bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrolysis of Unipolar Pacing Leads
Authors: ISBARY JOBST E. , KRONSKI DIETER , KOENIG ERWIN
Published: July 2006

A 90‐year‐oJd man with bradycardia and Stokes‐Adams attacks had a unipolar VVI pacemaker implanted. Twice within a short period of time we registered a total Joss of function: the first incident was caused by a “fracture” between lead and electrode, and the second was due to partial dissolving of the lead. Both times a new lead electrode was implanted; the second time we replaced the pulse generator as well. Pacemaker analysis showed a capacitor defect leading to a 50 microampere anodal DC leakage that caused electrolysis of the helical coil conductors. The patient had no clinical symptoms besides those due to loss of pacemaker function. The present case report and others in the literature indicate that when an electrode lead fracture is found, it is necessary to check the pacemaker for DC leakage.
Normal Electrophysiological Findings in a Patient with Symptomatic Intermittent Advanced Atrioventricular Block
Authors: HUANG SHOEI K. , HAUSER ROBERT G. , EZRI MARILYN D. , DENES PABLO , MESSER JOSEPH V. , ANBE DANIEL T.
Published: July 2006

This report describes an otherwise healthy young woman who presented with syncope during episodes of advanced atriovenlricular (A V) block. The His bundle recordings during normal sinus rhythm and atrial and ventricular pacing were normal. Carotid sinus massage produced no abnormality. Subsequently, (he patient received a permanent pacemaker and has been free of symptoms. In termittent advanced A V block has been observed on follow‐up electrocardiograms. This unique case demonstrates a potential limitation of routine electrophysiologic investigation.
Dual AV Nodal Pathways—Vagal Influences on AV Nodal Conduction
Authors: EZRI MARILYN D. , HUANG SHOEI K. , CHHABLANI RAMESH , DENES PABLO
Published: July 2006

This 52‐year‐old male presented with syncope and demonstrated two distinct PR intervals on the electrocar‐diogram. Electrophysiologic studies showed dual A V nodal path ways. Right‐sided carotid sinus massage induced prolonged periods of sinus arrest with no change in AH interval. Left‐sided carotid sinus massage produced long AH intervals (slow pathway conduction) with some slowing of sinus rate. Whenever sinus rhythm with slow pathway conduction was observed (long AH) a 20‐30 mmHg drop systolic pressure was seen. Following implantation of an AV sequential pacemaker, the patient has been asymptomatic.
On Line (Real Time) Quantitative Measurement of Premature Ventricular Beats
Authors: WAXMAN MENASHE B. , FEDORKOW GUY , CAMERON DOUGLAS , SHARMA ARJUN
Published: July 2006

A real time system for graphically displaying premature ventricular beat trends is described. The system consists of analog detector circuits coupled to a Fortran based software program for premature ventricular beat processing. The software program runs four independent channels and has three available analysis modes: a “counting” mode which provides a running total of counts to date; an “averaging” mode which displays average number of events overtime, and a “ratio” mode which provides an output reflecting changes in the ratio of premature ventricular beats to all beats. Various scale factors can be applied to accommodate differing background states. The system's strengths lie in its simplicity, accuracy, and simultaneous analog display of both the original ECG signal as well as the derived quantitative data.
Use of the Contralateral Subclavian Vein for Placement of Atrial Electrodes in Chronically VVI Paced Patients
Authors: BELOTT PETER H.
Published: July 2006

Two patients with documented pacemaker syndrome were referred for AV sequential pacing and were found to have inaccessible venous systems on the side of their original transvenous pacemaker placement. The confralateral subclavian vein was subsequently catheterized with an atrial electrode using the sheathset technique, Then the proximal aspecf of the atrial endocardial lead was tunneled to the original pacemaker pocket, Once accomplished, both (atrial and ventricular) leads were connected to an AV sequentiat pulse generafor. The united puise generalorand lead were reinserted in the original pacemaker pocket.
Timing Markers Showing Pacemaker Behavior to Aid in the Follow‐Up of a Physiological Pacemaker
Authors: KRUSE IB , MARKOWITZ TOBY , RYDÉN LARS
Published: July 2006

In the present study a multiprogrammable, atriul synchronous, ventricular inhibited pacemaker (Enertrax) was used in six patients. This pacer makes it possible to evaluate pacemaker performance nonmvasively and facilitates the correct interprefation of the djfficult ECGs produced by these complex pacemakers.
Initial Experience with Universal Pacemakers
Authors: DUNCAN JENNIFER , GOLDMAN BERNARD S. , CHISHOLM ARTHUR W. , PYM JOHN , CAMERON JAMES , NOBLE EDWARD J.G. , ADELMAN ALAN G. , CAMERON DOUGLAS , WAXMAN MENASHE
Published: July 2006

Thirty‐five patients were implanted with the Sequicor DDD pacemaker between September l, 1981 and March 1, 1982. The mean age was 61.7years (range, 17–88). According to their ECGs, the patients fell into two distinct groups—those with A‐V block and those with sick sinus syndrome. Our initial experience has indicated an excellent eleo tronic component furtction (except for l discrepant reed switch); high battery drain of the Sequicor; complications similar to those seen with DVI or VVI pacing; and an increase in the hemodynamic benefits resulting from DDD as compared to DVI or VVI pacing in 70% of patients.
Atrial Flutter Secondary to Hypokalemia
Authors: VARRIALE PHILIP , KWA RAYMOND P. , PARIKH NARESH
Published: July 2006

