bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution of a Pacemaker Bradycardia Detection Algorithm in the Study of Patients with Carotid Sinus Syndrome
Authors: GRAUX PIERRE , GUYOMAR YVES , LEJEUNE CHRISTINE , CARLIOZ ROLAND , DURIEU CHRISTINE , DUTOIT ALBERT
Published: July 2003

GRAUX, P., et al.: Contribution of a Pacemaker Bradycardia Detection Algorithm in the Study of Patients with Carotid Sinus Syndrome. While carotid sinus syndrome (CSS) is often suspected as a cause of syncope in the elderly, whether it represents an indication for cardiac pacing may remain uncertain. Bradycardia algorithms included in pacemakers are now able to establish a precise relationship between spontaneous asystole and occurrence of symptoms and strengthen the indication for permanent pacing. This study included seven men and three women (70.5 ± 7.3 years of age) who, over an average period of 54.1 ± 17 months, had suffered from syncope (12.6 episodes/patient) and presyncope (11.2 episodes/patient) attributed to pure cardioinhibition (2 patients) or mixed CSS (8 patients). Other sources of symptoms were excluded by thorough clinical evaluations, including Holter monitoring, echocardiography, and electrophysiological testing. All patients received a CHORUS 6234 pacemaker, the memory of which includes a dedicated bradycardia detection algorithm capable of storing atrial and ventricular chains, and date and time of the last ten pauses and/or bradycardic events. After a initial period of 14.7 ± 8 months, during which symptoms were suppressed, the bradycardia algorithm was activated. From then on, a cumulative increase in the number of patients presenting with diurnal pauses was measured (1 month, n = 0; 3 months, n = 6; 9 months, n = 7; 2 years, n = 8). Fourteen episodes of diurnal asystole were recorded. The mean duration of the longest episodes of spontaneous ventricular standstill was 6,319 ± 1,615 ms and was due to sinoatrial block (n = 7), atrioventricular block (n = 5), and a combination of both (n = 2). In conclusion, activation of the CHORUS bradycardia algorithm allowed confirmation of the appropriateness of permanent pacing in a majority of patients suffering from CSS.
Radiofrequency Catheter Ablation Using Long Coiled Electrodes: Impact of Irrigation on Lesion Dimensions and Incidence of Coagulum Formation
Authors: WEISS CHRISTIAN , ANTZ MATTHIAS , THUNEKE FELIX , MEINERTZ THOMAS , KUCK KARL‐HEINZ , WILLEMS STEPHAN
Published: July 2003

WEISS, C., et al.: Radiofrequency Catheter Ablation Using Long Coiled Electrodes: Impact of Irrigation on Lesion Dimensions and Incidence of Coagulum Formation. Ablation catheters with multiple long coiled electrodes have been recently developed to induce continuous linear lesions for the treatment of atrial fibrillation. The efficacy and safety of ablation catheters with multiple long coiled electrodes has not been evaluated. The aim of the present in vivo study was to investigate the influence of saline irrigation on lesion dimensions and coagulum formation during RF current ablation using those ablation catheters. In 14 anesthetized sheep, the thigh muscle was prepared as a cradle and filled with heparinized blood (37°C). The quadripolar coiled ablation catheter (electrode length 7 mm, electrode distance 2 mm) was placed parallel to the muscle with standardized 10‐g contact pressure. RF current energy was delivered sequentially temperature‐ (70°C) or power‐controlled (10, 20, 30, or 40 W) with additional irrigation of the electrode (10 mL/min normal saline) for 90 seconds. Forty‐two of 129 RF current lesions were induced by temperature‐controlled and 87 by irrigated ablation. Except for three lesions following low energy irrigated application (10 W), all lesions were continuous. Significantly larger lesions following irrigated RF current applications were produced with a power output of 30 W (depth 0.74 ± 0.13 cm, width 0.78 ± 0.13 cm) and 40 W (depth 0.75 ± 0.16 cm, width 0.92 ± 0.28 cm) as compared to 20 W (depth 0.47 ± 0.13 cm, width 0.82 ± 0.22 cm). Coagulum formation adherent to the electrode was exclusively observed following 18 of 42 nonirrigated RF current ablations. In conclusion, irrigated coiled ablation electrodes induce continuous linear lesions with a power output of 20–40 W. The risk of coagulum formation at the coiled electrode can be avoided by irrigation.
Clinical Use of Permanent Pacemaker for Conversion of Intraatrial Reentry Tachycardia in Children
Authors: CHIU CHRISTINE C. , MCCRINDLE BRIAN W. , HAMILTON ROBERT M. , GRIFFITHS JEAN E. , GOW ROBERT M.
Published: July 2003

CHIU, C.C., et al.: Clinical Use of Permanent Pacemaker for Conversion of Intraatrial Reentry Tachycardia in Children. The use of the implanted atrial‐based pacemaker to overdrive postsurgical intraatrial reentry tachycardia (IART) was evaluated in a large group of pediatric patients over a 14‐year study period. The authors sought to determine the feasibility of this noninvasive technique in the management of this specialized population and to determine factors associated with successful conversion. They examined 128 manual overdrive attempts performed on 22 consecutive patients. There were 10 patients with post‐Fontan repair, 7 with post‐Mustard/Senning procedure, and 5 with miscellaneous lesion types. The number of IART episodes for overdrive pacing per patient ranged from 1 to 15. The first overdrive pacing attempt was successful in 63% (14/22) of the patients. The mean IART cycle length was 278 ± 59 ms. The mean pacing rate for effective conversion of IART was 66 ± 10% faster than the IART rate. By controlling for repeated measures for individual patients, three factors were found to be independently associated with a successful outcome: (1) lesion type other than Fontan surgery (P = 0.007), (2) lack of acceleration of IART with the overdrive attempt (P < 0.001), and (3) patient use of amiodarone with attempt (P = 0.005). There were three procedural complications: two inadvertent overdrive pacing episodes, and one episode of acceleration of IART cycle length and conduction resulting in need for cardioversion. Manual pacemaker overdrive conversion of IART is a useful adjunct in the management of postsurgical IART in the pediatric population and should be considered as an initial treatment option.
Clinical Evaluation of Morphology Discrimination: An Algorithm for Rhythm Discrimination in Cardioverter Defibrillators
Authors: BORIANI GIUSEPPE , BIFFI MAURO , FRABETTI LORENZO , LATTUCA J. JOHN , BRANZI ANGELO
Published: July 2003

