bluuebunny/crossref_metadata_2025 huggingface dataset:
Design‐Dependent Cross‐Talk in a Second Generation DDD Pacemaker
Authors: BEAVER BARNEY B. , MALONEY JAMES D. , CASTLE LON W. , MORANT VICTOR A. , KEEFE JAMES M. , CHING ELIZABETH
Published: July 2006

. A unique mechanism of “cross‐talk” has recently been described in the Gemini 4J5A DDD pacemaker in which cross‐inhibition of the ventricular output stimulus may occur in the early Gemini 415A models which were manufactured with dual anodal rings interconnected by a wire. The Gemini 415A units with dual anodal rings were implanted under investigational protocol in 53 patients from September 1982 to August 1984. To date, cross‐talk has been discovered in six patients during clinical follow‐up, manifesting as inappropriate ventricular inhibition. Syncope was documented in one patient. Non‐Cordis atrial and ventricular leads were present in all six patients and five patients had at least one chronic lead. Cross‐talk was neither evident nor provokable in Gemini 415A units which had compatible Cordis lead systems. Reduction of the atrial output and/or the ventricular sensitivity prevented cross‐inhibition in three patients. Cross‐talk persisted in three patients despite programming to the lowest atrial output and/or ventricular sensitivity parameters. Cross‐talk, spontaneous or provoked, has not occurred in 36 patients having currently designed 415A pulse generators manufactured with a single anodal ring in the ventricular connector channel. We conclude that: (1) this unique form of cross‐talk is “design‐dependent” and occurs only in Gemini 415As with dual interconnected anodal rings and cannot occur in 415As manufactured with a single anodal ring; (2) this form of cross‐talk has occurred only in 415As with non‐Cordis leads and appears to be a time dependent development; (3) reduction of the atrial output or use of pacing modes without atrial pacing or ventricular sensing can prevent cross‐talk; (4) patients with Gemini 415As having dual anodal rings, which can be identified radiographically. are at risk for this design‐dependent cross‐talk and merit close observation.
Wide QRS Tachycardia Due to AV Nodal Reentry and a “Bystander” Bypass Tract with Slow Conduction Properties
Authors: DENG ZHAOWEN , GANG ELI S. , ROSENTHAL MARK E. , OSERAN DANIEL , MANDEL WILLIAM J. , PETER THOMAS
Published: July 2006

. An unusual mechanism for recurrent, wide QRS complex supraventricular tachycardia is described in this report. A 25‐year‐old man with normal PR and QRS intervals during sinus rhythm was shown to have preexcitation with a left bundle branch block pattern during tachycardia and during atrial pacing. Electrophysiologic studies demonstrated slow and decremental conduction properties in an accessory “bystander” AV pathway utilized for antegrade conduction during AV nodal reciprocating tachycardia. The differential diagnosis of this tachycardia is discussed in detail.
Asymptomatic Pulmonary Embolism Following Pacemaker Implantation
Authors: SEEGER WALTER , SCHERER KLAUS
Published: July 2006

The aim of this prospective study was to investigate the incidence of pulmonary embolism after pacemaker implantation, and to assess the benefits, if any, of postoperative prophylactic heparin therapy. Twenty of 40 patients were given low‐dose heparin therapy; the remaining 20 patients were the control group and were not treated. Assignment to one of these groups was made alternately, in chronological order according to the time of implantation. Only tined leads with silicone insulation were used. All patients were mobilized on their first postoperative day. Pulmonary scintigraphy was performed before implanlation, two weeks after implanlation and again 12 months later. A pulmonary embolism was defined as evidence of new perfusion defects after implantation. There were no such defects in the group treated with heparin; the control group (20 patients) had three cases of perfusion defects within a 14‐day postoperative period. Twelve months later, no further perfusion defects were observed in any patient. Thus, our study revealed a 15% incidence of asymptomatic pulmonary embolism following pacemaker implantation in patients not given prophylactic heparin therapy.
Permanent Interatrial Septal Pacing: Feasibility and Advantages
Authors: STIRBYS PETRAS
Published: July 2006

One hundred eighty‐nine implanted atrial pacing leads have been analyzed. A double screw‐in active fixation lead was attached to the interatrial septum in eight patients and a J lead in one patient. The right atrial appendage was the site used in the 97 other patients with a double screw‐in lead; a J‐shaped lead ivos used in three and an anchored (active fixation) lead in the remaining 80 patients. Though pacing from the interatrial septum has different characteristics of lead stability, it offers a number of advantages over right atrial appendage stimulation.
Prolonged Sinus Arrest Complicating a Thrombotic Stroke
Authors: KUSHNER MARK , PETERS ROBERT W.
Published: July 2006

A 56‐year‐old man developed sinus node dysfunction culminating in 27 seconds of asystole during a thrombotic stroke. Bradyarrhythmias resolved over a period of 96 hours, at which time sinus node recovery times were normal. Sinus node dysfunction has not recurred during the two years of follow‐up. We suggest that cardiac rhythm be closely monitored in acute stroke patients.
Procainamide‐Induced Incessant Supraventricular Tachycardia in the Wolff‐Parkinson‐White Syndrome
Authors: ELDAR MICHAEL , RUDER MICHAEL A. , DAVIS JESSE C. , ABBOTT JOSEPH A. , SEGER JOHN , GRIFFIN JERRY C. , SCHEINMAN MELVIN M.
Published: July 2006

