bluuebunny/crossref_metadata_2025 huggingface dataset:
Catheter Ablation for Patients with Cardiac Arrhythmias
Authors: SCHEINMAN MELVIN M.
Published: July 2006

Catheter ablative techniques have recently been introduced as therapy for patients with drug‐resistant cardiac arrhythmias. These techniques include delivery of high‐energy direct‐current shocks in order to electrocoagulate the atrioventricular junction for those with supra ventricular arrhythmias. This technique, if successful, results in arrhythmia control but induces chronic pacemaker dependency. The evidence, to dale, suggests that 90% of these patients are improved after attempted atrioventricular junctional ablation. Catheter ablative procedures have been used for attempted ablation of accessory pathways and has been shown to be especially effective for those with posteroseptal accessory pathways. More recently, techniques for ablation of ventricular tachycardia foci have been introduced but experience with this procedure is too limited to allow for definitive recommendations.
Septal Origin of Sustained Ventricular Tachycardia in a Patient with Right Ventricular Outflow Tract Obstruction After Correction of Tetralogy of Fallot
Authors: SWERDLOW CHARLES D. , OYER PHILIP E. , PITLICK PAUL T.
Published: July 2006

Right ventricular hypertension and ventricular arrhythmias are risk factors for sudden death after correction of tetralogy of Fallot, but sustained ventricular tachycardia has been reported only in patients without residual hemodynamic abnormalities. A patient with right ventricular hypertension and hypotensive ventricular tachycardia tolerated the arrhythmia better after relief of right ventricular outflow tract obstruction. This case provides insight into the relationship between hemodynamic abnormalities and the clinical consequences of arrhythmias. To our knowledge, it is the first report of ventricular tachycardia originating in scar adjacent to the ventricular septal defect patch after correction of tetralogy of Fallot.
Atrial Pacing via Unilateral Persistent Left Superior Vena Cava
Authors: ROBBENS ERWIN J. , RUITER JAAP H.
Published: July 2006

A patient who suffered from sinus node dysfunction and automatic atrial tachycardias underwent pacemaker implantation during which time a unilateral left superior vena cava was found. Despite the known difficulties in using this venous route, it was possible to place a transvenous endocardial screw‐in lead in a stable position in the lower lateral wall of the right atrium.
Catheter Atrioventricular Junctional Ablation in Patients with Accessory Pathways
Authors: ELDAR MICHAEL , GRIFFIN JERRY C. , SEGER JOHN J. , ABBOTT JOSEPH A. , RUDER MICHAEL A. , DAVIS JESSE C. , HERRE JOHN M. , SCHEINMAN MELVIN M.
Published: July 2006

Seven patients with accessory pathway and symptomatic alrioventricular reciprocating tachycardia underwent catheter ablution of the atrioventricular junction (AVJ). Four patients had the Wolff‐Park inson White syndrome, two had concealed left free‐wall accessory pathways, and one patient had a nodoventriculor connection. All patients failed multiple antiarrhythmic drugs and one failed attempted surgical ablation of a posteroseptal accessory pathway. Chronic interruption of atrioventricular node‐His conduction was achieved in all patients. Over a mean follow‐up period of 21 ± 14 months, four patients remained asymptomatic without antiarrhythmic therapy. One patient developed atrial fibrillation after magnet application to her VVI pacemaker, another developed atrial gutter, and a third had nonparoxysmal sinus or atrial tachycardia. Two patients required chronic quinidine therapy. Two patients with concealed accessory pathways had pacemaker‐mediated tachycardia which was controlled by pacemaker reprogramming. Atrioventricular junctional ablation in patients with accessory pathways proved elective in that all are currently controlled without need for surgical intervention. On follow‐up, a relatively high incidence of atrial arrhythmias requiring antiarrhythmic therapy was found.
Progressive Atrioventricular Block During Exercise in Univentricular Heart
Authors: ALBOLIRAS ERNERIO T. , PORTER COBURN J. , RITTER DONALD G. , DANIELSON GORDON K. , DRISCOLL DAVID J.
Published: July 2006

Two patients who had univentricular heart presented with complaints of recurrent nausea and vomiting during exertion. Exercise study revealed 1:1 atrioventricular conduction and no symptoms at rest; at peak exercise, both patients experienced progressive, high grade, second degree atrioventricular block and nausea. Both patients underwent permanent pacemaker implantation, with relief of symptoms. Exercise testing is important in evaluating patients who are at increased risk of spontaneous atrioventricular block, and exertion‐induced nausea may be a clue to its presence.
Ventricular Parasystole: A Chronobiologic Study
Authors: LANZA GAETANO ANTONIO , LUCENTE MICHELE , REBUZZI ANTONIO GIUSEPPE , SPAGNOLO ANTONIO , DULCIMASCOLO CALOGERO , MANZOLI UGO
Published: July 2006

