bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Mode Switching of Implantable Pacemakers: II. Clinical Performance of Current Algorithms and Their Programming
Authors: LAU CHU‐PAK , LEUNG SUM‐KIN , TSE HUNG‐FAT , BAROLD S. SERGE
Published: July 2003

LAU, C.‐P., et al.: Automatic Mode Switching of Implantable Pacemakers: II. Clinical Performance of Current Algorithms and Their Programming. While the hemodynamic and clinical significance of automatic mode switching (AMS) in patients with pacemakers has been demonstrated, the clinical behavior of AMS algorithms differ widely according to the manufacturers and pacemaker models. In general, a “rate‐cutoff” detection method of atrial tachyarrhythmias provides a rapid AMS onset and resynchronization to sinus rhythm at the termination of atrial tachyarrhythmias, but may cause intermittent oscillations between the atrial tracking and AMS mode. This can be minimized with a “counter” of total number of high rate events before the AMS occurs. The use of a “running average” algorithm results in more stable rate control during AMS by reducing the incidence of oscillations, but at the expense of delayed AMS onset and resynchronization to sinus rhythm. Algorithms may be combined to fine tune the AMS response and to avoid rapid fluctuation in pacing rate. Appropriate programming of atrial sensitivity, and the avoidance of ventriculoatrial cross‐talk are essential for optimal AMS performance.
Permanent Pacemaker Lead Entrapment: Role of the Transesophageal Echocardiography
Authors: CHAMPAGNE JEAN , POIRIER PAUL , DUMESNIL JEAN G. , DESAULNIERS DENIS , BOUDREAULT J‐R , O'HARA GILLES , GILBERT MARCEL , PHILIPPON FRANÇOIS
Published: July 2003

CHAMPAGNE, J., et al.: Permanent Pacemaker Lead Entrapment: Role of the Transesophageal Echocardiography. Numerous complications induced by pacemaker electrodes have been reported. Although mild tricuspid regurgitation is a well‐documented complication of transvenous right ventricular pacemaker leads secondary to abnormal valve coaptation, severe tricuspid regurgitation resulting from perforation of the tricuspid valve itself is a rare complication. This case report details a patient with severe tricuspid regurgitation secondary to impingement of the tricuspid valve by a permanent pacing lead that was diagnosed by transesophageal echocardiography. Surgical repair was advocated because of symptomatic significant tricuspid regurgitation.
Sudden Death Following Rupture of a Right Ventricular Aneurysm 9 Months After Ablation Therapy of the Right Ventricular Outflow Tract
Authors: WOLF DWAYNE A. , BURKE ALLEN P. , PATTERSON KIM V. , VIRMANI RENU
Published: July 2003

WOLF, D.A., et al.: Sudden Death Following Rupture of a Right Ventricular Aneurysm 9 Months After Ablation Therapy of the Right Ventricular Outflow Tract. Aneurysm formation has not been previously described as a complication of radiofrequency ablation. A 49‐year‐old woman with Wolff‐Parkinson‐White Syndrome underwent ablation of abnormal conduction pathways in Koch's triangle and in the outflow tract of the right ventricle. Nine months after the procedure, she died suddenly, and was found at autopsy to have a hemopericardium due to rupture of an aneurysm in the right ventricular outflow tract. The gross and histological features of the aneurysm suggest that it developed because of radiofrequency ablation. The possibility of this potentially fatal complication should be considered during follow‐up evaluation of ablation therapy patients.
A Retrospective Case Study to Assess the Value of the Implantable Loop Recorder for the Investigation of Undiagnosed Syncope
Authors: ASHBY DALE T. , CEHIC DANIEL A. , DISNEY PATRICK J.S. , MAHAR LEO J. , YOUNG GLENN D.
Published: July 2003

ASHBY, D.T., et al.: A Retrospective Case Study to Assess the Value of the Implantable Loop Recorder for the Investigation of Undiagnosed Syncope. If not diagnosed by history, examination, or ECG, the diagnosis of syncope can be difficult with a low yield from echocardiography, ambulatory ECG recording, electrophysiological study, and tilt table testing. During 2 years, 48 patients with unexplained syncope or presyncope from three hospitals in one city underwent the implantation of a Medtronic Reveal implantable loop recorder capable of cardiac monitoring for 14 months. All patients had at least two prior episodes of syncope or presyncope. Fifty‐two percent of patients had electrophysiological studies, all of which were negative. The implantable loop recorder remained implanted until a diagnostic event was recorded, or until the end of the battery life. After a mean follow‐up of 5.6 ± 5.7 months, symptoms reoccurred in 25 (52.1%) patients at a mean of 2.8 ± 2.1 months after insertion of an implantable loop recorder. No further symptoms occurred in 23 (47.9%) patients. Of the 25 patients who had a symptom and recorded an event, an arrhythmia was seen in 10 (40%) patients. Seven patients had bradycardia; 4 with profound sinus bradycardia/sinus arrest, 1 with complete heart block, and 2 in association with the cardioinhibitory component of vasovagal syncope. Three patients had tachycardias; two with supraventricular tachycardia and one with atrial flutter. Fifteen (60%) of the 25 patients who activated their device due to syncope or presyncope were in sinus rhythm during the event. The implantable loop recorder was effective in making a cardiological or noncardiological diagnosis for unexplained syncope or presyncope in 52.1% of the patients.
Errors in Repolarization Measurement Using Magnetocardiography
Authors: SMITH FIONA E. , LANGLEY PHILIP , TRAHMS LUTZ , STEINHOFF UWE , BOURKE JOHN P. , MURRAY ALAN
Published: July 2003

