bluuebunny/crossref_metadata_2025 huggingface dataset:
Right Atrial‐ventricular Dissociation and Entrainment while Pacing from High Right Atrium and Coronary Sinus during Circus Movement Tachycardias
Authors: PORTILLO BOLIVAR , CASTELLANOS AGUSTIN , MEJIAS JOSE , ZAMAN LIAQAT , LEON‐PORTILLO NELLY , MYERBURG ROBERT J.
Published: July 2006

Thirteen patients with circus movement tachycardias [CMT] were studied. Twelve had left‐sided, and one, right‐sided, accessory pathways. Entrainment was possible during overdrive high right atrial stimulation in 13/13 patients, and during coronary sinus pacing in 10/12 patients. The minimal pacing rates required for this to occur were 10 to 31 beats/min faster than those of the tachycardias. Short episodes of right atrial‐ventricular dissociation occurred while pacing from the high right atrium [6/13 patients), but not from the coronary sinus (0/13 patients). It is possible to explain this phenomenon by postulating the existence of two distinct atrioventricular (AV) nodal inputs (one for right‐sided and the other for left‐sided impulses); it could also have been an expression of the close distance existing between the AV node and the coronary sinus. Entrainment, by defining a range of paring rates followed by resumption of the tachycardia upon the cessation of stimulation, indicated that faster rates were needed for the CMT to be interrupted. However, regardless of the pacing rate and pacing site, tachycardia termination occurred when an anterograde impulse was blocked at the. AV node. The information obtained from this study suggests that some patients with drug‐resistant CMT may benefit from pacing modes capable of terminating the arrhythmia “through entrainment” at the slowest atrial rate at which this is possible.
The Effects of Nuclear Magnetic Resonance Imagers on External and Implantable Pulse Generators
Authors: FETTER JOSEPH , ARAM GEORGE , HOLMES DAVID R. , GRAY JOEL E. , HAYES DAVID L.
Published: July 2006

This study evaluates the effect of nuclear magnetic resonance (NMR) scanning on pacemaker function. it must be emphasized that each manufacturer's pulse generators and each pacing modality may behave differently and, therefore, require individual evaluation. According to our results, patients with pacemakers should have their pacing activity monitored continuously during scanning with the NMR 1500 gauss imaging system. External pulse generators should he net to the asynchronous mode and placed outside the NMR image volume but within the radiofrequency [RF] shield. Implanted pacemakers should be verified for type and mode of operation. Ail implantable pulse generators evaluated reverted from the demand to the asynchronous mode within the magnetic field of the scanner. There was no observable damage to the discrete pacemaker components that were tested.

In vivo testing of implantable single‐chamber pulse generators did not significantly alter the pacemaker's operating parameters. Changes in stimulation rate analogous to the RF field pulse rate were seen. In single‐chamber devices the resultant rate was a multiple of the RF frequency, changing to a value less than the normal asynchronous magnetic rate. With morn sophisticated dual‐chamber devices the results varied. With VDD pacing during RF scanning, the cardiac stimulation rote increased to a value analogous to the value of the RF field modulation period.

More extensive in vivo testing using different models of pulse generators of various manufacturers is needed to identify specific device susceptibility to the RF, time variance and steady‐state magnet fields. From these data a comprehensive statement about NMR scanning of patients with implanted pacemakers can be made.
Optimal Pacemaker Sensing with Respect to Amplitude and Slew Rate of Intracardiac Electrograms: Theoretical Analysis by Computer Simulation
Authors: ARAI YUTAKA , YAMAZOE MASARU , TOEDA TETSURO , HOSHINO YUMIKO , SHIBATA AKIRA , MAKINO HIDEO , SAITOH YOSHIAKI
Published: July 2006

The optimal amplitude and slew rate of intracardiac electrograms for pacemaker sensing Here examined on a theoretical basis by computer simulation. The simulation was based on the concept that it is the voltage at the position of the pacing electrode in an electrical field of a moving electrical dipole. By changing the distance between the electrode and the myocardium and the moving velocity of the electrical dipole, simulated ECGs with arbitrary amplitudes and slew rates were generated by the computer and fed to a bandpass filter. This filter was equivalent to those assembled in some models of permanent pacemakers and had a center pass‐band frequency of 50 Hz and a Q of 1.0. The outputs of the filter were measured. The results showed that, for pacemaker sensing, simulated intracardiac electrograms with high amplitude should have high slew rates and those with low amplitudes should have low slew rates, although the absolute values depend on the characteristics of the bandpass filter and the sensing threshold of the pacemaker.
Recurrent Pulmonary Embolization Following Implantation of Transvenous Pacemaker
Authors: PASQUARIELLO JAMES L. , HARIMAN ROBERT J. , YUDELMAN IAN M. , FEIT ALAN , GOMES JOSEPH A.C. , EL‐SHERIF NABIL
Published: July 2006

A 44‐year‐old man developed recurrent pulmonary embolization after implantation of a permanent transvenous DVI pacemaker connected to polyurethane leads. Thrombus was found in the left innominate and subclavian veins around the pacemaker leads, but not in the right atrium or in the venous system of the pelvis and the lower extremities. The recurrence of pulmonary embolization followed discontinuation of treatment with Coumadin. This case demonstrates that lifelong anticoagulation is indicated in patients who have had pulmonary embolization and/or venous thrombosis around the pacemaker leads.
Precordial Pacing Windows
Authors: GEDDES L.A. , VOORHEES W.D. , BABBS C.F. , SISKEN R. , DeFORD J.
Published: July 2006

