bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Cardiac Electrophysiologic Studies in Patients with Unexplained Recurrent Syncope
Authors: AKHTAR MASOOD , SHENASA MOHAMMAD , DENKER STEPHEN , GILBERT CAROL J. , RIZWI NASIR
Published: July 2006

Cardiac electrophysiologic studies (EPS) with programmed electrical stimulation (PES) were performed in 30 patients with recurrent syncope to uncover possible arrhythmic etiology. All patients had undergone thorough medical and neurologic evaluation prior to EPS without finding a definitive cause for syncope. In the majority of patients an arrhythmic etiology for syncope was suspected but could not be documented utilizing the 12‐lead surface ECG, extended in‐hospital and/or ambulatory monitoring (for ≥ 48 hours) and exercise testing prior to the EPS. The studies provided a clue to the possible underlying rhythm disturbance which could have caused syncope in 16/30 patients. Sustained or nonsustained ventricular tachycardia and/or ventricular fibrillation was induced in 11/30, sinus node dysfunction in 4/30 and intra‐His block in the remaining one. Fourteen of the 16 have remained free of symptoms following therapy based on results of EPS during a follow‐up period ranging from 6–30 months (mean 16.5 ± 7.8). In 2/16 syncope recurred (one arrhythmic and one non‐arrhythmic) despite pacemaker therapy for sinus node dysfunction detected during EPS. In the remaining 14/30 patients, EPS and PES did not induce arrhythmia which could account for patient symptomatology and therefore no specific therapy could be recommended. Eleven of these 14 patients experienced a recurrence of symptoms within a 6–25 month period (mean 16.2 ± 6.8). Of the 16 patients with inducible arrhythmias considered clinically significant, 15 had associated structural heart disease. On the other hand, of the 14 patients without clinically significant arrhythmias, structural heart disease could be detected in only three. It is concluded that cardiac arrhythmias constitute a common cause of unexplained syncope, particularly in patients with structural heart disease, and that EPS with PES can uncover the type of arrhythmic disturbance in a significant number of cases.
Comparison of Resting Hemodynamic Indices and Exercise Performance During Atrial Synchronized and Asynchronous Ventricular Pacing
Authors: FANANAPAZIR LAMEH , SRINIVAS VENKATESWARAN , BENNETT DAVID H.
Published: July 2006

Resting hemodynamic indices and exercise tolerance were measured during atrial synchronized (VAT) and asynchronous ventricular pacing (VOO) in 35 patients with implanted pacemakers which could be externally programmed to function in either pacing mode. Cardiac output and mean systemic arterial pressure were significantly greater during VAT pacing (VAT: 4.5 ± 1.21 /min, 115 ± 28 mmHg; VOO: 3.7 ± 0.8 1/min 105 ± 25 mmHg respectively), although there was no difference in pulmonary artery end‐diastolic pressure. Maximal exercise performance was assessed using the Bruce protocol in both pacing modes. Neither the patient nor the supervising physician was aware of the preselected pacing mode; a second physician monitored the electrocardiogram and blood pressure but influenced the point of exercise termination only if a potentially dangerous arrhythmia or hypotension occured. Blood pressure responses were superior and atrial rates lower during VAT pacing, In all but five patients, exercise tolerance was improved by VAT pacing. This amounted to 33 percent or more in 23/35 patients. This improvement was shown to be maintained in the 20 patients who had repeat exercise tests several weeks later. Ventricular arrhythmias, hypotension, and lightheadedness frequently complicated exercise during asynchronous pacing but occurred rarely with atrial synchronized pacing. Resting hemodynamic indices did not predict the extent of improvement gained by physiological pacing.
Clinical Evaluation of a Single‐Pass Implantable Electrode for All Modes of Pacing. The “Crown of Thorns” Lead
Authors: WAINWRIGHT RAY , CRICK JONATHAN , SOWTON EDGAR
Published: July 2006

Physiological pacing was instituted in 37 patients (33 men and 6 women), mean age 67 years (range 33–77 years), using a variety of multiprogram‐mable generators attached to a permanent single‐pass dual chamber electrode. Eleven patients were paced in VAT mode (Cordis 208A or Siemens‐Elema 625 generator), two patients in DVI mode (Inter‐medics Cyberlith IV generator) and four patients in DDD mode (Siemens‐Elema 664/P33 or Telec‐tronics Autima unit). Mean intracardiac P wave amplitude was 2.0 mV ± 0.78/SD, range 0.7–3.6 mV, and mean atrial and ventricular pacing thresholds were 1.0 V and 0.5 V, respectively. Fourteen patients had completely successful A‐V pacing during a follow‐up period of 4‐33 months (mean 7 ± 2.7 months). Two failures were associated with malposition of the atrial crown and occurred exclusively with the Cordis 208A generator. In both patients generator replacement using a more sensitive unit (Siemens‐Elema 625) resulted in successful VAT pacing for most of the time, Complete failure of A‐V pacing occurred in only one patient who died from coronary artery disease after four months of follow‐up. Thus, all of the remaining 36 patients achieved long‐term (6 months) satisfactory physiological pacing using this new lead. We conclude that the “Crown of Thorns” electrode is a successful single‐pass unipolar lead and can be used with all types of dual chamber generator for all modes of pacing.
The Ventricular Endocardial Paced Evoked Response
Authors: DONALDSON ROBERT M. , RICKARDS ANTHONY F.
Published: July 2006