A patient with the Wolff‐Parkinson‐While syndrome presented with incessant orthodromic atrioventricular tachycardia following initiation of procainamide therapy. This finding was repeatedly documented both clinically as well as during electrophysiologic testing. Escape atrial complexes, which occurred following junctional premature complexes, failed to initiate tachycardia in the control state but tachycardia was always reinitiated by an identical escape sequence after procainamide. In addition, the tachycardia persisted and was repeatedly spontaneously reinitiated for prolonged periods after procainamide. The pro‐arrhythmic effects of procainamide may be explained on the basis of both its vagolytic action on the atrioventricular node as well as by prolongation of refractoriness in the accessory pathway. These observations add to the literature on pro‐arrhythmic effects of commonly used antiarrhythmic drugs.
Electrocardiographic Response of Digoxin‐Toxic Fascicular Tachycardia to Fab Fragments: Implications for Tachycardia Mechanism
Authors: WIELAND JEFFREY M. , MARCHLINSKI FRANCIS E.
Published: July 2006

The electrocardiographic response of digoxin‐induced fascicular tachycardia to Fab fragments was evaluated in two patients. In addition, we documented the response of the fascicular tachycardia to spontaneous premature ventricular depolarizations during different tachycardia rates, the response to a nonsustained episode of ventricular tachycardia, and the mode of spontaneous initiation and termination of short‐lived episodes of the tachycardia during the treatment process. The following findings were noted: (1) slowing of the tachycardia in response to Fab administration; (2) change in the morphologic characteristics of the tachycardia from multiform to uniform; (3) resetting of the tachycardia by spontaneous premature ventricular depolarization with the return cycle equal to the observed tachycardia cycle length; (4) acceleration of the tachycardia in response to five beats of a faster nonsustained ventricular tachycardia; and (5) initiation and termination of the tachycardia, both by spontaneously occurring premature ventricular depolarizations and in the absence of premature ventricular depolarizations. Both tachycardias resolved completely within 20 and 40 minutes, respectively, of Fab administration. We conclude that Fab administration can promptly resolve fascicular tachycardias precipitated by digoxin toxicity and that the observed electrocardiographic phenomena strongly suggest triggered activity as the electrophysiologic mechanism of fascicular tachycardia in man.
Failure to Sense P Waves During DDD Pacing
Authors: VAN MECHELEN ROB , 'T HART CONNIE , DE BOER HANS
Published: July 2006

ECG tracings of three patients in whom AV universal (DDD) pacemakers were implanted intermittently demonstrated dropped P waves. In one patient, true atrial undersensing was present; in the others, sensing of the atrial electrode was appropriate, but sensing of sinus P waves was intermittently blocked by normal pacemaker operation. In this report we discuss the electrocardiographic diagnosis of atrial undersensing in order to avoid unnecessary reinterventions.
Holter‐Monitored Heart Rhythm During Atrioventricular Synchronous and Fixed‐Rate Ventricular Pacing
Authors: KRISTENSSON BO‐ERIK , KARLSSON ÖSTEN , RYDÉN LARS
Published: July 2006

The purpose of this investigation was to study rate variability during normal everyday activities among physiologically paced patients. A comparison of the spontaneous occurrence of arrhythmias with ventricular inhibited pacing was also mode. VDD pacemakers in 44 patients were randomly programmed to three‐week long periods of VVI (70 bpm) or VDD (back‐up rate 40‐50 bpm, upper rote 125–150 bpm) pacing, respectively. A Holter ECG was recorded during the last 24 hours of each period. Although the total number of QRS complexes was similar in the two pacing modes (4.3 × 106/24 hours), the rate span was extensively utilized during VDD pacing. During VDD pacing, only five patients of 39 with a programmed upper rate of 150 bpm reached this limit, while one of five with 125 bpm reached that rate. Occasional episodes of pacing at the back‐up rate of 40 or 50 bpm were recorded in 33 patients. Episodes of asymptomatic rhythm disturbances were recorded in both pacing modes. No significant differences existed as regards ventricular tachyarrhythmias between the two modes of pacing and it did not seem that the incidence was higher than could be expected in a patient population of the present age. Since severe AV block does not permit conduction of atrial impulses during VVI pacing, no direct comparison between the two pacing modes can be made concerning atrial tachyarrhythmias. Only one episode of pacemaker‐mediated SVT was found, and this was unsymptomatic.
Combination Antiarrhythmic Drug Therapy For Ventricular Tachyarrhythmias
Authors: GREENSPAN ALLAN M. , SPIELMAN SCOTT R. , HOROWITZ LEONARD N.
Published: July 2006

New antiarrhythmic drug regimens are constantly being sought because of the relatively low efficacy rates of standard antiarrhythmic agents in preventing induction of ventricular tachyarrhylhmias; the application of these agents is also limited due to serious or debilitating side‐effects. The combination of two antiarrhythmic agents with complimentary electrophysiologic activities and differing toxicities might offer significant advantages in overcoming the drawbacks of standard antiarrhythmic drug therapy. A knowledge of the pharmacodynamics of the major classes of antiarrhythmic agents will allow informed choices of drugs for use in combination therapy. Judging antiarrhythmic drug efficacy is a complex problem, requiring an understanding of (he influence of the arrhythmia monitoring technique. arrhythmia morphology and the response to previous drugs on drug efficacy rates, so that accurate comparisons of drug effectiveness can be made among different agents or combinations. A number of combination therapies have been tested for suppression of complex ventricular ectopy, nonsustained ventricular tachycardia and sustained ventricular tachycardia and ventricular fibrillation. The most successful combinations have been those using class IA and IB agents and class IA and II agents. In general, these combinations tend to show higher efficacy rates in suppressing all forms of ventricular ectopy and ventricular tachyarrhythmias, and usually have a lower incidence of toxic side‐effects compared with individual agents alone. On the basis of these initial results, it seems warranted to perform further studies to explore these combinations in larger populations and to test new combinations developed on the basis of pharmacodynamic principles.
Alternating Left and Right Bundle Branch Block Aberration of Atrial Extrasystoles in Bigeminal Rhythm
Authors: ORETO GIUSEPPE , LUZZA FRANCESCO , LAPRESA VINCENZO , SATULLO GAETANO , SCHAMROTH LEO
Published: July 2006

