bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Set Screw and Side‐Lock Connector Reliability
Authors: TYERS G.F.O. , SANDERS R. , MILLS P. , CLARK J.
Published: July 2006

A retrospective review of complications with connectors and lead‐to‐header interfaces was performed following 649 pacing procedures between 1980 and 1990. There were 88 lead revisions (13.6%), 81 device replacements; or modifications (12.5%), and 480 new implants (74%) using devices of five manufacturers. Two basic connector types were studied, one utilizing a set screw and the other using a side‐lock compression fitting. The set screw makes electrical contact and mechanically secures the lead connector pin with a set screw insulated by a self‐sealing grommet or an integral or separate set screw cover. The side‐lock makes electrical contact with an automatic spring mechanism while the plastic lead terminal is secured in the connector block of the pacemaker by a Delrina side‐lock compression fitting. Four hundred fifty‐nine set screw connector devices were followed for up to 12 years with 14 complications(3.1%)whereas 82 side‐lock connector devices were followed for up to 5 years with one complication (1.2%). The set screw and side‐lock connectors were reliable over the period of follow‐up. Although the complication rate appeared lower with the side‐lock, follow‐up was shorter and the number of implants smaller. With the leads used in this study, the side‐lock proved to be a desirable feature due to simplicity, speed, safety, and ease of use. One limitation is the requirement for a precise IS‐1 connector terminal diameter.
The Clinical Relevance of Electromyopotential Oversensing in Current Unipolar Devices
Authors: GROSS JAY N. , PLATT SIMIE , RITACCO ROSEANNE , ANDREWS CAROLYN , FURMAN SEYMOUR
Published: July 2006

Electromyopotential Oversensing of unipolar pacemakers was first appreciated 20 years ago, but its prevalence in present day devices is less well defined. Thirty‐four pacemaker patients, only two with symptoms suggestive of Oversensing, were evaluated in unipolar settings to assess the frequency of provocation of oversensing in one or, if present, both pacing channels. The sensing threshold of each patient, whenever possible, was recorded as well. Results: atrial oversensing occurred in 11/18 patients (61%), all at sensitivities in the 0.4–1.0 mV range. Ventricular oversensing was noted in 13/33 patients (39%), with all but one programmed to settings of 1.25 mV or more sensitive (i.e. < 1.25 mV). Twenty six of 26 patients amenable to testing had ventricular sensing thresholds of at least 4.0 mV or more. Of the 15 patients amenable to atrial sensing threshold testing, 4 had a threshold of 1.0 mV or < 1.0 m V, 6 had thresholds between 1.0–2.0 mV, and 5 sensed at settings > 2.0 mV. Conclusion: electromyopotential oversensing remains a relevant issue in current day unipolar pacemakers. Most patients do not describe symptoms related to electromyopotential interference, yet such interference is frequently provoked. Over‐sensing is common at high sensitivities typically utilized for atrial sensing, but quite unusual at settings necessary for adequate ventricular sensing. Programming unipolar devices to unnecessarily high sensitivities should be avoided or serious consequences may result.
Pacemaker Dependency After Coronary Artery Bypass
Authors: FELDMAN SHLOMO , GLIKSON MICHAEL , KAPLINSKY ELIESER
Published: July 2006

A retrospective study was carried out on 36 patients (33 males and 3 females) to determine the incidence of WI pacemaker dependency following coronary artery bypass surgery. Pacemaker dependency was defined as the presence of pacemaker activity when pacing rate was programmed at 50 beats/min and/or when no hemodynamic adequate rhythm was present during pulse generator replacement. The patients were divided into two groups: (group I) 26 patients with complete atrioventricular (AV) block developing in the early postoperative period. In most of them a pacemaker was implanted up to 3 weeks following surgery (range 2 days to 1 year); (group II) ten patients in whom the indication for pacemaker implantation was sick sinus syndrome with sinus arrest and/or tachy‐bradycardia. These patients underwent pacemaker implantation at varying periods of time following surgery (range 12 days to 4 years). Unipolar endocardial leads with VVI programmable pacemakers were implanted in all patients included in this study. Mean follow‐up time was 3 years. In group I the pacemaker dependency rate was 65%, whereas in group II it was 30% throughout the follow‐up period. It is concluded that the low incidence of pacemaker dependency in patients who undergo pacemaker implantation after coronary bypass surgery necessitates frequent evaluation in the nondependent patient, in order to reassess the need for the pacemaker before pulse generator replacement. Such reassessment should probably include prolonged ambulatory monitoring as well as invasive evaluation of the conduction system, if avoidance of pulse generator replacement is considered.
Incidence and Predictors of Syncope in Paced Patients with Sick Sinus Syndrome
Authors: SGARBOSSA ELENA B. , PINSKI SERGIO L. , JAEGER FREDRICK J. , TROHMAN RICHARD G. , MALONEY JAMES D.
Published: July 2006