The endocardial ventricular evoked response which follows delivery of a unipolar stimulus down the sensing electrode is remarkably uniform, and is of slightly longer duration at the base than at the apex of the heart. As the same lead is used for both pacing and sensing, it is possible to record the evoked T wave representing dominantly local repolarization which follows a pacing‐induced depolarization from the same site. Studies of the pacing evoked response following administration of drugs with class 3 mode of action are similar to those obtained by monophasic action potential recordings, and suggest that myocardial repolarization can be accurately assessed by this technique. The stimulus to evoked T wave timing has been used to design a pacing system which offers the advantage of physiological control of pacing rate, independent of atrial activity, using a conventional endocardial electrode lead system. The potential advantages of this system are reviewed.
Localization of the Accessory Pathway in the Wolff‐Parkinson‐White Syndrome from the Ventriculo‐Atrial Conduction Time of Right Ventricular Apical Extrasystoles
Authors: WEISS JAMES , BRUGADA PEDRO , ROY DENIS , BÄR FRITS W.H.M. , WELLENS HEIN J.J.
Published: July 2006

In 18 consecutive patients with the Wolff‐Parkinson‐White syndrome undergoing electrophysiologic study, the ventriculo‐atrial conduction time of right ventricular apical extrasystoles which advanced atrial activation during circus movement tachycardia was studied in relation to accessory pathway location. Accessory pathway location was determined by delta wave morphology during maximal pre‐excitation, mapping of alrial activation during circus movement tachycardia and ventricular pacing, the effect of bundle branch block on ventriculo‐atrial conduction time during circus movement tachycardia, and the effect of pacing from different sites in the atria on the stimulus‐to‐delta wave interval. In 7 patients with septal accessory pathways, ventriculo‐atrial conduction time was similar during circus movement tachycardia and following right ventricular apical extrasystoles (mean difference 0 ± 6 ms, range ‐5 to + 10 ms). In contrast, in 11 patients with a left free wall accessory pathway, ventriculo‐atrial conduction time increased by 46 ± 15 ms (range 15 to 65 ms) following right ventricular apical exlrasystoles. Therefore, measurement of the ventriculo‐atrial conduction time of right ventricular extrasystoles during circus movement tachycardia provides an easy way to distinguish between septal and left free wall accessory pathways. This finding may be of particular use in determining the location of concealed bypass tracts.
Transvenous Pacemaker Insertion with a Zero Dislodgement Rate
Authors: MORSE DRYDEN , YANKASKAS MARY , JOHNSON BURT , SPAGNA PASCHAL , LEMOLE GERALD M.
Published: July 2006

A non‐retractable transvenous screw‐in lead which gives both stability of placement and low acute and chronic stimulation thresholds was used in 64 patients during the period April, 1979 to June, 1981. The average threshold at implant was 0.7 volts; the current threshold average was .86 milliamps with the pulse width at the standard setting for the pacemaker employed. Chronic thresholds were usually below the lower programmable limit of the pacer as tested at 3 months. In one patient, the fact that the screw was fixed in the exposed position caused trouble. The lead became knotted in the superior vena cava and was removed by thoracotomy. Although this experience with the Osypka lead was not entirely satisfactory, newer developments with retractable leads may make the principle more acceptable.
Two‐Dimensional Echocardiographic Localization of a Malpositioned Pacing Catheter
Authors: TOBIN ALANDRA M. , GRODMAN RICHARD S. , FISHERKELLER MARK , NICOLOSI ROBERT
Published: July 2006

The precise intracardiac localization of transvenous pacing catheter electrodes is sometimes difficult yet crucial to patient management. We describe a patient in whom standard indirect studies failed to locate a malpositioned pacing catheter. Two‐dimensional (2‐D) echocardiographic examination revealed its entire aberrant course, from the right atrium, across the interatrial septum, through the mitral valve and on to the apex of the left ventricle. The value of this technique is reviewed.
Physiological Benefits of Atrial Synchrony in Paced Patients
Authors: SUTTON RICHARD , MORLEY CHRISTOPHER , LU CHAN SIEW , PERRINS JOHN
Published: July 2006

Au cours ?une période de cinq ans, nous avons comparé la stimulation ventriculaire et la stimulation. “physiologique” chez 50 malades. Dans 17 eas de stimulation de type DVI, le débit systolique était plus éevé que dans la stimulation VVI, (P < 0.005), de même la pression télédiastolque du ventricule gauche était plus basse (P < 0.05). Chez 44 maJades la performance au cours de ľexercice était meilleure avec la stimulation VDDJDDD (P < 0.01). Ces effets se sont confirmés à long terme. La dyspnée était moindre (P < 0.01) et ľimpression de “bien‐être”était confirmée (P < 0.01) avec la stimulation physiologique. Nous concluons que la stimulation cardiaque synchrone àľoreillette est le mode de choix en ľabsence de contre‐indications.

Over a five‐year period, hemodynamic exercise capacity studies and a randomized controlled trial have been performed in a total of 50 patients. DVI vs. VVI pacing showed an increase in stroke work index (P < 0.005) and a fall in left ventricular filling pressure (P < 0.05) in 17 patients. VDDJDDD pacing vs. VVI showed an exercise capacity benefit in 44 patients (P < 0.01) including 8 patients with sinus node disease and a lower peak heart rate (P < 0.02). Maintenance of benefit was also shown of VDDJDDD pacing in the longer term (13 months) vs. acute (P ‐ NS). The controled trial VDDJDDD vs. VVI showed benefit in shortness of breath (P < 0.01) and general well being (P < 0.01). It is concluded that atrial synchronous ventricular pacing (VDDJDDD) is the mode of choice in suitable patients.
Physiologic Benefits of Rate Responsiveness
Authors: SHAPLAND J.E. , MACCARTER D. , TOCKMAN B. , KNUDSON M.
Published: July 2006

Ľaugmenfation du besoin métabolique ou cours de ľexercice est fournie par une hausse du débit cardiaque et de ľapport ?oxygène. Les malades porleurs ?un stimuluteur à fréquence fixe ne peuvent pas augmenter la fréquence cardiaque dont dépend ľaugmentation du débil systolique. Nous décrivons un stimulateur capable ?augmenter sa fréquence suivant ľuctivité auriculaire. Par cette méthode nous avons observé un meilleur débit cardiaque, de ľordre de 55 ± 3.7%. Ce stimulafeur améliore donc la performance cardiaque pendant ľexercice.