BORIANI, G., et al.: Clinical Evaluation of Morphology Discrimination: An Algorithm for Rhythm Discrimination in Cardioverter Defibrillators. The aim of this study was to test the new morphology discrimination diagnostic algorithm for ICDs that differentiates supraventricular tachycardias (SVTs) from VTs by analysis of ventricular depolarization complexes morphology. Twenty‐five patients implanted with a St. Jude Ventritex single chamber ICD were studied during electrophysiological evaluation at pre‐discharge and were followed for 7 ± 4 months. Sensitivity and specificity for VT detection and overall diagnostic accuracy of the morphology discrimination algorithm were calculated on 326 detected events. At electrophysiological evaluation, the algorithm was tested during 67 episodes of right atrial pacing, during 119 episodes of RV pacing (at basal interventricular septum and RV apex) and during 27 episodes of sustained AF: specificity was 98%, sensitivity was 66%, and diagnostic accuracy was 80%. All episodes of AF were correctly diagnosed as SVT. Exclusion of detections related to pacing at the basal interventricular septum, resulted in a specificity of 98%, a sensitivity of 85%, and a diagnostic accuracy of 93%. During follow‐up, evaluation of the morphology discrimination algorithm on 113 spontaneous episodes (31 VTs, 31 AF, 7 SVTs, and 44 sinus tachycardias) exhibited a specificity of 89%, a sensitivity of 100%, and a diagnostic accuracy of 92%. In conclusion, the morphology discrimination algorithm exhibits a high specificity in discriminating VTs from SVTs, although with a corresponding reduction in sensitivity. The preliminary experience on spontaneous episodes is promising. To correct for the reduction in sensitivity, it is advisable to use this algorithm in parallel with other algorithms for rhythm discrimination (sudden onset, stability) coupled with extended high rate.
Transvenous Left Atrial and Left Ventricular Pacing in Ebstein's Anomaly with Severe Interatrial Conduction Block
Authors: GARRIGUE STEPHANE , BAROLD S. SERGE , HOCINI MELEZE , JAÏS PIERRE , HAÏSSAGUERRE MICHEL , CLEMENTY JACQUES
Published: July 2003

GARRIGUE, S., et al.: Transvenous Left Atrial and Left Ventricular Pacing in Ebstein's Anomaly with Severe Interatrial Conduction Block. The implantation of permanent pacemakers in patients with congenital heart disease can be challenging. This report describes the complexity of pacemaker implantation in a patient with Ebstein's disease, tricuspid valve replacement, and right atrial abnormalities like severe intra‐ and interatrial conduction block that prevented dual chamber pacing from conventional sites. This case illustrates the promising possibility to circumvent the interatrial conduction block with single left atrial pacing instead of biatrial pacing which was not suitable here.
Prospective Evaluation of Catheter Ablation in Patients with Implantable Cardioverter Defibrillators and Multiple Inappropriate ICD Therapies Due to Atrial Fibrillation and Type I Atrial Flutter
Authors: KORTE THOMAS , NIEHAUS MICHAEL , MEYER OLIVER , TEBBENJOHANNS JÜRGEN
Published: July 2003

KORTE, T., et al.: Prospective Evaluation of Catheter Ablation in Patients with Implantable Cardioverter Defibrillators and Multiple Inappropriate ICD Therapies Due to Atrial Fibrillation and Type I Atrial Flutter. The high incidence of inappropriate therapies due to drug refractory supraventricular tachycardia remains a major unsolved problem of the ICD. Most of the inappropriate therapies for supraventricular tachycardia are caused by AF and type I atrial flutter with rapid ventricular response. The purpose of this prospective study was to determine the usefulness of AVN modulation or ablation for rapid AF and ablation of the tricuspid annulus‐inferior vena cava (TA‐IVC) isthmus for type I atrial flutter in ICD patients with frequent inappropriate ICD interventions. Eighteen consecutive patients were enrolled in this study. Twelve patients received a mean of 34 ± 36 antitachycardia pacing (ATP) and 41 ± 32 shock therapies for rapid AF during 49 ± 39 months, and 6 patients a mean of 111 ± 200 ATP and 11 ± 8 shock therapies for type I atrial flutter during 52 ± 37 months preceding ablation procedure. Modification of the AVN was successful in 10 (83%) of 12 AF patients, in 2 (17%) patients ablation of the AVN was performed. A complete TA‐IVC isthmus block was achieved in 5 (83%) of 6 atrial flutter patients. Three (25%) AF patients had 11 ± 24 recurrences of ATP and 0.4 ± 1.1 shock therapies for rapid AF during 15 ± 7 months. None of the atrial flutter patients had recurrences of inappropriate therapies for type I atrial flutter during 14 ± 8 months, but two (33%) patients had inappropriate ICD therapies for type II atrial flutter or rapid AF. There was an overall mean incidence of 18 ± 22 inappropriate ICD therapies per 6 months before and 4 ± 9 per 6 months after the ablation procedure (P < 0.05). In conclusion, radiofrequency catheter modification or ablation of the AVN for rapid AF and ablation for atrial flutter type I are demonstrated to be highly effective in the majority of ICD patients with drug refractory multiple inappropriate ICD therapies.
Mapping the Organization of Atrial Fibrillation with Basket Catheters Part I: Validation of a Real‐Time Algorithm
Authors: BARBARO VINCENZO , BARTOLINI PIETRO , CALCAGNINI GIOVANNI , CENSI FEDERICA , MORELLI SANDRA , MICHELUCCI ANTONIO
Published: July 2003