The threshold peak current for cardiac pacing with 10 ms rectangular pulses applied to precordial electrodes was determined in 18 anesthetized dogs (average weight 20.8 kg). The entire left and right precordium was mapped with a 1 cm diameter (cathode) electrode, paired with a 10 cm diameter reference electrode on the opposite chest. It was found that the lowest current required for pacing corresponded to the region of the apex beat on the left chest. At this site the average pacing threshold with the 1 cm electrode was 34.3 mA (peak). No sharply defined low pacing current area was found on the right chest, indicating that the location for the right chest electrode is not critical. The term “pacing window” is introduced to identify the region on the precordium where the pacing threshold is lowest. Studies were also performed to determine the manner in which the pacing current increased as electrode diameter was increased beyond the diameter of the pacing window. It was determined that little is to be gained with a left chest electrode larger than 5 cm in diameter in this animal study.
Demonstration of Reentry Within the Right Bundle Branch in Man
Authors: LITTMANN LÁSZLÓ , TENCZER JÓZSE F , SVENSON ROBERT H.
Published: July 2006

Reentry within the right bundle branch which, to our knowledge is a hitherto undescribed mechanism of His‐Purkinje reentry in man, was elicited during programmed right ventricular stimulation. Electrophysiologic analysis excluded atrioventricular nodal reentry. His bundle reentry, reentry involving both bundle branches, and intraventricular micro‐reentry.
A Case Report Demonstrating Spontaneous Change in Tachycardia Terminating Window
Authors: den DULK KAREL , BRUGADA PEDRO , WELLENS HEIN J.J.
Published: July 2006

A patient who received a patient‐activated pacemaker system for termination of paroxysmal, drug‐resistant, ventricular tachycardia is described. During the pre‐implant invasive electrophysiological (EP) study and the three post‐implant non‐invasive EP studies, tachycardias were easily and reproducibly terminated by two stimuli using the interval scanning mode. On the fourth day post‐implant, this pacing mode no longer terminated tachycardia at rest. A new pacing mode using more stimuli was then found to terminate the tachycardia reproducibly under various Physiological conditions. This case report demonstrates a spontaneous change in the tachycardia terminating window and the usefulness of versatility in antitachycardia pacemaker systems.
Development of a Coding System for Pacemakers
Authors: IRNICH WERNER
Published: July 2006

Since the establishment of the first pacemaker coding system (The Three‐Letter Code, 1974) with its nine different pacemaker modes, the number of available modes has increased remarkably. As a consequence, even the expanded “Five‐letter‐Code” is no longer adequate to describe the different modes with sufficient precision. To overcome these difficulties, we tried to construct a coding system that represents each mode in a pictorial form, which is simultaneously and precisely defined by a schematic circuit and a number within a numerical matrix.
Recurrent Ventricular Tachycardia Responsive to Verapamil
Authors: KLEIN GEORGE J. , MILLMAN PHILIP J. , YEE RAYMOND
Published: July 2006

We describe five young patients with recurrent ventricular tachycardia in the absence of organic heart disease. In all patients tachycardia could be terminated or prevented with verapamil. Tachycardia in four patients was very similar, with a QRS pattern of right bundle branch block and left axis deviation. Electrophysiology studies in two patients showed that VT was inducible in one patient (rapid atrial or ventricular pacing, ventricular extrastimuli) but not in the other. The clinical and electrocardiographic similarities in these patients suggest that their ventricular tachycardias may share a common pathophysiology and may be dependent on slow channel activity.
Reversible End‐of‐Life Indicator Leading to Erroneous Pacemaker Replacement‐Pitfalls of Telemetry
Authors: SCHEIBELHOFER W. , KALIMAN J. , MAYR H. , MÜLLER H. , LACZKOVICS A. , KAINDL F.
Published: July 2006

In several modern pacemakers, end‐of‐life (EOL) is indicated by a single‐step rate drop, which is initiated by a voltage‐sensitive electronic switch. This switch may also be activated by other causes, such as very short voltage drops, low temperatures, and electrocautery. We report a case in which a Cordis 233 F Sequicor II pulse generator was operating at 51.6 bpm in VOO mode at the time of implantation. As telemetry seemed to indicate that back‐up pacing (the EOL indicator in this model was “off”, it was erroneously assumed that the pacemaker was not working properly. The unit was replaced by another impulse generator. At laboratory testing, the pacemaker was within specifications, when back‐up pacing was separately programmed off. In conclusion, physicians should be aware of the new phenomenon of reversible EOL indicators, and that they may not rely on telemetry in this respect. Future pacemakers should incorporate a telemetry message which prevents similar misunderstandings.
A New Pacemaker for Monitoring Asystole and Prevention of Adams‐Stokes Syndrome and Sudden Cardiac Death
Authors: ARAI YUTAKA , SHIBATA AKIRA , KAZAMA KAZUYA , MAKINO HIDEO , SAITOH YOSHIAKI
Published: July 2006

Patients with suspected Adams‐Stokes syndrome are examined by Holter monitoring. During the monitoring, there is the danger of syncopes occurring and there are even reports of sudden cardiac death. We therefore developed a pacemaker for cardiac arrest monitoring and the prevention of Adams‐Stokes syndrome and sudden cardiac death, which has the following functions: (1) the longest escape interval of the pacemaker not exceeding the value at which syncope is induced is determined by the decline of the mean heart rate including the asystole to a certain threshold rate; (2) once the pacemaker escapes from the interval it continues pacing for a while at a physiological rate to allow recover from ischemias in organs or tissues; and (3) to prevent overdrive suppression to the heart, the pacing rate gradually declines and stops pacing until the next asystole. This pacemaker is useful not only in the diagnosis of Adams‐Stokes syndrome but also in pharmacological and pathophysiological studies and in determining when pacing should cease.
A Digital Timing and Display Unit for Intraoperative Mapping of Cardiac Arrhythmias
Authors: ROSENFELDT FRANKLIN L. , HARPER RICHARD W. , WALL RONALD E. , UTHER JOHN B. , HILDER ROWLEY , SHARDEY GILBERT C.
Published: July 2006