Increases in metabolic demand in response lo routine activities and exercise are met througb grealer cardiac output ond oxygen delivery. Putienls with fixedrate pacemakers cannot increase heart rate and must rely solely on increases in stroke volume to provide the necessary adjustments in cardiac output. These compensatory strofte volume increases limit the fixedrate pacemaker patient's ability to meet the demand of their daily routine. A physiological, rate responsive pacemaker was studied and it was found to increase maximum exercise tolerance from 4.4 ± .62 METS paced VVI at 65 ppm to 8.1 ± .71 METS when the same patients were paced rate responsively at an average rate of 91 ± 3.8 ppm. Animal studies were used lo quantify the limitation in stroke volume reserve. Maximum increases of 55.8 ± 3.7% over resting vulues were seen in animals in complete heart block at pacing rates of 100 ppm during strenuous exercise. Higher pacing rates increased cardiac output at the same exercise intensity, from 4.94 ± .72 Ipm at 100 ppm lo 7.66 ± 1.02 Ipm at 250 ppm. A pacemaker that increases pacing rate in response to grealer metabolic demand will maintain stroke volume and enddiastolic volume at near normal voiues while providing significant improvement in cardiac output and work capacity.
Management of Tachyarrhythmias with Dual‐Chamber Pacemakers
Authors: MEDINA‐RAVELL VICTOR , CASTELLANOS AGUSTIN , PORTILLO‐ACOSTA BOLIVAR , MADURO‐MAYTIN CASTOR , RODRIGUEZ‐SALAS LUIS , HERNANDEZ‐ARENAS MANUEL , LA SALLE‐TORO RAUL , MENDOZA‐MUJICA IVAN , ORTEGA‐MALDONADO MANUEL , BERKOVITS BAROUH V.
Published: July 2006

Des stimulaleurs multiprogrammables AV séquentiels de type “double‐demande” (DVI, MN) ont été implantés chez 23 patienls porteurs ?anomalies variées de tachycardies supraventriculaires. De plus, des stimuloteurs AV séquenfiels à paire “nonobligée” (DVI, MN e(DDD, M) ont été utilisés pour le traitement de lachyarhythmies ventriculaires. Nous avons observé que ľexpérience avec ee type de stimulateur multiprogrammable est favorable chez les patients sans fibrillation auriculaire chronique, qui ont besoin ?un stimutafeur et qui nécéssitent un froilement anti‐tachycardique. Ľévolution des stimulateurs du type DDD contribuera sans doute à un traitement encore plus éfficace.

Multi‐programmable dual‐demand AV sequential (DVI, MN) pacemakers were implanted in twenty‐three potients (in one of them a DVI, MN unit was used as a VVI, MN with the aid of an atrial plug) with suproventricular tachycardias after electrophysiological studies revealed a great voriety of AV reentry circuits. The latter included tachycardios involving accessory pathways of the Kent type, manifest or concealed Wolff‐Parkinson‐White syndromes, nodo‐ventricular (Mahaim) tracts, “enhanced” AV node for extra AV nodal) pothwaysand dual AV pathways. In addition, multiprogrammable “non‐committed” AV sequential (DVI, MN and DDD, M) pacemakers were permanently implonted to treat different forms of ventricular tachyarrhythmias that included: torsode de pointes in the Romano‐Ward syndrome and Chagas' cardiomyopathy, ventricular tachycordia which is bradycardia‐dependent (in Chagas' cardiomyopathy) and reciprocal beats indueed by, and producing severe hemodynamic derangements in a patient with a conventional VVI unit. With smallsize multiprogrammable units, arrhythmias may be treated by changing parameters non‐invasively. By temporary inhibition, one may analyze the underlying rhythm and pacemaker dependency. In potients without chronic atrial flutterJfibrillation who require pacing and possibly tachyarrhythmia control, our experience with multiprogrammable “non‐committed” AV sequential pacing has been very satisfactory. The evolution toward newer pacing modes which provide atrial sensing and trackmg (DDD), and thus preserve AV synchrony over a wider range of atrial rates, may contribute even further to successful patient management. This may be applicable to pediatric patients as well.
Principles of Multimode Pacing
Authors: TARJAN PETER P.
Published: July 2006

En dépit de la proliferation des systémes de stimulation dits physiologique, ľanalyse de leur fonction par ľéléctrocardiogramme est restée complexe. Une meilleure méthode ?analyse est done necessaire pour aider le clinicien à mieux comprendre les systemes DDD. Le dialogue entre fabricant et clinicien doit done rester toujours ouvert.

Although physiologic pacing systems have multiplied recently, their functional evaluation by ECG analysis remains an area of relative complexity. More thorough and detailed specifications of operation are necessary to aid the clinician in his effort to understand and assess the function of a DDD pacer. Elimination of cross‐talk via various available methods should simplify interpretation. Awareness by physicians will provide the necessary feedback to the designers to create more physiologic systems in the future.
Detection and Characteristics of Retrograde P Waves
Authors: RIPART A. , PIOGER G.
Published: July 2006

Le systéms de détection de ľactivité auriculaire present dans les stimulaleurs actuels VDD ou DDD ne permet pas de faire avec certitude to distinction entre ľactivit? aurieulaire normale et rétrograde. Il apparait done nécessaire de mettre au point un systéme efficace de détection et de prévention des tachycardies induites par les stimulateurs, qui ne limitera pas les bénéfices hémodynamiques apportés par ces appareils.