SMITH F.E., et al.: Errors in Repolarization Measurement Using Magnetocardiography. Multichannel magnetocardiography (MCG) noninvasively measures variations in magnetic field strength from many sites at the body surface, potentially providing useful regional information about ventricular repolarization. MCGs contain features similar to ECGs, and although errors associated with repolarization measurement have been quantified for ECGs, no comparative data exists for MCGs. In this study, errors in manual measurement of repolarization interval in the MCG were determined. Sixteen MCG channels and three ECG leads were recorded simultaneously in eight healthy subjects. Each recording was displayed in a random order on a computer screen, in presentations with different noise levels, time display widths, and amplitude display heights. In total, manual measurement of repolarization intervals in 2,048 (eight subjects ×16 channels × eight presentations × two repeats) MCGs were made by each of four analysts. Measured repolarization intervals were reduced by 3 ms when noise was added and by a further 3 ms when this noise was doubled. Intervals were shortened by 9 ms when the time display width was doubled and by a further 10 ms when the display width was doubled again. Measurements increased by 7 ms for a doubling of amplitude display height, equivalent to a doubling of T wave height. There were also consistent differences between analysts; amounting to a greatest mean difference of 24 ms. Display characteristics, added noise, and different analysts thus affect manual repolarization interval measurements in MCG. The errors detected demonstrate the importance of a standard presentation for repolarization measurement in the MCG.
Failure of Atrial Flutter Detection by a Pacemaker with a Dedicated Atrial Flutter Detection Algorithm
Authors: ISRAEL CARSTEN W. , BAROLD S. SERGE
Published: July 2003

ISRAEL, C.W., et al.: Failure of Atrial Flutter Detection by a Pacemaker with a Dedicated Atrial Flutter Detection Algorithm. Detection of atrial flutter may be difficult for pacemakers with automatic mode switching algorithms. The Medtronic Kappa 700 device pacemaker family offers a dedicated Blanked Flutter Search algorithm specifically designed for the detection of atrial flutter. This report describes how spontaneous atrioventricular conduction, resulting in a sensed QRS complex at a critical time, inhibited the function of the Blanked Flutter Search algorithm to sense “concealed” or “blanked” atrial flutter. This observation underscores the need for further refinement of pacemaker algorithms for the detection of atrial tachyarrhythmias.
Right Pneumothorax Resulting from an Endocardial Screw‐In Atrial Lead in an Implantable Cardioverter Defibrillator System
Authors: OGINOSAWA YASUSHI , ABE HARUHIKO , NAKASHIMA YASUHIDE
Published: July 2003

OGINOSAWA, Y., et al.: Right Pneumothorax Resulting from an Endocardial Screw‐In Atrial Lead in an Implantable Cardioverter Defibrillator System. This report describes a rare case of a patient undergoing implantation of a cardioverter defibrillator in whom a right pneumothorax resulting from an endocardial screw‐in atrial lead was observed. Pericardial effusion, substantial changes in lead impedance, and pacing and sensing thresholds were not observed. Pneumothorax disappeared spontaneously and has not reoccurred during follow‐up with conservative therapy alone.
Heart Rate Variability in Arrhythmogenic Right Ventricular Cardiomyopathy Correlation with Clinical and Prognostic Features
Authors: FOLINO ANTONIO FRANCO , BUJA GIANFRANCO , BAUCE BARBARA , THIENE GAETANO , VOLTA SERGIO DALLA , NAVA ANDREA
Published: July 2003

FOLINO, A.F., et al.: Heart Rate Variability in Arrhythmogenic Right Ventricular Cardiomyopathy Correlation with Clinical and Prognostic Features. The identification of subjects with arrhythmogenic right ventricular cardiomyopathy (ARVC) at higher risk for sudden death is an unresolved issue. An influence of the autonomic activity on the genesis of ventricular arrhythmias was postulated. Heart rate variability (HRV) analysis provides a useful method to measure autonomic activity, and is a predictor of increased risk of death after myocardial infarction. For these reasons, the aim of the study was to evaluate HRV and its correlations with ventricular arrhythmias, heart function, and prognostic outcome in patients with ARVC. The study included 46 patients with ARVC who were not taking antiarrhythmic medications. The diagnosis was made by ECG, echocardiography, angiography, and endomyocardial biopsy. Exercise stress test and Holter monitoring were obtained in all patients. Time‐domain analysis of HRV was expressed as the standard deviation of all normal to normal NN intervals (SDNN) detected during 24‐hour Holter monitoring. Thirty healthy subjects represented a control group for HRV analysis. The mean follow‐up was 10.8 ± 1.86 years. SDNN was reduced in patients with ARVC in comparison with the control group (151 ± 36 vs 176 ± 34, P = 0.00042). Moreover, there was a significant correlation of this index with the age of the patients (r =−0.59, P < 0.001), with the left (r = 0.44, P = 0.002) and right (r = 0.47, P = 0.001) ventricle ejection fraction, with the right ventricular end diastolic volume (r =−0.62, P < 0.001), and with the ventricular arrhythmias, detected during the same Holter record used for HRV analysis (patients with isolated ventricular ectopic beats < 1,000/24 hours, 184 ± 34; patients with isolated ventricular ectopic beats > 1,000/24 hours and/or couplets, 156 ± 25; patients with repetitive ventricular ectopic beats (≥3) and/or ventricular tachycardia, 129 ± 25; P < 0.001). During follow‐up two patients showed a transient but significant reduction of SDNN and a concomitant increase of the arrhythmic events. In eight patients an episode of sustained ventricular tachycardia occurred, but the mean SDNN of this subgroup did not differ from the mean value of the remaining patients (152 ± 15 vs 150 ± 39; P = NS). Only one subject died after heart transplantation during follow‐up (case censored). Time‐domain analysis of HRV seems to be a useful method to assess the autonomic influences in ARVC. A reduction of vagal influences correlates with the extent of the disease. The significant correlation between SDNN and ventricular arrhythmias confirmed the influences of autonomic activity in the modulation of the electrical instability in ARVC patients. However, SDNN was not predictive of spontaneous episodes of sustained ventricular tachycardia.
Influence of D‐Net (EUROPEAN GSM‐Standard) Cellular Telephones on Implanted Pacemakers in Children
Authors: ELSHERSHARI HUDA , ÇELIKER ALPAY , ÖZER SEMA , ÖZME ŞENCAN
Published: July 2003