BARBARO, V., et al.: Mapping the Organization of Atrial Fibrillation with Basket Catheters Part I: Validation of a Real‐Time Algorithm. The authors proposed a real‐time algorithm to quantify AF organization from multielectrode basket catheter (MBC) recordings. The algorithm is based on a fast method to estimate the number of points along the baseline of a single bipolar electrogram (number of occurrences, NO). They have already proven this parameter to be effective at discriminating AF organization according to Wells' criteria. Special attention has been paid to ventricular far‐field artifacts, as they proved they can significantly bias the degree of organization. To fulfill the constraints of a real‐time application, a ventricular blanking procedure was implemented and validated. Bipolar electrograms were obtained from MBC in the right atrium in 17 informed patients with chronic AF. The results of NO computations were displayed as three‐dimensional color‐coded maps of organization by interpolating the measurements obtained at the locations of catheter bipoles. The proposed method allows real‐time estimation of the organization of the atrial electrograms according to Wells' criteria. The estimation has a temporal resolution of 2 seconds, is robust to far‐field ventricular artifacts, and interpolates the data available to furnish a single global map of the entire atrium. Further studies devoted to the analysis of individual and common patterns of the regional distribution of AF organization are needed to assess the usefulness of this approach for electrophysiological studies and therapeutic applications.
Noninvasive Diagnosis of a Wide QRS Complex Tachycardia Mechanism by Programmed Atrial and Ventricular Stimulation Using a Dual Chamber Defibrillator
Authors: STICHERLING CHRISTIAN , MICHAUD GREGORY F.
Published: July 2003

STICHERLING, C., et al.: Noninvasive Diagnosis of a Wide QRS Complex Tachycardia Mechanism by Programmed Atrial and Ventricular Stimulation Using a Dual Chamber Defibrillator. Stored atrial and ventricular electrograms retrieved from dual chamber implantable defibrillators facilitate the diagnosis of arrhythmias. This case also illustrates the usefulness of programmed atrial and ventricular stimulation for noninvasive rhythm diagnosis in patients with a wide QRS tachycardia and an implantable defibrillator.
Effect of Procainamide on the Postrepolarization Refractoriness in Cardiac Muscle: Evaluation Using the Block Coupling Interval in the Artificial Isthmus Model in the Canine Right Atrium
Authors: YOSHIZAWA NAOTO , NIWANO SHINICHI , MORIGUCHI MASAHIKO
Published: July 2003

YOSHIZAWA, N., et al.: Effect of Procainamide on the Postrepolarization Refractoriness in Cardiac Muscle: Evaluation Using the Block Coupling Interval in the Artificial Isthmus Model in the Canine Right Atrium. The post‐repolarization refractoriness (PRR) is an important factor to determine the conduction block in cardiac muscle. Recently, we proposed the block coupling interval (BCI) as an useful electrophysiological index for evaluating the PRR. In the present study, the effect of procainamide on PRR was evaluated using the BCI and the effective refractory period (ERP). In five beagle dogs, radiofrequency linear ablation was performed on the right atrial surface parallel to the AV groove, forming an artificial isthmus (8–10 mm width and 15–20 mm length). Bipolar recordings were performed in the isthmus at a resolution of 1.2 mm and single extrastimuli with eight basic drive trains were delivered to cause conduction blocks in the isthmus. When a conduction block occurred, the recorded coupling interval at the recording site just proximal to the site of block was defined as BCI. At the site of the block, the ERP and duration of the monophasic action potential (MAP) at each drive cycle length was measured. The PRR was calculated using two different formulas: (1) [ERP – MAP] and (2) [BCI – MAP]. Procainamide was administrated intravenously at a dose of 15 mg/kg after the control study and the whole study protocol was repeated. The site of the block in an individual dog was always the same. BCI, ERP, and MAP were all shortened in accordance with the shortening of the basic drive cycle length, and the BCI was always the longest, ERP the middle, and the MAP was the shortest. The administration of procainamide prolonged each parameter, but the order of BCI > ERP > MAP remained unchanged. The PRR calculated as [BCI – MAP] was prolonged from 15 ± 10 ms to 29 ± 8 ms by the administration of procainamide (P = 0.048), but [ERP – MAP] was unchanged (8 ± 10 ms vs 8 ± 4 ms). In the conduction block model in the canine right atrium, procainamide prolonged the [BCI – MAP], but did not change the [ERP – MAP]. The procainamide effect of prolonging the PRR might be expressed better by the change in the BCI than the ERP.
Internal Low Energy Cardioversion of Atrial Fibrillation Using a Single Lead System: Comparison of a Left and Right Pulmonary Artery Catheter Approach
Authors: SCHMIEDER SEBASTIAN , SCHNEIDER MICHAEL A. E. , KARCH MARTIN R. , SCHMITT CLAUS
Published: July 2003