Clinical evaluation performed on an external prototype of a programmabie VDD pacemaker showed a high risk of induction of pacemaker‐mediated tachycardia. In these tests tachycardia was observed following magnet removal, premature atrial and ventricular complexes, myopotential oversensing, detection of electri‐cal interference and other events. The high risk and poor predictability of pacemaker‐mediated tachycardia suggest that VDD (or DDD) pacemakers should provide automatic means to control this kind of tachycardia without undue loss of the hemodynamic benefits which can be provided by these units.
Prevention of Pacemaker Mediated Arrhythmias
Authors: ELMQVIST HAKAN
Published: July 2006

Les tachycardies de type réentrée induites par les stimulateurs à deux chambres sont présentées. Les méthodes utilisées pour prévenir ces arythmies sont énumérées. La méthode la plus efficace consiste à reprogrammer la période refractaire de la détection ouriculaire alin ?éviter la stimulation ventriculaire induite par une onde P rétrograde.

Pacemaker mediated re‐entry tachyarrhythmias and their causes are discussed. Several methods to prevent these arrhythmias are presented. It is shown that the most efficient method incorporates a long refractory period of the atrial detection after ventricular depolarization. The benefits of a short A‐V delay after atrial sensing are discussed.
Dual‐Chamber Committed Mode Pacing
Authors: CALFEE RICHARD V.
Published: July 2006

La prolifération de slimulateurs AV séquentiels est responsable de ľexistence de plusieurs modes de stimulation DVI. La distinction entre “paire obligée” et “paire non‐obligée” est expliquée. En plus, un mode di (“hybride” a élé mis en production. C'est le mode des paires demi‐obligées. Ce mode de stimulation divise ľintervalle AV en deux: une partie non‐physiologique suivie ?une partie physiologique oúľinhibition ?un stimulus ventriculaire est possible aprés un recueil de ľactivité ventriculaire.

The proliferation of dual‐chamber pacemakers has resulted in several different modalities of DVI pacing. A distinction is made between “committed” and “noncommitted” modes, and the differences are presented. In addition, a new hybrid mode has been developed which has been termed “semi‐committed” and is currently being introduced. The semi‐committed mode divides the AV interval into an early non‐physiologic interval and a later “physiologic” interval which enables inhibition of ventricular output following a sensed ventricular event.
Comparison of Pacing Electrodes of Different Shape and Material—Recommendations
Authors: IRNICH WERNER
Published: July 2006

Plusieurs suggestions pour la comparaison des différenles électrodes de stimulation sont énumérées. Dans Ja majorité des rapports cités, ces comparaisons n'atteignent pas leur but, parce que les paramètres de mesure utilisés ne sont pas constants. Un calendrier pour les mesures de seuil aigu et chronique est proposé rheobase et chronaxie est aussi expliqué. EnFin le rôle de la polarisation ?électrode est disculé.

Recommendations for comparing different pacing electrodes to one another are presented. In most reported studies, such comparisons fall short of the intended gool because they are made with eiectrode parameters that are not constant. The suggestions presented include timetables for acute and chronic threshold measurements, conditions for measuring lead impedance, and the relationship between rheobase and chronaxie. In addition, the effects of polarization of the electrodes are discussed.
Porous Electrodes: Concept, Technology and Results
Authors: MacCARTER DEAN J. , LUNDBERG KATHLEEN M. , CORSTJENS J.P.M.
Published: July 2006

Ľélectrode poreuse a été déVelopée pour améliorer le recueil ainsi que la qualité de la stimulation. Ces électrodes créent une interface au niveau de ľendocarde qui a pour but (1) de diminuer les seuils de stimulation chronique, (2) de faciliter la pénétration de la fibrose dans ľélectrode afin ?éviter les déplacements et (3) de présenter une surface électrolytique importante de contact pour réduire le voltage de polarisation. Les résultats cliniques actuels sonl favorables. Les avantages de ľéiectrode poreuse à long terme restent à décrire.

Porous electrodes were designed and implanted to optimize sensing and pacing performance of the cardiac pacemaker. These eJectrodes were manufactured to create an effective, atraumatic endocardial interface in order to (1) decrease chronic stimulation thresholds and pacemalter current drain; (2) facilitate fibrous protein tissue ingrowth for reduced electrode displacement; and (3) to create a large electroiytic surface area of contact for reduced polarization voltage, thus improving impulse and electrogram transmission. Thus far, clinical results demonstrate reduced long‐term threshold and decreased current drain. Long‐term advantages of porous electrodes remain to be determined.
The Carbon Tip Electrode
Authors: ELMQVIST HAKAN , SCHUELLER HANS , RICHTER GERHARD
Published: July 2006

Le developement de ľelectrode au carbone et les seuils de stimulation à long terme sont presentés. En comparaison avec les matériaux ?électrodes usuels, ľélectrode au carbone permet des seuils de stimulation à long terme plus bas. Chez 43 patients, il a été possible de diminuer le voltage des stimulateurs lorsque ľélectrode au carbone était utilisée. Ce matériau favorise done ľutilisation des stimulateurs à basse énergie.

