bluuebunny/crossref_metadata_2025 huggingface dataset:
Normal Values for the Childhood Signal‐Averaged ECG
Authors: DAVIS ANDREW M. , McCRINDLE BRIAN W. , HAMILTON ROBERT M. , MOORE‐COLEMAN PAMELA , GOW ROBERT M.
Published: July 2006

To obtain normative data for the childhood signal‐averaged ECG (SAECG), we obtained SAECGs in 155 volunteers, aged 5–15 years, using Frank leads and a Fourier transform filter. Unfiltered QRS duration (QRSDU) and filtered QRS duration (QRSDF) were significantly longer in males, and the root mean square of the terminal 40 ms (RMS40) was significantly higher in females. There were no gender differences in the duration of high frequency low amplitude signals < 40 μV (DHFLA). All SAECG variables were significantly related to body surface area (BSA), Regression models were established for SAECG variables. For males, the predicted mean + 1.96 standard deviations (SD) for QRSDF (97.5th centile) ranged from 114 ms at BSA 0.70 m2 to 123 ms at 1.90 m2. For females, the predicted mean + 1.96 SD for QRSDF ranged from 110 ms at BSA 0.70 m2 to 119 ms at 1.90 m2. For males and females, the predicted mean + 1.96 SD for DHFLA ranged from 34 ms at 0.70 m2 to 38 ms at 1.90 m2. For males, the predicted mean −1.96 SD (2.5th centile) for RMS40 (based on natural logarithm model) ranged from 30 μV at 0.70 m2 to 15 μV at 1.90 m2. For females, the predicted mean −1.96 SD for RMS40 ranged from 42 μV 0.70 m2 to 20 μV at 1.90 m2. In children 5–15 years of age, both gender and BSA need to be taken into account when interpreting the SAECG.
Electrophysiological, Rate Dependent, and Autonomic Effects of the Class III Antiarrhythmic Almokalant After Myocardial Infarction in the Pig
Authors: TUININGA YPE S. , De LANGEN GEES D.J. , CRIJNS HARRY J.G.M. , WIESFELD ANS C.P. , MOOK PIET H. , BEL KLAAS J. , LIE KONG I.
Published: July 2006

Ventricular arrhythmias remain a major problem, in particular in patients with left ventricular dysfunction or heart failure. In this group of patients, Class I drugs were shown to be ineffective, and they even increased mortality during chronic treatment. New antiarrhythmic agents should preferably not only have pure antiarrhythmic effects, but should also be free from adverse autonomic properties. In the present study, the electrophysiological, rate dependent and autonomic effects of intravenously administered almokalant, a new Class III antiarrhythmic drug, were investigated in nine pigs surviving a myocardial infarction. The ventricular effective refractory period (VERP) increased after almokalant (loading dose: 0.05 μmoLkg −1 .min−1, continuous infusion: 0.0025 uμmol/kg−1.min−1) from 292 ± 25 to 308 ± 13 ms (pacing cycle length [PCL] 500 ms + 1 extrasystole [ES]), from 249 ± 19 to 261 ± 16 ms (PCL 400 ms +1ES), and from 209 ± 18 to 219 ± 18ms (PCL 300 ms +1ES). The VERPs increased most after three ES at PCL 400 ms: from 167 ± 27 to 186 ± 29 ms (P < 0.05) and at PCL 300 ms: from 159 ± 29 to 174 ± 27 ms (P < 0.05). The ventricular monophasic action potential durations (MAPD) were similarly prolonged and the ratio VERP/MAPD did not change. Prolongation of MAPD after almokalant remained present at short pacing cycle lengths. Before almokalant infusion, sustained monomorphic ventricular tachycardia (VT) was inducible in two pigs, and nonsustained VT in a third animal. After almokalant, only one pig remained inducible. Two weeks after myocardial infarction, heart rate variability and baroreflex sensitivity were reduced. Furthermore, subsequent electrophysiological testing transiently reduced these parameters of autonomic activity. During almokalant however, no changes in autonomic functions were observed after programmed stimulation. Heart rate variability decreased after myocardial infarction from 6.3 ± 2.5 ms to 5.4 ± 4,2 ms (P = NS}. After programmed stimulation, it further decreased to 2.8 ± 2.0 ms (P = 0.028). Almokalant infusion prevented autonomic deterioration: 3.3 ± 2.2 ms before stimulation and 3.3 ± 1.3 after stimulation (P = NS). In postinfarct pigs, almokalant prolongs VERP and MAPD at shorter pacing cycle lengths. The results indicate absence of reverse rate dependence and of adverse autonomic changes.
Long‐Term Thresholds of Nonsteroidal Permanent Pacing Leads: A 5‐Year Study
Authors: GUMBRIELLE THOMAS P. , BOURKE JOHN P. , SINKOVIC MATJAZ , TYNAN MARGARET , KITTPAWONG PEERAPONG , GOLD RONALD G.
Published: July 2006

The present commercial market supports many nonsteroidal endocardial pacing leads of differing construction. In order to compare the performance of these configurations, we studied the long‐term pacing properties of three representative lead types by randomized clinical trial in 99 patients undergoing a first elective VVl implant. Thirty‐one patients received sintered platinum leads, 36 activated pyrolytic carbon leads, and 32 vitreous carbon leads. All received generators capable of noninvasive threshold testing. Acute sensing parameters were R wave amplitude and ST segment elevation measured from the endocardial electrogram. Noninvasive voltage thresholds were measured at implantation, 2 days, 1, 3, and 6 months, and yearly thereafter for 5 years. There were no significant differences between leads in pacing or sensing capabilities at implantation. All three demonstrated similar increases in thresholds, peaking at 1 month, then falling to a plateau by 6 months and did not vary significantly thereafter. There were no significant differences in thresholds between leads during 5 years of follow‐up. The lowest mean threshold at 5 years was 0.93 V at 0.5 ms. This study suggests that: (1) although these lead types all perform well, none offers any particular clinical advantage over another; (2) the degree of early threshold peaking precludes immediate postimplant output reduction, but later thresholds are sufficiently low to enable reductions in pacing output; (3) safe low energy pacing requires greater attention to the lead‐generator combinations; (4) data obtained at subsequent annual follow‐up provided no additional useful clinical information to that obtained at 1 year, and (5) in the absence of other differences, cost can be the deciding factor in lead selection.
Problems in Managing Patients with Long QT Syndrome and Implantable Cardioverter Defibrillators: A Report of Two Cases
Authors: PERRY GERSHON Y. , KOSAR EROL M.
Published: July 2006