ELSHERSHARI, H., et al.: Influence of D‐Net (EUROPEAN GSM‐Standard) Cellular Telephones on Implanted Pacemakers in Children. This study was designed to evaluate possible interactions between digital cellular telephones and implanted pacemakers in children. The study comprised 95 patients (53 males and 42 females) with a mean age of 11.5 ± 4.6 years (range 1–22 years). The average time from pacemaker implantation was 2.5 years (range 1 month–12 years). Fourteen (15%) devices were dual chamber and the remaining were single chamber pacemakers. The following companies manufactured the pacemakers tested: Medtronic (n = 42), Telectronics (n = 9), Vitatron (n = 16), Pacesetter (n = 19), CPI (n = 8), and Biotronik (n = 1). All the patients were tested in the supine position during continuous ECG monitoring. After completion of the routine pacemaker check, the effects of the European Global system for mobile communication (GSM) was tested using two cellular telephone models (Ericsson GA 628 and Siemens S 25, 2‐W power). For this purpose, atrial and ventricular sensitivity settings were programmed to the most sensitive values, and the tests were carried out in the unipolar and bipolar sensing modes. The evaluation was performed during ringing, switching on/off, and conversation phase with the cellular telephone positioned over the pulse generator and around the pacemaker pocket. A malfunction of the pacemaker was not observed in any patient. Only 1 (1%) of 95 patients showed a brief oversensing problem during calls with the cellular telephone. In this case, an AAIR pacemaker was implanted transvenously in a subcutaneous pocket and the sensing defect occurred only with the unipolar sensing mode and was not reproducible. Once the source of interference was removed, no sensing defect was detected and the patient remained asymptomatic. No symptoms were experienced in this study. The authors believe that pacemaker dependent patients with nonprotected pulse generators manufactured at the beginning of 1990s may be tested by their physicians for possible interferences before they use a digital cellular telephone.
Determinants of Successful Ablation of Idiopathic Ventricular Tachycardias with Left Bundle Branch Block Morphology from the Right Ventricular Outflow Tract
Authors: LEE SHIH‐HUANG , TAI CHING‐TAI , CHIANG CHERN‐EN , HUANG JIN‐LONG , CHIOU CHUEN‐WANG , DING YU‐AN , CHANG MAU‐SONG , CHEN SHIH‐ANN
Published: July 2003

LEE, S.‐H., et al.: Determinants of Successful Ablation of Idiopathic Ventricular Tachycardias with Left Bundle Branch Block Morphology from the Right Ventricular Outflow Tract. The aim of the study was to define the factors that may predict the outcomes of radiofrequency ablation from the right ventricular outflow tract (RVOT) in patients with idiopathic VT with a QRS morphology of LBBB. Endocardial mapping and RF ablation from the RVOT were performed in 35 patients (14 men, mean age 41 ± 14 years), and VT was successfully ablated in 30 patients. There was no significant difference with regard to clinical characteristics and electrophysiological findings between patients with successful and failed ablation. The VTs with successful ablation showed an rS (n = 16) or QS (n = 14) pattern in lead V1, and all five VTs with failed ablation showed an rS pattern in lead V1. Although the absence of an R wave in lead V1 did not differ between patients with successful and failed ablation (P = 0.13), the absence of an R wave in lead V1 predicted VT successfully ablated from the RVOT (positive predictive value 100%; negative predictive value 24%). The VTs with successful ablation had a median precordial transitional zone at lead V4 (range V3–V6), whereas all five VTs with failed ablation had precordial transition zones at lead V3 (P = 0.004). Furthermore, a presence of an R wave in lead V1 associated with a precordial transition zone at lead V3 predicted VT not successfully ablated from the RVOT (positive predictive value 100%; negative predictive value 100%). In conclusion, some VTs with LBBB and inferior or normal axis cannot be ablated from the RVOT. The presence of an R wave in lead V1 associated with a precordial transition zone at lead V3 suggest that some VTs may not arise from the RVOT.
Ventricular Tachycardia as the Initial Manifestation of Ischemia: Documentation of a Mechanism Presaging Sustained Tachyarrhythmias
Authors: VLAY STEPHEN C.
Published: July 2003

VLAY, S.C.: Ventricular Tachycardia as the Initial Manifestation of Ischemia: Documentation of a Mechanism Presaging Sustained Tachyarrhythmias. Nonsustained ventricular tachycardia was the initial and only clinical manifestation of myocardial ischemia in a 64‐year‐old woman evaluated for new onset palpitations. There was no ECG or echocardiographic evidence of ischemia but emergent coronary angiography revealed critical lesions. After angioplasty and stenting of the right coronary artery, ventricular ectopy disappeared. This report documents a mechanism of initiation of sustained ventricular arrhythmias.
Unexpected Loss of Bipolar Lead Function Associated with Lead Connection Design in Dual Chamber Pacemakers
Authors: GORNICK CHARLES C. , ALMQUIST ADRIAN , KALLINEN LINDA , FASHINGBAUER MARGARET , DUNNIGAN ANN , TANG CHUEN , HAUSER ROBERT G. , MILSTEIN SIMON
Published: July 2003