The development of the carbon tip electrode and its low chronic threshold behavior are described. Compared to presently used electrode material, carbon tip electrodes result in lower chronic stimulation thresholds. In a group of 43 patients, chronic pulse generator output has been favorably reduced in association with this type of electrode. Thus the use of activated carbon tip electrodes may result in the routine implantation of low output pacemakers.
Polyurethane Leads: Facts and Controversy
Authors: SCHEUER‐LEESER MARION , IRNICH WERNER , KREUZER JOACHIM
Published: July 2006

Une comparaison des électrodes de stimulation en polyuréthane et en silicone est présentée. Lorsq́ue ľon compare tes qualités mécaniques et électriques, les qualités de friction et la stabilité hydrolytique, les deux matériaux paraissent capables ?être utilisés comme game des sondes ?électrode. Néanmoins, en raison des craquelures de surface observé'es avecle polyuréthane il est nécessaire ?obtenir des surfaces aussi précises et parfaites que possible. De plus, les manoeuvres de torsion et de courbure doivent être évitées lors de ľimplantation. Enfin, la surveillance à long terme doit être assurée ?une façon routiniere.

A comparison of polyurethane and silicone cardiac pacing leads is presented. In comparing mechanical and electrical properties, friction coefficient and hydrolytic stability, both are highly qualified for use as electrode sheaths. The occurrence of surface cracking of polyurethane leads is examined. Several suggestions are proposed for dealing with the manufacture of new leads, the technique of implantation, and the follow‐up required for successful surveillance.
Orthogonal Electrogram Sensing
Authors: GOLDREYER BRUCE N. , KNUDSON MARK , CANNOM DAVID S. , WYMAN MILFORD G.
Published: July 2006

Le recueil de ľéléctrogramme intracardiaque donne ľinformation nécessaire aux systèmes de stimulation à la demande. Les troubles du recueil surviennent dans près de 50% de stimulateurs unipolaires, ceux de ľoreillette sont encore plus fréquents. Le recueil par électrode orthogonale ne demande pas de contact avec le myocarde et on obtient de hauts potentiels ?origine auriciilaire avec rejection totale des pontentiels ventriculaires. Ce système permet la sequence ?activation aussi bien que la vérification de la capture.

Intracardiac electrogram sensing is the afferent limb of demand pacing systems. Under‐ and over‐sensing at the ventricular level has been demonstrated in almost 50% of implanted unipolar pulse generators, and atrial eJectrogram sensing problems are more common. A unique dedicated sensor employing noncontacting and circumferentially placed orthogonal electrodes was tested at both the atrial and ventricular levels. Electrograms demonstrated voltages similar to those recorded from contacting electrodes, but with complete far‐field rejection of signals from the opposite chamber. Orthogonal electrograms allowed for activation sequencing and capture verification as well.
“Crown of Thorns” Single Pass Lead ‐ Clinical Results
Authors: SOWTON EDGAR , WAINWRIGHT R.J. , CRICK J.C.P.
Published: July 2006

Vingt‐quatre patients ont ete tracés pendant une période ne dépassant pas deux ans (14 mois en moyenne) àľaide ?une sonde auriculo‐ventriculaire unique. Les récents progrès de fabrication permettpnt ľinsertion percutanée dans la veine sousclavière. Les seuils de stimulation et le recueil pour ľoreiilette et pour le ventricule restent satisfaisonts pour plusieurs types de stimulateurs. Aucune complication liée à cette sonde n'a été observée chez 277 mois/patients. Nous concluons donc que cette sonde auriculoventdculaire unique est utilisoble pour ľimplantation à long terme des stimulateurs physiologjques.

Twenty‐four patients have been treated for periods of up to two years (mean 14 months) with this single pass electrode for physiological pacing. Manufacturing refinements now allow percutaneous insertion into the subclavian vein. Pacing thresholds and sensing signals from both atrium and ventricle have remained satisfactory for a wide variety of different physiological pacemakers. No complications specifically related to the lead have occurred in a total of 277 patient months. We conclude that this single pass electrode is suitable for long‐term implantation and can provide physiological pacing with present day stimulators.
Results, Problems and Perspectives with the Autoregulating Pacemaker
Authors: CAMMILLI L. , ALGIDI L. , SHAPLAND E. , OBINO S.
Published: July 2006

Ces variations peuvent être utilisées pour réguler la fréquence de stimulation op‐timale. Des recherches continues sont nécessaires pour perfectionner ce système; surtout en ce qui concerne la surface de ľélectrode et ľamelioration du contrôle et de la réponse du capteur.

Experi‐mental in vitro testing coupled with animal and clinical studies have shown that a pH sensor may sense acute changes in pH occurring in response to exercise. This signal may in turn be used as a determinant for optimal pacing rate. Further investigation into membrane coating of electrodes and algorithm testing is necessary to maximize sensor response and control.
Self‐Inhibition of an AV Sequential Demand (DVI) Pulse Generator Due to Polyurethane Lead Insulation Disruption
Authors: SANFORD C. FAGG
Published: July 2006

Self‐inhibi lion of bipolar DVIAV‐sequentia I pacemakers has been attributed to eleclrode malposition, although the potential for self‐inhibition due to current leakage has been recognized. Previous cases of current leakages due to insulation defects in bipolar VVI ventricular demand systems have usually presented as abnormal sensing or pacing function without a change to actual unipolar sensing and pacing. This article describes a case of disruption of the insulation of polyurethane bipolar atrial and ventricular leads by silk ligatures, resulting in unipolar atrial and ventricular pacing and self‐inhibition of ventricular output of a DVI pulse generator. This case emphasizes the importance of avoiding any application of suture material directly to polyurethane leads. This case also emphasizes the importance of monitoring pacemaker artifact amplitude and axis in patient follow‐up.
Implant Experience with Unipolar Polyurethane Pacing Leads
Authors: BYRD CHARLES L. , MCARTHUR WILLIAM , STOKES KEN , SIVINA MANUEL , YAHR WILLIAM Z. , GREENBERG JACK
Published: July 2006