Implantable cardioverter‐defibrillators (ICDs) have been a successful adjunct to the management of arrhythmias in patients with Long QT syndrome (LQTS). In two patients, interactions between LQTS and the ICD were diagnosed and corrected. Oversensing of T waves was confirmed in the first, while in the second, the arrhythmia disappeared when T wave abnormalities improved after cessation of H2 blocker therapy. In patients with LQTS and an ICD, T wave oversensing should be considered. Interventions that may have an adverse effect on repolarization should be avoided.
Undersensing of the Tiny QRS Complexes That Emerged After the Isolation of the Right Ventricle in a Patient with Ventricular Tachycardia
Authors: GÜLDAL MUHARREM , KARAOǦUZ REMZI , PACIFICO ANTONIO , LAWRIE GERALD M. , AKYOL TURHAN
Published: July 2006

This article describes a patient who underwent right ventricular disconnection for medically refractory ventricular tachycardia associated with arrhythmogenic right ventricular dysplasia. After the operation there was no ventricular tachycardia recurrence. Two years after the operation, he received a permanent VVI pacemaker for the symptomatic second‐degree AV block. Sensing function of the pacemaker was normal for the normal QRS complexes, but the tiny QRS complexes that appeared after the arrhythmia surgery were not sensed by the pacemaker and therefore caused no problem.
Optimal Lead Selection for Detection of ST Segment Shifts
Authors: FULLER MARC S. , DUSTMAN THEODORE J. , SHARP SALLY , GREEN LARRY S. , LUX ROBERT
Published: July 2006

A comparison was made to determine the ability of optimal sets of 2–6 unipolar leads and a normal Holter lead set to estimate ST potential distributions changes induced by balloon inflation during angioplasty. The performance of these lead nets was compared to measurements observed in recorded 32‐lead body surface maps. Unipolar lead potentials were estimated using a linear, least mean squared error estimator of the total body surface map. The correlation between maximum ST potential change in the body surface map and that predicted by the unipolar lead sets ranged from 0.84–0.93. The correlation between maximum ST segment change measured from the body surface map and measured from the Holter leads was 0.29. Therefore, shifts in ST segment potentials can accurately be estimated from a small number of unipolar leads. In contrast, current bipolar ambulatory recording techniques may introduce significant bias to such estimates.
Nonthoracotomy Implantation of Cardioverter Defibrillators: Preliminary Experience with a Defibrillation Lead Placed at the Right Ventricular Outflow Tract
Authors: TANG ANTHONY S.L. , HENDRY PAUL , GOLDSTEIN WILLIAM , GREEN MARTIN S. , LUGE MARILYNN
Published: July 2006

Although morbidity and mortality associated with defibrillator implantation using a nonthoracotomy approach have decreased as compared with a thoracotomy approach, dfifihrillation thresholds have been higher and fewer patients satisfied implan t criteria. It may be possible to improve on the success of nonthoracotomy defibrillator implantation by the placement of a right ventricular (HV) outflow defibrillation lead. Implnntable car‐dioverter defibrillator implantation data of 30 consecutive patients with clinical VT or VF were reviewed. Three defibrillation leads were routinely used. When either pacing threshold at the RV apex ivas inadequate (n ‐ 2) or 18‐J shocks were not successful in terminating VF in 3 of 4 trials (n = 8). the RV apex lead was positioned to the HV outflow tract attaching to the septum. Defibrillation testing was first performed with the RV apex lead in combination with CS, SVC. and/or subcutaneous leads. Twenty patients satisfied implant criteria with a defibrillation threshold of 13.5 ± 3.6 J. In 7 of the 10 patients, whose RV lead was repositioned to the RV outflow tract, this lead in combination with SVC, CS, or subcutaneous leads produced successful defibrillation at < 18 J or in 3 of 4 trials. This approach improved the overall success of nonthoracotomy implantation of defibrillators from 69% to 90%, After a follow‐up of 27 ± 6 months, there was no dislodgment of the HV outflow tract defibrillation leads. Conclusions: This article reports the preliminary observation that placement of defibrillation leads to the RV outflow tract in humans was possible and without dislodgment. RV outflow tract offers an alternative for placement of defibrillation leads, which may improve on the success of nonthoracotomy defibrillator implantation.
Delayed Exercise Rate Response Kinetics Due to Sensor Cross‐Checking in a Dual Sensor Rate Adaptive Pacing System: The Importance of Individual Sensor Programming
Authors: LAU CHU‐PAK , LEUNG SUM‐KIN , LEE IRIS S.F.
Published: July 2006

