bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term Comparison of Unipolar and Bipolar Pacing and Sensing, Using a New Multiprogrammable Pacemaker System
Authors: BREIVIK KJELL , OHM OLE‐JÖRGEN , ENGEDAL HOGNE
Published: July 2006

Over a six‐month period a comparison was made between uni‐ and bipolar myocardial stimulation thresholds and R‐wave sensitivity in 15 consecutive pacemaker patients. The patients received a new multiprogrammable Cordis 336 A pulse generator, that could be programmed with either uni‐ or bipolar circuitry. In addition, rale, output, sensitivity and pacing mode could be noninvasively programmed. The occurrence of myopotential interference at different sensitivity levels was also studied. Cordis 325–161 bipolar endocardial leads were used in all patients. In one patient, the current output sometimes had to be programmed higher bipolarly than unipolarly to capture the ventricles, otherwise no differences in threshold were found. Acutely, R‐wave sensitivity was superior in 9 patients (60%) in the bipolar mode. Unipolar and bipolar electrograms were equal in 4 (26.7%), whereas unipolar R‐wave sensitivity was best in only 2 (13.3%) of the patients. At a six‐month follow‐up, the same tendency was found. In 5 patients, bipolar sensing was superior to unipolar, while uni‐and bipolar sensitivily was equal in the remaining patients. Myopotential inhibition was never seen in the bipolar mode at highest sensitivity (0.8 mV) even during provocative tests (n = 35) or 24‐hour Holter monitoring (n = 12). In the unipolar mode, 14/15 patients (93.3%) showed inhibition during provocative tests and 12/32 patients (100%) during monitoring at a programmed sensitivity of 0.8 mV. No patients had myopotential inlerference at a sensitivity level of 3.5 mV. All patients have theirpacemakers programmed in the bipolar mode after six months. This study con firms earlier acute data that the bipolar pacing mode is superior to the unipolar mode for permanent pacemaker therapy.
An Electrophysiology Report‐Generating System with Data Base Capabilities
Authors: HIEB BARRY R. , SOUTHWORTH WILLIAM , RUFFY RODOLPHE
Published: July 2006

This article describes the Electrophysiology Report‐Generating system (EPREG) which produces reports of clinical cardiac electrophysiologic studies. Reports generated by EPREG are permanently stored on floppy disk media. Selected information from the reports is used to generate an on‐line data base upon which selective searches may be made. Use of the system saves an estimated 2 to 3 hours per week compared to an equivalent manual approach. The system has been implemented on a programmable word processor (Wang OJS‐140) which is also used for other activities within our medical division.
Atrial Pacing by a Ventricular‐Inhibited (WI) Myocardial Unipolar Pacemaker
Authors: JOHNSON CHARLES D.
Published: July 2006

A patient with sinoatrial node disease is reported who demonstrated inadvertent atrial pacing from a ven‐tricular unipolar myocardial electrode and a WI Intermedics pacemaker. Atrial refractory and vulnerable periods are addressed in this context as possibly providing the environment for an atrial arrhythmia, secondary to competition between the non‐sensed impulse and the unipolar cathodal stimulus falling in the atrial vulnerable period.
Unexplained Syncope—A Diagnostic Pacemaker?
Authors: SHAW DAVID B. , KEKWICK CHRIS A. , VEALE DAN , WHISTANCE TONY W.T.
Published: July 2006

We describe our initial experience with a pacemaker which performs the dual function of registering episodes of cardiac arrest and pacing the heart when necessary. The appartus has a prolonged escape interval (2.30–2.65 seconds) and is capable of counting up to 128 “events.” Twenty‐five patients complaining of infrequent episodes of loss of consciousness have been studied. Blackouts ceased and episodes of ventricular standstill were recorded in 14 cases; the unit helped to establish a non‐cardiac etiology for the attacks in two cases. It is suggested that a bradycardia‐recording facility incorporated into a programmable pacemaker would provide a much needed tool in the diagnosis and management of patients with infrequent episodes of loss of consciousness in whom a cardiac mechanism is suspected but unproven.
Macroreentry as a Mechanism of Atrial‐Induced Ventricular Ectopic Beats: A Laboratory Curiosity?
Authors: IESAKA YOSHITO , LISTER JOHN W. , BLANKSTEIN RONALD L. , GOSSELIN ARTHUR J. , ROZANSKI JOHN J.
Published: July 2006

During electrophysiologic study in a patient, programmed stimulation of the atrium induced fixed coupled ventricularpremature beats on the basis of infra ventricular macroreentry. This type of macroreentry, which was reproducible, appears to have been merely a “laboratory curiosity” and never played a clinical role in this patient with chronic recurrent ventricular tachycardia.
Postmortem Findings and Possible Causes of Unexpected Death in Patients Treated with Intraventricular Pacing
Authors: RAJS JOVAN
Published: July 2006

The study comprises 10 consecutive medicolegal autopsies of patients treated with intraventricular cardiac pacing who died unexpectedly outside of a hospital. The treatment was indicated by AV‐block grade I‐III in eight cases, by bradyarrhythmia in one case, and sick sinus syndrome in the last case. Four patients died during a sudden epileptiform seizure, three were found dead, and three died in their sleep. Recent hemorrhages close to the AV‐node and His bundle were seen in five cases. The local findings in the vicinity of the pacemaker leads were numerous and multiple consisting of thrombosis of the superior vena cava, tortuous and corroded leads, leads attached to the atrial endocardium, constricted orifice of the coronary sinus, and acute ulcerations, endocarditis, shrinking, and ruptures of the cusps of the bicuspid valve. The right atrium of the pacemaker patients was significantly dilated. The mean value of the ratios between right atrial and ventricular length (AV ratio)of the 10 pacemakerpatients was 1.2 in contrast to the mean value of the same ratio of 30 controls, which was 0.6. The A V ratio was particularly increased in patients with lesions of the tricuspid valve and with a long history of cardiac pacing. In 3 of the 30 patients the immediate cause of death was related to anatomical and technical complications of long‐term intraventricular pacing. Such complications were clinically unrecognized thrombosis of the superior vena cava, rupture of the chordae tendinae, and cable breakage.
Atrial Premature Beats with Variable Return Cycle Lengths—A Clue to Sinus Node Re‐entry?
Authors: SQUIRE ANTHONY , STERN ERIC H. , SCHWEITZER PAUL
Published: July 2006