An inexpensive display and timing unit incorporating a multichannel signal delay has been developed for mapping the heart during electrophysiological surgery. It provides a continuous digital readout of the time relationships between 3 introcardiac electrograms and the surface electrocordiogram. The electrograms are displayed on a storage oscilloscope with an automatic erase facility. This unit is used to locate accessory atriventricular connections in the Wolff‐parkinson‐White syndrome, to map ventricular tachycardias and to locate the bundle of His. The design has been refined during 5 years of use in over 200 operative procedures.
Pacemaker‐mediated Tachycardias: A New Modality of Treatment
Authors: WEBER HELMUT , SCHMITZ LOTHAR , HELLBERG KLAUS
Published: July 2006

Three Patients with pacemaker interactive drug resistant tachycardia underwent invasive electrophysiological studies. In the first patient, the retrograde conduction of the artificial reciprocating tachycardia was provided by two right‐sided accessory pathways and the antegrade conduction by an atrial synchronous plus generator. In addition, AV nodal tachycardia occurred alternately. In the second patient with intermittent atrial flutter, the AV node and, coincidentally, an AV sequential pulse generator provided high‐rate antegrade conduction to the ventricles. In the third patient with surgical complete heart block, intermittent AV‐nodal tachycardia induced retrograde atrial activation while an atrial synchronous pacemaker provided the antegrade conduction. Electrode catheter exploration of the heart allowed localization and closed‐chest ablation of the accessory pathways or AV node by delivering two to seven 200‐Joule direct‐current shocks through the appropriate electrode of the exploring catheter, Thereby, pacemaker‐mediated arrhythmias could be controlled in these patients in the follow‐up of 6 to 8 months.
Interference in Pacemakers
Authors: IRNICH WERNER
Published: July 2006

We attempt here to outline the different sources of interference and the methods of interference detection and protection with their advantages and disadvantages. A proposal is made as to how a better interference suppression could be established. A comparison of 16 pacemakers from ten manufacturers tested with different interference sources revealed a great variety, which does not allow one to generalize the problem of interference. As an example, an electric steel furnace with its magnetic field is described and how its influence on pacemakers can be estimated. Rules are given as to how pacemaker patients may be treated by electrotherapy. A test procedure for characterizing the specific interference behavior is proposed.
The Effect of Cycle Length on the Atrial Refractory Period
Authors: DENES PABLO
Published: July 2006

L'effet de la longuer du cycle sur la période réfractaire de l'oreillette a été mesuré chez 34 patients. L'effet du changement brusque du cycle de stimulation sur la période réfractaire auriculaire a été mesuré par l'introduction d'un cycle test (CLT) après le huitieme cycle stimulé (CLp). Ce cycle test corréspondait à un intervalle soit de 100 ms plus long (CLT= CLp+ 100 ms), soit plus court (CLT= CLp ‐ 100 ms) que le cycle stimulé. Ces résultats confirment (1) que les périodes réfractaires auriculaires raccourcissent avec un court cycle pendant la stimulation constante; (2) que du changement brusque du cycle stimulé résulte un changement de la période réfractaire. Ce changement est dans la même direction, mais de plus faible amplitude que le changement secondaire à la stimulation constante; (3) qu'il n'y a pas de corrélation entre le temps de conduction intra‐auriculaire et période réfractaire.
Supernormality: Recent Developments
Authors: CHILDERS RORY W.
Published: July 2006

Le plus grand progrès dans l'étude de la conduction supernormale dérive de l'hypothèse suivante: les accumulations focales de potassium dans les cryptes “calmes” (invaginations du milieu extracellulaire des fibres de Purkinje) font baisser le seuil de stimulation en raison de l'effet précoce de l'hyperkaliémie, c'est‐à‐dire baisse du seuil et accélération de la conduction. Ces effets disparaissent rapidement en diastole puisque l'équilibre ionique a lieu; le seuil augmente et reprend sa valeur en fin de diastole. On ne sait pas connu si ce mécanisme est applicable à la conduction supernormale des fibres atriales spécialisées. En comparant les courbes de puissance‐durée de la conduction supernormal et de l'automaticité déclenchée, la chute du seuil pendant la montée du post‐potentiel tardif a lieu plus tard que la phase supernormale et est suivie par une hausse du seuil (sur la descente du post‐potentiel). La conduction supernormale en revanche ne montre pas ce changement biphasique de la courbe puissance‐durée.
The Potential Role of the Implantable Defibrillator in Malignant Ventricular Arrhythmias
Authors: COUMEL PHILIPPE , LECLERCQ JEAN‐FRANCOIS , SLAMA ROBERT
Published: July 2006

Une arrythmie maligne est celle qui menace la vie du patient sans pouvoir étre efficacement prévue, prévenue, ou traitée. Toute arrythmie répondant à cette définition est une indication à l'implantation d'un défibrillateur. La simplicité de ces propositions n'est qu'apparente, et recouvre le problème le plus difficile posé par les troubles du rythme cardiaque. La défibriJJation par voie transthoracique utilisée depuis vingt ans a été le moyen thérapeutique qui, directement ou surtout indirectement par le biais de l'éléctrophysiologie clinique, a apporté le plus de connaissances dans le domaine des arrythmies cardiaques. Directement ou indirectement, il en sera de mème à long terme pour la technique de défibriliation implantée. Mais les problèmes d'ordre technique, médical, et économique sont ici beaucoup plus complèxes et ne seront pas resolus dans un avenir proche.
Pacemaker‐Mediated Tachycardias: An Unresolved Problem
Authors: HARTHORNE J. WARREN , EISENHAUER ANDREW C. , STEINHAUS DAVID M.
Published: July 2006