By cross‐checking the relative sensor activation between a nonspecific and specific sensor during extraneous interference, a multisensor rate adaptive pacemaker may he able to limit inappropriate rate responses. The effects of activity (ACT) sensor programming on rate response kinetics of a QT and ACT dual sensor VVIR pacemaker with sensor cross‐checking algorithm were studied in four patients with atrial fibrillation and complete heart block. The rate adaptive setting of each sensor was individually optimized, and an equal rate contribution for the QT and ACT sensors (QT = ACT) was used in the dual sensor VVIR mode. Three maximal treadmill exercise tests were performed in random order in three different VVIR modes driven by QT only, QT = ACT, and in the dual sensor mode with the most sensitive (low threshold) ACT setting. In the two dual sensor modes, the time for onset of rate response (delay time) was reduced (both < 15 sec) compared with QT only VVIR mode (233 ± 70 sec). However, the time to 50% of rate response in the low ACT threshold dual sensor mode was delayed compared with to QT = ACT (450 ± 110 [95% confidence interval 234–666] vs 311 ± 103 [109–513]sec, P < 0.05) and was similar to the QT only mode (401 ± 120 [l66–636]sec). The time to reach 90% of rate response was similar in the three modes tested. The resting activity counts registered by the ACT sensor were < 5 and 16 ± 2 counts/mm in the optimally programmed and low threshold ACT settings, respectively. This resulted in sensor cross‐checking at rest in the overprogrammed dual sensor VVIR mode, thereby limiting the rate response. Thus, the combined sensor system provides a faster initial response to exercise than the QT only sensor. Programming the ACT threshold to low will prevent this faster response because of sensor cross‐checking.
Effect of Intraatrial Reentry on Initiation of Atrioventricular Reentrant Tachycardia
Authors: ODAKURA HIRONORI , ITO MEIICHI , NAMEKAWA AKIO , YAGI TETSUO , OGATA KAZUNORI , OTOMO JUN , ISHIDA AKIHIKO
Published: July 2006

We studied the effect of intratrial reentry (IAE) on initiation of orthodromic reentrant tachycardia (ORT) in 150 patients with Wolff‐Parkinson‐White syndrome using His‐bundle recording and the atrial extrastimulus technique. IAR was initiated by premature atrial stimulation in 44 patients (29%), and it was followed by ORT in 16 patients (11%). In 8 patients (5%), IAR promoted the initiation of ORT, whereas in 5 patients (3%), IAR inhibited the initiation of ORT. These findings suggest that ORT is frequently induced following IAR. IAR, which was frequently observed during electrophysiological studies, seems to play an important role in the initiation of ORT.
Posterior Left Thoracic Cardiac Sympathectomy by Surgical Division of the Sympathetic Chain: An Alternative Approach to Treatment of the Long QT Syndrome
Authors: EPSTEIN ANDREW E. , ROSNER MICHAEL J. , HAGEMAN GILBERT R. , BAKER JAMES H. , PLUMB VANCE J. , KAY G. NEAL
Published: July 2006

Although high thoracic left Sympathectomy via art anterior surgical approach is a highly efficacious treatment for refractory ventricular arrhythmias in patients with the long QT syndrome, the degree of sympathetic denervation has been variable, success of the operation is influenced by anatomical differences between patients, and Horner's syndrome may result. We hypothesized that interruption of sympathetic input to the heart could be accomplished using a posterior thoracic approach to this variable and often complex anatomy by division of the sympathetic chain rather than by direct destruction of the stellate and superior thoracic ganglia with the more conventional anterior, supraclavicular approach. In addition, the posterior approach should decrease the risk of Horner's syndrome by avoiding the ocular sympathetic efferent nerves. This posterior approach is described in five patients with the long QT syndrome and recurrent ventricular arrhythmias. After a mean follow‐up of 18 ± 12 months, all are alive without Homer's syndrome.
T Wave Alternans in Idiopathic Long‐QT Syndrome: Insight from Body Surface Mapping
Authors: SHIMIZU WATARU , KAMAKURA SHIRO , ARAKAKI YOSHIO , KAMIYA TETSURO , SHIMOMURA KATSURO
Published: July 2006

Body surface mapping was recorded during T wove alternans in two patients with idiopathic long QT syndrome. Eighty‐seven had ECGs of two consecutive beats during T wave alternans demonstrated that alternating changes in the morphology and polarity of the T wave existed mainly in the left frontal chest. The QRST isointegral maps of the same two consecutive beats showed alternation of a large negative area appearing mainly in the left frontal chest. These results indicate that T wave alternans in the two patients were related to alternate heterogeneous prolongation of the action potential duration in this region.
Incidence of Lead System Malfunction Detected During Implantable Defibrillator Generator Replacement
Authors: GOYAL RAJIVA , HARVEY MARK , HORWOOD LAURA , BOGUN FRANK , CASTELLANI MARK , CHAN K.K. , DAOUD EMILE , NIEBAUER MARK , MAN K. CHING , MORADY FRED , STRICKBERGER S. ADAM
Published: July 2006

Implantable cardioverter‐defibrillator (ICD) generator replacement due to a depleted battery is a frequently performed procedure. The frequency with which sensing and defibrillation system failures are identified during device replacement procedures has not been previously described. Therefore, the purpose of this study was to prospectively determine the frequency of lead system malfunction detected at the time of device replacement in 55 consecutive patients undergoing ICD generator replacement. The mean age of the patients was 63 ± 10 years and 40 of them were men. Forty‐nine patients had an epicardial lead system, and six patients had a nonthoracotomy lead system. Four (7%) of these 55 patients were noted to have previously undetected lead system failure, either sensing (n = 3) or defibrillation (n = 1), necessitating system revision. The lead systems that failed were 40 ± 6 months old (33–49 months). In summary, during ICD generator replacement, previously undetected problems with sensing or defibrillation may be identified in approximately 10% of patients. Therefore, a comprehensive evaluation of the sensing and the defibrillation functions should be an essential component of the ICD generator replacement procedure.
A Comparison of Quality‐of‐Life in Patients with Dual Chamber Pacemakers and Individually Programmed Atrioventricular Delays
Authors: FRIELINGSDORF JÜRGEN , DESEÖ THOMAS , GERBER ANDREAS E. , BERTEL OSMUND
Published: July 2006