A patient with alrial premature beats (APBs) with variable return cycle lengths is reported. Two rare responses of the sinus node were observed: APBs in which the return and sinus cycle lengths were equal and APBs which were interpolated. Several possible mechanisms for these unusual effects of APBs on the sinus node are discussed. One mechanism which can explain both of these observations is sinus node re‐entry. This possibilify is indirectly supported by documentation of sinus node re‐entry during electrophysiologic studies.
Non‐invasive Evaluation of Ventricular Function and Volumes During Atrioventricular Sequential and Ventricular Pacing
Authors: ROMERO LUIS R. , HAFFAJEE CHARLES I. , LEVIN WILLIAM , DOHERTY PAUL W. , BERKOVITS BAROUH V. , ALPERT JOSEPH S. , SERINO RICHARD , MURPHY JAMES
Published: July 2006

Thirteen patients who all had previously inserted temporary or permanent pacemakers (6, VVI; 7, A‐V sequential) were studied by two‐dimensional echocardiography and radionuclide gated blood pool ventriculography (RVG) for non‐invasive evaluation of cardiac performance. Patients were paced in both the VVI mode and during sinus/atrial or A‐V sequential pacing. Although there was no objective change of the ejection fraction during V‐pacing and atrial/A‐V sequential pacing or sinus rhythm, as has been previously reported, A‐V sequential pacing did result in significant improvement in overall cardiac function and output as judged by radionuclide ventriculography and blood pressure response in most of our patients. An appropriately timed atrial contribution to ventricular systole resulted in improved ventricular function in those individuals with pre‐existing systolic or diastolic myocardiol dysfunction and/or sick sinus syndrome in whom pacemaker therapy was indicated. Radionuclide ventriculography appears to be a reliable, accurate, non‐invasive method that can be used to evaluate patients before implantation of a permanent ventricular or atrioventricular pacemaker in order to decide which pacing mode is best for that particular individual.
Pacemaker Dependence in Transient High‐grade Atrioventricular Block
Authors: ROSENQVIST MÅRTEN , EDHAG K. OLOF
Published: July 2006

In a prospective study 16 patients who had been given a pacemaker because of symptomatic high‐grade atrioventricular block and whose conduction had been recovered were checked for their dependence on the pacemaker. During a follow‐up time ranging from 32 to 158 months (median 62 months) six patients proved to be dependent on the device owing to the development of recurrent stable high‐grade atrioventricular block. The subsequent return of atrioventricular block was evidently not associated with etiology, age, sex, ECG‐pattern or length of follow‐up period. Five additional patients equipped with a bradycardia‐indicating pacemaker all proved to be pacemaker‐dependent after a follow‐up time ranging from 1–20 months (median 7 months), even though atrioventricular conduction had recovered and its presence had been confirmed at regular outpatient checks. It is thus evident that the conventional clinical methods are of limited value for examining the course of conduction defect and assessing the prognosis for patients whose spontaneous cardiac activity has returned after periods of symptomatic high‐grade atrioventricular block. When a bradycardia‐indicating pacemaker was furnished, pacemaker dependence was demonstrated in most of the patients whose atrioventricular conduction had recovered. This confirms that pacing introduced because of symptomatic high‐grade atrioventricular block should not be discontinued even if a conducted heart rhythm has been established and maintained for long periods.
Slight Rate Acceleration in Permanent Rechargeable Nickel‐Cadmium Pacemakers: A Possible Marker of Battery Failure
Authors: FRENCH WILLIAM J.
Published: July 2006

Thirty‐seven rechargeable pacemakers were implanted in 33 patients between 1972 and 1976. Average follow‐up has been 4.9 years. Six patients have had these pacers for an average of 7.8 years. Slight rate acceleration of 3 to 5 beats per minute was demonstrated in 46% of the units; rate acceleration to greater than 80 beats per minute was present in three pacemakers, two of which failed within three months. Although rechargeable pacemakers have performed well, frequent surveillance or replacement is warranted if the pacing rate increases to greater than 80 beats per minute
Management of Pacemaker Circus Movement Tachycardias
Authors: DULK KAREL den , LINDEMANS FRED , WELLENS HEIN J.J.
Published: July 2006

DDD pacemakers were implanted in 11 patients of whom 5 had the capacity to conduct retrogradely to the atrium. Methods to prevent or terminate pacemaker circus movement tachycardia (PCMT) were evaluated in these patients. V‐A conduction was assessed before implantation by incremental right ventricular pacing while recording right atrial electrograms. Following implantation and at quarterly outpatient clinic visits, V‐A conduction and ability to initiate and sustain PCMT were systematically assessed by non‐invasive techniques. PCMT could be induced non‐invasively in all 5 patients. The methods used to reduce and terminate the incidence of PCMT were: 1) decreasing the atrial sensitivity; 2) stressing the V‐A conduction system by programming a high upper rate with an appropriately short A‐V interval; 3) programming a low lower rate; 4) avoiding the Wenckebacb response (by programming a high upper rate); 5) medication; and 6) occasionally by using a magnet. PCMT was controlled in all patients, in 2 patients by programming measures only and in 2 with the addition of medication. One patient who refused medication had to be programmed into another pacing mode. We conclude that : 1) the presence of V‐A conduction is not an absolute contraindication to the use of a DDD pacing system; 2) pacing the ventricle early enough to cause V‐A block was the most useful method to terminate PCMT; 3) future generation DDD pacemakers should prevent initiation of PCMTs while maintaining the possibility to synchronize to exercise‐induced high atrial rates.
Insulation Failure with Bipolar Polyurethane Pacing Leads
Authors: RAYMOND ROGER D. , NANIAN KENNETH B.
Published: July 2006