L'apparition de la stimulation double chambre qui restaure le synchronisme AV et permet l'adaptation du rythme aux stress physiologiques a constitué un progrès majeur dans la stimulation à but thérapeutique. Une tachycardie éléctronique indésirable peut naitre lorsque la sonde auriculaire d'un stimulateur VDD ou DDD détecte une onde P rétrograde, une tachycardie atriale, la contraction du muscle pectoral ou une interférence éléctromagnetique de l'environnement. Le rythme de la tachycardie est alors fonction du rythme maximum de stimulation du pacemaker. Dans ces conditions (bien que rarement) chez les patients porteurs d'une maladie coronarienne, une ischémie myocardique menaçante peut survenir. Dans la plupart des cas l'incidence et le rythme des tachycardies electroniques peuvent étre minimisés par une programmation judicieuse.
Techniques for Improving Cardiac Performance with Implantable Devices
Authors: HAUSER ROBERT G.
Published: July 2006

Plusieurs techniques sont disponibles afin d'ameliorer la performance cardiaque des patients atteints de bradyarythmies. Les plus classiques sont la préservation du synchronisme AV et l'asservissement, où le rythme de stimulation varie en fonction du rythme auriculaire. De nouveaux pacemakers asservis utilisent d'autres capteurs biologiques tels que l'espace QT, la fréquence veniilatoire, I'aciivité, les gaz et le pH sanguins et la température. De nouveaux capteurs biologiques utiJisant des indices de pression et de volumes sont actuellement à l'essai et seront probablement bientôt disponibles. La diffusion de ces nouvelles techniques devra être precédée par une étude minutieuse du bénéfice, des risques mais aussi du coût.
Critical Analysis of Sensors for Physiological Responsive Pacing
Authors: GILLETTE PAUL
Published: July 2006

La stimulation physiologique asservie comporte l'application de capteurs pour mesurer des parametrès physioiogiques, qui ensuite fournissent un rhythme asservi. Nous faions l'analyse de six systèmes en comparant (1) la rapidité des réponses (2) Ja fiabilité des capteurs et (3) la spécificité de chaque système. Bien qui'il n'existe pas de solution idéale, et qu'il existe des points faibles dans chaque système, plusieurs capteurs paraissent meilleurs que d'autres. II leur reste àêtre mieux étudiés. De plus, les indications et les bénéfices pour les patients doivent être clarifyés.
Tachycardia Detection in Implantable Antitachycardia Devices
Authors: JENKINS JANICE , BUMP THOMAS , MUNKENBECK FRAN , BROWN JEFFREY , ARZBAECHER ROBERT
Published: July 2006

Nous avons développé un algorithme permettant l'identification des tachycardies par un microcomputer utilisable dans un pacemaker antitachycardie. Celui ci distingue les tachycardies auriculaires, ventriculaires et de réentrée du noeud AV et ne reconnait pas les tachycordies sinusales. De même a été developpé une nouvelle méthode permettant au pacemaker à l'aide d'un extrastimulus auriculaire de distinguer les tachycardies paroxystiques 1/1 des tachycardies sinusales. Celle ci est actuellement testée au laboratoire d'éIectro‐physiologie. Les résullats préliminaires indiquent que ces deux tachycardies peuvent être distinguées de façon fiable par un extrastimulus délivré avec un couplage correct dans l'oreiilette droite.
The Management of Paroxysmal Tachycardias Using the Cybertach‐60
Authors: GRIFFIN JERRY C. , SWEENEY MICHAEL
Published: July 2006

Le Cybertach‐60 est ün stimulateur bipolaire multiprogrammable conçu pour la détection et la terminaison automatique des tachycardies de réentée par une stimulation en rafales. Entre 8/79 et 3/84, 143 patients aux USA ont reçus ce Stimulateur: 91 pour tachycardie supraventriculaire et 52 pour tachycardie ventriculaires. 82% des patients avec tachycardie supraventriculaire survivent, la période de surveillance étant de 1,8 an en moyenne. Pour eux, le stimulateur représente le traitement principal de l'arrythmie. 58% des patients avec tachycardie ventriculaire survivent et utilisent le stimulateur pour l'interruption de la tachycardie. Pour eux, la période de surveillance est de 1,1 ans en moyenne. Dans ce dernier groupe, il y avait 18 morts, dont 14 documentées non‐subites, et 4 morts subites non‐documentées. Aucun des 14 décés documentés n'était düà une arythmie ni à la stimulation. Le Cybertach‐60 a donc fait la preuve de son éfficacité dans le traitement à long terme des patients ayant des arrythmies par réentrée, en particulier par tachycardie supraventriculaire.
Initial Experience with Symbios Model 7008 Pacemaker
Authors: ZIPES DOUGLAS P. , PRYSTOWSKY ERIC N. , MILES WILLIAM M. , HEGER JAMES J.
Published: July 2006

Le Symbios 7008 est capable de traiter les bradycardies et les tachycardies. Nous rapportons ici notre expérience initiale chez 21 patients chez qui ce boitier a été implanté. Tous présentaient des tachyarythmies supraventriculaires qui ont été arretées par stimulation auriculaire rapide (19 pts) ou séquentielle. Plus de la moitié des patients présentaient aussi des bradyarythmies nécessitant une stimulation et ont done ainsi bénéficié des deux fonctions du boitier. En l'état actuel des choses, l'expérience est favorable.
Clinical Results with the Tachylog Antitachycardia Pacemaker
Authors: SOWTON EDGAR
Published: July 2006

Le Tachylog est un pacemaker à fonctions multiples, implantable, doté de plusieurs systèmes antitachycardie dont une recherche “intelligente” qui n'est pas prédétermée. Vingt‐cinq patients ont reçu le stimulateur Tachylog en Angleterre depuis décembre 1982. Seize présentaient des tachycardies supraventriculaires à fréquence cardiaque moyenne = 220/mn, et 9 des tachycardies ventriculaires à fréquence supérieure à 180/mn. Quatre patients avec tachycardie ventricuiaire sont décédés de maladie coronarienne évoluée et deux patients porteurs d'un syndrome de WPW ont été opérés (section de la voie accessoire) en raison d'une fibrillation auriculaire à réponse très rapide a l'effort. Le contrôle clinique de l'arythmie a été obtenu chez les 19 patients restants. Quatre vingt pour cent de ceux présentant des tachycardies supraventriculaires et deux sur cinq présentant des TV n'ont plus nécessité de traitement médical. Les problèmes se sont limités à des difficultés de detection avec les premières unités.
Implantable Cardioverter‐Defibrillator: Patient Selection and Implantation Protocol
Authors: REID PHILIP R. , GRIFFITH LAWRENCE S.C. , MOWER MORTON M. , PLATIA EDWARD V. , WATKINS LEVI , JUANTEGUY JUAN , MIROWSKI M.
Published: July 2006