Dual chamber pacemakers are increasingly implanted to achieve optimal hemodynamics by AV synchrony, but the effect of AV delay programming on the patient's quality‐of‐life has been less well studied. The influence of an individually programmed AV delay between 100 and 250 ms on quality‐of‐life was investigated in a randomized, double‐blind crossover study of 13 patients (69 ± 10 years of age) with dual chamber pacemakers implanted because of high degree AV block. During radionuclide ventriculography at rest, the “optimal AV delay” with the maximal left ventricular ejection fraction and the “most unfavorable AV delay” with the least ejection fraction were determined. The ejection fraction at rest with the “optimal AV delay” was 51%± 10%, and with the “most unfavorable AV delay,” 44%± 11% (P < 0.0001). The optimal AV delay determined by radionuclide ventriculography correlated well with the optimal AV delay determined by Doppler echocardiography using flow velocity integrals (r = 0.78, P < 0.0016). Each patient was assigned in random order to either AV delay during a 2‐week period and then the pacing mode was switched for another 2‐week period. At the end of each period, patients were assessed by a functional status questionnaire to assess physical capability and two further questionnaires to quantify cardiovascular symptoms or self‐perceived health. There were no differences in the two AV delays regarding the patient's perceived physical capability and specific symptoms. The patient's total judgment was identical to the optimal AV delay (score 36%± 19%) and the most unfavorable AV delay (33%± 21%). Thus, in patients with a dual chamber pacemaker, an individually programmed AV delay affects left ventricular function at rest, but has no influence on quality‐of‐life. The determination of the flow velocity integral by Doppler echocardiography is a simple and reliable method to optimize the AV delay if necessary.
Electrophysiological Characteristics of Bipolar Membrane Carbon Leads With and Without Steroid Elution Compared With a Conventional Carbon and a Steroid‐Fluting Platinum Lead
Authors: WIEGAND UWE K. H. , POTRATZ JÜRGEN , LÜNINGHAKE FRANK , TAUBERT GUNNAR , BRANDES AXEL , DIEDERICH KARL‐WERNER
Published: July 2006

In a controlled study, the following four bipolar leads with passive fixation were implanted in 46 patients with the Siemens‐MuItilog‐VVI or Sensolog‐VVIR‐pacemakers: membrane covered activated porous carbon with steroid elution (Siemens 1402 T, 11 patients) and without (Siemens 1403 T, 15 patients); activated carbon (Siemens 1010T, 10 patients); and platinum with steroid elution (Medtronic CapSure 5026, 10 patients). Stimulation threshold (STH) (assessed by a vario‐test), impedance (IMP), and the intracardial R wave potential (IRW) (both gauged by a telemetric method) were measured 1, 5, and 10 days as well as 3 and 6 months after implantation during unipolar and bipolar stimulation, chronaxie rheobase product (CBP) and energy consumption (EC) were systematically determined. Differing insignificantly at the first day after implantation, STH is significantly lower for the 1402 T and CapSure 5026 leads at the tenth day. However, the 1402 T lead shows a significant increase of STH in the follow‐up, in contrast to the other leads. The lowest chronic STH was found in the CapSure 5026 lead (CRP is significantly lower in all other leads, too). IMP is significantly lower in the CapSure 5026 lead compared to 1010 T lead. EC does not differ significantly during chronic stimulation in spite of the best possible programming of pulse amplitude and duration. No significant changes of IRW were observed. Unipolar versus bipolar stimulation shows significantly lower STH, CRP, and IMP, differences of EC and IRW were insignificant. In conclusion, the addition of steroid in membrane covered carbon leads protracts the increase of STH, but does not prevent it. The CapSure 5026 lead shows advantageous stimulation characteristics, but energy consumption is not significantly reduced because of low impedance and impossibility of programming an appropriate low output in Multilog pacemakers.
A Comparative Analysis of Signal Processing Methods for Motion‐Based Rate Responsive Pacing
Authors: GREENHUT SAUL E. , SHREVE ERIC A. , LAU CHU‐PAK
Published: July 2006

Pacemakers that augment heart rate (HR) by sensing body motion have been the most frequently prescribed rate responsive pacemakers. Many comparisons between motion‐based rate responsive pacemaker models have been published. However, conclusions regarding specific signal processing methods used for rate response (e.g., filters and algorithms) can be affected by device‐specific features. To objectively compare commonly used motion sensing filters and algorithms, acceleration and ECG signals were recorded from 16 normal subjects performing exercise and daily living activities. Acceleration signals were filtered (1–4 or 15‐Hz band‐pass), then processed using threshold crossing (TC) or integration (IN) algorithms creating four filter/algorithm combinations. Data were converted to an acceleration indicated rate and compared to intrinsic HR using root mean square difference (RMSd) and signed RMSd. Overall, the filters and algorithms performed similarly for most activities. The only differences between filters were for walking at an increasing grade (1–4 Hz superior to 15‐Hz) and for rocking in a chair (15‐Hz superior to 1–4 Hz). The only differences between algorithms were for bicycling (TC superior to IN), walking at an increasing grade (IN superior to TC), and holding a drill (IN superior to TC). Performance of the four filter/algorithm combinations was also similar over most activities. The 1–4/IN (filter [Hz]/algorithm) combination performed best for walking at a grade, while the 15/TC combination was best for bicycling. However, the 15/TC combination tended to be most sensitive to higher frequency artifact, such as automobile driving, downstairs walking, and hand drilling. Chair rocking artifact was highest for 1–4/IN. The RMSd for bicycling and upstairs walking were large for all combinations, reflecting the nonphysiological nature of the sensor. The 1–4/TC combination demonstrated the least intersubject variability, was the only filter/algorithm combination insensitive to changes in footwear, and gave similar RMSd over a large range of amplitude thresholds for most activities. In conclusion, based on overall error performance, the preferred filter/algorithm combination depended upon the type of activity.
Sudden Death as a Presenting Symptom of Hypertrophic Cardiomyopathy: Treatment with an Implantable Cardioverter Defibrillator
Authors: TALARD PHILIPPE , LÉVY SAMUEL , BONAL JACQUES , PAGANELLI FRANCK , BOUCHIAT CHRISTIAN , CELLARIER G. , DUSSARAT GUY VINCENT
Published: July 2006