Between October, 1981, and April, 1983, 200 pacemakers were inserted at Rhode Island Hospital. Forty‐five bipolar polyurethane leads (Medtronic 6972) were positioned in the right ventricle. Three (6.6%) of these leads presented 15 to 18 months post‐implant with insulation failure. The manifestation was inappropriate inhibition of the pacemaker. No obvious cracking was visible on X‐ray or during surgery. All the leads had low impedance, indicative of insulation failure.
The Values and Limitations of Deductive Analysis and Electrophysiological Testing in Patients with Sinoatrial Arrhythmias
Authors: SCHWEITZER PAUL , MARK HERBERT
Published: July 2006

We reviewed the values and the limitations of deductive analysis and electrophysiological testing of sinoatrial arrhythmias (SAA). Both methods have a place in the evaluation of SAA and are complementary. Careful analysis of the surface ECG and the response of the sinus node to various tachyarrhythmias and to atrial premature beats can provide important information about the automatically of the sinus node and sinoatrial and atriosinus conduction. Because of the sporadic nature of some SAA, the surface ECG sometimes must be supplemented by ambulatory ECG recording. This approach improves one's ability to analyze the underlying mechanism and it can also clarify the relation between the SAA and the patient's symptoms. Electrophysiological testing can be employed to reproduce certain SAA and to assess the effects of various drugs on sinus node function. This approach is superior to deductive analysis in the identification of some sinoatrial conduction abnormalities and sinus node reentry. Among the disadvantages of electrophysiological testing are its invasive character and the fact that normal electrophysiological results do not exclude sinus node dysfunction. A definitive clarification of the underlying mechanism of SAA requires direct recording of the sinus node electrogram.
Automatic Tachycardia Recognition
Authors: ARZBAECHER ROBERT , BUMP THOMAS , JENKINS JANICE , GLICK KATHERINE , MUNKENBECK FRAN , BROWN JEFFREY , NANDHAKUMAR N.
Published: July 2006

A microcomputer algorithm for tachycardia identification, suitable for use in un implanted antitachycardia pacemaker, is described. The system employs an atrial and ventricular electrogram, detects a sustained fast rate in either chamber, and awakens the main program to perform detailed analysis of the tachycardia and its immediately preceding beats. The algorithm distinguishes atrial, ventricular, and AV nodal and re‐entrant tachycardia from high rates due to sinus tachycardia. For testing of the program, we used a data base of twenty‐two tape‐recorded and documented arrhythmias provoked during electrophysiologic studies in which atrial and ventricular bipolar electrodes were in place; twenty‐one of twenty‐two wave successfully detected. These included atrial fibrillation, atrial flutter, atrial tachycardia, AV nodal re‐entrant tachycardia, AV re‐entrant tachycardia using an accessory pathway, and ventricular tachycardia with and without ventriculo‐atrial conduction.
Future Directions: Electrical Therapy for Cardiac Tachyarrhythmias
Authors: ZIPES DOUGLAS P. , PRYSTOWSKY ERIC N. , MILES WILLIAM M. , HEGER JAMES J.
Published: July 2006

Directions and research opportunities in basic animal and clinical investigations and in industry that relate to the application and development of electrical devices which control tachyarrhythmias are presented. In basic research, a better understanding of mechanisms responsible for tachyarrhythmias, their onset and methods of termination, would provide increased rationale for selecting a particular therapeutic approach. Knowing the distribution in the heart of applied electrical current when delivered by different types of electrodes placed at different myocardial sites would be helpful. Clinically, we must develop appropriate algorithms to accurately differentiate sinus tachycardia, the various forms of supraventricular tachycardias and ventricular tachycardia. These must be incorporated into future cardioverters and defibrillators. In industry, new sensors, electrodes, expanded telemetry capabilities and implanted microprocessors will aid in creation of a universally applicable generic form of electrical therapy that can be programmed to treat any form of tachycardia.
Effects of Propafenone on Induction and Maintenance of Atrioventricular Nodal Reentrant Tachycardia
Authors: GARCIA‐CIVERA R. , SANJUAN R. , MORELL S. , FERRERO J.A. , MIRALLES L. , LLAVADOR J. , LOPEZ‐MERINO V.
Published: July 2006

Electrophysiologic studies were performed in 10 patients with atrioventriculur (A‐V) nodal reentrant paroxysmal supraventricular tachycardias (PSVT), before and after intravenous administration of propafenone (1.5 mg/kg). All patients utilized an A‐V nodal slow pathway for anterograde conduction and an A‐V nodal fast pathway for retrograde conduction of the reentrant impulse. Propafenone depressed retrograde fast pathway conduction which was manifested by: 1) complete V‐A block at all ventricular paced cycle lengths after propafenone in 3 cases; 2) increase In mean ± SD of ventricular paced cycle length producing V‐A block from <308 ± 37 ms to 432 ± 63 ms in the remaining 7 patients. Nine of the 10 patients had induction of sustained PSVT before propafenone. In 7 of the 9, PSVT could not be induced or sustained after propafenone, reflecting depression of the retrograde fast pathway conduction with either absence of atrial echoes (5 patients) or induction of nonsustained PSVT, with termination occurring after the QRS (2 patients). In 1 patient, single atrial echoes were induced before propafenone but none were noted after the drug. In only 2 patients was a sustained PSVT inducible after propafenone. In conclusion, propafenone inhibited induction of sustained A‐V nodal reentrant PSVT in most patients, reflecting depression of retrograde A‐V nodal fast pathway conduction.
Entrapment of an Atrial Tined Pacemaker Electrode in the Tricuspid Valve—A Case Report
Authors: FÜRSTENBERG STEFAN , BLUHM GÖSTA , OLIN CHRISTIAN
Published: July 2006