GORNICK, C.C., et al.: Unexpected Loss of Bipolar Lead Function Associated with Lead Connection Design in Dual Chamber Pacemakers. Unexpected loss of bipolar pacing function can occur in Guidant VIGOR dual chamber pacemakers with QC2 (Quick Connect) headers. In a retrospective review of 305 implanted patients, 23 exhibited unexpected loss of bipolar pacing lead function from < 1 to 51 months postimplant. Atrial lead problems were seen in 17 patients and ventricular lead problems in 6 (P < 0.05 atrial vs ventricular). Significant symptoms developed in six patients including two with syncope as a result of noncapture. No significant change in bipolar sensing function was seen. Reprogramming devices to the unipolar mode restored appropriate pacing thresholds and lead impedance. The changes in bipolar lead function are likely caused by failure of the QC2 header lead connection system over time.
Indapamide Induced Syncope in a Patient with Long QT Syndrome
Authors: WANG CHAU‐PING , GUO G. BIH‐FANG
Published: July 2003

WANG, C.‐P., et al.: Indapamide Induced Syncope in a Patient with Long QT Syndrome. A 60‐year‐old woman who had been successfully treated with atenolol and cardiac pacing for hypertension and long QT syndrome developed recurrent episodes of palpitations and syncope. Several days prior to these episodes, indapamide 2.5 mg/day was taken for better control of hypertension. The episodes were associated with prolongation of QT interval and mild hypokalemia (3.1 MEQ/L). Indapamide was immediately stopped, but the QT remained prolonged 2 days later, although the potassium level was normalized. This case suggests that indapamide can cause potassium independent prolongation of the QT interval, resulting in arrhythmia induced syncope.
Anatomy of a Murder: Telemetric Footprints
Authors: MOND HARRY G. , VALENTINE B. CRAIG , RANDALL R. DAVID , KELSALL ROBERT , GREGORY MICHAEL
Published: July 2003

MOND, H.G., et al.: Anatomy of a Murder: Telemetric Footprints. A man with complete heart block received a Pacesetter Affinity pacemaker, programmed DDD. Two months later, the patient was beaten to death and the coroner requested telemetric information. Pacemaker stored Event Records for the previous 40 hours were retrieved and using the zoom scale, the events leading to death were examined. This included sinus tracking during the beating followed by atrial and ventricular pacing interpreted as an unconscious vagal response associated with profound blood loss. Then followed a chaotic rapid ventricular activity or terminal ventricular fibrillation. The telemetric footprints provided valuable time stamps on the events preceding the victim's death.
Temporary Disturbances of the QT Interval Precede the Onset of Ventricular Tachyarrhythmias in Patients with Structural Heart Diseases
Authors: DIEM BJÖRN HENRIK , STELLBRINK CHRISTOPH , MICHEL MATHIAS , SCHAUERTE PATRICK , HANRATH PETER
Published: July 2003

DIEM, B.H. et al.: Temporary Disturbances of the QT Interval Precede the Onset of Ventricular Tach‐yarrhythmias in Patients with Structural Heart Diseases. An increase in sinus rate prior to ventricular tachyarrhythmias has been demonstrated in previous studies. There is no clear data available concerning changes in ventricular de‐ and repolarization prior to ventricular tachyarrhythmias, especially in patients with structural heart disease. Therefore, the aim of this study was to analyze the QT and QTc interval (Bazett's formula immediately before the onset of ventricular tachyarrhythmias in stored electrograms of patients with ICDs. The study analyzed 228 spontaneous ventricular tachyarrhythmia episodes in 52 patients (mean age 64 ± 10 years, 49 men, 3 women) and compared them with 146 electrograms of baseline rhythm recorded during regular ICD follow‐up. Mean ventricular cycle length (CL), QT interval, and QTc were measured before the onset of ventricular tachyarrhythmia and during baseline rhythm. Prior to ventricular tachyarrhythmias onset, CL was significantly shorter than during baseline rhythm (714 ± 139 vs 828 ± 149 ms, P < 0.0001). By contrast, the QT interval (430 ± 67 ms) and QTc interval (518 ± 67 ms) were significantly prolonged before the onset of ventricular tachyarrhythmias as compared to baseline rhythm (QT 406 ± 67 ms, QTc 450 ± 61 ms; P < 0.0001). CL, QT, and QTc changes were independent of concomitant treatment with antiarrhythmic drugs. Ventricular tachyarrhythmias are preceded by a significant prolongation of the QT and QTc intervals. This phenomenon may represent a greater than normal disparity of repolarization recovery times possibly facilitating the development of ventricular tachyarrhythmias.
The Relative Lymphocyte Count Predicts Death in Patients Receiving Implantable Cardioverter Defibrillators
Authors: OMMEN STEVE R. , HAMMILL STEPHEN C. , GIBBONS RAYMOND J.
Published: July 2003

OMMEN, S.R., et al.: The Relative Lymphocyte Count Predicts Death in Patients Receiving Implantable Cardioverter Defibrillators. Although the survival benefit conveyed by the automatic defibrillator has been well established for several subsets of patients, some patients who receive the device still die early. The relative lymphocyte count (%L), a portion of the white blood cell count differential, which is decreased in states of excess systemic stress, has prognostic value in patients with coronary artery disease and advanced heart failure. This study assessed the association of %L with survival in patients receiving automatic defibrillators. A total of 136 consecutive patients (81% men; mean age 64 ± 12 years) who were using automatic defibrillators were followed for 29.6 months. The mean ejection fraction was 0.36 ± 0.17, the mean %L was 22.7 ± 8%, and 55 (40%) patients had decreased %L (< 20.3%). There were 20 deaths, for a 4‐year survival of 71.5%. The association of %L with time to death was assessed by Cox proportional hazards analysis. Ejection fraction (P = 0.005), %L (P = 0.01), and diagnosis (P = 0.03) were independently associated with time to death on multivariate analysis. One‐year and 4‐year survival rates were 93% and 54%, respectively, for the 55 patients with abnormal %L, compared with 99% and 84%, respectively, for the 81 with normal %L (P = 0.03). This suggests that the %L is a readily accessible prognostic marker in patients using automatic defibrillators. This association is independent of age, sex, diagnosis, and ejection fraction.
ST‐Segment Deviation Following Implantable Cardioverter Defibrillator Shocks: Incidence, Timing, and Clinical Significance
Authors: GUREVITZ OSNAT , LIPCHENCA IGOR , YAACOBY ELAD , SEGAL ERAN , PEREL AZRIEL , ELDAR MICHAEL , GLIKSON MICHAEL
Published: July 2003

