bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Method of Mapping Atrial Premature Depolarizations Triggering Atrial Fibrillation
Authors: SCHWEIKERT ROBERT A. , LUGONES ALEJANDRO PEREZ , KANAGARATNAM LOGAN , TOMASSONI GERY , BEHEIRY SALWA , BASH DIANA , PISANO ENNIO , SALIBA WALID , TCHOU PATRICK J. , NATALE ANDREA
Published: July 2003

SCHWEIKERT, R.A., et al.: A Simple Method of Mapping Atrial Premature Depolarizations Triggering Atrial Fibrillation. Atrial premature depolarizations (APDs) originating from focal sites, particularly the pulmonary veins (PV), may become triggers of atrial fibrillation (AF). Accurate mapping of APDs with conventional methods may be time consuming and expose the patient to unnecessary instrumentation of the left atrium. We hypothesized that the atrial activation sequence recorded using a simple system that includes an esophageal catheter and a custom‐made 16‐electrode catheter with two sets of floating electrodes eight in the coronary sinus and eight in the high right atrium) could be sufficient to localize the APDs. The study included 29 patients with frequent APDs and AF refractory to antiarrhythmic medications. The APD site of origin was confirmed with single‐point sequential mapping techniques using the CARTO system ten patients) or by placement of multielectrode catheters in the right and left PV (19 patients). Of the 29 patients, 20 patients had a single APD focus; 8 patients had two different APD morphologies; and 1 patient had three APD foci. Mapping for ablation of the APD foci showed earliest activation in the left superior PV in 12 patients, right superior PV in 15 patients, right middle PV in 4 patients, right inferior PV in 1 patient, the lingular branch of the left superior PV in 2 patients, left inferior PV in 2 patients, and right atrium along the crista terminalis in 3 patients. The activation sequence and relative timing of the recordings obtained with our catheter configuration was highly predictive of right and left atrial origin and, more importantly, of right and left PV foci.
Mechanism of Spontaneous Transition from Typical Atrial Flutter to Atrial Fibrillation: Role of Ectopic Atrial Fibrillation Foci
Authors: HSIEH MING‐HSIUNG , TAI CHING‐TAI , TSAI CHIN‐FENG , YU WEN‐CHUNG , LIN WEI‐SHIANG , HUANG JIN‐LONG , DING YU‐AN , CHANG MAU‐SONG , CHEN SHIH‐ANN
Published: July 2003

HSIEH, M.‐H., et al.: Mechanism of Spontaneous Transition from Typical Atrial Flutter to Atrial Fibrillation: Role of Ectopic Atrial Fibrillation Foci. Paroxysmal AF has been known to be initiated by ectopic beats, especially in the pulmonary veins (PVs), and radiofrequency catheter ablation could cure it. We considered that the spontaneous transition from typical atrial flutter to AF also could be initiated by ectopic beats. Twenty patients (18 men, mean age 66 ± 14 years) with episodes of spontaneous transition from typical atrial flutter to AF were included in this study. They underwent detailed mapping of both atria. All the patients had spontaneous AF initiated by ectopic beats, and all of them had typical atrial flutter and spontaneous transition from typical atrial flutter (12 patients with counterclockwise atrial flutter and 8 patients with clockwise atrial flutter) to AF. The transition was initiated by ectopic beats from the PVs (17 foci, 85%), crista terminalis (2 foci, 10%), and superior vena cava (1 focus, 5%). After successful ablation of AF foci, typical atrial flutter was induced again, but no spontaneous transition was found after at least 10 minutes of observation. We concluded that paroxysmal AF and spontaneous transition from typical atrial flutter to AF were initiated by ectopic beats, and successful catheter ablation of the ectopic foci can eliminate paroxysmal AF and spontaneous transition from typical atrial flutter to AF.
Prospective Randomized Comparison of 50%/50% Versus 65%/65% Tilt Biphasic Waveform on Defibrillation in Humans
Authors: SWEENEY MICHAEL O. , NATALE ANDREA , VOLOSIN KENT J. , SWERDLOW CHARLES D. , BAKER JAMES H. , DEGROOT PAUL
Published: July 2003

SWEENEY, M.O., et al.: Prospective Randomized Comparison of 50%/50% Versus 65%/65% Tilt Biphasic Waveform on Defibrillation in Humans. It is unknown if there is a single optimal biphasic waveform for defibrillation. Biphasic waveform tilt may be an important determinant of defibrillation efficacy. The purpose of this study was to compare acute defibrillation success with a three‐electrode configuration in humans using 50%/50% versus 65%/65% tilt truncated exponential, biphasic waveforms delivered through a 110‐μF capacitor. Acute DFTs for biphasic waveforms with 50%/50% versus 65%/65% tilt were measured in random order in 60 patients using a binary search method. The electrode configuration consisted of a RV coil as the cathode, and a SVC coil plus a pectoral active can emulator (CAN) as the anode. The waveforms were derived from an external voltage source with 110‐μF capacitance, and the leading edge voltage of phase 2 was equal to the trailing edge voltage of phase 1. Stored energy DFT (9.2 ± 5.7 [50%/50%] vs 10.8 ± 6.4 [65%/65%] J, P = 0.007), current DFT (10.9 ± 4.0 [50%/50%] vs 12.0 ± 4.4 [65%/65%] A, P = 0.002) and voltage DFT (391 ± 118 [50%/50%] vs 424 ± 128 [65%/65%] V, P = 0.004) were significantly lower for the 50%/50% tilt waveform versus the 65%/65% tilt waveform using this three‐electrode configuration and a 110‐μF capacitor. For an RV (‐)/SVC plus CAN (+) electrode configuration and a 110‐μF capacitor, a 50%/50% tilt biphasic waveform results in a 15% reduction in energy DFT, 9% reduction in current DFT, and 8% reduction in voltage DFT versus a 65%/65% tilt biphasic waveform.
Catheter Ablation in the Elderly in the United States: Use in the Medicare Population from 1991 to 1998
Authors: SMITH PETER N. , VIDAILLET HUMBERTO , SHARMA PARAM P. , HAYES JOHN J. , SCHMELZER JOHN R.
Published: July 2003