Previous works have reported circadian rhythms for several cardiovascular parameters. A chronobiologic rhythm is characterized by: mesor (a rhythm‐determined average), amplitude (half difference between the highest and lowest values), and acrophase (timing of high point in degrees and/or in hours) along with 95% confidence limits. We performed 24‐hour ECG Holler monitoring in seven patients (mean age, 50.6 years) with ventricular parasystole (VP) in order to determine whether the chronotropic activity of parasystolic foci has a circadian rhythm similar to that of the sinus node. For each Holter recording parasystolic rates (PRs) and heart rates (HRs) were calculated every hour. Furthermore, a mean hourly PR and a mean hourly HR were calculated from the hourly PRs and HRs of the patients. The statistic chronobiologic analysis was done by single and mean cosinor methods. Correlation between mean hourly PR and HR was evaluated by Pearson's V coefficient. A statistically significant rhythm (P < 0.05) was found for the single and mean rhythms both of HR and PR. In our patients, HR had acrophase at 1.27 P.M., mesor at 73.28 beats/min, and amplitude at 9.53 beats/min, whereas PR had acrophase at 1.42 P.M., mesor al 38.31 beats/min, and amplitude at 3.64 beats/ min. Chronobiological data and the high direct correlation between mean hourly HRs and mean hourly PRs (r = 0.96, P < 0.001) indicate a similar circadian variability of the chronotropic activity of sinus nodes and parasystolic foci. Although several hypotheses can be made, responsiveness of parasystolic foci to circadian variations of the autonomic nervous system tone (sympathetic and/or vagal) and/or circulating substances (particularly catecholamines) seems the more probable one for explaining our findings.
The Role of Animal Models in Electrophysiologic Studies of Life‐Threatening Arrhythmias
Authors: DAVID DANIEL , MICHELSON ERIC L. , DREIFUS LEONARD S.
Published: July 2006

Animal models have made substantial contributions to the understanding of basic electrophysiologic principies and arrhythmia mechanisms, as well as to the deveJopment of antiarrhythmic drugs, devices and procedures. The field of clinical electrophysiology has progressed very dramatically and there have also been advances in the basic laboratory that bear relevance In the methods, design and inferpretafion of clinical electrophysioiogic testing, and to the application of new, potential antiarrhythmic interventions.
Reflex Cardiac Asystole
Authors: KOFFLAKD MARCEL , DE BOER HANS , VAN MECHELEN ROB
Published: July 2006

In this report we present the case of a patient with recurrent syucopal episodes. During one of the attacks the patient was monitoring by telemetry and the ECC lead showed asvstole for more than 7 seconds. As in cases of the carhlinhibitory type of hypersenstive carolid sinus svndrome [HCSS]. asvstole may represent suppression of the sinus node or suppression of both sinus and atioventricular [AV] node. Unfortunately, in contrast to HCSS, there is no maneuver that can reproducibly induce episodes of asystole. Consequentlty, very little is known about the occurrence of AV block in the presence of sinus arrest. In the patient described in this report. We were able to demonstrate that suppression of sinus and AV nodes occured simultaneously. This is interesting to note that in this type of syneope data from noninvasive and invasive techniques in assessing sinus nodal and AV nodal conduction may note be conclusive. In the group of patients with this type of syncope, permanent artial demand pacing is constraindicated.
Sensors in Pacing
Authors: ANDERSON K.M. , MOORE A.A.
Published: July 2006

Sensor driven pacing is emerging as a powerful therapeutic tool to provide paced patients with a more natural heart rhythm, and, additionally, piezoelectricity is one technology that can provide sensed information to the pacemaker—and shows promise in controlling that rhythm.
Rate Responsive Dual Chamber Pacing
Authors: KAPPENBERGER LUKAS J. , HERPERS LOEK
Published: July 2006

We report about a new pacemaker, which simultaneously offers dual chamber pacing in DDD Mode and activity controlled rate response. The system also uses activity‐sensing to differentiate true sinus tachycardia from ectopic atrial activity or atrial fibrillation and therefore prevents pacemaker mediated arrhythmias. The clinical experience proves appropriate functioning of all technical aspects of the device. Preliminary noninvasive hemodynamic assessments confirm improvement in cardiacjunction with AV synchronous pacing mode and demonstrate the ouporiority of rate‐responsive dual chamber versus single ventricular pacing.
Rate Adaptive Pacing—Clinical Experience with Three Different Pacing Systems
Authors: MAISCH BERNHARD , LANGENFELD HEINER
Published: July 2006

Physiological stimulation can be achieved by either bifocal or rate responsive pacing. The latter pacemakers adapt the heart rate to physical activity by biological signals. Out of many possible approaches only three pacemaker systems for rate responsive pacing are available: the QT‐pacemaker (Tx or Quintech), the respiratory biorate pacemaker, and the activity detecting Activitrax. Our own experiences (8 QT, 6 Biorate, 8 Activitrax pacemakers) and a survey of 95 QT‐ and 37 Biorate pacemakers from 11 centers are reported. The Biorate pacemaker functions without any problems; its present disadvantage is limited programmability. With the Tx pacemaker failing, frequency adaptation (26%) was found more often in the early series, mostly due to voltage polarization at the tip of the electrode. The Activitrax pacemaker gives satisfactory frequency adaptation, largely depending on the activity of the muscles of the shoulder and pectoral region.
Rate Responsive Pacemakers: Assessment after Two Years
Authors: ZEGELMAN M. , BEYERSDORF F. , KREUZER J. , CIESLINSKI G.
Published: July 2006

Rate responsive pacemakers (RRPM) for patients without sufficient response of the heart rate (HR) to exercise represent an alternative to improve cardiac output (CO) and capacity for exercise via an increase of HR. From 1983 until December 1985, we implanted 30 QT‐related (TX), 25respiratory dependent (RDP), and 35 body activity directed (ACT) pacemakers. The follow‐up examination consisted of Holter‐ECG, treadmill and/or bicycle workload, and determination of CO (TX: thermodilution technique, n = 11; 6 months after implantation. RDP: equilibrium radionuclide ventriculography, n = 13; 1 month after implantation). The capacity for exercise of patients with ACT was studied using a climbing step. Adaptation of HR could be achieved with TX. RDP, and ACT. There was a significant increase in CO during exercise TX or RDP versus VVI‐mode (TX: δ= 1.7l/min, RDP: δ= 2.1 l/min).Although all systems exhibited weak points, RRPM are reliable devices. We abide by using these pacemakers.
Interatrial Conduction During Cardiac Pacing
Authors: AUSUBEL KALMAN , KLEMENTOWICZ PETER , FURMAN SEYMOUR
Published: July 2006