Electrophysiologic studies support significant hypokalemia as a cause of atrial flutter in a patient without manifest heart disease. Atrial flutter, reproducibly initiated and terminated by rapid atrial pacing during hypokalemia, was not inducible after potassium correction. In an individual with existing atrial conduction disease, hypokalemia may generate both non‐uniform atrial refractoriness and atrial premature beats, and it may facilitate the development of atrial flutter as a re‐entrant arrhythmia.
Sensing Characteristics of the Right Atrial Appendage Electrode
Authors: GRIFFIN JERRY C.
Published: July 2006

In order to expiore fully the sensing characteristics of both bipolar and unipoiar configurations of the tined right atrial appendage electrnde, detailed electrographic analysis was performed in 30 patients undergoing atrial electrode? implantalion. Though no differences were noted between unipolar and bipolar atrial deflecfions in electrograms from these leads, the unipolar ventricular deflections were greater in both amptitude (1.9 vs 0.6 m V) and slew rate (0.37 vs 0.07). These data suggest that bipolar pacing configurations might be preferable when selective atrial sensing is important.
A Permanently Implanted Endocardial Electrode Complicating Ventricular Tachycardia with A Second VT
Authors: PINAKATT TERESA , IESAKA YOSHITO , ROZANSKI JOHN J. , GOSSELIN ARTHUR J. , LISTER JOHN W.
Published: July 2006

A VVI pacemalter was permanently implanted for the purpose of suppressing recurrent ventricular tachycardia (VT). Not only did the device fail to suppress the VT, but also the permanent endocardial electrode caused a second VT which was more rapid and clinically more severe. When a new VT occurs in the presence of a permanently implanted ventricular pacing system, the implanted electrode should he considered as one of the possible etiologic causes for the VT.
Acute Myocardial Ischemia During Pacemaker Implantation: Implication for Threshold Determinations and Potential Complications
Authors: SNOW NORMAN
Published: July 2006

The onset of acute myocardial ischemia during pacemaker implantation may strikingly alter measured threshold values so that unnecessarily high generator output parameters are programmed. In addition, ischemia muscle is more vulnerable to malignant arrhythmias if the stimulating electrode is in an ischemic area. Two patients are presented whose threshold values rose sharply during an ischemic attack and returned to baseline after the angina subsided. Relief of angina is a clinically useful determinant of the safety necessary to proceed with implantation and threshold measurements
Atrio‐Ventricular and Ventriculo‐Atrial Conduction Times in Patients Undergoing Pacemaker Implant
Authors: HAYES DAVID L. , FURMAN SEYMOUR
Published: July 2006

Pacemaker mediated reentrant tachycardias have been seen frequently during use of dual chamber sensing pacemakers and are dependent on the presence of intact retrograde (ventriculo‐atrial) conduction. The status of a patient's retrograde (VA) conduction cannot be determined from the surface electrocardiogram. At the time of pacemaker implant the state of ante‐grade conduction should be determined at incremental atrial pacing rates, the exact timing measured from the intracardiac electrograms, i.e., from the intrinsic deflection of the atrium to the intrinsic deflection of the ventricle. With this information obtained in 53 patients, if was possible to determine which patients could safely receive dual chamber sensing pacemaker devices, the appropriate pacemaker atrial refractory period setting to avoid pacemaker mediated tachycardias in those patients with intact retrograde conduction, and the optimal timing for programming the pacemaker's A V delay. Patients who have been studied in this manner and who were felt to be suitable for a dual chamber sensing device have not displayed pacemaker mediated reentrant tachycardias. Forty‐seven percent of all patients who require pacemaker implant have VA 1:1 conduction; 67% of those with sinus node dysfunction and 14% of those with complete antegrade block have VA conduction at a mean interval of 235 ± 50 ms (range 110–380 ms).
Malposition of A Transvenous Cardiac Electrode Associated with Amaurosis Fugax
Authors: ROSS WILLIAM B. , MOHIUDDIN SYED M. , PAGANO THOMAS , HUGHES DAVID
Published: July 2006

A 55‐year‐old male received a transvenous ventricular pacemaker for sick sinus syndrome. After pacemaker insertion, he developed recurrent episodes of amaurosis fugax. The source of thromboemboli was the pacemaker electrode malpositioned in the left ventricle. Position of the electrode was diagnosed correctly by two‐dimensional echocardiography. The malposifioned electrode was successfully removed with cessation of recurrent thromboembolic phenomenon.
Atrioventricular Block in Situs Ambiguus and Left Isomerism (Polysplenia Syndrome)
Authors: ROGUIN N. , PELLED B. , FREUNDLICH E. , YAHALOM M. , RISS E.
Published: July 2006

Three patients are described who had situs ambiguus and left isomerism (polysplenia syndrome) and advanced atrioventricuiar block. One presented with a complex bradyarrhythmia with Wenckebach block. The other two had congenital atrioventricular block with a narrow QRS at a ventricular rate of 80 per minute, an atrial rate of 150′ per minute, and both had a P wave axis directed superiorly and to the right in one, and superiorly to the left in the other. This ECG pattern was not observed in more than 400 adult patients with complete A‐V block treated in our service. It is our opinion that in infants and children with heart disease the presence of complete A‐V block with narrow QRS and an unusual P waves axis directed superiorly is strongly suggestive of left isomerism. The incidence rate of complete A‐V block in left isomerism is nearly twenty percent of the cases described.
Comparative Functional Effects of Chronic Ventricular Demand and Atrial Synchronous Ventricular Inhibited Pacing
Authors: YEE RAYMOND , BENDITT DAVID G. , KOSTUK WILLIAM J. , KO PATRICK T. , PURVES PAUL , KLEIN GEORGE J.
Published: July 2006