We report two cases of atrial extrasystolic bigeminy manifesting with alternating right and left bundle branch block aberration. The manifestation is explained on the basis of cycle‐dependent variations of the bundle branch refractory period with alternate resetting of bundle branch refractoriness.
Implantation of the Automatic Implantable Cardioverter Defibrillator (AICD): Practical Aspects
Authors: CANNOM DAVID S. , WINKLE ROGER A.
Published: July 2006

Most patients who are resuscitated from an episode of sudden cardiac death or one of sustained ventricular tachycardia (VT) can now be treated using serial electrophysiologic testing as a guide to drug therapy. Recurrence rates are low if an antiarrhythmic regimen can be found which prevents induction of VT. Patients failing serial drug testing have a high recurrence rate (approximately 50%/year). Most clinicians now refer such patients for either experimental antiarrhythmic therapy or electrical intervention. The most promising of the electrical interventions (including tachycardia converting pacemakers and intraoperative mapping)has been the automatic implantable cardioverter defibrillator (AICD). Only recently has the AICD been released from investigative status by the Food and Drug Administration. It can be implanted safely and with favorable clinical outcome if the techniques of implantation are well understood and used often. The text incorporates the authors' experience in implanting nearly 200 devices and is intended as a practical guide to the use of the AICD.
Classic and Concealed Entrainment of Typical and Atypical Atrial Flutter
Authors: BECKMAN KAREN , HUANG‐TA‐LIN  , KRAFCHEK JACK , WYNDHAM CHRISTOPHER R. C.
Published: July 2006

Classic and concealed entrainment was demonstrated in a patient with spontaneous typical atrial flutter and pacing induced atypical atrial flutter. The form of enirainment manifested depended on the site of pacing and the direction of tachycardia as determined by endocardial mapping.
QT Prolongation and Torsade de Pointes Ventricular Tachycardia Produced by Ketanserin
Authors: ALDARIZ ANTONIO E. , ROMERO HORACIO , BARONI MARTA , BAGLIVO HUGO , ESPER RICARDO J.
Published: July 2006

A 65‐year‐old man with arterial hypertension received oral treatment with Ketanserin, a new drug, during a period of five months. He developed marked QT interval prolongation and have several Stokes‐Adams attacks. A Holter recording obtained during one of these episodes showed torsade de pointes ventricular tachycardia. The arrhythmias occurred during maximum QT interval prolongation, The correlation between Ketanserin and QT interval prolongation was evaluated by using several Holter studies during administration and withdrawal of the drug. The effect of Ketanserin on the QTc interval was analyzed retrospectively in six patients who had been taking the drug orally. Following a period of four to eight months, the QTc interval was prolonged by the drug (5 to 31%, mean 17%) in five patients. We conclude that torsade de pointes is a potential hazard of long‐term treatment with Ketanserin.
Effects of Different Modes of Stimulation on the Morphology of the First QRS Complex Following Pacing During Digitalis‐Induced Ventricular Tachycardia: Observations in the Conscious Dog With Chronic Complete Atrioventricular Block
Authors: GORGELS ANTON P.M. , DE WIT BRAM , BEEKMAN HENRIETTE D.M. , DASSEN WILLEM R.M. , WELLENS HEIN J.J.
Published: July 2006

During digitalis‐induced, sustained, monomorphic ventricular tachycardia, programmed electrical stimulation was performed and the effect on the first post‐pacing QRS morphology was determined. Ventricular tachycardia was induced in nine conscious dogs with chronic complete atrioventricular block by administering digoxin i.v. 0.1 mg/kg given in 1‐½ hour. Spontaneous ventricular tachycardia most frequently had a right bundle branch block morphology and an extreme left axis suggesting an origin in the apex of the left ventricle. Less frequently, a left bundle branch block‐like configuration with an intermediate axis was observed, compatible with an origin in the basal part of the right ventricle. Following pacing close to one of these predilection sites, the first post‐pacing QRS morphology suggested an origin close to the site of stimulation. Pacing distant from these predilection sites resulted in fusion complexes between electrical activaion from these predilection sites and the stimulation site. The amount of fusion depended on interstimulus interval and the number of stimuli. Long interstimulus intervals and few stimuli induced a QRS complex similar to that of the spontaneous tachycardia. The faster and longer the stimulation train, the more the QRS complex became similar to the paced QRS complex. Similar findings were also observed on decreasing the last paced interval only. Our findings suggest that triggered activity is the underlying mechanism for the first post‐pacing QRS complex. QRS configuration and the relation between the R‐R interval and QRS configuration during tachycardia suggest that triggered activity is also the mechanism for the spontaneously occurring ventricular tachycardia during digitalis intoxication. These observations may have important clinical implications.
Trends in Pacemakers Which Physiologically Increase Rate: DDD and Rate Responsive
Authors: FEARNOT NEAL E. , SMITH HEIDI J.
Published: July 2006