DDD pacemakers sense and pace right‐sided cardiac chambers. The relationship of atrial to ventricular systole on the left side of the heart is of importance for systemic hemodynamics. Effective atrioventricular synchrony is partially determined by interatrial conduction time (IACT). At the time of DDD pacemaker implantation, interatrial conduction was measured using an intraesophageal pill electrode in 25 patients who were on no cardiac medications. Mean interatrial conduction time for all patients prolonged from 95 ± 18 ms during sinus rhythm to 122 ± 30 ms during right atrial pacing (p < 0.001). In 16 patients with P wave duration < 110 ms interatrial conduction prolonged from 85 ± 10 ms during sinus rhythm to 111 ± 9 ms during right atrial pacing (p < 0.01) compared to 114 ± 20 ms prolonging to 111 ± 19 ms (p < 0.01] in 9 patients with P wave duration > 110 ms. In each patient, while atrioventricular conduction prolonged with incremental right atrial pacing, interatrial conduction times did not vary. Interatrial conduction prolongs from baseline during atrial pacing and remains constant at all paced rates from 60–160 heats per minute. In addition to longer interatrial conduction times during sinus rhythm, patients with electrocardiographic P wave prolongation have longer interatrial conduction times during right atrial pacing than do normals (p < 0.0001). Based on interatrial conduction times alone, the AV interval during DDD cardiac pacing should be approximately 25 ms longer during AV pacing as compared to atrial tracking.
Physiological Relationship Between AV Interval and Heart Rate in Healthy Subjects: Applications to Dual Chamber Pacing
Authors: DAUBERT CLAUDE , RITTER PHILIPPE , MABO PHILIPPE , OLLITRAULT JACKY , DESCAVES CHRISTIAN , GOUFFAULT JACQUES
Published: July 2006

The purpose of this paper is to specify the mathematical relationship between spontaneous AV interval (AVI) and heart rate (HR), the amplitude and rate of variation of AVI, and the physiological factors likely to affect these characteristics. Ten patients with healthy hearts were studied. Two catheter electrodes were positioned in the right atrium and at the tip of the right ventricle respectively, allowing the detection of endocardial signals. The AV and AA intervals for each heart cycle were digitized to on accuracy of ± 1 msec. Measurements were made at rest, then during a stress test on an exercise bicycle, and finally during the recovery phase. The results show that adaptation is very precise and takes place instantly. Any variation in heart rate causes an immediate, inversely proportional variation in AVI. Adaptation follows a linear pattern, generally with relatively low amplitude and an average AVI reduction of 27.5 ±11.2 msec for an average HR increase of 78.7 ± 22.5 bpm, i.e., a decrease of 4 ± 2.1 msec for an HR variation 0f 10 bpm. The amplitude and variation rate of AVI seem to be independent 0f the age and base value of the PR interval. These observations may be useful for designing new VDD or DDD pacemakers that automatically adapt the AV interval to the instantaneous heart rate. The hemodynamic benefits 0f this adaptation were also demonstrated.
Prediction of Wenckebach Behavior and Block Response in DDD Pacemakers
Authors: STROOBANDT ROLAND , WILLEMS ROGER , HOLVOET GERMAIN , BACKERS JOS , SINNAEVE ALFONS
Published: July 2006

At higher atrial rates, the behavior of a DDD pulse generator will depend on the atrial rate or spontaneous atrial interval (SAI) and the settings of the pacemaker: upper rate interval (URI), atrioventricular interval (AVI), and atrial refractory interval (ARI). An algorithm was developed enabling the prediction of the degree of Wenckebach block using the parameters mentioned above. In the absence of the programmed settings of the pacemaker, these parameters can be determined by noninvasive methods. AVI can be measured by application of a magnet over the pulse generator, while URI and ARI can be estimated during chest wall stimulation by progressively increasing the frequency of the external extrastimuli. The use of the formula in combination with chest wall stimulation allows the evaluation of the proper functioning of any DDD pacemaker during exercise and in patients with atrial rhythm disturbances, even when no information about the pacemaker settings is available.
The Dynamic Nature of Ventriculoatrial Conduction
Authors: KLEMENTOWICZ PETER , AUSUBEL KALMAN , FURMAN SEYMOUR
Published: July 2006

