bluuebunny/crossref_metadata_2025 huggingface dataset:
Implantable Cardioverter Defibrillator Dysfunction During and After Magnetic Resonance Imaging
Authors: ANFINSEN OLE‐GUNNAR , BERNTSEN ROLF FRANCK , AASS HALFDAN , KONGSGAARD ERIK , AMLIE JAN PEDER
Published: July 2003

ANFINSEN, O.‐G., et al.: Implantable Cardioverter Defibrillator Dysfunction During and After Magnetic Resonance Imaging. This report describes a patient in whom a MRI of the brain was performed without realizing that an ICD had been implanted 8 days previously. Electromagnetic noise induced during the MRI was detected as ventricular fibrillation and nearly caused inappropriate shocks. Charge time during MRI was prolonged. The battery indicator switched to “end of life,” but this was reversed by capacitor reformation. These problems could have been avoided by inactivating the ICD prior to MRI. Three months later, the pacing threshold increased from 0.4 V per 0.5 ms at implantation to 2.8 V per 0.5. It is still uncertain whether radiofrequency current heating at the electrode tip caused the increased pacing threshold or if this would have occurred independently of the MRI. MRI of patients with an active ICD may cause life‐threatening complications, and it is unknown if MRI may be safely performed if the ICD is inactivated. Therefore, MRI of patients with an ICD remains contraindicated.
Long‐Term Follow‐Up Results of Tilt Training Therapy in Patients with Recurrent Neurocardiogenic Syncope
Authors: REYBROUCK TONY , HEIDBÜCHEL HEIN , VAN DE WERF FRANS , ECTOR HUGO
Published: July 2003

REYBROUCK, T., et al.: Long‐Term Follow‐Up Results of Tilt Training Therapy in Patients with Recurrent Neurocardiogenic Syncope. Tilt training therapy is considered as a first choice treatment for neurocardiogenic syncope in the Department of Cardiology, University of Leuven. However, long‐term compliance to therapy may be difficult when patients become asymptomatic. In a single center uncontrolled study, the long‐term clinical outcome of 38 patients was studied after a follow‐up period of 43 ± 7.8 months. At the time of assessment 29 patients had abandoned tilt training therapy, while 9 still continued on a regular basis. In this series, 31 (82%) of 38 patients were free from syncope and 25 (66%) of 38 were completely asymptomatic. During follow‐up, seven patients reported the recurrence of at least one syncope. Of these seven patients, six had discontinued tilt training therapy. The number of syncopes after discontinuation was significantly lower as compared with the period before initiation of tilt training. In only one patient syncope recurrence was observed during rather irregular tilt training therapy. Moreover, in 19 patients who abandoned tilt training after about 1 year, no syncope recurrence was reported during daily life, which suggests that the disturbed autonomic reflex activity in these patients may have been restored.
Application of Right Atrial Contiguous Linear Lesions: An In Vivo Efficacy Validation of Multipolar Ablation Catheters in an Animal Model
Authors: SCHNEIDER MICHAEL A. E. , NDREPEPA GJIN , VALLANT ANDRE , GAYK UTE , RICHTER THOMAS , HENKE JULIA , ZRENNER BERNHARD , KARCH MARTIN R. , ERHARDT WOLFGANG , SCHÖMIG ALBERT , SCHMITT CLAUS
Published: July 2003

SCHNEIDER, M.A.E., et al.: Application of Right Atrial Contiguous Linear Lesions: An In Vivo Efficacy Validation of Multipolar Ablation Catheters in an Animal Model. Catheter ablation of atrial flutter and catheter Maze procedures require the creation of linear lesions. The efficacy of different multipolar catheters to create linear contiguous transmural lesions was studied in a sheep model. In 19 sheep a multipolar ablation catheter was inserted into the right atrium. In nine sheep a steerable 7 Fr catheter (C1) with six 6‐mm electrodes and in five sheep a steerable 7 Fr catheter (C2) with four 5‐mm electrodes were placed. In five sheep a 3.7 Fr catheter (C3) with eight electrodes of 6‐mm length was deployed (steerable sheath). A total of 72 linear lesions were created and evaluated. Catheter types C1, C2, and C3 produced continuous lesions with at least two adjacent electrodes in 45%, 79%, and 87% of the lesions. The mean lesion length achieved by C3 was longer compared to C1 and C2 (27 ± 14 vs 10 ± 5 and 11 ± 6 mm; P < 0.05). The ability to produce contiguous lesions by all available electrodes was low: C1, 5%; C2, 5%; and C3, 6%. C3 was most effective in exerting transmural lesions (93% vs C1 75% and C2 57%; P < 0.0001). Microscopic endocardial fibrinous adhesions and macroscopic mild electrode carbonizations were caused by all catheter types. In conclusion, (1) all three catheter types do not create contiguous lesions along all electrodes. Gaps of viable tissue remain in most instances; (2) lesion depths and transmurality varies with different catheters; and (3) potentially hazardous thrombotic material was observed during radiofrequency ablation with all three catheters.
Atrial Premature Beats in Patients with Focal Atrial Fibrillation: Incidence at Baseline and Impact of Provocative Maneuvers
Authors: VENTURA RODOLFO , WEISS CHRISTIAN , WILLEMS STEPHAN , STURM NINA , KLEMM HANNO , MEINERTZ THOMAS
Published: July 2003