Exercise (rate) responsive pacemakers benefit patients by providing increased cardiac output when needed and permitting lower rate during rest. This paper briefly reviews trends in reported studies on rate responsive pacemakers. For patients with reliable atrial rhythms, atrial‐triggered pacemakers (DDD) provide physiological ventricular rates unless complications arise. At low rates, A‐V synchrony benefits patients with refractory cardiac decompensation; however, in patients with healthy myocardiums, achieving higher pacing rates is more significant than maintaining synchrony. If atrial rhythms are unreliable, an alternative sensor for determining pacing rate is indicated. Pacemakers that respond to changes in right ventricular blood temperature, respiratory rate, QT interval, body vibration (motion), and pH have been implanted in humans. Clinical evaluations have shown that increased pacing rate leads to increased exercise tolerance and cardiac output when needed, independent of the sensor type (DDD, QT, respiratory rate, etc.). The effectiveness of any sensor type to increase pacing rate appropriately requires reliable sensors that respond specifically to the need for increased pacing rate. Sensors for stroke volume, venous oxygen saturation, right atrial or ventricular pressure and catecholamines are also under preclinical investigation. The availability of a reliable, long‐term sensor is a key limitation to several techniques including pH. stroke volume, oxygen saturation, pressure, and catecholamines. Sensor technology and clinical effectiveness are the keys to rate responsive pacing.
A Central Venous Temperature Sensing Lead
Authors: BAKER ROSS G. , PHILLIPS RICHARD E. , FREY MICHAEL L. , CALEEE RICHARD V.
Published: July 2006

Pacemaker rate responsiveness derived from changing central venous blood temperature requires the development of sensor leads that are stable and reliable. The relevant characteristics of one such design are described. Temperature response time, data acquisition time, temperature sensitivity, and long‐term sensor shunt impedance have been studied both in vitro and in vivo. These parameters are analyzed with respect to the intrinsic temperature signal and to pacemaker implementation problems.
Measurement of Right Ventricular Blood Temperature During Exercise as a Means of Rate Control in Physiological Pacemakers
Authors: ALT E. , HIRGSTETTER C. , HEINZ M. , THERES H.
Published: July 2006

Several biological parameters have been suggested for rate control in physiological pacemakers in the past. Up to now, measurements of central venous blood temperature have been mostly done on dogs. We studied central venous blood temperature and heart rate in 14 healthy volunteers under conditions of treadmill and bicycle exercise with different workloads. A custom made 5F lead with a thermistor incorporated near the tip was placed at the right ventricle under fluoroscopic control. Temperature was recorded with an accuracy of 1/100°C on a digital memory device at a sampling rate of 5–10 s. We found the increase in blood temperature to be not only a function of absolute workloads but also a function of the individual's maximum exercise tolerance. Independent of the absolute increase in heart rate and temperature at a given workload, the individual's relation of increase in temperature and heart rate was found to be highly correlating (r = 0.9095). At a load of 100 W, we found a mean increase in heart rate of 52 beats and of temperature of 0.57°C, at 750 W of 74 beats/min and 0.84°C. During, as well as after, the exercise, heart rate and temperature have a parallel course. According to our data, control of physiological pacemakers by means of central venous blood temperature is possible.
Characteristics and Clinical Effects of Myopotential Signals in a Unipolar DDD Pacemaker Population
Authors: ZIMMERN SAMUEL H. , CLARK MARTHA F. , AUSTIN W. KENNETH , FEDOR JOHN M. , GALLAGHER JOHN J. , SVENSON ROBERT H. , DUNCAN JAMES L.
Published: July 2006

Myopotential signals were recorded from atrial and ventricular leads during isometric exercise in 25 patients who had chronically implanted dual chamber pacemakers using the electrogram telemetry capability of the pacemakers. Average electrogram amplitude on the atrial channel was 0.92 mV (range 0.3 to 1.9) and on the ventricular channel was 0.98 mV (range 0.3 to 2.2); the difference was not significant. There was a strong correlation (R = 0.82) between the amplitude of myopotentials on the atrial and ventricular leads for individual patients. Myopotential sensing caused ventricular output inhibition in two patients (8%) and ventricular tracking in sixteen patients (64%). Pacemaker reprogramming abolished ventricular myopotential inhibition in all patients and stopped ventricular myopotential tracking in seven patients. We conclude that myopotentials can be analyzed and their effects ameliorated by a multiprogrammable pacemaker with electrogram telemetry capability.
What Is the Most Appropriate Stimulation Mode in Patients with Sinus Node Dysfunction?
Authors: MARKEWITZ ANDREAS , SCHAD NIKOLAUS , HEMMER WOLFGANG , BERNHEIM CHRISTOPH , CIAVOLELLA MASSIMO , WEINHOLD CHRISTIAN
Published: July 2006