An endless loop tachycardia starts when the atrial sensory amplifier of a dual chamber pacemaker identifies an early atrial signal originating from a ventricular or atrial premature depolarization or from myopotential noise. The tachycardia will continue as long as ventriculoatrial conduction is sustained. By selecting the appropriate atrial sensitivity setting, postventricular atrial refractory period, or upper rate limit, it is possible to eliminate sustained endless loop tachycardia. Electrophysiological data obtained at the time of dual chamber pacemaker implantation can assist the physician when selecting these settings. This report summarizes our intraoperative data on ventriculoatrial conduction obtained from 432 consecutive patients. One hundred sixty‐two patients had evidence of ventriculoatrial conduction including 14% of patients with antegrade complete heart block and 32% with 2:1 AVB. The majority of patients with preserved antegrade conduction had sustained retrograde conduction. During incremental ventricular pacing, ventriculoatrial conduction prolonged in the majority of patients, and with faster ventricular pacing rates, ventriculoatrial block developed. Ventriculoatrial block developed in half of the patients at a ventricular pacing rate exceeding 120 bpm. Analysis of these data suggests that by selecting an upper rate limit of 140 bpm, a postventricular atrial refractory period of 300 msec, and an atrioventricular interval of 125 msec, approximately 90% of patients will not have sustained endless loop tachycardia.
A Single Atrial Extrastimulus Can Distinguish Sinus Tachycardia from 1:1 Paroxysmal Tachycardia
Authors: JENKINS JANICE , NOH KI HONG , BUMP THOMAS , MUNKENBECK FRANCES , BROWN JEFFREY , ARZBAECHER ROBERT
Published: July 2006

We have developed a tachycardia detection scheme for use in an antitachycardia pacemaker in which the use of a properly timed atrial extrastimulus provides a means of discriminating sinus tachycardia from pace‐terminable 1:1 tachycardias. An atrial extrastimulus is delivered in late diastole (80 ms premature), and the ventricular response is monitored. In sinus tachycardia, the ventricular response is expected to appear early as well, but in pace‐terminable tachycardias, such as AV reentrant and ventricular with VA conduction, the ventricular rhythm will be unperturbed. Testing of the algorithm was performed in 34 patients. In 29 patients, atrial extrastimuli were delivered during sinus tachycardia, and in 22 patients during various types of 1:1 paroxysmal tachycardia. In one patient the procedure was completely automated, i.e., delivery of the atrial extrastimuli and diagnosis were microcomputer controlled. In 28/29 cases, the delivery of an atrial extrastimulus 80 to 120 ms early during sinus tachycardia elicited a ventricular response at least 28 ms early. In 22/22 patients with 1:1 paroxysmal tachycardia, atrial extrastimuli 80 to 120 ms early failed to produce a significant change in ventricular cycle length. This technique appears to be promising for prevention of inadvertent pacing of sinus tachycardia in an antitachycardia pacemaker.
Clinical Evaluation of Automatic Tachycardia Diagnosis by an Implanted Device
Authors: WARREN JAY , MARTIN RICHARD O.
Published: July 2006

Reliable discrimination between sinus tachycardia (ST) and pathologic tachycardia has been a major problem for automatic implantable antitachycardia devices. In patients whose sinus response to activity is as rapid or faster than their pathologic tachycardia (rate crossover), these unsophisticated devices deliver the programmed tachycardia response to either the pathologic or sinus tachycardia. Over a one‐year period, 50 Intermedics Intertach Model 262–12 antitachycardia pulse generators were implanted to evaluate the specificity of a new group of tachycardia recognition algorithms. Patients were subjected to exercise testing and noninvasive programmed stimulation to demonstrate the efficacy of this new approach. The five recognition algorithms tested were various combinations of the following criteria: high rate HR), sudden onset (SO), rate stability (RS), and sustained high rate (SHR). False positive rates (tachycardia response inappropriately triggered by ST) were as follows: HR (93%); HR + SO (3%); HR + RS (63%); HR + (RS or SHR) (87%); HR + HS + SO (8%). Pair‐wise significance testing between HR only and HR + SO (p < 0.001), HR + RS (p = 0.01) and HR + SO + RS (p < 0.001), demonstrated a significant reduction in the rate of false positives through the use of the sudden onset and rate stability criteria in concert with the standard high rate criterion.
Detection of Ventricular Tachycardia and Fibrillation Using ECG Processing and Intramyocardial Pressure Gradients
Authors: AUBERT ANDRÉ E. , DENYS BART G. , ECTOR HUGO , DE GEEST H.
Published: July 2006

The automatic termination of malignant tachyarrhythmias and of ventricular fibrillation by an implantable device requires a reliable sensing of these episodes of abnormal ECG. Therefore, we induced tachyarrhythmias and fibrillation in eleven dogs and recorded electrograms and intramyocardial pressure. The electrograms were analyzed using the autocorrelation function and the probability density function. Intramyocardial pressure was monitored as a hemodynamic parameter. Results show that in the case of sinus rhythm, all methods are reliable, but in the case of VT and VF, electrogram processing only is insuffcient. It is concluded that combined monitoring of ECG processing and a hemodynamic parameter may increase the sensitivity of an automatic tachycardia‐fibrillation detection system.
A New Advancement in Noninvasive Electrophysiology: A Standard Laboratory Stimulator Pulse Coupled with an Implanted Pacemaker
Authors: WISH MARC , FLETCHER ROSS D. , COHEN ANDREW I. , SHOLDER JASON , KEEFE JAMES , MILLER FREDERICK
Published: July 2006

A new device for coupling the pulse from a standard laboratory stimulator to commercially available implanted pacemakers for use in noninvasive electrophysiology testing has been developed. When programmed to an electrophysiology mode, a 37 kHz carrier wave, generated by the programmer, maintains communication with the implanted pacemaker. Stimuli generated from a standard lab stimulator cause a break in the carrier wave and an output from the pacemaker. Cycle lengths as short as 127 msec can be attained. In addition to standard electrophysiology testing, this noninvasive electrophysiological technique can be used to fibrillate the heart to test the efficacy of automatic implantable cardioverter/defibrillators.
The Natural History of Sick Sinus Syndrome
Authors: SUTTON RICHARD , KENNY ROSE‐ANNE
Published: July 2006