SMITH, P.N., et al.: Catheter Ablation in the Elderly in the United States: Use in the Medicare Population from 1991 to 1998. The safety and efficacy of catheter ablation for the treatment of drug refractory cardiac arrhythmias is well established in young patients. Little is known about its effectiveness or use in the elderly. We determined trends in the use of catheter ablation in the United States Medicare population. Data were obtained from the approximately 30 million patients covered each year by Medicare's fee‐for‐service program of the Health Care Financing Administration of the Department of Health and Human Services. From 1991 to 1998, Medicare's fee‐for‐service beneficiaries covered 80%–93% of all adults > 65 years old in the United States. All catheter‐based ablative procedures performed in this population were identified through the use of the Current Procedural Terminology codes 93650, 93651, and 93652. Use rate per 1 million beneficiaries grew from 33 in 1991 to 603 in 1998. While during this 7‐year period the Medicare fee‐for‐service population decreased by 8%, ablations increased 16‐fold (1,608%). The use of catheter ablation in the older American grew exponentially during the 1990s. Further research is needed to determine the optimal use of this potentially curative technique in the elderly.
Feasibility and Initial Results of an Internet‐Based Pacemaker and ICD Pulse Generator and Lead Registry
Authors: HAUSER ROBERT , HAYES DAVID , PARSONNET VICTOR , FURMAN SEYMOUR , EPSTEIN ANDREW , HAYES JOHN , SAKSENA SANJEEV , IRWIN MARLEEN , ALMQUIST ADRIAN , CANNOM DAVID , GROSS JAY , KALLINEN LINDA
Published: July 2003

HAUSER, R., et al.: Feasibility and Initial Results of an Internet‐Based Pacemaker and ICD Pulse Generator and Lead Registry. The medical community has no independent source of timely information regarding the performance of pacemaker and ICD pulse generators and leads. Accordingly, the authors established an Internet‐based registry of pacemaker and ICD pulse generator and lead failures (www.pacerandicregistry.com). During the first year, they found three previously unreported device problems that were promptly communicated to the participants. Of the failures reported, 11% of ICD and 10% of pacemaker pulse generator failures were heralded by signs other than the expected elective replacement indicator (ERI). Average ICD battery longevity was 4.0 ± 0.7 years, and average dual chamber pacemaker battery longevity was 6.8 ± 2.6 years. Disrupted insulation accounted for 54% of pacemaker and 29% of ICD lead failures. Compared to pacemaker pulse generator and lead failure, ICD device failures were more likely to cause severe clinical consequences. In conclusion, an Internet‐based registry is feasible and capable of providing timely data regarding the signs, causes, and clinical consequences of pacemaker and ICD failures.
Transvenous Low Energy Internal Cardioversion for Atrial Fibrillation: A Review of Clinical Applications and Future Developments
Authors: BORIANI GIUSEPPE , BIFFI MAURO , CAMANINI CLAUDIA , LUCERI RICHARD M. , BRANZI ANGELO
Published: July 2003

BORIANI, G., et al.: Transvenous Low Energy Internal Cardioversion for Atrial Fibrillation: A Review of Clinical Applications and Future Developments. Low energy internal atrial cardioversion can be performed by delivering biphasic shocks between transvenous catheters positioned within the cardiac chambers or great vessels. Delivery of shocks results in effective cardioversion at energies < 6–10 J and the procedure can be effective even when external cardioversion has failed. Shock induced discomfort varies from patient to patient, but the procedure can be usually performed without general anesthesia and eventually under mild sedation. Nevertheless, tolerability has to be improved by obtaining a substantial reduction in defibrillating thresholds. With regard to safety, delivery of shocks for defibrillating the atria implies a potential risk of inducing ventricular fibrillation; to minimize this risk, shock delivery must be synchronous to the QRS and should be avoided during rapid RR cycles (< 300 ms). Presently, transvenous low energy cardioversion is an investigational procedure, but a widening of indications is expected in the near future. The cost of the procedure, which remains invasive and requires a brief hospital stay, must be balanced with the benefit of restoring sinus rhythm and the possibility of maintaining sinus rhythm for the medium‐ to long‐term. Experimental and clinical investigations of low energy internal cardioversion have resulted in the development of devices for atrial defibrillation whose clinical role and cost‐benefit ratio is currently under evaluation.
Long‐Term Follow‐Up of Left Ventricular Pacing via a Posterior Cardiac Vein After Mechanical Tricuspid Valve Replacement
Authors: WINTER JOACHIM , GRAMSCH‐ZABEL HILDEGARD , FÜRST GÜNTHER , KOCH JENS‐ALBRECHT , ZIMMERMANN NORBERT , GAMS EMMERAN
Published: July 2003

WINTER, J., et al.: Long‐Term Follow‐Up of Left Ventricular Pacing via a Posterior Cardiac Vein After Mechanical Tricuspid Valve Replacement. Permanent cardiac pacing was recommended in a 66‐year‐old woman with mechanical prosthetic mitral and tricuspid valves. To avoid a thoracotomy, a conventional endocardial lead was inserted with a steerable stylet (Locator) into the posterior cardiac vein via the right cephalic vein. Four weeks later, lead dislodgement required reoperation. The lead position remained stable up to 29 months.
Intermittent Output Failure of a VVI Device Due to the Disintegration of the Generator
Authors: BÖHM ADAM , KAYSER SÁNDOR , PINTÉR ARNOLD , PRÉDA ISTVÁN
Published: July 2003

BÖHM, A., et al.: Intermittent Output Failure of a VVI Device Due to the Disintegration of the Generator. The metal case and the header of a Biovallees Coralite 247 pacemaker fell apart in a patient resulting in syncope due to myopotential inhibition. Upon recalling our patients with that type of device, we found a similar technological failure in 11 of 16 of them. This finding warrants a consideration for recalling that Biovallees device.
Mapping of Atrial Activation Patterns After Inducing Contiguous Radiofrequency Lesions: An Experimental Study
Authors: CHORRO FRANCISCO J. , MAINAR LUIS , SANCHIS JUAN , CÁNOVES JOAQUÍN , LLAVADOR ESTEBAN , SUCH LUIS M. , CERDÁ MIGUEL , LÓPEZ‐MERINO VICENTE , SUCH LUIS
Published: July 2003