We compared the effects of chronic ventricular inhibited (VVI) and atrial synchronous ventricular inhibited (VDD) pacing on functional capacity in 8 patients with complete atrioventricular heart block. Permanent VDD (Medtronic #2409, ASVIP) pacemakers were implanted in four men and four women (age range 27–76 years, mean 58.9 ± 18.4 years), and randomly assigned to a three‐month period of VDD or VVI pacing in this single blinded, crossover study. Functional capacity was assessed by questionnaire, graded treadmill exercise testing and radionuclide angiocardiography prior to pacemaker implant and following each pacing period. Following 3 months of pacing in each of VVI and VDD pacing modes, maximum heart rate [83.4 ± 14 vs 134.9 ± 16.4 beats/min. p < 0.001) and double product (147.5 ± 58.3 vs 218.9 ± 52.7, p < .001) were greater with VDD pacing. Although exercise duration on treadmill exercise testing (5.3 ± 2.9 vs 6.9 ± 3.1 minutes, p < 0.1) was greater in the VDD mode, the difference was not significant. Similarly, there was no significant difference in functional capacity as measured by questionnaire scores (50.1 ± 8.4 vs 46.9 ± 8.9, p < 0.1) or in left ventricular ejection fraction for the two pacing modes [.54 vs .55, p < .5). Only one patient reported a subjective improvement with physiologic [VDD] pacing, whereas the remaining patients stated no preference. We conclude that VDD pacing offers improved maximal cardiac work during exercise compared to VVI pacing. However, many patients may be limited in maximal exercise capacity by non‐cardiac factors and may not appreciate this difference.
A New Type of Ventriculo‐Atrial Gap Phenomenon in Man
Authors: WEISS JAMES , STEVENSON WILLIAM G.
Published: July 2006

A new type of ventriculo‐atrial (V‐A) gap phenomenon was observed in a patient who underwent a cardiac electrophysiology study and had complete antegrade infranodal A‐V block but intact V‐A conduction. During ventricular extrastimulus testing, a split retrograde His potential emerged from the ventricular electrogram. As the prematurity of the extrastimulus was increased, the later of the two retrograde His deflections disappeared suddenly at a critical coupling interval and V‐A conduction was interrupted. More premature extrastimuli resulted in progressive delay in the His‐Purkinje system and delayed appearance of the earlier retrograde His deflection. As a result of this delay, conduction through the His bundle eventually resumed, the second (split) retrograde His reappeared and conduction to the atria resumed. Thus, the initial site of block during the V‐A gap phenomenon in this patient was located in the His bundle, with proximal delay occurring in the distal His‐Purkinje system. The results indicate that the classic mechanism of gap phenomenon is operative. To our knowledge, this type of V‐A gap phenomenon has not been previously described in man.
Steroid Treatment of the Painful Pacemaker Pocket
Authors: KRATZ JOHN M. , CAMPBELL WILLIAM C. , LEMAN ROBERT B. , HARVIN J. SHAND
Published: July 2006

Chronic pain about a pacemaker secondary to sterile fibrotic contracture of the capsule is an uncommon but frustrating complication for both the physician and the patient. Three cases of this complication controlled by the late injection of triamcinolone are reported.
Nonsurgical Electrical Ablation of Tachycardias: Importance of Prior in Vitro Testing of Catheter Leads
Authors: FISHER JOHN D. , BRODMAN RICHARD , JOHNSTON DEBRA R. , WASPE LAWRENCE E. , KIM SOO G. , MATOS JEFFREY A. , SCAVIN GALE
Published: July 2006

Nonsurgical electrical ablation of tachycardia pathways or foci has been attempted or carried out using a variety of temporary pacing catheter leads. To determine the ability of such leads to withstand the high energies used in such procedures, 34 leads were suspended in saline, and subjected to repeated electrical shocks. Small (4 French) temporary pacing leads made by a variety of manufacturers tolerated multiple shocks up to 100 joules; above this level, failures became increasingly common, although usually the failure mode was benign with respect to patient care implications. Testing of 6, 7, and 8 French leads revealed considerable inter‐and intra‐manufacturer differences in the ability to withstand higher energy shocks, reflecting differences in materials and fabrication techniques. It is concluded that careful in vitro lead testing is required prior to using identical models in humans for arrhythmia ablation procedures.
A Decade of Nuclear Pacing
Authors: PARSONNET VICTOR , GILBERT LAWRENCE , ZUCKER I. RICHARD , WERRES ROLAND , ATHERLEY TREVOR , MANHARDT MARJORIE , GORT JANE
Published: July 2006

In April, 1973, a decade‐long study was begun on nuclear‐powered pacemakers. The first 15 of these were designed by the Numec Corporation under a contract from the United States Atomic Energy Commission. Altogether 151 units powered by the isotope Plutonium 238 were implanted in 131 patients; the pacemakers of 4 different manufacturers were used. The last nuclear pacemaker was implanted in January, 1983. The actuarial survival at 10 years was 92%, meeting the original performance goal of the Commission of 90%. Ninety pulse generators are still in service today; 25 patients have died and 36 pulse generators have been replaced with non‐nuclear units. The most common indication for replacement was an inappropriate pacing mode. This high reliability and superior performance suggest that continued use of a radioisotopic power source is justified, particularly if combined with the electronic circuits of today's dual‐chambered, multiprogrammable, and multifunctional pacemakers.
Pacemaker Alternans
Authors: Rozanski John J. , Kleinfeld Morris , Worthington Francis X. , Lister John W.
Published: July 2006