Aborted sudden death as the presenting manifestation of hypertrophic Cardiomyopathy in a 14‐year‐old child is reported. Documented ventricular fibrillation was the cause of cardiac arrest. No ventricular arrhythmia was induced during programmed electrical stimulation. An implantable cardioverter‐defibrillator was indicated. As the patient had a family history of myocardial disease, he had undergone a cardiovascular evaluation 4 years before the major event, and was found normal. It is suggested that normal physical examination, ECG, echocardiogram should not rule out the diagnosis of hypertrophic Cardiomyopathy when a family history is present. Left ventricular hypertrophy may develop during childhood in patients with hypertrophic Cardiomyopathy.
Lead Explantation Late After Atrial Perforation
Authors: TRIGANO ALEXANDRE J. , CAUS THIERRY
Published: July 2006

This report describes the case of a patient in whom atrial perforation with penetration of the thoracic wall was diagnosed 2 years after the implantation of an Accufix lead. Despite this complication, atrial detection in the bipolar mode and ventricular pacing were normal. Digital fluoroscopy detected a fracture with extrusion of a short segment of the retention wire. The rupture of the retention wire might have been the result, but was not the cause of the perforation.
Difference in QT Interval Measurement on Ambulatory ECG Compared with Standard ECG
Authors: CHRISTIANSEN JAMES L. , GUCCIONE PAOLO , GARSON ARTHUR
Published: July 2006

Measurement of the QT interval on standard ECG has diagnostic importance in the congenital long QT syndrome, in pharmacological therapy of arrhythmias, as well as in ischemic heart disease. It has been suggested that QT prolongation on ambulatory ECG (Holter) may have similar importance. To assess agreement between methods, QT interval measurement on standard ECG was compared to that on Holter. Simultaneously obtained ECG and Holter tracings (25 mm/s) of the same complexes in leads V1 and V5 were studied in 14 patients (age range 4–36 years). ECG pairs (n = 100, 49 V1 and 51 V5) were compared over a range of QT interval from 300–620 ms, as determined with the use of calipers by two observers blinded to pairing relationship. Correlation between methods was high for both observers (observer 1: r[V1] = 0.872, r[V5] = 0.973; observer 2: r[V1] = 0.972, r[V5] = 0.988), and interobserver variability was small (> 85% of measurements within 20 ms). As compared to ECG, Holter underestimated QT interval in V1 mean difference (QT [Holter]—QT [ECG]) observer 1 (‐23 ms, P < 0.001), observer 2 (‐7 ms, P < 0.05), and overestimated QT in V5, mean difference observer 1 (+ 13 ms, P < 0.001), observer 2 (+13 ms, P < 0.001). However, individual variation between methods was wide, as expressed by the difference between individual measurements (95% confidence interval [V1]: observer 1 [‐99 to +53 ms] observer 2 [‐47 to +33 ms]; [V5]: observer 1 [‐33 to +59 ms] observer 2 [‐17 to +43 ms]). Furthermore, when using the QTA (interval from onset of Q wave to apex of T wave) similar variability was observed. In the assessment of QT interval, potential sources of error of this magnitude could limit the clinical utility of ambulatory monitoring in detecting prolongation of the QT interval for diagnostic purposes.
Diaphragm Pacing with a Quadripolar Phrenic Nerve Electrode: An International Study
Authors: WEESE‐MAYER DEBRA E. , SILVESTRI JEAN M. , KENNY ANNA S. , ILBAWI MICHEL N. , HAUPTMAN SUSAN A. , LIPTON JACK W. , TALONEN PASI P. , GARCIA HONESTO GARRIDO , WATT JOHN W. , EXNER GERHARD , BAER GERHARD A. , ELEFTERIADES JOHN A. , PERUZZI WILLIAM T. , ALEX CHARLES G. , HARLID RICHARD , VINCKEN WOLTER , DAVIS G. MICHAEL , DECRAMER MARC , KUENZLE CHRISTOPH , SÆTERHAUG ARNE , SCHÖBER JOHANNES G.
Published: July 2006

We sought to determine the international experience with the quadripolar diaphragm pacer system and to test two hypotheses: the incidence of pacer complications would be (1) increased among pediatric as compared to adult patients; and (2) highest among active pediatric patients with idiopathic congenital central hypoventilation syndrome (CCHS). Data were collected via a questionnaire coupled with the Atrotech Registry data for a total of 64 patients (35 children and 29 adults) from 14 countries. Thoracic implantation of electrodes and bilateral pacer use each occurred in 94% of all subjects. Tetraplegic (vs pediatric CCHS) patients were more typically paced 24 hours/day (P = 0.001). Pacing duration averaged 2.0 ± 1.0 years among children and 2.2 ± 1.1 years among adults. Infections occurred among 2.9% of surgical procedures, all in pediatric CCHS patients (vs pediatric tetraplegic patients, P = 0.01). The incidence of mechanical trauma was 3.8%, without significant differences among patient groups. The incidence of presumed electrode and receiver failure were 3.1% and 5.9%, respectively, with internal component failure greater among pediatric CCHS than pediatric tetraplegic patients (P < 0.01). Intermittent or absent function of 0–4 electrode combinations occurred among 19% of all patients, with increased frequency among pediatric CCHS than pediatric tetraplegic patients (P < 0.03). Complication‐ free successful pacing occurred in 60% of pediatric and 52% of adult patients. In all, 94 % of the pediatric and 86% of the adult patients paced successfully after the necessary intervention. Although pacer complications were not increased among pediatric as compared to adult patients, the incidence of complications was highest among the active pediatric patients with CCHS. Longitudinal study of these patients will provide invaluable information for modification and improvement of the quadripolar system.
A Randomized, Single‐Blind Crossover Comparison of the Effects of Chronic DDD and Dual Sensor VVIR Pacing Mode on Quality‐of‐ Life and Cardiopulmonary Performance in Complete Heart Block
Authors: DEHARO JEAN‐CLAUDE , BADIER MONIQUE , THIRION XAVIER , RITTER PHILIPPE , PROVENIER FRANK , GRAUX PIERRE , GUILLOT CHANTAL , MUGICA JACQUES , JORDAENS LUC , DJIANE PIERRE
Published: July 2006