VENTURA, R., et al.: Atrial Premature Beats in Patients with Focal Atrial Fibrillation: Incidence at Baseline and Impact of Provocative Maneuvers. This study evaluated the incidence of atrial premature beats (APBs) and the impact of various provocative maneuvers in patients with focally initiated AF. Fifty patients (39 men, 57 ± 0.4 years) with focally initiated, paroxysmal AF underwent Holter recording and a standardized protocol of provocative maneuvers: vagomechanical stimulation, adenosine 12 mg IV, esmolol 500 ng/kg IV, orciprenaline IV 5 mg/50 mL saline 0.9%, and atropine 0.01 mg/kg IV A surface ECG was recorded for 20 minutes at baseline and following each part of the protocol. High focal activity was defined as ≥ 1 APB/minute. During Holter ECG, 29 (58%) patients had an amount of < 200 APBs, 12 (24%) patients < 700 ≥ 200, and 9 (18%) patients ≥ 700 APBs. Less than 1 hour of high focal activity was observed in 34 (68%) of the 50 patients. Before starting provocative maneuvers 15 (30%) patients had high focal activity whereas 35 (70%) presented < 1 APB/minute. In 29 (58%) patients APBs increased by ≥ 1/min during provocative maneuvers: by vagomechanical stimulation in 11 patients, after adenosine in 15, esmolol in 12, orciprenaline in 15, and after atropine in 9 patients. In all patients with ≥ 1 APB/min at baseline, focal activity decreased or disappeared during some single provocative maneuvers. AF occurred in eight patients under provocative maneuvers. No predictive factors of a successful provocative maneuver were detected with regard to the baseline patients characteristics and Holter results. In conclusion, patients with focally initiated AF have a low incidence of spontaneous APBs. Various provocative maneuvers successfully increase APBs in more than half of the patients; orciprenaline had the highest efficacy. Some provocative maneuvers may suppress APBs in the setting of high focal activity at baseline.
Estimation of Noise Level and Signal to Noise Ratio of Laplacian Electrocardiogram During Ventricular Depolarization and Repolarization
Authors: LIAN JIE , SRINIVASAN SRIRAM , TSAI HO‐CHIE , WU DONGSHENG , AVITALL BOAZ , HE BIN
Published: July 2003

LIAN, J., et al.: Estimation of Noise Level and Signal to Noise Ratio of Laplacian Electrocardiogram During Ventricular Depolarization and Repolarization. Body surface Laplacian ECG (LECG) has demonstrated its enhanced capability to localize cardiac electrical sources closest to the recording site. The aim of the present study was to evaluate the noise level and signal to noise ratio (SNR) in the LECG as compared to the potential ECG (PECG). Such evaluation is important to determine the applicability of the LECG to localizing and imaging of cardiac electrical activity in an experimental setting. Experimental studies were conducted in six healthy men. A 150‐channel PECG was recorded from the anterolateral chest and the LECG was estimated using the finite difference algorithm. The noise level in the PECG and LECG was evaluated using multiple estimation protocols. The signal level during ventricular depolarization and repolarization was also estimated, and the corresponding SNR was calculated. Different filtering techniques were examined to evaluate their effects on the noise level and SNR of the LECG and PECG. The experimental results indicate that with basic signal processing techniques (baseline adjustment, three‐point moving average filter, and Wiener spatial filter), the SNR of the LECG is about 30–40% of that of the PECG. Furthermore, the SNR estimated during ventricular depolarization is about three times that obtained during ventricular repolarization for the PECG and LECG. The present study indicates that the LECG derived from the PECG using a local finite difference estimation procedure has satisfactory SNR during the periods of ventricular depolarization and repolarization, and suggests the feasibility of estimating the LECG from the recorded PECG in human subjects in an experimental setting.
Inhibition of Biventricular Pacing by Far‐Field Left Atrial Activity Sensing: Case Report
Authors: OGUZ ENIS , AKYOL AHMET , OKMEN ERTAN
Published: July 2003

OGUZ, E., et al.: Inhibition of Biventricular Pacing by Far‐Field Left Atrial Activity Sensing: Case Report. This case report describes a patient with biventricular pacemaker in whom a far‐field sensing of left atrial activity by the pacemaker's ventricular channel resulted in ventricular pacing inhibition. Placing of the left ventricular pacing electrode in the proximal part of the coronary sinus tributary resulted in this far‐field sensing problem, which was resolved following decreasing the ventricular sensitivity. The authors suggest that the far‐field sensing of the left atrial activity should be kept in mind for troubleshooting of an atrio‐biventricular pacing system.
Usefulness of Atrial Pacing for Prevention and Termination of Atrial Tachyarrhythmias in a Patient with Persistent Atrial Fibrillation
Authors: ISRAEL CARSTEN W. , GRÖNEFELD GERIAN , LI YI‐GANG , HOHNLOSER STEFAN H.
Published: July 2003

ISRAEL, C.W., et al.: Usefulness of Atrial Pacing for Prevention and Termination of Atrial Tach‐yarrhythmias in a Patient with Persistent Atrial Fibrillation. Atrial pacing with dedicated algorithms for prevention and termination of atrial tachyarrhythmias is under clinical evaluation. A patient is described with persistent symptomatic AF. After cardioversion and implantation of a DDDRP pacemaker before planned AVN ablation, the patient was free of symptoms. Early after implant, one cardioversion of AF was necessary. Over the course of 12 months, only five episodes of atrial tachyarrhythmia occurred, all automatically pace terminated within 24 hours. Thus, selected patients with persistent AF may benefit from preventive atrial pacing since the tachyarrhythmia can organize intermittently to a degree sufficient for pace termination.
Macroreentrant Atrial Flutter Around a Common Atrioventricular Canal in an Infant with Complicated Congenital Heart Anomaly
Authors: SATOMI KAZUHIRO , SHIMIZU WATARU , SUYAMA KAZUHIRO , ECHIGO SHIGEYUKI , KAMAKURA SHIRO
Published: July 2003