SCHMIEDER, S., et al.: Internal Low Energy Cardioversion of Atrial Fibrillation Using a Single Lead System: Comparison of a Left and Right Pulmonary Artery Catheter Approach. Internal cardioversion (ICV) has been demonstrated as an effective and safe method for restoring sinus rhythm in patients with AF. Recently, a new single lead system with a balloon‐guided cardioversion catheter was introduced. ICV was performed after advancing a 7.5 Fr catheter flow‐directed into the left or right pulmonary artery (PA, distal array, cathode). The proximal array (anode) was placed at the lateral RA wall. Synchronized shocks (3/3 ms biphasic impulse) were applied using a stepwise protocol (0.5, 3, 6, 9, 12, 15 J) until sinus rhythm was restored or maximum energy (15 J) was reached. Sixty‐five patients (mean age 58 ± 13 years) with acute and chronic AF were included. Sinus rhythm could be restored in 59 (91%) patients. Cardioversion success was 93% in the left PA compared to 86% in right PA. DFTs for the left and right PA approaches were 7.1 ± 4.0 J and 10.2 ± 4.0 J, respectively (P < 0.0001). It was significantly higher in patients with an AF history > 7 days (7.2 ± 4.1 J) than for those with a recent onset of AF (5.6 ± 4.1 J), P = 0.0012. Shock impedance differed for the left and right PA lead configuration (53 ± 11 vs 49 ± 13 Ω, P < 0.05). A right PA lead configuration is as effective compared to a left PA catheter approach when performing ICV for AF. ICV with a single lead system is safe and cardioversion success is comparable to other internal and external cardioversion techniques. In combination with hemodynamic monitoring, flow‐directed nonfluoroscopic catheter positioning is feasible and may serve as a valuable therapeutic and diagnostic tool in intensive care units.
Comparison of Two Diagnostic Algorithms for Regular Broad Complex Tachycardia by Decision Theory Analysis
Authors: LAU ERNEST W. , NG G. ANDRÉ
Published: July 2003

LAU, E.W., et al.: Comparison of Two Diagnostic Algorithms for Regular Broad Complex Tachycardia by Decision Theory Analysis. Sensitivity and specificity are two inversely related properties of a diagnostic test and it is often practically infeasible to secure a high value for both simultaneously. Decision theory analysis shows that the utility of a diagnostic test depends not only on its sensitivity and specificity but also on the prevalence of the intended target disorder: when prevalence is low, a high specificity is more important than a high sensitivity, whereas when prevalence is high, a high sensitivity is more important than a high specificity. The significance of this principle is illustrated by two popular algorithms for the electrocardiographic diagnosis of regular broad complex tachycardia (BCT), of which the two main differential diagnoses are ventricular tachycardia (VT) and supraventricular tachycardia with aberrant conduction (SVTAC). Brugada et al. focused on criteria highly specific for VT and used them to build a four‐step algorithm. In contrast, Griffith et al. first selected criteria highly sensitive for VT and then criteria highly specific for VT to build a simple two‐step algorithm. It can be objectively demonstrated that the Griffith algorithm is more efficient and effective than the Brugada algorithm in terms of clinching the final diagnosis and improving overall diagnostic accuracy. The main reason for this is that VT is more common than SVTAC as the cause of regular BCT, and the Griffith algorithm adhered to the aforementioned principle governing the choice between sensitivity and specificity according to prevalence in its design. The Griffith algorithm also embodies an additional important principle, namely, it is easier and more efficient to choose alternatively between criteria highly specific and highly sensitive for the intended target disorder than concentrating on just one or the other in designing a multiple‐step sequential diagnostic algorithm.
The Ablation of Atrial Fibrillation with the Loop Catheter Design: What We Have Learned From the Animal Model
Authors: AVITALL BOAZ , URBONAS ARVYDAS , URBONIENE DALIA , MALHOTRA VINAY , MILLARD SCOTT C. , BHARATI SAROJA
Published: July 2003

AVITALL, B., et al.: The Ablation of Atrial Fibrillation with the Loop Catheter Design: What We Have Learned From the Animal Model. Ablation of chronic atrial fibrillation (AF) with the use of transcutaneous catheter ablation is yet to become a clinical tool. This article summarizes the development of the technology and the technique for the ablation of AF that was tested on the rapidly paced AF dog model. The current ablation technology using the standard ablation technique used in humans is not suitable for the creation of transmural contiguous linear lesions, and such technology is subjecting the patient to the prolonged procedures with considerable risk of complication. The use of the loop catheter design or other designs of ablation technology, which is specifically targeted for the creation of linear lesions, should be developed if the catheter approach for the ablation of AF is to succeed. This article describes the data available for the loop catheter design that is currently undergoing human feasibility studies.
Inappropriate Shock Delivery Due to Ventricular Double Detection with a Biventricular Pacing Implantable Cardioverter Defibrillator
Authors: SCHREIECK JÜRGEN , ZRENNER BERNHARD , KOLB CHRISTOF , NDREPEPA GJIN , SCHMITT CLAUS
Published: July 2003

SCHREIECK, J., et al.: Inappropriate Shock Delivery Due to Ventricular Double Detection with a Biventricular Pacing Implantable Cardioverter Defibrillator. This report describes a patient with advanced heart failure, pronounced intraventricular conduction delay, and ventricular tachycardias who underwent implantation of a multisite pacing ICD. Pacing leads were placed in the right atrium, right ventricular apex, and to the left ventricular posterior wall via a coronary sinus vein. The system proved to have correct sensing and pacing function in an atrial synchronized biventricular pacing mode and an appropriate detection of ventricular fibrillation. However, 1 month after implantation the patient received an inappropriate shock delivery due to double detection of ventricular premature beats. The inherent detection problem of dual ventricular sensing is discussed.
Cardiac Leiomyosarcoma of the Right Atrium in a Teenager: Unusual Manifestation with a Lifetime History of Atrial Ectopic Tachycardia
Authors: GEHRMANN JOSEF , KEHL HANS G. , DIALLO RAIHANATOU , DEBUS VOLKER , VOGT JOHANNES
Published: July 2003