In spite of a normal pacemaker/unction, syncope still occurs in some patients with sick sinus syndrome (SSSJ. Causes often remain unknown. To identify predictors and etiologies of this bothersome symptom, we studied 507 patients who received atrial, ventricular, and dual‐chamber pacemakers for SSS. During a mean follow‐up of 62 ± 38 months, actuarial incidence of syncope was 3% at 1 year, 8% at 5 years, and 13% at 10 years. Causes were vasovagal (18%), orthostatic hypotension (25.5%), rapid atrial tachyarrhythmias (11.5%), ventricular tachycardia (5%), acute myocardial ischemia (2.5%), and pacemaker/lead malfunction (6.5%), In 13 patients (29.5%), syncope remained unexplained. The only preimplant predictor for syncope was syncope as primary indication for pacemaker implant. Electrocardiographic correlation with bradycardia was not a predictor of relief of syncope during the follow‐up. In conclusion: (1) syncope in paced patients with SSS has multiple etiologies and may be multifactorial; (2) the only predictor of syncope after pacemaker implant is the occurrence of preimplant syncope as the main indication for pacing; (3) extensive Holier monitoring is not useful to document bradycardic origin of syncope nor to predict its recurrence; (4) SSS probably overlaps with other entities such as autonomic dysfunction, vasovagal syncope, carotid sinus hypersensitivity, and venous pooling, which would provide an explanation for recurrent syncope in patients with normal pacemaker function.
Intravenous Adenosine: A Noninvasive Diagnostic Test for Sick Sinus Syndrome
Authors: RESH WILLIAM , FEUER JOSHUA , WESLEY ROBERT C.
Published: July 2006

Adenosine has a well established negative chronotropic effect on the smoatrial node. The most wideJy utilized test of sinus node/unction remains the sinus node recovery time (SNRT), which generally requires catheterization. We compared the effect of adenosine (150 meg/kg IV) on the lengthening of sinus cycle length (ADO:SCL) in 12 control patients (group I) and in 11 patients with clinical sick sinus syndrome (SSS) (group III, eight of whom had undergone prior permanent pacemaker implantation. Using 675 msec as an abnormal result indicating sinus node dysfunction (two standard deviations above the mean value established in controls), ADO:SCL had a sensitivity and specificity of 64% and 100%, which were equal to that observed for the corrected sinus node recovery time (CSNRT) (abnormal value 550 msec). There was a significant difference in the CSNRT between group I (304 ± 149 msec) and group II (1,199 ±936 msec, P = 0.003). There was no significant difference in ADO:SCL between groups I (256 ± 210 msec) and group II (1,213 ± 1,719 msec, P = 0.069); however, there was substantial overlap between patients exhibiting an abnormal ADO:SCL and CSNRT. As such, a significant difference in ADO.‐SCL was evident between group II patients (1,784 ± 1,950 msec, n = 7) exhibiting an abnormal CSNRT and group I patients, P = 0.014. In conclusion, ADO:SCL has the same sensitivity and specificity for sinus node dysfunction as compared to the CSNRT. Intravenous adenosine may prove to be a useful noninvasive test to assess the need for permanent pacemaker implantation.
A Simple In Vivo Model to Evaluate the Effects of Antiarrhythmic Agents
Authors: SOLOMON ALLEN J. , SYN DAVID , BARBEY JEAN T.
Published: July 2006

Antiarrhythmic agents alter cardiac conduction, refractoriness, and action potential duration in a rate dependent fashion. A simple in vivo model was developed to measure these variables over a wide range of cycle lengths. Complete heart block was produced in dogs using an 8 French hexapolar ablation catheter, anterior skin electrode, and radiofrequency current (30 W, 13,6 ± 2.6 seconds). Ventricular pacing and monophasic action potential recordings were performed using a single combination catheter. QRS and action potential durations were measured at multiple cycle lengths and after an abrupt change in paced cycle length. Ventricular effective refractory periods were also measured at multiple cycle lengths. Data obtained during flecainide and d‐Sotalol infusions are presented. This simple model allows detailed in vivo evaluation of the electrophysiological effects of antiarrhythmic agents and combinations.
Electrogram Patterns Predictive of Successful Radiofrequency Catheter Ablation of Accessory Pathways
Authors: HAISSAGUERRE M. , FISCHER B. , WARIN J.‐F. , DARTIGUES J.F. , LEMÉTAYER Ph. , EGLOFF Ph.
Published: July 2006

We assessed anterograde conduction electrogram parameters at successful ablation sites according to accessory pathway (AP) location and compared them to the most favorable electrograms at unsuccessful sites. A median of three radiofrequency energy impulses was applied to ablate 97% of 136 APs versus four impulses to ablate 90% of 65 concealed APs. Electrograms at successful sites showed variable A/V ratio (0.04‐7), and a QS pattern of unipolar ventricular wave in 90%. Electrograms were different in right versus left AP: AV time 29 ± 7 versus 38 ± 10; and timing of ventricular deflection: 17 ± 9 versus 2 ± 9 msec, respectively. Analysis in each patient of the mapping parameters at successful versus “most favorable” unsuccessful sites showed an improvement in at least one parameter in 55%, no apparent change in all parameter values in 30%, and even less favorable parameters in 15% of patients. In patients with manifest AP, overall comparison of elecfrograms at successful versus unsuccessful sites showed no difference in A/V ratio (1.3 ± 1.5 vs 2.2 ± 1.6), unipolar pattern distribution, and AV time (34 ± 10 vs 35 ± 9), but earlier bipolar main ventricular potential (‐4 ± 12 vs ‐1.5 ± 10 msec) and unipolar intrinsic deflection timings (‐5.2 ± 11 vs ‐1.8 ± 10 msec). In patients with concealed AP, a retrograde continuous electrical activity was recorded in 72% of successful versus 38% of unsuccessful sites (P = 0.03). Conclusions: Electrogram characteristics at successful radiofrequency ablation are different in right and left manifest AP. The timing of the ventricular potential is the only predictive electrogram parameter. Individual analysis of electrograms in each patient shows the better criteria in 55% of successful sites but no improvement in criterion values in 45%.
Changes in Ventricular Effective Refractory Periods After Two Extrastimuli and Ventricular Electrical Instability
Authors: BYTEŠNÍK J. , LEFFLEROVÁ K. , BIČÍK V. , ČIHÁK R.
Published: July 2006