SATOMI, K., et al.: Macroreentrant Atrial Flutter Around a Common Atrioventricular Canal in an Infant with Complicated Congenital Heart Anomaly. This report describes a 2‐year‐old male infant after repair of complicated congenital heart anomalies including common atrioventricular canal (CAVC), in which macroreentrant atrial flutter around the CAVC was demonstrated by electroanatomic mapping (CARTO) using a single catheter. Radiofrequency catheter ablation at the isthmus between the CAVC and the inferior vena cava eliminated the atrial flutter successfully.
Impact of Fusion Avoidance on Performance of the Automatic Threshold Tracking Feature in Dual Chamber Pacemakers: A Multicenter Prospective Randomized Study
Authors: CANDINAS RETO , LIU BO , LEAL JUAN , SPERZEL JOHANNES , FRÖHLIG GERD , SCHARF CHRISTOPH , DURU FIRAT , SCHÜLLER HANS
Published: July 2003

CANDINAS, R., et al.: Impact of Fusion Avoidance on Performance of the Automatic Threshold Tracking Feature in Dual Chamber Pacemakers: A Multicenter Prospective Randomized Study. The Autocapture algorithm enables automatic capture verification on a beat‐by‐beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty‐eight patients (mean age 69 ± 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24‐hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P < 0.001, 75% P < 0.01, 95% P < 0.01, and 94% P < 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P < 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.
Identification of Ventricular Tachycardia of Epicardial Origin from Unipolar Potentials Obtained at the Endocardial Surface: Is It Feasible?
Authors: LACROIX DOMINIQUE , KLUG DIDIER , MARQUIÉ CHRISTELLE , KOUAKAM CLAUDE , GRANDMOUGIN DANIEL , KACET SALEM
Published: July 2003

LACROIX, D., et al.: Identification of Ventricular Tachycardia of Epicardial Origin from Unipolar Potentials Obtained at the Endocardial Surface: Is It Feasible? VT late after myocardial infarction usually originates from the endocardial surface; subepicardial substrates are also possible. The identification of these atypical locations with endocardial mapping remains unresolved even with new mapping technologies. This study compared isopotential maps, signal morphology, and activation patterns around left endocardial breakthroughs recorded in VTs originating from the subepicardium or subendocardium after remote myocardial infarction. These results were extracted from a database of 111 tachycardias obtained at surgery in 34 patients. Mapping was performed with a 128‐unipolar electrode system using an epicardial mesh and a left ventricular endocardial balloon. Subepicardial (n = 7) and subendocardial VTs (n = 10) were defined as complete superficial reentry and/or as tachycardias with a ≥ 25‐ms delay between the earliest activity and the breakthrough of activation on the opposite surface. A positive potential distribution covering the area of initial endocardial activity was observed in a single subepicardial VT but in none of the subendocardial ones (P = NS). R waves were observed on the earliest endocardial unipolar signals in two subepicardial VTs and five subendocardial VTs (P = NS). The area covered by the first 5‐ms or 10‐ ms isochrone at the endocardial level was larger in subepicardial VTs than in subendocardial VTs but the difference was not significant. In conclusion, despite a wider endocardial area of early activity in VTs of subepicardial origin, no reliable criteria can be proposed to identify these tachycardias from mapping data restricted to the endocardial surface. This is probably due to highly nonuniform anisotropic propagation around the scarred tissue.
Frequent and Prolonged Asymptomatic Episodes of Paroxysmal Atrial Fibrillation Revealed by Automatic Long‐Term Event Recorders in Patients with a Negative 24‐Hour Holter
Authors: ROCHE FRÉDÉRIC , GASPOZ JEAN‐MICHEL , DA COSTA ANTOINE , ISAAZ KARL , DUVERNEY DAVID , PICHOT VINCENT , COSTES FRÉDÉRIC , LACOUR JEAN‐RENÉ , BARTHÉLÉMY JEAN‐CLAUDE
Published: July 2003

ROCHE, F., et al.: Frequent and Prolonged Asymptomatic Episodes of Paroxysmal Atrial Fibrillation Revealed by Automatic Long‐Term Event Recorders in Patients with a Negative 24‐Hour Holter. The presence, frequency, and duration of episodes of paroxysmal atrial fibrillation (PAF) is difficult to establish. This is caused by the limited duration of standard Holter recordings and to the unsatisfactory yield of patient‐triggered event recorders, because of asymptomatic events and of an inconsistent use of the patient dependent triggering function. A prospective cohort of 65 consecutive patients with recurrent palpitations and a negative 24‐hour ECG Holter was investigated by means of a cardiac event recorder bearing continuous automatic arrhythmia analysis and storage. Over a mean duration of 77 ± 36 hours, episodes of PAF were diagnosed in 20 (31%) patients, who had a total of 37 episodes; mean duration of PAF episodes was 7 hours 50 minutes ± 8/hours 45 minutes (minimum 45 minutes, maximum 28 hours). Eleven (55%) of these 20 patients were asymptomatic and would have remained undiagnosed without the automatic mode of the event recorder. Asymptomatic PAF episodes were longer than symptomatic ones (10 hours 30 minutes ± 6 hours 30 minutes vs 4 hours 50 minutes ± 4 hours, P < 0.05). In addition, episodes of sustained paroxysmal supraventricular tachycardia (PSVT) were diagnosed in 39 (57%) patients, of whom 34 (87%) were symptomatic. In this prospective cohort, a second standard 24‐hour monitoring would have missed 44% of the patients with PAF or PSVT and a classical patient‐triggered event recorder 13%. In patients still complaining of palpitations after one negative 24‐hour Holter, numerous, prolonged, and often asymptomatic episodes of PAF can be revealed by long‐term automatic event recorders. These devices should help clarify the clinical consequences of such episodes.
Automatic Discrimination Between Supraventricular and Ventricular Tachycardia Using a Multilayer Perceptron in Implantable Cardioverter Defibrillators
Authors: ROJO‐ÁLVAREZ JOSÉ L. , GARCÍA‐ALBEROLA ARCADI , ARENALMAÍZ ÁNGEL , PIÑEIRO‐AVE JOSÉ , VALDÉS‐CHAVARRI MARIANO , ARTÉS‐RODRÍGUEZ ANTONIO
Published: July 2003