L'expérience acquise lors des essais cliniques avec le défibrillateur implantable souligne l'importance d'un bilan physiopathologique précis dans la période préopératoire. Cette évaluation demande une documentation précise de la tachyarrythmie ventriculaire, une évaluation de la possibilité d'autres interventions éventuelles aussi bien que la considération de l'intéraction entre stimulateurs et médicamments antiarrythmiques.
Clinical Performance of the Implantable Cardioverter‐Defibrillator
Authors: MIROWSKI M. , REID PHILIP R. , MOWER MORTON M. , WATKINS LEVI , PLATIA EDWARD V. , GRIFFITH LAWRENCE S.C. , GUARNIERI THOMAS , THOMAS ANDRA , JUANTEGUY JUAN M.
Published: July 2006

Le cardioverter‐défibrillateur automatique implantable a été implanté chez 276 patients porteurs de tachycardies malignes tenaces avec une survie jusqu’è 50 mois (moyenne = 9.75 mois). Les results de cet appareil sont encourageants. Les risques et les complications associées sont acceptables et ressemblent è ceux des pacemakers. L'accélération des tachycardies ventriculaires ou l'induction de fibrillation ventriculaire sont traitées par le recyclage de l'appareil. Le défibrillateur a réduit la mortalité de ces patients è 2% durant la première année.
Implantation of Automatic Cardioverter‐Defibrillators Via Median Sternotomy
Authors: BRODMAN RICHARD , FISHER JOHN D. , FURMAN SEYMOUR , JOHNSTON DEBRA R. , KIM SOO G. , MATOS JEFFREY A. , WASPE LAWRENCE E.
Published: July 2006

Nous avons implané 15 défibrillateurs automatiques (Model B) chez 10 patients. La voie chirurgicale préferée est la sternotomie médiane. Nous préferons utiliser une électrode “patch” sur l'oreillette droite, une électrode “patch” sur l'apex du ventricule gauche et deux épicardiques pour le recueil du potentiel bipolaire. Alternativement, les “patch” peuvent être placés sur les faces antérieure du ventricule droit el postérieure du ventricule gauche si les seuils sont favorables. La période de surveillance représente 109 patients‐mois et tous survivent. Les défibrillateurs ont choqué la tachycardie ventriculaire, flutter ventriculaire, et fibrillation ventriculaire. Des chocs ont été délivrés egalement pour tachycardie sinusale et pour la fibrillation auriculaire au dessus de la fréquence cible dans 3 cas. L'épuisement prématurée de la pile s'est produit dans 4 stimulateurs Model B, trois à 18 mois après implantation et parait être dûà un défaut de la pile originale. Les chocs pour tachycardie supraventriculaire resteront un problème jusqu'à ce que l'on obtienne une meilleure différentiacion entre tachycardies ventriculaires et tachycardies supraventriculaires. Le défibrillateur semble prévenir la mort subite suivant les tachyarythmies ventriculaires.
Epicardial Implantation of the Automatic Implantable Defibrillator by Left Subcostal Tboracotomy
Authors: LAWRIE GERALD M. , GRIFFIN JERRY C. , WYNDHAM CHRISTOPHER R.G.
Published: July 2006

Le défibrillateur automatique implantable est un net progrés en ce qui concerne la therapeutique de certains patients présentanfs des tachycardies et/ou fibrillations ventriculaires. La technique initiale nécessitait la pose de deux éléctrodes transveineuses et d'une épicardique par thoracotomie gauche. Nous avons développé avec succés une approche purement épicardique à l'aide d'une thoracotomie sous costale gauche. L'expérience passée de l'implantation des pacemakers épicardiques par cette voie suggérait que celle ci serait bonne pour l'implantation du défibrillateur automatique. Les résultats initiaux nous encouragent à poursuivre son utilisation.
Electronic Control of Ventricular Tachyarrhythmias: Overview and Future Directions
Authors: WINKLE ROGER A.
Published: July 2006

Bien que des téchniques de stimulation dans les tachycardies ventricuJaires aient 6t6 cpuronn6s de succés chez certains patients, leur utilisation courante n’était pas possible avant l'introduction du défibrillateur automatique implantable à haute energie (25j). Le défibrillateur implantable servira à la fois comme traitement principal et aussi comme traitement secondaire dans les tachycardies ventriculaires induites par la stimulation. La mortalité des malades atteints de fibrillation et tachycardie ventriculaires devrait diminuer considérablement.
Interpretation of Dual Chamber Pacemaker Electrocardiograms
Authors: SUTTON R. , PERRINS E.J. , DUFFIN E.
Published: July 2006

A diagramming system has been developed to assist in interpreting dual chamber pacemaker electrocardiograms, The system is based on the ladder diagram principle but uses two separate ladders, one for the ECG allowing proper representation of atrial A‐V and ventricular activation, and a second ladder diagram below it for pacemaker events. The system is applicahle lo all current single ond dual chamber pacing modes and is easy to draw. The ladder diagram allows the logical sequence of timing events to be easily illustrated, and pocemtiker malfunction becomes clearly recognizable as a conflict between the ECG events ladder and the pacemaker timing ladder. The system is easy to apply and may eventually prove suitable for automatic generation by computer utilizing sophisticated pacemaker telemetry.
Effect of Enflurane, Isoflurane, and Halothane on Pacing Stimulation Thresholds in Man
Authors: ZAIDAN JAMES R. , CURLING PATRICK E. , CRAVER JOSEPH M.
Published: July 2006