CHORRO, F.J., et al.: Mapping of Atrial Activation Patterns After Inducing Contiguous Radiofrequency Lesions: An Experimental Study. High resolution mapping techniques are used to analyze the changes in atrial activation patterns produced by contiguous RF induced lesions. In 12 Langendorff‐perfused rabbit hearts, left atrial activation maps were obtained before and after RF induction of epicardial lesions following a triple‐phase sequential protocol: (phase 1) three separate lesions positioned vertically in the central zone of the left atrial wall; (phase 2) the addition of two lesions located between the central lesion and the upper and lower lesions; and (phase 3) the placement of four additional lesions between those induced in the previous phases. In six additional experiments a pathological analysis of the individual RF lesions was performed. In phase 1 (lesion diameter = 2.8 ± 0.2 mm, gap between lesions = 3 ± 0.8 mm), the activation process bordered the lesions line in two (2.0‐ms cycles) and four experiments (1.0‐ms cycles). In phase 2, activation bordered the lesions line in eight (2.0‐ms cycles, P < 0.01 vs control) and nine experiments (1.0‐ms cycles, P < 0.001), and in phase 3 this occurred in all experiments except one (both cycles, P < 0.001 vs control). In the experiments with conduction block, the increment of the interval between activation times proximal and distal to the lesions showed a significant correlation to the length of the lesions (r = 0.68, P < 0.05, 100‐ms cycle). In two (17%) experiments, sustained regular tachycardias were induced with reentrant activation patterns around the lesions line. In conclusion, in this acute model, atrial RF lesions with intact tissue gaps of 3 mm between them interrupt conduction occasionally, and conduction block may be frequency dependent. Lesion overlap is required to achieve complete conduction block lines. Tachycardias with reentrant activation patterns around a lesions line may be induced.
Reversal of Tachycardia Induced Cardiomyopathy Following Ablation of Repetitive Monomorphic Right Ventricular Outflow Tract Tachycardia
Authors: GRIMM WOLFRAM , MENZ VOLKER , HOFFMANN JÜRGEN , MAISCH BERNHARD
Published: July 2003

GRIMM, W., et al.: Reversal of Tachycardia Induced Cardiomyopathy Following Ablation of Repetitive Monomorphic Right Ventricular Outflow Tract Tachycardia. Radiofrequency catheter ablation was performed in four adults with myocardial dysfunction related to repetitive monomorphic ventricular tachycardia (RMVT) originating in the right ventricular outflow tract. Serial echocardiographic assessment of left ventricular function before and after radiofrequency catheter ablation of RMVT showed complete reversal of left ventricular dysfunction without arrhythmia recurrence during 31 ± 28 months follow‐up.
Extension of Generator Longevity by Use of High Impedance Ventricular Leads
Authors: SCHERER MIRELA , EZZIDDIN KHALED , KLESIUS ARMIN , SKUPIN MANFRED , HELMS STEPHAN , MORITZ ANTON , OLBRICH HANS‐GEORG
Published: July 2003

SCHERER, M., et al.: Extension of Generator Longevity by Use of High Impedance Ventricular Leads. The resistance of a pacing lead negatively correlates to current consumption. A prospective, randomized trial was conducted to evaluate the effect of a high impedance ventricular lead (CapSure Z) on generator longevity compared to a conventional lead (CapSure SP) eighty‐nine patients were included in the study (51 male, 37 female, age 70.0 ± 10.3 years). Forty‐six patients received a CapSure SP lead (5024 bipolar), and 43 patients received a CapSure Z lead (5034 bipolar) in a randomized fashion. Follow‐up data collected at 5 days, 3, 6, and 12 months postimplant included: lead impedance, pacing and sensing thresholds, impulse energy, and estimated time to replacement. All parameters were collected via pacemaker telemetry; the time to replacement was calculated automatically by a programmed algorithm of the pacemaker. There was no difference in the performance of the atrial lead when a dual chamber device was indicated. The CapSure Z leads displayed statistically significant higher impedance values than the CapSure SP lead in all follow‐up periods. There was no significant difference in lead related complications. No significant differences were observed between pacing and sensing thresholds in both groups. The CapSure Z leads provided a significant reduction in current drain, resulting in a reduction of mean energy consumption at the 12‐month follow‐up from 10.4 ± 5.0 μJ in the CapSure SP group to 6.6 ± 1.4 μJ in the CapSure Z group (median from 9.9 μJ to 6.9 μJ, respectively), providing an estimated increase in mean longevity of more than 1 year from 81.1 ± 23.5 months in the CapSure SP group to 94.5 ± 13.4 months in the CapSure Z group (median: 76.5 months to 95.0 months, respectively). The use of a high resistance lead for ventricular pacing appears to result in a clinically relevant extension of generator longevity.
Adjustment of the Evoked Response Sensitivity After Hospital Discharge in Pacemaker Patients with Automatic Ventricular Threshold Tracking Activated
Authors: SCHUCHERT ANDREAS , VENTURA RODOLFO , MEINERTZ THOMAS
Published: July 2003