GEHRMANN, J., et al.: Cardiac Leiomyosarcoma of the Right Atrium in a Teenager: Unusual Manifestation with a Lifetime History of Atrial Ectopic Tachycardia. A 16‐year‐old girl presented with atrial fibrillation. Transesophageal echocardiography revealed a right atrial leiomyosarcoma. Her past medical history was remarkable for incessant atrial ectopic tachycardia (AET) beginning in early infancy and continuing throughout childhood and adolescence that was refractive to medical and nonpharmacological treatment. After combined surgical and medical therapy, normal sinus rhythm was restored and the patient is currently in complete remission with no recurrent symptoms or atrial arrhythmias at 31 months after surgery and 23 months after the discontinuation of chemotherapy. Atrial tachycardia may be the first, and for prolonged periods, the only manifestation of a cardiac tumor and should prompt thorough investigation of its underlying morphological substrate.
Unexpectedly High Defibrillation Thresholds in an Active Can Implantable Cardioverter Defibrillator System
Authors: Rao Arun , REYNOLDS DWIGHT W. , BECKMAN KAREN J.
Published: July 2003

RAO, A., et al.: Unexpectedly High Defibrillation Thresholds in an Active Can Implantable Cardioverter Defibrillator System. This case report describes a patient undergoing defibrillator generator replacement in whom the defibrillation thresholds were significantly higher with a can‐active system than with a non‐active can system.
Adaptive Filtering in Exercise High Resolution ECG as Applied to the Hypertrophic Cardiomyopathy
Authors: KEPSKI ROMAN , BUCHNER TEODOR , CYTOWSKI JERZY , MALECKA LONGINA , WALCZAK FRANK
Published: July 2003

KEPSKI, R., et al.: Adaptive Filtering in Exercise High Resolution ECG as Applied to the Hypertrophic Cardiomyopathy. The application of adaptive filtering to ECG signals has been investigated for many years. This study shows that the exercise high resolution ECG (HRECG) can also be processed successfully in a similar way. Two groups were included consisting of 20 healthy individuals and 24 patients with hypertrophic cardiomyopathy (HCM) . The HRECG parameters for both groups were similar (QRSdur: 107 ± 7 vs 114 ± 18 ms NS, LAS: 25 ± 8 vs 22 ± 6 ms NS). In the first step, the HRECG signal was acquired at rest to obtain the averaged reference pattern. The next step was associated with peak exercise in which one could calculate short duration averaging (∼ 30 beats) or apply adaptive filtering in which the exercise component (EC) was extracted. Exercise was performed in the supine position on a bicycle ergometer. The load of 50 W was incremented by 50‐W steps in 3‐minute intervals and the test was ended by fatigue. Signals were recorded in X, Y, and Z bipolar leads with a 20‐Hz high pass filter. The short time average QRS duration mostly was abbreviated in normal individuals in contrast to HCM patients in which ventricular activity prolonged with sensitivity, specificity, and negative and positive predictive values: 79%, 65%, 73%, and 72%, respectively. The adaptive recurrent filtration (ARF) after cutoff of the EC at the level of 70 ms (this level is the EC mean value of both groups) showed the following statistics: 63%, 90%, 88%, and 90%. The Student's t‐test as applied to the duration of EC allowed a statistically significant difference between normals and HCM patients (66 ± 4 vs 71 ± 6 ms, P < 0.0052) and between HCM patients with and without ventricular tachyarrhythmia and DS (74 ± 6 vs 69 ± 6 ms, P < 0.046).
A Randomized Study on the Effects of Pacemaker Programming to a Lower Output on Projected Pulse Generator Longevity
Authors: SCHUCHERT ANDREAS , MEINERTZ THOMAS ,   LOW OUTPUT PROGRAMMING (LOP) INVESTIGATORS
Published: July 2003

SCHUCHERT, A., et al.: A Randomized Study on the Effects of Pacemaker Programming to a Lower Output on Projected Pulse Generator Longevity. The programmability of cardiac pacemakers enables the physician at follow‐up to adjust the pacing pulse under consideration of the 100% safety margin with respect to the individual pacing threshold. The purpose of reducing the output is to prolong pacemaker longevity. The aims of this prospective, randomized trial were to compare the effects of nominal output versus a lower output on projected pacemaker longevity in single and dual chamber pacemakers. The secondary aim was to assess how many patients can be programmed to 2.5 V/0.4 ms instead of the nominal 3.5‐V setting with ≥ 100% safety margin. The patients received the same types of VVI or DDD pacemakers that were connected in the ventricle to the steroid‐eluting, high impedance pacing lead. At the 3‐month follow‐up, patients with ventricular pacing thresholds ≤ 0.15 ms at 2.5‐V pulse amplitude were randomized to 3.5 V or 2.5 V amplitude at 0.4‐ms pulse duration. Lead function and projected device longevity were assessed with the pacemaker's telemetry 6 and 12 months after implantation. Of patients implanted with a VVI pacemaker, at the 3‐month follow‐up, 3 patients had pacing thresholds > 0.15 ms at 2.5 V and 139 patients could be randomized. A reprogramming to a higher output was necessary in one patient. The mean percentage of ventricular pacing was about 40% throughout the study time. The programming to 2.5‐V output resulted in an insignificant increase of device longevity from 117.9 ± 18.7 months in the nominal group to 123.7 ± 11.9 months at the 12‐month follow‐up (P = 0.16). Of patients implanted with a DDD pacemaker, 166 patients underwent randomization. The mean percentage of ventricular pacing was 85% in the ventricle and 35% in the atrium. The 2.5‐V setting significantly prolonged pacemaker longevity from 98.1 ± 21.3 to 112.0 ± 13.6 months (P < 0.0001). In three (1%) patients a late increase of the pacing threshold was observed. Due to the low ventricular pacing thresholds, the 2.5‐V/0.4‐ms setting provided, 3 months after implantation, a ≥ 100% safety margin in 99% of the patients. Programming to a lower output slightly increased projected pacemaker longevity compared to the nominal 3.5‐V setting. Longevity increased for 5% in patients with single and for 14% in dual chamber pulse generators.
Electrocardiographic Diagnosis of Acute Myocardial Infarction in the Presence of Ventricular Paced Rhythm
Authors: KOCHIADAKIS GEORGE E. , KALEBOUBAS MICHAIL D. , IGOUMENIDIS NIKOS E. , SKALIDIS EMMANUEL I. , VARDAS PANOS E.
Published: July 2003