Volatile anesthetic agents are often used in patients who require temporary epicardial pacing after cardiopulmonary bypass (CPB). However, the effect of anesthetic agents on energy stimulation thresholds is unknown. After CPB, 24 patients under diazepam‐narcotic‐pancuronium anesthesia ventilated with an FIO2=1.0 received equipotent concentrations of either enflurane, isoflurane, or halothane. Using temporary epicardial electrodes, energy stimulation thresholds were calculated using the data derived from a pacing systems analyzer. Volatile anesthetics do not change energy stimulation thresholds from those already present under diazepam‐narcotic‐pancuronium anesthesia.
Acute and Long‐Term Atrial and Ventricular Stimulation Thresholds with a Steroid‐Eluting Electrode
Authors: KRUSE IB MUNKSGAARD , TERPSTRA BEN
Published: July 2006

Thirty leads with a steroid‐eluting electrode (Medtronic 4003 and 4503) have been implanted in 24 patients, 11 in the atrium and 19 in the ventricle. Six patients received the steroid lead in both atrium and ventricle. The stimulation thresholds were followed using Elema pulse generators with Vario function in 15 patients (11 atrial leads and 10 ventricular leads) during 11 ± 3 months (mean ± SD). At 0.5 ms pulse duration the mean atrial and ventricular thresholds were 0.55 Volt ± 0.22 and 0.39 Volt ± 0.22 respectively at implant, 0.94 Volt ± 0.13 and 0.82 Volt ± 0.16 after 12 months. During the entire follow‐up period both atrial and ventricular mean thresholds never exceeded 1 V.
Activity‐Sensing, Rate‐Responsive Pacing: Improvement in Myocardial Performance with Exercise
Authors: HUMEN DENNIS P. , KOSTUK WILLIAM J. , KLEIN GEORGE J.
Published: July 2006

A sensor that detects body activity by low frequency sonic impulses has been incorporated in a pacemaker so that body activity may be translated to an increased pacing rate in response to exercise. The pacemaker is designed for patients who may benefit from an increased cardiac output mediated by an increased heart rate during exercise. Following permanent pacemaker implantation, six patients (mean age 69 years) entered a single blind, randomized, crossover trial for comparison of activity‐sensing, rate‐responsive pacing (A) to fixed rate demand pacing (D). Ventricular function was assessed by gated radionuclide ventriculography at rest and at exercise, while exercise capacity was assessed by treadmill performance, along with measurements of oxygen consumption and carbon dioxide production. Total treadmill duration and maximum oxygen consumption were similar in the two pacing modes (A = 284 ± 244 s, 13.4 ± 3.4 ml O2/min/kg; D = 256 ± 250 s, 11.7 ± 3.7 ml O2/min/kg). Anaerobic threshold, however, was significantly improved (A = 266 ± 199 s, (p<.05), 13.0 ± 2.2 ml O2/min/kg (p < .01); D = 231 ± 208 s, 10.8 ± 2.3 ml O2/min/kg). This improvement was associated with an enhanced exercise cardiac output (A = 4.51 ± 1.3 L/min/m2; D = 3.61 ± .84 L/min/m2; p < .05) which was mediated by an increased heart rate (A = 95 ± 12 bpm; D = 68 ± 2 bpm; p < .01), maintenance of stroke volume (A = 47 ± 10 ml/m2; D = 54 ± 14 ml/m2) and absence of cardiac dilatation (EDVI A = 109 ± 25 ml/m2; D = 120 ± 32 ml/m2). Holter monitoring revealed rare instances of unexpected heart rate increases secondary to external activation of the sensor with no significant adverse effects being encountered. We conclude that activity‐sensing, rate‐responsive pacing offers the potential for increased exercise tolerance secondary to improved cardiac function.
Multiple Accessory Pathways: A Combined Electrophysiological and Radionuclide Study
Authors: RAKOVEC PETER , KRANJEC IGOR , FETTICH JURIJ J. , POHAR BOJAN , FIDLER VALENTIN
Published: July 2006

Electrophysiological study in a patient with Wolff‐Parkinson‐White syndrome revealed multiple accessory pathways: Kent bundle and Mahaim nodoventricular and fasciculoventricular fibers. Radionuclide phase imaging disclosed two distinct ventricular activation sequences during sinus rhythm or slow atrial pacing and during fast atrial pacing. The third activation pattern could be recorded after injection of ajmaline, which abolished signs of preexcitation in the electrocardiogram. Phase image in combination with pacing and pharmacological interventions can, at least in some cases, detect complex preexcitation syndromes noninvasively.
Measurement of Pacing Threshold
Authors: ECTOR H. , WITTERS E. , TANGHE L. , AUBERT A. , De GEEST H.
Published: July 2006

Thresholds in constant currenl und constant voltagte are reported for 405 CPI 4118 (Cardiac Pacemakers, Inc.) tined leads. In 98% of the cases, the constant current threshold was equal to or lower than 0.6 mA. A constant voltage threshold was equal to or lower than 0.5 V in 96% of the cases. Three external pacemakers and two pacing system analyzers were evaluated as threshold testing devices. For analyzing the waveforms of current and voltage stimuli, a calibrated isolation amplifier was used. We could not find a definite difference between the value, at which pacing is lost with reduction of the pulse generator output, and the value at which increase reestablishes pacing.
Use of Atrial Pacing in a Young Population
Authors: GILLETTE PAUL C. , WAMPLER DEBORAH G. , SHANNON CATHLEEN , OTT DAVID
Published: July 2006