Sinus node disease (SND) has caused many controversies about the appropriate stimulation mode. We compared the advantages and disadvantages of VVI, AAI, DDD, and DDI mode. In an additional study, left ventricular function at rest [R] and during exercise [E] was investigated in dual chamber and ventricular stimulation mode with a stimulation rate of 70 ppm [R] and 110 ppm [E]. A total of 223 patients [pts] was investigated (67 AAI, 87 VVI, 69 DDI]. Hemodynamic disadvantages in VVI mode resulted in a 55% actuarial incidence of atrial fibrillation after five years. In AAI mode, we found another 25% complication rate due to impaired AV conduction [n = 9] or a bradyarrhythmia [n = 6] with slow ventricular response. DDD mode implies the possibility of sustaining a pacemaker mediated tachycardia. Single ventricular stimulation with a high stimulation rate (110 ppm] under E showed a worse left ventricular performance as compared to dual chamber stimulation. DDI mode shows none of the aforementioned disadvantages. To sum it up: Until a dual chamber rate responsive pacemaker becomes available, the DDI mode represents the best stimulation mode for patients with a SND.
Importance of Atrial Electrophysiology in the Work‐up of Cerebral Ischemic Attacks
Authors: ATTUEL P. , RANCUREL G. , DELGATTE B. , COLCHER E. , CHAZOULLIERES PH. , FRIOCOURT P. , MUGICA J. , COUMEL PH.
Published: July 2006

Recent data suggest that a large proportion of ischemic strokes are due to embolic phenomena from the heart. Atrial fibrillation appears to be one of the principal causes of embolization. If electrophysiologic parameters are considered as determining factors, the existence of atrial hypervulnerability in patients with embolic strokes is significant, when arrhythmia has been excluded as an etiology. This study suggests that an aggressive approach to early diagnosis and management through electrophysiologic studies might aid in preventing future neurologic attacks.
The Impact of Pending Technologies on a Universal Connector Standard
Authors: DORING JOHN , FLINK ROBERT
Published: July 2006

Standardization of pacemaker lead connectors promises to aid clinical practice. In the past, clinician concern for continued innovation has moderated calls for standardization. Today, connector standards are under consideration in the International Pacemaker Standards Working Group. Reliability, compatibility with existing implanted leads, and interchangeability between bipolar and unipolar leads are among the clinical concerns the standard process must address. Pending technologies will limit the future utility of the standard or be impeded by its regulatory imposition. Well‐informed decisionmaking in the standards process combined with a practical appraisal of the impact on future technology will help assure that, in balance, a net benefit to clinical practice results from connector standardization. The issues warrant broad review and discussion among individuals and groups interested in pacing.
The Clinical Utility of Pacemaker Follow‐up Visits
Authors: MUGICA JACQUES , HENRY L. , ROLLET MAURICE , PODEUR HENRI , HAQUIN G.
Published: July 2006

Because of the increased complexity of modern pacemakers, pacemaker follow‐up visits in specialized centers become more and more indispensable. In this study, the results of 15,000 outpatient visits to the cardiac pacing center between the years 1983–1985 are presented. In most cases (92.8%), verification of normal function was made; however, mandatory reprogramming was required in 1.2%, and hospitalization for various reasons was required in 6% of visits. Careful outpatient monitoring of pacemakers is therefore very important for detecting early or late pacemaker complications.
Survival and Mortality in 3,701 Pacemaker Patients: Arguments in Favor of Pacemaker Reuse
Authors: MUGICA JACQUES , DUCONGE ROBERT , HENRY L.
Published: July 2006

This study analyzed the results of 3,701 patients implanted with cardiac pacemakers at the Centre Chirurgical du Val d'Or between 1976 and 1981. Two pacemaker populations were compared; those having a new pacemaker and (hose implanted with a reused pacemaker. There were no statistically significant differences between the two groups, either in terms of indications for implantation or in terms of actuarial survival of patients. In addition, there was no significant change in survival of the pulse generator. The reutilization of pacemakers appeared to be in no way detrimental to patients.
Is Reuse Financially Worthwhile?
Authors: MYERS GEORGE H.
Published: July 2006

The issue of pacemaker reuse is a complicated one. While reuse of other medical devices is feasible, the reuse of implanted pacemakers is dependent upon multiple variables. Among these are battery life, availability of units, and costs of refurbishment When considered using current cost codes, the savings associated with pacemaker reuse are generally negligible and generally do not encourage widespread adoption of this practice.
Internal Ventricular Defibrillation with Sequential Pulse Countershock in Pigs: Comparison with Single Pulses and Effects of Pulse Separation
Authors: JONES DOUGLAS L. , SOHLA ANAND , BOURLAND JOE D. , TACKER WILLIS A. , KALLOK MICHAEL J. , KLEIN GEORGE J.
Published: July 2006

We compared single to sequential pulse shocks with different pulse separations on internal cardiac defibrillation by using a catheter and plaque electrodes in open‐chest halothane‐anesthetized pigs. Ten seconds after fibrillation onset, defibrillation was attempted using trapezoidal pulses of 65% tilt, approximately 5 ms duration and fixed outputs from 1.0 to 50 joules (J). With single pulses, minimum defibrillation energy for the catheter alone was 2.4 ± 0.3 J/kg (mean ± standard error) and 2.1 ± 0.2 J/kg for the catheter tip to plaque configuration. With sequential pulse shocks, the first pulse delivered via the catheter and the second pulse from the catheter tip to the plaque electrode, the energy necessary for defibrillation was dependent on the separation time between the two pulses (2.0 ± 0.2, 1.5 ± 0.2, 0.9 ± 0.1, 1.3 ± 0.3, 0.6 ± 0.2, and 1.2 ± 0.2 J/kg at 100, 10, 1, 0.5, 0.2, and 0.1 ms, respectively). Further, at the 0.2 ms separation, 100% of the animals could be defibrillated with less than 2.0 J/kg (35 J total). We conclude that sequential pulse defibrillation provides a significant improvement over single pulse defibrillation. The optimum separation between the sequential pulses in this study was 0.2 ms.
Benign X‐Linked (Emery‐Dreifuss) Muscular Dystrophy is not Benign
Authors: WYSE D. G. , NATH F. C. , BROWNELL A. K. W.
Published: July 2006