ROJO‐ÁLVAREZ, J.L., et al.: Automatic Discrimination Between Supraventricular and Ventricular Tachycardia Using a Multilayer Perceptron in Implantable Cardioverter Defibrillators. The morphological analysis of implantable cardioverter defibrillator (ICD) stored electrograms (EGM) using a multilayer perceptron (MLP) has been proposed for discrimination between supraventricular and ventricular arrhythmias. However, a reliable estimation of the accuracy of MLP methods is lacking. The aim of the study was to compare the morphology and spectrum‐based MLP with more conventional morphology‐based algorithms in a large series of ICD‐stored episodes of arrhythmia. One set of ICD‐stored electrograms was used for control and training purposes and a second one, consisting of spontaneous episodes in patients with dual chamber ICDs, for validation of the MLP performance. The correlation waveform analysis (CWA) and the EGM width criterion were compared with MLP methods. Bootstrap resampling techniques were used to extract the relevant information in the MLP training. The morphology‐based MLP achieved better discrimination than any other method, with areas under the receiver operating characteristic (ROC) curve (tolerance intervals): 0.96 (0.81, 0.96) for MLP, 0.91 (0.77, 0.94) for CWA, and 0.68 (0.49, 0.78) for EGM width in the validation set. A specificity of 73.0% was obtained at 95% sensitivity, compared with 38.1% and 55.1% using CWA and EGM width criteria, respectively. In contrast, the generalization capabilities of spectral‐based MLP methods are poor, showing a lower area under the ROC curve in the validation set. Time‐domain MLP techniques may be useful for the morphological analysis of the intracardiac EGM signal stored by ICD devices. When properly trained and validated, these methods perform better than other commonly used morphological criteria for discrimination between supraventricular and ventricular arrhythmias.
The Incidence and Risk Factors for Venous Obstruction After Implantation of Transvenous Pacing Leads
Authors: OGINOSAWA YASUSHI , ABE HARUHIKO , NAKASHIMA YASUHIDE
Published: July 2003

OGINOSAWA, Y., et al.: The Incidence and Risk Factors For Venous Obstruction After Implantation of Transvenous Pacing Leads. Several investigators have shown that the incidence of venous obstruction after pacemaker implantation was observed in 31–50% of pacemaker patients. However, these previous reports did not investigate the venous system prior to implantation. The aim of this study was to determine the incidence and risk factors for venous obstruction in patients with transvenous pacing leads. The study included 131 consecutive patients (64 men, 67 women; mean age 71.3 ± 9.8 years) who were investigated using intravenous digital subtraction angiography (DSA) before and after permanent pacemaker implantation. Follow‐up DSA was performed for a mean interval of 44 ± 6 months after pacemaker lead implantation in 79 of 131 patients. A diameter narrowing > 60% was defined as an obstruction. Prior to implantation of pacing leads, venous obstruction was present in 18 (13.7%) of 131 patients. In 15 of these 18 patients, the obstruction was present at the site of the left innominate vein. Follow‐up DSA, after implantation of pacing leads, showed that venous obstruction was observed in 26 (32.9%) of 79 patients. There were no significant differences between obstruction and nonobstruction groups in terms of age, sex, cardiothoracic ratio, left atrial dimension, left ventricular ejection fraction, baseline heart diseases for indication of pacemaker implantation, or number and body size of pacing leads. Neither clinical symptoms nor abnormal physical findings were observed in any patients. In conclusion, the incidence of venous obstruction after pacing lead implantation is less than that of previous reports, which might be related to the incidence of venous obstruction before pacing leads implantation.
Percutaneous Treatment for Pacemaker‐Associated Superior Vena Cava Syndrome
Authors: CHAN ALBERT W. , BHATT DEEPAK L. , WILKOFF BRUCE L. , ROFFI MARCO , MUKHERJEE DEBABRATA , GRAY BRUCE H. , BAIZER CHRISTOPHER T. , YADAV JAY S.
Published: July 2003

CHAN, A.W., et al.:Percutaneous Treatment for Pacemaker‐Associated Superior Vena Cava Syndrome. Superior vena cava (SVC) obstruction is an uncommon but serious complication associated with permanent pacemaker implantation. The mechanical stress associated with pacemaker wires may lead to vessel wall inflammation, fibrosis, and thrombus formation, and ultimately to venous stenosis and occlusion. The surgical treatment of pacemaker related SVC syndrome requires thoracotomy and carries significant morbidity. This article illustrates the authors' initial experience with a “one‐step” percutaneous approach for this problem, consisting of percutaneous retrieval of a pacemaker system, followed by venous revascularization with angioplasty and stenting, and installation of a new pacemaker device.
Induction of Ventricular Fibrillation in Brugada Syndrome by Site‐Specific Right Ventricular Premature Depolarization
Authors: CHINUSHI MASAOMI , WASHIZUKA TAKASHI , CHINUSHI YUKO , HIGUCHI KOTAROU , TOIDA TATUNARI , AIZAWA YOSHIFUSA
Published: July 2003

CHINUSHI, M., et al.: Induction of Ventricular Fibrillation in Brugada Syndrome by Site‐Specific Right Ventricular Premature Depolarization. This patient was a 50‐year‐old man. Oral pilsicainide unmasked a Brugada‐type ECG abnormality and self‐terminating polymorphic VT was repetitively induced. The polymorphic VT always developed following a specific ventricular premature complex showing a left bundle branch block pattern suggesting a limited origin in the right ventricle.
Migration and Infection of a Pace‐Sense Lead from an Abdominal Defibrillator System
Authors: KHOO MICHELLE S.C. , SCHOLL FRANK , DIGNAN REBECCA , ROTTMAN JEFFREY N.
Published: July 2003

