition) will increase male reproductive allocation in bioluminescent fireflies in Photinus spp. by comparing the relative mass of testes, seminal vesicles, and reproductive accessory glands among a monandrous and several polyandrous species. In addition, we examined a single population of a polyandrous species, Photinus greeni, to see how reproductive allocation might shift between years in response to different levels of larval resource stress. As predicted, males of P. collustrans, a monandrous species, showed a fivefold lower allocation to sperm production and a 100‐fold lower allocation to reproductive accessory glands compared with males from polyandrous species. We also found evidence within P. greeni of a trade‐off between allocation either to reproduction or to somatic tissue; following larval resource stress, males eclosed at significantly shorter body lengths, yet showed a 35% increase in their reproductive allocation. These results demonstrate that mating systems strongly influence male allocation to reproductive accessory glands as well as to sperm production. Furthermore, these results suggest that under larval resource stress males of Photinus spp. increase their allocation to reproduction at the expense of somatic tissue, thus maximizing their ability to produce nuptial gifts required for reproductive success.
In vivo investigation of oocyte transit and maturation in a broadcast‐spawning holothurian
Authors: Hamel Jean‐François , Mercier Annie
Published: April 2007

Abstract. A sequential in vivo approach was used to examine the transformations undergone by oocytes during transit in the gonoduct of the sea cucumber Holothuria leucospilota, from ovulation until fertilization competency. Spasms of the ovarian muscle bands, during the pre‐spawning locomotor activity of the females, coincided with the extrusion of oocytes from the follicle cells (ovulation). No germinal vesicle breakdown (GVBD) was visible and the oocytes were not fertilizable. As the animal began to display the anterior sweeping movements characteristic of spawning, the oocytes streamed out of the gonad and were stored in the gonad basis. The oocytes, which were still non‐fertilizable, were then pressed forward through the first (proximal) section of the gonoduct. GVBD was completed during this rapid transit, but oocytes could not be fertilized unless they had soaked ≥20 min in seawater. In the second (distal) section of the gonoduct, most oocytes were readily fertilizable; fertilization rates increased noticeably after the formation of a bulge beneath the gonopore, which favored the entry of seawater. Hydration of the jelly coat was apparent (i.e., a 60% increase in oocyte surface area). Gamete release occurred in one powerful spurt ∼85 min after the onset of ovulation. This oocyte maturation sequence is expected to occur in holothurian species with similar anatomy and spawning behavior.
THE PUSH–PULL OF MARKETING AND ADVERTISING AND THE ALGEBRA OF THE CONSUMER'S MIND*
Authors: EWALD JEFF , MOSKOWITZ HOWARD
Published: April 2007

This article suggests that the relationship between a brand and a product is a virtuous circle—the brand frames expectations for a product execution; and the product experience either strengthens the brand perceptions or weakens them. Empirical evidence, based on a comprehensive database of scores collected across multiple conjoint studies, then confirms the hypothesis that different product attributes synergize, or interact, with different brand names.
MODELING CONSUMER INTENTION TO PURCHASE FRESH PRODUCE
Authors: DE SOUZA ELOIZA A.M. , MINIM VALÉRIA P.R. , MINIM LUIS A. , COIMBRA JANE S.R. , DA ROCHA RONEY A.
Published: April 2007

The effect of some fresh‐cut carrot label attributes on consumer purchase intention was evaluated using conjoint analysis. The following three attributes were chosen and manipulated: price (high and low), packaging type (polyethylene bags and expanded polystyrene trays) and production process (organic with certification stamp, organic without certification stamp and no information). A complete factorial design was used, and 12 hypothetical packages of fresh‐cut carrot were developed and evaluated by 96 consumers based on their purchase intention. The consumers were divided into four groups with different opinions. Low price and organic with certification label were the favorite choices of the groups. Only one group preferred expanded polystyrene trays. No interactions were exhibited among the attributes in all groups.