Emery‐Dreifuss muscular dystrophy is sometimes referred to as benign X‐linked muscular dystrophy. We present two young patients ivith this disorder who had severe cardiovascular complications including: conduction disease, major thromboembolic events, valvular dysfunction with congestive cardiac failure, ventricular tachyarrhythmias, and sudden cardiac death. Of these cardiac problems, only conduction disease has been previously emphasized. This form of muscular dystrophy is not benign—it has malignant cardiac manifestations.
Muscle Noise and Interference Behavior in Pacemakers: A Comparative Study
Authors: IRNICH W.
Published: July 2006

Inhibition of VVI pacemakers by muscle noise, though known since 1972, has attracted increased interest in recent years. More sensitive dual chamber atrial synchronized pacemakers have proved to be more susceptible to interference and will further enhance the effort at improving pacemaker resistance to interference of ail kinds. To study the reaction of 16 pacemakers of 10 different manufacturers with respect to muscle noise, we stored a noisy episode on a 16‐second endless loop tape. Each pacemaker was subjected to an identical muscle noise signal, with amplitude varied to reach the response threshold. The results are: (J) The range of muscle noise thresholds consists of more than one decade, varying from 0.4 mV to 4.6 mV. (2) Only 4 of 16 pacemakers remained unaffected if a noise signal of 3 mV maximum is assumed. (3) In 11 out of 16 pacemakers, the threshold amplitude for muscle noise is lower than that for intracardiac electrographic signals which can be explained by a sensitizing mechanism caused by noise. (4) Five pacemakers were so sensitive that even a sensitivity setting of 4 mV would not reject muscle noise. (5) Filtering muscle noise, 50‐Hz signals, and intracardiac electrograms with a 12 dB filter of variable upper cut‐off frequency revealed that heart signals are always attenuated more than interference signals.
Electrical Stimulation of the Spinal Cord: A Critical Review
Authors: SELIGMAN LEE J.
Published: July 2006

Electrical stimulation of the spinal cord has been practiced as a therapy by the medical community for nearly two decades. Despite optimistic expectations, interest and participation in spinal cord stimulation have been moderate. Considering the declining number, worldwide, of papers dealing with this therapeutic method in humans, it appears that, following a surge of interest in the late 1970s, the technique is losing adherents (or, at best, progressing slowly.) Over the same period there has been rapid growth of much new clinical technology, particularly cardiac pacing. The reasons for this slow progress lie in several areas, including technology and neuroanatomy. It remains for the neurological research scientist to identify more precise and elective approaches to central neural therapy, and for the engineer to find better methods of directing stimulating energies to specific target tissues. Until such breakthroughs are realized, implanting physicians can only continue to analyze patient data in an attempt to refine the techniques that are possible today.
Sensory Thalamic Neurostimulation for Chronic Pain
Authors: SIEGFRIED JEAN
Published: July 2006

Among all kinds of pain, deaffer‐entation pain is the most physically and mentally debilitative; this affliction is often resistant to medications and to the effects of ablative neurosurgical procedures. Since the introduction of neurostimulation as a method of treatment of pain, stimulation of the sensory thalamic relay nucleus has been proven effective in the majority of cases of patients suffering from deafferentation pain. The method used for thalamic stimulation and the results obtained in a series of 89 patients treated from October 1978 to October 1985 will be presented. Postherpetic trigeminal pain has the best chance of responding to thalamic stimulation with a long‐term success rate of 80%. This is also true for anesthesia dolorosa of any origin (after ablative surgery, nerve lesions, paraplegia). In the opposite, only 50% of patients with either brachial plexus avulsion or thalamic pain syndrome will have a significant benefit from thalamic stimulation. It would appear that the success of thalamic stimulation in these disorders may be dependent upon the extent of the central lesion from the periphery up to the thalamic regions (dorsal horn destruction, lesions of the thalamus).
Crosstalk Due to Activation of Atrial Sense Marker Function of DDD Pulse Generators
Authors: BAROLD S. SERGE , FALKOFF MICHAEL D. , ONG LING S. , HEINLE ROBERT A. , SANDERS RIGHARD
Published: July 2006

We studied the occurrence and characteristics of crosstalk related to the atrial sense marker function of the Intermedics Cosmos DDD pulse generator in 29 patients. Upon activation of the atrial sense markers, the pulse generator delivers a series of markers in the form of triggered atrial stimuli at 0.025 ms in duration at the programmed voltage output of the atrial channel. Under certain circumstances, these atrial sense marker stimuli may cause crosstalk when they are sensed by the ventricular sensing amplifier. This form of crosstalk may be eliminated in most cases by decreasing ventricular sensitivity and/or atrial output voltage.
Exercise Testing in the Diagnosis of Sick Sinus Syndrome in the Elderly: Implications for Treatment
Authors: JOHNSTON* FIONA A. , ROBINSON JOHN F. , FYFE THOMAS
Published: July 2006