A 52‐year‐old man was implanted with a Gemini pacemaker for complete heart block which developed suddenly three months after coronary reconstruction and endocardial resection to treat chronic recurrent ventricular tachycardia. Pacemaker alternans, which is a rare phenomenon, occurred two days after pacemaker implantation and then disappeared 24 hours later. The patient was followed for a two‐month period during which the pacemaker system functioned normally. Many of the possible mechanisms which may produce pacemaker alternans were explored. Our findings are presented in this report.
“Pseudo‐endless Loop” Tachycardia in an AV Universal (DDD) Pacemaker
Authors: AMIKAM SHLOMO , ANDREWS CAROLYN , FURMAN SEYMOUR
Published: July 2006

A 3‐beat episode of ventricular arrhythmia was recorded in a patient with an AV universal (DDD) pacemaker. This arrhythmia mimicked “endless loop” tachycardia (ELT) because it appeared following a ventricular premature contraction (VPC), its rate approached the preset upper‐rate limit and the regular P waves disappeared during the episode. However, as retrograde conduction was absent ELT could not exist. The mechanism of this arrhythmia was based on a combination of interference by VPC of the regular sequence of this complexes produced by P wave and the pacemaker commitment to maintain an upper rate limit by prolongation of the programmed pacemaker AV delay.
Recurrent Sepsis from Retained Endocardial Electrode in Children: Successful Removal with Cardiopulmonary Bypass*
Authors: DeLEON SERAFIN Y. , BOJAR ROBERT , KOSTER NANCY K. , ILBAWI MICHEL N. , MUNEZ HENRY , IDRISS FAROUK S.
Published: July 2006

Infection remains a significant problem in patients undergoing permanent cardiac pacemaker implantation, and removal of all components is usually required. The transvenous system carries minimal morbidity at implantation, but the development of infection is more life‐threatening than in the epicardial system. Although the evolution of the tined porous endocardial lead reduced the incidence of wire displacement, the development of a serious infection is still a problem and may require major surgery for removal. We experienced this problem in a 15‐month‐old child who developed recurrent sepsis. Attempts at removal of the retained tined porous electrode through the neck incision proved dangerous and unsuccessful. Removal was carried out using cardiopulmonary bypass and infection was promptly controlled.
Resetting of DDD Pacemakers Due to EMI
Authors: BELOTT PETER H. , SANDS STEVEN , WARREN JAY
Published: July 2006

Multiprogrammable pacemaker have long been subject to inappropriate reprogramming and electromagnetic interference (EMI). A limited clinical experience with DDD pacing systems precludes the significance of such phenomena in these units. Since August 1981, in a series of 140 DDD systems, certain units demonstrated consistent and reproducible resetting to the hack‐up modes caused by electrocautery. One unit was permanently reset to the VOO mode. These observations suggest the need for renewed caution at the time of surgery; they also underscore the importance of a thorough understanding of any DDD system and careful follow‐up so that such phenomena will not be misinterpreted as pacemaker failure, resulting in erroneous pacemaker removal.
DDD/DDT Pacemakers in the Treatment of Ventricular Tachycardia
Authors: FISHER JOHN D. , FURMAN SEYMOUR , KIM SOO G. , MATOS JEFFREY A. , WASPE LAWRENCE E.
Published: July 2006

The possibility of adapting multimode dual‐chamber pacemakers for programmed and burst stimulation was explored in a group of patients with ventricular tachycardia. The potential usefulness and pitfalls of these pacemakers were exemplified in one patient, presented in detail. The implanted DDD pacemaker was programmed to an all‐synchronous mode (DDT), permitting programmed ventricular stimulation through synchronization with chest wall stimulation provided by a standard external programmable stimulator. With the ventricular sensing refractory period shortened to 200 ms, both programmed electrical stimulation and burst pacing for termination of induced tachycardias were possible. When medications failed to offer protection against the patient's tachycardias, the ventricular sensing refractory period (and minimum stimulation interval) was increased to 300 ms, thereby permitting burst pacing at up to 200 beats/minute for termination of spontaneous episodes, After many trials to confirm the efficacy of such stimulation, and the lack of muscle potential triggering, the patient was discharged home with the pacemaker in the DDT mode. He was instructed to go to his local emergency room, and was equipped with a portable device to trigger his implanted unit. Subsequently, the patient had successful termination of several spontaneous episodes of ventricular tachycardia in an emergency room. Later, he began to experience palpitations during certain exercises, and it was found that the implanted unit was being triggered by pectoral myopotentials. The unit was there/ore reprogrammed to decrease the sensitivity, and the patient was again discharged. The need for careful evaluation and close follow‐up is emphasized to maximize the benefits and to minimize the very serious potential risks of this pacing mode.
Swine as an In Vivo Model for Electrophysiologic Evaluation of Cardiac Pacing Parameters
Authors: BOWMAN TERESA A. , HUGHES HOWARD C.
Published: July 2006

Pre‐clinical studies of cardiac pacemakers and new electrodes, materials, and designs are for the most part conducted in dogs. Dogs, however, have electrophysiological differences which may preclude accurate translation to clinical trials. The purpose of this study was to develop normal electrophysiological parameters for an animal whose cardiovascular system more closely resembles that of man than any nonprimate animal. The threshold (voltage and current) strength‐duration curves of the pig showed the same inverse relationship between the pulse duration and threshold requirements as other species. At 0.5 ms the atrium had 3.5–5.5 times greater energy requirements, over twice the current (2.04 mA vs 0.72 mA) and twice the voltage (0.75 mV vs 0.32 mV) requirements when compared to the ventricles. The pig's S‐A nodal P‐wave was superior in amplitude (7.80 ± 1.80 mV vs 4.28 ± 2.27 mV) and the slew rate was faster (1.30 ± 0.56 mV/ms vs 0.44 ± 0.50 mV/ms) compared to that of the atrial appendage. The pig's left ventricular myocardial R‐wave had significantly greater amplitude (19.00 ± 6.44 mVvs 10.70 ± 4.34 mV) and faster slew rate (1.60 ± 0.62 mV/ms vs 0.90 ± 0.30 mV/ms) compared to the right ventricular endocardial R‐wave. The electrophysiological parameters of the pig were more similar to those of man than the dog; therefore, the pig is a useful animal model for electrophysiological studies and the testing of pacemaker equipment.
Early and Late Efficacy of Three Types of Transvenous Atrial Leads
Authors: PEHRSSON S. KENNETH , BERGDAHL LEIF , SVANE BERTIL
Published: July 2006