A rare complication is described in which an atrial tined pacemaker electrode was trapped in the chordae of the tricuspid valve and could not be removed. A possible method for avoiding this complication is discussed.
Right Ventricular Monophasic Action Potentials in Healthy Young Men
Authors: EDVARDSSON NILS , HIRSCH ISAAC , OLSSON S. BERTIL
Published: July 2006

The right ventricular repolarization phase was studied in 48 healthy men between 20 and 40 years of age. The assessment of the repolarization time included the measurement of ventricular effective refractory periods and monophasic action potentials during constant ventricular stimulation. Computer‐based analysis of the monophasic action potential allowed the duration at 90% and 50% repolarization, the amplitude, the maximal upstroke velocity and the total rise time of the depolarization to be determined. These results may serve as reference values in further studies on ventricular repolarization using the same monophasic action potential recording technique.
The Central Venous Blood Temperature as a Guide for Rate Control in Pacemaker Therapy
Authors: LACZKOVICS AXEL
Published: July 2006

True physiologic pacing is only feasible in patients with heart block and normal sinus rhythm using atrial synchronized pacing. In sick sinus syndrome (SSS) or atrial fibrillation no adequate sensing possibility is present. For these conditions something other than electrical signals must be found to guide rate control. In clinical experiments a thermistor integrated in a bipolar pacing lead was implanted in one of the authors as wall as in a pacemaker patient. Treadmill tests at 3, 6, and 10 km per hour have shown no substantial increase of the central venous temperature (CVT) in the lower effort range; an increase of 0.6–0.75 degrees Celsius (°C) in the medium range; and an increase of 1.35°C in the higher range, respectively. External pacing in the author, or rate variations by programming the VVI, M unit in the patient at rest do not influence CVT. CVT correlates well in the medium‐range group, which mostly reflects the capabilities of the average pacemaker patient. In the higher effort range a delay between rate increase and increase of CVT is noticed. There is no increase in CVT beyond the physiologic variations in the lower effort range.
Spatial Vectorcardiography in the Wolff‐Parkinson‐White Syndrome: Correlation with Epicardial Mapping Findings
Authors: TALWAR KEWAL K. , BLOMSTRÖM PER , EDVARDSSON NILS , WILLIAM‐OLSSON GÖRAN , OLSSON S. BERTIL
Published: July 2006

The spatial vectorcardiograms (VCG) of 13 patients with WPW syndrome due to single accessory pathways were analyzed and correlated with the excitation analysis obtained on epicardial mapping. The azimuth angle of the initial 10 ms cardiac vector was > + 90° (directed right and anteriorly) in patients with a left ventricular free wall; it ranged between 0° to 90° (left and anteriorly) in those with a left or right paraseptal free wall and was ‐ 30° (left and posteriorly) in one patient with a right ventricular free wall location. The elevation angle of the initial 10 and 20 ms cardiac vector was either zero or positive (inferiorly directed) in those with right and left ventricular free wall pathway. Among six patients with a paraseptal location, the elevation angle was negative (superiorly directed) in four and positive in two. Both the patients with a clockwise inscription of a QRS loop in the horizontal plane (HP) had pathways located to the left ventricle. Among the paraseptal group, at surgery, the accessory pathway could not be excised in two in spite of dissection very close to the IV (interventricular) septum. The elevation angle in both these patients was markedly negative (‐45° and ‐62°) in contrast to the other in whom surgical excision was successful. We thus conclude: 1) an azimuth angle of the initial 10 ms vector of more than 90° indicates early activation in the left ventricular free wall and less than 0° on the right ventricular free wall; 2) presence of a negative elevation angle [superiorly directed) of the initial 10 and 20 ms vector suggests a paraseptal location; 3) a markedly negative elevation angle may further indicate that the accessory connection is located very close to, or in, the IV septum.
Anatomopathology of the Normal and Abnormal AV Conduction System
Authors: ROSSI LINO
Published: July 2006

Le système de conduction est responsable des différents troubles du rythme cardiaque qu'ils soient congénitaux ou acquis. La maladie du sinus peut résutler d'une interruption du tissu nodal avec relais par pacemaker inférieur. Le bloc AV peut être d'origine congénitale ou survenir après infarctus grave. Enfin, les voies accessoires de conduction peuvent générer de nombreuses tachycardies supraventriculaires. Les corrélations anatomo‐histologiques permettent l'analyse de beaucoup de ces troubles du rythme.
Physiopathology of Ventricular Tachyarrhythmias
Authors: MOTTÉ G. , LAINE J.F. , SLAMA M. , SEBAG C. , DAVY J.M.
Published: July 2006