Twenty‐three elderly patients underwent treadmill exercise testing to fatigue; 11 patients had sick sinus syndrome (7 males, 4 females; age range 71–91 years, mean, 78 years); 12 elderly persons were controls (5 males, 7 females; age range 70–93 years; mean, 76 years). All were euthyroid. The study showed that patients with sick sinus syndrome compared with the control group demonstrated a lower resting heart rate, a smaller increase in heart rate during exercise, poorer exercise tolerance, and differences in heart rate during the recovery phase. The value of the effort test in relation to the diagnosis of sick sinus syndrome is discussed, together with its possible implications in the choice of pacemaker.
A New Rate‐Modulated Pacemaker System Optimized by Combination of Two Sensors
Authors: ALT ECKHARD , THERES HEINZ , HEINZ MICHAEL , MATULA MARKUS , THILO RUDOLF , BLÖMER HANS
Published: July 2006

A new rate‐modulated pacemaker system optimized by combination of two sensors is described. The parameter body activity and central venous blood temperature control the pacemaker rate. The specific characteristic of each parameter determines its role within the algorithm. While the motion sensor yields a fast reaction following the onset or a change of stress intensity, central venous blood temperature corresponds better to body metabolism. An indication of increased exercise from the motion sensor results in an accordingly rapid increase in the pacing rate. Unless this increased exercise is confirmed by an increase in central venous blood temperature within 2 or 3 minutes, the new motion level will be assumed to he the new baseline motion value and the pace rate will return to a basic pacing rate. Prolonged inappropriate responses are therefore avoided. Longer lasting exercise, fever and nonphysiological signals are recognized and handled safely. Exercise tests with five volunteers under various conditions showed pacing rate behavior that was close to normal.
Failure of the Exercise Test to Predict the Anterograde Refractory Period of the Accessory Pathway in Wolff Parkinson White Syndrome
Authors: DAUBERT CLAUDE , OLLITRAULT JACKY , DESCAVES CHRISTIAN , MABO PHILLIPPE , RITTER PHILLIPE , GOUFFAULT JACQUES
Published: July 2006

Modifications of the delta wave on the surface ECG during an exercise stress test were compared to electrophysiological variations in accessory pathway (AP) refractoriness and in AV node conduction, during intravenous isoproterenol infusion in ten patients with WPW syndrome. In one patient, the delta wave persisted unchanged at the end of exercise and, with isoproterenol, there was a greater reduction in the AP anterograde effective refractory period (AEHP) than in AV node conduction time. In three patients, the delta wave became less and less apparent but without completely disappearing; in these patients, the slight reduction of the AERP in the accessory pathway with isoproterenol was comparable to the reduction in AV node conduction time, explaining the progressive fusion between the two activation fronts. In the six other patients, the delta wave completely disappeared during exercise: in two cases, suddenly from one cycle to the next with strong concordance between the measured (isoproterenol) and the estimated (exercise test) AERP in the AP; in four cases, the disappearance was progressive with a significantly greater reduction in the AV node conduction time than in the measured AEHP of AP which was nonetheless very short, 190 to 225 ms, during isoproterenol infusion. These findings confirm the limitations of the exercise test to predict the AERP of the AP. In addition, they demonstrate that modifications in the delta wave during exercise result from a balance between the relative effects of sympathetic stimulation on refractoriness of AP and normal AV conduction.
Influence of AV Synchrony on the Plasma Levels of Atrial Natriuretic Peptide (ANP) in Patients with Total AV Block
Authors: STANGL K. , WEIL J. , SEITZ K. , LAULE M. , GERZER R.
Published: July 2006

ANP was determined in 13 patients with DDD pacemakers due to total AV hock, at rest and during bicycle ergomeny under both pacing modes, DDD and WI (70/min). Under DDD pacing, the mean ANP level (normal range 5–95 pg/mL) at rest was 36 ± 18 pg/mL (mean ± SD) and increased significantly by the /actor of 3.5 so 1 27 pg/mL during exercise (p < 0.01). By just changing the pacing mode to VVI, the ANP levels rose to 73 ± 28 pg/mL (p < 0.01) at rest (= 203% of DDD resting level) and to 216 ± 184 pg/mL (= 170% of DDD peak level) during exercise P < 0.01). These results show that under AV synchronous pacing, the ANP levels we generally lower. A possible explanation for this increased release of ANP during asynchronous WI pacing is the acute increase of the atrial wall tension which occurs when the atria contacts during the systole against closed AV valves.
Postoperative Infection with the Automatic Implantable Cardioverter Defibrillator: Clinical Presentation and Use of the Gallium Scan in Diagnosis
Authors: KELLY PATRICIA A. , WALLACE SANDRA , TUCKER BERNARD , HURVITZ RICHARD J. , ILVENTO JOSEPH , MIRABEL GLORIA S. , CANNOM DAVID S.
Published: July 2006

This report describes three patients with infection involving an automatic implantable cardioverter defibrillator. All three patients presented with fever, fluid in the pulse generator pocket, leukocytosis and an elevated erythrocyte sedimentation rate. A gallium scan, together with aspiration and culture of the fluid from the pocket, confirmed the diagnosis in each case.
Selective Vibration Sensing: A New Concept for Activity‐Sensing Rate‐Responsive Pacing
Authors: LAU C.P. , STOTT J.R.R. , TOFF W.D. , ZETLEIN M.B. , WARD D.E. , CAMM A.J.
Published: July 2006