Experience with three transvenous atrial leads, representing different principles, is presented. The types were screw‐in (Vitatron Helifix‐12), J‐lead (Intermedics Lifeline 483–01) and straight‐tined (Medtronic 6961). The study comprised insertion of 86 leads (30 Helifix, 40 Lifeline, 16 Medtronic) in 76 patients. Atrial fibrillation occurred during insertion in two patients, and in two others stable electrode positioning in the right atrial appendage was not achieved. Stable position and acceptable intracardiac P‐waves were obtained in all the other patients (in 5 after change to another type of lead). Atrial triggered ventricular pacing was used in 34 cases and atrial pacing was used in 38. The P‐wave amplitude at insertion was significantly less with Helifix than with Lifeline or Medtronic. The stimulation thresholds (range 0.25–2.5 V) did not differ significantly between the electrodes. Dislodgement of the electrode occurred during the first week in seven cases (5 Lifeline, 2 Helifix), but no late dislodgement occurred. The mean follow‐up was 14 months (range 1–31). All three atrial leads offer acceptable function with regard to electrophysiological properties and electrode stability.
Responses of an AV Universal (DDD) Pulse Generator (Cordis 233D) to Programmed Single Ventricular Extrastimuli
Authors: van MECHELEN ROB , HAGEMEIJER FRANS , de JONG JAN , de BOER HANS
Published: July 2006

To evaluate factors playing a role in initiation and perpetuation of pacemaker‐mediated tachycardias (PMTs), 22 consecutive patients with symptomatic conduction disorders were studied after implantation of an AV universal (DDD) pulse generator (Cordis 233D). Patients were divided into two groups, depending upon the presence or absence of ventriculoatrial (VA) conduction during electrophysiological study (EPS) performed before pacemaker implantation. PMTs couid be initiated in six of eight patients of Group I and in none of 14 patients of Group II. Initiation and perpetuation of PMTs during DDD pacing were dependent upon the capacity of the patient to conduct ventricular premature beats (VPBS) and subsequent paced ventricular beats retrogradely to the atria, and upon three programmable parameters of the pulse generator (AV delay period, upper rate limit, tachycardia response).

Programmed single ventricular extrastimulation demonstrated that: (1) merely the presence of VA conduction during EPS, although necessary, was not sufficient to induce PMTs after DDD pacemaker implantation; (2) VPBs introduced late rather than early in the cardiac cycle initiated PMTs in a different way; (3) the initiation of PMTs could be prevented during study by adjusting the programmable parameters (AV delay period, upper rate limit, tachycardia response); (4) one of the two available tachycardia responses of the pulse generator (gradual fall‐back response) was able to terminate and initiate PMTs consistently.

These observations helped in understanding the responses of the Cordis 233D pulse generator to ventricular premature beats. They indicate that additional refinement of the pulse generator is necessary to solve the problem of PMT.
External Non‐invasive Cardiac Pacing: A Comparative Hemodynamic Study of Two Techniques with Conventional Endocardial Pacing
Authors: NIEMANN JAMES T. , ROSBOROUGH JOHN P. , GARNER DANIEL , ARONSON ALFRED L. , CRILEY J. MICHAEL
Published: July 2006

Out‐of‐hospital therapy for cardiac arrest due to bradyarrhythmias or asystole is pharmacologic and the outcome is uniformly dismal. Optimal therapy for the latter disturbances may be artificial cardiac pacing, but conventional invasive pacing techniques are not employed or are of limited value in the out‐of‐hospital and emergency department selling. This investigation compared the hemodynamic effects of two techniques of non‐invasive external pacing: 1) transcutaneous transthoracic pacing (TTP) and 2) tongue‐to‐epigastrium pacing (TEP), with conventional transvenous right ventricular endocardial pacing (RVEP) in a closed‐chest, chronic heart block canine model. All techniques significantly increased (p < .001) cardiac output (CO). However, CO and mean arterial pressure (MAP) measured during external pacing with either non‐invasive technique were significantly greater than that during RVEP (p < .001). TEP produced vigorous skeletal muscle stimulation and, in the canine model, it produced contraction resulting in impaired ventilation, hypoxemia, and a decrease in systemic vascular resistance. TTP in this model resulted in improved MAP and CO when compared with control and RVEP values and did not affect arterial or mixed venous blood gas values. Thus, this study demonstrates that noninvasive TTP is comparable to RVEP in its hemodynamic effects. TTP may offer definitive non‐invasive therapy for a subset of victims of out‐of‐hospital cardiac arrest.
Dual Atrio‐ventricular Nodal Pathways and Atrial Fibrillation
Authors: BRUGADA PEDRO , ROY DENIS , WEISS JIM , DASSEN WILLEM R.M. , WELLENS HEIN J.J.
Published: July 2006