A literature review has addressed the two major factors in disease progression in sick sinus syndrome: atrioventricular block and atrial fibrillation. An incidence of atrioventricular block of 8.4 percent in a follow‐up period of 34.2 months is considered clinically significant and sufficient to justify use of a ventricular lead in pacemaker management. Atrial fibrillation occurs much more commonly [22.3%] in ventricular pacing than with atrial demand pacing (3.9%) in a 21/2 year observation period. Coincident with the reduction in arrhythmia achieved by atrial demand pacing is a significant reduction in systemic embolism (1.6% vs. 13%]. This is considered largely to be due to the improved rhythm control with AAI pacing but also possibly to the avoidance of retrograde atrioventricular conduction. The benefits of AAI pacing in terms of mortality in sick sinus syndrome have not yet been fully assessed. In the future, DDI pacing is recommended with, in some patients, the addition of another sensor to provide rate responsiveness on exercise.
The Future of Single Chamber Pacing
Authors: RYDÉN LARS
Published: July 2006

Although dual chamber pacemakers have held much interest in pacing over the past several years, single chamber pacing remains the modality of choice, worldwide, in the greatest proportion of patients. Atrial or ventricular demand pacing is safe and effective in the majority of patients. In addition, sensors may be used to increase ventricular pacing rate in order to improve cardiac performance.
Advances in Single‐Chamber Pacemaker Diagnostic Data
Authors: ADLER STEVE , WHISTLER STEVE , MARTIN RICHARD
Published: July 2006

Diagnostic data, which is Holter‐type information documenting the pulse generators' interaction with the patient over time, are now available in single chamber pulse generators from at least six manufacturers. Diagnostic data are available in bradycardia, tachycardia, and rate‐responsive pulse generators. Six hypothetical examples discuss the clinical utility of advanced diagnostic data. Three examples examine the use of diagnostic data with bradycardia pulse generators. These use rate histograms or high‐rate counters to solve programming and patient problems. Two examples involve antitachycardia pulse generators and the uses/or diagnostic data in both chronic and acute cases. One example deals with the use of maximum and minimum temperature diagnostics in proper programming of a temperature rate‐responsive device.
Chronic Antithrombogenic Biomaterials Screen
Authors: LUBIN MARK , NAPPHOLZ TIBOR , MILLER C. W. , WRIGLEY R. , CLUBB FRED
Published: July 2006

The widespread usage of chronic implantable sensors in cardiac device systems has been hampered by both sensor technology issues and the lack of surface passivations with chronic antithrombogenic capabilities. In this study, dummy pacing leads with six types of passivations were implanted for 17 weeks in 36 dogs to assess thrombogenic character, degree of tissue growth and encapulation, and general performance in providing optically clear windows into the blood or body tissues. Asceptic surgical procedures were used and complete blood work‐up was performed every two weeks postop. Two dogs served as surgical shams to monitor system artifacts. At explant the devices fairly clearly divided themselves into two groups based on the percent of exposed surface area covered by gross macroscopic tissue accumulations. There were three passivated types in each group. Scanning election microscopy (SEM) and energy dispersive analysis of x‐rays (EDAX) techniques were used to investigate further the samples from the three passivation types that performed “better” based an percent surface area analysis. Issues that became prominent were substrate surface finish and topography, and some mineralization phenomena. Some of the evidence raises The possibility that processes that provide chronic antithrombogenic performance might also enhance mineralization or propensity toward natural breakdown processes. These questions are now being more closely addressed in follow‐up studies now in progress.
Ten‐Year Experience with Implanted Polyurethane Lead Insulation
Authors: STOKES KENNETH B. , CHURCH TIMOTHY
Published: July 2006

Polyurethane leads have been implanted in humans since 1977. Because of cases of stress cracking found in 1981, changes in the manufacturing process were made. Subsequent performance was excellent. There remains concern regarding the ability to predict accurately long‐term performance. However, the advent of reliable, statistically accurate actuarial data coupled with accelerated tests predictive of human performance has restored confidence in the newer polyurethane lead technology.
Long‐Term Performance of Polyurethane Pacing Leads: Mechanisms of Design‐Related Failures
Authors: PHILLIPS RICHARD , FREY MICHAEL , MARTIN RICHARD O.
Published: July 2006

Environmental stress cracking has been identified as a crack propagating mechanism in polyurethane‐insulated, heart pacemaker leads, which is directly related to specific lead design parameters. Lead designs imposing excessive stress on the polyurethane insulation through an interference fit between the coil and polymer have demonstrated insulation failures. Conversely, low‐stress designs have shown virtually no insulation problems. The higher‐stress designs have used organic solvents to facilitate coil placement during manufacturing. which may result in lowering the polymer's ability to resist the higher stress. In addition, a specific silver‐containing coil wire composition has been found to galvanically corrode upon body fluid intrusion info the lead, ionizing the silver. These ions interact with the polyurethane polymer resulting in the loss of polymer strength. All polyurethane lead failures to date have been specific to high stress and/or chemical interaction. Leads using low‐stress designs and nonreactive coil wire compositions continue to demonstrate a positive clinical experience.
A Voluntary Standard for 3.2 mm Unipolar and Bipolar Pacemaker Leads and Connectors
Authors: CALFEE RICHARD V. , SAULSON STANLEY H.
Published: July 2006