KOCHIADAKIS, G.E., et al.: Electrocardiographic Diagnosis of Acute Myocardial Infarction in the Presence of Ventricular Paced Rhythm. ST‐segment deviation was recently described as the only ECG finding that was useful in the diagnosis of acute myocardial infarction during right ventricular pacing. This report shows that the same sign may also indicate the amount of myocardium in jeopardy and the coronary artery responsible.
Successful Prevention of Recurrent Ventricular Fibrillation by Intravenous Isoproterenol in a Patient with Brugada Syndrome
Authors: TANAKA HIROKAZU , KINOSHITA OSAMU , UCHIKAWA SHINICHIROU , KASAI HIROKI , NAKAMURA MEGUMI , IZAWA ATSUSHI , YOKOSEKI OSAMU , KITABAYASHI HIROSHI , TAKAHASHI WATARU , YAZAKI YOSHIKAZU , WATANABE NOBORU , IMAMURA HIROSHI , KUBO KEISHI
Published: July 2003

TANAKA, H., et al.: Successful Prevention of Recurrent Ventricular Fibrillation by Intravenous Isoproterenol in a Patient with Brugada Syndrome. Intravenous administration of isoproterenol restored the ST‐segment configuration to nearly normal in the right precordial leads and completely prevented spontaneous VF attacks in a patient with Brugada syndrome. The formation of a Brugada‐type ECG has been attributed to the transmural dispersion of repolarization of the right ventricular epicardium and related to modulation of the autonomic nervous system. Our case may provide clues to the pathophysiological mechanism of this syndrome.
Correlation Between Defibrillation Shock Outcome and Coherence in Electrocardiograms
Authors: PATWARDHAN ABHIJIT , MOGHE SACHIN , WANG K E , WRIGHT HART , LEONELLI FABIO
Published: July 2003

PATWARDHAN, A., et al.: Correlation Between Defibrillation Shock Outcome and Coherence in Elec‐trocardiograms. Cycle periods in ECG during VF are correlated with periods of reentrant activation. The ECGs recorded from different locations on the thorax were contributed to from electrical activations within the heart in approximately inverse proportion of their distance from the recording sites. Similarity in cycle periods between ECGs recorded from two locations, therefore, can be used as an index of spatiotemporal similarity in the rate of activation. In the present study coherence was used, which is a mathematical function that measures the degree of similarity that two signals exhibit at specific cycle periods, to test if spatiotemporal similarity in cycle periods between pairs of orthogonal ECGs was correlated with defibrillation shock outcome. The authors estimated time‐varying coherence from orthogonal ECGs during 10 seconds of electrically induced VF, which was terminated with a defibrillation shock with a 50% probability of successful outcome. Defibrillation shocks were delivered between a coil electrode placed at the right ventricular apex and a subdermal patch electrode. Time‐varying coherencies between pairs of ECGs were estimated using an adaptive least mean square algorithm. Time‐coherence surfaces were integrated within a frequency region centered at the dominant frequency. Data were collected from ten dogs during 206 (48%) successful and 221 (52%) unsuccessful trials. The results showed that coherencies between the sagittal‐transverse pair were 10%‐15% higher (P < 0.05) for successful than unsuccessful trials. The correlation between coherence and defibrillation outcome suggests that more defibrillation shocks occurred when the degree of spatial similarity in the rate of activations was higher terminated VF, than those that occurred at other times. These results are consistent with a hypothesis, recently proposed by others, that more uniform activation within regions of the heart that receive low potential gradients during shock may increase the probability of successful defibrillation.
Ventricular Endocardial Right Bifocal Stimulation in the Treatment of Severe Dilated Cardiomyopathy Heart Failure with Wide QRS
Authors: PACHÓN JOSÉ C. , PACHÓN ENRIQUE I. , ALBORNOZ REMY N. , PACHÓN JUÁN C. , KORMANN DÉCIO S. , GIMENES VERA M. , MEDEIROS PAULO T. J. , SILVA MARCO A. D. , SOUSA JOSÉ E. M. R. , PAULISTA PAULO P. , SOUZA LUIZ C. B. , JATENE ADIB D.
Published: July 2003