Forty pediatric and young aduit patients (1–20 years; mean, 11 years of age) had implanlation of atrial demand (AAI) pacemakers over a 5.5 year period. Nineteen were impllinted by epicardial technique and 21 transvcnously. Standard lithium single chamber pulse generators and standard atriai leads were used. Operative stimulation thresholds were better for transivenous leads than for epicardial (0.75 volts vs. 1.5 volls at 0.5 ms) (p < 0.05). Pulse width thresholds at a mean of 1.5 years were not significantly different (0.11 ms for transvenous vs. 0.1 8 for epicardial). No patient developed AV block. Eight patients (four epicardial and four endocardial) required reoperation during the mean 3.5 year follow‐up—four because of lead problems and four because of persistent tachycardia. Of the six patients who received an automatic antitachycardia pacemaker, only one had persistent symptoms while seven of eight who received a standard unit continued to have symptoms. Twenty‐eight of 29 symptomatic patients without tachycardia became asymptomatic. Atrial pacing appears to be a safe and effective therapy for children with sick sinus syndrome.
Role of Invasive Electrophysiologic Studies in the Evaluation and Treatment of Supraventricular Tachycardia
Authors: DIMARCO JOHN P. , LERMAN BRUCE B.
Published: July 2006

Electrophysiologic studies have provided new insights into the mechanisms responsible for supraventricular arrhythmias and have enabled investigators to evaluate with precision the acute effects of pharmacologic, physiologic, electrical, and surgical interventions. Not all patients with supraventricular arrhyihmias require invasive studies, however, since empiric drug trials will often be adequate for management. At present, the clinical indications for study include the following: (1) for diagnosis of tachycardia mechanism when scalar ECG analysis is uncertain; (2) for assessment of risk of future life‐threatening arrhythmia; and (3) as a rapid means of assessing future therapy when sporadic arrhythmias are likely to be poorly tolerated. Innovations that include surgical and catheter ablations of tachycardia pathways and antitachycardia pacing devices hold great promise and in the future, will provide nonpharmacologic options for patients poorly controlled by or intolerant of drug therapy.
A Comparison between Conventional and Basket Transvenous Electrodes
Authors: LAGERGREN HANS
Published: July 2006

Three transvenous electrodes, two of a conventional type and one in the shape of a wire basket, were compared. In order to make a valid comparison, the electrodes ivere all attached to the same kind of lead. The conventional large and small surface electrodes showed no difference in early complication rate. The wire basket electrode, however, had significantly fewer early complications than the others. This was true whether the patients underwent a two‐ or a one‐step procedure, and whether the surgery was done by experienced or inexperienced pacemaker surgeons. When inserted by experienced surgeons in a one‐step procedure, the wire basket electrodes had an early complication rate of only 1.2%. Since this unrefined electrode that allows tissue ingrowth for improved anchoring has shown such good results, it is likely that other electrodes that have heen perfected, of a hollow or porous design, will also he advantageous to the patients and show good results.
Bipolar Tined Polyurethane Ventricular Lead: A Four‐Year Experience
Authors: HAYES DAVID L. , HOLMES DAVID R. , MERIDETH JOHN , OSBORN MICHAEL J. , VLIETSTRA RONALD E. , NEUBAUER SHARON A.
Published: July 2006

With the advent of polyurethane as an insulating material for permanent pacemaker leads, concern has arisen over the integrity and long‐term durability of poIyurethane‐insuJated pacing leads. Specific concern has arisen over particular bipolar tined polyurelhane ventricular leads. We have assessed our 4‐year experience with this lead. This experience involves two groups of patients, those with leads manufactured before a certain date and those with leads manufactured al a later date. In the first group (judged to be at increased risk) the failure rate was 8.8%, and in the second group (judged no(to be at increased risk] the rate was 3.9%. Lead failure occurred at an average af 17.5 months in the first group. Adequate follow‐up on the second group is not available to determine whether or not the failure rate may eventually be as high as thai in the early group, Actuarial analysis suggests that survivorship free of lead failure is probably not significantly different in the two groups. This experience points out the need for determining lead failure rates, identifying optimal lead design and configuration, and establishing a lead registry or mechanism by which the integrity of various pacing leads can be evaluated.
Externally Activated Antitachycardia Pacemaker With Noninvasive Electrophysiologic Re‐testing Capability
Authors: AONUMA KAZUTAKA , ROZANSKI JOHN J. , BAROLD S. SERGE , DEWITT PAUL L. , GOSSELIN ARTHUR J. , LISTER JOHN W.
Published: July 2006

An Omni Orlhocur 234A special device pacemaker was implanled in nine patients for treatment of drug‐resistant supraventricular tachycardia (three patients) or ventricular tachy cardia (six patients). This device is activated using a special external unit, which delivers from six to 15 stimuli at preselected coupling intervals ranging from 195 to 500 ms. Serial noninvasive electrophysiology studies were performed either in the hospital or on an outpatient basis using the triggered mode, which can respond fo programmed chest wall stimulation. Three patients with reciprocating supraventricular tachycardia were treated eJJectively by this device during an average follow‐up of 2.2 years. Of the six patients with stable ventricular tachycardia amenable to pacemaker termination, only four remained successful during an average follow‐up of 1.9 years. Such devices may find impor tant use in serial noninvasive electrophysiologic testing during long‐term clinical follow‐up. The pres ent form of this device is inadequate for widespread application, but may be useful for highly selected individuals.
Extraction of a Chronically Infected Endocardial Screw‐in Pacemaker Lead by Pigtail Catheter and Wire Loop Via the Femoral Vein
Authors: MAISCH BERNHARD , ERTL GEORG , KULKE HANS
Published: July 2006

A 71‐year‐old woman was admitted after partial removal of an infected pacemaker system. Septicemia and subcJavian vein thromhosis were present. With com bined use of a pigtail catheter and a wire loop originally developed for endoscopic polypedomy, the infected catheter was pulled into the inferior vena cava. Counterclockwise rotation of the pigtail catheter following its fixation to the electrode by the wire loop ailowed removal of the tip of the endocardial screw‐in electrode from the myocardium and its extraction. Open heart surgery was avoided and the source of chronic infection was removed.
Unusual Mechanism of PR Interval Variation and Nonreentrant Supraventricular Tachycardia as Manifestation of Simultaneous Anterograde Fast and Slow Conduction Through Dual Atrioventricular Nodal Pathways
Authors: BUSS JAN , KRAATZ JOCHEN , STEGARU BEATRICE , NEUSS HELMUT , HEENE DIETER L.
Published: July 2006