GUREVITZ, O., et al.: ST‐Segment Deviation Following Implantable Cardioverter Defibrillator Shocks: Incidence, Timing, and Clinical Significance. ST‐segment analysis is frequently used during surgical procedures, while ST deviation is considered a sign of myocardial injury. ST deviations were reported following transthoracic and epicardial electrical shocks. The prevalence, timing, and clinical significance of ST‐segment deviation following endocardial ICD shocks are discussed in this article. Twenty‐eight patients undergoing 125 shock episodes during ICD implantation or testing were included. A 12‐lead ECG was recorded at baseline, continuously during the first 3–10 seconds, 1 minute after test shocks, 3–10 seconds and 1 and 5 minutes after each shock given to terminate VF. ST deviation was diagnosed when the ST‐segment was displaced ≥ 1 mm in at least one lead compared to baseline. ST‐segment deviations were observed after 49 (39%) of all shock episodes in 17 (61%) of patients. ST elevation was observed after 30 (24%) of all shock episodes, and ST depression after 31 (25%). Following 13 shock episodes in seven patients, ST‐elevation and depression were observed. ST depressions occurred more frequently after shocks given to terminate VF than after lower energy test shocks (28% vs 18% respectively, P = 0.045). However, there was no significant difference in the prevalence of ST elevations between the lower or higher energy shocks. No adverse clinical events were observed in patients with or without postshock ST‐segment deviation. ST‐segment deviation following endocardial ICD shocks is a frequent phenomenon, occurring acutely and resolving during the first few minutes postshock. It may have no prognostic implications.
Inhibition of Bradycardia Pacing and Detection of Ventricular Fibrillation Due to Far‐Field Atrial Sensing in a Triple Chamber Implantable
Authors: VOLLMANN DIRK , LÜTHJE LARS , GÖRTLER GEORG , UNTERBERG CHRISTINA
Published: July 2003

VOLLMANN, D., et al.: Inhibition of Bradycardia Pacing and Detection of Ventricular Fibrillation Due to Far‐Field Atrial Sensing in a Triple Chamber Implantable Cardioverter Defibrillator. Oversensing of intracardiac signals or myopotentials may cause inappropriate ICD therapy. Reports on far‐field sensing of atrial signals are rare, and inappropriate ICD therapy due to oversensing of atrial fibrillation has not yet been described. This report presents a patient with a triple chamber ICD and a history of His‐bundle ablation who experienced asystolic ventricular pauses and inappropriate detection of ventricular fibrillation due to far‐field oversensing of atrial fibrillation. Several factors contributed to the complication, which resolved after reduction of the ventricular sensitivity.
Catecholaminergic Polymorphic Ventricular Tachycardia in a 3‐Year‐Old with Occult Myocarditis
Authors: BRYANT RANDALL M. , REDFEARN SHARON P. , MARANGI DON , DAVENPORT JOSEPH P. , KUNTZ SEAN T. , SCHOWENGERDT KENNETH O.
Published: July 2003

BRYANT, R.M., et al.: Catecholaminergic Polymorphic Ventricular Tachycardia in a 3‐Year‐Old with Occult Myocarditis. Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare clinical entity in children. Occult myocarditis has not been previously implicated as an etiologic agent. A 3‐year‐old female presents with a presumed breath‐holding spell and is found to have ventricular fibrillation requiring DC cardioversion. An invasive electrophysiological study was performed demonstrating the absence of inducible ventricular arrhythmias. Low dose epinephrine confirmed the presence CPVT. Right ventricular endomyocardial biopsies sent for polymerase chain reaction (PCR) analysis demonstrated the presence of adenoviral DNA. The authors hypothesize that occult myocarditis may be the inciting agent for CPVT in children.
Efficacy of Metoprolol and Sotalol in the Prevention of Recurrences of Sustained Ventricular Tachyarrhythmias in Patients with an Implantable Cardioverter Defibrillator
Authors: KETTERING KLAUS , MEWIS CHRISTIAN , DÖRNBERGER VOLKER , VONTHEIN REINHARD , BOSCH RALPH F. , KÜHLKAMP VOLKER
Published: July 2003