Les arythmies ventriculaires peuvent relever de trois mécanismes parfois associés: un automatisme anormal, une activité déclenchée compliquant des postdépolarisations précoces ou tardives; un phénomenène de réntreé par mouvement circulaire ou par réflexion. Ces trois mécanismes fondamentaux ont pu être mis en évidence sur le coeur entier notamment sur les modèles expérimentaux les plus utilisés: l'ischémie myocardique et l'intoxication digitalique. Chez l'homme les arguments en faveur de tel ou tel mécanisme ne sont qu'indirects et reposent essentiellement sur les effets des stimulations. Si aucune certitude n'est actuellement possible, il semble cependant légitime de tirer les conclusions suivantes: (1) Les réntrées sont à I'origine des fibrillations ventriculaires, des exceptionnelles tachycardies ventriculaires de branche à branche, et probablement de la plupart des tachycardies ventriculaires récidivantes chroniques soutenues et aisement inductibles de façon reproductible. (2) Le mécanisme des autres arrythmies ventriculaires reste inconnu. (3) Même lorsque les arrythmies sont en rapport avec des phénomènes de réentrée, les extrasystoles déclenchantes peuvent relever d'un mécanisme focal.
Continuous Ventricular Volume Assessment for Diagnosis and Pacemaker Control
Authors: SALO RODNEY W. , PEDERSON BRIAN D. , OLIVE ARTHUR L. , LINCOLN WILLIAM C. , WALLNER THOMAS G.
Published: July 2006

La mesure du débit systolique par un catheter dans le ventricule droit, utilisant i'impédance intracardiaque, au repos et pendant l'exercise peut être comparée de façon favorable aux mesures obtenues par ventilation à l'acetylene (r = 0.96, n = 13) et par ventriculographie isotopique (r = 0.96, n = 13). Ceci a étéétudié chez un malade de 46 ans en bloc complet. La fréquence de stimulation à l'effort a été déterminée par l'impédance en prenant un algorythme qui maintient un débit systolique constant. Le résultat a montré une augmentation du debit cardiaque de 23% et une baisse du débit systolique de 70%, mesurée à l'effort à une fréquence de 70 cpm.
Pacing for Ventricular Tachycardia
Authors: FISHER JOHN D. , KIM SOO G. , MATOS JEFFREY A. , WASPE LAWRENCE E.
Published: July 2006

Plusieurs problèmes restent à résoudre avant que les stimulateurs puissent jouer un rôle majeur dans le traitement de la tachycardie ventriculaire. Nous citons des exemples pour illustrer quelques difficultés à résoudre. les mécanismes qui contribuent au succès ou à l'échec de la stimulation antitachycardie sont discutés. L'avenir de cette stimulation sera plus assuré dès que ces appareils serent équipés d'un cardioverteur‐défibrillateur de secours.
Clinical Results with Omni‐Orthocor®, an Implantable Antitachycardia Pacing System
Authors: ROTHMAN MARTIN T. , KEEFE JAMES M.
Published: July 2006

L'Omni‐Orthocor 234A et 239A sont deux stimulateurs capables de se synchroniser avec un programmeur externe. Des rafales synchrones ou asynchrones, des extrastimuli synchrones ou une combinaison des 2 peuvent être délivrés. Après reconnaissance d'une tachycardie, le malade ou le médecin peut initier la stimulation, L'Omni‐Orthocor a été implanté chez 69 molades (53 pour tachycordies ventriculaires, 11 pour tachycardies supraventriculaires, 2 pour tachycardies AV par ré‐entrée, 2 pour WPW, et 1 pour tachycardie rétrograde par voie accessoire). Chez 35 patients, la tachycardie a été arrétées en dehors de l'hôpital. Les tachycardies plus résistantes ont été terminées à l'hopital avec 76.3% de succés pour les tachycardies ventriculaires et seulement 50% de succés pour les tachycardies supravenlriculaires. La stimulation en refale a été utilisée chez 75% des patients. Au moins une étude électrophysiologique non‐invasive a été faite chez tous les patients (pour 20 patients elle était la seule indication de l'implant). Le stimuJateur n'était pas impliqué dans la mort subite de 6 patients.
Automatic Implantable Cardioverter‐Defibrillator Structural Characteristics
Authors: MOWER MORTON M. , REID PHILIP R. , WATKINS LEVI , GRIFFITH LAWRENCE S.C. , PLATIA EDWARD V. , BACH STANLEY M. , IMRAN MIR , JUANTEGUY JUAN M. , MIROWSKI M.
Published: July 2006

Il existe différentes options d'appareillage et de techniques chirurgicales pour l'implantation du défibrillateur automatique. Le système peut mime être utilisé mialgré difficultés posées par la présence d'aulres appareils implantés ou par la morphologie du patient. La sensibilité ainsi que l'énergie délivrée peuvent être ajustées selon les besoins des patients. La survie de la pile est suivie de façon non‐invasive, ce qui permet Ie remplacement non‐urgent de l'appareil.
Temporary AVI Pacing by Chest Wall Stimulation
Authors: KERSSCHOT IVO E. , GOETHALS MARC A. , VANAGT EDDY J. , VRINTS CHRIS J. , SNOECK JOZEF P.
Published: July 2006

Temporary atrial pacing (coded AVI pacing) has recently been proposed to assess atrial capture in patients with unipolar dual chamber pacemakers.1–3This pacing mode can usually be achieved by programming the ventricular output to a subthreshold value. In patients with noncomitted bifocal pacemakers, AVI pacing can also be obtained by prolonging the programmed AV delay allowing for spontaneous conduction after atrial capture. However, in patients with prolonged AV conduction and a low aventricular stimuialion threshold, ventricular stimulation cannot be prevented using the forementioned procedures. Using chest wall stimulation, we developed and tested a new method of temporary AVI pacing in patients with noncommitted DDD or DVI pacemakers.
Physiological Versus Single‐Rate Ventricular Pacing: A Double‐Blind Cross‐Over Study
Authors: KRISTENSSON BO‐ERIK , ARNMAN KRISTER , SMEDGÅRD PETER , RYDÉN LARS
Published: July 2006