In response to concerns over proliferation of new and different technologies in leads and lead connectors, a voluntary standard for 3.2 mm unipolar and bipolar pacemaker leads and connectors has been established. One major difficulty overcome in the process was the design of the voluntary standard. The greatest controversy centers around the design for the sealing mechanism for the connection of the pacemaker to the leads. Some suggest that the sealing mechanism should be in the form of seal rings on the lead; others believe that it is preferable to have the seal rings inside the pacemaker cavity. The new voluntary standard finally agreed upon represents a compromise position. It is a standard that appeals to future development since it favors leads smaller than those in current distribution, and provides for backward compatibility with existing leads. In addition, it allows each manufacturer as much design flexibility as possible. It is hoped that this voluntary standard will be universally accepted throughout the industry.
Electrochemistry of After‐Pacing Potentials on Electrodes
Authors: THULL R. , SCHALDACH M.
Published: July 2006

Predictable electrochemical behavior of electrodes in physiologic pacemakers is desirable. The after‐pacing potentials play a major role in determining precise sensing and pacing performance between both chambers. Ideally, pacemaker input impedance should be high (in relation to the electrode/blood interface), whereas the potential remaining on the electrode should be as low as possible. Both of these conditions are influenced by the electrode material, structure, and design. Results of in vivo and in vitro testing show that the after‐pacing potential interference is directly related to the potential decay, and these values are in general considerably shorter than the blanking periods.
Sensing Properties of Pacemaker Leads
Authors: IRNICH WERNER
Published: July 2006

It is already general practice to attribute sensing properties to geometry and surface structure of pacemaker leads. We have to analyze critically whether claims of having found leads with high sensitivity are in accordance with experimental and theoretical findings. From a model can be derived what kind of typical signal structure will originate from an electrode when an excitation wave crosses it, and what of this signal is influenced by electrode parameters. With decreasing surface area, the frequency content of the signal, the impedance, and, theoretically, the amplitude, increases. If the pacemaker characteristics are not matched to the lead properties, this inverse relationship becomes a direct one: If the input impedance is too low or the upper cut‐off frequency of the bandpass is not high enough, the effective heart signal seems to be diminished with decreasing size. This, however, is more a pulse generator than a lead problem. If all pacers would possess an input impedance of ≥100 Kω and an upper cut‐off frequency of ≥350 Hz, an attenuation of the heart signal would be ≤10% and thus, the results with different leads would be very similar and of equally high sensitivity.
Target Lead—Low Threshold Electrode
Authors: DJORDJEVIC MILAN , STOJANOV PETAR , VELIMIROVIC DUSAN , KOCOVIC DUSAN
Published: July 2006

Acute and chronic threshold measurements were compared for three different electrodes: the Medtronic* Target Tip model 4011, the Medtronic Ring Tip Model 6971 and the Siemens‐Elema** Carbon Tip Model 412S. The results of this study show that acute thresholds are lower with the Target Tip lead as compared to the other two, This finding applies to chronic thresholds as well. The results of this study favor programming to lower output energies while maintaining adequate safety margins with this lead system.
Long‐Term Performance of Endocardial Leads with Steroid‐Eluting Electrodes
Authors: KRUSE IB. MUNKSGAARD
Published: July 2006

During a three‐year period, 48 steroid‐eluting leads (Medtronic* 4003 and 4503] have been implanted in 39 patients. 23 were implanted in the atrium and 25 in the ventricle. 36 patients with 45 leads have been observed for more than 12 months. Stimulation thresholds have been followed using pulse generators with variable output (vario): 12 atrial and 11 ventricular leads, 4 atrial leads and 11 ventricular leads have been followed using pulse generators with variable pulse‐width (auto‐threshold], P‐waves have been followed using telemetry or sensitivity programming (23 atrial leads). R‐waves have been followed using telemetry in 11 ventricular leads. Mean stimulation thresholds after 2 years are 0.7 V ± 0.2 in the atrium and 0.8 V ± 0.3 in the ventricle. P‐waves after 2 years are of magnitudes allowing a sensitivity setting of 2.5 mV in 12 cases and of 1.5 mV in 2 cases; R‐waves have in all cases been high enough to permit lowest programmable sensitivity setting. During the observation time, two patients have died from nonpacing‐related causes. The results obtained from this investigation document low stimulation thresholds and good sensing levels in both ventricle and atrium using the steroid‐eluting electrode with no significant changes after 6 weeks postimplant.
Electrochemical Properties of Platinum, Glassy Carbon, and Pyrographite as Stimulating Electrodes
Authors: MUND K. , RICHTER G. , WEIDLICH E. , FAHLSTRÖM U.
Published: July 2006

Presently, platinum, platinum‐iridium, and carbon (glossy and pyrographite) are the preferred materials to be used as stimulating electrodes. Electrochemical tests revealed higher thresholds with Pt‐Ir, which possibly are a result of excessive connective tissue growth. A porous structure appears to be preferred especially if the electrode materials are smooth and activated glassy carbon. When comparing power consumption, glassy carbon was found to be a superior electrode material.
Six Years' Experience with Atrial Leads
Authors: BROWNLEE W.C. , HIRST ROSELYN M.
Published: July 2006

This report describes a six‐year experience with atrial leads consisting of 329 unipolar and 12 bipolar leads implanted in 302 patients. A variety of lead types were used: passive fixation with preformed J [including tines or fins in a solid electrode]; porous tip electrodes with small tines, most of which were also preformed; active fixation leads (both straight and preformed); and finally bipolar leads, which were all preformed. No statistical differences were found between the P waves recorded from various unipolar leads. Similarly, there were no statistical differences found between voltage or energy thresholds between the different types of leads. The complication rate included 6.3% of early complications and 4.7% late complications for a total complication rate of 11%. This compares to a complication rate of 2% for ventricular leads. Thus, the complication rate of atrial leads is higher than ventricular leads; this must be considered when selecting a pacemaker system for a given patient.
Simplifying Pacemaker Follow‐up by the Implementation of the NASPE Standards on Computer Interface
Authors: BENEDEK Z. MICHAEL , FURMAN SEYMOUR
Published: July 2006