KETTERING, K., et al.: Efficacy of Metoprolol and Sotalol in the Prevention of Recurrences of Sustained Ventricular Tachyarrhythmias in Patients with an Implantable Cardioverter Defibrillator. ICDs provide protection against sudden cardiac death in patients with life‐threatening ventricular arrhythmias. Nevertheless, most ICD recipients receive adjunctive antiarrhythmic drug therapy to reduce the number of recurrent episodes and ICD discharges. The aim of the study was to compare the efficacy of metoprolol and d,l‐sotalol in preventing VT/VF recurrences in patients with an ICD in a prospective, randomized trial. One hundred patients (83 men, 17 women; mean age 59 years, SD ± 11 years) were randomized to receive metoprolol or sotalol after implantation of an ICD. There were no significant differences between the two groups with regard to age, sex, underlying cardiac disease, left ventricular ejection fraction, NYHA class assessment and clinical arrhythmia. The median follow‐up was 728 days (25th percentile: 530 days, 75th percentile: 943 days) in the metoprolol group and 727 days (25th percentile: 472 days, 75th percentile: 1,223 days) in the sotalol group (P = 0.52). Thirty‐three patients treated with metoprolol and 30 patients receiving sotalol had at least one episode during the follow‐up. Event‐free survival curves were generated for the two treatment arms using the Kaplan‐Meier method and showed no significant difference (P = 0.68). Eight patients treated with metoprolol and six patients treated with sotalol died during follow‐up. Total mortality was not significantly different between the two study groups (P = 0.43). Metoprolol is as efficacious as sotalol in preventing VT/VF recurrences in patients with an ICD.
1‐Year Performance of a Defibrillation Lead with a Small Electrode Surface for High Impedance Pacing: A Randomized, Controlled Study
Authors: VOLLMANN DIRK , STEVENS JENS , ZENKER DIETER , KRIEGLSTEIN HOLGER , UNTERBERG CHRISTINA
Published: July 2003

VOLLMANN, D., et al.: 1‐Year Performance of a Defibrillation Lead with a Small Electrode Surface for High Impedance Pacing: A Randomized, Controlled Study. A small electrode surface reduces pacing current drain and can extend generator longevity. The study evaluated the performance of a tined, quadripolar defibrillation lead (model 6944) that has a small‐surfaced, steroid‐eluting electrode tip for high impedance pacing. In a prospective, controlled study, 34 patients with conventional ICD indications were randomized one to one to receive the high impedance model 6944 or a tined defibrillation lead with a conventional sized, steroid‐eluting electrode tip model 6942. Lead performance was evaluated at implant, prior to hospital discharge, and 1, 3, 6, and 12 months thereafter. Baseline characteristics did not differ significantly between patients implanted with lead model 6942 (n = 16) or model 6944 (n = 17). One patient randomized to receive the model 6942 was excluded from the study and was implanted with an active‐fixation lead after stable lead positioning was neither possible with the 6942 nor with the 6944 electrode. No other lead related adverse events were observed. At implant, there were no significant differences between pacing thresholds, sensing performance, defibrillation impedances, and defibrillation thresholds in both groups, but pacing impedance of the model 6944 (988.6 ± 217.7 Ω) was approximately twice as high as in the model 6942 (431.7 ± 83.7 Ω; P < 0.0001). This difference remained highly significant throughout the observation period of 12 months, while R wave amplitudes and pacing thresholds remained equal in both lead models. The use of a tined defibrillation lead with a small, steroid‐eluting electrode tip appears safe and results in a high pacing impedance without compromising system performance.
Temporal Changes in the Endocardial ST Segment During the Evolution of Myocardial Infarction in Dogs
Authors: LESSICK JONATHAN , WOLF TAMIR , GEPSTEIN LIOR , HAYAM GAL , BEN‐HAIM SHLOMO A.
Published: July 2003

LESSICK, J., et al.: Temporal Changes in the Endocardial ST Segment During the Evolution of Myocardial Infarction in Dogs. Acute coronary occlusion causes ST‐segment elevation on the body surface ECG and on the epicardial electrogram in the territory supplied by that artery. The occurrence and significance of endocardial ST changes have not been studied. The NOGA electromechanical mapping was performed on eight anesthetized dogs at baseline, immediately after occlusion of the LAD, and again at 5 hours to assess regional changes in the ST segment. At 3 days and 4 weeks the ventricles were remapped for comparison. Regional unipolar ST‐segment elevation was measured for each zone from NOGA maps at 0, 80, and 120 ms after the J point. ST segments rose immediately in the infarct zones, as demarcated by echocardiography, compared to remote zones, but by 3 days had dropped below, and at 4 weeks returned to baseline values. Immediately postocclusion, ST elevation at 120 ms best differentiated between normal versus abnormal echo scores (concordance = 0.80), probably by correcting for pressure induced ST elevation. In conclusion, acute endocardial ST‐segment changes occur in the infarct zone in the dog, showing a distinctive temporal evolution.
Compatibility of Automatic Threshold Tracking Pacemakers with Previously Implanted Pacing Leads in Children
Authors: KUCUKOSMANOGLU OSMAN , CELIKER ALPAY , OZER SEMA , KARAGOZ TEVFIK
Published: July 2003

KUCUKOSMANOGLU, O., et al.: Compatibility of Automatic Threshold Tracking Pacemakers with Previously Implanted Pacing Leads in Children. The Autocapture function controls and optimizes the amplitude of the pacing pulse and saves energy. The manufacturer recommends using a special low polarization, low threshold bipolar Pacesetter lead for the Autocapture function. The purpose of this study was to evaluate the compatibility of Autocapture with previously implanted pacing leads. The study included 15 patients (mean age 13.6 ± 3.4 years) who needed pulse generator replacement and received the VVIR pacemaker Regency SR+ or the DDDR pacemakers Affinity DR or Integrity DR with the Autocapture function. The new pulse generators connected to previously implanted ventricular leads. At the time of implantation the pacing threshold was 1.0 ± 0.35 V at 0.5 ms, the lead impedance was 580 ± 80 Ω, and the spontaneous R wave amplitude was 7.89 ± 4.89 mV. The polarization signal (PS) was 3.8 ± 3.04 mV, and evoked response (ER) was 8.15 ± 4.57 mV at the predischarge testing. Follow‐up telemetry was done at months 1, 3, 6, 12, and 18. The follow‐up duration was 9.4 ± 5 months (range 1–18 months). If the results of PS and ER measurements were acceptable for Autocapture, it turned on at the 1‐month visit. In six (40%) patients the results were found acceptable for Autocapture function. Age, lead impedance, pacing threshold, intrinsic R wave measurement, lead age, fixation mechanism, and ER measurements were not statistically different in Autocapture suitable and not suitable groups. The main reason not to activate Autocapture had been increased PS. Any significant fluctuations were not observed in pacing threshold, lead impedance, ER, and PS during follow‐up. In conclusion, previously implanted pacing leads may be compatible with the Autocapture function.
Implantable Cardioverter Defibrillator Proarrhythmia Due to an Interaction with “Noncompetitive Atrial Pacing”: An Algorithm to Prevent Atrial Arrhythmias
Authors: CRON THOMAS A. , SCHAER BEAT , OSSWALD STEFAN
Published: July 2003