A clinically available model of an activity‐sensing, rate‐responsive pacemaker (Activitrax, Medtronic) utilizes body vibration during exercise as an indicator of the need for a rate increase. Although having the advantage of rapid onset of rate response, this system lacks specificity and the rate response does not closely correlate with the level for exertion. In addition, this pacemaker is susceptible to the effects of extraneous vibration. In this study involving 20 normal subjects fitted with an external Activitrax pacemaker, the rate responses to a variety of exercises were studied and were compared with the corresponding sinus rates. The vibration generated at the level of the pacemaker was also measured by accelerometers in three axes. Only a fair correlation (r = 0.51) was achieved between the pacemaker rate and the sinus rate. The total root mean square value of acceleration in either the anteroposterior or the vertical axes was found to have a better correlation (r = 0.8). As the main accelerations during physical activities were in the lower frequency range (0.1–4 Hz), a low‐pass filter was used to reduce the influence of extraneous vibration. Selective sensing of the acceleration level may be usefully implemented in an algorithm for activity pacing.
Noninvasive Temporary Pacemakers
Authors: GOULD BRIAN A. , MARSHALL ANDREW J.
Published: July 2006

Temporary transcutaneous pacing involves passing a variable current across the chest wall synchronized to sensed electrical signals. We evaluated two systems, the Cardio‐Aid and Pace‐Aid both in routine, and emergency use, The Cardio‐Aid was tested on 12 patients (9 routine and 3 emergency) and the Pace‐Aid was tested alone in 4 patients [2 emergency and 2 routine). Both systems were tested on a further 7 patients (2 emergency and 5 routine). Overall, successful pacing was achieved in 3 out of 19 patients with the Cavdio‐Aid (1 emergency) and in 4 out of 11 patients with the Pace‐Aid (3 emergency). The maximum current used was limited by the degree of pain experienced. These data suggest that the benefit derived from transcutaneous pacing is limited. The pain experienced by patients may be diminished by appropriate analgesics and sedation, thereby allowing a greater pacemaker output particularly in an emergency situation.
Limitations of Rate Response of an Activity‐Sensing Rate‐Responsive Pacemaker to Different Forms of Activity
Authors: LAU CHU‐PAK , MEHTA DAVENDRA , TOFF WILLIAM D. , STOTT ROLLIN J. , WARD DAVID E. , CAMM A. JOHN
Published: July 2006

The responses of an activity‐sensing rate‐responsive system (Activitrax) to various forms of physiological activity were assessed in 15 individuals who had this pacemaker. Nine were patients with complete heart block and atrial arrhythmias; their mean age was 60 years (range, 41–85 years). Six were age‐matched healthy volunteers who were exercised with an external Activitrax system attached firmly to the chest wall. The pacemaker was programmed to achieve a pacing rate of about 100 bpm at the end of the first stage of the Bruce protocol (pacemaker settings; rate = 70–150 bpm; threshold = low to medium; response = 6–9). In the activity‐sensing ventricular pacing mode, oil patients achieved a significant increase in treadmill time compared to constant‐rate ventricular pacing (mean ± SD, 8.0 ± 3.3 vs 5.4 ± 2.3 minutes; p < 0.01), with a mean maximum pacing rate of 123 ± 18 bpm. Jogging in place produced a prompt increase in pacing rate, with the maximum achieved at the end of the exercise. However, physiological activities such as hand‐grip, the Valsalva maneuver and standing resulted in only minimal rate response. Pacing rate after ascending 4 flights of stairs was the same as that achieved after descending the same stairs (100 ± 8 vs 105 ± 4 bpm; p < 0.1). All 15 subjects were exercised from resting heart rate for 3 minutes on a treadmill at 1.2 mph and 2.5 mph with four gradients at each speed. Although the pacing rate increased with a faster treadmill speed (p < 0.005), it did not respond appropriately to a change in gradient compared to the sinus rate. We conclude that although activity‐sensing rate‐responsive pacing gives a prompt increase in pacing rate and improves maximum exercise tolerance, further refinement is necessary because: (1) physiological activities not associated with significant movement are not detected by this pacing system; (2) detection of vibrations as an indicator of activities does not correlate well with the level of exertion.
The Ventricular Intracardiac Unipolar Paced‐Evoked Potential in an Isolated Animal Heart
Authors: ECONOMIDES APOLLO P. , WALTON CHRISTOPHER , GERGELY STEPHEN
Published: July 2006

The endocardial unipolar paced evoked response has excited a great deal of interest due to its possible use in the measurement of the metabolic state of the body and other pacer‐related areas. Although rate‐responsive pacing utilizing this signal has been clinically evaluated, little is known regarding the behavior of the components of this waveform under normal physiological conditions. We have developed an electronic circuit which allows the recording of the evoked response within a few milliseconds of a pacing stimulus of 5 V and 0.5 ms duration being applied using a single unipolar, smooth platinum electrode of 14 mm2 surface area. The paced evoked response was measured using a total of 20 isolated rabbit heart preparations. Five were run for 8 hours and the remaining fifteen were run for 5 hours. Our results indicate that the waveform components of the evoked response remain stable while the preparation is viable, but that two of the time‐related measurements change with loss of viability. A significant lengthening of the stimulus‐R interval was seen together with a dramatic shortening of the R‐T period. The net result of these changes was an overall reduction of 17% in the complex duration. In addition, we found the H‐T shortening to be a sensitive measure of myocardial integrity. We conclude that the combination of our interface charge elimination circuit and the isolated heart preparation has proved a useful system for the investigation of the paced evoked potential. Furthermore, the loss of myocardial viability has a complex action on this response.