One of the basic limitations for the development and use of more sophisticated pacemakers is the difficulty to provide adequate instrumentation and methodology for the follow‐up in the clinical environment. To address this problem, the NASPE (North American Society of Pacing and Electrophysiology) Computer Committee has developed an interface standard to allow communication with the pacemaker programmer through many computer systems. The document recommends the use of the RS 232/c (CCITT V.24) interface with baud rates variable from 300 to 19,200, 7 bit word, no parity and Xon/Xoff protocol. The actual message format consists of an SOH code, a function code describing the action to he taken, a variable code defining the parameter on which the action is to be taken, and the actual numerical data. The CHECKSUM is calculated by summing all the ASCII codes beginning after the SOH code and ending with the last byte preceding the checksum itself. The last seven bits so calculated are attached to the message, and a consecutive ETX code ends the communication. At the receiving end, the checksum is recalculated and compared to the value received. If the two match, the message is accepted. Using this format, compatible computer software and pacemaker programmers can be developed independently and function as a unit. The protocol is capable of real‐time ECG transmission.
Twelve Years of Clinical Experience with Lithium Pulse Generators
Authors: HAUSER ROBERT G. , WIMER ELIZABETH A. , TIMMIS GERALD C. , GORDON SEYMOUR , STALLER BERNARD , KLODNYCKY MARY , EISENHAUER ANDREW , GOREN CAROLYN , MORAN JOHN F. , DAVIS ANDY A. , WALSH RONALD , MCDONOUGH TIMOTHY , LAWLESS CHRISTINE , WYNDHAM CHRISTOPHER
Published: July 2006

The clinical performance of 9,651 lithium pulse generators, which were implanted at our registry hospitals since 1973, was assessed by analysis of actuarial survival data and information obtained at the time of pacemaker failure. Cumulative survival estimates for all units were: 5 years, 94 percent, 7 years, 81 percent, 10 years, 62 percent. Discriminant actuarial analysis revealed no differences between lithium iodine and lithium cupric sulfide longevity. Battery depletion was found in 49.1 percent of 277 units subjected to detailed explant analysis, while 31 percent and 8.7 percent had component and hermetic seal defects, respectively. Of the pulse generators with battery depletion, ail but two units exhibited normal end‐of‐battery life behavior. We conclude that the lithium iodine and lithium cupric sulfide batteries are safe, long‐term energy sources; however, the impact of reduced battery size and dual chamber pacing on these performance parameters is unknown.
An Argument for Pacemaker Reuse: Pacemaker Mortality in 169 Patients over Ten Years
Authors: PRINGLE ROBERT A. , LEMAN ROBERT B. , KRATZ JOHN M. , GILLETTE PAUL C.
Published: July 2006

Retrospective examination of 169 consecutive pacemaker patient deaths was done to test the hypothesis that early mortality would preclude full utilization of current battery longevity. We found a 58% mortality within two years of the last generator implant. Nineteen percent occurred within six months, and 38% occurred within a year. This compares to a current clinic of 246 patients where 43% have utilized these pacemakers for greater than 48 months. The age comparison shows that those who died were older than the Jiving controls. The 58% 24‐month mortality demonstrates that many patients underutilize expected battery life. The economic implications o/pacemaker reuse can then be understood.
Antitachycardia Strategies
Authors: FISHER JOHN D. , MERCANDO ANTHONY M. , KIM SOO G.
Published: July 2006

The development of an antitachycardia strategy requires a cascade of assessments and decisions. The patient's problem and level of risk must be assessed in order to determine the goals of therapy. Empirical therapy is appropriate in low‐risk situations, and during that ultimate emergency, the treatment of cardiac arrest. Quantitative objective assessment of therapeutic efficacy is indicated in most other situations. Such assessments may be primarily passive, such as recording of drug blood levels or serial Holter monitoring; of provocative, as in serial electrophysiologic, exercise, or psychological stress testing. Selection of an antiarrhythmic modality requires a balance between the risk of therapy and the risks related to the arrhythmia. Any antitachycardia strategy must also consider relative costs, and regulatory and reimbursement policies.
Clinical Experience with a Software Based Tachycardia Reversion Pacemaker
Authors: NATHAN ANTHONY W. , CREAMER JOHN E. , DAVIES D. WYN , CAMM A. JOHN
Published: July 2006

Current generation antitachycardia pacemakers suffer from limitations concerning detection and distinction of pathological tachycardia and also from the termination modes available. To overcome many of these limitations, a new device (Intermedics Intertach 262–12) has been developed, and has now been implanted in nine patients, all of whom had failed drug treatment. Since implantation, all patients have complete control of their arrhythmias, and only one now requires drug therapy.
Safety and Efficacy of Pacing for Ventricular Tachycardia
Authors: HOLLEY L.K. , COOPER M. , UTHER J.B. , ROSS D.A.
Published: July 2006