Using programmed stimulation with one and three extrastimuli delivered in the right ventricular apex, we compared the effective refractory period (ERP) during sinus rhythm (ERP‐SR) and during the third extrastimulus (EHP‐S3) in patients without ventricular tachycardias (control group, n = 87) and in patients with documented ventricular tachycardia (VT group, n = 76). The protocol was not completed to determine ERP‐S3 in one patient in the control group and in 15 patients in the VT group. We observed a significantly greater change (i.e., shortening) in ERP after two extrastimuli in the VT group compared with patients without VT (ΔERP = 45 ± 20 msec in the control group and 70 ± 16 msec in the VT group, P < 0.001), This electrophysiological phenomenon, along with conduction delay, may play an important role in VT induction.
Autonomic Manipulation Influences Both Temporal and Frequency Analyses of Late Potentials
Authors: SCHWARTZMAN DAVID , DEMOPOULOS LAURA , SCHREM STANLEY , CARACCIOLO EUGENE , PEREZ JOHN , CHINITZ LARRY , SLATER WILLIAM
Published: July 2006

Previous studies of late potentials have not standardized the autonomic milieu at the time of testing. We studied the effects of autonomic manipulation in seven patients with previous Q wave myocardial infarction. Late potentials were evaluated using standard temporal (TD) and spectral temporal mapping techniques (STM) in the drug free state, and during separate intravenous administration of each of the following: isoproterenol, esmolol, and atropine. Isoproterenol was nitrated to achieve a heart rate of 130% of baseline. Esmolol was infused at a rate of 250 μg/kg per minute, after a loading dose of 500 μg/kg. Atropine was given as a 2‐mg bolus. In addition, five patients who received no drug infusions acted as controls, undergoing four serial signal‐averaging studies in the baseline state: a “baseline” study, and then three additional studies at time intervals similar to those incurred by the study patients. Therefore, a total of 21 TD and 21 STM tests were done in the study group seven patients; three drugs per patient) during the drug infusions, and 15 TD and 15 STM tests were done in the control group (five patients; three “nonbaseline” tests per patient). A change normal to abnormal, or vice versa) in TD during a drug infusion occurred in 24% of the tests. No such change occurred in the control group (P < 0.01). A change in STM during a drug infusion occurred in 38% of tests, versus 13% of tests in the control group (P = 0.14). Overall, six of seven patients had a change in TD and/or STM diagnosis with infusion of one or more of the study drugs. Optimal clinical use of late potentials may require a standardized autonomic environment.
Evaluation of Electrocardiographic Leads for Detection of Atrial Activity (P Wave) in Ambulatory EGG Monitoring: A Pilot Study
Authors: HERZOG LD R. , MARCUS FRANK I. , SCOTT WILLIAM A. , FAITELSON LIONEL H. , OTT PETER , HAHN ELIZABETH
Published: July 2006

The usual lead systems for ambulatory ECG monitoring (AECG) used in the evaluation of arrhythmias is a modified bipolar V‐1 and V‐5. A comparison of various lead systems to enhance the detection of atrial activity (p waves) has not been reported. We evaluated various surface lead systems in 12 subjects comparing p waves recorded at 20 mm/mV and 50 mm/sec. We compared p wave area, amplitude, and duration from modified bipolar V1 and V5 as well as seven nonstandard leads recorded on a AECG monitor. Of the seven nonstandard leads, a vertical sternal lead, with the negative pole just below the suprasfernal notch and the positive pole at the xiphoid process, had the largest area (1.46 ± 0.65 mm2), and also had a greater area than the standard V, (0.88 ± 0.45 mm) and V5, (1.06 ± 0.49 mm2) lead system (P < 0.01). We conclude that the bipolar vertical sternal lead system provides a larger p wave area than seven nonsfandard bipolar lead systems and the two standard lead systems currently used in AECG monitoring. Replacement of the modified bipolar V1 lead with a vertical sternal lead should improve the recognition of atrial activity and, therefore, enhance the diagnosis of cardiac arrhythmias.
Survival in 1,431 Pacemaker Patients: Prognostic Factors and Comparison With the General Population
Authors: JELIĆ VERA , BELKIĆ KAREN , DJORDJEVIĆ MILAN , KOCOVIĆ DUSAN
Published: July 2006

A total of 1,431 patients (mean age 63.4 ± 14.1) with pacemakers (96.2% VVI) primoimplanled between 1967 and 1985 were followed for a mean duration of 78.2 ± 40 pacing months, with 0.6% loss to follow‐up. Cumulative survival for 1, 3, and 10 years was 0.9427, 0.9136, and 0.7536, respectively. There was no significant difference in survival between atrioventricular block (AVB) and sick sinus syndrome (SSS) patients. In addition to age and gender, factors existent prior to implantation that independently affected prognosis included manifest coronary heart disease (CHD), congenital/acquired heart lesions, heart failure, noncardiac internal disease, syncope, and generalized fatigue. After implantation, the most important factor was generalized fatigue, [hen age, stroke, myocardial infarct (Ml), gender (male), heart failure, and syncope. Patients with no underlying disease showed an extremely high cumulative survival (0.9173 at 10 years). Compared to the general population of Yugoslavia, the pacemaker patients showed a similar yearly mortality rate until 1981. After that, elderly males (70+) had a significantly lower yearly mortality than the matched population. Thus, in this large series of pacemaker patients followed into (he most recent period with an extremely low loss to follow‐up, short‐and long‐term survival was very high. Pacemaker patients of any age who are otherwise in good health have an excellent prognosis.
Effects of Oral Propafenone Therapy on Chronic Myocardial Pacing Threshold
Authors: BIANCONI LEOPOLDO , BOCCADAMO ROBERTO , TOSCANO SALVATORE , SERDOZ ROBERTO , CARPINO ARMANDO , IESI ANNA PATRIZIA , ALTAMURA GIULIANO
Published: July 2006