A total of 905 unipolar polyurethane pacing leads have been implanted by the first author's group, between April 1978 and February 1982, with a mean implant time of 1.4 years. Twelve leads were explanled and analyzed. Eleven of the explanled leads exhibited some degree of surface damage or “frosting.” Of the 11, five atrial (Medtronic 6991 U) and one ventricular (Medtronic 6971) lead suffered complete insulation failure. One lead was completely free from surface damage, Clinically, insulation failure presented as muscie stimulation and/or battery depletion. Surface damage appears to be due to an environmental stress cracking (ESC) mechanism. ESC requires both a surface active agent from the hostile biological environment, and stress in excess of a threshold value. The minor surface damage or “frosting” of the eleven explanted leads was typically 10 to 15 microns deep on leads implanted about one year, although one device (15 months) had 30 micron cracks. No lead failures in this series were attributed to this shallow cracking mechanism. The severe cracking of the six Medtronic leads leading to insulation failure was thought to be due to the unusually high tensile stresses imposed by manufacturing processes and ligatures. The incidence of failure was 7% (5/74) for the Medtronic 6991 U and 0.2% (1/454) for the Medtronic 6971, Medtronic lead manufacturing processes have been modified to reduce the high residual tensile stresses and a fixation sleeve has been added to reduce ligature stress.
Pulmonary Emboli from a Platelet‐rich Thrombus Attached to a Pacemaker Electrode
Authors: DAVIS GARY , KAPLAN KERRY , KWAAN HAU C.
Published: July 2006

A patient with recurrent, fatal pulmonary emboli originating from thrombus attached to a permanently‐implanted pacemaker electrode is described. While most throm‐boemboli are composed predominantly of fibrin and erythrocytes. histologic and immunologic studies showed this thrombus to be rich in platelets. A possible therapeutic approach to this rare situation is discussed.
Rectus Abdominis as a Source of Myopotentials Inhibiting Demand Pacemakers
Authors: GIALAFOS JOHN , MAILLIS ANTHONY , BASIAKOS LASKOS , AVGOUSTAKIS DIMITRIS
Published: July 2006

We examined four patients with a demand pacemaker who exhibited transient symptoms of vertigo while trying to rise from the supine position. In two of these there was an epicardial pacing system with the pacemaker in the abdominal wall superficial to the rectus abdominis muscle; in the other two cases the pacing system was transvenous with the pacemaker superficial to the right pectoralis major muscle. It was found that the “pseudovertigo” was due to pacemaker inhibition caused by rectus abdominis myopotentials in all four patients. Changing the pacing mode from demand to fixed‐rate resulted in the disappearance of all symptoms at rest and during exercise.
Comparative Effectiveness of Pacing Techniques for Termination of Well‐Tolerated Sustained Ventricular Tachycardia
Authors: FISHER JOHN D. , KIM SOO G. , MATOS JEFFREY A. , OSTROW ELIOT
Published: July 2006

Ventricular tachycardias can be terminated by a variety of pacemaker techniques, including rapid and slow stimulation. Fast tachycardias are typically poorly tolerated, and require prompt intervention, usually with rapid pacing. Termination of ventricular tachycardia by slow or single capture pacemaker stimulation techniques is attractive, because of its presumed safety and the possibility of using simple implantable pacers. To identify factors favoring termination, single capture stimulation was used in 390 episodes of ventricular tachycardia in 21 patients, 16 with coronary artery disease, able to tolerate ventricular tachycardia forseveral minutes. Single capture stimulation terminated 223 episodes (57%) in 18 patients, and two were accelerated. Of 157 episodes exposed to 2–3 programmed extrastimuli or rapid pacing 149 (94%) were terminated and 7 were accelerated. Direct current cardioversion was needed in 12 episodes. Without medications, only two patients tolerated VT. Only one patient had reliable termination with single capture stimulation over several days. Systolic blood pressure was similar in episodes terminated and not terminated by single capture stimulation, but the ventricular rate was significantly lower in episodes terminated, 116 ± 19 vs. 133 ±24 (p<0.001). Termination of ventricular tachycardia was not affected by QRS morphology. Single capture termination of ventricular tachycardia is largely unpredictable, with limited reproducibility over a period of time. Although comparatively safe, single capture techniques are not likely toprove useful in the long‐term treatment of many patients with recurrent ventricular tachycardia.
The Use of Amiodarone in Children
Authors: COUMEL PHILIPPE , LUCET VINCENT , NGOC DIEN DO
Published: July 2006

Our use of amiodarone in 200 patients during an 8‐year period confirms our previous experience which indicated that the drug was close lo being the ideal antiarrhythmic agent in children's arrhythmias. Its absence of cardiac toxicily, its powerful antiarrhythmic properties, its depressive effect on the AVnodal conduction, combined with its beta‐inhibitory effect makes it effective and harmless in practically all forms of alrial, junctional and ventricular arrhythmias, whatever the reentrant or automatic mechanism of the arrhythmia. The metabolism is much faster in children than in adults, making the drug active in a few hours, with a lesser prolonged duration of act ion. Though there is practically no limitation forits use on a short‐ or mean‐term basis, the long‐term use must be limited to truly refractory arrhythmias, a situation which is rarely encountered, In such cases, combining amiodarone with conventional therapy allows a decrease in the maintenance dosage and a lower incidence of extracardiac side effects.
Pseudo‐QT Prolongation, Artifactual Electrocardiographic Patterns Produced by Transduction of Cardiovascular Motion
Authors: STEWART WILLIAM J. , LEVINE PAUL A. , SCHICK EDGAR C.
Published: July 2006