KHOO, M.S.C., et al.: Migration and Infection of a Pace‐Sense Lead from an Abdominal Defibrillator System. A 47‐year‐old man had an ICD system with epicardial and endocardial components and an abdominal generator placed in 1990 following a cardiac arrest. Ten years later his BT10 lead was amputated due to an insulation defect, and he received a new pectoral generator with transvenous leads. A few months later he developed fevers, chills, and bacteremia. Evaluation demonstrated migration of the entire BT10 lead into the right atrium. Complete surgical explantation was required and the bacteremia resolved. This case illustrates the importance of solid anchoring of distal lead components following generator removal and the potential complication of intravascular lead migration.
Brugada Syndrome Unmasked By Febrile Illness
Authors: KUM LEO C.C. , FUNG JEFFERY W.H. , SANDERSON JOHN E.
Published: July 2003

KUM, L.C.C., et al.: Brugada Syndrome Unmasked By Febrile Illness. The ionic mechanisms responsible for the electrocardiographic phenotype of the Brugada syndrome are temperature dependent. This report describes a healthy young man with ECG changes typical of Brugada syndrome that were unmasked during a febrile illness.
Rate Responsive Pacing Using Transthoracic Impedance Minute Ventilation Sensors: A Multicenter Study on Calibration Stability
Authors: DURU FIRAT , CHO YONG , WILKOFF BRUCE L. , COLE CHRISTOPHER R. , ADLER STUART , JENSEN DONALD N. , STROBEL ULLA , RADICKE DIRK , CANDINAS RETO
Published: July 2003

DURU, F., et al.: Rate Responsive Pacing Using Transthoracic Impedance Minute Ventilation Sensors: A Multicenter Study on Calibration Stability. Previous studies showed that transthoracic impedance. Previous studies showed that transthoracic impedance minute ventilation (IMV), as measured by a pacemaker sensor, is closely correlated to actual minute ventilation (VE·) determined by standard methods. The aim of this study was to analyze the changes in the calibration between IMV and VE· at rest and during exercise over time. Fifteen patients (age 60 ± 13 years) with Medtronic Kappa 400 pacemakers completed a baseline visit followed by two visits separated by 1 month and 1 week, respectively. In each patient, VE· (L/min) was monitored at rest in the supine and sitting positions and during graded bicycle ergometer exercise using a standard cardiopulmonary metabolic gas analysis system with simultaneous recording of IMV (Ω/min) using DR‐180 extended telemetry monitors. Calibration at rest was defined as the ratio of IMV to VE·, calculated from 1‐minute average values in the supine and sitting positions. Calibration during bicycle exercise was defined as intercept (IMV value at VE·= 10 L/min‐typical VE· value at beginning of exercise), and slope of the IMV/VE· regression line. The calibration of IMV showed individual variability over time. The magnitude (absolute value) of observed fractional changes in calibration at 1 month was 0.23 ± 0.20 (rest‐supine), 0.20 ± 0.15 (rest‐sitting), 0.18 ± 0.19 (exercise‐intercept), 0.28 ± 0.35 (exercise‐slope), and 0.18 ± 0.15, 0.15 ± 0.09, 0.28 ± 0.39, and 0.27 ± 0.15, respectively, at 1 week. The magnitude of change at 1 month was not statistically different from the magnitude of change at 1 week. In conclusion, the calibration of IMV, as measured by a pacemaker sensor, versus actual VE· may demonstrate variability. However, this study also suggests that the observed changes are not cumulative over time. These results have implications for patient monitoring applications using these sensors and for development of future pacemaker rate response algorithms.
Pacemaker Therapy in Isolated Congenital Complete Atrioventricular Block
Authors: BREUR JOHANNES M.P.J. , UDINK Ten Cate FLORIS E.A. , KAPUSTA LIVIA , COHEN MITCHELL I. , CROSSON JANE E. , BORAMANAND NICOLE , LUBBERS LOUISE J. , FRIEDMAN ALAN H. , BRENNER JOEL I. , VETTER VICTORIA L. , SREERAM NARAYANSWAMI , MEIJBOOM ERIK J.
Published: July 2003

BREUR, J.M.P.J., et al.: Pacemaker Therapy in Isolated Congenital Complete Atrioventricular Block. The aim of this study was to evaluate the effect of pacemaker (PM) therapy in patients with isolated congenital complete atrioventricular block (CCAVB). Patients with CCAVB eventually qualify for PM implantation, however, timing remains controversial. Retrospective evaluation of left ventricular end‐diastolic diameter (LVEDD), shortening fraction (SF), and cardiothoracic ratio (CTR) in 149 CCAVB patients, before, at, and after PM implantation was carried out. LVEDD shows an average increase of 0.48%/month in non‐PM patients, and an average decrease of 0.88%/month in PM patients. SF shows an average increase of 0.10%/month in non‐PM, and an average decrease of 0.32%/month in PM patients. CTR shows an average increase of 0.02%/month in non‐PM, and an average decrease of 0.19%/month in PM patients. The difference between the non‐PM and PM groups is significant (P = 0.05) for all variables. Symptomatic patients show no significant change in LVEDD after PM therapy (from 66.5% before to 68.5% after PM therapy). Asymptomatic patients do show a significant (P < 0.001) decrease in LVEDD after PM therapy (from 78.4% before to 73.3% after PM therapy). CTR does not differ significantly between symptomatic and asymptomatic patients before PM therapy (58% and 57%, respectively). CTR does differ significantly (P < 0.001) between symptomatic and asymptomatic patients after PM therapy (52% and 48%, respectively). Heart size and SF are increased in most patients with isolated CCAVB. PM implantation is associated with a decrease in heart size and normalization of SF in most patients. Indications for PM therapy in children may require reevaluation in asymptomatic patients with increased cardiac size and decreased cardiac function.
Upgrade of Permanent Pacemakers and Single Chamber Implantable Cardioverter Defibrillators to Pectoral Dual Chamber Implantable Cardioverter Defibrillators: Indications, Surgical Approach, and Long‐Term Clinical Results
Authors: SWEENEY MICHAEL O. , SHEA JULIE B. , ELLISON KRISTIN E.
Published: July 2003