The effects of oral propofenone therapy on pacing threshold were studied in 36 patients chronically paced for sick sinus syndrome or AV block. The pacemakers, all unipolar models and with noninvasive threshold measurement facilities, were: 9 VVI, 15 AAI, and 12 DDD. Each patient received an initial propafenone dose of 450 mg/day, that in 18 cases was increased to 900 mg/day. Threshold was tested at baseline and at each dosage after 7 days of therapy. With the lower propa/enone dosage the threshold, measured at 2.5 V, rose from 0.14 ± 0.10 to 0.21 ± 0.16 msec (+ 55%) in the atrium (P < 0.0001) and from 0.10 ± 0.08 to 0.15 ± 0.09 msec (+ 63%) in the ventricle (P < 0.0001). In the 18 patients who received both dosages, the mean atrial and ventricular threshold increased from 0.12 ± 0.10 to 0.17 ± 0.14 msec with the lower dose and to 0.27 ± 0.22 msec (+125%) with the higher dose (P < 0.0001) for both increments), With the 900 mg/day dose, a threshold increment ± 300% was observed in 15% of the stimulated chambers. A good linear correlation (r = 0.76) was found between the ventricular threshold increment and the drug induced QRS widening. In conclusion, treatment with oral propafenone increases atrial and ventricular stimulation threshold in pacemaker patients. Threshold increment is dose dependent and proportional to the drug induced QHS widening. In the majority of the cases the threshold increment is not clinically significant, but caution must be used in prescribing high doses of the drug to patients with high baseline threshold.
Activity‐Based Pacing: Comparison of a Device Using an Accelerometer Versus a Piezoelectric Crystal
Authors: BACHARACH DAVID W. , HILDEN TIMOTHY S. , MILLERHAGEN JAY O. , WESTRUM BARBARA L. , KELLY JOHN M.
Published: July 2006

The EXCEL(tm) VR, an accelerometer‐based pacemaker (AC), and the Legend(tm), a pacemaker utilizing a piezoelectric crystal (PZ), were compared under ergometric conditions and during stair climbing to assess the appropriateness of their rate responses. The pacemakers, programmed to the manufacturers' nominal settings in order to compare different technologically based sensors under identical conditions, were strapped over subjects' left mid‐pectoral region. Placement of the devices was randomized to control for positionai effects. Ten healthy subjects (55–72 years) completed a graded exercise treadmill test to 80% of maximum predicted heart rate (HR). An additional group often subjects (50–66 years) completed exercise protocols involving bicycle ergometry and stair climbing. Throughout all tests, pacemaker pulse rates and subjects' intrinsic HR were monitored continuously. For the treadmill exercise, the average correlations between the AC and PZ pacemakers' pulse rate and HR for the group as a whole were r = 0.92 and r = 0.82, respectively. Individual subject comparisons were also made between each pacemaker rate and intrinsic HR. The mean difference from intrinsic rate was 11 ppm for the AC pacemaker and 24 ppm for the PZ pacemaker. In addition, the PZ pacemaker's maximal pulse rate was significantly lower (105 ± 9.6 ppm) than the other two rates (AC 137 ± 6 ppm; intrinsic HR 129 ± 2 beats/min). Throughout the bicycle ergometry testing, the intrinsic HR was higher than the AC and PZ pacing rates. However, the AC's rate was significantly higher than the PZ's rate. When subjects ascended stairs, the intrinsic HR and AC rate were closely correlated, but the PZ rate was significantly lower. When subjects descended stairs, neither pacemaker's rate matched intrinsic HR. These results indicate that the AC pacemaker more closely matches intrinsic HR in healthy subjects during ergometric activity and stair climbing than does the PZ pacemaker. Although the three activities evaluated in this study may be lacking representation of other common daily tasks, these results do lend support for considering the use of an AC pacemaker. These data also suggest the need for further research using activity‐based rate‐responsive pacemakers after parameter optimization /or each subject to address issues of sensitivity to and specificity of human movement.
First Derivative of Right Ventricular Pressure, dP/dt, as a Sensor for a Rate Adaptive VVI Pacemaker: Initial Experience
Authors: OVSYSHCHER ILYA , GUETTA VICTOR , BONDY CHAVA , PORATH AVI
Published: July 2006

Ten patients underwent implantation of a rate adaptive ventricular pacing system with a new pulse generator and lead. The unipolar lead has a steroid eluting tip and a pressure sensor. The first derivative of the signal from this sensor, dP/dt, is determined and the pacemaker rate is varied in response to changes in the right ventricular dP/dtMAx. During implantation, dP/dt values were in the range of 180–720 mm Hg/sec, The autothreshold for pacing at 2.5 V remained unchanged 1 month after implantation (0.065 ± 0.045 msec, range 0.05–2.00 msec) and only slightly increased after 3 months (0.075 ± 0.045 msec, range 0.05–2.00 msec). A significant correlation existed between the dP/dt measured during implantation and the right ventricular pressure measured by telemetry at follow‐up visits (r = 0.93, P = 0.0001). Initial pacemaker programming was performed on the second day after implantation following a short walk and was adjusted subsequent to follow‐up visits according to the patient's subjective assessment and in accordance with the results of exercise tests and Holter monitoring. Exercise and Holter tests did not significantly change initial programming. There was a significant correlation between right ventricular systolic pressure and the rate response setting (r = ‐ 0.66, P < 0.05). During dP/dt pacing, all patients felt well, and eight of these reported an improvement compared to non rate adaptive pacing. The heart rate response to effort and recovery was appropriate. It was concluded that: (1) right ventricular dP/dt is a suitable parameter for controlling the pacing rate; (2) appropriate programming of the dP/dt pacemaker results in a suitable heart rate response to exercise and recovery.
Effect of Vagal Nerve Electrostimulation on the Power Spectrum of Heart Rate Variability in Man
Authors: KAMATH M.V. , UPTON A.R.M. , TALALLA A. , FALLEN E.L.
Published: July 2006