The aim of this study was to compare DDD and dual sensor VVIR (activity and QT) pacing modes in complete AV block (CAVB). Eighteen patients (14 men and 4 women, aged 70 ± 6.5 years) implanted with a dual chamber, dual sensor pacemaker for CAVB with normal sinus node chronotropic function were studied. A quality‐of‐life and cardiovascular symptom questionnaire, and a treadmill exercise test were completed after a period of VVIR and a period of DDD pacing, each lasting 1 month. Overall quality‐of‐life and cardiovascular symptoms did not significantly differ, though three patients felt discomfort during VVIR mode. There was no significant statistical difference in Cardiopulmonary parameters. DDD and VVIR modes yielded the following respective data: maximum heart rate = 105.7 ± 21.8 beats/minute versus 107.6 ± 21.6 beats/minute (NS); maximum workload = 60 ± 33.4 W versus 59.3 ± 37.8 W (NS); treadmill duration = 10.1 ± 3.8 minute versus 10.1 ± 3.6 minute (NS); oxygen consumption at anaerobic threshold = 14.6 ± 4.1 ml/kg per minute versus 14.9 ± 4.6 mL/kg per minute (NS); maximum minute ventilation = 49.6 ± 9 L/min versus 46 ± 12 L/min (NS); and respiratory quotient = 1.08 ± 0.15 versus 1.08 ± 0.13 (NS). We conclude that, during a 1‐month follow‐up period, no difference was found between DDD and dual sensor VVIR (QT and activity) pacing modes in CAVB patients with regard to quality‐of‐life and Cardiopulmonary performance, though a trend toward an increased sense of well being was noted with the DDD mode.
Effects of Autonomic Manipulation on Ventricular Fibrillation and Internal Cardiac Defibrillation Thresholds in Pigs
Authors: MORILLO CARLOS A. , JONES DOUGLAS L. , KLEIN GEORGE J.
Published: July 2006

Autonomic tone may contribute to cardiac arrhythmogenesis and influence the efficacy of implantable defibrillators. Fifty‐two anesthetized pigs were randomized to: (1) methacholine (n = 12); (2) nitroprusside (n = 12); (3) phenylephrine (n = 12); (4) carbachol (n = 8); and (5) saline (n = 8). Ventricular fibrillation threshold (VFT) and triplicate defibrillation thresholds (DFT) were obtained before and during each intervention. Mean (± SE) VFT was increased with: methacholine (76 ± 10.6 V vs 39 ± 7.1 V, P < 0.001); phenylephrine (68 ± 10.5 V vs 38 ± 6.2 V, P < 0.001); and carbachol (106 ± 11.5 V vs 30 ± 6.5 V, P < 0.0001). Nitroprusside and saline failed to alter VFT. Mean (± SE) DFT was decreased with: methacholine (7.7 ± 0.8 J vs 9.7 ± 0.8 J, P < 0.001); phenylephrine (9.8 ± 0.9 J vs 11.3 ± 1.0 1, P < 0.05); and carbachol (9.2 ± 0.7 J vs 12.2 ± 0.8), P < 0.0001), remaining unchanged following nitroprusside and saline infusion. Thus, modulation of autonomic tone modified arrhythmia susceptibility and the energy necessary for defibrillation, increased parasympathetic tone, increased VFT, and decreased DFT. Evaluation of autonomic balance, particularly parasympathetic tone, may be useful with the implantation of automatic defibrillators.
Right Ventricular Implantable Cardioverter Defibrillator Lead Implantation Through a Persistent Left Superior Vena Cava
Authors: MARKEWITZ ANDREAS , MATTKE SÖREN
Published: July 2006

A 60‐year‐old woman required implantation of an ICD because of a hypotensive ventricular tachycardia refractory to four different antiarrhythmic drugs. Preoperative diagnostics revealed a persistent left SVC as the only major venous return from the upper part of the body to the heart. Under local anesthesia, a tripolar lead was advanced through the left SVC into the right ventricular apex. Following successful testing, an active can ICD device was implanted, which is functioning well during a follow‐up period of 9 months.
Management of Intracardiac Device Recalls: A Consensus Conference
Authors: GOLDMAN BERNARD S. , NEWMAN DAVID , ERASER JENNIFER , IRWIN MARLEEN ,   the PARTICIPANTS of the CONSENSUS CONFERENCE
Published: July 2006

The incidence of cardiac device recalls seems to be increasing, in part due to increasing complexity, but also due to greater public awareness and regulatory overview. Manufacturers are responsible for postmarket surveillance of their implanted products; evidence for poor performance is usually evaluated by a Physician Advisory Committee (PAC) and unacceptable failure rates or modes prompt the issuance of a recall. A Consensus Conference was held March 6, 1995, in Toronto, Ontario, to discuss the management of cardiac device recalls after the provincial Ministry of Health issued unique guidelines regarding a recent lead problem. Various stakeholders expressed their views and concerns: the federal regulatory body, the provincial Ministry of Health and hospital association, manufacturers, hospital legal counsel, patient and media advocates, and physicians from the United Kingdom, the United States, and Canada. Specific recommendations included: the establishment of a National (or regional) Pacemaker (device/lead) Registry interposed between the manufacturer and the federal authority; the creation of a Recall Task Force (RTF) to deal with specific problems distinct from the manufacturers' PAC; emphasis on patient responsibility for obtaining regular follow‐up and maintaining contact by a pacemaker passport system as exists in Europe: and the fair assignment of costs involved in a recall with specific emphasis on appropriate compensation for physicians and clinic personnel.
Three‐Year Experience with a Stylet for Lead Extraction: A Multicenter Study
Authors: ALT ECKHARD , NEUZNER JÖRG , BINNER LUDWIG , GÖHL KONRAD , RES JOHAN C.J. , KNABE ULF‐HEINRICH , ZEHENDER MANFRED , REINHARDT JÖRG
Published: July 2006