CRON, T.A., et al.: Implantable Cardioverter Defibrillator Proarrhythmia Due to an Interaction with “Noncompetitive Atrial Pacing”: An Algorithm to Prevent Atrial Arrhythmias. An episode of device related proarrhythmia observed with a dual chamber ICD is reported. Ventricular tachycardia was induced due to an inappropriate interaction of programmed device settings with automatic algorithms, including noncompetitive atrial pacing (NCAP), an algorithm used to prevent atrial tachyarrhythmias.
A View from Down Under: Laparoscopic Look at a Subrectus Pacemaker
Authors: EPSTEIN MICHAEL R. , INGE THOMAS H.
Published: July 2003

EPSTEIN, M.R., et al.: A View From Down Under: Laparoscopic Look at a Subrectus Pacemaker. This article describes an infant with multiple congenital anomalies who underwent laparoscopic insertion of a gastrostomy tube. Prior repair of congenital heart defects had resulted in complete heart block necessitating the implantation of an epicardial pacemaker. A photograph taken within the peritoneal cavity provides a unique view of the patient's subrectus pulse generator.
Single Lead DDD Pacing Using Electrodes with Longitudinal and Diagonal Atrial Floating Dipoles
Authors: IZQUIERDO RICARDO , RODRIGO GONZALO , PELEGRIN JUANA , SÁNCHEZ ANTONIO , FAJARDO RICARDO , VIDAN JUAN , FERREIRA IGNACIO
Published: July 2003

IZQUIERDO, R., et al.: Single Lead DDD Pacing Using Electrodes with Longitudinal and Diagonal Atrial Floating Dipoles. In this study, an assessment was made of the possibilities of single lead DDD pacing in two groups: a group of 15 patients in whom a lead with a longitudinal atrial “floating” dipole was implanted, and another group of 10 patients with a lead with a diagonal atrial “floating” dipole. In both groups, the electrodes were connected to a SLD generator. At discharge, atrial capture was achieved with the unipolar mode in 17 of 25 patients, whereas in the group carrying the longitudinal atrial dipole, atrial capture was achieved with the overlapping biphasic impulses (OLBI) system in 12 of 15 patients and in all 10 patients in the group with the diagonal atrial dipole. At 3 months, atrial capture was achieved with the unipolar mode in 13 of 22 patients (5.75 ± 1.77 V/0.5 ms), whereas with the OLBI system atrial capture was achieved in 8 of 13 patients carrying the longitudinal atrial dipole (3.11 ± 1.13 V/0.5 ms), and in 8 of the 9 patients carrying the diagonal atrial dipole (2.80 ± 0.69 V/0.5ms). In this study, the use of the OLBI system led to a significant reduction of atrial threshold (P < 0.0001). Phrenic stimulation is the main untoward effect reported during single lead DDD pacing, a lower incidence being detected in the group carrying the diagonal atrial dipole (10 vs 35.7%, P = NS). Other limitations of this form of pacing could result from a crossed stimulation phenomenon detected in a patient during single lead DDD pacing.
Ventricular Rate Stabilization for the Prevention of Pause Dependent Ventricular Tachyarrhythmias: Results from a Prospective Study in 309 ICD Recipients
Authors: GRÖNEFELD GERIAN C. , ISRAEL CARSTEN W. , PADMANABHAN VASANT , KOEHLER JODI , CUIJPERS ANTOINE , HOHNLOSER STEFAN H. ,   THE WORLDWIDE GEM DR STUDY GROUP
Published: July 2003

GRÖNEFELD, G.C., et al.: Ventricular Rate Stabilization for the Prevention of Pause Dependent Ventricular Tachyarrhythmias: Results from a Prospective Study in 309 ICD Recipients. Reviews of stored electrograms from ICDs revealed a 5–30% incidence of short‐long‐short intervals preceding the onset of recurrent ventricular tachyarrhythmias. Rate stabilization by dedicated antibradycardia pacing algorithms has, therefore, been suggested to prevent onset of pause dependent tachyarrhythmias. However, the clinical efficacy of this approach has not been studied systematically. In a prospective multicenter crossover study, patients were randomized to activation or deactivation of an implemented ventricular rate stabilization algorithm (VRS) after first implant of a dual chamber ICD. After 3 months, all patients were crossed over to the alternate programming. The rate of appropriate spontaneous VA episodes was compared between VRS On and VRS Off. Stored electrograms were reviewed for evaluation of the mode of onset of tachyarrhythmias. Overall efficacy analysis was based on 309 patients enrolled in the study. Forty percent (124/309) of the patients experienced 4,973 VA episodes. Based on an intention‐to‐treat analysis, VRS Off and On arrhythmia incidence was 10.2 and 6.6 normalized to 3 months, respectively (risk reduction 35%; P = 0.18) On an on‐treatment basis, a reduction from 9.0 episodes to 8.1 episodes (10% risk reduction, P = 0.24) was seen. In an extended Cox model adjusting for confounding variables, the relative risk for recurrent episodes was 0.92 during VRS On compared to Off (95% CI: 0.58–1.48; P = 0.74). During VRS Off, pause dependent onset was documented in only 36 (8%) of 427 visually analyzed episodes. There was no significant reduction in the incidence of recurrent ventricular tachyarrhythmias with VRS On compared to the Off programming in this prospective study.
Isochronal Difference Mapping: An Approach for Mapping Dynamic Changes During Reentrant Ventricular Tachycardia
Authors: CIACCIO EDWARD J. , LEE TAEHOON
Published: July 2003