The power spectrum of heart rate variability contains low frequency (LF = 0.08–0.12 Hz) and high frequency (HF = 0.18–0.30 Hz) components said to represent neurocardiac rhythms. To verify whether such a relationship exists we report a unique study where the heart rate autospectrum was determined in a 28‐year‐old epileptic male patient with an implanted vagal electrical stimulator. The stimulator was activated at 20 Hz, 300 psec pulse, and 1.25 V. Continuous ECG and respiratory waveform records were obtained over 45 minutes every 8 hours (7–8 AM; 3–4 PM; 11–12 PM) With the stimulator ON, then 24 hours OFF and then 24 hours ON again. The overall LF:HF peak ratio increased from 0.64 to 1.99 (P < 0.001) after the stimulator was turned OFF. There was a dramatic increase in the LF peak power (> 60%) and a corresponding decrease in the HF peak power (> 65%) when the stimulator was turned OFF. These values were reversed when the stimulator was turned ON again. In the early morning and late evening hours, there was a significant rightward shift in the LF peak power frequency (average 0.057 to 0.075 Hz) whenever the stimulator was ON. Otherwise, there were no significant circadian variations in any of the autospectral components. The results demonstrate an unequivocal relationship between selective vagal nerve electro stimulation and alterations in the heart rate autospectrum.
Importance of Recording the Right Bundle Branch Deflection in the Diagnosis of His‐Purkinje Reentrant Tachycardia
Authors: CHIEN WALTER W. , SCHEINMAN MELVIN M. , COHEN TODD J. , LESH MICHAEL D.
Published: July 2006

Eight of 120 consecutive patients with inducible sustained ventricular tachycardia who were studied at our institution from September 1, 1988 to January 1, 1991, were found to have reentry within the His‐Purkinje System as the mechanism of their tachycardias. Two of the eight patients (25%) required the recording of the right bundle branch potential to elucidate the tachycardia circuits. The electrophysiological findings of these two patients are described. In both instances, the diagnosis of supraventricular tachycardia with aberrancy was excluded. In patient 1, a His‐bundle electrogram preceded each QRS complex during tachycardia and the His‐to‐His interval variation preceded changes in QRS intervals. However, recordings from the right bundle branch allowed for exclusion of bundle branch reentry and evidence was found for reentry restricted to the left fascicles. In patient 2, despite instances of dissociation of the His‐bundle deflection from the tachycardia, a right bundle branch potential preceded each QRS and spontaneous changes in the interval between successive activation of the right bundle branch preceded changes in ventricular activation. Catheter ablation of the right bundle branch eliminated the tachycardia. It is concluded that the recording of a right bundle branch potential should be included in electrophysiology study of patients in whom there is suspicion of reentry within the His‐Purkinje System. Clinically, recognizing these forms of tachycardias can be important because they can be effectively treated with catheter ablation.
A Multicenter Experience with a Bipolar Tined Polyurethane Ventricular Lead
Authors: HAYES DAVID L. , GRAHAM KEVIN J. , IRWIN MARLEEN , VIDAILLET HUMBERTO , DISLER GAIL , SWEESY MARK , OSBORN MICHAEL J. , SUMAN VERA J. , NEUBAUER SHARON A. , SEEBANDT MARY , KALLINEN LINDA , CROWSON CYNTHIA S.
Published: July 2006

multicenter study was undertaken to determine the failure rate of a specific polyurethane bipolar lined pacing lead, the Medtronic 4012 pacing lead. Six centers in the United States and Canada implanted 1,190 Medtronic 4012 pacing leads. The study was designed to determine the probability and clinical manifestations of lead failure. Only failures compatible with an insulation problem were included. The probability of a 4012 lead failure by Kaplan‐Meier analysis was 20.9% at 6 years after implantation. Failures were manifested as sensing abnormalities, failure to capture, early battery depletion, and significant decrease in measured impedance compared with the previous impedance measurements. Of the 95 definite lead failures, 16 (16.8%) were associated with symptoms similar to those experienced before pacemaker placement. The observed failure rate is unacceptable, and strong consideration should be given to replacing the 4012 pacing lead in pacemaker‐dependent patients and closely monitoring nonde‐pendent patients.
Clinical Significance of QRS Duration During Ventricular Pacing
Authors: SUMIYOSHI MASATAKA , NAKATA YASURO , TOKANO TAKASHI , YASUDA MASAYUKI , OHNO YASUHIKO , HISAOKA TERUHIKO , OGURA SHUNSUKE , NAKAZATO YUJI , YAMAGUCHI HIROSHI
Published: July 2006