The determinants of the ventricular rate during atrial fibrillation were studied in a group of eleven patients demonstrating dual A‐V nodal pathways during atrial stimulation. The shortest R‐R interval and the mean ventricular cycle length during at least 1 min of pacing‐induced atrial fibrillation were compared; a) to the effective and functional refractory period of the fast pathway; b) to the effective refractory period of the slow pathway determined during atrial stimulation, at two or more different basic cycle lengths of pacing; and c) to the shortest cycle length during atrial stimulation followed by 1:1 A‐V conduction. A group of 8 patients not demonstrating dual A‐V nodal pathway‐curves during atrial stimulation was used as a control. In both groups the shortest R‐R interval during atrial fibrillation was best predicted by the shortest cycle length followed by 1:1 A‐V conduction during atrial stimulation. The mean ventricular cycle length during atrial fibrillation was not accurately predicted by any of the variables studied. The similar results in patients with and without dual A‐V nodal pathways suggest that concealed conduction from one to another A‐V nodal pathway does not play a role in determining the ventricular response during atrial fibrillation in patients with dual A‐V nodal pathways.
Atrial Trigeminy Induced by a Normally Functioning DVI Pacemaker
Authors: MILLAR ROBERT N. SCOTT , OBEL I.W. PROMUND
Published: July 2006

Atrial trigeminy was seen in a patient with a normally functioning DVI pacemaker (Byrel‐5992). Atrial competition resulted from coincidence of sinus and atrial escape rates together with late ventricular sensing. This resulted in atrial output stimuli occurring within the QRS complex. Alternate impulses occurred late enough to conduct to the ventricle after recovery of tbe AV node. Reprogramming the pacemaker to either a faster DVI rate or to VVI abolished the arrhythmia.
Ventricular Tachycardia with Alternate Ventriculo‐atrial Wenckebach Conduction Due to Two‐level Block
Authors: WEHR MICHAEL , BRUGADA PEDRO , GREEN MARTIN , ABDOLLAH HOSHIAR , WELLENS HEIN J.J.
Published: July 2006

A 54‐year‐old patient was studied because of ventricular tachycardia following an inferior myocardial infarction. During one episode of non‐sustained ventricular tachycardia a 9:4 alternating ventriculo‐atrial Wenckebach block was noted. This was based upon a 2:1 block between the ventricles and the bundle of His and a 5:4 Wenckebach block between the bundle of His and the atria. Our study shows that alternate Wenckebach periods during ventriculo‐atrial conduction may be caused by two or more levels of block in the ventriculo‐atrial conduction system.
Atrial Fibrillation Induced by Testing Magnet Applied to VVI Pacemaker
Authors: STALLER BERNARD J.
Published: July 2006

The first known case of testing magnet‐induced atrial fibrillation in a patient with a VVI pacemaker is reported. A macro‐re‐entry mechanism is postulated, involving retrograde conduction from the ventricle through the AV node to the atrium following an asynchronous pacemaker stimulus.
Rate Hysteresis Pacing: How Valuable Is It? A Comparison of the Stimulation Rates of 70 and 50 Beats per Minute and Rate Hysteresis in Patients with Sinus Node Disease
Authors: ROSENQVIST M. , VALLIN H.O. , EDHAG K.O.
Published: July 2006

The main disadvantages of VVI pacing are absence of acceleration of the heart rate and loss of atrial synchronization. The alternatives to AAI and DDD pacing are stimulation at a low rate or hysteresis in order to decrease pacing time and thus reduce AV asynchrony. Nine patients who suffered from sinus node disease and who had been given a multiprogrammable pacemaker were monitored at each of three stimulation rates: 70, 50, and 70 bpm with an inhibition rate of 50 bpm (hysteresis).

The total pacing time was shortest (p < 0.05) for the stimulation rate of 50 bpm as compared to 70 bpm and hysteresis. It was also shorter for the hysteresis mode than for the 70 bpm mode (p < 0.05).

Only for hysteresis pacing was there a significant reduction in the number of changes from conducted cardiac rhythm to pacemaker‐induced rhythm. Most patients found the 50 bpm mode preferable. None favored the hysteresis mode.

In patients with sinus node disease and intermittent bradycardia being permanently paced, the periods of AV‐conducted rhythm may be lengthened by reducing the stimulation rate from 70 bpm, with or without hysteresis pacing, to 50 bpm. In paced patients with sinus node disease and symptoms due to AV asynchrony, it might be worth trying a decrease in the stimulation rate before resorting to other pacemaker systems.
Safety Factor for Precordial Pacing: Minimum Current Thresholds for Pacing and for Ventricular Fibrillation by Vulnerable‐period Stimulation
Authors: VOORHEES WILLIAM D. , FOSTER KIRK S. , GEDDES LESLIE A. , BABBS CHARLES F.
Published: July 2006

Temporary cardiac pacing by means of rapidly applied, precordial electrodes can be of great value in selected patients suffering cardiac arrest or profound bradycardia, post‐defibrillation atrioventricular block, or digitalis intoxication. This study provides data pertaining to the safety of precordial pacing measured as the ratio of the minimum current required to induce ventricular fibrillation (VF) to the minimum current required to pace the ventricular myocardium. Single rectangular pulse stimuli having durations of 1–50 ms were evaluated. In 6 anesthetized dogs, a cutaneous electrode was centered over the shaved apex beat area of the left chest and paired with a larger electrode sutured to the right chest wall. Using a specially fabricated, synchronized, high‐energy pulse generator, the “most vulnerable” time in the cardiac cycle at which the least current was required to induce VF with a single shock was identified. This current was compared to the much lower current required to pace the heart in the diastolic interval. While the current required to produce either fibrillation or pacing decreased as pulse duration increased, the safety factor (i.e., the ratio of fibrillation current to pacing current) remained nearly constant, averaging 12.6 for all pulse durations examined. That is, on the average, a stimulus of any given duration between 1 and 50 ms required at least 12 times the current required for pacing to produce ventricular fibrillation. We conclude that in normal canine hearts, the risk of inducing VF during precordial pacing is small.
Aspergillus Infection of a Permanent Ventricular Pacing Lead
Authors: MOORMAN J. RANDALL , STEENBERGEN CHARLES , DURACK DAVID T.
Published: July 2006