SWEENEY, M.O., et al.: Upgrade of Permanent Pacemakers and Single Chamber Implantable Cardioverter Defibrillators to Pectoral Dual Chamber Implantable Cardioverter Defibrillators: Indications, Surgical Approach, and Long‐Term Clinical Results. The aim of this study was to describe the indications for upgrade of pacemakers (PMs) or single chamber (VVIR) ICDs to dual chamber (DDDR) ICDs, surgical approach, hardware hybridization, and clinical outcome. Patients with preexisting PMs or VVIR ICDs may develop indications for ICD therapy or dual chamber pacing, respectively, that can be served by DDDR ICDs that incorporate preexisting transvenous leads. Fifty‐seven patients underwent upgrade from PMs (29/57) or VVIR ICDs (28/57) to pectoral DDDR ICDs. Preexisting transvenous atrial and/or ventricular leads suitable for continued use were incorporated into new DDDR ICDs in 88.5% and 100% of PM and VVIR ICD upgrades, respectively. Acceptable DFTs were achieved in 56 (98.2%) of 57 patients. Appropriate VT/VF therapies were registered among 33.3% of patients during follow‐up. No shocks due to lead noise were observed in any patient with hybridized transvenous leads. Atrial far‐field R wave (FFRW) over‐sensing occurred in 24% of DDDR ICD systems incorporating a preexisting atrial lead. FFRW was overcome by programming reduced atrial sensitivity without interfering with the normal ICD system performance in all instances. Upgrade of PMs and VVIR ICDs to pectoral DDDR ICDs is safe and technically feasible in most patients. Preexisting transvenous leads can be successfully incorporated into new DDDR ICDs, simplifying the surgical procedure, minimizing transvenous hardware, and eliminating the possibility of hazardous pacemaker‐ICD interactions.
Continuous Holter Telemetry of Atrial Electrograms and Marker Annotations Using a Common Holter Recording System: Impact on Holter Electrocardiogram Interpretation in Patients with Dual Chamber Pacemakers
Authors: WIEGAND UWE K.H. , BONNEMEIER HENDRIK , BODE FRANK , EBERHARDT FRANK , CHUN JULIAN K.R. , KATUS HUGO A. , PETERS WERNER
Published: July 2003

WIEGAND, U.K.H., et al.: Continuous Holter Telemetry of Atrial Electrograms and Marker Annotations Using a Common Holter Recording System: Impact on Holter Electrocardiogram Interpretation in Patients with Dual Chamber Pacemakers. The impact of continuous telemetry of atrial electrogram and marker annotations on Holter ECG interpretation was assessed in 98 patients with bipolar dual chamber pacemakers (VDD pacemakers n = 29, DDD(R) systems n = 69). Atrial electrogram and marker annotations were continuously sampled by a telemetry coil that was externally positioned on the pacemaker pocket, amplified, and transduced to a three‐channel Holter ECG recorder in addition to an ECG recording. Holter tapes were analyzed by two experienced investigators for quality of P wave recognition and episodes suspicious of pacemaker dysfunction. Initially, only the ECG channel was analyzed. Thereafter, results were compared to those achieved on the basis of the complete recording including atrial electrogram and marker annotations. Recognition of atrial rhythm was markedly improved by Holter telemetry. During 99.3% of recording time telemetry showed a satisfying quality, whereas ECG alone allowed a reliable P wave recognition only during 84.4% of recording time (P < 0.001). One hundred twenty‐nine episodes suspicious of pacemaker malfunction occurred in 17 of 98 patients. By analysis of ECG, only 78.3% of episodes were concordantly classified by the investigators. However, 98.4% of all episodes were properly identified when atrial electrogram and marker annotations were added to the analysis (P < 0.001). In particular, discrimination between atrial undersensing, sinus bradycardia, and atrial sensed events within the refractory periods was facilitated. Holter telemetry of atrial electrogram and marker annotations facilitates the analysis of Holter ECGs in pacemaker recipients and improves the detection of pacemaker dysfunctions.
Hemodynamic Effect of the Ventricular Pacing Site in Fetal Lambs with Complete Atrioventricular Block
Authors: SHIRAISHI HIROHIKO , KIKUCHI YUTAKA , HOSHINA MASARU , OHKI TAKEHIRO , AYUSTAWATI  , MOMOI MARIKO Y.
Published: July 2003