SCHUCHERT, A., et al.: Adjustment of the Evoked Response Sensitivity After Hospital Discharge in Pacemaker Patients with Automatic Ventricular Threshold Tracking Activated. Automatic threshold tracking in cardiac pacemakers allows ventricular capture verification and self‐adaptive pacing output regulation. The Autocapture algorithm detects the evoked response (ER) signal immediately after the pacing pulse to verify the efficacy of ventricular pacing. Before hospital delivery, the ER sensitivity must be programmed individually so that the pacemaker detects the ER signal adequately without sensing lead polarization. The aims of the study were to assess the frequency of patients in whom Autocapture could be activated and whether the ER sensitivity had to be adjusted after hospital discharge. The study included 44 patients who received the VVIR pacemaker Regency SR+ (St. Jude Medical) connected to the model 1450 T pacing lead. ER signal, lead polarization, and ER sensitivity were evaluated before hospital discharge and 1, 3, and 6 months after implantation. The system recommended activating Autocapture in 42 of 44 patients. The mean ER signal was 8.4 ± 1.2 mV at discharge, 9.0 ± 3.9 mV at month 1, 8.9 ± 4.9 mV at month 3, and 9.3 ± 4.5 mV at month 6. Polarization was 1.0 ± 0.1 mV at discharge, 1.1 ± 0.5 mV at month 1, 1.1 ± 0.2 mV at month 3, and 1.1 ± 0.5 mV at month 6. Mean ER sensitivity was 3.7 ± 1.8 mV at discharge, 4.0 ± 1.8 mV after 1, 4.1 ± 2.2 mV after 3, and 4.1 ± 1.8 mV after 6 months. ER sensitivity could remain unadjusted in 14 patients. Programming to a less sensitive ER setting from 2.9 ± 1.2 mV to 4.3 ± 1.5 mV was possible in 21 patients. Programming to a more sensitive ER setting from 4.1 ± 1.1 mV to 2.5 ± 0.9 mV was required in nine patients because of the decrease of the ER signal. The automatic threshold tracking algorithm Autocapture could be activated in 95% of patients. Programming to more sensitive ER settings was recommended in 21% of the patients after hospital discharge. Therefore, ER signal and polarization must be checked at each follow‐up, as a decrease in ER signal amplitude can make reprogramming of the ER sensitivity necessary. There is no risk for the patient if the ER is not sensed, as high voltage backup stimulation is present.
Inactivation of a Ventricular Tachycardia Preventive Algorithm During Automatic Mode Switching for Atrial Tachyarrhythmia
Authors: EGUÍA LUIS E. , PINSKI SERGIO L.
Published: July 2003

EGUÍA, L.E., et al.: Inactivation of a Ventricular Tachycardia Preventive Algorithm During Automatic Mode Switching for Atrial Tachyarrhythmia. A patient with a dual chamber implantable defibrillator and pause dependent VT in whom a rate smoothing algorithm failed to operate during automatic mode switching due to device idiosyncrasy is reported. Preventive measures are discussed.
Ancillary Tools in Pacemaker and Defibrillator Lead Extraction Using a Novel Lead Removal System
Authors: MANOLIS ANTONIS S. , MAOUNIS THEMOS N. , VASSILIKOS VASSILIS , CHILADAKIS JOHN , MELITA‐MANOLIS HELEN , COKKINOS DENNIS V.
Published: July 2003

MANOLIS, A.S., et al.: Ancillary Tools in Pacemaker and Defibrillator Lead Extraction Using a Novel Lead Removal System. A previous report described our preliminary experience with a highly successful pacing lead removal system (VascoExtor). Extending this experience, we found it necessary to use additional tools to enhance the success of percutaneous lead extraction with this system. In the present series, we used the standard locking stylets (S and K), and recently, one newer type of stylet (Magic) over the last 3 years in 34 patients to extract 48 pacemaker leads in 31 patients and 3 defibrillator (ICD) leads in 3 patients. Lead extraction was carried out in 23 men and 11 women (aged 64 ± 17 years) because of pacemaker infection (n = 21), pacemaker (n = 8) or ICD (n = 3) lead malfunction, or prior to ICD implant (n = 2). Leads were in place for 3.5 ± 3.7 years. Infections, involving pocket and lead(s), were due to S. epidermidis (n = 13), S. aureus (n = 6), S. aureus plus E. coli (n = 1), or fungi (n = 1). Of the 48 pacing leads, 31 were ventricular, 15 atrial, and 2 were VDD leads. The ICD leads were two double‐coil leads (CPI) and one single‐coil lead (Telectronics). Using the S (n = 12), K (n = 8), or Magic (n = 3) stylets, all pacing leads in 23 patients and the ICD leads in 2 patients were successfully removed from a subclavian approach using the locking stylets. However, in nine (26.5%) patients ancillary tools were required. In four patients, lead fragments were captured with use of a noose catheter, a pigtail catheter, and a bioptome from a right femoral approach. In two patients, locking could not be effected and a noose catheter from the right femoral vein was used, aided by a pigtail and an Amplatz catheter and a bioptome to remove three leads. In a patient with an ICD lead, a combined subclavian (stylet S) and right femoral approach (noose catheter) was required. In a patient with a dysfunctional ventricular lead 12 years old, a motor drive unit was used to facilitate the exchange of locking stylets, but extraction failed. In another patient, a fragment of a dysfunctional ventricular lead remained intravascularly despite resorting to a femoral approach. Finally, lead removal was completely (32/34, 94%) or partially (1/34, 3%) successful in 33 (97%) of 34 patients for 50 (98%) of 51 leads without complications. In conclusion, to enhance the success of pacing or ICD lead extraction with use of the VascoExtor locking stylets, an array of ancillary tools were required in more than one fourth of patients.
Paradoxical Undersensing at a High Sensitivity in Dual Chamber Pacemakers
Authors: WILLEMS RIK , HOLEMANS PATRICIA , ECTOR HUGO , VAN DE WERF FRANS , HEIDBÜCHEL HEIN
Published: July 2003