To clarify the clinical significance of an abnormally prolonged paced QRS duration, we studied 114 patients who had undergone pacing for atrioventricular block (AVB). Patients were divided into two groups: group I consisted of 29 patients with at least one paced QRS duration ≥ 180 msec during the follow‐up period; group II consisted of 85 patients with paced QRS durations < 180 msec. The clinical background, QRS complexes before pacing, and the echocardiographic findings were assessed. Males (P < 0.05), those with H‐V block (P< 0.05) and a wider QRS complex of conducted and escape beats (both P < 0.01) were dominant in group I. The incidence of underlying heart disease was greater in group I than in group II (83% vs 32%, P < 0.01). Reduced left ventricular ejection fraction (LVEF) and increased left ventricular end‐diastolic dimension (LVDd) were more prominent in group I than in group II (LVEF 0.49 ± 0.17 vs 0.68 ± 0.10, P < 0.01, LVDd 57.1 ± 7.9 mm vs 48.5 ± 5.6 mm, P < 0.01). The paced QRS duration correlated with LVEF (r = ‐0.61) and LVDd (r = 0.81). A paced QRS duration ≥ 180 msec was sensitive and specific for a LVEF < 0.5 (83.3% and 85.2%) and LVDd ≥ 60 mm (100% and 81.4%). We conclude that patients with a prolonged paced QRS duration have more serious heart disease, and the paced QRS duration can be a useful indicator of impaired LV function.
Retrograde Supernormal Conduction, Gap Phenomenon in Concealed Accessory Atrioventricular Pathways
Authors: SUZUKI FUMIO , HARADA TOMO‐O , NAWATA HIROKO , OHTOMO KEN‐ICHIRO , SATOH TADASHI , HIRAO KENZO , HIEJIMA KAZUMASA
Published: July 2006

We present four patients with the Wolff‐Parkinson‐White syndrome who exhibited retrograde supernormal conduction or gap phenomenon in concealed accessory pathways. In the first patient, ventricular extrastimulus testing revealed retrograde block at the coupling interval of 520 msec and reappearance of conduction at the coupling interval of 370 msec. In a second patient, 1:1 retrograde conduction was not present but supernormal conduction was demonstrated at coupling intervals of 360 msec to 310 msec during the ventricular extrastimulus testing when the basic drive consisted of atrioventricular (AV) simultaneous pacing. In a third patient, ventricular extrastimulus testing demonstrated retrograde conduction through the accessory pathway only at coupling intervals of 400 msec to 360 msec. In a fourth patient, retrograde block occurred at the coupling interval of 340 msec and retrograde “slow” conduction reappeared at coupling intervals of 300 msec to 250 msec (gap phenomenon) only when the basic drive consisted of AV simultaneous pacing. Thus, concealed accessory pathways may exhibit retrograde supernormal conduction or gap phenomenon. Ventricular extrastimulus testing consisting of AV simultaneous pacing during the basic drive may facilitate demonstration of these unusual properties.
Does Dual Chamber or Atrial Pacing Prevent Atrial Fibrillation? The Need for a Randomized Controlled Trial
Authors: LAMAS GERVASIO A. , III N. MARK ESTES , SCHNELLER STANLEY , FLAKER GREGORY C.
Published: July 2006

Partially due to recent reports that cardiac antiarrhythmic therapy may have adverse effects on patient survival, clinicians have become more interested in the nonpharmacological prevention of atrial fibrillation. There is a large body of literature that suggests that the rate of development of atrial fibrillation in paced sick sinus syndrome patients is much lower in those patients who have received an atrial‐based system, rather than a VVI system. However, all the published studies to date are retrospective, and fraught with potential bias favoring the AAI or DDD group. The authors strongly believe that the only way to determine if these suggestive but uncertain retrospective analyses are correct is to apply the same scientific rigor to this problem as has been applied to many other problems in cardiovascular medicine and perform a prospective randomized trial. A proposed trial design is discussed.
Radiofrequency Ablation of Accessory Pathways: Characteristics of Transiently and Permanently Effective Pulses
Authors: CHEN XU , BORGGREFE MARTIN , HINDRICKS. GERHARD , HAVERKAMP WILHELM , KARBENN ULRICH , SHENASA. MOHAMMAD , BREITHARDT GUNTER
Published: July 2006

The purpose of this study was to characterize and compare the radiofrequency current applications that produced permanent or transient accessory pathway conduction block. One hundred fifty‐two radiofrequency energy applications that induced permanent (permanently effective pulses, n = 48J or transient (transiently effective pulses, n = 104) accessory pathway block in 57 patients with 60 accessory pathways were analyzed. The time from the onset of current application to disappearance of preexcitation or termination of supraventricular tachycardia by permanently effective pulses was 1‐15 seconds (mean 3.6 ± 3.8 sec) compared to 2‐29 seconds (mean 11.5 ± 7.5 sec) by transiently effective pulses (P < 0.01). After transiently effective pulses that induced block in accessory pathway, conduction resumed within 5 minutes while induced block by permanently effective pulses persisted in 44 of 48 patients (92%) during follow‐up of 11 ± 12 months. The accessory pathway conduction returned in the remaining four patients after ablation 2 weeks to 7 months. After transiently effective pulses, 41 impulses were delivered to the same site using a higher power output (n = 32) and/or longer energy delivery duration (n = 20) without new mapping of accessory pathway location. Thirty‐six of these impulses again resulted in transient accessory pathway block, four had no effect, only one impulse induced a permanent block in the accessory pathway. Pulses with higher power outputs tended to induce transient effects more frequently than pulses with lower energy. Thus, if block in the accessory pathway during radiofrequency ablation occurs within 5 seconds of current application, and if the accessory pathway block persists over 5 minutes, permanent block of accessory pathway conduction may be expected. If 15 seconds after onset of ablation still no effect is noted, it is unlikely that any permanent effect will occur at longer pulse duration. Therefore, it is not useful to repeat energy delivery after a transiently effective pulse with higher power settings and/or longer pulse duration to the same site without new mapping for localization of the accessory pathway. Further experimental studies are needed to explain the mechanisms of transient effects of radiofrequency pulses.
Hemothorax Associated with Anticoagulation after Placement of Implantable Cardioverter Defibrillator: Possible Similarity to Postinfarction Dressler's Syndrome
Authors: SHAHIAN DAVID M. , VENDITTI FERDINAND J.
Published: July 2006