Previous comparisons of physiological and singie‐rale ventricular pacing are mostly based on open studies. The present investigation was designed to control possible biases of such a study design with the aim to investigate effects of the two pacing modes on maximal and submaximal exercise tolerance and the subjective feeling of well‐being of the patients. Forty‐four patients treated with a trio ventricular synchronous pacemakers for more than 12 months participated in the study. Their pacemakers were randomly programmed to one 3‐week long period of ventricular inhibited and a similar period of atrioventricular synchronous ventricular inhibited pacing. Thereafter, they went through echocardiography, symptom‐limited maximal exercise test and answered a questionnaire on subjective symptoms. The study was blind since neither the patients nor the physician conducting the exercise tests were informed of pacing mode. The mean maximal exercise toleronce increased 14% (p < 0.01) on atrioventricular synchronous pacing. Arterial lactate, respiratory rates and perceived exertion ratings during submaximal levels of exercise were higher on ventricular inhibited pacing, as well as symptoms scored during the two 3‐week periods. A majority of patients improved their functional class during atrioventricular synchronous pacing and preferred the physiological pacing mode.
Implantable Defibrillator Electrode Systems: A Brief Review
Authors: SANTEL DONALD J. , KALLOK MICHAEL J. , TACKER WILLIS A.
Published: July 2006

Since the first report of a defibrillation attempt with an intracurdiac catheter electrode nearly 30 years ago, investigators have developed implantable electrode systems consisting of metal disks, endocardial catheters, and epicardial patches. These early efforts demonstrated the feasibility of low‐energy reversion of ventricular tachyarrhythmias, and also provided some in sight into the mechanisms of fibrillation and defibrillation. This review describes the evolution of implantable defibrillator electrode systems. Early investigators attempted defibrillation with submuscularly implanted metal disks or a disk electrode paired with an endocardiul catheler electrode. Electrode design emphasis turned to transvenous catheter systems with electrodes placed in the right ventricle and right atrium. A more successful configuration placed the proximal electrode in the superior vena cava. In an effort to ensure proper placement of the distal electrode in humans, the catheter was replaced with an epicardial patch. More recently, a combination of electrodes and multiple pulses has substantially reduced the energy required to defibrillate. Effective electrode systems that can convert lethal arrhythmias with a minimum of energy will aid in making implantable cardioverters and defibrillators the therapy of choice in patients at high risk of sudden coronary death.
Activation of the Right Ventricular Apical Electrogram during Ventricular Tachycardia: Suitahility for Synchronizing Intracavitary Cardioversion
Authors: SHARMA ARJUN D. , KLEIN GEORGE J. , MILSTEIN SIMON , MACDONALD ALLENA
Published: July 2006

An infravascular catheter positioned in the right ventricular apex has been used for intracavitary cardioversion in patients with recurrent ventricular tachycardia. We examined the timing of the right ventricular apical electrogram during sinus rhythm and ventricular tachycardia (VT) in order to determine if this signal could be used to synchronize the delivery of a countershock. Sixty‐three distinct morphologies of VT were observed in 33 patients undergoing electrophysiologic testing with programmed stimuiution. Regardless of VT morphology or site of origin, the bipolar right ventricular electrogram always occurred within the peripheral QRS complex during ventricular tachycardia. Relative timing occurred within the QRS rangingfrom the initial 13% of the QHS to the last 12%. When all episodes ofVT were examined, the timing of the right ventricular electrogram did not correlate linearly with the peak of the ECG, but the right ventricular electrogram occurred within 60 ms of the peak ECG in 83% of episodes of ventricular tachycardia. In one case of arrhythniogenic right ventricular dysplasia, the right ventricular electrogram occurred 160 ms after the peak ECG in ventricular tachycardia, a time when delivery of a countershock may have precipitated ventricular fibrillation. Six of these patients underwent cardioversion utilizing an intracavitary catheter and external generator. Acceleration of VT, or conversion to ventricular fibrillation, occurred following two of 27 shocks (7.4%). The right ventricular electrogram occurred the latest within the QRS complex in the two patients who developed acceleration of the tachycardia. Thus, the apical right ventricular electrogram is suitably timed for synchronizing countershock in most patients with VT, thereby enabling the use of a single intracavitary catheter system for sensing and the delivery of the countershock. However, it is necessary to verify appropriate timing of the right ventricular electrogram in each patient for all known morphoiogies of spontaneous VT.
Disseminated Aspergillosis and Pacemaker Endocarditis
Authors: KRAMER LENI , ROJAS‐CORONA ROGELIO R. , SHEFF DANIEL , EISENBERG EDWARD S.
Published: July 2006

Clinical and pathologic findings in a 65‐year old woman with fever of unknown origin are described in this report. Generalized aspergiliosis with endocarditis was demonstrated at autopsy. The patient had no recognized risk factors for the development of fungal infection. A functional transvenous pacemaker lead, inserted 2 years previously, was completely encased in a Jarge infected thrombus and may have been the initial site of infection. Septicemia and endocarditis are rare but well‐described complications of cardiac pacing, and should be considered in the differential diagnosis of fever of unknown origin in patients with pacemakers.
Extreme Intracardiac Coiling of a Transvenous Pacemaker; A Case Report
Authors: KOUBA CRAIG , LIU DEBRA , EVERETT GEORGE , KERBER RICHARD E.
Published: July 2006