SHIRAISHI, H., et al. Hemodynamic Effect of the Ventricular Pacing Site in Fetal Lambs with Complete Atrioventricular Block. Complete atrioventricular (AV) block in hydrops fetalis is associated with high mortality. Fetal ventricular pacing to restore ventricular rate can be an effective procedure, however, no fetal data has shown an appropriate epicardial ventricular pacing site. To evaluate the hemodynamic effect of right and left ventricular pacing in fetal lambs with complete AV block, a fetal complete AV block model was created. Aortic pressure, central venous pressure, and QRS duration were measured, and right and left ventricular output was estimated in seven fetal lambs. The uterus was opened under maternal anesthesia, and under local anesthesia, catheters were inserted into the fetal superior vena cava and ascending aorta through a neck incision. Pacing leads were then sutured onto the fetal right and left ventricular epicardium via a midline thoracotomy. Complete AV block was created by cryoablation of the AV node. Ventricular output was estimated using echocardiography by a transuterine approach. Fetal hemodynamics were observed before AV block creation (control), and after complete AV block creation with the right and left ventricular pacing set at 150/min. The right ventricular output was 320 ± 66 mL/kg per minute at control, decreased to 243 ± 65 mL/kg per minute during right ventricular pacing (P < 0.05), and was 254 ± 61 mL/kg per minute during left ventricular pacing. The left ventricular output was 224 ± 98 mL/kg per minute at control, 176 ± 77 mL/kg minute during right ventricular pacing, and 178 ± 67 mL/kg per minute during left ventricular pacing. Biventricular (combined ventricular) output was 544 ± 134 mL/kg per minute at control, 419 ± 114 mL/kg per minute during right ventricular pacing, and 432 ± 100 mL/kg minute during left ventricular pacing. Systolic aortic pressure was 62.2 ± 8.7 mmHg at control, 55.2 ± 9.5 mmHg during right ventricular pacing, and 53.4 ± 9.1 mmHg during left ventricular pacing. Central venous pressure (CVP) was 2.6 ± 0.5 mmHg at control, 4.0 ± 2.7 mmHg during right ventricular pacing, and 4.4 ± 2.5 mmHg during left ventricular pacing. The QRS duration was 51 ± 54 ms at control, but lengthened to 87 ± 19 ms during right ventricular pacing and to 78 ± 21 ms during left ventricular pacing (P < 0.05). In conclusion, the right ventricular output decreased during right ventricular pacing in fetal lambs with complete AV block, while it was preserved during the left ventricular pacing. Left ventricular pacing might be superior for treating hydropic fetuses with complete AV block.
Bleeding and Thromboembolic Risks of Internal Cardioversion for Persistent Atrial Fibrillation
Authors: TSE HUNG‐FAT , LAU CHU‐PAK
Published: July 2003

TSE, H.‐F., et al.: Bleeding and Thromboembolic Risks of Internal Cardioversion for Persistent Atrial Fibrillation. Although internal cardioversion is an effective method for converting AF the thromboembolic risk and bleeding complication of this procedure remains unclear. Retrospective analysis of the thromboembolic events and bleeding complications was performed in 114 consecutive patients (mean age 63 ± 10 years, 91 men) who underwent internal cardioversion for persistent AF (mean AF duration 31 ± 42 months). All patients received therapeutic warfarin for 3 weeks prior to the procedure, which was then replaced by periprocedural heparin therapy during internal cardioversion. The mean INR value before the internal cardioversion was 1.3 ± 0.2. A total of 992 R wave synchronized shocks were delivered (mean 8.7 shocks/patients) without ventricular proarrhythmia. Successful internal cardioversion of AF was achieved in 100 (88%) patients. Two (2%) patients developed major bleeding complications with pericardial effusion after the procedure. Both of them subsided with conservative treatment. Minor bleeding with wound hematoma occurred in 8 (7%) of 114 after the procedure. Overall, there was no significant difference in the risk of procedure related complication between the use of heparin infusion and subcutaneous LMWH injection (6/78 [13%] vs 3/36 [8%], P = 0.9). No thromboembolic event was observed after 4 weeks of follow‐up. In conclusion, the risk of thromboembolism after discontinuation of anticoagulation before the procedure is low in patients with persistent AF underwent internal cardioversion. However, the use of periprocedural heparin therapy was associated with an increase risk of procedure related bleeding complications.
Radiofrequency Catheter Ablation of Atypical Atrial Flutter Masquerading as Atrial Fibrillation
Authors: DYRUD MARTINUS , SHELLABERGER HOWARD , NAWMAN ROSELLA , WEST GAIL , KUSUMOTO FRED M.
Published: July 2003

DYRUD, M., et al.: Radiofrequency Catheter Ablation of Atypical Atrial Flutter Masquerading as Atrial Fibrillation. A patient with a surgically repaired double outlet right ventricle developed AF 6 months after successful RF catheter ablation of typical atrial flutter. Guided by a 64‐electrode basket catheter, the patient's AF was found to be dependent on an atypical atrial flutter circuit rotating around the fossa ovalis. Successful RF catheter ablation was performed by creating a line of conduction block from the superior vena cava to the fossa ovalis.
Treatment of Superior Vena Caval Obstruction Following Permanent Pacemaker Extraction
Authors: NEWALL NICK , STABLES ROD , PALMER NICK , RAMSDALE DAVID
Published: July 2003

NEWALL, N., et al.: Treatment of Superior Vena Caval Obstruction Following Permanent Pacemaker Extraction. Superior vena caval (SVC) obstruction following permanent pacemaker lead extraction is a serious but uncommon complication. This report describes the case of an 83‐year‐old man treated by balloon angioplasty and femoral pacemaker implantation.
Permanent Transfemoral Pacemaker Implantation in a Child with Maroteaux Lamy Syndrome
Authors: DILBER EMBIYA , CELIKER ALPAY , KARAGÖZ TEVFIK , KALKANOĞLU H. SERAP
Published: July 2003

DILBER, E., et al.: Permanent Transfemoral Pacemaker Implantation in a Child with Maroteaux Lamy Syndrome. Permanent transfemoral pacing has been described as an alternative route in patients in whom the superior venous approach is not feasible. This report describes the use of the femoral venous approach to insert a permanent pacemaker in a child with Maroteaux Lamy syndrome who has complete atrioventricular block and abnormal subclavian venous anatomy. Transfemoral pacing may be a suitable alternative in children with short stature.
Bidirectional Tachycardia Eliminated with Radiofrequency Ablation
Authors: LI JIAN‐MING , WELCH PATRICK J. , ZAGRODZKY JASON D. , HAMDAN MOHAMED H.
Published: July 2003