Massive hemotho‐rax developed after placement of an implantable cardioverter defifarillator (JCD) in two patients who received postoperative anticoagulants. The possible relationship of (his complication to polyserositis after ICD implantation is discussed as are the possible adverse sequelae of early anticoagulation after ICD implantation.
Ventricular Lead Transection and Atrial Lead Damage in a Young Softball Player Shortly After the Insertion of a Permanent Pacemaker
Authors: SCHUGER CLAUDIO D. , MITTLEMAN ROBERT , HABBAL BASSAM , WAGSHAL ALAN , HUANG SHOEI K. STEPHEN
Published: July 2006

We report a case in which permanent pacemaker implantation using a conventional subclavian approach on the throwing side of an avid Softball player resulted in complete transection of the ventricular lead and severe damage to the atrial lead. The site of the lead fracture suggested that both leads were crushed between the clavicle and the first rib as a result of the frequent and repetitive arm movement. This case illustrates the importance of the selection of the correct approach for permanent pacing lead insertion.
Supernormal Conduction in the Left Bundle Branch Unmasked by the Linking Phenomenon
Authors: LUZZA FRANCESCO , ORETO GIUSEPPE , DONATO ANTONINO , SATULLO GAETANO , SCIMONE IGNAZIO M.
Published: July 2006

This presentation reflects a case of phase‐3 left bundle branch block (LBBB). Analysis reveals that relatively early QRS complexes are wide, whereas beats occurring later than a critical time are narrow. There are, however, two unexpected phenomena: (1) an overlap occurs between the range of R‐R intervals resulting in normal intraventricular conduction and the range of R‐R intervals resulting in LBBB pattern. Complexes that follow a wide beat are often wide although they are associated with relatively long R‐R intervals, whereas complexes that follow a normal beat tend to be normal even after relatively short R‐R cycles. This is due to concealed retrograde penetration of the bundle branch that is blocked in anterograde direction (the so‐called linking phenomenon). (2) Some early supraventricular impulses, paradoxically, resulted in normal intraventricular conduction. The phenomenon is a manifestation of supernormal LBB conduction, and only occurs following a wide QRS complex associated with retrograde activation of the LBB. The linking phenomenon reveals or unmasks the supernormal phase of LBB conduction. Following a retrograde and delayed activation of the LBB, the refractory period of the bundle branch is postponed, in such a way that a supraventricular impulse is allowed to occur during the early phase of supernormal conduction.
Atrial Fibrillation: Epidemiology and the Risk and Prevention of Stroke
Authors: Barold S. Serge , KALMAN J.M. , TONKIN A.M.
Published: July 2006

Atrial fibrillation is a common disorder and the incidence increases with each decade of life. Previously, rheumatic mitral valve disease has been the condition most highly associated with atrial fibrillation. However, with the decreasing incidence of rheumatic heart disease, other conditions have assumed greater importance and now congestive cardiac failure, coronary artery disease, and hypertension are the most commonly associated conditions. Nonrheumatic atrial fibrillation is associated with an approximately fivefold increase in the risk of ischemic stroke and a 5% to 7% yearly risk that increases with age. In addition, atrial fibrillation is associated with an increased incidence of silent cerebral infarction and increased mortality. However, whether atrial fibrillation is independently associated with the risk of stroke or is a marker of underlying cardiac disease is contentious. Until recently, the use of preventive therapy has been controversial. However, data from four recently published, prospective randomized studies clearly support the use of warfarin prophylaxis in nonrheumatic atrial fibrillation. Within the diverse group of patients with nonrheumatic atrial fibrillation there are high and low risk subgroups and identification of these may influence decisions regarding antithrombotic prophylaxis. With a few exceptions, however, this remains an area in which there are contradictory findings in the literature. The role of aspirin for prophylaxis in nonrheumatic atrial fibrillation remains unclear and further evaluation awaits the publication of ongoing studies.
A Case of Hidden Receptacle‐Adapter Incompatibility
Authors: NOWAK BERND , VOIGTLAENDER THOMAS , ECKRICH WOLFGANG , BECKER H.‐J.
Published: July 2006

Connection of a universal VS‐1 adapter to a VS‐1 receptacle resulted in intermittent loss of pacing and of sensing in a pacemaker dependent patient. This was caused by the use of an adapter that only provides stable electric contact if the adapter pin is deformed by the set screw. Since we had implanted a pulse generator with a “side‐lock” connector without screws, only a loose connection was achieved. The manufacturers should provide information on such hidden incompatibilities.
Permanent Pacemaker Implantation in the Cardiac Catheterization Laboratory Versus the Operating Room: An Analysis of Hospital Charges and Complications
Authors: STAMATO NICHOLAS J. , OTOOLE MICHAEL F. , ENGER ELAINE L.
Published: July 2006

Permanent pacemakers may be implanted in operating rooms, special procedure laboratories, or cardiac Catheterization laboratories. Previous investigators have shown no difference in efficacy or complications in the operating room versus the cardiac Catheterization laboratory. We retrospectively analyzed the hospital bills of 30 patients undergoing permanent pacemaker implantation at our institution. Group I was 15 consecutive patients implanted in the operating room and group II was 15 consecutive patients implanted in the cardiac Catheterization laboratory, all by the same operators. Hospital charges that were specific to the site of implantation were analyzed. Physician charges for implantation, anesthesiologist, and radiologist charges were not analyzed. There were no in‐hospital complications in either group. The mean charges for group I were $1,856.00 and group II were $1,075.00 (P < 0.001). We conclude that implantation of permanent pacemakers in the cardiac Catheterization laboratory is associated with significantly lower hospital charges compared to implantation in the operating room and has an equally low complication rate.
Adenosine and Verapamil‐Sensitive Ventricular Tachycardia Originating From the Left Ventricle: Radiofrequency Catheter Ablation
Authors: DeLACEY WILLIAM A. , NATH SUNIL , HAINES DAVID E. , BARBER MICHAEL J. , DiMARCO JOHN P.
Published: July 2006