We report an unusual complication of transvenous pacing: extreme coiling of a pacemaker catheter, which formed a redundant, twisted loop protruding into the right ventricular outflow tract. This may be a result of “tividdling” (rotation) of the pacemaker generator by the patient and/or inadequate fixation of the catheter at the venous entry site. Careful fixation of the generator to the venous entry site within the subcutaneous pocket may prevent such a complication.
Electrocardiographic Patterns Resulting From Improper Connections of the Right Leg (Ground) Cable
Authors: CASTELLANOS AGUSTIN , SAOUDI NADIR C. , SCHWARTZ ALAN , SODI‐PALLARES DEMETRIO
Published: July 2006

The patterns resulting from improper connections of the right leg (ground) cable to the right arm, left arm, and left leg electrodes (hardly ever discussed in books dealing with electrocardiography) are presented and their genesis is explained. Knowledge about this technical error is important because it: (1) may be misinterpreted os resulting from switching the right arm and left arm cables: and, worse, (2) may not be recognized, which, in patients with abnormal electrocardiograms, can lead to clinically significant errors in interpretation.
Atrioventricular Conduction Abnormalities in Patients Undergoing Isolated Aortic or Mitral Valve Replacement
Authors: KEEFE DEBORAH L. , GRIFFIN JERRY C. , HARRISON DONALD C. , STINSON EDWARD B.
Published: July 2006

Cardiac conduction defects are common in patients with aortic valve disease. Several studies have suggested that the spontaneous occurrence of complete heart block in these patients is related to the extent of calcium deposits in the aortic valve and adjacent structures. No studies have been done to relate the occurrence of complete heart block at the time of valve replacement to predictive factors. We evaluated 102 consecutive patients undergoing isolated aortic valve replacement and 100 patients undergoing isolated mitral valve replacement. Although transient complete heart block was relatively common in each group (17.6% and 13%, respectively), we were not able to identify any factors predictive of its occurrence. There was a very low incidence of late heart block in a follow‐up period of over four years. Thus, the capability for temporary pacing is mandatory in patients undergoing volve replacement. However, transient complete AV block during the perioperative period does not predict late recurrence of AV block and, therefore, prophylactic pacemaker or electrode implantation during or following transient block appears unnecessary.
The Role of Electrophysiologic Studies in the Management of Patients with Unexplained Syncope
Authors: DENES PABLO , EZRI MARILYN D.
Published: July 2006

We evaluated the frequency and type of electrophysiologic abnormalities in an unselected population of consecutive patients with unexplained syncope. Fifty patients were entered in the study; all had 24‐hour dynamic electrocardiographs (Holter) recordings and underwent complete electrophysiological studies. An abnormal electrophysiologic study was found in 74% of the patients. Sinus node abnormality was observed in 30%, abnormal AV node function in 14%, long HV in 10%, block distal to H during rapid atrial pacing in 6%, paroxysmal supraventricular tachycardia in 12%, ventricular tachycardialfibrillation in 8%, and hypersensitive carotid sinus syndrome in 24%. There was no correlation between Holter and electrophysiologic study findings except for the presence of paroxysmal sustained supraventricular tachycardia. Based on clinical, Holter monitoring, and electrophysiologic findings, 38% were treated by antiarrhythmic drugs, 40% received permanent pacemakers, and. 22% were not treated at all. During follow‐up (23 ± 13 months), 9 patients (18%) experienced recurrent syncope or death.
Computed Tomographic Localization of Malposition of Pacing Electrodes: The Value of Cardiovascular Computed Tomography
Authors: FLICKER STEPHANIE , ELDREDGE W. JAY , NAIDECH HOWARD J. , STEINER ROBERT M. , CLARK DONALD L.
Published: July 2006

Three patients with uncertain pacemaker electrode position on plain film radiography were studied with fast cine cardiovascular computed tomography (CT) imaging. The value of this new Technique in determining the position of pacing electrodes is discussed.
Controlled Cryothermal Injury to the AV Node: Feasibility for AV Nodal Modification
Authors: KLEIN GEORGE J. , GUIRAUDON GERARD M. , PERKINS D. GARTH , SHARMA ARJUN D. , JONES DOUGLAS L.
Published: July 2006

Elective subtotal injury to the AV node‐His bundle region may create a negative dromotropic effect to provide a therapeutic advantage in some patients with supraventricular tachycardia without creating complete AV block. We examined the effects of cryosurgery to the AV nodal region, varying temperature and time using a 15 mm circular cryoprobe applied directly to the canine AV node‐His bundle region. Twelve dogs were anesthetized and the heart was exposed through a right thoracotomy. Electrophysiological data obtained included conduction intervals, incremental pacing, and extrastimulus testing. Under inflow occlusion, the cryoprobe was positioned over the AV node‐His bundle region using anatomical landmarks and a single freeze was applied (–15°C to –60°C, 15 to 60 seconds). Dogs were allowed to recover for 1 month, after which time electrophysiological testing was repeated under similar conditions; then the animals were sacrificed. With probe temperatures of –60°C for 15 to 60 seconds, five of six dogs experienced complete heart block with dense fibrosis observed in the AV nodal‐His bundle region. After freezing with higher temperatures, the remaining seven dogs had return of atrioventricular conduction postoperatively with prolongation of AH time observed in five and marked prolongation of the Wenckebach cycle length in three of the five. We conclude that controlled cryothermal injury to the AV node‐His bundle region may be useful to create a desirable negative dromotropic response without creating complete AV block.
Low Energies and Helifix Electrodes in the Successful Ablation of Atrioventricular Conduction
Authors: HOLT P. M. , BOYD E. G. C. A. , CRICK J. C. P. , SOWTON E.
Published: July 2006