PACHÓN, J.C., et al.: Ventricular Endocardial Right Bifocal Stimulation in the Treatment of the Severe Dilated Cardiomyopathy Heart Failure with Wide QRS. The QRS widening by ventricular conventional pacing impairs the systolic and diastolic functions and increases mitral regurgitation. The aim of this study was to compare conventional pacing to an alternative stimulation mode with a narrower QRS using two leads in the RV. Thirty‐nine (25 men, 14 women; mean age 60.1 ± 15.1 years) dilated cardiomyopathy patients (Chagas' disease [n = 17], coronariopathy [n = 9], AV ablation for tachycardiomyopathy [n = 3], and other [n = 10]) with cardiac failure (NYHA 3.1 ± 0.8), pacemaker indication, and chronic AV block (22 AF) had endocardial pacemaker implantations (27 Biotronik, 12 Guidant). Two RV leads (one septal, one conventional [RV apex] were connected, respectively, to the atrial and ventricular pacemaker plugs. After clinical stabilization they were studied under three stimulation modes in the same session: AAI (septal), VVI (conventional), and ventricular endocardial right bifocal stimulation (VERBS) (DDT/DVI/DDD = AV interval = 15/10 ms). In comparison to conventional pacing, VERBS increased ejection fraction (0.124), cardiac output (19.5%), and peak filling rate (31.0%), and decreased QRS duration (24.7%), left atrium area (11.9%), mitral regurgitation area (32.3%), the diastolic transmitral flow (E/A relation) (19.3%), and the propagation flow time (18.0%) from the mitral valve to the left ventricular apex (tE_col), (P < 0.05). The quality‐of‐life showed an impressive score reduction of 50.4%. The septal stimulation alone showed a less expressive benefit. In severe dilated cardiomyopathy with classic pacemaker indication, VERBS showed significantly better performance than the septal or the conventional stimulation alone. There was a good systolic and a remarkable diastolic improvement causing an important reduction in the quality‐of‐life score.
Incidence and Predictors of Pacemaker Dysfunction with Unipolar Ventricular Lead Configuration. Can We Identify Patients Who Benefit from Bipolar Electrodes?
Authors: WIEGAND UWE K. H. , BODE FRANK , BONNEMEIER HENDRIK , TÖLG RALPH , PETERS WERNER , KATUS HUGO A.
Published: July 2003

WIEGAND, U.K.H., et al.: Incidence and Predictors of Pacemaker Dysfunction with Unipolar Ventricular Lead Configuration. Can We Identify Patients Who Benefit from Bipolar Electrodes? Unipolar ventricular leads were implanted in a considerable percentage of pacemaker recipients. There is little information on incidence and risk factors for unipolar pacemaker dysfunction using modern lead designs. Included in a cross‐sectional analysis were 682 patients who fulfilled the following criteria: chronically implanted bipolar ventricular leads (> 1 year), intraoperative stimulation threshold < 1.0 V/0.5 ms, and potential amplitude > 6 mV. Incidences of chest wall stimulation (CWS) at an output of twice the amplitude threshold and of myopotential oversensing (MPO) at a sensitivity of half the sensing threshold were assessed. Energy (0.60 [0.72] vs 0.63 [0.81] μJ) and sensing thresholds (8.31 [3.18] mV vs 8.47 [3.47] mV) did not differ between uni‐ and bipolar modes. While all pacemakers worked properly during bipolar configuration, malfunctions were observed in 5.9% of patients during unipolar configuration (CWS = 1.9%, MPO = 4.2%). Patient age > 76 years (hazard ratio HR 8.2; P < 0.001), heart failure ≥ NYHA Class II (HR 3.8; P < 0.001), and an antiarrhythmic therapy with Class I or III drugs (HR 3.3; P = 0.002) were independently associated with the occurrence of unipolar pacemaker dysfunction. Use of steroid‐eluting leads reduced the probability of pacemaker dysfunction (HR 0.45; P = 0.03). Risk factors for unipolar ventricular pacemaker malfunction were higher age, heart failure, and antiarrhythmic drug therapy. Particularly in these patients, use of bipolar ventricular leads is beneficial.
Rise of Defibrillation Energy Requirement Under Carvedilol Therapy
Authors: MELICHERCIK JURAJ , GOEPFRICH MICHAEL , BREIDENBACH THOMAS , VON HODENBERG EBERHARD
Published: July 2003

MELICHERCIK, et al.: Rise of Defibrillation Energy Requirement Under Carvedilol Therapy. Carvedilol, a nonselective β1‐, β2‐adrenoreceptor blocking agent with α1‐adrenoreceptor blocking activity, is often prescribed as an adjunctive pharmacological therapy in patients who received an ICD. Despite the new ICD technology, concomitant antiarrhythmic therapy still represents the most important concern in patients with an ICD. As illustrated by this case, carvedilol may also increase the energy requirement for internal defibrillation.
Myocardium Extending from the Left Atrium onto the Pulmonary Veins: A Comparison Between Subjects with and Without Atrial Fibrillation
Authors: TAGAWA MINORU , HIGUCHI KOUTAROU , CHINUSHI MASAOMI , WASHIZUKA TAKASHI , USHIKI TATSUO , ISHIHARA NORIKO
Published: July 2003

TAGAWA, M., et al.: Myocardium Extending from the Left Atrium onto the Pulmonary Veins: A Comparison Between Subjects with and Without Atrial Fibrillation. Rapid discharges from the myocardium extending from the left atrium onto the pulmonary vein (PV) have been shown to initiate AF, and AF may be eradicated by the catheter ablation within the PV. However, if there is any difference in the distribution patterns of the myocardial sleeve onto the PV between the subjects with and without AF is to be determined. Twenty‐one autopsied hearts were examined. Eleven patients previously had AF before death and another 10 patients had normal sinus rhythm as confirmed from the medical records including ECGs before death. After exposing the heart, the distance to the peripheral end of the myocardium was measured from the PV‐atrial junction in each PV. Then, the PVs were sectioned and stained and the distal end of myocardium and the distribution pattern were studied. The anteroposterior diameter of the left atrium was also measured. In 74 of 84 PVs, the myocardium extended beyond the PV‐atrial junction. The myocardium was localized surrounding the vascular smooth muscle layer forming a myocardial sleeve. The peripheral end of the myocardial sleeve was irregular and the maximal and minimal distances were measured in each PV. The myocardium extended most distally in the superior PVs compared to the inferior ones and the maximal distance to the peripheral end was similar between the AF and non‐AF subjects (8.4 ± 2.8 vs 8.7 ± 4.4 mm for the left superior and 6.5 ± 3.5 vs 5.1 ± 3.9 mm for the right superior PV, respectively). A significant difference was found in the maximal distance in the inferior PVs: 7.3 ± 4.6 vs 3.3 ± 2.8 mm for the left (P < 0.05) and 5.7 ± 2.4 vs 1.7 ± 1.9 mm for the right inferior PV (P < 0.001) in the subjects with and without AF, respectively. The diameter of left atrium was slightly dilated in AF patients but insignificantly (4.1 ± 0.1 vs 3.6 ± 0.1 cm, P > 0.07). The myocytes on the PV were less uniform and surrounded by more fibrosis in patients with AF compared to those without AF. In conclusion, the myocardium extended beyond the atrium‐vein junction onto the PVs. The distribution patterns of the myocardium was almost similar between subjects with and without AF, but the histology suggested variable myocytes in size and fibrosis in patients with AF.
Internal Atrial Defibrillation During Electrophysiological Studies and Focal Atrial Fibrillation Ablation Procedures
Authors: KARCH MARTIN R. , SCHMIEDER SEBASTIAN , NDREPEPA GJIN , SCHNEIDER MICHAEL A.E. , ZRENNER BERNHARD , SCHMITT CLAUS
Published: July 2003