Four cases are presented in which focal electrocardiographic artifacts mimicked QT segmenl prolongation with giant T and U waves. Displacement of the recording electrode by a subjacent cardiovascular impulse was the cause of this distortion. The artifacts could be reproduced at the bedside by in ten tional changes in patient posture and electrode slability. Phasic variation in electrode contact with the electrolyte gel and skin, or intermittent contact between the heart and chest wall, causes shifts in the electrical properties of the recording system which may distort the recorded waveforms during the repolarizalion phase of the electrocardiogram.
Atrial Pacing: Intracardiac Conduction Assessed by His Bundle Electrograms Acquired from the Permanent Atrial Electrode at Implantation
Authors: O'KEEFFE DECLAN BARRY , GEDDES JOHN S.
Published: July 2006

His bundle electrograms were recorded from conventional J‐shaped atrial electrodes at implantation in twelve consecutive patients who had sinus node disorder. Five patients with impairment of atrioventricular conduction, received atrioventricuIar (DVI) pacemakers. His bundle recording by this method is simple and reliable, avoids the discomfort of the conventional technique, and represents a new application for the well established atrial “J” electrode.
Comparison of Lead Complications with Polyurethane Tined, Silicone Rubber Tined, and Wedge Tip Leads: Clinical Experience with 822 Ventricular Endocardial Leads
Authors: KERTES PAUL , MONO HARRY , SLOMAN GRAEME , VOHRA JITU , HUNT DAVID
Published: July 2006

Lead‐related complications have been prospectively studied for 602 unipolar tined endocardial ventricular pacemaker leads implanted over a five‐year period. No differences were noted in overall complication rates between 238 polyurethane insulated leads (4.2%) and 364 silicone rubber insulated leads (3.6%). Comparing the total series of 602 tined leads to a retrospective survey of 220 wedge tip leads, a marked reduction in dislodgements (0.3% vs. 7.7%, P<0.001) and reoperations (2.0% vs. 15.0%, P<0.001) was found using tined leads. We conclude that tined ventricular leads are far superior to wedge tip leads with respect to lead complications.
Sustained “Slow‐Fasf” and “Fast‐Slow” AV Nodal Re‐entrant Tachycardia in a Patient with Recurrent Supraventricular Tachycardia
Authors: KERR CHARLES R.
Published: July 2006

A case is presented of a 21‐year‐old woman with recurrent paroxysmal supraventricular tachycardia. Eleclrophysioiogic study demonstrated the presence of both antegrade and retrograde dual AV nodal conduction pathways and both conventional slow‐fast and atypical fast‐slow forms of the AV nodal re‐entrant tachycardia could be induced. Both tachycardias were successfully suppressed with a combination of digoxin and verapamil.
Role of Electrophysiologic Testing in the Therapy of Ventricular Arrhythmias
Authors: DOHERTY JOHN U. , JOSEPHSON MARK E.
Published: July 2006

The past decade has witnessed important advances in the understanding of the mechanism underlying ventricular arrhythmias. It has become clear that sustained ventricular arrhythmias can generally be reproduced with programmed ventricular stimulation in the clinical elec‐trophysiology laboratory. False positive results may, however, occur with very vigorous stimulation techniques, particularly in patients without documented arrhythmias. False negative results are not infrequent in victims of cardiac arrest. Ability or inability to initiate ventricular tachycardia duringacute and chronic drug testing has predicted clinical failure or success, at least for conventional antiar‐rhythmics. Patients with sustained ventric ular tachycardia and cardiac arrest occurring outside the peri‐infarction period are those most likely to benefit from study. Conventional antiarrhythmic agents are successful in about one‐third of patients with a high degree of concordance among these drugs. Amio‐darone is frequently effective in patients with drug‐refractory ventricular arrhythmias. However, its efficacy cannot be predicted by programmed stimulation. This is in striking contrast to Type 1A anti‐arrhythmic agents.
Mechanisms for the Success and Failure of Pacing for Termination of Ventricular Tachycardia: Clinical and Hypothetical Considerations
Authors: FISHER JOHN D. , KIM SOO G. , WASPE LAWRENCE E. , MATOS JEFFREY A.
Published: July 2006

The effectiveness of pacing techniques for termination of ventricular tachycardia is well established, and of great value in the elec‐trophysiologic laboratory, and, to a more limited degree, for chronic therapy using implanted anti‐tachycardia devices. Although it appears that most clinical ventricular tachycardias are due to reentrant mechanisms, responses to antitachycardia pacing have often been difficult to understand. In this paper, clinical observations are correlated with hypothetical constructs and considerations, in an attempt to derive some general principles related to the success and failure of pacing for ventricular tachycardia. In these analyses, it appears that properties of conductivity and refractoriness in the myocardium are as important as the properties of the tachycardia circuit. Programmed extrastimuli or rapid pacing result in shortening of the effective refractory period of the myocardium, together with depressed conduction velocity of the stimulated wavefront. However, the changes in wavefront conductivity do not occur in step with changes in the effective refractory period; as a result, the stimulated wavefront arrives at the tachycardia circuit in a pattern which differs from the stimulation pattern. In general, it appears that termination of the tachycardia is favored when the stimulated wavefront arrives at the tachycardia circuit at a point when it cannot enter the circuit in an antegrade direction. These conditions are favored by a refractory period in the circuit which is moderately long compared to that of the myocardium. Constructions explaining the observation of a tachycardia termination zone are presented, together with explanations for failure to achieve termination, and for various patterns of acceleration.
The Electrophysiological Substrate of Atrial Fibrillation
Authors: SIMPSON ROSS J. , FOSTER JAMES R. , MULROW JOHN P. , GETTES LEONARD S.
Published: July 2006