High energies delivered via standard pacing catheter electrodes produce permanent atrioventricular conduction block and generate high pressures. We investigated the use of lower energies and an active fixation electrode. Ten patients with refractory supraventricular tachycardias (six with paroxysmal atrial fibrillation, three with dual AV nodal pathways, and one with a concealed accessory atrioventricular pathway) were treated. A 6F Vitatron Helifix electrode was positioned to give the maximum His bundle deflection. Four shocks of only 50 joules each were delivered at 1‐minute intervals. Long‐term follow‐up showed that seven patients (70%) had persistent complete heart block and two had atrial fibrillation with slower ventricular rates. Nine patients (90%) were symptom‐free without antiarrhythmic therapy. Permanent pacemakers were implanted in eight patients. There were no complications resulting from the procedure. Transvenous ablation of atrioventricular conduction can be safely achieved using a Vitatron Helifix eleclrode and much lower energy values than have been previously employed.
Pacemaker Diagnostic Diagrams
Authors: OLSON W. H. , McCONNELL M. V. , SAH R. L. , BECK R. C. , SUTTON R.
Published: July 2006

Dual‐chamber pacemakers interact with cardiac rhythms in complex ways. The resultant surface electrocardiograms (ECGs) are often very difficult to interpret. A simple and automatic diagnostic diagram is described that graphically illustrates pacemaker‐heart interactions. Pacemaker operation is explained by a continuous series of lines and symbols that interconnect any sequence of paced and sensed events in both chambers. Fixed, programmable, and adaptive pacemaker timing intervals are all shown in a simple format. The pacemaker diagnostic diagram is plotted directly below the ECG to help users interpret the paced cardiac rhythm. The pacemaker diagnostic diagram is generated by software in a pacemaker programmer from: (1) telemetered real‐time event markers; (2) fixed and programmable timing parameters (lower rate, AV interval, etc.); (3) pacemaker conditional logic. If this computer analysis of the telemetered event markers is not consistent with normal pacemaker operation, a specific error‐message is printed. The pacemaker diagnostic diagram should be useful for instruction, pacemaker follow‐up, and troubleshooting.
Removal of Fractured Pacemaker Electrode Tip Using Dotter Basket
Authors: RAMSDALE DAVID R. , ARUMUGAM NACHIAPPAN , PIDGEON JOHN W.
Published: July 2006

During attempted removal of an infected permanent pacemaker syslem, the electrode fractured. leaving the tined tip embedded in the wall of the left subclavian vein. The eleclrode tip was successfully removed using a Dotter basket retrieval kit.
A Time‐Related Study of the Hemodynamic Benefit of Atrioventricular Synchronous Pacing Evaluated by Doppler Echocardiography
Authors: FAERESTRAND SVEIN , OHM OLE‐JØRGEN
Published: July 2006

We have used Doppler echocardiography to estimate the stroke volume (SV) in a study of 13 patients equipped with DDD pacemakers. SV was measured both during DDD and WI pacing after observation times of 1,3, 6, and 12 months of DDD pacing. SV was also measured at seven atrioventricular (AV) intervals (75–250 ms) in the search for optimal AV intervals. Mitral flow velocity was investigated to see if DDD pacing resulted in synchronous atrial contraction, and if mitral insufficiency existed at any of the pacing modes. Compared with the VVI mode, DDD pacing resulted in a mean increase in SV of 21 ± 2% for the four observation periods. Two patients with severe left ventricular failure had no significanl increase in SV during DDD vs VVI pacing. In each patient, an optimal AV inlerval ranging between 100–250 ms for the SV was found. Velocity profiles of mitral flow showed synchronous atrial contraction during DDD pacing, but not during VVI pacing. Mitral insufficiency was not seen in any pacing mode. DDD pacing resulted in a reduction in SV during the first 6 months, and was constant thereafter. Doppler echocardiography can be used repeatedly to evaluate the hemodynamic response of DDD pacing vs VVI pacing, and to find which AV interval gives the highest SV in the individual patient. Our study further shows that the hemodynamic benefit of DDD pacing is present after short‐term as well as after long‐term DDD pacing.
Internal Cardiac Defibrillation Threshold: Effects of Acute Ischemia
Authors: JONES DOUGLAS L. , SOHLA ANAND , KLEIN GEORGE J.
Published: July 2006

The influence of myocardial ischemia on defibrillation success was studied using two different lead orientations in halothane‐anesthetized pigs. Ischemia was induced by ligating the left anterior descending artery in its distal third. Controls had loosely tied ligatures placed around the artery at the same site. Ventricular fibrillation was induced by electrical stimulation 30 minutes after coronary artery ligation. Defibrillation used a single truncated pulse of approximately 6 ms duration passed to either: (1) a transvenous electrode catheter (Medtronic, 6880) with the cathode in the apex of the right ventricle and the anode in the superior vena cava‐atrial junction region. or (21) the cathode in the apex of the right ventricle and a mesh plaque on the epicardium of the basal lateral left ventricle as anode. Ten seconds after the onset of ventricular fibrillation, defibrillation was attempted with increasing incremental energies until defibrillation was achieved. Fibrillation episodes were repeated at 15‐minute intervals until the minimum first shock was successful in defibrillating the animal (i.e., defibrillation threshold).

The number of animals successfully defibrillated with a minimum energy above or below 30 J was not different between normal and ischemic animals for either electrode configuration (i.e., 3 out of 20 vs 1 out of 13 for the catheter and 5 out of 6 vs 6 out of 7 for the epicardial plaque, respectively). Also, the cumulative percent success as a function of defibrillation energy was similar in both the normal and ischemic groups. There was a significant reduction in the minimum energy necessary for defibrillation when passing current between the right ventricular apex and the left ventricular epicardial plaque.

The present results indicate that, despite differences in lead orientations, acute ischemia in the anesthetized pig does not appear to influence defibrillation success.