WILLEMS, R., et al.: Paradoxical Undersensing at a High Sensitivity in Dual Chamber Pacemakers. In view of the evolving indications for device therapy in atrial arrhythmia the accurate detection of high rate atrial events is a necessity. In a sheep model of atrial fibrillation (AF) we observed a contradictory behavior of the Thera DR pacemaker. The pacemakers were programmed to deliver burst pacing on detection of sinus rhythm (SR). Paradoxically, progressively more inappropriate bursts were delivered during AF, at a higher sensitivity. This implied that the pacemaker interpreted AF as SR. We assessed the atrial detection of the Thera DR, Diamond, Saphir, and Marathon pacemakers during AF, in a sheep model and in vitro using a waveform generator. By counting the annotated atrial‐sensed events reported by the pacemaker we charted the behavior of the pacemakers at different sensitivities. At a higher sensitivity both the Thera DR and the Diamond paradoxically reported fewer atrial events during AF. This behavior led to inappropriate mode switching and incorrect diagnostic data collection. It could be reproduced in vitro. The Marathon did not show this paradoxical undersensing in vivo or in vitro. This paradoxical undersensing at a high sensitivity is dependent on the amplitude of the input signal and could not be explained by an overlap of programmable timing parameters. It is caused by ringing of the atrial sensing amplifier. At high atrial rates and a high sensitivity the ringing of the repetitive atrial signal input results in blanking of the atrial amplifier. This observation may be relevant in the device management of patients with paroxysmal AF.
The Effect of the Atrial Pacing Site on the Total Atrial Activation Time
Authors: ROITHINGER FRANZ X. , ABOU‐HARB MARIA , PACHINGER OTMAR , HINTRINGER FLORIAN
Published: July 2003

ROITHINGER, F.X., et al.: The Effect of the Atrial Pacing Site on the Total Atrial Activation Time. The effect of dual site pacing for prevention of atrial fibrillation may be due to synchronization of right and left atrial activation. Little is known, however, about the effect of pacing from single right atrial sites on differences in interatrial conduction. Twenty‐eight patients without structural heart disease were studied following radiofrequency catheter ablation of supraventricular arrhythmias. Pacing was performed using standard multipolar catheters from the presumed insertion site of Bachmann's bundle, the coronary sinus ostium, the high lateral right atrium, and the right atrial appendage (n = 8 patients). Bipolar recording was performed from the distal coronary sinus, the high and low lateral right atrium, and the posterolateral left atrium (n = 13 patients). The longest conduction time from each pacing to each recording site was considered the total atrial activation time for the respective pacing site. During high right atrial pacing, the total atrial activation time was determined by the conduction to the distal coronary sinus (118 ± 18 ms), during coronary sinus ostium pacing by the conduction to the high right atrium (94 ± 18 ms), and during Bachmann's bundle pacing by the conduction to the distal coronary sinus (74 ± 18 ms). The total atrial activation time was signifiantly shorter during pacing from Bachmann's bundle, as compared to pacing from other right atrial sites. Thus, in normal atria, pacing from the insertion of Bachmann's bundle causes a shorter total atrial activation time and less interatrial conduction delay, as compared to pacing from other right atrial sites. These findings may have implications for alternative pacing sites for prevention of atrial fibrillation.
Effect of Ischemic Stroke on the Dynamic Beat‐to‐Beat QT‐RR Relationship
Authors: ARAD MARINA , ABBOUD SHIMON , RADAI MICHAL M. , ADUNSKY ABRAHAM
Published: July 2003

ARAD, M., et al.: Effect of Ischemic Stroke on the Dynamic Beat‐to‐Beat QT‐RR Relationship. The ECGs of 26 patients following ischemic stroke and 18 control patients with various orthopedic problems, all without primary heart disease, were examined to characterize the dynamic behavior of uncorrected QT interval in relation to changing RR interval during physiotherapy effort. ECG waveforms were analyzed to extract beat‐to‐beat QT and RR intervals. Based on performing multiple cross‐correlations, the relationship between the RR and QT intervals was calculated using the following general formula QTi = c RRbi‐1. Linear regression was performed on the logarithms of QT and RR measurements to estimate the constant (a = log c) and the slope (b) values, reflecting the dynamic change of QT during physiotherapy effort. Having these two values, the dynamic QT extrapolated to a heart period of 1 second (QTcd) was calculated. It was found that the mean slope (b) of the linear regression line in the ischemic stroke group was significantly lower than in the control group (0.26 ± 0.08 vs 0.33 ± 0.08, P < 0.02), and the constant (a) was significantly higher (1.83 ± 0.21 for the ischemic stroke vs 1.61 ± 0.23 for the controls, P < 0.002). No significant difference was found in QTcd values between the two groups (386 ± 27 ms for the ischemic stroke vs 392 ± 25 ms for the controls, P > 0.05). In conclusion, hemispheric brain infarction seems to result in alteration in the autonomic activity during exercise manifesting itself as distorted dynamic behavior of the QT interval.
Antitachycardia Pacing for Rapid VT During ICD Charging: A Method to Prevent ICD Shocks
Authors: WEBER MAX , BLOCK M. , BÄNSCH D. , CASTRUCCI M. , GRADAUS R. , SCHRIEVER C. , BREITHARDT GÜNTHER , BÖCKER D.
Published: July 2003

WEBER, M., et al.: Antitachycardia Pacing for Rapid VT During ICD Charging: A Method to Prevent ICD Shocks. In patients with ICDs, rapid VTs are usually treated with shocks. It is unknown, if antitachycardia pacing (ATP) delivered once for rapid VT during capacitor charging can avoid painful shocks without increasing the risk of syncope. In patients in whom rapid monomorphic VT (cycle length 300–220 ms) could be reproducibly induced during predischarge ICD testing, the success of cardioversion (defibrillation threshold plus 10 J) and a single ATP attempt (burst with 8 or 16 stimuli) was compared using a randomized crossover study design. Consciousness of the patients was checked by the signal from a button constantly pushed by the patient. In 20 patients (ejection fraction 0.50 ± 0.19) rapid VTs (253 ± 26 ms) were reproducibly induced. A single burst successfully terminated 11 (55%) of 20 rapid VTs, 6 episodes could not be terminated with a single burst pacing and 3 VTs accelerated. Rapid VTs not terminated by ATP were significantly faster than those that could be terminated (246 vs 258 ms, P = 0.026). Cardioversion (19 ± 3 J) terminated the VTs in all cases. No patient suffered syncope during rapid VTs. A single ATP may terminate rapid VT with cycle lengths < 300 ms in 55% of patients without increasing the risk of syncope. Therefore, in rapid VTs one attempt of ATP may be suitable as an additional therapy option during ICD capacitor charging to avoid painful shocks without compromise of safety. Thus, future ICDs should implement the option of ATP during charging of capacitors.
QT Interval Dispersion in Ventricular Beats: A Noninvasive Marker of Susceptibility to Sustained Ventricular Arrhythmias
Authors: KULAKOWSKI PIOTR , KARCZMAREWICZ STEFAN , CZEPIEL ALEKSANDRA , MAKOWSKA EWA , SOSZYŃSKA MALGORZATA , CEREMUŻYŃSKI LESZEK
Published: July 2003