Noninvasive recordings in a 69‐year‐oId woman showed t wo distincl PR in tervals of about 0.21 and 0.58 s, suggestive of dual AV nodal conduction. Various unusual mechanisms of transition from short to long and from long to short conduclion interrals and phenomena of concealed conduction were due to the presence of two functionally separated intranodul pathways. Refractoriness of the slow pathway was associated with bradycardia. Episodes of tachycardia exhibiled a one‐to‐two relationship between P‐waves and ventricular activalions as a consequence of simultaneous anterograde fast and slow conduction leading to double ventricular responses lo single P‐waves.
Comparison of Vitreous Carbon and Elgiloy Transvenous Ventricular Pacing Leads
Authors: MOLAJO ADENIYI O. , BOWES ROBERT J. , FANANAPAZIR LAMEH , SLAVEN YVONNE , WILKINSON KERRY , BLANE JULIE , BENNETT DAVID H.
Published: July 2006

In a randomized prospective study of 150 patients. we compared two porous‐tipped, finned leads, one with a vitreous carbon lip (surface area = 12 mm2) and the other with an Elgiloy tip (surface area = 8 mm2). We assessed the acute and chronic stimulation thresholds and the ease of implantation of the two leads. The acute current thresholds for the vitreous carbon and Elgiloy‐tipped leads were 1.7 ± 0.5 (±SD) mA vs. 1.1 ± 0.4 mA (0.25 ms pulse width), 1.3 ± 0.5 mA vs. 0.9 ± 0.3 mA [0.5 ms], and 1.0 ± 0.3 mA vs. 0.8 ± 0.3 mA (0.75 ms), respectively (P < 0.0005). Impedance at implantation was 473 ± 121 ohms and 716 ± 285 ohms (P < 0.0005) for the carbon‐tipped and Elgiloy‐tipped leads, respectively. The R‐wave amplitudes were 10.2 ± 5.1 volts and 6.8 ± 3.0 volts, respectively (P < 0.0005). Both leads were easy to implant and showed low stable chronic thresholds from 3 weeks after implantation, at which time the stimulation threshold was 1.9 ± 1.0 volts vs. 1.5 ± 0.6 volts with the implonted voltage‐variable generators and 1.8 ± 0.8 mA vs. 1.6 ± 0.6 mA with the implanted current‐variable generators. Reoper‐ationfor displacement was required for two of the 87 (2.3%) carbon‐tipped and 2 of the 67 (3.2%) Elgiloy‐tipped leads. There was no exit block nor any other lead‐related complication. We conclude that both leads have similar and satisfactory performance.
Rate‐Responsive Pacing: Clinical Experience
Authors: DE ORO ANTONIO GOICOLEA , AYZA MIGUEL WILHELMI , DE LA LLANA RAMIKO , MORALES JOAQUÍN ALVAREZ , DÍEZ JOSÉ RAMÓN GUTIÉRREZ , ALVAREZ JUSTO GONZÁLEZ
Published: July 2006

Single chamber, rate‐responsive pacing is emerging as a new modality in cardiac pacing and in ihe near future, dual chamber rule‐responsive pacing may be the optimal solution for most pacemaker patients. In this report we describe our short‐ and long‐term clinical experience with two different rate‐responsive pacemakers: the RS4, an asynchronous atrial sensing ventricular pacemaker, and the TX‐pacemaker, which senses the evoked QT after a ventricular paced beat, as an indicator of metoholic demand. Both systems use a single ventricular lead. Nine palients received RS4 and 10 palients received TX units. All of these patients had AV block and good ventricular function except for three patients with sinas node disease in the TX group. Between 1 and 3 months after implantation, a 24‐hour Holter monitoring was performed, durifig which two maximal symptom‐limited treadmill exercise tests (Bruce protocol) were conducted in VVI (70 bpm) and rate‐responsive modes, in a random fashion. The mean follow‐up was 25 months in RS4 group and 10 months in TX group. Significant improvements in patient exercise tolerance were found in the rate‐responsive mode (9.0 vs. 6.6 METs in VVI) with similar results in both groups (RS4 and TX) despite higher ventricular pacing rates in the TX group (721 bpm vs. 102 bpm in RS4). An autolimited rate‐responsive pacemaker‐mediated tachycardia, induced by retrograde ventriculoatrial conduction, was observed in a patient with an RS4. There are still many problems with these units; at the end of follow‐up, only 4 out of 9 with the RS4 unit and 9 out of 10 with the TX unit have pacers that are functioning properly. Single chamber rate‐responsive pacing should be considered as a step forward in cardiac pacing.
Amplitude of Atrial Electrical Activity During Sinus Rhythm and During Atrial Flutter‐Fibrillation
Authors: KERR CHARLES R. , MASON MARCIA A.
Published: July 2006

The onset of atrial flutter or fibrillation in a patient with a DDD pacemaker may result in sensing of the atrial arrhythmia and an inappropriate ventricular pacing response. In order to assess the potential of this problem, we evaluated the amplitude of atrial electrograms recorded from the right atrial appendage during sinus rhythm and during atrial flutter or fibrillation during 19 episodes in 18 patients. in 11 episodes of fibrillation and eight episodes of flutter, there was no difference in amplitude of either unipolar or bipolar atrial electrograms compared to that recorded during sinus rhythm (p > 0.05). In 14 of 19 episodes, the direction of depolarization of the bipolar electrogram did not change appreciably between sinus rhythm and the atrial arrhythmia. In summary, there is insufficient difference between amplitude of atrial depolarizations recorded during sinus rhythm and atrial flutter or fibrillation to be differentiated reliably by DDD pacemakers.