The electrophysiological substrate that predisposes the human atrium to sustain alrial fibrillation is incompletely understood. However, abnormalities of atrial size, refractory period and conduction are important precursors to this arrhythmia. The propensity of various disease states, cardio active drugs and the autonomic nervous system to potentiate atrial fibrillation may be explained by changes in these electrophysiological properties.
The Role of Rate Hysteresis Pacing in the Hypersensitive Carotid Sinus Syndrome
Authors: MORLEY CHRISTOPHER A. , PERRINS E. JOHN , CHAN SIEW LU , SUTTON RICHARD
Published: July 2006

The ability of rate hysteresis programming with the escape interval longer than the automatic interval lo reduce the hypotensive response to carotid sinus massage at the onset of ventricular pacing was studied in six patients paced for carotid sinus syndrome. Rate hysteresis significantly reduced this hypotensive response and abolished spontaneous symptoms in two patients and symptoms reproduced by carotid sinus massage in four patients.
Stability of Permanent Transvenous Dual‐Chamber Pacing Electrodes During Cardiopulmonary Resuscitation
Authors: MADIGAN NIALL P. , MUELLER KARL J. , CURTIS JACK J. , WALLS JOSEPH T.
Published: July 2006

For long‐term dual‐chamber permanent pacing, atrial and ventricular lead stability is essential. In our overall experience with such pacing systems, four patients suffered cardiac arrest at a time distant from their pacemaker implantation. Since all four patients received prolonged closed chest cardiopulmonary resuscitation, we analyzed these events to determine whether dual‐chamber endocardial electrodes would remain stable in such traumatic conditions. Reliable atrial and ventricular lead position was confirmed at autopsy in the three patients whose resuscitation attempts were unsuccessful and, in the fourth patient, by continued normal lead position and pacing function post‐resuscitation. The keys to this stability include the use of tined atrial and ventricular endocardial leads and specific maneuvers at the time of implantation to verify fixation. Long‐term stability of presently available endocardial leads in dual‐chamber pacing systems can thus be anticipated.
Inframammary Pulse Generator Placement for Maximizing Cosmetic Effect
Authors: BELOTT PETER H. , BUCKO DENNIS
Published: July 2006

Today with the expanding clinical role of cardiac pacing and more advanced methods of detecting pacing problems, more and more young patienls are being idenlified as Candidales for permanenl pacing. Concern has been expressed by young female patients over the cosmetic effects of pacemaker surgery. Two young female patients were evaluated from a physiologic and cosmetic point of view. The electrodes were placed via the percutaneous approach. The pulse generator was treated as a breast implant using The usual recommended plastic surgeon's inframammary approach. In both cases, optimal cosmetic effect was achieved without any external evidence of the pacemaker system.
Determination of the Left Bundle Branch Refractoriness by Distal His Bundle Pacing in Patients with Left Bundle Branch Block
Authors: BELHASSEN B. , PELLEG A. , MOTTÉ G. , LANIADO S.
Published: July 2006

Electrophysiological studies were carried out in two patients with an idiopathic leff bundle branch block. Consisfenl distal His bundle pacing resulted in the normalization of the QRS complex in both pa lien ts. Extrastimulation during basic distal His pacing at several cycle lengths was carried out successfully. Using this technique, the refractory periods of the left bundle branches were measured and found to be within the normal range. In addition, they decreased with the shortening of the basic cycle length. These results demonstrated the possibility of determining the refractoriness of the left bundle branch by His bundle pacing in patients with left bundle branch block. Hypotheses are postulated about the presumed location of the lesion responsible for the left bundle branch block.
Evidence that AV Nodal Re‐Entrant Tachycardia Does Not Require Participation of the Entire AV Node
Authors: HARIMAN ROBERT J. , CHEN CHIA‐MAOU , CARACTA ANTONIO R. , DAMATO ANTHONY N.
Published: July 2006

Electrophysiologic studies in a case of A V nodal re‐entrant tachyca rdia showed thai a programmed alrial premature depolarization induced during the tachycardia did not change the tachycardia cycle but caused a delay in the following atrial echo. Analysis of such a phenomenon suggests that the atrial premature depolarization was conducted to the upper part of the AV node but not to the site of the re‐entry. Therefore, AV nodal re‐entry can persist without the participation of the upper part of the AV node. This case illustrates that the upper common pathway connecting the dual AV nodal pathways cranially is most likely located within the AV node and consists of A V nodal tissue.
The Repetitive Ventricular Response: Relationship to Ventricular Fibrillation Threshold in Dogs
Authors: JONES DOUGLAS L. , KLEIN GEORGE J. , GULAMHUSEIN SAJAD , JARVIS EILEEN
Published: July 2006

The experiments investigated the hypothesis that the occurrence of repetitive ventricular responses elicited by the ventricular extrasystole (VES) technique are an indicator of ventricular vulnerability to fibrillation, A comparison was made between the incidence of repetitive responses elicited by the VES technique and the minimum electrical energy (VFT technique) necessary to elicit repetitive responses and ventricular fibrillation in normal dogs, dogs with acute infarction, and dogs with chronic infarction. The VES technique produced repetitive responses in 14 of 46 sites. Responses were of at least three types: (1) bundle branch re‐entry: (2) activation at the pacing site, and (3) activation at the infarct zone. In contrast repetitive responses and the onset of fibrillation produced by the VFT technique appeared to be a single type with earliest activation at the pacing site. There were no differences in the ventricular fibrillation thresholds between dogs with and without repetitive responses produced by the VES technique. Thus the incidence of VES technique‐induced repetitive responses is not a reasonable predictor of ventricular vulnerability to fibrillation. However, in 2 dogs with lòwer ventricular fibrillation thresholds, repetitive responses originating at the infarct zone were induced by the VES technique. Occurrence of these repetitive responses may be indicative of ventricular vulnerability to fibrillation.