KULAKOWSKI, P., et al.: QT Interval Dispersion in Ventricular Beats: A Noninvasive Marker of Susceptibility to Sustained Ventricular Arrhythmias. Increased QT dispersion (QTd) calculated from sinus beats has been shown to identify patients prone to sustained VT. However, predictive accuracy of this parameter is limited. Electrophysiological properties of the myocardium may be altered by a premature ventricular beats, which is a well‐established trigger for sustained VT. Therefore, the author hypothesised that QTd in spontaneous or paced ventricular beats may improve identification of patients with inducible sustained VT. In 28 consecutive patients (men, mean age 61 ± 13 years) who underwent programmed ventricular stimulation, the values of QTd calculated in sinus and ventricular beats were compared between inducible and noninducible patients. The mean QTd values obtained using three different methods differed significantly, QTd in paced ventricular beats being the highest, QTd in spontaneous ventricular beats was intermediate, and QTd in sinus beats was the lowest (83.9 ± 30 vs 63.0 ± 29 ms vs 53.9 ± 27 ms, P < 0.0001 and P < 0.004, respectively). In 13 (46%) patients sustained VT was induced. QTd values were significantly higher in inducible than noninducible patients (QTd sinus beats: 67.5 ± 31 vs 42.1 ± 11 ms, P = 0.02; QTd spontaneous ventricular beats: 79.3 ± 35 vs 46.7 ± 13 ms, P = 0.008, and QTd‐paced ventricular beats: 104.8 ± 32 vs 65.9 ± 9 ms, P = 0.0009). The receiver operator characteristic curves showed that at a sensitivity level of 100%, the highest specificity for identification of inducible patients had QTd measured in paced ventricular beats (87%) followed by QTd in spontaneous ventricular beats (45%), and QTd in sinus beats (40%). In conclusion, (1) QTd in ventricular beats is greater than in sinus beats, and (2) QTd calculated from paced ventricular beats identifies patients with inducible sustained VT better than QTd measured during sinus rhythm.
AV Block and Changes in Pacing Mode During Long‐Term Follow‐Up of 399 Consecutive Patients with Sick Sinus Syndrome Treated with an AAI/AAIR Pacemaker
Authors: KRISTENSEN LENE , NIELSEN JENS COSEDIS , PEDERSEN ANDERS KIRSTEIN , MORTENSEN PETER THOMAS , ANDERSEN HENNING RUD
Published: July 2003

KRISTENSEN, L., et al.: AV Block and Changes in Pacing Mode During Long‐Term Follow‐Up of 399 Consecutive Patients with Sick Sinus Syndrome Treated with an AAI/AAIR Pacemaker. This retrospective study included a large cohort of consecutive patients primarily implanted at Skejby University Hospital with an AAI/AAIR pacemaker because of sick sinus syndrome (SSS) from July 1981 to July 1999. The primary aim of the study was to analyze the risk of developing AV block during long‐term follow‐up. A secondary aim was to study the incidence and reasons for changes in pacing mode caused by other than AV block. A total of 399 patients (231 women, mean age 71 ± 13.5 years) were identified. Mean follow‐up was 4.6 ± 3.4 years and occurred at death, reoperation with mode change, pacemaker explant, or end of study. During follow‐up, 44 patients had a ventricular lead implanted with a mean delay of 2.8 ± 3.1 years (range 1 day‐10.4 years) after the primary implantation. A total of 30 patients received a ventricular lead because of AV block or AF with bradycardia (annual incidence 1.7%). Another 14 patients received a ventricular lead without having documented AV block or AF with pauses (annual incidence 0.8%). The present observational study documents that in patients with SSS treated with AAI/AAIR pacing, AV block requiring implantation of a ventricular lead occurs at a rate of 1.7% per year. It is considered that AAI/AAIR pacing is safe and reliable as treatment for patients with SSS and normal AV conduction.
Lead Insertion by Supraclavicular Approach of the Subclavian Vein Puncture
Authors: ANTONELLI DANTE , FREEDBERG NAHUM A. , ROSENFELD TIBERIO
Published: July 2003

ANTONELLI, D., et al.: Lead Insertion by Supraclavicular Approach of the Subclavian Vein Puncture. Total occlusion of the left subclavian vein was diagnosed in a 76‐year‐old patient, 6 years after implantation of an ICD with VVI pacing backup. Replacement of the ICD included upgrading of the ICD system because of the presence of pacemaker syndrome when the patient was VVI paced. Insertion of an atrial lead through the ipsilateral vein system was made possible by using the supraclavicular approach of the subclavian, enabling puncturing of the left subclavian vein medially to the obstruction.
Prospective Randomized Comparison of the Safety and Effectiveness of Placement of Endocardial Pacemaker and Defibrillator Leads Using the Extrathoracic Subclavian Vein Guided by Contrast Venography Versus the Cephalic Approach
Authors: CALKINS HUGH , RAMZA BRIAN M. , BRINKER JEFFREY , ATIGA WALTER , DONAHUE KEVIN , NSAH EMMANUEL , TAYLOR ERIC , HALPERIN HENRY , LAWRENCE JOHN H. , TOMASELLI GORDON , BERGER RONALD D.
Published: July 2003