LI, J.‐M., et al.: Bidirectional Tachycardia Eliminated with Radiofrequency Ablation. This report describes an unusual case of bidirectional tachycardia eliminated with radiofrequency ablation. The tachycardia had alternating right and left bundle branch block morphology on a beat‐to‐beat basis and was successfully eliminated by ablating the right and left bundle branch block ventricular ectopic beats present during sinus rhythm.
Cardiac Vein Angioplasty for Biventricular Pacing
Authors: SANDLER DAVID A. , FEIGENBLUM DAVID Y. , BERNSTEIN NEIL E. , HOLMES DOUGLAS S. , CHINITZ LARRY A.
Published: July 2003

SANDLER, D.A., et al.; Cardiac Vein Angioplasty for Biventricular Pacing. Biventricular pacing for the treatment of congestive heart failure has consistently demonstrated improvement in quality‐of‐life and reduction in heart failure symptoms. Though the over‐the‐wire systems will be helpful in overcoming many existing obstacles to optimal lead placement, anatomic variability will still limit overall success. Cardiac vein angioplasty may be required for deployment of leads into tortuous or obstructed cardiac veins. This case report describes the angioplasty of a focal cardiac vein stenosis allowing for successful implantation of a left ventricular pacing lead. The safety of this procedure is unknown, though the risks may be acceptable in certain patients.
Irrigated Tip Catheter Ablation in Right Posteroseptal Accessory Pathways Resistant to Conventional Ablation
Authors: GARCÍA‐GARCÍA JAVIER , ALMENDRAL JESÚS , ARENAL ÁNGEL , SERRANO JOSÉ A. , RODRÍGUEZ JUAN CARLOS , MEDINA OLGA , VILLACASTÍN JULIÁN , TORRECILLA ESTEBAN , NIETO VICENTE
Published: July 2003

GARCÍA‐GARCÍA, J., et al.: Irrigated Tip Catheter Ablation in Right Posteroseptal Accessory Pathways Resistant to Conventional Ablation. Although RF ablation is an effective treatment of arrhythmias due to atrioventricular accessory pathways, there are cases refractory to conventional catheter ablation. Irrigated tip catheter ablation causes larger and especially deeper lesions than conventional ablation. This article discusses using irrigated tip catheter ablation in cases of right posteroseptal accessory pathways resistant to conventional ablation. Four consecutive patients with no structural heart disease and symptomatic arrhythmias related to right posteroseptal accessory pathways underwent irrigated tip catheter ablation. Conventional RF ablation had been unsuccessful in at least two procedures at more than one center (in three patients at the authors' center). The irrigated tip catheter (Chilli, Cardiac Pathways Corporation) uses a cooling system that is a closed circuit with a saline solution circulating at 0.6 mL/s. Temperature, power, and impedance were monitored during the RF applications. The procedure was successful in all four cases with no complications. In three of them, only one or two applications were necessary. Patients showed no recurrent arrhythmia during several months of follow‐up. The results of the present study suggest that RF ablation using an irrigated tip catheter can be useful (and seems to be safe) for the treatment of some right posteroseptal accessory pathways resistant to conventional ablation.
Effect of Coexisting Cardiovascular Disease on the Long‐Term Efficacy and Safety of the Implantable Atrial Defibrillator
Authors: TSE HUNG‐FAT , LAU CHU‐PAK , RODRIGUEZ LUZ‐MARIA , TIMMERMANS CARL , DAOUD EMILE G. , AYERS GREGORY M. , WELLENS HEIN J.J.
Published: July 2003

TSE, H.‐F., et al.: Effect of Coexisting Cardiovascular Disease on the Long‐Term Efficacy and Safety of the Implantable Atrial Defibrillator. The long‐term efficacy and safety of implantable atrial defibrillator (IAD) therapy in patients with AF and cardiovascular disease is unclear. The aim of this study was to evaluate the efficacy and safety of IAD therapy in patients with and without coexisting cardiovascular disease. In 115 patients implanted with an IAD, 85 patients had cardiovascular disease: 41 (48%) patients had 1 cardiovascular abnormality, 29 (35%) patients had 2, 13 (15%) patients had 3, and 2 (2%) patients had 4 different cardiovascular abnormalities. The device was programmed into a rhythm monitoring mode for the first 3‐month postimplant period. All defibrillation therapy was performed under physician supervision to monitor safety and efficacy. After this initial monitoring period, patients were allowed to activate their device away from the hospital or clinic. A total of 357 spontaneous AF episodes occurred in 83 (72%) patients during observed operation and the mean shock efficacy was 93.5 ± 20.3% (lower 95% confidence interval [CI] 89.8%). As of the last follow‐up, 58 (55%) patients had transition to receive nonphysician observed therapy. Forty‐two (72%) patients had experienced 332 episodes of AF for which they had received device therapy away from the hospital/clinic (mean shock efficacy 90.5 ± 39.7%). The presence of hypertension, valvular heart disease, and ischemic heart disease did not affect the shock efficacy of the IAD during physician observed and nonobserved therapy (P > 0.05). However, the presence of congestive heart failure was associated with a lower clinical efficacy during observed and nonobserved therapy (P < 0.05). Overall, 5,262 shocks have been delivered with the IAD without any episode of proarrhythmia. The observed proarrhythmic risk was 0%, with an estimated maximum proarrhythmic risk of 0.06% per shock (95% upper CI). A stand‐alone IAD appears to be safe in the presence of cardiovascular disease. The lower clinical efficacy for AF associated with congestive heart failure might be related to a higher rate of early reinitiation of AF after defibrillation.