Fungal infections of intracardiac pacemakers are extremely rare. We describe what appears to be the first reported case of Aspergillus infection of a permanent pacing lead and review the three reported cases of other fungal infections of pacemaker leads which we could find in the literature. These infections may be encountered more frequently as the number of permanent pacemakers implanted in elderly patients with underlying medical illnesses continues to increase.
His Bundle Recordings Using Epicardial Pacing Wires: A New Technique
Authors: MAGILLIGAN DONALD J. , ALLOR DOUGLAS , AMLANI MAHAMADALI , PEPER WILLIAM
Published: July 2006

His bundle electrograms were recorded from the epicardial surface of the heart of nine dogs using temporary pacing electrodes. Simultaneous His bundle activity was recorded by the standard endocardial catheter technique. There was a close correlation between the AH times (r = 0.93) and HV times (r = 0.96) using both techniques. This new technique for studying His bundle activity is simple, requires no additional dissection during the performance of open heart surgery, and should be of value in diagnosing conduction system disturbances occurring in the perioperative period.
Report of the NASPE* Mode Code Committee
Authors: BERNSTEIN A.D. , BROWNLEE R.R. , FLETCHER R. , GOLD R.D. , SMYTH N.P.D. , SPIELMAN S.R.
Published: July 2006

The NASPE Mode Code Committee was formed in response to the growing need for efficient means of describing the function of increasingly complex single‐ and dual‐chamber cardiac pacemakers. After considering numeric, alphabetic, and pictorial codes, the Committee recommended the adoption of two codes: a generic code which is similar to the Revised ICHD Code and is suitable for conversational use, and a specific code, based on one developed by Brownlee and others, that permits more detailed specification of both antibradycardia and antitachycardia functions. The specific code described in this report was adopted by the NASPE Executive Advisory Committee as the NASPE Specific Code in March, 1983. The generic code was not adopted but is described herein for future reference in the light of experience to he gained in the use of the recently published Revised ICHD Code.
Double Ventricular Pacing in a Patient with a “DDD” Universal Pacemaker
Authors: NATHAN ANTHONY W. , CAMM A. JOHN
Published: July 2006

A patient with a DDD universal pacemaker presented with dyspnea. The electrocardiogram showed pacing artifacts both at the start of the QRS complex and 110 ms later. Also, 400 ms following sensed ventricular extrasystoles, there were normal single paced QHS complexes of slightly different morphology. An x‐ray showed that the atrial electrode had displaced into the ventricle, and at exploration this was found to be due to late retraction of the electrode's active fixation helix. Following implantation of a new atrial lead, normal DDD pacing function was restored and the patient became asymptomatic.
The Automatic Implantable Cardioverter‐Defibrillator
Authors: MIROWSKI M. , REID PHILIP R. , MOWER MORTON M. , WATKINS LEVI , PLATIA EDWARD V. , GRIFFITH LAWRENCE S.C. , JUANTEGUY JUAN M.
Published: July 2006

The automatic implantable cardioverter‐defibrillator is an electronic device designed to monitor the heart continuously, to identify malignant ventricular tachyarrhythmias, and then to deliver effective countershock to restore normal rhythm. There are two defibrillating electrodes which are also used for waveform analysis; one is located in the superior vena cava, the other is placed over the cardiac apex. A third bipolar right ventricular electrode serves for rate counting and R‐wave synchronization. When ventricular fibrillation occurs, a 25 joule pulse is delivered; when ventricular tachycardia faster than a preset rate is detected, the discharge is R‐wave synchronized. The device can recycle three times if required. Special batteries can deliver over 100 shocks or provide a 3‐year monitoring life. Implantation of the device is made either through a thoracotomy or by a subxiphoid approach. Thus far, the device has been implanted in 160 patients with a follow‐up of 42 months. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation occurred only rarely and is dealt with most successfully through recycling. Actuarial analysis of the initial 52 patients has indicated 22.9% one‐year total mortality, a 52% decrease from the 48% mortality that would be expected in the same group of patients without the device: the mortality attributed to arrhythmias was only 8.5%. In conclusion, the automatic cardioverter‐defibrillator can reliably identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in survival in properly selected high‐risk patients.
Clinical Experience with Implantable Devices for Control of Tachyarrhythmias
Authors: DULK KAREL den , BERTHOLET MICHEL , BRUGADA PEDRO , BÄR FRITS W. , DEMOULIN JEAN C. , WALEFFE ANDRE , BAKELS NOUD , LINDEMANS FRED , BOURGEOIS IVAN , KULBERTUS HENRI E. , WELLENS HEIN J.J.
Published: July 2006

Pacing is becoming an accepted form of treatment for reentry tachycardias. The different pacing modalities available and experience with a patient‐activated antitachycardia pacemaker are presented in this paper. This system has bidirectional communication between pacemaker and pacemaker‐activator and between pacemaker and prescription formulator (which is a sophisticated portable stimulator used for non‐invasive electrophysiological evaluation of the system). This pacemaker was implanted in 18 patients with drug‐resistant tachycardias. Six patients had ventricular tachycardia, 3 had A‐V nodal reentrant tachycardia, 4 had the concealed accessory pathway, and 5 had the WPW syndrome. In the 3 months before implantation the mean number of admissions for termination of tachycardia was 2.1 per patient‐month. During a follow‐up period of 3–26 months only 6 patients were admitted once for termination of tachycardia (0.02 admissions per patient‐month). The reasons for admission of these 6 patients were: defective pacemaker activator in 2 patients, inadequate control of tachycardia in 2 patients, inappropriate use of the device in 1, and inadequate intake of medication in 1. All these problems were solved easily. Eight pacemaker activators required reprogramming, which was done in 5 patients on an out‐patient basis. The interval scanning mode was used in 9 patients. Nine patients required more than 2 stimuli for reproducible termination. A step‐wise increase in number of stimuli was used in 5 patients.