CALKINS, H., et al.: Prospective Randomized Comparison of the Safety and Effectiveness of Placement of Endocardial Pacemaker and Defibrillator Leads Using the Extrathoracic Subclavian Vein Guided by Contrast Venography Versus the Cephalic Approach. The purpose of this prospective randomized study was to compare the safety and efficacy of the cephalic approach versus a contrast‐guided extrathoracic approach for placement of endocardial leads. Despite an increased incidence of lead fracture, the intrathoracic subclavian approach remains the dominant approach for placement of pacemaker and implantable defibrillator leads. Although this complication can be prevented by lead placement in the cephalic vein or by lead placement in the extrathoracic subclavian or axillary vein, these approaches have not gained acceptance. A total of 200 patients were randomized to undergo placement of pacemaker or implantable defibrillator leads via the contrast‐guided extrathoracic subclavian vein approach or the cephalic approach. Lead placement was accomplished in 99 of the 100 patients randomized to the extrathoracic subclavian vein approach as compared to 64 of 100 patients using the cephalic approach. In addition to a higher initial success rate, the extrathoracic subclavian vein medial approach was determined to be preferable as evidenced by a shorter procedure time and less blood loss. There was no difference in the incidence of complications. In conclusion, these results demonstrate that lead placement in the extrathoracic subclavian vein guided by contrast venography is effective and safe. It was also associated with no increased risk of complications as compared with the cephalic approach. These findings suggest that the contrast‐guided approach to the extrathoracic portion of the subclavian vein should be considered as an alternative to the cephalic approach.
Interference with Cardiac Pacemakers by Magnetic Resonance Imaging: Are There Irreversible Changes at 0.5 Tesla?
Authors: VAHLHAUS CHRISTIAN , SOMMER TORSTEN , LEWALTER THORSTEN , SCHIMPF RAINER , SCHUMACHER BURGHARD , JUNG WERNER , LÜDERITZ BERNDT
Published: July 2003

VAHLHAUS, C., et al.: Interference with Cardiac Pacemakers by Magnetic Resonance Imaging: Are There Irreversible Changes at 0.5 Tesla? The safety and feasibility of magnetic resonance imaging (MRI) in patients with cardiac pacemakers is an issue of gaining significance. The effect of MRI on patients' pacemaker systems has only been analyzed retrospectively in some case reports. Therefore, this study prospectively investigated if MRI causes irreversible changes in patients' pacemaker systems. The effect of MRI at 0.5 Tesla on sensing and stimulation thresholds, lead impedance and battery voltage, current, and impedance was estimated during 34 MRI examinations in 32 patients with implanted pacemakers. After measurements at baseline and with documentation of intrinsic rhythm and modification of the pacing mode, patients underwent MRI. The rest of the function time of the pacemaker was calculated. Measurements were again performed after 99.5 ± 29.6 minutes (mean ± SD), immediately after MRI examination, and 3 months later. Lead impedance and sensing and stimulation thresholds did not change after MRI. Battery voltage decreased immediately after MRI and recovered 3 months later. Battery current and impedance tended to increase. The calculated rest of function time did not change immediately after MRI. MRI affected neither pacemaker programmed data, nor the ability to interrogate, program, or use telemetry. Surprisingly, in the gantry of the scanner, temporary deactivation of the reed switch occurred in 12 of 32 patients when positioned in the center of the magnetic field. Missing activation of the reed switch through the static magnetic field at 0.5 Tesla is not unusual. MRI at 0.5 Tesla does not cause irreversible changes in patients' pacemaker systems.
Twenty‐Seven‐Year Follow‐up of Arrhythmogenic Right Ventricular Dysplasia
Authors: OBATA HIROMI , MITSUOKA TAKAO , KIKUCHI YOUICHI , SAKURADA TAKU , KUSAJIMA KATSUYUKI , KAWAMURA YUICHIRO , KIKUCHI KENJIRO
Published: July 2003

OBATA, H., et al.: Twenty‐Seven‐Year Follow‐up of Arrhythmogenic Right Ventricular Dysplasia. This case report describes clinical features, especially of surface ECG changes, observed for 27 years in a patient with arrhythmogenic right ventricular dysplasia (ARVD). The course of this patient was characterized by progressive deterioration of right ventricular function and progression of delayed potentials (so‐called epsilon waves) following QRS complexes. However, the relation between ventricular arrhythmias and ECG changes or the degree of right ventricular abnormality was difficult to discern.
Dual AV Nodal Pathway Physiology After Injury with Radiofrequency Energy in a Patient Without a History of Reentrant Tachycardia
Authors: PATRAWALA ROB A. , SHARMA ARJUN D. , O'NEILL GEAROID
Published: July 2003

PATRAWALA, R.A., et al.: Dual AV Nodal Pathway Physiology After Injury with Radiofrequency Energy in a Patient Without a History of Reentrant Tachycardia. Radiofrequency (RF) atrioventricular (AV) nodal modification has been reported to occasionally produce a proarrhythmic effect. Dual AV nodal pathway physiology in patients without reentrant tachychardia has also been reported. This case describes AV nodal modification with RF energy in an anatomically intermediate area resulting in the appearance of discontinuous antegrade conduction curves and reentry in a patient in which these were previously not present. This suggests that AV nodal injury may be a mechanism for acquired AV nodal reentry.
ICD Malfunction Caused by Excessive Defibrillation Charge Time
Authors: DE MEESTER ANTOINE , GILLES PAUL‐HENRI
Published: July 2003

DE MEESTER, A., et al.: ICD Malfunction Caused by Excessive Defibrillation Charge Time. A 71‐year‐old man with a history of myocardial infarction and syncopal ventricular tachycardia received an ICD. Progressively, increased defibrillation charge times of the ICD were observed. During a fast ventricular tachycardia, the patient collapsed. The underlying malfunction could be documented by ICD telemetric interrogation. An excessive charge time was recorded causing subsequent delayed therapy. The ICD was considered potentially ineffective and required a generator exchange. This case report underlines the possible factors affecting the ICD charge times. Excessive charge time must be considered as a rare, or underestimated, cause of ICD malfunction, requiring generator replacement.
Clinical Significance of the Atrial Fibrillation Threshold in Patients with Paroxysmal Atrial Fibrillation
Authors: INOUE KEIJI , SHIRAYAMA TAKESHI , SHIRAISHI HIROKAZU , MATOBA YAYOI , IMAI HIROTO , INOUE DAISUKE , NAKAGAWA MASAO
Published: July 2003