KARCH, M.R., et al.: Internal Atrial Defibrillation During Electrophysiological Studies and Focal Atrial Fibrillation Ablation Procedures. Induction of sustained AF during electrophysiological studies requires electrical cardioversion to restore sinus rhythm for continuation of the electrophysiological study and mapping procedure. The study included 104 consecutive patients (age 59 ± 12 years, 74 men), who were in stable sinus rhythm at the beginning of the electrophysiological study, underwent internal atrial defibrillation (IAD) of AF (> 15 minutes) that was induced during electrophysiological study. In 21 patients, AF was regarded to be the clinical problem (group I), and in the remaining 83 patients other arrhythmias represented the primary target of the electrophysiological study (group II). A 7.5 Fr cardioversion catheter (EP Medical) equipped with a distal array was used and placed in the left pulmonary artery and a proximal array of the same size was located along the lateral right atrial wall. All patients were successfully cardioverted with a mean energy of 6.2 ± 4.0 J. In 18 (78%) of 21 group I patients and in 12 (14%) of 81 group II patients, AF recurred 3.7 ± 3.4 and 2.4 ± 1.4 times during electrophysiological study, respectively. The IAD shock did not suppress focal activity, thus the mapping of atrial foci responsible for AF could be continued even after several IADs. No IAD related complications occurred during the study. In conclusion, (1) IAD can be safely and successfully performed during electrophysiological study without using narcotic drugs or high electric energies; (2) IAD does not suppress focal activity; and (3) even if AF recurs frequently during the electrophysiological study, IAD can be performed several times without significant time delay.
Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single Site and Biatrial Pacing
Authors: OGAWA MASAHIRO , SUYAMA KAZUHIRO , KURITA TAKASHI , SHIMIZU WATARU , MATSUO KIYOTAKA , TAGUCHI ATSUSHI , AIHARA NAOHIKO , KAMAKURA SHIRO , SHIMOMURA KATSURO
Published: July 2003

Ogawa, M., et al.: Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single site and Biabrial Pacing. It has been reported that atrial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS–d), or biatrial (simultaneous RAA and CS–d) pacing. In the AF group, AF inducibility was significantly higher with RAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS–d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS–d paced drive. The atrial recovery time (ART) at RAA and CS–d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS–d was calculated as the ART difference (ARTD). The ARTD was significantly longer during RAA pacing in the AF group than in control group (155.0 ± 32.8 vs 128.8 ± 32.9 ms, P < 0.05). In the AF group, ARTDs during biatrial (52.0 ± 24.2 ms) and CS–d pacing (51.7 ± 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS–d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS–d and biatrial pacing significantly reduced ARTD compared with RAA pacing.
Global Repolarization Sequence of the Ventricular Endocardium: Monophasic Action Potential Mapping in Swine and Humans
Authors: YUAN SHIWEN , KONGSTAD OLE , HERTERVIG EVA , HOLM MAGNUS , GRINS EDGARS , OLSSON BERTIL
Published: July 2003

YUAN, S., et al.: Global Repolarization Sequence of the Ventricular Endocardium: Monophasic Action Potential Mapping in Swine and Humans. The aim of this study was to evaluate the global sequence of repolarization over the ventricular endocardium. Disturbances in myocardial repolarization are associated with the genesis of arrhythmias. However, little is known about the global sequence of repolarization. Monophasic action potentials (MAPs) were recorded from 61 ± 18 LV and/or RV sites in ten healthy pigs and from 43 ± 15 LV or RV sites in eight patients using the CARTO system. Local activation time (AT), end‐of‐repolarization (EOR) time, and MAP duration were calculated and three‐dimensional global maps of AT, EOR, and MAP duration constructed. LV maps were obtained from all ten pigs and RV maps from three pigs. Five RV maps and five LV maps were obtained from the eight patients. (1) EOR sequence was recognizable in 12 of 13 pig maps and in all the patient maps. (2) EOR followed the sequence of activation in 12 of 13 pig maps and 8 of 10 patient maps. (3) The longest MAPs were recorded in or near the earliest activation area, and the shortest ones in or near the latest activation area in all the pig maps and in nine of ten and eight of ten patient maps, respectively. (4) In all maps, MAP duration and AT were negatively correlated, and EOR and AT positively correlated. In conclusion, repolarization gradients exist over the pig and the human ventricular endocardium. The activation sequence is a determinant for the repolarization sequence. The magnitude of the progressive MAP shortening with progressively later activation, relative to local AT, is a critical factor governing the direction and pattern of the EOR.