This system has proven to be a safe and effective form of treatment of drug‐resistant supraventricular and ventricular tachycardias and has resulted in marked improvement of the quality of life of these patients.
Multiform Ventricular Ectopic Rhythm by Combined Parasystolic and Reentrant Activities
Authors: LOPERFIDO FRANCESCO , ANSALONE GERARDO , SANTARELLI PIETRO , BELLOCCI FULVIO
Published: July 2006

Multiform ventricular ectopic rhythm (MVER), i.e., at least two QRS configurations of ventricular ectopic beats (VEBs), was assessed by 24‐hour ambulatory ECG recording in four patients with ventricular parasystole (VP). In two of these four patients, VEBs with fixed coupling to the preceding impulses coexisted with VP beats of different configuration. In case no. 1, the VEBs had an identical coupling interval to sinus bents and VP beats, suggesting a mechanism of reentry elicited from both dominant pacemakers. In case no. 2, an intermittent form of VP due to type II second‐degree entrance block was present. In this patient, the VEBs were coupled to sinus beats and to sinus‐VP fusion beats and appeared to be dependent on the sinus beats reaching the VP focus. A mechanism of reentry determined by the penetration of sinus beats into the VP area, with prematurity‐dependent aberrancy of VEBs, was suggested for the coupled VEBs in this patient. These observations suggest that the coexistence of an automatic ventricular ectopic focus and of a reentrant activity determined by, or elicited from, an area of automaticity may constitute the underlying mechanism of MVER in some patients.
Serial Electrophysiologic Testing with a Permanent Pacemaker after Acute Myocardial Infarction
Authors: LUCK JERRY C. , WYNDHAM CHRISTOPHER R.C. , MANN DAVID E. , BATTY JOHN W. , HERRE JOHN M. , GRIFFIN JERRY C.
Published: July 2006

Electrophysiologic testing in patients after acute myocardial infarction may predict subsequent sudden death. We used a permanent pacemaker for repetitive electrophysiologic testing in a patient after acute infarction. Programmed, twice‐threshold ventricular extrastimulation at two weeks after anteroseptal infarction failed to induce ventricular tachycardia. Subsequent programmed extrastimulation induced sustained ventricular tachycardia on four occasions (6, 16, 29 and 65 weeks) after infarction. As yet (20 months), spontaneous ventricular tachycardia has not occurred. Firm conclusions cannot be drawn from a single case. However, our patient developed a stable ventricular tachycardia circuit which was not apparent at two weeks. Thus, a single electrophysiologic study performed acutely after infarction may not accurately describe the potential for ventricular tachycardia or fibrillation. Serial electrophysiologic testing with an implantable externally triggered pacemaker may more accurately describe the potential for sudden death post‐infarction in a few high‐risk patients. This report shows that induction of ventricular tachycardia after acute infarction may not predict outcome.
Temporary A‐V Sequential Pacing Using Chest Wall Stimulation
Authors: KERSSCHOT IVO E. , VANAGT EDDY J. , VRINTS CHRIS J. , BOSSAERT LEO L. , SNOECK JOZEF P.
Published: July 2006

We describe the therapeutic application of chest wall stimulation enabling temporary A‐V sequential pacing in patients with an implanted VVT pacemaker following the transvenous introduction of only one temporary electrode.
One Turn More: Threshold Superiority of 3‐turn versus 2‐turn Screw‐in Myocardial Electrodes
Authors: KORHONEN ULLA , KÄRKÖLÄ PENTTI , TAKKUNEN JUHA , POKELA RISTO
Published: July 2006

Epicardial electrodes are an alternative for patients in whom the transvenous approach presents technical difficulties. We have had clinical experience with two types of myocardial sutureless electrodes inserted in the anterior left ventricular wall: the 3‐turn screw‐in electrode (Medtronic 6917) was used in 209 patients from 1974 to 1977 and the 2‐turn screw‐in lead (Medtronic 6917 A) was used in 61 patients from 1978 to 1981. The initial threshold was equal and acceptable with both types of electrodes.

During a follow‐up period (up to 48 months), critical elevation of the pacing threshold resulting in exit block was found in 12% (25) of the patients with the 3‐turn screw‐in electrode and in 20% (12) of the patients with the 2‐turn electrode (p < 0.05). Elevation of the pacing threshold developed fairly early, usually within 6 months, with the 2‐turn screw‐in electrode, but much later, within 2–4 years, with the 3‐turn electrode. During a longer follow‐up time of up to 96 months the frequency of exit block increased up to 16% with the 3‐turn electrode.

Our results indicate that late critical elevation of the pacing threshold is surprisingly frequent with screw‐in electrodes inserted into the left ventricular myocardium, and it is especially common with the 2‐turn screw‐in electrode.
Amiodarone for Refractory Automatic Atrial Tachycardia: Observations on the Electrophysiological Actions of Amiodarone
Authors: WIENER ISAAC , LYONS HOLLY
Published: July 2006

A patient with automatic atrial tachycardia refractory to all conventional therapies is described. Amiodarone controlled the tachycardia by causing a progressive decrease in the rate of discharge from the atrial focus. We conclude that 1) amiodarone was effective therapy for automatic atrial tachycardia, avoiding the need for nonmedical therapy; and 2) amiodarone appeared to act by decreasing spontaneous automaticity.