This study was undertaken to determine the safety and efficacy of three different pacing modalities on the termination of ventricular tachyarrhythmias. Thirty‐two patients were studied in the electrophysiology laboratory. Three randomized pacing modalities were selected for attempted conversion: auto increment, auto burst, and random burst. In all three groups, arrhythmias with cycle lengths shorter than 230 ms required DC shock, with one exception. Those longer than 230 ms were terminated by pacing in 85% of cases. There was a 15% rate of acceleration. Thus, antitachycardia pacing for ventricular tachyarrhythmias should be considered only with defibrillating back‐up.
A Hierarchical Approach to the Treatment of Ventricular Tachycardias
Authors: HALUSKA EDWARD A. , WHISTLER STEPHEN J. , CALFEE RICHARD J.
Published: July 2006

Electrical management of ventricular tachycardias with an implanted device is greatly complicated by reduced hemodynamic tolerance to the tachycardia with increasing rate, and by the risk of accelerating the tachycardia into fibrillation. Pacing (extrastimuli, bursts), low‐energy cardioversion, and high‐energy defibrillation therapies are all useful in safely treating a ventricular tachycardia. A implantable device is described which allows the classification of up to four different arrhythmias each having their own detection criteria (including high rate, sudden onset, rate stability and sustained high rate). For each classified arrhythmia, up to four, therapies may be programmed to be sequentially delivered. This scheme allows for increasing on the aggressiveness of the therapy based on elapsed time, increased rate, or both; and provides a large amount of flexibility for tailoring the desired therapies to individual patients.
Implantable Pacers for Tachycardia Termination: Stimulation Techniques and Long‐Term Efficacy
Authors: FISHER JOHN D. , JOHNSTON DEBRA R. , KIM SOO G. , FURMAN SEYMOUR , MERCANDO ANTHONY M.
Published: July 2006

The long‐term efficacy of pacing for termination o/supraventricular tachycardia (SVT) and ventricular tachycardia (VT) was reviewed. Increasingly complex and sophisticated antitachycardia pacing stimulation patterns have evolved, and are outlined. Although excellent results are reported with simple patterns, it may be that the more complex algorithms increase the percentage o/tachycardia patients who may be candidates for implantation of a device. In the papers reviewed, there were 460 patients, 268 with SVT, and 192 with VT. Results were judged to be good‐excellent in 96.5% of both VT and SVT groups.
The Epidemiology of Tachyfibrillation in Sudden Death
Authors: GOLDSTEIN SIDNEY
Published: July 2006

Although death occurs suddenly in coronary heart disease, it is associated with a prior history o/cardiac disease in 85% and with prodromal symptoms in 73.8% of the patients resuscitated from cardiac arrest outside the hospital Sudden death was the first expression of coronary heart disease in 3.6% of the patient population. The fact that out‐of‐hospital sudden death is usually secondary to myocardial infarction and ischemia is supported by this clinical study and is suggested by other clinical and pathological studies of individuals dying suddenly.
Temporal Stability of Sequential Pulse Defibrillation Threshold
Authors: KALLOK MICHAEL J. , OLSON WALTER H. , MARCACCINI STEVEN J. , ALMQUIST CAROLYN K.
Published: July 2006

We have shown that sequential pulse defibrillation threshold voltage and total delivered energy do not change with maturation of the electrode tissue interface for up to 12 weeks after implantation of two different electrode configurations. This result is important to predict the future performance of an implantable defibrillator that is tested only at implant.
Effects of Physical Parameters of Fulguration on Electrophysiological and Anatomical Properties of Canine Myocardium
Authors: LAVERGNE TH. , LE HEUZEY J.Y. , BRUNEVAL P. , GUIZE L. , BOUTJDIR M. , VON EUW D. , PERONNEAU P.
Published: July 2006

In order lo determine the respective roles of catheter (Ct) physical properties and of energy levels in myocardial effects of fulguration, we delivered an electrical shock between the tip electrode of a Ct placed at the apex of the right ventricle and a large cutaneous cathodal electrode in 12 dogs. Two energy levels were used: Group A = 25 J (n = 6) and group B = 100 J (n = 6), and three Cts were studied. These Cts had different resistances (R) and active surface electrodes (S): Ct 1 (R = 0.3 ω S=12 mm2), Ct 2 (H = 0.3 ω, S = 2 mm2, Ct 3 (R = 2 ω S = 13 mm2). Complex ventricular arrhythmias were observed in 5/6 cases at 100J but only in 1/6 case at 25J and were independent of the Ct type. Following the shock, the effective ventricular refractory period (S1 S1= 300 msec) increased significantly only at 100J(11%, p = 0.03). Anatomical lesions were wider (10.6 vs. 5.2 mm, p < 0.05) and deeper (100 vs. 55%, p < 0.05) in the 100 J group. In contrast, there was no significant difference in the electrophysiological and anatomical changes between the three Cts. In conclusion, (1) arrhythmogenic adverse effects of ventricular Ct fulguration are related to the delivered energy; (2) on the contrary, they seem only slightly dependent on Ct physical properties at these energy levels; (3) a 2 J/kg shock is not only effective but also seems to be safe.
A New Low Energy Power Source for Catheter Ablation
Authors: CUNNINGHAM DAVID , ROWLAND EDWARD , RICKARDS ANTHONY F.
Published: July 2006

The current technology in the area of catheter ablation for cardiac arrhythmia is limited by the amount of damage sustained by the ablated area in relationship to the energy used. Thus, a newly designed power source is described in this report in three patients, two with resistant atrial flutter/fibrillation and one with a reentrant AV tachycardia. The delivered energy in ail patients was 5.3 joules or less with the exception of a single shock of 37.5 joules, which was required in one patient. We conclude that this effort of low energy ablation using a unique power source represents an advance in the field of ablation that merits further evaluation.