CIACCIO, E.J., et al.: Isochronal Difference Mapping: An Approach for Mapping Dynamic Changes During Reentrant Ventricular Tachycardia. During clinical electrophysiological study for treatment of reentrant ventricular tachycardia, activation maps constructed from the acquired electrophysiological data can be difficult to interpret when the reentrant circuit is changing from one cardiac cycle to the next. Reduction of complexity would be beneficial but has been difficult. A new technical method termed isochronal difference mapping (IDM) was devised to reduce complexity and enhance distinctive conduction patterns present in the data. Electrograms were acquired from 196 sites using a canine model of a reentrant ventricular tachycardia circuit with a figure eight conduction pattern occurring in the epicardial border zone. Activation maps were constructed for all cardiac cycles during episodes of tachycardia in five experiments. IDM maps were then created, which are subtractive comparisons of the activation maps from two different cardiac cycles during a given tachycardia episode. In each map the electrical activation occurring for only one or for both of the cardiac cycles was separately highlighted in distinct spatial areas of the border zone during an isochronal interval. Based on the mappings, areas of conduction velocity change, regions of breakthrough of the wavefront across functional lines of block, regions with coherent activation, and regions with irregular activation became readily apparent. IDM maps showed that when cycle length prolonged due to deceleration of conduction within the reentrant circuit isthmus, conduction velocity increased elsewhere in the circuit. IDM accentuates cycle‐to‐cycle differences in multichannel electrophysiological data and can be used to reduce complexity and enhance distinctive conduction patterns.
The Reliable Electrocardiographic Diagnosis of Regular Broad Complex Tachycardia: A Holy Grail That Will Forever Elude the Clinician's Grasp?
Authors: LAU ERNEST W. , NG G. ANDRÉ
Published: July 2003

LAU, E.W., et al.: The Reliable Electrocardiographic Diagnosis of Regular Broad Complex Tachycardia: A Holy Grail That Will Forever Elude the Clinician's Grasp? The reliable and accurate diagnosis of regular broad complex tachycardia (BCT) by the ECG is a goal that has eluded clinicians and electrophysiologists alike for years. This article explores the reason for this by first giving an historical account on the development of the subject. Next, the electrophysiological mechanisms of ventricular tachycardia, supraventricular tachycardia with aberrant conduction, and preexcited tachycardia, the three main differential diagnoses for regular BCT, according to the latest knowledge from cellular and clinical electrophysiology study will be reviewed, together with considerations on how such understanding may help account for the manifestations of these tachycardias on the ECG and the difficulty in distinguishing between them. Finally, the use of electrophysiological study as the criterion standard for diagnosing regular BCT, as has been the case in most studies on the subject, will be critiqued in terms of the potential for misdiagnosis by the method and the use of any ECG diagnostic algorithms developed with its aid in the acute medical care setting.
Split Atrial Electrograms Recorded During Dual Chamber Pacing
Authors: SHAH PRASAD , VEALE‐MORELLO CAROL , CAMERON DOUGLAS , STEEVES JIM , HARRIS LOUISE
Published: July 2003

SHAH, P., et al.: Split Atrial Electrograms Recorded During Dual Chamber Pacing. Split atrial electrograms (AEGs), as a measure of intraatrial conduction delay, have been previously identified during electrophysiological studies and as such, may be related to the development of atrial tachyarrhythmias. This article reports the finding of split AEGs observed in two patients with implanted dual chamber pacemakers. The event marker and the surface electrogram identified these AEGs by using and interpreting the intracardiac AEG derived from the atrial pacing lead.
Development of an Echocardiographic Method for Choosing the Best Fitting Single‐Pass VDD Lead
Authors: YIN WEI‐HSIAN , JEN HSU‐LUNG , CHIANG MENG‐CHENG , CHUANG YI‐CHENG , CHANG CHUNG‐YI , YOUNG MASON SHING , WEI JENG
Published: July 2003

YIN, W.‐H., et al.: Development of an Echocardiographic Method for Choosing the Best Fitting Single‐Pass VDD Lead. To achieve stable single‐lead VDD pacing, a selection of the electrode with the optimal distance between the lead tip and the floating atrial dipole (AV distance [AVD]) is important. The authors hypothesized that the size of the right heart chambers may affect atrial sensing, and that measurement of their internal dimension at end‐diastole (RHIDd) in the apical four chamber view by transthoracic echocardiography may aid in choosing the proper AVD. Twenty‐six consecutive cases that had undergone VDD pacer implantation using the conventional chest X ray were examined retrospectively by the echocardiographic method. The chest x‐ray method properly selected a lead with optimal atrial sensing, defined as minimum P wave amplitude ≥ 1.0 mV, for only 20 (77%) of 26 patients. By comparing these results with their respective RHIDd, a cut‐off point of 13 cm was obtained that indicated a criterion for choosing the proper AVD. The indication was that if the RHIDd was ≥ 13 cm, a lead with an AVD of 15.5/16 cm should have been used; if the RHIDd was < 13 cm, a lead with an AVD of 13/13.5 cm should have been chosen. Using the echocardiographic method, all six patients who had suboptimal atrial sensing could be identified and classified as having missized (four undersized; two oversized) permanent leads. In conclusion, the described method provides a promising preoperative assessment of the best fitting electrode length in single lead VDD pacing. A prospective study is ongoing to verify its applicability.