INOUE, K., et al.: Clinical Significance of the Atrial Fibrillation Threshold in Patients with Paroxysmal Atrial Fibrillation. AF threshold and the other electrophysiological parameters were measured to quantify atrial vulnerability in patients with paroxysmal atrial fibrillation (PAF, n = 47), and those without AF (non‐PAF, n = 25). Stimulations were delivered at the right atrial appendage with a basic cycle length of 500 ms. The PAF group had a significantly larger percentage of maximum atrial fragmentation (%MAF, non‐PAF: mean ± SD = 149 ± 19%, PAF: 166 ± 26%, P = 0.009), fragmented atrial activity zone (FAZ, non‐PAF: median 0 ms, interquartile range 0–20 ms, PAF: 20 ms, 10–40 ms, P = 0.008). Atrial fibrillation threshold (AF threshold, non‐PAF: median 11 mA, interquartile range 6–21 mA, PAF: 5 mA, 3–6 mA, P < 0.001) was smaller in the PAF group than in the non‐PAF group. Sensitivity, specificity, and positive predictive value of electrophysiological parameters were as follows, respectively: %MAF (cut off at 150%, 78%, 52%, 76%), FAZ (cut off at 20 ms, 47%, 84%, 85%), AF threshold (cut off at 10 mA, 94%, 60%, 81%). There were no statistically significant differences between the non‐PAF and PAF groups in the other parameters (effective refractory period, interatrial conduction time, maximum conduction delay, conduction delay zone, repetitive atrial firing zone, wavelength index), that were not specific for PAF. In conclusion, the AF threshold could be a useful indicator to evaluate atrial vulnerability in patients with AF.
Longevity of Dual Chamber Pacemakers: Device and Patient Related Determinants
Authors: KINDERMANN MICHAEL , SCHWAAB BERNHARD , BERG MONIKA , FRÖHLIG GERD
Published: July 2003

KINDERMANN, M., et al.: Longevity of Dual Chamber Pacemakers: Device and Patient Related Determinants. In 382 patients with three different dual chamber pulse generators, the median time interval to battery depletion was 98.3 months. Cox regression analysis revealed the following variables as significant predictors of battery longevity: programmed pacing rate, energy of the stimulation output, mode of stimulation (i.e., proportion of paced cycles in one or two chambers), battery capacity, and internal sensing current of the pacemaker. Although 27% of all patients died before the service life of the pacemaker was over and despite a rate of premature reoperations of 8.6%, the majority of pacemaker patients (55%) fully used the expected battery life span of the pulse generator. Patients who died before the pacemaker had reached its end of service were significantly older at implantation than patients who survived until pacemaker replacement. The vast majority (92%) of patients received another dual chamber pulse generator when replacement was required. These data underline the need for long‐lasting dual chamber devices.
Survey of Cardiac Pacing and Implanted Defibrillator Practice Patterns in the United States in 1997
Authors: BERNSTEIN ALAN D. , PARSONNET VICTOR
Published: July 2003

Bernstein, A.D., et al.: Survey of Cardiac Pacing and Implanted Defibrillator Practice Patterns in the United States in 1997. A survey of implanters of permanent cardiac pacemakers and ICDs in the United States during 1997 was conducted to identify present and changing patterns in indications for pacing, implantation techniques, pacing‐mode selection, follow‐up, and opinions regarding pacing and ICD related issues. This report is an update from 1993 of surveys performed every 4 years for the International Cardiac Pacing and Electrophysiology Society (ICPES). Questionnaires were sent to implanting physicians who were members of the North American Society of Pacing and Electrophysiology (NASPE), and who might, therefore, be expected to be more conversant than others with the state of the art. Four major manufacturers also provided estimates of the numbers of pacemakers and ICDs implanted in the United States from 1994 through 1997. In 1997, approximately 182,000 new rhythm management devices, including 153,000 primary pacing systems and 29,000 ICDs, were implanted, an increase of 24% for pacemakers and 90% for ICDs since 1994. In 1997, pacemaker implantations were performed by about 8,600 physicians working in 3,300 hospitals and 1,000 independent “surgi‐centers.” From 1994 to 1997, sales in the United States of dual chamber pacemakers rose from 58% to 69% of the total, and adaptive rate systems from 74% to 90%. ICD sales increased by about 29% per year from 18,700 to 35,000 units. This study disclosed significant differences among implanter subcategories and between present and earlier practices, and it provided useful insights into trends in pacemaker and defibrillator practice. Future surveys would be facilitated if a standardized implant registry like that used in Europe were established in the United States.
Paradoxical Induction of Cross‐Talk in a Dual Chamber Pacemaker by Increasing the Ventricular Output
Authors: BAROLD S. SERGE
Published: July 2003

BAROLD, S.S.: Paradoxical Induction of Cross‐Talk in a Dual Chamber Pacemaker by Increasing the Ventricular Output. Cross‐talk was induced in a unipolar DDD pacemaker by increasing the output of the ventricular channel. Oversensing by the ventricular channel was probably due to the detection of a relatively large summation signal consisting of the afterpotential and the superimposed activity from the atrial stimulus.
Recurrent Pacemaker Lead Induced Axillary Subclavian Vein Thrombosis
Authors: SWINKELS B.M. , OUDE OPHUIS A.J.M. , ZEGERS E.S. , HERTZBERGER D.P. , MEURSING B.T.J.
Published: July 2003

SWINKELS, B.M., et al.: Recurrent Pacemaker Lead Induced Axillary Subclavian Vein Thrombosis. This report describes a patient with two recurrences of axillary subclavian vein thrombosis more than 1 year after implantation of a permanent transvenous pacemaker. Both recurrences were successfully treated with local thrombolysis.