The extraction of chronically implanted and infected pacemaker and defibrillator leads is an important issue. This article describes the experience gathered between 1990 and 1994 by seven European centers regarding a locking stylet that is uniformly applicable for a wide variety of internal pacing coil diameters. This interventional locking stylet for lead extraction has an outer diameter of 0.4 mm (0.016 inches). The stylet consists of a hollow shaft in which an inner traction wire is embedded. At the tip of the inner traction wire an anchoring mechanism, which can be opened by retraction, is applied. Removal attempts were made for 150 leads, 110 in ventricular and 40 in atrial positions. Results: Complete removal was possible in 122 cases (81 %). Partial removal was possible in 18 cases (12%). Failure to remove the lead with the extraction stylet was experienced in 10 cases (7%). In seven patients, the leads were removed by cardiothoracic surgery; 3 defective leads were left in place. There were no serious complications associated with the procedure. None of the patients died. Conclusion: The experience with this extraction stylet for lead removal has shown good results. Despite a low complication rate thus far, each case for lead removal should be judged on the individual basis of benefit‐to‐risk ratio.
Cardiac Pacemakers in Pediatric Heart Transplant Recipients: Incidence, Indications, and Associated Factors
Authors: CHINNOCK RICHARD E. , TORRES VILMA I. , JUTZY ROY V. , JOHNSTON JOYCE K. , LARSEN RANAE L. , RAZZOUK ANEES J. , BAUM MARTI F. , JANNER DONALD L. ,   the PEDIATRIC HEART TRANSPLANT GROUP‐LOMA LINDA
Published: July 2006

This study was undertaken to assess the incidence, indications, and predisposing factors for pacemaker placement in a pediatric heart transplant population. From November 1985 to May 1994, 246 pediatric patients have undergone cardiac transplantation at Loma Linda University Medical Center. Seven (2.8%) have received pacemaker placement with an 8–50 month follow‐up period. Median age at transplant was 462 days (0 days to 2.5 years). The median time to pacemaker placement was 190 days (18–1,672 days) after transplantation. Indications were sick sinus syndrome (SSS) in 5 and heart block in 2 patients (1 during acute rejection). Three patients with SSS underwent electrophysiology studies (EPS); 1 was normal and 2 showed sinus node dysfunction. The mode of pacing was WIR in 6 patients and WI in 1 patient. All 6 survivors are doing well and 5 patients' pacemakers still provide support. These 7 patients were compared with 185 pediatric patients (0 days to 12‐years‐old) transplanted during 1985 through 1993 who survived at least 6 months after transplantation. There was no correlation between the receipt of a pacemaker and graft cold ischemic time, rejection history, donor age, or recipient age at transplantation. The 5 patients with SSS had significantly lower average heart rates in the first month after transplantation (108 ± 16 vs 130 ± 12; P = 0.0002). The need for permanent pacemakers in this population is uncommon. Pacemakers, however, can be safely performed when necessary with excellent clinical results.
Effects of Flecainide, Encainide, and Clofilium on Ventricular Refractory Period Extension by Transcardiac Shocks
Authors: SWEENEY ROBERT J. , GILL ROBERT M. , STEINBERG MITCHELL I. , REID PHILIP R.
Published: July 2006

Objective: The mechanisms by which pharmacological agents alter electrical defibrillation are not fully understood. It has been proposed that, in addition to directly stimulating tissue, defibrillation may involve refractory period extension (RPE) produced by the shock. Accordingly, pharmacological agents might modulate defibrillation by altering RPE. This study examined the effect of Class I and Class III antiarrhythmic agents on RPE by transcardiac shocks. Methods: In four groups of pentobarbital anesthetized dogs, RPE was measured during rapid ventricular pacing before and after administration of either the Class I agents flecainide (n = 7) or encainide (n = 7), the Class III agent clofilium (n = 7), or vehicle (n = 5). Measurements included QRS duration during sinus rhythm and a conduction time, QTC interval and refractory period, and RPE for 4‐ to 10‐V/cm shocks delivered 20–80 ms before the end of the tissue absolute refractory period. For the 6‐V/cm shocks, the interval after the shock during which tissue remained refractory (RIAS) was also computed. Results: Drugs affected QRS duration, conduction time, QTC, and refractory period (without shocks) in accordance with their anticipated Class I and Class III actions. Without drugs, significant RPE was observed in all animals for all shocks delivered 40 ms or less before the end of the refractory period. Clofilium, encainide, and flecainide had a tendency to increase RPE hut only clofilium produced a significant increase. For 6‐V/cm shocks with different timings, the minimum RIAS was found to be approximately 43 ms, and occurred for shocks given 20–30 ms before the end of the refractory period. Conclusions: At drug dosages that produced moderate Class III (=15%) or strong Class I (=35%) effects, only the Class III agent significantly increased RPE and RIAS. Thus, in addition to altering tissue excitability, the effect of antiarrhythmic agents to increase RPE and the minimum RIAS may help explain their influence on defibrillation threshold.
Reduction of Antiarrhythmic Drug Use in Patients Receiving Implantable Cardioverter Defibrillators
Authors: SPERRY ROBERT E. , STAMBLER BRUCE S. , WOOD MARK A. , CYCAN ALAN , ELLENBOGEN KENNETH A.
Published: July 2006