A ventricular tachycardia (VT) with right bundle branch block (RBBB) QRS morphology and left axis originating from the inferoapical segment of the left ventricle is described in a 49‐year‐old man without structural heart disease. This VT could be initiated during isoproterenol infusion and was terminated with intravenous administration of adenosine and verapamil. Radiofrequency ablation eliminated the tachycardia. Previous reports have suggested reentry as the mechanism for a verapamil‐sensitive VT with this EGG morphology, while cAMP‐mediated triggered activity has been proposed as a mechanism for VTs sensitive to adenosine. The latter more typically arise in the right ventricular out flow tract. The electrophysiological and electropharmacological characteristics of the tachycardia in this patient suggest that this VT morphology is not specific for a mechanism but rather for the location of the site of origin.
Reversible Late Potentials Due to Ischemia
Authors: RUBIN DAVID A. , SORBERA CARMINE , COOK JAMES , MCALLISTER ANNEMARIE , BURKE ROBERT M. , WEISS MELVIN B.
Published: July 2006

The role of ischemia in the development of reversible late potentials was assessed in 19 patients undergoing percutaneous transluminal coronary angioplasty. Signal‐averaged electrocardiograms were performed before angioplasty, during ischemia caused by balloon inflation and after angioplasty. Five of 19 patients developed late potentials that reverted to normal after angioplasty. Age, sex, ejection fraction, left ventricular end diastolic pressure, vessels involved, and extent of myocardium in jeopardy did not predict the development of late potentials. Patients with a prior history of myocardial infarction were more likely to develop late potentials. Therefore, patients with prior myocardial infarction appear more likely to develop the substrate for reentrant ventricular tachycardia during periods of ischemia.
Two Different Reentrant Circuits of Ventricular Tachycardia in a Patient with an Extensive Anterior Infarction: Evaluation Using Electrical Catheter Ablation Techniques
Authors: FUJIKI AKIRA , TANI MASANAO , MIZUMAKI KOICHI , SASAYAMA SHIGETAKE , AIZAWA YOSHIFUSA
Published: July 2006

Two morphologically distinct sustained ventricular tachycardias were initiated by programmed stimulation during attempted catheter ablation in a patient with an old anterior myocardial infarction. Right bundle branch block configuration of ventricular tachycardia, which was identical to the spontaneously occurring tachycardia, was initiated and displayed fragmented mid‐diastolic potential at the apicolateral left ventricular site. Evidence of a critical slow conduction area was observed during delivery of electrical stimuli to this area. Following a 150‐joule electrical shock delivered to this area, right bundle branch block pattern of ventricular tachycardia was no longer inducible but a new sustained monomorphic ventricular tachycardia with left bundle branch block pattern was initiated. The mid‐diastolic fragmented activity at the ablation site became electrical activation of bystander area that was not participating in the left bundle branch block type of the ventricular tachycardia circuit. The critical slow conduction area was identified at the apicoseptal left ventricular site that was separated more than 5 cm from the ablation site. We speculate that two morphologically distinct sustained monomorphic ventricular tachycardias may be due to two different reentrant circuits and not the different expression of the same circuit.
A Degenerative Lesion of the Approach to the Atrioventricular Node Producing Second‐Degree and Third‐Degree Atrioventricular Block
Authors: KAWAI SACHIO , FU LONTAI , AZIKI KOUSUKE , OKADA RYOZO , KATOH KAZUZO
Published: July 2006

Second‐Degree and Third‐Degree Atrioventricular Block. We report a case of a degenerative approach lesion in an 83‐year‐old male with diabetes mellitus, hypertension, and ischemia heart disease. His ECGs changed from first‐degree atrioventricuJar (AV) block 14 years ago, to third‐degree AV fA‐HJ block. A pacemaker was implanted for bradycardia. He died 4 years later from heart and renal failure. Serial sections through the conduction system reveaied total depletionandfatty replacement of the atrialmuscie at the approaches to the AV node.
Implantation of a Cardioverter/Defibrillator in the Subpectoral Region Combined with a Nonthoracotomy Lead System
Authors: HAMMEL DIETER , BLOCK MICHAEL , BORGGREFE MARTIN , KONERTZ WOLFGANG , BREITHARDT GÜNTER , SCHELD HANS H.
Published: July 2006

An implantable cardioverter defibrillator was placed into a sub‐pectoral pocket via the incision for cephalic venotomy during implantation of a nonthoracotomy lead system. The approach obviated another incision and subcutaneous tunneling of the leads. There were no perioperative complications and after 6 months of follow‐up, the patient continues to tolerate the device satisfactorily.
Seven Years of Left Ventricular Pacing Due to Malposition of Pacing Electrode
Authors: SHMUELY HAIM , ERDMAN SHIMSHON , STRASBERG BORIS , ROSENFELD JOSEPH B.
Published: July 2006

The case report is presented of a patient in whom an uncomplicated left ventricular transvenous pacing produced right bundle branch block (RBBB). A diagnostic echocardiography, confirmed by cine cardiovascular computed tomography, showed that there was no rupture of the right ventricle and diagnosed a left ventricular pacing, due to malposition of the pacing electrode. The patient was treated with aspirin and dipyridamole during the last 6 years of follow‐up, without any complications, including 1 year of pacing, prior to admission.