Widespread use of implantable cardiovertfir defibrillators (ICDs) for the treatment of ventricular tachycardia (VT) and ventricular fibrillation (VF) occurred in the late 1980s and early 1990s. Additionally, there has been increasing appreciation during this time for both the lack of efficacy and praarrhythmic activity of antiarrhythmic drugs to treat these cardiac arrhythmias. We evaluated the use of antiarrhythmic drugs from 1987 to 1991 (5‐year period) at the time of ICD implantation in 25,450 patients. The use of all classes of antiarrhythmic agents decreased from 61% to 24% during this time period (P < 0.05), In addition, there was a significant reduction in antiarrhythmic agent use for each drug class (P < 0.05) with the exception of Class II agents (beta blockers). These changes in drug use occurred independent of any changes in age, sex, ejection fraction, prevalence of coronary artery disease, or type of ventricular arrhythmia (VT vs VF).
Within‐ and Between‐Patient Variation of the Signal‐Averaged P Wave in Coronary Artery Disease
Authors: CHRISTIANSEN EVALD HØJ , FROST LARS , PILEGAARD HANS , TOFTEGAARD‐NIELSEN TORSTEN , PEDERSEN ANDERS KIRSTEIN
Published: July 2006

Objectives: To estimate interobserver, within‐patient and between‐patient variation of the signal‐averaged P wave. To determine whether demographic, clinical, conventional ECG information, and coronary angiographic data are associated with the signal‐averaged P wave duration in patients with documented coronary artery disease. Background: A prolonged signal‐averaged P wave may indicate the presence of a substrate for atrial tachyarrhythmias and may predict subsequent development of atrial fibrillation. However, information on variation, reproducibility, and determinants of the signal‐averaged P wave are sparse. Methods: One hundred ninety‐three patients with angiographically documented coronary artery disease underwent two consecutive procedures of signal‐averaging of P waves (SAECG1 and SAECG2). Interobserver, within‐patient, and between‐patient variation of the signal‐averaged P wave was estimated (coefficient of variation: SD/mean). Multiple linear regression analysis was applied to identify parameters independently associated with signal‐averaged P wave duration (SA‐P). Atrial late potentials were considered if SA‐P > 140 ms, and logistic regression analysis was applied to identify parameters associated with the presence of atrial late potentials. Results: The interobserver, within‐patient, and between‐patient coefficients of variation for the signal‐averaged P wave duration were 7.5%, 6.0%, and 8.4%, respectively. The signal‐averaged P wave duration correlated significantly with standard ECG P wave duration and height of the patient (r = 0.59). Forty‐nine percent of the patients had atrial late potentials. P wave duration in the standard ECG correctly classified 73% (140/188) of the patients with respect to atrial late potential positivity or negativity. The sensitivity was 67% and the specificity was 78%. Agreement on the presence or absence of atrial late potentials between two observers was present in 71% (136/193) of the patients, and in 78% (151/193) between SAECG1 and SAECG2. Conclusions: The signal‐averaged P wave has limited reproducibility in patients with coronary artery disease, and a normal or abnormal signal‐averaged P wave can be predicted from the conventional ECG with high accuracy. It is recommended that the signal‐averaged P wave be compared with the standard ECG P wave duration in follow‐up studies with the aim of predicting atrial fibrillation.
Effect of Chronic Oral Moricizine and Intravenous Epinephrine on Ventricular Fibrillation and Defibrillation Thresholds
Authors: PHARAND CHANTAL , GOLDMAN RICHARD , FAN CHENGDE , CHOW MOSES , KLUGER JEFFREY
Published: July 2006

The purpose: of this study was to determine the effects of chronic oral moricizine therapy and physiological doses of epinephrine on ventricular fibrillation and defibrillation thresholds using an implantable transvenous/subcutaneous defihrillation system in a pig model. Thirteen pigs completed the three phases of the study. After a baseline study on day 1, the animals were randomized to receive moricizine 10–15 mg/kg tid or placebo for seven doses, at which time the protocol was repeated on day 4. The same protocol was again repeated on the same day after infusion of physiological doses of epinephrine. Multiple ventricular fibrillation and defibrillation thresholds were measured during each study. Moricizine did not alter ventricular fibrillation nor defibrillation thresholds, whereas epinephrine increased the ventricular defibrillation threshold from 20.8 J to 23.7 J (P < 0.05). In addition, we observed an increase in both ventricular fibrillation (19.7 J vs 12.6 J; P < 0.05) and defibrillation (20.8 J vs 17.8 J; P < 0.05) thresholds over the 4 days of the study. These findings suggest that moricizine may be a safe antiarrhythmic agent to use in patients with implantable cardioverter defibrillators, and that elevated endogenous epinephrine may render defibrillation more difficult.
Inhibition of Bradycardia Pacing Caused by Far‐Field Atrial Sensing in a Third‐Generation Cardioverter Defibrillator with an Automatic Gain Feature
Authors: CURWIN JAY H. , ROELKE MARC , RUSKIN JEREMY N.
Published: July 2006

The diagnostic accuracy of implantable Cardioverter defibrillators may be improved by automatically adjusting gain algorithms, which in general reduce the likelihood of oversensing while maintaining the ability to detect the low amplitude signals associated with ventricular fibrillation. We present a patient with a third‐generation device who developed prolonged ventricular asystole arising as a complication of the automatic gain feature. During asystole the device automatically increased sensitivity in order to prevent undersensing of ventricular fibrillation, which in this case resulted in far‐field sensing of atrial activity and inhibition of ventricular pacing.
Retroperitoneal Placement of an ICD Generator: A Solution for a Difficult Problem
Authors: DEFILIPPI VINCENT J. , GOTTLIEB LAWRENCE , BUMP THOMAS , FERGUSON MARK K.
Published: July 2006

A woman experienced multiple episodes of pocket erosion after placement of an implantable cardioverter defibrillator culminating in a pocket infection. The device was placed in a retroperitoneal location, and the patient has not developed further episodes of pocket erosion or infection. Interrogation of the device in this position and its subsequent replacement have been straightforward.